rifampin and Actinomycetales-Infections

Pneumonia caused by Rhodococcus equi remains an important cause of disease and death in foals. The combination of a macrolide (erythromycin, azithromycin, or clarithromycin) with rifampin remains the recommended therapy for foals with clinical signs of infection caused by R equi. Most foals with small, subclinical ultrasonographic pulmonary lesions associated with R equi recover without therapy, and administration of antimicrobial agents to these subclinically affected foals does not hasten lesion resolution relative to administration of a placebo. Resistance to macrolides and rifampin in isolates of R equi is increasing.

Topics: Actinomycetales Infections; Animals; Anti-Bacterial Agents; Azithromycin; Clarithromycin; Drug Resistance, Multiple, Bacterial; Erythromycin; Horse Diseases; Horses; Pneumonia, Bacterial; Rhodococcus equi; Rifampin

Infection with Rhodococcus equi is an important cause of pneumonia in foals, but other organ systems may also be affected. The intracellular presence of R. equi and the formation of granulomatous and suppurative inflammatory tissue mean that prolonged treatment is needed. The pharmacological properties of the combination of erythromycin and rifampicin have improved the survival of foals infected with R. equi; however, erythromycin can cause adverse reactions in foals and mares, which has prompted the search for alternative therapies. The combination of azithromycin or clarithromycin with rifampicin seems to be a promising alternative. However these combinations are expensive and adverse effects remain to be determined, especially in the dams of treated foals. Thus correct diagnosis and appropriate use of drugs are essential for the treatment of R. equi infection in foals.

Topics: Actinomycetales Infections; Animals; Animals, Newborn; Anti-Bacterial Agents; Azithromycin; Clarithromycin; Drug Therapy, Combination; Erythromycin; Horse Diseases; Horses; Pneumonia, Bacterial; Rhodococcus equi; Rifampin; Treatment Outcome

We have reported a case of isolated bacteremia due to Rhodococcus equi in an immunocompromised, non-HIV-infected patient with acute leukemia. This patient's illness demonstrates a rare presentation of an emerging opportunistic pathogen that may be potentially acquired via exposure to domestic horses or their habitat during periods of aggressive chemotherapeutic administration. The infection was successfully eradicated by treatment with erythromycin and rifampin. Counseling immunocompromised patients inclined to participate in recreational activities involving potential risks of exposure to this pathogen would seem to be a reasonable, but unproven, preventive intervention.

Topics: Actinomycetales Infections; Adult; Animals; Antineoplastic Agents; Bacteremia; Erythromycin; Horses; Humans; Karyotyping; Leukemia, Promyelocytic, Acute; Leukocyte Count; Male; Neutropenia; Remission Induction; Rhodococcus equi; Rifampin

Rhodococcus equi is an emerging opportunistic pathogen of HIV-I infected patients. It is an aerobic, Gram-positive coryneform bacterium which acts as a facultative intracellular micro-organism, multiplying in the phagosome of macrophages. Eighteen cases of R. equi infection in HIV-I positive patients have now been reported. Sixteen of these had pneumonia, of which 12 had cavitating lung lesions. A history of contact with farm animals, which are the primary hosts of R. equi, was found in only three patients. There was a delay in establishing a definite diagnosis in most cases as this depended upon the isolation of R. equi from sputum, bronchoalveolar lavage fluid, or blood. Treatment included surgical resection in five patients and erythromycin with a second antibiotic in 13 cases, but II of the 18 patients died from the infection. In this report we describe our experience of R. equi pneumonia in two AIDS patients and review the published cases of the disease in man.

Topics: Acquired Immunodeficiency Syndrome; Actinomycetales Infections; Adult; Amoxicillin; Amoxicillin-Potassium Clavulanate Combination; Clavulanic Acids; Doxycycline; Drug Therapy, Combination; HIV Seropositivity; HIV-1; Humans; Male; Microbial Sensitivity Tests; Pneumonia; Rhodococcus equi; Rifampin

Rhodococcus equi is an aerobic, gram-positive, non-motile pleomorphic bacillus infecting immunocompromised patients. Forty-nine cases of Rhodococcus equi infection have been reported, mainly in patients infected with the human immunodeficiency virus (HIV). A case in which Rhodococcus equi caused severe pulmonary infection, the most common presentation, is described. Clinically, patients have symptoms of pneumonia with hemoptysis as a prominent feature. X-ray will often show a cavitating upper-lobe infiltrate, resembling infection with mycobacteria. Rhodococcus equi is easily cultured from blood or sputum on standard media, but is frequently regarded as a contaminant. Mortality from Rhodococcus equi pneumonia is high (25%) and early surgical intervention has been recommended. Based on this review, the benefit of surgery seems dubious, whereas good results have been obtained using long-term antibiotic treatment with erythromycin plus rifampicin, or vancomycin in combination with either of these antibiotics.

Topics: Acquired Immunodeficiency Syndrome; Actinomycetales Infections; Adult; Drug Therapy, Combination; Erythromycin; Humans; Immunocompromised Host; Male; Pneumonia; Rhodococcus equi; Rifampin; Vancomycin

Corynebacterium (Rhodococcus) equi is becoming increasingly significant as a cause of bronchopneumonia and lung abscessation in foals. The organism can survive within macrophages and may thus escape normal pulmonary defence mechanisms, particularly in immunocompromised animals. The disease has hitherto been associated with mortality rates as high as 80 per cent, partly as a result of inappropriate therapy. The selection of lipid-soluble antibiotics capable of intracellular penetration is critical for the successful treatment of C equi lung abscesses. A combination of two such antibiotics, erythromycin (25 mg/kg three times daily) and rifampicin (5 mg/kg twice daily) has been used on foals since 1981. Most of these animals had radiographic evidence of extensive lung abscessation, and in all cases the presence of C equi was confirmed on culture of tracheal aspirates. The duration of therapy ranged from four to nine weeks. Mild gastritis and diarrhoea were occasionally noted, but never such as to require termination of the therapy. No other adverse side effects were encountered. The success rate, as judged by a return to normal of chest radiographs and plasma fibrinogen concentrations, has exceeded 80 per cent.

Topics: Actinomycetales Infections; Animals; Drug Therapy, Combination; Erythromycin; Horse Diseases; Horses; Lung Abscess; Rhodococcus; Rifampin

There is conflicting data regarding the efficacy of tulathromycin for the treatment of foals with bronchopneumonia.. Tulathromycin is effective for the treatment of bronchopneumonia in foals and noninferior to the combination of azithromycin and rifampin.. A total of 240 foals on a farm endemic for infections caused by Rhodococcus equi.. In a controlled, randomized, and double-blinded clinical trial, foals with ultrasonographic pulmonary lesions (abscess score 10-15 cm) were allocated to 3 groups: 1-tulathromycin IM q 7 days (n = 80); 2-azithromycin-rifampin, orally q24h (n = 80); or 3-untreated controls (n = 80). Physical examination and thoracic ultrasonography were performed by individuals unaware of treatment group assignment. Foals that worsened were considered treatment failures and removed from the study.. The proportion of foals that recovered was significantly higher for foals treated with tulathromycin (70 of 79) or azithromycin-rifampin (76 of 80) compared to that of control foals (22 of 80). The difference in the percentage of efficacy of azithromycin-rifampin versus tulathromycin was 6.4% (90% CI = -0.72-13.5%). Given that the confidence interval crossed the predetermined noninferiority limit of 10%, the null hypothesis that the response rate in the azithromycin-rifampin group is superior to that of the tulathromycin group could not be rejected. Resolution of ultrasonographic lesions occurred faster in foals treated with azithromycin-rifampin than in foals treated with tulathromycin.. Tulathromycin was effective for the treatment of bronchopneumonia in foals at this farm but not as effective as the combination of azithromycin-rifampin.

Topics: Actinomycetales Infections; Animals; Anti-Bacterial Agents; Azithromycin; Bronchopneumonia; Disaccharides; Double-Blind Method; Drug Therapy, Combination; Female; Heterocyclic Compounds; Horse Diseases; Horses; Male; Rhodococcus equi; Rifampin; Treatment Outcome

Gamithromycin is active in vitro against the bacterial agents most commonly associated with bronchopneumonia in older foals. However, the clinical efficacy and safety of this drug have not been investigated.. Gamithromycin is effective for the treatment of bronchopneumonia in foals.. One hundred and twenty-one foals on a farm endemic for infections caused by Rhodococcus equi.. In a controlled, randomized, and double blinded clinical trial, foals with ultrasonographic evidence of pulmonary abscesses (abscess score 8.0-20 cm) were randomly allocated in 3 treatment groups: (1) gamithromycin IM q7 days (n = 40); (2) azithromycin with rifampin, PO q24h (n = 40); or (3) no antimicrobial treatment (controls; n = 41). Physical examination and thoracic ultrasonography were performed by individuals unaware of treatment group assignment. Foals that worsened were removed from the study.. The proportion of foals that recovered without the need to be removed from the study was significantly higher for foals treated with gamithromycin (38 of 40) or azithromycin with rifampin (39 of 40) than for controls (32 of 41). Treatment with gamithromycin or with azithromycin-rifampin resulted in a significantly faster decrease in the clinical score and abscess score compared to the controls. Adverse reactions characterized by colic (n = 18) and hind limb lameness (n = 14) were observed only in foals treated with gamithromycin.. Gamithromycin was noninferior to azithromycin with rifampin for the treatment of bronchopneumonia in the study population but had a higher frequency of adverse reactions.

Topics: Abscess; Actinomycetales Infections; Animals; Anti-Bacterial Agents; Azithromycin; Bronchopneumonia; Double-Blind Method; Drug Therapy, Combination; Female; Horse Diseases; Horses; Macrolides; Male; Rhodococcus equi; Rifampin

The objectives of the present study were to determine the relative efficacy of tulathromycin, azithromycin, or azithromycin with rifampin for the treatment of pulmonary abscesses on a farm with endemic infections caused by Rhodococcus equi. Foals with ultrasonographic evidence of pulmonary abscesses (abscess score 8.0-15 cm; n=120) were randomly allocated in four equal treatment groups: (1) tulathromycin intramuscularly; (2) azithromycin monotherapy, orally; (3) azithromycin with rifampin, orally; (4) saline intramuscularly as a placebo. Physical examination and thoracic ultrasonography were performed by individuals unaware of treatment group assignment. Foals that worsened were removed from the study. The proportion of foals that recovered without the need for a change in therapy was significantly higher for foals treated with azithromycin (29 of 30) or azithromycin with rifampin (28 of 30) than for foals treated with a placebo (20 of 30). Additionally, azithromycin or azithromycin with rifampin resulted in a significantly faster decrease in the number of abscesses and abscess score compared with a placebo. The proportion of foals treated with tulathromycin that recovered (27 of 30) was not significantly different from that of foals treated with a placebo. Azithromycin alone or in combination with rifampin was beneficial in the study population.

Topics: Actinomycetales Infections; Animals; Anti-Bacterial Agents; Azithromycin; Disaccharides; Double-Blind Method; Drug Therapy, Combination; Endemic Diseases; Germany; Heterocyclic Compounds; Horse Diseases; Horses; Lung Abscess; Pneumonia, Bacterial; Rhodococcus equi; Rifampin; Severity of Illness Index; Treatment Outcome

Mass antimicrobial treatment of foals with small ultrasonographic pulmonary lesions is common on farms with endemic disease caused by Rhodococcus equi. The objectives of this study were to compare the relative efficacy of three antimicrobial protocols for the treatment of pulmonary abscesses on a farm with endemic infections caused by R. equi and to determine the frequency of spontaneous resolution of subclinical pulmonary lesions. Foals with ultrasonographic evidence of pulmonary abscesses ≥ 1.0 cm in diameter (n=128) were randomly allocated to one of four equal treatment groups. Animals with respiratory distress or severe pulmonary lesions were excluded from the study. Treatment groups consisted of: (1) tulathromycin intramuscularly; (2) azithromycin monotherapy orally; (3) azithromycin in combination with rifampin orally; and (4) glucose orally as a placebo. Physical examination, thoracic ultrasonography and white blood cell (WBC) counts were performed weekly by individuals unaware of treatment group assignment. Foals that worsened were removed from the study and treated with azithromycin and rifampin. Overall, 14/32 (43.8%) foals in the placebo group recovered without the need for therapy. The proportion of foals that responded to the initial therapy, the duration of therapy, the kinetics of ultrasonographic lesion resolution, the proportion of foals that had to be removed from the study and the number of days to removal from the study did not differ significantly between treatment groups. The study showed that many foals with pulmonary abscesses recover without antimicrobial therapy. Moreover, treatment of sub-clinically affected foals with antimicrobial agents did not significantly hasten recovery.

Topics: Actinomycetales Infections; Animals; Anti-Bacterial Agents; Azithromycin; Disaccharides; Double-Blind Method; Drug Therapy, Combination; Endemic Diseases; Female; Heterocyclic Compounds; Horse Diseases; Horses; Lung Abscess; Male; Rhodococcus equi; Rifampin; Time Factors; Treatment Failure

Rhodococcus equi is a soil borne bacterium that causes severe morbidity and death in young foals. The economic costs of the disease include loss of life, treatment expenses, veterinary monitoring expenses and, perhaps most importantly, potential reduction in future athletic performance in horses that suffer severe lung abscessations caused by R. equi. Current standard of care for pneumonia caused by R. equi is treatment with a macrolide antimicrobial and rifampicin. However, the hallmark of pneumonia caused by R. equi is severe formation of pyogranulomas and a walling off effect that can prevent systemic antibiotics from reaching antimicrobial concentrations in lung tissues. It is hypothesized that streptolysin O (SLO) used as an adjunct therapy with antibiotics will reduce the duration and severity of disease caused by R. equi pneumonia compared to antibiotic therapy alone. Addition of SLO to the antibiotic enhanced clinical responses compared to the other groups, including the antibiotic alone group. Of particular significance were lower bacterial counts in the lungs and longer survival time in those foals treated with SLO and antibiotics.

Topics: Actinomycetales Infections; Animals; Anti-Bacterial Agents; Bacterial Proteins; Fibrinogen; Horse Diseases; Horses; Lung; Macrolides; Pneumonia, Bacterial; Rhodococcus equi; Rifampin; Streptolysins

The selection of lipid-soluble antibiotics capable of intracellular penetration is considered critical for the successful treatment of Rhodococcus equi pneumonia and lung abscesses in foals. Two such antibiotics: erythromycin (25 mg kg-1, three times daily) and rifampin (5 mg kg-1 twice daily) have been used in combination for this purpose at the University of Florida since 1981. Positive evidence of R. equi was present on culture of tracheal aspirates in 57 foals, most of which exhibited radiographic evidence of extensive lung abscessation. The duration of therapy ranged from 4 to 9 weeks. Mild diarrhea was sometimes noted, but was never severe enough to require the termination of therapy. No other adverse side effects were apparent. Judged by a return of chest radiographs and hematologic parameters to normal, 50 of the 57 foals were considered to have recovered from the disease; a success rate of 88%.

Topics: Actinomycetales Infections; Animals; Animals, Newborn; Clinical Trials as Topic; Drug Therapy, Combination; Erythromycin; Horse Diseases; Horses; Pneumonia; Rhodococcus; Rifampin

A multidrug-resistant clone of the animal and human pathogen Rhodococcus equi, MDR-RE 2287, has been circulating among equine farms in the United States since the 2000s. We report the detection of MDR-RE 2287 outside the United States. Our finding highlights the risk for MDR-RE spreading internationally with horse movements.

Topics: Actinomycetales Infections; Animals; Anti-Bacterial Agents; Drug Resistance, Bacterial; Horse Diseases; Horses; Humans; Macrolides; Rhodococcus equi; Rifampin; United States

Rhodococcus equi (R. equi) infections are endemic in many horse facilities in the United States resulting significant economic loses annually. Currently, there is no commercial vaccine available and the emergence of isolates that are resistant to the current treatment and prophylaxis using antibiotics prompts closer surveillance of this pathogen.. This study compares three different genotyping techniques, Pulsed Field Gel Electrophoresis (PFGE), Multilocus Sequence Typing (MLST) and whole genome SNP-based phylogeny to determine the most accurate method to monitor the spread of macrolide-and-rifampin-resistant R. equi.. 16 macrolide and rifampin-resistant and 6 susceptible R. equi and their Illumina Miseq whole genome sequences were used in this study. The isolates were sub-typed by PFGE with VspI and a dendrogram based on their similarities generated. Additionally, three phylogenetic trees were constructed using CSI phylogeny on (i) whole genome sequences (WGS), (ii) in silico MLST sequences and (iii) MLST sequences obtained after PCR-amplification and Sanger sequencing.. PFGE identified 18 different genetic profiles and grouped the 22 isolates into 3 clusters independently of their susceptibilities. The phylogenetic trees built from WGS and MLST data showed similar topology, separating the isolates into 2 major clades in accordance with their susceptibility profiles (susceptible and resistant). However, only the trees generated with next generation sequencing data could detect the clonality of the resistant isolates.

Topics: Actinomycetales Infections; Animals; Anti-Bacterial Agents; Bacterial Typing Techniques; Drug Resistance, Multiple, Bacterial; Electrophoresis, Gel, Pulsed-Field; Genotyping Techniques; Horse Diseases; Horses; Macrolides; Microbial Sensitivity Tests; Multilocus Sequence Typing; Phylogeny; Rhodococcus equi; Rifampin; Sequence Analysis, DNA; Whole Genome Sequencing

Cellulosimicrobium cellulans is a gram-positive filamentous bacterium found primarily in soil and sewage that rarely causes human infection, especially in previously healthy adults, but when it does, it often indicates a poor prognosis.. We report a case of endocarditis and intracranial infection caused by C. cellulans in a 52-year-old woman with normal immune function and no implants in vivo. The patient started with a febrile headache that progressed to impaired consciousness after 20 days, and she finally died after treatment with vancomycin combined with rifampicin. C. cellulans was isolated from her blood cultures for 3 consecutive days after her admission; however, there was only evidence of C. cellulans sequences for two samples in the second-generation sequencing data generated from her peripheral blood, which were ignored by the technicians. No C. cellulans bands were detected in her cerebrospinal fluid by second-generation sequencing.. Second-generation sequencing seems to have limitations for certain specific strains of bacteria.

Topics: Actinobacteria; Actinomycetales Infections; Blood Culture; Diagnosis, Differential; Endocarditis; Fatal Outcome; Female; Humans; Middle Aged; Rifampin; Sequence Analysis, DNA; Vancomycin

The objective of this study was to determine the prevalence of

Topics: Actinomycetales Infections; Animals; Anti-Bacterial Agents; Azithromycin; Clarithromycin; Drug Resistance, Multiple, Bacterial; Equidae; Erythromycin; Feces; Horses; Kentucky; Microbial Sensitivity Tests; Musculoskeletal Diseases; Prevalence; Respiratory System; Rhodococcus equi; Rifampin; Soft Tissue Infections

Rhodococcus equi causes severe pneumonia in foals and is most often recognized in people as an opportunistic pathogen. Longitudinal studies examining antimicrobial-resistant R. equi from environmental samples are lacking. We hypothesized that antimicrobial-resistant R. equi would be detectable in the ground (pasture soil or stall bedding) and air at breeding farms with previous documentation of foals infected with resistant isolates, and that concentrations of resistant isolates would increase over time during the foaling season. In this prospective cohort study, ground and air samples were collected from stalls and paddocks in January, March, May and July of 2018 at 10 horse-breeding farms with history of foal pneumonia attributed to macrolide- or Rifampicin-resistant R. equi. Environmental samples were cultured in the presence and absence of macrolides and Rifampicin to select for resistant organisms. Data were analyzed with linear mixed-effects and Hurdle models. Concentrations of total R. equi in bedding or air of stalls were significantly (P < 0.05) higher in January than other months. The proportion of resistant R. equi in soil samples from paddocks was significantly (P < 0.05) higher than stall bedding during all months. For each month, air samples from paddocks had a significantly (P < 0.05) higher proportion of resistant isolates than those from stalls. Fifty-five percent of resistant soil isolates and 34% of resistant air isolates were considered virulent by identification of the vapA gene. Concentrations of resistant R. equi isolates did not increase over time during the foaling season. Antimicrobial-resistant R. equi can persist in the environment at farms with a history of pneumonia caused by resistant R. equi infections, and exposure to resistant isolates in paddocks and stalls appears stable during the foaling season. Resistant isolates in the environment not only pose a risk for disease but also can serve as a repository for dissemination of resistance genes.

Topics: Actinomycetales Infections; Air Microbiology; Animal Husbandry; Animals; Breeding; Drug Resistance, Multiple, Bacterial; Farms; Horse Diseases; Horses; Housing, Animal; Kentucky; Macrolides; Pneumonia, Bacterial; Prospective Studies; Rhodococcus equi; Rifampin; Seasons; Soil Microbiology; Virulence

The combination of a macrolide and rifampicin has been the mainstay of therapy in foals with Rhodococcus equi pneumonia for decades. Recent studies suggest that mass antimicrobial treatment of subclinically affected foals over time has selected for antimicrobial resistance. Our objective was to estimate the prevalence of R. equi strains resistant to macrolides and rifampicin at horse breeding farms in Kentucky. A hundred breeding farms in Kentucky were surveyed and R. equi were cultured from soil samples. Data were analyzed with logistic regression and generalized linear modeling (P < 0.05). Seventy-six percent (76%) of farms yielded resistant R. equi, and resistance to macrolides and rifampicin was associated with their use at farms. The present study is the first to report the prevalence and distribution of resistant isolates in the environment of farms in Kentucky, USA. Collectively, previous reports and the data presented herein provide irrefutable evidence of emerging antimicrobial resistance in R. equi with alarming prevalence. Widespread dissemination and maintenance of resistance genes in the environment where many other pathogenic bacteria exist is a concern for both animal and human health.

Topics: Actinomycetales Infections; Animals; Anti-Bacterial Agents; Breeding; Drug Resistance, Multiple, Bacterial; Farms; Horse Diseases; Horses; Kentucky; Macrolides; Prevalence; Rhodococcus equi; Rifampin; Risk Factors

Topics: Actinomycetales Infections; Animals; Anti-Bacterial Agents; Azithromycin; Drug Combinations; Drug Compounding; Drug Synergism; Humans; Microbial Sensitivity Tests; Powders; Rhodococcus equi; Rifampin; THP-1 Cells; Toxicity Tests; Zoonoses

Rhodococcus equi, a facultative intracellular pathogen and an important cause of pneumonia in foals, is highly susceptible to killing by gentamicin in vitro. However, gentamicin is not effective in vivo, due to its poor cellular penetration. Encapsulation of drugs in liposomes enhances cellular uptake. The objectives of this study were to compare liposomal gentamicin and free gentamicin with respect to their uptake by equine macrophages and intracellular colocalization with R. equi and to compare the efficacies of liposomal gentamicin, free gentamicin and clarithromycin with rifampin for the reduction of R. equi CFU in a mouse model of infection. After ex vivo exposure, a significantly higher mean (±SD) percentage of equine alveolar macrophages contained liposomal gentamicin (91.9±7.6%) as opposed to free gentamicin (16.8±12.5%). Intracellular colocalization of drug and R. equi, as assessed by confocal microscopy, occurred in a significantly higher proportion of cells exposed to liposomal gentamicin (81.2±17.8%) compared to those exposed to free gentamicin (10.4±8.7%). The number of R. equi CFU in the spleen was significantly lower in mice treated with liposomal gentamicin compared to that of mice treated with free gentamicin or to untreated control mice. Treatment with liposomal gentamicin also resulted in a significantly greater reduction in the number of R. equi CFU in the liver compared to treatment with clarithromycin in combination with rifampin. These results support further investigation of liposomal gentamicin as a new treatment for infections caused by R. equi.

Topics: Actinomycetales Infections; Animals; Anti-Bacterial Agents; Clarithromycin; Disease Models, Animal; Gentamicins; Horse Diseases; Horses; Liposomes; Liver; Macrophages, Alveolar; Male; Mice; Mice, Nude; Pneumonia; Rhodococcus equi; Rifampin; Spleen

Treatment of mice with the combination of clarithromycin with rifampin resulted in a significantly lower number of Rhodococcus equi CFU in the organs of mice than treatment with either drug alone or placebo. There was no significant difference in the number of R. equi CFU between mice treated with clarithromycin monotherapy, rifampin monotherapy, or placebo. The combination of clarithromycin with rifampin conferred a clear advantage over either drug as monotherapy in this model of chronic R. equi infection.

Topics: Actinomycetales Infections; Animals; Anti-Bacterial Agents; Clarithromycin; Drug Combinations; Male; Mice; Mice, Nude; Microbial Sensitivity Tests; Rhodococcus equi; Rifampin

Topics: Actinomycetales Infections; Aged; Anti-Bacterial Agents; Bacteremia; Ciprofloxacin; Diagnosis, Differential; Drug Therapy, Combination; Fertilizers; Humans; Imipenem; Immunocompromised Host; Leukemia, Myelomonocytic, Chronic; Lung Abscess; Lung Neoplasms; Male; Manure; Opportunistic Infections; Rhodococcus equi; Rifampin; Shock, Septic; Tomography, X-Ray Computed

Rhodococcus equi, the causal agent of rhodococcosis, is a major pathogen of foals and is also responsible for severe infections in immunocompromised humans. Of great concern, strains resistant to currently used antibiotics have emerged. As the number of drugs that are efficient in vivo is limited because of the intracellular localization of the bacterium inside macrophages, new active but cell-permeant drugs will be needed in the near future. In the present study, we evaluated, by in vitro and ex vivo experiments, the ability of the alpha-helical equine antimicrobial peptide eCATH1 to kill intracellular bacterial cells. Moreover, the therapeutic potential of the peptide was assessed in experimental rhodococcosis induced in mice, while the in vivo toxicity was evaluated by behavioral and histopathological analysis. The study revealed that eCATH1 significantly reduced the number of bacteria inside macrophages. Furthermore, the bactericidal potential of the peptide was maintained in vivo at doses that appeared to have no visible deleterious effects for the mice even after 7 days of treatment. Indeed, daily subcutaneous injections of 1 mg/kg body weight of eCATH1 led to a significant reduction of the bacterial load in organs comparable to that obtained after treatment with 10 mg/kg body weight of rifampin. Interestingly, the combination of the peptide with rifampin showed a synergistic interaction in both ex vivo and in vivo experiments. These results emphasize the therapeutic potential that eCATH1 represents in the treatment of rhodococcosis.

Topics: Actinomycetales Infections; Animals; Anti-Infective Agents; Cell Line; Macrophages, Peritoneal; Mice; Mice, Inbred BALB C; Microscopy, Fluorescence; Rhodococcus equi; Rifampin

The objectives of this study were to determine the mutant prevention concentration (MPC), time above the MPC and mutant selection window for 10 antimicrobial agents against Rhodococcus equi and to determine if the combination of a macrolide with rifampin would decrease emergence of resistant mutants. Antimicrobial agents investigated (erythromycin, clarithromycin, azithromycin, rifampin, amikacin, gentamicin, enrofloxacin, vancomycin, imipenem, and doxycycline) were selected based on in vitro activity and frequency of use in foals or people infected with R. equi. Each antimicrobial agent or combination of agents was evaluated against four virulent strains of R. equi. MPC were determined using an agar plate assay. Pharmacodynamic parameters were calculated using published plasma and pulmonary pharmacokinetic variables. There was a significant (P<0.001) effect of the type of antimicrobial agent on the MPC. The MPC of clarithromycin (1.0 μg/ml) was significantly lower and the MPC of rifampin and amikacin (512 and 384 μg/ml, respectively) were significantly higher than that of all other antimicrobial agents tested. Combining erythromycin, clarithromycin, or azithromycin with rifampin resulted in a significant (P≤0.005) decrease in MPC and MPC/MIC ratio. When MIC and MPC were combined with pharmacokinetic variables, only gentamicin and vancomycin were predicted to achieve plasma concentrations above the MPC for any given periods of time. Only clarithromycin and the combination clarithromycin-rifampin were predicted to achieve concentrations in bronchoalveolar cells and pulmonary epithelial lining fluid above the MPC for the entire dosing interval. In conclusion, the combination of a macrolide with rifampin considerably decreases the emergence of resistant mutants of R. equi.

Topics: Actinomycetales Infections; Animals; Anti-Bacterial Agents; Azithromycin; Clarithromycin; Erythromycin; Gentamicins; Horse Diseases; Horses; Macrolides; Microbial Sensitivity Tests; Mutation; Rhodococcus equi; Rifampin; Vancomycin

Peritonitis is an important cause of morbidity in patients undergoing peritoneal dialysis. Rothia mucilaginosa has been reported as an unusual cause of peritoneal dialysis associated peritonitis. Difficulty in the management of this microorganism lies in the absence of uniform recommendations for anti-microbial therapy directed against this pathogen. The current report describes the clinical course of an episode of peritoneal dialysis associated peritonitis caused by Rothia mucilaginosa. Treatment options for this organism are summarized.

Topics: Actinomycetales Infections; Administration, Oral; Adult; Drug Therapy, Combination; Female; Humans; Infusions, Parenteral; Micrococcaceae; Peritoneal Dialysis; Peritonitis; Rifampin; Treatment Outcome; Vancomycin

Macrolide and rifampin resistance developed on a horse breeding farm after widespread use was instituted for treatment of subclinical pulmonary lesions in foals. Resistance occurred in 6 (24%) of 25 pretreatment and 8 (62%) of 13 (62%) posttreatment isolates from affected foals. Drug-resistant isolates formed 2 distinct genotypic clusters.

Topics: Actinomycetales Infections; Animals; Asymptomatic Infections; Breeding; Drug Resistance, Multiple, Bacterial; Genes, Bacterial; Horse Diseases; Horses; Kentucky; Macrolides; Molecular Typing; Phylogeny; Pneumonia, Bacterial; Repetitive Sequences, Nucleic Acid; Rhodococcus equi; Rifampin; Ultrasonography

We describe two cases of prosthetic valve endocarditis caused by Propionibacterium spp. successfully treated with a combination of rifampin and intravenous penicillin. Rifampin was chosen due to its promising activity against planktonic and biofilm Propionibacterium, its favourable minimal inhibitory concentrations, its excellent oral bioavailability and tissue penetration.

Topics: Actinomycetales Infections; Aged; Anti-Bacterial Agents; Aortic Valve; Bioprosthesis; Drug Therapy, Combination; Endocarditis, Bacterial; Female; Heart Valve Prosthesis; Humans; Male; Middle Aged; Penicillins; Propionibacterium; Rifampin

Topics: Actinomycetales Infections; Animals; Anti-Bacterial Agents; DNA, Bacterial; Dose-Response Relationship, Drug; Drug Resistance, Bacterial; Horse Diseases; Horses; Microbial Sensitivity Tests; Point Mutation; Rhodococcus equi; Rifampin

To determine the prevalence of antimicrobial resistance to macrolide antimicrobials or rifampin in Rhodococcus equi isolates and to describe treatment outcome in foals infected with antimicrobial-resistant isolates of R equi.. Cross-sectional study.. 38 isolates classified as resistant to macrolide antimicrobials or rifampin received from 9 veterinary diagnostic laboratories between January 1997 and December 2008.. For each isolate, the minimum inhibitory concentration of macrolide antimicrobials (ie, azithromycin, erythromycin, and clarithromycin) and rifampin was determined by use of a concentration-gradient test. Prevalence of R equi isolates from Florida and Texas resistant to macrolide antimicrobials or rifampin was determined. Outcome of antimicrobial treatment in foals infected with antimicrobial-resistant isolates of R equi was determined.. Only 24 of 38 (63.2%) isolates were resistant to >or= 1 antimicrobial. Two isolates were resistant only to rifampin, whereas 22 isolates were resistant to azithromycin, erythromycin, clarithromycin, and rifampin. The overall prevalence of antimicrobial-resistant isolates in submissions received from Florida and Texas was 3.7% (12/328). The survival proportion of foals infected with resistant R equi isolates (2/8 [25.0%]) was significantly less, compared with the survival proportion in foals that received the same antimicrobial treatment from which antimicrobial-susceptible isolates were cultured (55/79 [69.6%]). Odds of nonsurvival for foals infected with resistant R equi isolates were 6.9 (95% confidence interval, 1.3 to 37) times the odds for foals infected with susceptible isolates.. Interpretation of the results emphasized the importance of microbiological culture and antimicrobial susceptibility testing in foals with pneumonia caused by R equi.

Topics: Actinomycetales Infections; Animals; Anti-Bacterial Agents; Drug Resistance, Bacterial; Horse Diseases; Horses; Macrolides; Microbial Sensitivity Tests; Rhodococcus equi; Rifampin; Treatment Outcome; Virulence

We report the case of a 64-year-old male patient with a prosthetic aortic valve who presented with clinical features of endocarditis confirmed by transoesophageal echocardiography. His blood cultures were positive for a very rare and newly described organism-Kytococcus schroeteri. The patient underwent aortic valve replacement and a 6-week course of intravenous antibiotics. This is the fifth reported case of endocarditis associated with this organism.

Topics: Actinomycetales; Actinomycetales Infections; Anti-Bacterial Agents; Aortic Valve; Drug Therapy, Combination; Endocarditis, Bacterial; Gentamicins; Heart Valve Diseases; Humans; Male; Middle Aged; Prosthesis-Related Infections; Rifampin; Vancomycin

In this report, a renal transplant recipient with Rhodococcus lung abscess is described. A high clinical suspicion and appropriate combination antibiotic therapy obviated the need for surgical intervention and was associated with a good clinical outcome. The optimal regimen of combination antibiotic therapy is discussed.

Topics: Actinomycetales Infections; Adult; Anti-Bacterial Agents; Drug Therapy, Combination; Humans; Kidney Transplantation; Lung Abscess; Male; Meropenem; Radiography; Rhodococcus equi; Rifampin; Sirolimus; Thienamycins; Treatment Outcome; Vancomycin

Opportunistic infections contribute to morbidity and mortality of patients undergoing hematopoietic stem cell transplantation and treatment for malignancies. Rothia mucilaginosa, a gram-positive bacterium, is responsible for rare, but often fatal meningitis in severely immunocompromised patients. We describe two cases of meningitis from discrete strains of R. mucilaginosa on our pediatric bone marrow transplant unit, summarize the published cases of R. mucilaginosa meningitis in oncology and stem cell transplant patients, and provide updated recommendations regarding the use of antibiotic therapy in this patient population.

Topics: Actinomycetales Infections; Adolescent; Anti-Bacterial Agents; Ceftazidime; Cerebrospinal Fluid Shunts; Child; Cord Blood Stem Cell Transplantation; Drug Therapy, Combination; Fatal Outcome; Female; Humans; Immunocompromised Host; Leukemia, Megakaryoblastic, Acute; Male; Meningitis, Bacterial; Meropenem; Micrococcaceae; Opportunistic Infections; Postoperative Complications; Rifampin; Sepsis; Thienamycins; Vancomycin

In this report, we describe a case of Rhodococcus equi lung infection diagnosed in an allogeneic hematopoietic stem cell transplant with oral graft-versus-host disease 3 months after stem cell infusion. The lung lesion persisted despite an approximate 3 months of vancomycin therapy, but then responded favorably to a combination of intravenous ertapenem at 1 g daily and oral rifampin at 600 mg daily for 1 month. An overview of Rhodococcus infection in transplant recipients is presented. This case and the discussed literature suggest that combination antibiotic therapy is warranted in patients with decreased humoral and cellular immunity.

Topics: Actinomycetales Infections; Anti-Bacterial Agents; beta-Lactams; Drug Therapy, Combination; Ertapenem; Graft vs Host Disease; Hematopoietic Stem Cell Transplantation; Humans; Lung Diseases; Male; Middle Aged; Radiography; Rhodococcus equi; Rifampin; Transplantation, Homologous

Kytoccoccus schroeteri is an emerging pathogen found mainly in association with prosthetic valve endocarditis. A striking aspect of this species is its resistance to penicillins, including isoxazolylpenicillins, making glycopeptide administration and valve replacement the treatment of choice. We present the case of a 38-year-old female diabetic patient with fever up to 39.1 degrees C for two months. Infection of her prosthetic aortic valve was suspected clinically. Repeated blood cultures revealed growth of K. schroeteri. Transesophageal echocardiography demonstrated a vegetation on the prosthetic aortic valve. Antibiotic treatment with vancomycin, rifampin and gentamicin was started and this regimen led to complete resolution of symptoms and disappearance of the vegetation. It is of particular interest that the patient recovered without further surgical procedures. Since the first description of K. schroeteri in 2002, four cases of endocarditis have been published, suggesting antecedent and continuing underdiagnosis.

Topics: Actinomycetales; Actinomycetales Infections; Adult; Aortic Valve Insufficiency; DNA, Bacterial; Drug Administration Schedule; Drug Resistance, Multiple, Bacterial; Drug Therapy, Combination; Echocardiography, Transesophageal; Endocarditis, Bacterial; Female; Gentamicins; Heart Valve Prosthesis; Humans; Microbial Sensitivity Tests; Ofloxacin; Polymerase Chain Reaction; Rifampin; Vancomycin

Topics: Abscess; Actinomycetales Infections; Animals; Anti-Bacterial Agents; Azithromycin; Diagnosis, Differential; Horse Diseases; Horses; Lung; Male; Pneumonia, Bacterial; Radiography, Thoracic; Rhodococcus equi; Rifampin; Ultrasonography

Cellulosimicrobium cellulans (formerly known as Oerskovia xanthineolytica) rarely causes human infection. Infections have been reported in immunocompromised hosts or in patients with foreign bodies, such as catheters, where treatment has generally involved removal of the foreign body. We report on a case in which the organism was isolated in multiple blood cultures from a 13-year-old male. After initial therapy failed, treatment with vancomycin and rifampin resulted in infection clearance without removal of the central venous catheter.

Topics: Actinomycetales; Actinomycetales Infections; Adolescent; Anti-Bacterial Agents; Bacteremia; Blood; Catheterization, Central Venous; Catheters, Indwelling; Drug Therapy, Combination; Humans; Male; Rifampin; Vancomycin

A 1-year-old neutered male domestic shorthair cat had an ulcerated, proliferative lesion in the submandibular area that did not respond to antibiotic therapy. Impression smears from the mass revealed septic pyogranulomatous inflammation, with large numbers of pleomorphic bacteria observed intracellularly within macrophages as well as neutrophils. Bacterial culture was consistent with a diagnosis of Rhodococcus equi, a facultative intracellular coccobacillus capable of replicating within macrophages. The cat's lesion resolved after treatment with rifampin and clarithromycin. R equi should be considered as a differential diagnosis when coccobacilli are recognized within macrophages in cytologic samples.

Topics: Actinomycetales Infections; Animals; Anti-Bacterial Agents; Cat Diseases; Cats; Clarithromycin; Male; Rhodococcus equi; Rifampin; Treatment Outcome

Rhodococcus equi, a bacterium present in soil, is a common cause of pneumonia in foals. This organism has been recognized as an opportunistic pathogen in humans, typically causing infection in immunocompromised hosts such as HIV-infected patients and organ transplant recipients. However, human infection with R. equi has not been reported in Japan except in a case involving a laboratory worker. We report the first human case of VapB-positive R. equi pneumonia, which involved an HIV-infected patient living in an urban area in Japan. The patient was treated successfully with 450 mg rifampicin and 600 mg tosufloxacin, even though his CD4+ lymphocyte count at the time of diagnosis was 10/microl. The patient's dogs were suspected in the epidemiology of this infection, but unfortunately we could not isolate the organism from canine-associated specimens in this case. R. equi infections in companion animals have been thought to be very rare, but they may be increasing in dogs. Therefore, further epidemiological research may clarify the prevalence of R. equi infection and the factors predisposing dogs to this infection.

Topics: Actinomycetales Infections; AIDS-Related Opportunistic Infections; Animals; Anti-Bacterial Agents; CD4 Lymphocyte Count; Diagnosis, Differential; Dogs; Fluoroquinolones; Humans; Male; Microbial Sensitivity Tests; Middle Aged; Naphthyridines; Rhodococcus equi; Rifampin; Tomography, X-Ray Computed

A 3-month-old female Arabian horse was evaluated because of fever, respiratory distress, lethargy, and decreased appetite of 5 days' duration. Pleural effusion was diagnosed on the basis of ultrasonographic and radiographic examinations. Cytologic examination of pleural fluid collected via thoracocentesis revealed septic inflammation; bacteriologic culture of a sample of that fluid yielded Rhodococcus equi. A large intra-abdominal mass adjacent to the body wall was identified ultrasonographically. A specimen of the mass was collected via aspiration; the specimen was identified cytologically as purulent exudate that contained large numbers of rod-shaped bacteria, which confirmed abdominal abscess formation. Bacteriologic culture of a sample of the exudate also yielded R. equi. The foal was treated with azithromycin (10 mg/kg [4.5 mg/lb], PO, q 24 h for 5 days then q 48 h) and rifampin (5 mg/kg [2.3 mg/lb], PO, q 12 h) for 8 weeks and metronidazole (15 mg/kg [6.8 mg/lb], PO, q 8 h) for 3 weeks. Clinically, the foal responded to antimicrobial treatment within 2 weeks. At 8 weeks after the initial evaluation, ultrasonographic examination of the foal revealed resolution of the pleural effusion and abdominal abscess. In foals, R. equi infection typically results in pyogranulomatous pneumonia, and pleural effusion is an uncommon clinical sign. The combination of azithromycin and rifampin appears to be an effective treatment for R. equi infection in foals.

Topics: Abdominal Abscess; Actinomycetales Infections; Animals; Animals, Newborn; Anti-Bacterial Agents; Azithromycin; Drug Resistance, Bacterial; Female; Horse Diseases; Horses; Pneumonia, Bacterial; Rhodococcus equi; Rifampin; Treatment Outcome; Ultrasonography

The antimicrobial susceptibilities of 30 Rhodococcus equi isolates obtained from 30 patients between 1993 and 2001 in northern Thailand were investigated. The MICs showed a tendency toward resistance to various antibiotics but sensitivity to imipenem, minocycline, vancomycin, and teicoplanin (MICs, /=64 micro g/ml) to rifampin. PCR amplification and DNA sequencing of the rpoB gene and molecular typing by pulsed-field gel electrophoresis (PFGE) were performed for eight R. equi isolates from eight AIDS patients with pneumonia or lung abscess caused by R. equi between 1998 and 2001, including one low- and three high-level rifampin-resistant isolates. As a result, two high-level rifampin-resistant strains with PFGE pattern A had a Ser531Trp (Escherichia coli numbering) mutation, and one high-level rifampin-resistant strain with PFGE pattern B had a His526Tyr mutation, whereas one low-level rifampin-resistant strain with PFGE pattern C had a Ser509Pro mutation. Four rifampin-susceptible strains with PFGE patterns D and E showed an absence of mutation in the rpoB region. Our results indicate the presence of several types of rifampin-resistant R. equi strains among AIDS patients in northern Thailand.

Topics: Actinomycetales Infections; Adult; AIDS-Related Opportunistic Infections; Animals; Antibiotics, Antitubercular; DNA-Directed RNA Polymerases; Drug Resistance, Bacterial; Female; Humans; Lung Abscess; Male; Microbial Sensitivity Tests; Mutation; Pneumonia, Bacterial; Rhodococcus equi; Rifampin; Thailand

Topics: Actinomycetales Infections; Adult; AIDS-Related Opportunistic Infections; Anti-Bacterial Agents; Anti-Infective Agents; Drug Therapy, Combination; HIV Infections; Humans; Levofloxacin; Lung Diseases; Male; Ofloxacin; Rhodococcus equi; Rifampin

The Rhodococcus equi is an aerobic gram positive pleomorphic bacillus, that was isolated for the first time like a producer of bronchopneumonia in young horses. Every time more often, it is being recognized as a pathogen in humans, mainly in the immunodepressed population. We described a case, until now exceptional, of laryngeal infection by Rhodococcus equi in a patient with positive serology for the virus of the human immunodeficiency (HIV), and we reviewed some clinical and epidemiological characteristics of the infections by this germ. The treatment is riphampicine and/or erythromycin, being the prognosis bad, because usually they are immunodepressed patients.

Topics: Acquired Immunodeficiency Syndrome; Actinomycetales Infections; Adult; Anti-Bacterial Agents; Antibiotics, Antitubercular; Drug Therapy, Combination; Erythromycin; Humans; Laryngeal Mucosa; Laryngitis; Male; Rhodococcus equi; Rifampin

A case of chronic scalp wound infection due to Rhodococcus equi in an immunocompetent individual following heavily contaminated traumatic injury was successfully treated by combining antibiotics and surgery. The agents used were erythromycin and rifampicin.

Topics: Actinomycetales Infections; Adolescent; Anti-Bacterial Agents; Antibiotics, Antitubercular; Erythromycin; Humans; Immunocompetence; Male; Rhodococcus equi; Rifampin; Scalp; Wound Infection

Treatment with a combination of erythromycin and rifampin has considerably improved survival rates of foals and immunocompromised patients suffering from severe pneumonia caused by Rhodococcus equi. Frequently, because of monotherapy, emergence of rifampin-resistant strains has been responsible for treatment failure. Using consensus oligonucleotides, we have amplified and sequenced the rifampin resistance (Rif(r))-determining regions of 12 rifampin-resistant R. equi strains isolated from three foals and of mutants selected in vitro from R. equi ATCC 3701, a rifampin-susceptible strain. The deduced amino acid sequences compared to those of four rifampin-susceptible R. equi strains showed several types of mutations. In 3 of the 10 strains isolated from one foal, His526Asn (Escherichia coli numbering) and Asp516Val mutations were associated with low-level resistance (rifampin MIC, 2 to 8 microg/ml), whereas His526Asp conferred high-level resistance (rifampin MIC, 128 microg/ml) in the 7 remaining strains. In strains from the two other foals, His526Asp and Ser531Leu mutations were found to be associated with high-level and low-level resistance, respectively. The in vitro mutants, highly resistant to rifampin, harbored His526Tyr and His526Arg substitutions. As described in other bacterial genera, His526, Ser531, and Asp516 are critical residues for rifampin resistance in R. equi, and the resistance levels are dependent on both the location and the nature of the substitution.

Topics: Actinomycetales Infections; Animals; Antibiotics, Antitubercular; DNA-Directed RNA Polymerases; Drug Resistance, Bacterial; Horse Diseases; Horses; Microbial Sensitivity Tests; Mutation; Pneumonia, Bacterial; Rhodococcus equi; Rifampin; Sequence Analysis, DNA

Diagnosis of pneumonia caused by Rhodococcus equi can be made more rapidly by use of a polymerase chain reaction (PCR) assay than by use of conventional bacteriologic culture techniques. Use of a PCR assay aids in the differentiation between virulent and avirulent strains of R equi, and the assay may be used to identify R equi in feces and soil of breeding farms.

Topics: Actinomycetales Infections; Animals; Anti-Bacterial Agents; Antibiotics, Antitubercular; Erythromycin; Female; Gentamicins; Horse Diseases; Horses; Leukocyte Count; Penicillins; Platelet Count; Pneumonia, Bacterial; Polymerase Chain Reaction; Radiography, Thoracic; Rhodococcus equi; Rifampin; Virulence

Topics: Actinomycetales Infections; AIDS-Related Opportunistic Infections; Colonic Polyps; Drug Therapy, Combination; Humans; Lung; Male; Middle Aged; Rhodococcus equi; Rifampin; Vancomycin

In Sweden, mares sometimes develop acute, often fatal, colitis when their foals are treated orally with erythromycin and rifampicin for Rhodococcus (R.) equi infection. Clostridium (C.) difficile, or its cytotoxin, was demonstrated in faecal samples from 5 of 11 (45%) mares with diarrhoea. By contrast C. difficile was not found in the faecal flora of 12 healthy mares with foals treated for R. equi infection or in 56 healthy mares with healthy untreated foals. No other enteric pathogen was isolated from any diarrhoeic mare. Of 7 investigated treated foals, 4 had a high (1651.0, 1468.3, 273.0 and 88.8 microg/g) faecal concentration of erythromycin. The dams of those 4 foals developed acute colitis, whereas the dams of 3 foals with a lower (26.3, 4.6 and 3.7 microg/g) faecal erythromycin concentration remained healthy, indicating that there might have been an accidental intake of erythromycin by mares. The foals treated with antibiotics were regarded as asymptomatic carriers and potential reservoirs, as C. difficile was found in 7 of 16 foals investigated, while 56 untreated foals proved negative. The isolated C. difficile strains proved resistant to both erythromycin (MIC>256 mg/l) and rifampicin (MIC>32 mg/l), a fact that may have favoured the growth of C. difficile in the foal intestine. All mares found positive for C. difficile were, or had recently been, hospitalised together with their foals, indicating that C. difficile may be a nosocomial infection, in horses. The results emphasise that routine testing for C. difficile and its cytotoxin is recommended when acute colitis occurs in mares when their foals are treated with erythromycin and rifampicin. Preventive measures in order to avoid accidental ingestion of erythromycin by mares from the treatment of their foals are suggested.

Topics: Actinomycetales Infections; Acute Disease; Animals; Animals, Suckling; Anti-Bacterial Agents; Bacterial Proteins; Bacterial Toxins; Clostridioides difficile; Cytotoxins; Drug Resistance, Microbial; Drug Therapy, Combination; Enterocolitis, Pseudomembranous; Erythromycin; Feces; Female; Horse Diseases; Horses; Pneumonia, Bacterial; Rhodococcus equi; Rifampin

In Sweden there are several reports of mares developing acute colitis while their foals were being treated orally for Rhodococcus equi pneumonia with the combination of erythromycin and rifampicin. In this study 6 adult horses were given low oral dosages of these antibiotics, singly or in combination. Within 3 days post administration of erythromycin, in one case in combination with rifampicin, 2 horses developed severe colitis (one fatal). Clostridium difficile was isolated from one of the horses, whereas no specific pathogens were isolated from the other. Both horses had typical changes in blood parameters seen in acute colitis. Clostridium difficile was also isolated from the faeces of a third horse given an even lower dosage of erythromycin in combination with rifampicin. This horse developed very mild clinical symptoms and recovered spontaneously. In the fourth horse given erythromycin only, very high numbers of Clostridium perfringens were isolated. The horses given rifampicin only did not develop any clinical symptoms and there were no major changes in their faecal flora. In conclusion, it has been demonstrated that low dosages of erythromycin ethylsuccinate can induce severe colitis in horses associated with major changes of the intestinal microflora. Clostridium difficile has been demonstrated as a potential aetiological agent in antibiotic-induced acute colitis.

Topics: Actinomycetales Infections; Acute Disease; Animals; Animals, Suckling; Anti-Bacterial Agents; Clostridioides difficile; Enterocolitis, Pseudomembranous; Erythromycin Ethylsuccinate; Feces; Female; Horse Diseases; Horses; Male; Rhodococcus equi; Rifampin; Sweden

Topics: Actinomycetales Infections; Adult; AIDS-Related Opportunistic Infections; Ciprofloxacin; Clarithromycin; Diagnostic Errors; Drug Therapy, Combination; Humans; Mycobacterium Infections; Pneumonia, Bacterial; Rhodococcus equi; Rifampin; Vancomycin

To investigate the emergence of rifampin resistance in Rhodococcus equi strains isolated from foals and their environment in Japan, we compared the in vitro antimicrobial susceptibilities to rifampin of 640 isolates from 64 infected foals and 98 soil isolates from their horse-breeding farms. As a control, 39 human isolates from patients with and without AIDS were also tested for susceptibility to rifampin. All of the isolates showed rifampin sensitivity, except isolates from one infected foal and two patients with AIDS that showed rifampin resistance. To investigate the emergence of rifampin-resistant R. equi in the infected foal, which had received rifampin monotherapy for a month before euthanasia, 99 isolates of R. equi from the lesions and 20 isolates from the intestinal contents of the one foal with rifampin-resistant organisms were analyzed for rifampin susceptibilities, pathogenicities, and ribotypes. Of the 99 isolates from the lesions, all of which were virulent R. equi strains containing a virulence plasmid with a size of 85 or 90 kb, 90 (91%) isolates were rifampin resistant (MIC, > or = 12.5 microg/ml). On the other hand, of the 20 isolates from the intestinal contents, 11 (55%) isolates showed rifampin resistance (MIC, > or = 25 microg/ml), and 5 of them were avirulent R. equi strains. Among these 101 rifampin-resistant R. equi isolates with and without virulence plasmids characterized by ribotyping, 58 were type I, 20 were type II, 11 were type III, and 12 were type IV. These results demonstrated that at least eight different rifampin-resistant R. equi strains emerged concurrently and respectively from the different lesions and intestinal contents of the infected foal.

Topics: Actinomycetales Infections; Animals; Antibiotics, Antitubercular; Drug Resistance, Microbial; Horse Diseases; Horses; Humans; Japan; Microbial Sensitivity Tests; Rhodococcus equi; Rifampin

Rhodococcus equi, formerly known as Corynebacterium equi, an aerobic, gram-positive, pleomorphic coccobacillus, is a well-known pathogen for domestic livestock. We present a biopsy- and culture-proven case of Rhodococcus equi brain abscesses in a patient seropositive for HIV, having an appearance not described previously.

Topics: Actinomycetales Infections; Adult; AIDS-Related Opportunistic Infections; Drug Therapy, Combination; Epilepsy, Tonic-Clonic; Humans; Imipenem; Male; Rhodococcus equi; Rifampin; Tomography, X-Ray Computed

Topics: Actinomycetales Infections; Adult; AIDS-Related Opportunistic Infections; Ciprofloxacin; Clarithromycin; Drug Resistance, Microbial; Drug Resistance, Multiple; Drug Therapy, Combination; Erythromycin; Gentamicins; Humans; Male; Microbial Sensitivity Tests; Pneumonia, Bacterial; Rhodococcus equi; Rifampin; Vancomycin

Topics: Actinomycetales Infections; Animals; Animals, Newborn; Anti-Bacterial Agents; Antibiotics, Antitubercular; Bronchopneumonia; Drug Synergism; Drug Therapy, Combination; Erythromycin; Horse Diseases; Horses; Rhodococcus equi; Rifampin; Saskatchewan

Infections of Rhodococcus equi, a well-known pathogen in animals which causes cavitated pneumonia similar to that caused by mycobacteria, were studied in three HIV-infected patients. This microorganism was isolated in the bronchoalveolar washings of two patients and in the sputum of the third. In two patients, Rh. equi represented the first clinical opportunistic manifestation of HIV disease. One patient died of concomitant Pneumocystis infection. The eradication of the microorganism occurred in two out of three patients. It was found that no isolates were resistant to erythromycin, claritromycin, rifampin, vancomycin, teicoplanin, imipenem, gentamycin or azithromycin (MIC values < or = 0.1 microgram/ml). Moreover, the quinolones (ciprofloxacin and ofloxacin) were found to be less effective, whereas neither the beta-lactam antibiotics nor chloramphenicol were effective therapy for this microrganism. At least two antimicrobial agents should be given contemporaneously to treat these infections for a period of up to several months. Our results suggest that the combinations erythromycin + rifampin or imipenem + teicoplanin are the most effective treatments in Rh. equi infections.

Topics: Actinomycetales Infections; Adult; AIDS-Related Opportunistic Infections; Anti-Bacterial Agents; Azithromycin; Bacteremia; Bronchoalveolar Lavage Fluid; Clarithromycin; Drug Resistance, Microbial; Drug Synergism; Drug Therapy, Combination; Erythromycin; Female; Gentamicins; HIV Infections; Humans; Imipenem; Male; Pleurisy; Pneumonia, Bacterial; Rhodococcus equi; Rifampin; Sputum; Teicoplanin; Vancomycin

In three patients, men of 30, 21 and 24 years old respectively, Rhodococcus equi pneumonia was diagnosed. Antibiotic treatment, followed by secondary prophylaxis, was successful. In one patient, lobectomy was done. R. equi, a well-known bacterial pathogen in horses, appears also to be pathogenic in humans in case of immunodeficiency.

Topics: Actinomycetales Infections; Adult; AIDS-Related Opportunistic Infections; Drug Therapy, Combination; Erythromycin; Humans; Immunocompromised Host; Male; Pneumonia, Bacterial; Rhodococcus equi; Rifampin

Topics: Acquired Immunodeficiency Syndrome; Actinomycetales Infections; Adult; Clarithromycin; Erythromycin; Humans; Imipenem; Male; Middle Aged; Pneumonia; Rhodococcus equi; Rifampin; Vancomycin

Topics: Actinomycetales Infections; Animals; Anti-Bacterial Agents; Antibiotics, Antitubercular; Arthritis, Reactive; Drug Resistance, Microbial; Drug Therapy, Combination; Erythromycin; Female; Horse Diseases; Horses; Lung; Pneumonia, Bacterial; Rheumatoid Factor; Rhodococcus equi; Rifampin; Synovial Fluid

Twenty-four foals were confirmed to be infected with Rhodococcus equi on a private stud in Zimbabwe over a two-year period. Six mares had foals which were affected in each of the two years. All the foals were febrile and early cases were detected by this pyrexia. Bronchopneumonia was only clinically detectable in advanced cases. In spite of energetic hygiene measures relating to pasture and housing management, the incidence was higher in the second year (23 per cent of foals born) than in the first (15 per cent of foals born). The mean age of the foals was significantly greater in the second year. The immunological status of some of the foals was obtained from zinc sulphate turbidity tests performed at 24 hours old and all the affected foals so tested were considered to have had effective colostral transfer. Clinically, affected foals showed pyrexia, tachypnoea and tachycardia and many had a scanty purulent nasal discharge. Only one animal had diarrhoea which was attributed to enteric infection with R equi. Diagnosis was confirmed by clinical examination, culture of the organism from tracheal aspirates and thoracic radiography and was supported by significant elevations of plasma fibrinogen and platelet and neutrophil counts in all cases. Anaemia was not a major finding in any case. Rifampicin and erythromycin were administered per os and weight-related doses were continued until plasma fibrinogen and the absolute neutrophil and platelet counts had been persistently normal for two weeks. Supportive radiography was obtained in some cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Actinomycetales Infections; Animals; Animals, Newborn; Disease Outbreaks; Erythromycin; Female; Horse Diseases; Horses; Rhodococcus equi; Rifampin; Zimbabwe

Topics: Actinomycetales Infections; Drug Therapy, Combination; Erythromycin; HIV Infections; HIV-1; Humans; Mycobacterium Infections; Rhodococcus equi; Rifampin

Topics: 4-Quinolones; Actinomycetales Infections; Adult; Anti-Infective Agents; Drug Resistance, Microbial; HIV Infections; Humans; Malacoplakia; Male; Opportunistic Infections; Rhodococcus equi; Rifampin

Topics: Actinomycetales Infections; Adult; AIDS-Related Opportunistic Infections; Anti-Bacterial Agents; Erythromycin; Humans; Lung Diseases; Male; Rhodococcus equi; Rifampin

Topics: Actinomycetales Infections; Adult; Ciprofloxacin; Drug Resistance, Microbial; HIV Infections; Humans; Lung Abscess; Male; Rhodococcus equi; Rifampin

Topics: Acquired Immunodeficiency Syndrome; Actinomycetales Infections; Adult; Anti-Bacterial Agents; Drug Resistance, Microbial; Humans; Male; Pneumonia; Recurrence; Rhodococcus equi; Rifampin

The in vitro susceptibility of nine Rhodococcus equi strains (seven isolates from immunocompromised patients mainly HIV positive and two reference strains) to twenty various antibiotics were assessed for bacteriostatic effects by an agar dilution method. Imipenem and ceftriaxone were the most effective of the beta-lactams studied. The lowest MIC were noted with vancomycin, teicoplanin, erythromycin, clarithromycin, rifampicin, gentamicin and doxycycline. A longitudinal survey, including three strains isolated from the same patient, showed the emergence of rifampicin resistance and a marked increase of the MIC to imipenem.

Topics: Actinomycetales Infections; Aminoglycosides; Anti-Bacterial Agents; Dose-Response Relationship, Drug; Doxycycline; Drug Resistance, Microbial; HIV Infections; Humans; In Vitro Techniques; Lactams; Macrolides; Opportunistic Infections; Quinolones; Rhodococcus; Rifampin

We report a case of lung infection, clinically resembling tuberculosis, caused by Rhodococcus rubropertinctus. The patient had no apparent immunosuppression which is unusual for disease caused by the 'rhodochrous' complex. The infection responded successfully to oral anti-tuberculous therapy, which included rifampicin, and to oral tetracycline.

Topics: Actinomycetales Infections; Administration, Oral; Australia; Female; Humans; Lung Diseases; Rhodococcus; Rifampin; Tetracycline; Vietnam

Topics: Actinomycetales Infections; Anaerobiosis; Anti-Bacterial Agents; Bacterial Infections; Bacteroides Infections; Cephalosporins; Chloramphenicol; Clindamycin; Clostridium Infections; Erythromycin; Fusobacterium; Humans; Lincomycin; Metronidazole; Microbial Sensitivity Tests; Oxygen; Penicillins; Rifampin; Streptococcal Infections; Tetracycline; Treponemal Infections; Vancomycin; Veillonella