rifampin and Gram-Negative-Bacterial-Infections

The increasing prevalence of infections with multidrug-resistant (MDR), extensively-drug resistant (XDR) or difficult-to-treat drug resistant (DTR) Gram-negative bacilli (GNB), including Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae, Enterobacter species, and Escherichia coli poses a severe challenge.. The rapid growing of multi-resistant GNB as well as the considerable deceleration in development of new anti-infective agents have made polymyxins (e.g. polymyxin B and colistin) a mainstay in clinical practices as either monotherapy or combination therapy. However, whether the polymyxin-based combinations lead to better outcomes remains unknown. This review mainly focuses on the effect of polymyxin combination therapy versus monotherapy on treating GNB-related infections. We also provide several factors in designing studies and their impact on optimizing polymyxin combinations.. An abundance of recent in vitro and preclinical in vivo data suggest clinical benefit for polymyxin-drug combination therapies, especially colistin plus meropenem and colistin plus rifampicin, with synergistic killing against MDR, XDR, and DTR P. aeruginosa, K. pneumoniae and A. baumannii. The beneficial effects of polymyxin-drug combinations (e.g. colistin or polymyxin B + carbapenem against carbapenem-resistant K. pneumoniae and carbapenem-resistant A. baumannii, polymyxin B + carbapenem + rifampin against carbapenem-resistant K. pneumoniae, and colistin + ceftolozan/tazobactam + rifampin against PDR-P. aeruginosa) have often been shown in clinical setting by retrospective studies. However, high-certainty evidence from large randomized controlled trials is necessary. These clinical trials should incorporate careful attention to patient's sample size, characteristics of patient's groups, PK/PD relationships and dosing, rapid detection of resistance, MIC determinations, and therapeutic drug monitoring.

Topics: Anti-Bacterial Agents; Anti-Infective Agents; Carbapenems; Colistin; Drug Resistance, Multiple, Bacterial; Gram-Negative Bacteria; Gram-Negative Bacterial Infections; Humans; Microbial Sensitivity Tests; Polymyxin B; Polymyxins; Retrospective Studies; Rifampin

The superiority of combination therapy for carbapenem-resistant Gram-negative bacilli (CR-GNB) infections remains controversial. In vitro models may predict the efficacy of antibiotic regimens against CR-GNB. A systematic review and meta-analysis was performed including pharmacokinetic/pharmacodynamic (PK/PD) and time-kill (TK) studies examining the in vitro efficacy of antibiotic combinations against CR-GNB [PROSPERO registration no. CRD42019128104]. The primary outcome was in vitro synergy based on the effect size (ES): high, ES ≥ 0.75, moderate, 0.35 < ES < 0.75; low, ES ≤ 0.35; and absent, ES = 0). A network meta-analysis assessed the bactericidal effect and re-growth rate (secondary outcomes). An adapted version of the ToxRTool was used for risk-of-bias assessment. Over 180 combination regimens from 136 studies were included. The most frequently analysed classes were polymyxins and carbapenems. Limited data were available for ceftazidime/avibactam, ceftolozane/tazobactam and imipenem/relebactam. High or moderate synergism was shown for polymyxin/rifampicin against Acinetobacter baumannii [ES = 0.91, 95% confidence interval (CI) 0.44-1.00], polymyxin/fosfomycin against Klebsiella pneumoniae (ES = 1.00, 95% CI 0.66-1.00) and imipenem/amikacin against Pseudomonas aeruginosa (ES = 1.00, 95% CI 0.21-1.00). Compared with monotherapy, increased bactericidal activity and lower re-growth rates were reported for colistin/fosfomycin and polymyxin/rifampicin in K. pneumoniae and for imipenem/amikacin or imipenem/tobramycin against P. aeruginosa. High quality was documented for 65% and 53% of PK/PD and TK studies, respectively. Well-designed in vitro studies should be encouraged to guide the selection of combination therapies in clinical trials and to improve the armamentarium against carbapenem-resistant bacteria.

Topics: Amikacin; Anti-Bacterial Agents; Azabicyclo Compounds; Carbapenems; Ceftazidime; Cephalosporins; Colistin; Drug Combinations; Drug Resistance, Bacterial; Drug Synergism; Drug Therapy, Combination; Fosfomycin; Gram-Negative Bacteria; Gram-Negative Bacterial Infections; Humans; Imipenem; In Vitro Techniques; Microbial Sensitivity Tests; Polymyxins; Rifampin; Tazobactam; Tobramycin

Prosthetic joint infection (PJI) is a serious complication of arthroplasty that is associated with significant mortality, morbidity and costs. PJI is difficult to cure because causative bacteria form and persist in biofilm adherent to the prosthesis surface. PJI can be classified into early, delayed or late according to the time of onset after insertion of the prosthesis, and this classification can help determine pathogenesis and appropriate management. Traditional treatment has been with prolonged intravenous antibiotics and prosthesis exchange, which has been successful in treating infection but is technically difficult and has high rates of associated morbidity. On the basis of in vitro and animal studies, interest has turned to the use of antimicrobials that are particularly active against biofilm-associated bacteria. Recent clinical evidence shows success in more than 77% of early PJI with surgical debridement, retention of prosthesis and the use of rifampicin-based combinations for staphylococcal PJI. Fluoroquinolones are preferred for Gram-negative PJI. Optimal antimicrobial treatment duration and the management of polymicrobial, enterococcal, fungal and culture-negative infections are still yet to be defined but will become more clear as the results of current research comes to hand.

Topics: Anti-Bacterial Agents; Arthroplasty; Australia; Biofilms; Debridement; Device Removal; Drug Administration Schedule; Drug Therapy, Combination; Fluoroquinolones; Gram-Negative Bacterial Infections; Humans; Prosthesis-Related Infections; Reoperation; Rifampin; Staphylococcal Infections

Multidrug-resistant (MDR) gram-negative bacterial infections are associated with high morbidity and mortality. Given the lack of availability of new highly effective antimicrobial drugs against multiresistant strains, combination regimens are administered that include rifampicin for its demonstrated in vitro synergism with multiple drugs. A literature review was performed of clinical studies reporting the use of rifampicin in the treatment of MDR gram-negative bacterial infections. Nineteen studies were found, including only one randomised controlled study. Data in the literature on combined therapeutic regimens with rifampicin are limited and refer mostly to uncontrolled studies. Therefore, the real clinical benefit of using rifampicin-containing therapies for the treatment of gram-negative multiresistant bacteria in terms of clinical outcome and survival rates still needs to be assessed.

Topics: Anti-Bacterial Agents; Drug Resistance, Multiple, Bacterial; Drug Therapy, Combination; Gram-Negative Bacterial Infections; Humans; Randomized Controlled Trials as Topic; Rifampin; Survival Analysis; Treatment Outcome

Flavobacterium meningosepticum is an unusual, highly resistant, gram-negative bacillus that is associated with neonatal meningitis and nursery outbreaks of meningitis. The optimal therapy for this infection is not known. We successfully treated three neonates with intravenous vancomycin and rifampin. We determined the in vitro activity of meropenem, ciprofloxacin, vancomycin, linezolid (PNU-100766), and rifampin, alone and in combination, against four isolates of F. meningosepticum from neonates with sepsis and meningitis. MICs were determined by tube dilution, and fractional inhibitory concentrations were calculated with use of the checkerboard microtiter dilution technique. Synergy was observed between rifampin and vancomycin against three isolates, while combinations of vancomycin, ciprofloxacin, and linezolid showed an additive effect against all isolates. These results support the clinical evidence that the combination of vancomycin and rifampin is an appropriate regimen for neonatal meningitis due to F. meningosepticum. The combination of meropenem and vancomycin was antagonistic. The clinical efficacy of combinations including ciprofloxacin, newer quinolones, or linezolid for treating F. meningosepticum meningitis deserves further study.

Topics: Drug Synergism; Drug Therapy, Combination; Female; Flavobacterium; Gram-Negative Bacterial Infections; Humans; Infant; Infant, Newborn; Male; Meningitis, Bacterial; Microbial Sensitivity Tests; Rifampin; Vancomycin

Chryseobacterium meningosepticum is a ubiquitous Gram-negative bacillus historically associated with meningitis in premature neonates. We report 15 positive cultures and 6 cases of infection among immunocompromised adults at our institution over a 10-year period and review the English-language literature on C. meningosepticum. Excluding the present series, there are 308 reports of positive cultures in the literature, of which 59% were determined to represent true infections. Sixty-five percent of those infected were younger than 3 months of age. Meningitis was the most common infectious syndrome among neonates, seen in 84% of cases and associated with a 57% mortality rate. Less commonly reported infections among infants included sepsis (13%) and pneumonia (3%). Pneumonia was the most frequent infection among the postneonatal group, accounting for 40% of cases, followed by sepsis (24%), meningitis (18%), endocarditis (3%), cellulitis (3%), abdominal infections (3%), eye infections (3%), and single case reports of sinusitis, bronchitis, and epididymitis. The 6 cases in our series were all adults, with a mean age of 58.7 years. Sites of C. meningosepticum infection were limited to the lungs, bloodstream, and biliary tree. Infection in our series was associated with prolonged hospitalization, prior exposure to multiple antibiotics, and host immunocompromise, particularly neutropenia. C. meningosepticum is resistant to multiple antibiotics, and disk dilution is notoriously unreliable for antibiotic sensitivity testing. Sensitivity testing on the 15 isolates from our institution revealed the most efficacious antibiotics to be minocycline (100% sensitive), rifampin (93%), trimethoprim-sulfamethoxazole (67%), and ciprofloxacin (53%). In contrast to reports in the literature, the isolates in our series displayed widespread resistance to vancomycin (100% resistant or intermediately sensitive), erythromycin (100%), and clindamycin (86%). These findings have important implications for the clinician when choosing empiric antibiotic regimens for patients with risk factors for C. meningosepticum infection.

Topics: Adult; Aged; Anti-Bacterial Agents; Antibiotics, Antitubercular; Breast Neoplasms; Ciprofloxacin; Drug Resistance, Microbial; Female; Flavobacterium; Gram-Negative Bacterial Infections; Humans; Immunocompromised Host; Infant; Infant, Newborn; Leukemia, Myeloid, Acute; Liver Transplantation; Male; Meningitis, Bacterial; Middle Aged; Minocycline; Pneumonia, Bacterial; Rifampin; Sepsis; Trimethoprim, Sulfamethoxazole Drug Combination

Topics: Administration, Oral; Anti-Bacterial Agents; Anti-Infective Agents; Chronic Disease; Drug Therapy, Combination; Fluoroquinolones; Gram-Negative Bacterial Infections; Humans; Osteomyelitis; Rifampin; Staphylococcal Infections; Trimethoprim, Sulfamethoxazole Drug Combination

We tested the efficiency of 2 different antibiotics, rifampicin and oxolinic acid, against an established infection caused by fish pathogen Francisella noatunensis ssp. orientalis (F.n.o.) in zebrafish. The drugs were tested in the free form as well as encapsulated into biodegradable nanoparticles, either polylactic-co-glycolic acid (PLGA) nanoparticles or nanostructured lipid carriers. The most promising therapies were PLGA-rifampicin nanoparticles and free oxolinic acid; the PLGA nanoparticles significantly delayed embryo mortality while free oxolinic acid prevented it. Encapsulation of rifampicin in both PLGA and nanostructured lipid carriers enhanced its efficiency against F.n.o. infection relative to the free drug. We propose that the zebrafish model is a robust, rapid system for initial testing of different treatments of bacterial diseases important for aquaculture.

Topics: Animals; Anti-Bacterial Agents; Fish Diseases; Francisella; Gram-Negative Bacterial Infections; Lactic Acid; Lipids; Nanoparticles; Oxolinic Acid; Polyglycolic Acid; Polylactic Acid-Polyglycolic Acid Copolymer; Rifampin; Zebrafish

We report the structure-activity relationship analyses of 17 linear lipopeptide paenipeptin analogues. Analogues 7, 12, and 17 were more potent than the lead compound. Analogue 17 was active against carbapenem-resistant and polymyxin-resistant pathogens. This compound at 40 μg/mL resulted in 3 log and 2.6 log reductions of methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa, respectively, in catheter-associated biofilms in vitro. Analogue 17 showed little hemolysis at 32 μg/mL and lysed 11% of red blood cells at 64 μg/mL. Analogues 9 and 16 were nonhemolytic and retained potent P. aeruginosa-specific antimicrobial activity. These two analogues when used alone lacked activity against Acinetobacter baumannii and Klebsiella pneumoniae; however, analogue 9 and 16 at 4 μg/mL decreased the MIC of rifampicin and clarithromycin against the same pathogens from 16 to 32 μg/mL to nanomolar levels (sensitization factor: 2048-8192). Therefore, paenipeptins, alone or in combination with rifampicin or clarithromycin, are promising candidates for treating bacterial infections.

Topics: Anti-Bacterial Agents; Biofilms; Clarithromycin; Drug Synergism; Gram-Negative Bacteria; Gram-Negative Bacterial Infections; Hemolysis; Humans; Lipopeptides; Microbial Sensitivity Tests; Paenibacillus; Rifampin; Structure-Activity Relationship

Aeromonas hydrophila, as a strong Gram-negative bacterium, can infect a wide range of freshwater fish, including common carp Cyprinus carpio, and cause the huge economic loss. To create the effective vaccine is the best way to control the outbreak of the disease caused by A. hydrophila. In this study, a live attenuated A. hydrophila strain, XX1LA, was screened from the pathogenic A. hydrophila strain XX1 cultured on medium containing the antibiotic rifampicin, which was used as a live attenuated vaccine candidate. The immune protection of XX1LA against the pathogen A. hydrophila in common carp was evaluated by the relative percent survival (RPS), the specific IgM antibody titers, serum lysozyme activity and the expression profiles of multiple immune-related genes at the different time points following immunization. The results showed that the variable up-regulations of the immune-related genes, such as the pro-inflammatory cytokine IL-1β, the chemokine IL-10 and IgM, were observed in spleen and liver of common carp injected in the vaccines with the formalin-killed A. hydrophila (FKA) and the live attenuated XX1LA. Specific antibody to A. hydrophila was found to gradually increase during 28 days post-vaccination (dpv), and the RPS (83.7%) in fish vaccinated with XX1LA, was significant higher than that (37.2%) in fish vaccinated with FKA (P<0.05) on Day 28 after challenged by pathogen. It was demonstrated that the remarkable immune protection presented in the group vaccinated with XX1LA. During the late stage of 4-week immunization phase, compared with FKA and the control, specific IgM antibody titers significantly increased (P<0.05) in the XX1LA group. The activity of the lysozyme in serum indicated no significant change among three groups. In summary, the live attenuated bacterial vaccine XX1LA, screened in this study, indicates the better protect effect on common carp against A. hydrophila, which can be applied in aquaculture of common carp to prevent from the disease outbreak in the future.

Topics: Aeromonas hydrophila; Animals; Antibodies, Bacterial; Bacterial Vaccines; Carps; Fish Diseases; Gram-Negative Bacterial Infections; Immunoglobulin M; Interleukin-10; Interleukin-1beta; Rifampin; Vaccines, Attenuated

Infections with carbapenem-resistant Gram-negative bacteria (CRGNB) are increasing and are associated with a high mortality. Synergistic effects of combination therapy with a polymyxin, carbapenem, and rifampin have been observed in in vitro studies. Clinical data are limited to retrospective studies.. We performed an observational cohort study of patients over 18 y of age who were treated with polymyxin B combination therapy.. One hundred and four patients were studied. The mean age was 77 y; 73% had recently received antibiotics, 67% had recently been hospitalized, and 47% lived in a nursing facility. The most common infections were pneumonia and urinary tract infection due to Acinetobacter baumannii (33%), Klebsiella pneumoniae (24%), and Pseudomonas aeruginosa (11%). Treatment regimens included polymyxin B with a carbapenem in 48%, with additional rifampin in 23%. Clinical success was achieved in 50% and reinfection occurred in 25%. Treatment-related acute renal failure occurred in 14.4%. No treatment-related hemodialysis was needed. All-cause hospital mortality was 47% and mortality after 6 months was 77%. No significant difference was found between treatment regimens. Age (odds ratio (OR) 10.4 per 10 y, p = 0.04), severity of acute illness (OR 2.2 per point, p < 0.001), and Charlson score (OR 1.12 per point, p = 0.04) were associated with hospital mortality. K. pneumoniae was associated with increased hospital survival compared to other CRGNB (p = 0.03).. CRGNB infections are associated with previous antibiotic and health care exposure. Mortality is related to age and the severity of chronic and acute illness.

Topics: Age Factors; Aged; Aged, 80 and over; Anti-Bacterial Agents; beta-Lactam Resistance; Carbapenems; Cohort Studies; Drug Therapy, Combination; Female; Gram-Negative Bacteria; Gram-Negative Bacterial Infections; Humans; Male; Middle Aged; Polymyxin B; Prospective Studies; Renal Insufficiency; Rifampin; Survival Analysis; Treatment Outcome

The antimicrobial treatment of Stenotrophomonas maltophilia infections is complicated by intrinsic multidrug resistance and a lack of reliable susceptibility data. We assessed the activity of colistin (COL), rifampicin (RIF) and tigecycline (TGC) alone and in combination using a range of in vitro susceptibility testing methodologies and a simple invertebrate model of S. maltophilia infection (Galleria mellonella). Synergy [fractional inhibitory concentration indices (FICIs) ≤0.5] between COL and either RIF or TGC was observed against 92 % and 88 % of 25 S. maltophilia isolates, respectively, despite resistance to one or another of the single agents alone. In time-kill assays, COL combined with either RIF or TGC was superior to single agents, but only the COL/RIF regimen was reliably bactericidal. The in vitro findings correlated with treatment outcomes in G. mellonella, with heightened survival observed for larvae treated with COL/RIF or COL/TGC compared with COL, RIF or TGC alone. COL combined with RIF was the most effective combination overall in both in vitro and in vivo (p < 0.05) assays. Given the difficulty in selecting appropriate therapy for S. maltophilia infections, regimens consisting of COL combined with RIF or TGC could be considered for clinical use.

Topics: Animals; Colistin; Disease Models, Animal; Drug Resistance, Multiple, Bacterial; Drug Synergism; Drug Therapy, Combination; Gram-Negative Bacterial Infections; Lepidoptera; Microbial Viability; Minocycline; Rifampin; Stenotrophomonas maltophilia; Survival Analysis; Tigecycline; Treatment Outcome

Multidrug-resistant Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa have become common in many regions, often requiring therapy with colistin or polymyxin B. An increase in resistance to these agents would render many infections untreatable. We tested the activity of polymyxin B and the novel polymyxin analogue CB-182,804 against over 5,000 recent Gram-negative clinical isolates from New York City, a region with a high prevalence of multiresistant strains. Over 96% of Escherichia coli, K. pneumoniae, A. baumannii, and P. aeruginosa were susceptible to polymyxin B; only 76% of Enterobacter spp. was susceptible. The MICs of CB-182,804 were generally two-fold higher than polymyxin B and cross-resistance was observed. The addition of rifampin resulted in synergistic inhibition and bactericidal activity in time kill studies, and restored activity against all polymyxin-resistant strains. The synergistic effect of the combination with rifampin was most pronounced against A. baumannii strains, and was slightly greater with CB-182,804 than with polymyxin B against K. pneumoniae and Enterobacter spp. Despite considerable usage of polymyxin B and colistin in this region, polymyxin B retains excellent activity against most Gram-negative isolates. CB-182,804 shows similar activity, particularly when combined with rifampin. The clinical utility of CB-182,804 remains to be determined.

Topics: Anti-Bacterial Agents; Drug Resistance, Multiple, Bacterial; Drug Synergism; Gram-Negative Bacteria; Gram-Negative Bacterial Infections; Humans; Microbial Sensitivity Tests; New York City; Polymyxin B; Polymyxins; Rifampin

Paragonimiasis is a food-borne zoonosis caused by a trematode of the genus Paragonimus(1,2). Infestation is rare in Spain, but the influx of people from endemic areas should make us keep this condition in the differential diagnosis of our patients(2,5). We report the case a patient from Ecuador and resident in Spain for 7 years with active pulmonary tuberculosis on arrival in Spain and later diagnosed with of pulmonary paragonimiasis due to persistent haemoptysis. The diagnosis was established by surgical lung specimen showing granulomas containing parasite eggs and the macroscopic view of the fluke within a lung cavity. Initial tuberculosis treatment and current treatment with praziquantel controlled both conditions.

Topics: Adult; Animals; Anthelmintics; Antitubercular Agents; Caulobacteraceae; Delayed Diagnosis; Ecuador; Ethambutol; Food Parasitology; Gram-Negative Bacterial Infections; Granuloma; Hemoptysis; Humans; Isoniazid; Lung Diseases, Parasitic; Male; Paragonimiasis; Pneumonia, Bacterial; Praziquantel; Pyrazinamide; Radiography; Rifampin; Spain; Tuberculosis, Pulmonary

Three attenuated Aeromonas hydrophila vaccines were developed from the virulent 2009 West Alabama isolates through selection for resistance to both novobiocin and rifampicin. When channel catfish (Ictalurus punctatus) were IP injected with 4×105 colony-forming unit (CFU) of the mutants, no fish died. However, when the same age and size matched channel catfish were IP injected with similar amount of their virulent parents, 80-100% fish died. Similarly, when Nile tilapia (Oreochromis niloticus) were IP injected with 2×108 CFU of the mutants, no fish died. However, when Nile tilapia were IP injected with similar amount of the mutants, all fish died. Vaccination of channel catfish with the mutants at dose of 4×105 CFU/fish offered 86-100% protection against their virulent parents at 14 days post vaccination (dpv). Vaccination of Nile tilapia with the mutants at dose of 2×108 CFU/fish offered 100% protection against their virulent parents at 14, 28, and 56 dpv. Agglutination assay results suggested that protection elicited by the mutants was partially due to antibody-mediated immunity. Taken together, our results suggest that the three attenuated vaccines might be used to protect channel catfish and Nile tilapia against the highly virulent 2009 West Alabama isolates of A. hydrophila.

Topics: Aeromonas hydrophila; Alabama; Animals; Anti-Bacterial Agents; Antibodies, Bacterial; Bacterial Vaccines; Cichlids; Drug Resistance, Bacterial; Fish Diseases; Gram-Negative Bacterial Infections; Ictaluridae; Mutation; Novobiocin; Rifampin; Survival Analysis; Vaccines, Attenuated; Virulence

Mutation frequencies were studied in 174 Stenotrophomonas maltophilia isolates from clinical and nonclinical environments by detecting spontaneous rifampin-resistant mutants in otherwise-susceptible populations. The distribution of mutation frequencies followed a pattern similar to that found for other bacterial species, with a modal value of 1 x 10(-8). Nevertheless, the proportion of isolates showing mutation frequencies below the modal value (hypomutators) was significantly higher for S. maltophilia than those so far reported in other organisms. Low mutation frequencies were particularly frequent among environmental S. maltophilia strains (58.3%), whereas strong mutators were found only among isolates with a clinical origin. These results indicate that clinical environments might select bacterial populations with high mutation frequencies, likely by second-order selection processes. In several of the strong-mutator isolates, functional-complementation assays with a wild-type allele of the mutS gene demonstrated that the mutator phenotype was due to the impairment of MutS activity. In silico analysis of the amino acid changes present in the MutS proteins of these hypermutator strains in comparison with the normomutator isolates suggests that the cause of the defect in MutS might be a H683P amino acid change.

Topics: Anti-Bacterial Agents; Bacterial Proteins; Drug Resistance, Bacterial; Environmental Microbiology; Genetic Complementation Test; Gram-Negative Bacterial Infections; Mutation; MutS DNA Mismatch-Binding Protein; Polymorphism, Genetic; Rifampin; Stenotrophomonas maltophilia

Topics: Anti-Bacterial Agents; Bacteriuria; Biofilms; Catheter-Related Infections; Chloramphenicol; Disease Susceptibility; Drug Resistance, Multiple, Bacterial; Drug Therapy, Combination; Equipment Contamination; Gram-Negative Bacterial Infections; Humans; Primary Myelofibrosis; Rifampin; Stenotrophomonas maltophilia; Urinary Catheterization; Urinary Retention

Seventy-four strains representing the four species of the genus Dialister were isolated from various clinical samples. Dialister pneumosintes and Dialister micraerophilus were the two mainly encountered species. Fifty-five isolates were tested against 14 antimicrobial agents. Decreased susceptibilities to piperacillin, metronidazole, macrolides, fluoroquinolones, and rifampin were demonstrated. The clinical impact of these decreased susceptibilities remains to be investigated but should prompt microbiologists to perform antimicrobial susceptibility testing for clinically important Dialister spp.

Topics: Anti-Bacterial Agents; Drug Resistance, Bacterial; Gram-Negative Bacterial Infections; Humans; Microbial Sensitivity Tests; Species Specificity; Veillonellaceae

To investigate the aetiology of seed and boll rot of cotton grown in South Carolina (SC).. Bacteria were isolated from diseased locules of cotton bolls collected in a field in SC, USA and tested for the ability to cause comparable disease symptoms in greenhouse grown cotton fruit. Spontaneously generated rifampicin-resistant (Rif(r)) mutants of the isolates were used in confirmatory pathogenicity tests. Resistance to the antibiotic was both stable and effective in differentiating between an inoculated Rif(r) strain, rifampicin-sensitive contaminants and/or endophytes. A series of inoculation methods was tested at various boll developmental stages and at different fruiting nodes on the plant. Field disease symptoms were reproduced by inoculating bolls at 2 weeks postanthesis with bacterial suspensions ranging from 10(3) to 10(6) CFU ml(-1). Pathogenic isolates were categorized as Pantoea agglomerans on the basis of phenotype testing, fatty acid profiling (similarity index = 0.94), and 16s ribosomal DNA sequence analysis (99% nucleotide identity).. Pantoea agglomerans isolates from field-collected immature, diseased cotton caused comparable infection symptoms in greenhouse produced cotton fruit.. In 1999, significant yield losses in SC cotton resulted from a previously unobserved seed and boll rot that has since been reported in other southeastern states. This study demonstrated a role of P. agglomerans in producing opportunistic bacterial seed and boll rot of cotton.

Topics: Anti-Bacterial Agents; Base Sequence; DNA, Bacterial; DNA, Ribosomal; Drug Resistance, Bacterial; Fatty Acids; Gossypium; Gram-Negative Bacterial Infections; Pantoea; Phenotype; Plant Diseases; Rifampin; South Carolina

Topics: Animals; Anti-Bacterial Agents; Colistin; Drug Resistance, Multiple, Bacterial; Drug Synergism; Drug Therapy, Combination; Gram-Negative Bacterial Infections; Humans; Pseudomonas Infections; Rats; Rifampin; Sepsis; Treatment Failure

To determine the ability of the southern green stink bug (SGSB) (Nezara viridula L.) to transmit Pantoea agglomerans into cotton (Gossypium hirsutum) bolls.. An SGSB laboratory colony was kept on fresh green beans. A P. agglomerans variant resistant to rifampicin (Rif) (strain Sc 1-R) was used as the opportunistic cotton pathogen. Adult insects were individually provided green beans that were sterilized and then soaked in either sterile water or in a suspension of strain Sc 1-R. Insects were individually caged with an unopened greenhouse-grown cotton boll. After 2 days, live SGSB were collected, surfaced sterilized, ground, serially diluted, and then plated on nonselective media and media amended with Rif. Exterior and interior evidence of feeding on bolls was recorded 2 weeks after exposure to insects. Seed and lint tissue were harvested, ground, serially diluted, and then plated on media with and without Rif. Bacteria were recovered on nonselective media from all insects, and from seed and lint with signs of insect feeding at concentrations ranging from 10(2) to 10(9) CFU g(-1) tissue. The Sc 1-R strain was isolated only from insects exposed to the marked strain and from seed and lint of respective bolls showing signs of insect feeding. Evidence of insect feeding on the exterior wall of the carpel was not always apparent (47%), whereas feeding was always observed (100%) on the interior wall in association with bacterial infections of seed and lint.. Nezara viridula readily ingested the opportunistic P. agglomerans strain Sc 1-R and transmitted it into unopened cotton bolls. Infections by the transmitted Sc 1-R strain caused rotting of the entire locule that masked internal carpel wounds incurred by insect feeding. Bacteria were recovered from penetration points by insects not exposed to the pathogen, but locule damage was limited to the area surrounding the feeding site (c. 3 mm).. This is the first study that demonstrates the ability of SGSB to acquire and transmit plant pathogenic bacteria into cotton bolls.

Topics: Animals; Anti-Bacterial Agents; Colony Count, Microbial; Culture Media; Drug Resistance, Microbial; Gossypium; Gram-Negative Bacterial Infections; Heteroptera; Insect Vectors; Pantoea; Plant Diseases; Rifampin; RNA, Bacterial; RNA, Ribosomal, 16S; Seeds

Topics: Anti-Bacterial Agents; Cystic Fibrosis; Drug Therapy, Combination; Gentamicins; Gram-Negative Bacterial Infections; Humans; Lactoferrin; Microbial Sensitivity Tests; Recombinant Proteins; Rifampin; Stenotrophomonas maltophilia

A 5-month-old Morgan filly was presented to the Atlantic Veterinary College with a history of lethargy, fever, depression, anorexia, and dependent ventral edema. Diagnostic tests revealed severe inflammation, hypoproteinemia, and thickened small intestinal loops. Protein-losing enteropathy caused by Lawsonia intracellularis was diagnosed and treated successfully with erythromycin-rifampin.

Topics: Animals; Anti-Bacterial Agents; Antibiotics, Antitubercular; Diagnosis, Differential; Drug Therapy, Combination; Erythromycin; Female; Gram-Negative Bacterial Infections; Horse Diseases; Horses; Lawsonia Bacteria; Protein-Losing Enteropathies; Rifampin; Weaning

Stenotrophomonas maltophilia is characterized by intrinsic resistance to a variety of antimicrobials. Therapeutic options are often limited particularly after the emergence of isolates resistant to trimethoprim/sulfamethoxazole. The application of colistin for infections caused by multidrug-resistant Gram-negative pathogens is limited due to its toxicity. In order to evaluate the activity of the interaction of colistin with rifampin or trimethoprim/sulfamethoxazole on S. maltophilia, 24 different isolates resistant to trimethoprim/sulfamethoxazole were in vitro exposed over-time to the combination of 1x and 4 x MIC of colistin with 2 microg/ml of rifampin or 2/38 microg/ml of trimethoprim/sulfamethoxazole. The applied concentrations for rifampin and trimethoprim/sulfamethoxazole reflect their mean serum levels. Synergy of colistin and rifampin was documented after the first two hours of bacterial growth for approximately 60% of isolates and it occurred with both applied concentrations of colistin. The interaction of colistin and rifampin prevented regrowth observed when single colistin was applied. Synergy of colistin and trimethoprim/sulfamethoxazole was mainly found when colistin was applied at a concentration of 4 x MIC involving 41.7% of isolates after 24 h of growth. In the presence of trimethoprim/sulfamethoxazole bacterial regrowth, observed when single colistin was applied, was prevented. It is concluded that growth of multidrug-resistant S. maltophilia is significantly inhibited by the interaction of colistin and rifampin and to a lesser extent of colistin and trimethoprim/sulfamethoxazole. These results merit further study in both the animal model and the clinical setting.

Topics: Anti-Bacterial Agents; Colistin; Colony Count, Microbial; Cross Infection; Drug Resistance, Multiple, Bacterial; Drug Synergism; Gram-Negative Bacterial Infections; Humans; Microbial Sensitivity Tests; Rifampin; Stenotrophomonas maltophilia; Trimethoprim, Sulfamethoxazole Drug Combination

Proliferative enteropathy (PE) is a transmissible enteric disease caused by Lawsonia intracellularis. An outbreak of equine PE was diagnosed in foals from 3 breeding farms. Most foals had been weaned prior to the appearance of clinical signs, which included depression, rapid and marked weight loss, subcutaneous oedema, diarrhoea and colic. Poor body condition with a rough haircoat and a potbellied appearance were common findings in affected foals. Respiratory tract infection, dermatitis and intestinal parasitism were also found in some foals. Haematological and plasma biochemical abnormalities included hypoproteinaemia, transient leucocytosis, anaemia and increased serum creatinine kinase concentration. Postmortem diagnosis of PE was confirmed on 4 foals based on the presence of characteristic intracellular bacteria within the apical cytoplasm of proliferating crypt epithelial cells of the intestinal mucosa, using silver stains, and by results of PCR analysis and immunohistochemistry. Antemortem diagnosis of equine PE was based on the clinical signs, hypoproteinaemia and the exclusion of common enteric infections. Faecal PCR analysis was positive for the presence of L. intracellularis in 6 of 18 foals tested while the serum of all 7 foals with PE serologically evaluated had antibodies against L. intracellularis. Most foals were treated with erythromycin estolate alone or combined with rifampin for a minimum of 21 days. Additional symptomatic treatments were administered when indicated. All but one foal treated with erythromycin survived the infection. This study indicates that equine PE should be included in the differential diagnosis of outbreaks of rapid weight loss, diarrhoea, colic and hypoproteinaemia in weanling foals.

Topics: Animal Husbandry; Animals; Canada; Colic; Diarrhea; Disease Outbreaks; Drug Therapy, Combination; Enteritis; Erythromycin Estolate; Gram-Negative Bacterial Infections; Horse Diseases; Horses; Hypoproteinemia; Lawsonia Bacteria; Rifampin; Weight Loss

Topics: Community-Acquired Infections; Drug Therapy, Combination; Flavobacterium; Gram-Negative Bacterial Infections; Humans; Infant, Newborn; Male; Meningitis, Bacterial; Rifampin; Vancomycin

Topics: Dose-Response Relationship, Drug; Drug Evaluation; Drug Resistance, Microbial; Gram-Negative Bacteria; Gram-Negative Bacterial Infections; Gram-Positive Bacteria; Gram-Positive Bacterial Infections; Humans; Rifampin