cefoxitin and Disease-Models--Animal

When Zika virus emerged as a public health emergency there were no drugs or vaccines approved for its prevention or treatment. We used a high-throughput screen for Zika virus protease inhibitors to identify several inhibitors of Zika virus infection. We expressed the NS2B-NS3 Zika virus protease and conducted a biochemical screen for small-molecule inhibitors. A quantitative structure-activity relationship model was employed to virtually screen ∼138,000 compounds, which increased the identification of active compounds, while decreasing screening time and resources. Candidate inhibitors were validated in several viral infection assays. Small molecules with favorable clinical profiles, especially the five-lipoxygenase-activating protein inhibitor, MK-591, inhibited the Zika virus protease and infection in neural stem cells. Members of the tetracycline family of antibiotics were more potent inhibitors of Zika virus infection than the protease, suggesting they may have multiple mechanisms of action. The most potent tetracycline, methacycline, reduced the amount of Zika virus present in the brain and the severity of Zika virus-induced motor deficits in an immunocompetent mouse model. As Food and Drug Administration-approved drugs, the tetracyclines could be quickly translated to the clinic. The compounds identified through our screening paradigm have the potential to be used as prophylactics for patients traveling to endemic regions or for the treatment of the neurological complications of Zika virus infection.

Topics: Animals; Antiviral Agents; Artificial Intelligence; Chlorocebus aethiops; Disease Models, Animal; Drug Evaluation, Preclinical; High-Throughput Screening Assays; Immunocompetence; Inhibitory Concentration 50; Methacycline; Mice, Inbred C57BL; Protease Inhibitors; Quantitative Structure-Activity Relationship; Small Molecule Libraries; Vero Cells; Zika Virus; Zika Virus Infection

Hyperoxia therapy is often required to treat newborns with respiratory disorders. Prolonged hyperoxia exposure increases oxidative stress and arrests alveolar development in newborn rats. Tn antigen is N-acetylgalactosamine residue that is one of the most remarkable tumor-associated carbohydrate antigens. Tn immunization increases the serum anti-Tn antibody titers and attenuates hyperoxia-induced lung injury in adult mice. We hypothesized that maternal Tn immunizations would attenuate hyperoxia-induced lung injury through the suppression of oxidative stress in neonatal rats. Female Sprague-Dawley rats (6 weeks old) were intraperitoneally immunized five times with Tn (50 μg/dose) or carrier protein at biweekly intervals on 8, 6, 4, 2, and 0 weeks before the day of delivery. The pups were reared in room air (RA) or 2 weeks of 85% O

Topics: Animals; Animals, Newborn; Antibodies; Antigens, Tumor-Associated, Carbohydrate; Biomarkers; Cytokines; Disease Models, Animal; Female; Hyperoxia; Immunization; Immunohistochemistry; Inflammation; Lung Injury; Macrophages, Alveolar; Maternal Exposure; Oxidative Stress; Rats

Tumor-associated carbohydrate antigens (TACAs) are attractive targets for anticancer vaccine development. Due to the low immunogenicity of TACAs, a powerful carrier system is needed to boost immune responses. Virus-like particles (VLPs) are an exciting platform for delivering TACAs to the immune system. The high symmetry of VLPs enables the display of TACAs in an organized manner, which in turn can potently activate antibody secreting B cells, eliciting high titers of antiglycan IgG antibodies. In this chapter, the protocol for conjugating a prototypical TACA, the Tn antigen to a VLP, bacteriophage Qβ, is presented. On an average around 370 copies of Tn can be attached to each Qβ capsid. Immunization of mice with Qβ-Tn conjugate leads to over two orders of magnitude higher IgG antibodies compared to control mice receiving Qβ only without the Tn antigen. Antibodies induced by Qβ-Tn recognize Tn-expressing tumor cells strongly and protect mice from tumor-induced death. The techniques for evaluating antibody titers by enzyme-linked immunosorbent assay, antibody binding to tumor cells by flow cytometry, and the protection efficacy of the vaccine in a therapeutic model of tumor are discussed in this chapter.

Topics: Allolevivirus; Animals; Antigens, Tumor-Associated, Carbohydrate; B-Lymphocytes; Biomarkers, Tumor; Disease Models, Animal; Flow Cytometry; Humans; Immunization; Mice; Neoplasms; Vaccines, Conjugate; Vaccines, Virus-Like Particle

Changes in glycosylation of the cancer cell glycocalyx are a hallmark of metastasizing cancers and critically contribute to distant metastasis. In this chapter we concentrate on two lectins capable of specifically binding tumor-associated glycans in cryostat or formalin-fixed, paraffin-embedded tissue sections derived from primary clinical material, genetically engineered mouse models with endogenous cancer formation or xenograft mouse models. The snail lectin of Helix pomatia (HPA) binds N-acetylgalactosamine (GalNAc) that is expressed among others as Tn antigen (O-linked GalNAc) in primary tumors and metastases in several human adenocarcinomas. Another lectin, Phaseolus vulgaris leucoagglutinin (PHA-L) binds to complex β1-6 branched N-linked oligosaccharides associated with increased metastatic potential in breast, colon, and prostate cancer. Using these two lectins both O- and N-linked alterations in the glycocalyx of cancer cells can be monitored. As they are commercially available in a biotinylated or fluorescence-labeled form they can be readily used in cancer metastasis studies.

Topics: Animals; Antigens, Tumor-Associated, Carbohydrate; Biomarkers; Cell Line, Tumor; Disease Models, Animal; Glycosylation; Heterografts; Histocytochemistry; Humans; Lectins; Mice; Microscopy; Neoplasm Metastasis; Neoplasms; Protein Binding

Topics: Animal Structures; Animals; Bacterial Load; beta-Lactam Resistance; beta-Lactamases; Cefepime; Cefoxitin; Cephalosporins; Disease Models, Animal; Drug Interactions; Drug Therapy, Combination; Enterobacteriaceae; Enterobacteriaceae Infections; Humans; Mice; Microbial Sensitivity Tests; Survival Analysis; Treatment Outcome

We investigated the efficiency of the cephamycin cefoxitin as an alternative to carbapenems for the treatment of urinary tract infections (UTIs) due to Escherichia coli producing CTX-M-type extended-spectrum β-lactamases. The susceptible, UTI-inducing E. coli CFT073-RR strain and its transconjugant CFT073-RR Tc (pbla(CTX-M-15)), harboring a bla(CTX-M-15) carrying-plasmid, were used for all experiments. MICs of cefoxitin (FOX), ceftriaxone (CRO), imipenem (IMP), and ertapenem (ETP) for CFT073-RR and CFT073-RR Tc (pbla(CTX-M-15)) were 4 and 4, 0.125 and 512, 0.5 and 0.5, and 0.016 and 0.032 μg/ml, respectively. Bactericidal activity was similarly achieved in vitro against the two strains after 3 h of exposure to concentrations of FOX, IMI, and ETP that were 2 times the MIC, whereas CRO was not bactericidal against CFT073-RR Tc (pbla(CTX-M-15)). The frequencies of spontaneous mutants of the 2 strains were not higher for FOX than for IMP or ETP. In the murine model of UTIs, mice infected for 5 days were treated over 24 h. Therapeutic regimens in mice (200 mg/kg of body weight every 3 h or 4 h for FOX, 70 mg/kg every 6 h for CRO, 100 mg/kg every 2 h for IMP, and 100 mg/kg every 4 h for ETP) were chosen in order to reproduce the percentage of time that free-drug concentrations above the MIC are obtained in humans with standard regimens. All antibiotic regimens produced a significant reduction in bacterial counts (greater than 2 log(10) CFU) in kidneys and bladders for both strains (P < 0.001) without selecting resistant mutants in vivo, but the reduction obtained with CRO against CFT073-RR Tc (pbla(CTX-M-15)) in kidneys was significantly lower than that obtained with FOX. In conclusion, FOX appears to be an effective therapeutic alternative to carbapenems for the treatment of UTIs due to CTX-M-producing E. coli.

Topics: Animals; Anti-Bacterial Agents; Bacterial Load; beta-Lactamases; beta-Lactams; Carbapenems; Cefoxitin; Ceftriaxone; Conjugation, Genetic; Disease Models, Animal; Drug Administration Schedule; Ertapenem; Escherichia coli; Escherichia coli Infections; Female; Humans; Imipenem; Kidney; Mice; Microbial Sensitivity Tests; Mutation Rate; Plasmids; Urinary Bladder; Urinary Tract Infections

Mucin-type O-linked oligosaccharides (O-glycans) are primary components of the intestinal mucins that form the mucus gel layer overlying the gut epithelium. Impaired expression of intestinal O-glycans has been observed in patients with ulcerative colitis (UC), but its role in the etiology of this disease is unknown. Here, we report that mice with intestinal epithelial cell-specific deficiency of core 1-derived O-glycans, the predominant form of O-glycans, developed spontaneous colitis that resembled human UC, including massive myeloid infiltrates and crypt abscesses. The colitis manifested in these mice was also characterized by TNF-producing myeloid infiltrates in colon mucosa in the absence of lymphocytes, supporting an essential role for myeloid cells in colitis initiation. Furthermore, induced deletion of intestinal core 1-derived O-glycans caused spontaneous colitis in adult mice. These data indicate a causal role for the loss of core 1-derived O-glycans in colitis. Finally, we detected a biosynthetic intermediate typically exposed in the absence of core 1 O-glycan, Tn antigen, in the colon epithelium of a subset of UC patients. Somatic mutations in the X-linked gene that encodes core 1 β1,3-galactosyltransferase-specific chaperone 1 (C1GALT1C1, also known as Cosmc), which is essential for core 1 O-glycosylation, were found in Tn-positive epithelia. These data suggest what we believe to be a new molecular mechanism for the pathogenesis of UC.

Topics: Animals; Antigens, Tumor-Associated, Carbohydrate; Base Sequence; Colitis; Colon; Disease Models, Animal; DNA Primers; Galactosyltransferases; Humans; Intestinal Mucosa; Mice; Mice, 129 Strain; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic; Molecular Chaperones; Mutation; Polysaccharides

Continuous and twice-daily cefoxitin dosing was used in a highly lethal model of acute peritonitis in mice using intraperitoneal (IP) Klebsiella pneumoniae (Kpn). The purpose was to use antibiotics to create a model of chronic infection. Male Balb/c mice (averaging 20 g body weight) were inoculated IP with 10(3) colony-forming units (CFU) Kpn serotype 2. Controls received subcutaneous saline either twice daily or continuously. Antibiotic groups received 300 mg/kg per day of cefoxitin either twice daily or continuously. Survival and daily weight losses were determined. Another group was inoculated with 10(3) Kpn given twice daily saline or cefoxitin and harvested at 24 hours. Leukocyte counts were performed on peritoneal exudate cells (PEC) and peripheral blood. Cultures determined Kpn counts in blood, lung, and PEC. By 24 hours, saline-treated animals had lost more weight than cefoxitin mice (1 g vs. 2 g, P < 0.05). Continuous cefoxitin showed significant advantage with 50 per cent mortality at 5 days. Kpn levels were not significantly altered by cefoxitin. Cefoxitin treatment extended chronicity by preventing weight loss and increasing survival in a highly lethal, monomicrobial peritonitis model. This model will allow future study of specific host defense mechanisms over a prolonged time period.

Topics: Animals; Anti-Bacterial Agents; Ascitic Fluid; Bacteremia; Cefoxitin; Chronic Disease; Colony Count, Microbial; Disease Models, Animal; Injections, Subcutaneous; Klebsiella Infections; Klebsiella pneumoniae; Leukocyte Count; Lung; Male; Mice; Mice, Inbred BALB C; Neutrophils; Peritonitis; Random Allocation; Serotyping; Survival Rate; Weight Loss

To compare the potential therapeutic effect of liposomal vs. free cefoxitin.. Randomized, controlled study, using a rat model of peritonitis.. Government research facility.. Male Sprague-Dawley rats.. Rats were infused intraperitoneally with 6.5 x 10(8) colony forming units of Escherichia coli over 12 hrs. Animals were then randomized to receive intravenous saline, free cefoxitin, liposomal cefoxitin, or plain liposomes twice daily until they were killed.. Free cefoxitin significantly reduced the number of E. coli after 24 hrs compared with saline treatment in both liver and spleen. However, liposomal cefoxitin further decreased the bacterial content by five-fold to ten-fold in these organs. Minimal bactericidal effect was observed in animals injected with plain liposomes. Although administration of liposomal cefoxitin for 7 days further reduced bacterial counts in liver and spleen, there was no apparent beneficial bactericidal effect of free cefoxitin over saline at 7 days. There was approximately a ten-fold reduction in bacterial content in the lungs after 24 hrs in all three treatments, but no further reduction was observed after 7 days. There was no difference in 7-day survival rate in animals treated with plain liposomes or saline (45% vs. 39%). Although survival tended to increase with free cefoxitin treatment (64%), this outcome was significantly improved with the use of liposomal cefoxitin (82%).. Liposomal cefoxitin enhanced bacterial killing in liver and spleen in this model of E. coli peritonitis. It also improved survival outcome relative to no treatment but not compared with free cefoxitin.

Topics: Animals; Body Weight; Cefoxitin; Cephamycins; Disease Models, Animal; Drug Carriers; Escherichia coli Infections; Infusions, Intravenous; Liposomes; Male; Peritonitis; Random Allocation; Rats; Rats, Sprague-Dawley

The plasma and peritoneal fluid pharmacokinetic parameters obtained after the intravenous administration of free and liposomal cefoxitin were studied in a porcine model of intraabdominal sepsis. No prior assumptions were made to predict the number of compartments pertaining to drug clearance from the administration of either cefoxitin formulation. The experimental data obtained were applied to fit mathematical models of multiexponential drug clearance and the pharmacokinetic data were found to best fit a two-compartment open model. Liposomal encapsulation significantly altered the plasma drug distribution pattern resulting in changes in the magnitude of a number of pharmacokinetic parameters examined. The mean post-distributive half-life of liposomal cefoxitin was substantially longer than that of free cefoxitin by at least 3 times. The peritoneal cavity appeared to provide a reservoir for the initial distributive phase of rapid drug clearance from the plasma compartment followed by a less-rapid post-distributive phase. The cumulative drug level, as determined by the area under the concentration curve (AUC) as a function of time, in the plasma of animals treated with liposomal cefoxitin was about 3-4 fold as high as that of animals treated with free cefoxitin. The differences in pharmacokinetic parameters appeared to account for the improved therapeutic efficacy of liposomal cefoxitin in this animal model.

Topics: Abdomen; Animals; Area Under Curve; Ascitic Fluid; Cefoxitin; Cephamycins; Disease Models, Animal; Drug Carriers; Half-Life; Injections, Intravenous; Liposomes; Male; Sepsis; Swine

The bactericidal effect of free versus liposomal cefoxitin was evaluated in the major reticuloendothelial organs in a porcine model of intra-abdominal sepsis. Yorkshire Landrace pigs were inoculated with 3.2 x 10(10) (n = 5) or 1.4 x 10(11) (n = 7) cfu of Escherichia coli mixed in sterile feces/animal. Two treatment groups inoculated with 1.4 x 10(11) cfu were established: free cefoxitin (n = 9) and liposomal cefoxitin (n = 9). All animals were maintained under anesthesia and euthanized after 24 h. The number of E. coli recovered in the liver, lungs, and spleen was significantly affected by inoculum size (p < .05). The liver had significantly higher numbers of bacteria (p < .05) compared with the other organs, regardless of the inoculum size. The liver and the lung of the liposomal cefoxitin-treated group showed significantly lower numbers of E. coli (5.0 x 10(4) and 6.3 x 10(2), respectively) compared with the untreated (liver, 6.3 x 10(7); lung, 2.0 x 10(6)) and free cefoxitin (liver, 5.0 x 10(6); lung, 7.9 x 10(4))-treated groups (p < .05). At 2 h following the injection of free and liposomal cefoxitin, the decrease of E. coli in peritoneal fluid compared with the nontreated septic group was significant (p < .05). No growth was observed from blood cultures taken 24 h after sepsis induction. All control experiments yielded negative cultures. The results of these experiments demonstrated that liposomal cefoxitin exerts an enhanced bactericidal effect in liver and lungs during Gram-negative sepsis.

Topics: Analysis of Variance; Animals; Cefoxitin; Cephamycins; Disease Models, Animal; Escherichia coli; Liposomes; Male; Sepsis; Swine

Cefoxitin, cefotetan, and cefmetazole were compared in 10-day therapy of intra-abdominal and subcutaneous infections caused by three organisms: Bacteroides fragilis and Bacteroides thetaiotaomicron combined with either Escherichia coli or Staphylococcus aureus. Intra-abdominal infection was caused by B. fragilis plus B. thetaiotaomicron plus E. coli. Therapy was initiated immediately before inoculation or was delayed for 8 h. Mortality was 14 of 30 (47%) for saline-treated mice, and all survivors developed abscesses. Immediate therapy reduced mortality and the percentage of mice with abscesses (in survivors), respectively, to 17 and 20% with cefoxitin, 0 and 13% with cefotetan, and 0 and 17% with cefmetazole, and the numbers of all bacteria were reduced by all the cephalosporins. Delayed therapy reduced mortality and abscess formation, respectively, to 20 and 8% of mice with cefoxitin, 10 and 93% with cefotetan, and 7 and 96% with cefmetazole. B. thetaiotaomicron survived in all abscesses treated with cefotetan and cefmetazole. Subcutaneous abscesses were caused by each organism alone or in combinations of one aerobe (S. aureus or E. coli) and one or two Bacteroides species. Early therapy reduced the numbers of all bacteria independent of their in vitro susceptibility. All agents reduced the number of each Bacteroides species with either E. coli or S. aureus. However, when therapy was delayed, cefotetan and cefmetazole were less effective than cefoxitin against B. thetaiotaomicron. Cefotetan was the most active agent against E. coli, and cefmetazole was the most effective against S. aureus. These data illustrate the efficacy of all tested cephalosporins in the prophylaxis of polymicrobial infections.

Topics: Abdomen; Abscess; Animals; Bacterial Infections; Bacteroides fragilis; Bacteroides Infections; Cefmetazole; Cefotetan; Cefoxitin; Disease Models, Animal; Escherichia coli; Escherichia coli Infections; Male; Mice; Microbial Sensitivity Tests; Skin Diseases, Bacterial; Staphylococcal Infections; Staphylococcal Skin Infections; Staphylococcus aureus

The systemic tumor necrosis factor (TNF) response has been extensively studied during infection. In addition, antibiotics that cause cell-wall lysis have been associated with endotoxinemia and, therefore, could trigger TNF release. We studied the effects of pretreatment with cefoxitin and/or anti-TNF antibody on mortality and early (90 minutes) and delayed (6 hours) serum TNF levels in a murine model of mixed Escherichia coli/Bacteroides fragilis peritonitis. At low and intermediate inocula levels, cefoxitin, but not anti-TNF antibody, prevented death, and low serum TNF levels were noted in all groups. At the highest inoculum level, mortality was uniform in control, cefoxitin, and anti-TNF antibody groups, and a significant elevation in serum TNF levels was seen only at the 6-hour point in animals receiving cefoxitin. The addition of anti-TNF antibody to cefoxitin at this inoculum level abrogated the 6-hour rise in serum TNF levels and reduced mortality to 40%. These results emphasize that the cytokine response in disease is dependent on both the nature of the insult and other forms of therapeutic interventions.

Topics: Animals; Antibodies, Anti-Idiotypic; Bacteroides fragilis; Bacteroides Infections; Cefoxitin; Disease Models, Animal; Drug Evaluation, Preclinical; Drug Therapy, Combination; Escherichia coli Infections; Immunoglobulin G; Injections, Intramuscular; Injections, Intraperitoneal; Male; Mice; Mice, Inbred BALB C; Peritonitis; Survival Rate; Tumor Necrosis Factor-alpha

Cefamandole, cefoxitin, cefotetan, ceftizoxime, imipenem plus cilastatin, and ampicillin plus sulbactam were compared in the eradication of subcutaneous abscess in mice caused by Bacteroides fragilis group organisms and Escherichia coli alone or in combination. The abscesses were examined 5 d after inoculation. B. fragilis group reached log10.1-11.0 organisms per abscess and E. coli log11.6-12.5. Imipenem plus cilastatin significantly reduced (in 6.9-10.6 logs) the number of E. coli and all members of B. fragilis group alone or in all combinations. Ampicillin plus sulbactam reduced the numbers of all B. fragilis group (in 4.2-7.2 logs) but was less effective against E. coli (reduction of 1.8-4.2 logs). Cefoxitin was effective in significantly reducing (in 4.9-6.2 logs) the number of E. coli and all members of B. fragilis group alone or in all combinations. Cefotetan was effective against B. fragilis (reduction of 5.1-6.6 logs) and E. coli alone or in combination but did not reduce the number of Bacteroides thetaiotaomicron, Bacteroides vulgatus, and Bacteroides ovatus. Ceftizoxime was effective against only B. ovatus (reduction of 3.7-5.8) and E. coli (reduction of 6.0-8.1 logs); it did not reduce the number of other organisms. Cefamandole was effective against only E. coli and was not effective against any member of the B. fragilis group. These in vivo data confirm the in vitro activity of these antimicrobials.

Topics: Abscess; Ampicillin; Animals; Anti-Bacterial Agents; Bacteroides fragilis; Bacteroides Infections; Cefamandole; Cefotetan; Cefoxitin; Ceftizoxime; Cilastatin; Cilastatin, Imipenem Drug Combination; Disease Models, Animal; Drug Combinations; Drug Therapy, Combination; Escherichia coli; Escherichia coli Infections; Imipenem; Male; Mice; Skin Diseases; Sulbactam

The relationships between capsulate and non-capsulate Bacteroides fragilis strains and Escherichia coli, and between capsulate and non-capsulate strains of the B. melaninogenicus group and Streptococcus pyogenes, were studied in a subcutaneous abscess model in mice. Selective antimicrobial agents directed against either aerobic or anaerobic bacteria were used alone or in combination to explore the effect of eradication of one component of the mixed infection. Single agent therapy effective against both aerobic and anaerobic flora was also employed. Single therapy of mixed infection directed at the elimination of only one organism (S. pyogenes, E. coli or Bacteroides sp.) caused significant reductions in the numbers of sensitive organisms and also smaller yet significant decreases in the numbers of insensitive organisms. However, the abscesses were not eliminated after such therapy. Combination therapy or use of a single agent (cefoxitin) directed against the aerobic and anaerobic components of the infection was more effective. Non-capsulate Bacteroides spp. became capsulate after passage in mice mixed with either S. pyogenes or E. coli. Therapy directed at the elimination of S. pyogenes and E. coli did not prevent the emergence of capsulate Bacteroides spp. These data demonstrate the synergy between all members of the B. fragilis group and E. coli and between the B. melaninogenicus group and S. pyogenes, and reiterate the need to direct antimicrobial therapy at the eradication of the aerobic and anaerobic components of mixed infections.

Topics: Abscess; Aerobiosis; Anaerobiosis; Animals; Bacteroides; Bacteroides fragilis; Bacteroides Infections; Cefoxitin; Disease Models, Animal; Drug Resistance, Microbial; Drug Therapy, Combination; Escherichia coli; Escherichia coli Infections; Gentamicins; Leucomycins; Male; Metronidazole; Mice; Microbial Sensitivity Tests; Prevotella melaninogenica; Skin Diseases; Streptococcal Infections; Streptococcus pyogenes

We present preliminary data on the role of antibiotics in intraabdominal sepsis using a new, clinically relevant animal model. Peritoneal cavity infection was induced by ligation and perforation of the cecum in adult rats. Surviving rats were randomized to receive either saline or cefoxitin at the time of cecal excision and peritoneal lavage, 18 h after the onset of infection. This is different from previous models of abdominal sepsis (in which antibiotics are given within 4 h of peritoneal contamination) and mimics the clinical setting in which antibiotics are initiated much later, at the time of operation. Antibiotic-treated rats received 20 mg cefoxitin i.m. every 8 h for 7 days; controls received saline at similar times. Thirty-nine of 67 control rats died (58%) versus 20 of 64 (31%) that received cefoxitin (p less than 0.005). We conclude that even with delayed administration, antibiotics appear to improve the outcome of intraabdominal sepsis. With further characterization of this model we plan to use it as an in vivo assay to compare the efficacy of different antimicrobial agents in intraabdominal sepsis.

Topics: Animals; Bacterial Infections; Cefoxitin; Disease Models, Animal; Male; Peritonitis; Random Allocation; Rats; Rats, Inbred Strains

We have noted that prairie dogs given cefoxitin develop diarrhea and lose weight yet survive for periods of up to 4 weeks. Therefore, we tested the hypothesis that cefoxitin causes Clostridium difficile cecitis in prairie dogs. Six prairie dogs were given a single intramuscular dose of 100 mg of cefoxitin per kg of body weight, and six control animals received saline; both groups were sacrificed 1 week later. Controls had no diarrhea and lost 2% of their body weight, whereas cefoxitin-treated animals had diarrhea (P less than 0.001) and lost 16% of their body weight (P less than 0.001); one animals died 6 days after cefoxitin challenge. None of the controls yielded C. difficile or had cecal cytotoxin or pseudomembranes detected. Cecal contents from all cefoxitin-treated animals, however, yielded C. difficile (P less than 0.01) and had cecal cytotoxin present (P less than 0.01). Four of five surviving animals also had cecal pseudomembranes present (P less than 0.01). These results demonstrate that in prairie dogs cefoxitin induces C. difficile cecitis. We conclude that the prairie dog is another model for the study of antibiotic-induced diarrhea. The disease in prairie dogs may have a more chronic course than in other animal models of C. difficile-induced diarrhea and may be useful as a model for studying certain aspects of C. difficile-induced diarrhea.

Topics: Animals; Bacterial Toxins; Cecal Diseases; Cecum; Cefoxitin; Clostridium; Diarrhea; Disease Models, Animal; Inflammation; Sciuridae

An attempt has been made to develop a chronic inflammatory arachnoiditis model in the rat to study the influence of subarachnoid or epidural steroids. Through chronically implanted catheters in Wistar rats (250-350 g), either triamcinolone (3.5-350 micrograms) or methylprednisolone (3.5-350 micrograms) was injected intrathecally, daily for 7 days or weekly for 7 weeks. Some rats also received 100 mg kg-1 cefoxitin and 0.5 mg deoxycortone by intramuscular injection. Equivalent control groups were included. High doses of intrathecal steroids caused marked weight loss and infection and many rats died. These effects were mitigated at a lower dosage especially by the addition of cefoxitin and deoxycortone. The effects of triamcinolone were more marked than those of methylprednisolone. No systematic histological evidence of neurotoxicity was observed after either steroid. Injections of talc failed to cause arachnoiditis or meningitis probably because sufficient particulate talc could not be injected through the narrow catheter.

Topics: Animals; Arachnoiditis; Cefoxitin; Desoxycorticosterone; Disease Models, Animal; Drug Interactions; Injections, Spinal; Male; Meningitis; Meningitis, Aseptic; Methylprednisolone; Methylprednisolone Hemisuccinate; Rats; Rats, Inbred Strains; Spinal Cord Diseases; Triamcinolone Acetonide

In the E. coli pyelonephritis, induced in female Wistar rats by retrograde infection (high pressure reflux), we investigated the influence of 1) the time of commencement of therapy, 2) the renal bacterial counts, i.e. the inflammatory activity of the pyelonephritis after endovesical instillation of cultures with different bacterial concentrations, and 3) the level of infection resistance of the experimental animal strain on the therapeutic response of the model infection with single doses of cefoxitin (150 mg/ml) and cefotaxime (5 mg/ml). Early commencement of therapy post inoculation was therapeutically advantageous provided the intrarenal multiplication of the infective organisms was not delayed or the initial bacterial concentrations were not too high. The mild form of pyelonephritis with lower renal bacterial concentrations and poor inflammatory activity after endovesical instillation of a low inoculum (10(4) cfu/ml) was less amenable to treatment than the inflammatory active pyelonephritis with high renal bacterial counts, using a high inoculum (10(7) cfu/ml). High renal bacterial counts after retrograde inoculation of an E. coli culture of 10(8) cfu/ml resulted in significant reduction of bacterial counts 48, 72 and 96 h post infectionem, with i.m. application of cefoxitin 12 h prior. For Wistar rat strain Bor:WIST, which showed a stronger infection resistance with lower renal bacterial concentrations and a stronger tendency to spontaneous healing, application of a single dose of cefotaxime (5 mg/ml) was therapeutically ineffective, whereas, in contrast, with Han: WIST rats the acute phase of E. coli pyelonephritis could be treated effectively.

Topics: Animals; Cefotaxime; Cefoxitin; Disease Models, Animal; Escherichia coli; Escherichia coli Infections; Female; Kidney; Pyelonephritis; Rats; Rats, Inbred Strains

The efficacy of beta-lactam antibiotics and amikacin alone and in various combinations against Pseudomonas aeruginosa was studied in a rabbit model simulating a closed-space infection in a locally neutropenic site. Six strains of P. aeruginosa were studied in semipermeable chambers placed subcutaneously in rabbits. Therapy was begun 4 h after inoculation of 5 X 10(4) CFU of bacteria per ml of pooled rabbit serum into the chambers. Antibiotics were administered intramuscularly every 6 h for 16 doses. Quantitative bacteriology was measured at the start of therapy and at 20, 44, and 92 h thereafter. Antibiotic concentrations were measured in blood and chamber fluid. Results were compared with in vitro tests of susceptibility and synergy. No single-agent therapy eradicated any of the six test organisms. Azlocillin (100 mg/kg per dose) plus amikacin (20 mg/kg per dose) eliminated five of six organisms by 92 h, and ceftizoxime (100 mg/kg per dose) plus amikacin (20 mg/kg per dose) eliminated three of six test strains. Azlocillin plus ceftizoxime (each 100 mg/kg per dose) failed to eliminate any of the six strains. To eliminate P. aeruginosa in this model, two drugs were required, with one being an aminoglycoside. In vitro susceptibility tests of synergy were predictive of successful therapy whenever the antibiotic concentrations (free and total) at the infection site exceeded the MBC for both the aminoglycoside alone and the beta-lactam when tested in combination with amikacin.

Topics: Agranulocytosis; Amikacin; Animals; Anti-Bacterial Agents; Azlocillin; Cefotaxime; Cefoxitin; Ceftizoxime; Disease Models, Animal; Drug Combinations; Female; Hydrogen-Ion Concentration; Kanamycin; Microbial Sensitivity Tests; Neutropenia; Penicillins; Protein Binding; Pseudomonas Infections; Rabbits