Comparison of In Vitro Bacterial Susceptibility to Common and Novel Equine Wound Care Dressings.

Antimicrobial resistance is becoming a problem of concern in the veterinary field, necessitating the use of effective topical treatments to aid the healing of wounds. Honey has been used for thousands of years for its medicinal properties, but in recent years medical-grade Manuka honey has been used to treat infected wounds. The goal of this study was to determine the relative susceptibility of four common equine wound pathogens to ten different types of antimicrobial agents based on the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The pathogens studied include ATCC lab-acclimated Pseudomonas aeruginosa, Escherichia coli, and methicillin-resistant Staphylococcus aureus and one from an equine sample submitted to the Colorado State Veterinary Diagnostic Laboratory (Streptococcus equi ssp. zooepidemicus (Streptococcus zooepidemicus)). An additional goal of the study was to describe the comparison of bactericidal activity of medical-grade Manuka honey, local honey, and commercial, food-grade honey to other commonly used wound dressings (20% hypertonic saline, silver sulfadiazine cream, PHMB gauze, and PHMB foam). The objective is to provide veterinary practitioners with comparative data on the use of a variety of antimicrobial dressings for inhibiting the growth of common wound bacteria. MIC and MBC for Manuka, store, and local honeys were comparable to those of sterile gauze, sugar, and hypertonic saline. Across bacterial species, local honey proved to have more bactericidal activity when compared to Manuka honey and commercial, food-grade honey. The MIC and MBC for PHMB gauze and foam was consistently at a higher dilution compared to the other antimicrobials. The majority of antimicrobials exhibited stronger inhibitory and bactericidal activity against a Streptococcus zooepidemicus isolate obtained from a wound compared to other bacteria that were ATCC lab-acclimated. Additional research for in vivo applications needs to be done to see whether differences exist in effective wound management.

Antimicrobial resistance and genetic diversity of Staphylococcus aureus collected from livestock, poultry and humans.

Staphylococcus aureus is one of the most prominent nosocomial, community and farm acquired bacterial infections among animals and human populations. The main purpose of our study was to identify and characterize antimicrobial resistance (AMR) among Staphylococcus aureus isolated from livestock, poultry and humans and to further identify the associated genes. Staphylococcus aureus isolates from human, bovine, swine and poultry were collected from different laboratories across the United States collected between 2003 and 2016. Antimicrobial susceptibility testing for 13 antimicrobials was performed and conventional PCR was used to detect the presence of the nuc gene, mec gene, and to detect int1 gene. Associations between the presence of mec and intl and specific AMR profiles were determined. Antimicrobial resistance was detected in all four host categories, with the highest overall rates found in swine, 100% resistant to tetracycline, 88% to penicillin and 64% clindamycin. The next highest was found among humans with 81.6% of isolates resistant to penicillin followed by 44% to clindamycin and 43% to erythromycin. Among beef cattle isolates, 63.2% were resistant to penicillin, 15.8% resistant to clindamycin and 15.8% to erythromycin. No isolates from any of the hosts were resistant to linezolid. Among poultry isolates, the highest AMR was found to clindamycin, followed by erythromycin and penicillin. Among dairy cattle, highest resistance was found to penicillin, followed by chloramphenicol and gentamicin. Dairy cattle were the only host category with isolates that are resistant to trimethoprim-sulfamethoxazole. Of the 220 isolates detected by latex agglutination, 217 were confirmed to be S. aureus via PCR of the nuc gene, 21.4% were positive for the mecA gene. Swine had the highest prevalence of the mecA gene, followed by humans, poultry and beef cattle. This study has demonstrated a high occurrence of penicillin resistance among all S. aureus isolates. There were differences observed between host species with tetracycline resistance being the highest among swine isolates and clindamycin being highest in poultry isolates. No detection of oxacillin resistance was found in isolates from dairy cattle but was found in isolates from all of the other host species, 94% of which contained the mecA gene.

Detection of anti-HEV antibodies and RNA of HEV in pigs from a hyperendemic Italian region with high human seroprevalence.

BACKGROUND: Pigs are considered the main reservoir of genotypes 3 and 4 of hepatitis E virus (HEV), which is the major cause of acute hepatitis of viral origin in humans worldwide. An increasing number of autochthonous HEV infections have been observed in recent years in industrialized countries, most likely as a result of zoonotic transmission through the consumption of raw or undercooked meat products. METHODS: Two hundred and thirty-three blood and liver samples were collected at four different local slaughterhouses from domestic pigs bred in Abruzzo, a region of south-central Italy, where there is the highest human seroprevalence to HEV compared with the rest of Italy. An indirect enzyme-linked immunosorbent assay kit was used for detecting anti-HEV IgG in the sera, while the presence of HEV RNA was investigated by performing a real-time reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS: Between 87.3% and 100% of swine serum samples collected in different slaughterhouses of Abruzzo were positive for anti-HEV antibodies. Conversely, none of the liver samples collected from the same animals were positive for HEV by real-time RT-PCR. CONCLUSIONS: The hypothesis of foodborne zoonotic transmission from local pigs as responsible for the hyperendemic status of Abruzzo cannot be corroborated. However, the high seroprevalence observed in pigs indicates that HEV is highly circulating in these territories. We propose to further investigate the role of wild fauna and trade in carrier pigs, and the maintenance of HEV virulence in the environment and meat supply chain to shed light on the possible sources of human infection and the degree of occupational risk.

Antimicrobial susceptibility survey on bacterial agents of canine and feline urinary tract infections: Weight of the empirical treatment.

OBJECTIVES: This work characterised the antimicrobial susceptibility of uropathogens isolated from empirically treated dogs and cats. Within-household transmission of uropathogens can involve humans and companion animals. Knowledge on the prevalence and susceptibility pattern of isolates from canine and feline urine samples and the impact of prior antimicrobial treatment is important to prevent the dissemination of antimicrobial resistance. METHODS: A retrospective study was conducted selecting antibiotic-treated companion animals. Urine samples were collected by cystocentesis and were submitted to an Italian diagnostic laboratory over a 2-year period (2013-2015). The antimicrobial susceptibility of the isolates was analysed both using Clinical and Laboratory Standards Institute (CLSI) guidelines and a formula to help select rational antimicrobial therapy. RESULTS: Gram-negative bacteria were clearly prevalent. Gentamicin had the highest impact factors. Amoxicillin/clavulanic acid and doxycycline appeared to be the most effective compounds against Gram-positive infections, whilst marbofloxacin may be a useful option against Gram-negative urinary tract infections (UTIs) as well as doxycycline and trimethoprim/sulfamethoxazole in cats and dogs, respectively. Consulting published studies, a comparable overall trend regarding bacterial species incriminated in canine and feline UTIs and their susceptibilities seems likely, despite different circumstances where the studies were conducted. CONCLUSIONS: Companion animals are potential reservoirs of drug-resistant uropathogens. Judicious use of antibiotics is necessary to maintain the efficacy of antimicrobials in human and veterinary medicine. Antimicrobial susceptibility monitoring programmes are therefore essential to facilitate the choice of antimicrobial agent that is most likely to be effective, particularly in cases of prior antimicrobial treatment.

Pseudomonas aeruginosa variants obtained from veterinary clinical samples reveal a role for cyclic di-GMP in biofilm formation and colony morphology.

Overuse of antibiotics is contributing to an emerging antimicrobial resistance crisis. To better understand how bacteria adapt tolerance and resist antibiotic treatment, Pseudomonas aeruginosa isolates obtained from infection sites sampled from companion animals were collected and evaluated for phenotypic differences. Selected pairs of clonal isolates were obtained from individual infection samples and were assessed for antibiotic susceptibility, cyclic di-GMP levels, biofilm production, motility and genetic-relatedness. A total of 18 samples from equine, feline and canine origin were characterized. A sample from canine otitis media produced a phenotypically heterogeneous pair of P. aeruginosa isolates, 42121A and 42121B, which during growth on culture medium respectively exhibited hyper dye-binding small colony morphology and wild-type phenotypes. Antibiotic susceptibility to gentamicin and ciprofloxacin also differed between this pair of clonal isolates. Sequence analysis of gyrA, a gene known to be involved in ciprofloxacin resistance, indicated that 42121A and 42121B both contained mutations that confer ciprofloxacin resistance, but this did not explain the differences in ciprofloxacin resistance that were observed. Cyclic di-GMP levels also varied between this pair of isolates and were shown to contribute to the observed colony morphology variation and ability to form a biofilm. Our results demonstrate the role of cyclic di-GMP in generating the observed morphological phenotypes that are known to contribute to biofilm-mediated antibiotic tolerance. The generation of phenotypic diversity may go unnoticed during standard diagnostic evaluation, which potentially impacts the therapeutic strategy chosen to treat the corresponding infection and may contribute to the spread of antibiotic resistance.

DNA microarray assay and real-time PCR as useful tools for studying the respiratory tract Mycoplasma populations in young dairy calves.

PURPOSE: With more than 120 species, the genus Mycoplasma is one of the largest taxa in the class Mollicutes, a group of micro-organisms that are characterized by apparent simplicity and to which important animal pathogens belong. Mycoplasmabovis is the most frequently identified pathogenic Mycoplasma in cattle; however, the prevalence of other Mycoplasma species living in calves' airways is poorly understood. The aim of this work was to characterize the respiratory tract mycoplasma populations in calves on one of the largest dairy farms in Italy using a real-time PCR assay and a DNA microarray assay. METHODOLOGY: A total of 49 nasal swabs and 49 trans-tracheal aspirations from non-vaccinated veal calves were analysed. Genomic DNA was extracted from the samples and then tested using a real-time PCR targeting the oppD gene of M. bovis and a DNA microarray that was able to identify more than 70 Mycoplasma species. RESULTS: Forty-two out of 49 calves tested positive for Mycoplasma spp. (85.7 %). None of the samples tested positive for M. bovis. A majority (73.5 %) of the 98 samples tested positive for M. dispar, while 8 samples tested positive for M. bovirhinis (8.2 %). CONCLUSION: Our results expand our knowledge regarding the diversity of Mycoplasma populations in the respiratory airways of very young veal calves and add data regarding M. bovis prevalence in the Italian cattle population. However, the importance of these species in the respiratory diseases of calves still remains to be determined.

Prevalence of Escherichia coli O157 Shedding in Preweaned Calves on Colorado Dairies.

To gain insight into a potential age-related predisposition for Escherichia coli pathogen shedding on dairies, this pilot study measured the prevalence of E. coli O157 (ECO157) in the feces of preweaned dairy calves. An aim of this study was to link these outcomes with the concurrent environmental presence of ECO157 and dam ECO157 shedding elucidated in a parallel study. Recto-anal mucosal swabs and a subset of fecal grab samples were collected from calves (2 to 8 weeks of age; n = 399) monthly between December 2013 and June 2014 on three dairies in northern Colorado. A subset of calf dams (n = 111) were also sampled via fecal grab. Concurrently, environmental samples were collected from locations within the vicinity of the calves: farm tractor tires, steering wheels, hutches, buckets, and gloves from the research technicians and the employees involved in calf rearing. The presence of ECO157 and virulence genes was measured in the samples and confirmed via PCR. Of the calves, only 1 (0.25%) of 399 individuals shed during the time period, and the ECO157 strain detected carried no measured virulence genes (eaeA, stx1, and stx2). No difference was seen in detection between the recto-anal mucosal swabs and the fecal grab technique. In contrast, 32% (35 of 111) of the dams shed ECO157, with 1.8% (2 of 111) of the shed isolates containing virulence genes. No ECO157 was detected in the environmental samples. These outcomes demonstrate a disparity between dam and calf ECO157 shedding and indicate that preweaned calves, managed similarly to those of this study, probably have a minor influence on dairy contamination and the transmission of ECO157.

Antimicrobial Resistance Profiles in Escherichia coli O157 Isolates from Northern Colorado Dairies.

Escherichia coli O157 (EcO157) infections can lead to serious disease and death in humans. Although the ecology of EcO157 is complex, ruminant animals serve as an important reservoir for human infection. Dairy cattle are unique because they may be a source of contamination for milk, meat, and manure-fertilized crops. Foodborne dairy pathogens such as EcO157 are of primary importance to public health. Antimicrobial resistance (AMR) is a complex phenomenon that complicates the treatment of serious bacterial infections and is of increasing concern. In the face of recommended use restrictions for antimicrobial agents in livestock operations, current AMR patterns in known foodborne pathogens should be documented. The objective of this study was to document AMR patterns in EcO157 isolates from dairies in northern Colorado using antimicrobial agents commonly found on dairies and representative of medically important antimicrobial drug classes. Seventy-five EcO157 isolates were recovered from three dairies. Six isolates were resistant to at least 1 of the 10 tested antimicrobial agents: four were resistant to streptomycin, sulfisoxazole, and tetracycline; one was resistant to streptomycin and tetracycline; and one was resistant to only tetracycline. All resistant isolates were from a single dairy. Overall, a low prevalence (8%) of AMR was observed among the 75 EcO157 isolates. No significant effects on AMR profiles due to virulence genes, parity, or previous antimicrobial treatments within the current lactation period were detected. The results of this study provide background information for future comparative studies investigating AMR trends. Future studies should include more participating farms and more samples and should control for potential confounding factors of AMR that may underlie individual farm variation.

The effects of omeprazole therapy on bacterial colonization of the pharynx in healthy dogs.

OBJECTIVE: To identify the relative abundance of commensal pharyngeal flora in healthy dogs and determine if abundance of pharyngeal flora is altered during omeprazole administration. ANIMALS: Eight adult Beagles. PROCEDURES: A total of 3 baseline pharyngeal swabs, collected 48 hours apart, were obtained from each dog. Omeprazole (1 mg/kg PO q 24 h) was administered for a total of 12 days. During omeprazole administration, pharyngeal swabs were obtained on Days 8, 10, and 12. All swabs were submitted for semiquantitative aerobic and anaerobic culture. Growth of bacterial isolates, as well as genus of isolates, was compared between the pretreatment (n = 24) and treatment (n = 24) swabs. RESULTS: A greater abundance of several bacterial species was identified during the treatment period, including coagulase-negative Staphylococcus (P < 0.01), Bacillus (P < 0.01), and Pasteurella (P = 0.05). The abundance of bacterial species in samples collected during the treatment period was unchanged for Escherichia coli (P = 0.16), Provotella (P = 0.40), hemolytic Streptococcus (P = 0.34), and nonhemolytic Streptococcus (P = 0.14). CONCLUSIONS AND CLINICAL RELEVANCE: This small study indicates that shifts in canine pharyngeal flora may occur during omeprazole therapy. Further studies are warranted to determine the clinical significance of gastric acid suppressants on pharyngeal flora in dogs.

Mechanisms of antimicrobial resistant Salmonella enterica transmission associated with starling-livestock interactions.

Bird-livestock interactions have been implicated as potential sources for bacteria within concentrated animal feeding operations (CAFO). European starlings (Sturnus vulgaris) in particular are known to contaminate cattle feed and water with Salmonella enterica through their fecal waste. We propose that fecal waste is not the only mechanisms through which starlings introduce S. enterica to CAFO. The goal of this study was to assess if starlings can mechanically move S. enterica. We define mechanical movement as the transportation of media containing S. enterica, on the exterior of starlings within CAFO. We collected 100 starlings and obtained external wash and gastrointestinal tract (GI) samples. We also collected 100 samples from animal pens. Within each pen we collected one cattle fecal, feed, and water trough sample. Isolates from all S. enterica positive samples were subjected to antimicrobial susceptibility testing. All sample types, including 17% of external starling wash samples, contained S. enterica. All sample types had at least one antimicrobial resistant (AMR) isolate and starling GI samples harbored multidrug resistant S. enterica. The serotypes isolated from the starling external wash samples were all found in the farm environment and 11.8% (2/17) of isolates from positive starling external wash samples were resistant to at least one class of antibiotics. This study provides evidence of a potential mechanism of wildlife introduced microbial contamination in CAFO. Mechanical movement of microbiological hazards, by starlings, should be considered a potential source of bacteria that is of concern to veterinary, environmental and public health.

Molecular characterization of Salmonella enterica isolates associated with starling-livestock interactions.

Bird-livestock interactions have been implicated as potential sources for bacteria within concentrated animal feeding operations (CAFO). In this study we characterized XbaI-digested genomic DNA from Salmonella enterica using pulsed-field gel electrophoresis (PFGE). The PFGE analysis was conducted using 182 S. enterica isolates collected from a single CAFO between 2009 and 2012. Samples collected in 2012 were subjected to antimicrobial susceptibility testing. The analysis was limited to S. enterica serotypes, with at least 10 isolates, known to occur in both European starlings (Sturnus vulgaris) and cattle (Bos taurus) within this CAFO. A total of five different serotypes were screened; S. Anatum, S. Kentucky, S. Meleagridis, S. Montevideo, S. Muenchen. These samples were recovered from five different sample types; starling gastrointestinal tracts (GI), starling external wash, cattle feces, cattle feed and cattle water troughs. Indistinguishable S. enterica PFGE profiles were recovered from isolates originating in all sample types. Antimicrobial resistance (AMR) was also associated with indistinguishable S. enterica isolates recovered from all samples types. These data suggests that AMR S. enterica is transmitted between cattle and starlings and that shared feed sources are likely contributing to infections within both species. Moreover we isolated indistinguishable PFGE profiles across all years of data collection, suggesting long-term environmental persistence may be mediated by starling visits to CAFO.

Pilot study to evaluate the role of Mycoplasma species in cat bite abscesses.

Mycoplasma species are common inhabitants of the feline oral cavity, and so likely contaminate many cat bite abscesses. The objectives of this study were to determine whether Mycoplasma species are common contaminants of cat bite abscesses and whether they are are associated with ß-lactam-resistant clinical disease. Twenty-six privately owned cats with clinical evidence of an abscess suspected to be from a cat bite were included in the study. Samples from each cat were evaluated by aerobic and anaerobic culture, as well as Mycoplasma species culture and polymerase chain reaction (PCR). All cats were initially treated with appropriate wound management and were administered an antibiotic of the ß-lactam class (amoxicillin, amoxicillin clavulanate or cefovecin sodium). Mycoplasma species DNA was amplified by PCR from 4/26 samples (15.4%); one of these cases was concurrently culture positive. Adequate DNA for sequencing was present for 2/4 positive PCR samples; one was most homologous with Mycoplasma felis, and the other was most homologous with Mycoplasma equigenitalium and Mycoplasma elephantis. Of the 26 cats, 25 responded to the initial treatment by day 7. The cat that failed initial treatment was positive for M equigenitalium or M elephantis DNA on days 0 and 12, and ultimately responded to administration of enrofloxacin and clindamycin. The results suggest that while Mycoplasma species can contaminate cat bite abscesses, routine wound management and ß-lactam antibiotic therapy is adequate for treatment in most cases of abscess. However, as Mycoplasma species infections do not respond to ß-lactam class antibiotic therapy, these organisms should be on the differential list for cats with abscesses that fail treatment with this antibiotic class.

Corynebacterium spp. in dogs and cats with otitis externa and/or media: a retrospective study.

The role of Corynebacterium spp. in the pathogenesis of canine and feline otitis externa/media and their appropriate antimicrobial therapy are unclear. The objectives of this study were to (1) better establish the pathogenicity of Corynebacterium spp. in otitis utilizing reported criteria and by assessing clinical response to antibiotic therapy and (2) to determine the antimicrobial susceptibility patterns of Corynebacterium spp. associated with otitis. The study was retrospective, targeting cultures positive for Corynebacterium spp. Corynebacterium spp. were part of mixed microbial populations in 79/81 cultures. Corynebacterium spp. pathogenicity was highly questionable because of their almost invariable presence with other microbes and the observation that Corynebacterium spp. usually disappear from the ear with resolution of other infections, even when the Corynebacterium spp. are resistant to the prescribed antibiotic(s). However, 2/81 cultures came from two canine ears wherein Corynebacterium spp. may have been pathogenic. Antimicrobial sensitivities for Corynebacterium spp. were available for 54 isolates. Most isolates were susceptible to chloramphenicol (53/54), amikacin (50/54), tetracycline (50/54), gentamicin (46/54), and enrofloxacin (32/54). Among those antibiotics available in otic products, gentamicin and enrofloxacin would be rational choices for the empirical, topical therapy of Corynebacterium spp.

Efficacy of European starling control to reduce Salmonella enterica contamination in a concentrated animal feeding operation in the Texas panhandle.

BACKGROUND: European starlings (Sturnus vulgaris) are an invasive bird species known to cause damage to plant and animal agriculture. New evidence suggests starlings may also contribute to the maintenance and spread of diseases within livestock facilities. Identifying and mitigating the risk pathways that contribute to disease in livestock is necessary to reduce production losses and contamination of human food products. To better understand the impact starlings have on disease transmission to cattle we assessed the efficacy of starling control as a tool to reduce Salmonella enterica within a concentrated animal feeding operation. We matched a large facility, slated for operational control using DRC-1339 (3-chloro-4-methylaniline hydrochloride, also 3-chloro p-toluidine hydrochloride, 3-chloro-4-methylaniline), with a comparable reference facility that was not controlling birds. In both facilities, we sampled cattle feed, cattle water and cattle feces for S. enterica before and after starling control operations. RESULTS: Within the starling-controlled CAFO, detections of S. enterica contamination disappeared from feed bunks and substantially declined within water troughs following starling control operations. Within the reference facility, detections of S. enterica contamination increased substantially within feed bunks and water troughs. Starling control was not observed to reduce prevalence of S. enterica in the cattle herd. Following starling control operations, herd prevalence of S. enterica increased on the reference facility but herd prevalence of S. enterica on the starling-controlled CAFO stayed at pretreatment levels. CONCLUSIONS: Within the starling-controlled facility detections of S. enterica disappeared from feed bunks and substantially declined within water troughs following control operations. Since cattle feed and water are obvious routes for the ingestion of S. enterica, starling control shows promise as a tool to help livestock producers manage disease. Yet, we do not believe starling control should be used as a stand alone tool to reduce S. enterica infections. Rather starling control could be used as part of a comprehensive disease management plan for concentrated animal feeding operations.

Effects of restricted antimicrobial exposure on antimicrobial resistance in fecal Escherichia coli from feedlot cattle.

OBJECTIVES: The primary objective was to evaluate differences in antimicrobial resistance among enteric bacteria recovered from feedlot cattle that were being raised without exposure to antimicrobial drugs (AMDs) and those reared using conventional practices. MATERIALS: Forty pens of feedlot cattle (4557 total animals) that were being fed without AMD exposures were selected for enrollment as were 44 pens of cattle (4913 total animals) being fed for production of conventional beef products at the same feedlots. Fecal samples were collected from the floors of pens approximately biweekly through the middle of the feeding period and again prior to slaughter. Samples were cultured to recover nontype-specific Escherichia coli (NTSEC) and Salmonella enterica, and isolates were evaluated for susceptibility to a panel of AMDs. RESULTS: Cattle enrolled in the study did not differ between groups in entry weight or finish weight, but cattle with restricted AMD and hormone exposures were fed for an average of 50 days longer than conventionally reared cattle (p < 0.001). Resistance among NTSEC isolates was most common to tetracycline, streptomycin, and sulfamethoxazole, and there were slightly higher prevalence of resistance among NTSEC isolates recovered from conventionally reared cattle. Therapeutic AMD exposures did not have a detectable impact on the prevalence of resistance among NTSEC. Although there were detectable temporal trends through the feeding period for resistance to tetracycline, naladixic acid, chloramphenicol, and cephalothin, the direction of trends differed among drugs and these trends were not associated with study groups. S. enterica was recovered rarely (0.73%) but at similar prevalences from cattle with both rearing methods. CONCLUSIONS: These findings suggest that conventional feedlot production methods (including parenteral and in-feed use of AMDs) do not predictably or uniformly increase the prevalence of antimicrobial resistance among fecal NTSEC when compared with rearing methods that restrict exposure to AMDs.

Characterization of genes encoding virulence determinants and toxins in Staphylococcus aureus from bovine milk in Central Italy.

The aim of this study was to evaluate the genotypic characteristics of Staphylococcus aureus isolates (n=170) from bovine milk collected from seven dairy farms in Italy. On the basis of cultural and biochemical properties and by amplification of the 23S rRNA specific to S. aureus, all isolates were identified as S. aureus. To genotypically characterize S. aureus isolates, genes encoding virulence determinants (nuc, clfA, spa-IgG-binding, spa-X-region, fnbA and fnbB, cap5 and cap8) and staphylococcal enterotoxins (sea, seb, sec, sed, see, seg, seh, sei, sej) were investigated using a PCR technique. The results showed that the isolates of S. aureus in each farm had the same genotypic characteristics, while the isolates genotipically differed between the different farms. The present study might help to understand the distribution of prevalent S. aureus strains in dairy farms.

Hemolytic-uremic syndrome in a postpartum mare concurrent with encephalopathy in the neonatal foal.

A postpartum mare and foal were presented for evaluation of fever and lethargy in the mare. The mare was diagnosed with endometritis and initially responded well to treatment. On the second day of hospitalization, the mare developed renal insufficiency characterized by oliguria, azotemia, hemolysis, and thrombocytopenia. Concurrently, the foal developed rapidly progressive central nervous system signs culminating in refractory seizures. Both animals failed to respond to treatment and were euthanized. Thrombotic microangiopathy involving glomeruli was evident on microscopic examination of the mare's kidneys. Microscopic evidence of brain edema was the principal postmortem finding in the foal. No specific etiology was confirmed in either case. Notably, Escherichia coli 0103:H2 was isolated from the mare's uterus and the gastrointestinal tracts of both animals. To the authors' knowledge, this is the first report in which an organism implicated as a cause of hemolytic-uremic syndrome was isolated from an animal with clinical signs and postmortem findings consistent with the disease.

Isolation of Vibrio cholerae from the brain of a feedlot heifer with meningoencephalitis.

A 700-pound, 9-month-old Angus heifer from a feedlot presented with acute neurologic signs, characterized by circling, posterior weakness, and nonresponsiveness, followed by death. Histologically, the frontal lobe and the thalamus contained multiple foci of liquefaction that contained numerous degenerative neutrophils and foamy macrophages. Some of these foci were centered on blood vessels that contained fibrin thrombi and exhibited varying degrees of fibrinoid necrosis of the vessel wall. There was adjacent axonal degeneration and neuronal necrosis characterized by pronounced cytoplasmic eosinophilia, peripheralization of the nuclei, and loss of Nissl substance. Aerobic culture of the brain yielded moderate growth of Vibrio species, which was determined to be Vibrio cholerae by polymerase chain reaction analysis of a 438-base pair fragment of the 16 S ribosomal RNA gene. V. cholerae are motile, gram-negative, curved rod-shaped bacteria. Some strains of V. cholerae are important food- and water-borne bacterial pathogens that produce an often fatal diarrhea in humans. This is the first known case report of V. cholerae meningoencephalitis and cerebral abscessation in a bovine.

Impact of hospitalization and antimicrobial drug administration on antimicrobial susceptibility patterns of commensal Escherichia coli isolated from the feces of horses.

Objective-To evaluate antimicrobial susceptibility of commensal Escherichia coli strains isolated from the feces of horses and investigate relationships with hospitalization and antimicrobial drug (AMD) administration. Design-Observational study. Animals-68 hospitalized horses that had been treated with AMDs for at least 3 days (HOSP-AMD group), 63 hospitalized horses that had not received AMDs for at least 4 days (HOSP-NOAMD group), and 85 healthy horses that had not been hospitalized or treated with AMDs (community group). Procedures-Fecal samples were submitted for bacterial culture, and up to 3 E coli colonies were recovered from each sample. Antimicrobial susceptibility of 724 isolates was evaluated. Prevalence of resistance was compared among groups by use of log-linear modeling. Results-For 12 of the 15 AMDs evaluated, prevalence of antimicrobial resistance differed significantly among groups, with prevalence being highest among isolates from the HOSP-AMD group and lowest among isolates from the community group. Isolates recovered from the HOSP-AMD and HOSP-NOAMD groups were also significantly more likely to be resistant to multiple AMDs. Resistance to sulfamethoxazole and resistance to trimethoprim-sulfamethoxazole were most common, followed by resistance to gentamicin and resistance to tetracycline. Use of a potentiated sulfonamide, aminoglycosides, cephalosporins, or metronidazole was positively associated with resistance to 1 or more AMDs, but use of penicillins was not associated with increased risk of resistance to AMDs. Conclusion and Clinical Relevance-Results suggest that both hospitalization and AMD administration were associated with prevalence of antimicrobial resistance among E coli strains isolated from the feces of horses.