Differences in the pathogenicity of atypical enteropathogenic Escherichia coli (EPEC) strains may be due, at least partially, to different expression patterns of some virulence genes. To investigate this hypothesis, the virulence gene expression patterns of 6 atypical EPEC strains isolated from healthy and diarrheic ruminants were compared using quantitative real-time reverse transcription polymerase chain reaction after growing the bacteria in culture medium alone or after binding it to HeLa epithelial cells. Some virulence genes in strains from diarrheic animals were upregulated relative to their expression in strains from healthy animals. When bacteria were cultured in the presence of HeLa cells, the ehxA and efa1/lifA genes, previously associated with the production of diarrhea, were expressed at higher levels in strains from diarrheic animals than in strains from healthy animals. Thus, the expression levels of some virulence genes may help determine which atypical EPEC strains cause diarrhea in ruminants.

Objective-To assess antimicrobial resistance and transfer of virulence genes facilitated by subtherapeutic concentrations of antimicrobials in swine intestines. Animals-20 anesthetized pigs experimentally inoculated with donor and recipient bacteria. Procedures-4 recipient pathogenic bacteria (Salmonella enterica serotype Typhimurium, Yersinia enterocolitica, Shigella flexneri, or Proteus mirabilis) were incubated with donor bacteria in the presence of subinhibitory concentrations of 1 of 16 antimicrobials in isolated ligated intestinal loops in swine. Donor Escherichia coli contained transferrable antimicrobial resistance or virulence genes. After coincubations, intestinal contents were removed and assessed for pathogens that acquired new antimicrobial resistance or virulence genes following exposure to the subtherapeutic concentrations of antimicrobials. Results-3 antimicrobials (apramycin, lincomycin, and neomycin) enhanced transfer of an antimicrobial resistance plasmid from commensal E coli organisms to Yersinia and Proteus organisms, whereas 7 antimicrobials (florfenicol, hygromycin, penicillin G, roxarsone, sulfamethazine, tetracycline, and tylosin) exacerbated transfer of an integron (Salmonella genomic island 1) from Salmonella organisms to Yersinia organisms. Sulfamethazine induced the transfer of Salmonella pathogenicity island 1 from pathogenic to nonpathogenic Salmonella organisms. Six antimicrobials (bacitracin, carbadox, erythromycin, sulfathiazole, tiamulin, and virginiamycin) did not mediate any transfer events. Sulfamethazine was the only antimicrobial implicated in 2 types of transfer events. Conclusions and Clinical Relevance-10 of 16 antimicrobials at subinhibitory or subtherapeutic concentrations augmented specific antimicrobial resistance or transfer of virulence genes into pathogenic bacteria in isolated intestinal loops in swine. Use of subtherapeutic antimicrobials in animal feed may be associated with unwanted collateral effects.

Objective-To determine the efficacy of decontamination and sterilization of a disposable port intended for use during single-incision laparoscopy. Sample-5 material samples obtained from each of 3 laparoscopic surgery ports. Procedures-Ports were assigned to undergo decontamination and ethylene oxide sterilization without bacterial inoculation (negative control port), with bacterial inoculation (Staphylococcus aureus, Escherichia coli, and Mycobacterium fortuitum) and without decontamination and sterilization (positive control port), or with bacterial inoculation followed by decontamination and ethylene oxide sterilization (treated port). Each port underwent testing 5 times; during each time, a sample of the foam portion of each port was obtained and bacteriologic culture testing was performed. Bacteriologic culture scores were determined for each port sample. Results-None of the treated port samples had positive bacteriologic culture results. All 5 positive control port samples had positive bacteriologic culture results. One negative control port sample had positive bacteriologic culture results; a spore-forming Bacillus sp organism was cultured from that port sample, which was thought to be an environmental contaminant. Bacteriologic culture scores for the treated port samples were significantly lower than those for the positive control port samples. Bacteriologic culture scores for the treated port samples were not significantly different from those for negative control port samples. Conclusions and Clinical Relevance-Results of this study indicated standard procedures for decontamination and sterilization of a single-use port intended for use during singleincision laparoscopic surgery were effective for elimination of inoculated bacteria. Reuse of this port may be safe for laparoscopic surgery of animals.

Hemorrhagic pneumonia can be a major cause of mortality in farmed mink in the fall. In its classic form, hemorrhagic pneumonia is caused by the bacterium Pseudomonas aeruginosa. In recent years, however, outbreaks of this type of pneumonia that are associated with hemolytic Escherichia coli have also occurred in farmed mink. The purpose of this study was to compare histological lesions of acute hemorrhagic pneumonia associated with both P. aeruginosa and E. coli in mink, including a description of tissue distribution of pathogens, in an attempt to differentiate between the 2 disease entities based on histopathology. The study included material submitted for diagnostic investigation to the National Veterinary Institute in Denmark from 2006 to 2009. Altogether, 19 cases of hemorrhagic pneumonia with a pure lung culture of P. aeruginosa and 18 cases of hemorrhagic pneumonia with a pure lung culture of E. coli were examined. Formalin-fixed paraffin-embedded lung tissue obtained from the mink was examined by histology and fluorescence in-situ hybridization (FISH). It was possible to detect a slight histological difference between hemorrhagic pneumonia caused by P. aeruginosa and by E. coli, as P. aeruginosa was most often found surrounding blood vessels and lining the alveoli, while E. coli showed a more diffuse distribution in the lung tissue. Furthermore, P. aeruginosa often elicited a very hemorrhagic response in the lung, while infection with E. coli was associated with a higher frequency of alveolar edema and mild lymphoid cuffing in the lungs.