Few antimicrobials are licensed for use in sheep in Canada, and the range of indications is narrow. Treatment in an “extra-label” manner may be ineffective. In addition, potentially harmful drug residues in food-animal products and antimicrobial resistance in bacteria may be associated with extra-label drug use (ELDU). No data had been documented on drug use, specifically antimicrobial use (AMU), in Ontario sheep, although it was thought that much use was extra-label. This study investigated AMU and ELDU on 49 lamb-producing Ontario sheep farms. Data were prospectively collected over 12 months from the participating farms, and farm-level practices were ascertained with a questionnaire. Treatment-level and farm-level variables were investigated for associations with rates of AMU by means of Poisson rate regression models fit with a generalized estimating equation to control for clustering at the farm level. Antimicrobials with high mean exposure rates included chlortetracycline (in feed), penicillins, and oxytetracycline. The exposure rate in lambs was significantly lower (P < 0.01) with antimicrobial treatment of systemic signs, respiratory disease, or wound or injury than with treatment of other reported diseases or conditions; it was also significantly lower with 3 or more lambing periods per year (α = 0.05). The exposure rate in adult sheep was significantly lower with treatment of 5 of the 6 most prevalent diseases or conditions (α = 0.05) and significantly higher with producer decision to treat and producer experience of 20 y or greater. Rates of using antimicrobials not licensed for use in sheep were high, as was extra-label use of licensed antimicrobials. Diseases reportedly treated most often with antimicrobials (e.g., systemic signs, mastitis) were significantly associated with lower rates of ELDU (α = 0.05). Compared with the rates in adult sheep, the mean rate of use of nonlicensed antimicrobials was similar in the lambs, whereas the mean rate of extra-label use of licensed antimicrobials was lower among the lambs. The results are useful in determining if public health concerns about antimicrobial use in Ontario sheep are warranted and in creating drug use and licensure strategies for the Canadian sheep industry.

Objective--To evaluate effects of a Salmonella Newport siderophore receptor and porin protein (SRP) vaccine on cattle health and performance and on prevalence of fecal shedding of Salmonella bacteria in feedlot cattle. Animals--1,591 beef cattle. Procedures--Cattle were randomly allocated within a replicate (n = 10 replicates [20 total pens]), administered 2 mL of a Salmonella Newport SRP vaccine (n = 795 cattle) or a placebo (796), and revaccinated approximately 21 days after the first administration. Health and performance data were recorded by trained feedlot personnel who were blinded to treatment. Fresh fecal samples (n = 25) were collected from pen floors on days 0, 60, and 120 and within 24 hours of cattle harvest and were subjected to selective Salmonella culture and serotyping by laboratory personnel who were blinded to treatment. Pen-level mixed models were used to analyze data. Results--Significant differences in fecal prevalence of Salmonella bacteria or health and performance variables were not detected between vaccinated and control cattle. Salmonella bacteria were recovered from all 10 replicates, and cumulative prevalence estimates ranged from 1.5% to 22%. Overall prevalence of fecal shedding of Salmonella bacteria was 10.2% and 10.9% in vaccinated and control cattle, respectively. Overall morbidity risk was 34.8% for both vaccinated and control cattle. Overall mortality risks were 1.9% and 1.1% for vaccinated and control cattle, respectively. Conclusions and Clinical Relevance--In this setting, administration of the Salmonella Newport SRP vaccine in feedlot cattle had no effect on fecal prevalence of Salmonella bacteria or cattle health and performance.

Objective—To evaluate the elimination pharmacokinetics of a single IM injection of a long-acting ceftiofur preparation (ceftiofur crystalline-free acid [CCFA]) in healthy adult helmeted guineafowl (Numida meleagris). Animals—14 healthy adult guineafowl. Procedures—1 dose of CCFA (10 mg/kg) was administered IM to each of the guineafowl. Blood samples were collected intermittently via jugular venipuncture over a 144-hour period. Concentrations of ceftiofur and all desfuroylceftiofur metabolites were measured in plasma via high-performance liquid chromatography. Results—No adverse effects of drug administration or blood collection were observed in any bird. The minimal inhibitory concentration (MIC) for many bacterial pathogens of poultry and domestic ducks (1 μg/mL) was achieved by 1 hour after administration in most birds and by 2 hours in all birds. A maximum plasma concentration of 5.26 μg/mL was reached 19.3 hours after administration. Plasma concentrations remained higher than the MIC for at least 56 hours in all birds and for at least 72 hours in all but 2 birds. The harmonic mean ± pseudo-SD terminal half-life of ceftiofur was 29.0 ± 4.93 hours. The mean area under the curve was 306 ± 69.3 μg•h/mL, with a mean residence time of 52.0 ± 8.43 hours. Conclusions and Clinical Relevance—A dosage of 10 mg of CCFA/kg, IM, every 72 hours in helmeted guineafowl should provide a sufficient plasma drug concentration to inhibit growth of bacteria with an MIC ≤ 1 μg/mL. Clinical use should ideally be based on bacterial culture and antimicrobial susceptibility data and awareness that use of CCFA in avian patients constitutes extralabel use of this product.

It is important to identify the bacteria in snakes because they can cause disease; importantly, bacteria such as Stenotrophomonas maltophilia, Escherichia coli, Proteus vulgaris etc. could be pathogens especially in hospitalized, debilitated hosts, and immunocompromised patients. To analyze the distribution of snakes' bacteria in petting zoo, samples from 20 snakes were collected from 2002 to 2008. Nine bacteria species were isolated from both oral and cloaca while four and six species were identified only from oral and cloaca, respectively. Except for Actinobacter sp., all of the identified strains are opportunistic pathogens, and most of them can cause nosocomial infections in humans. Present results indicate that prevalence of various zoonotic bacterial strains in snakes could be involved in potential transfer of these bacteria into caretakers and other animals. Therefore, it needs to examine the antibiotic resistance of these pathogens to prevent outbreaks.

Objective—To evaluate the impact of oxytetracycline exposure on horizontal transfer of an antimicrobial resistance plasmid. Sample—Populations of Salmonella enterica subsp enterica serovar Typhimurium and Escherichia coli. Procedures—Mixed populations of plasmid donor (Salmonella Typhimurium) and recipient (E coli) bacteria were assigned to 1 of 2 simulated oxytetracycline dosing regimens (high peak concentration-short elimination half-life [HC-SHL] or low peak concentration—long elimination half-life [LC-LHL]) or served as untreated control replicates. Donor, recipient, and transconjugant (E coli that acquired the plasmid) bacteria populations were quantified at 12, 24, and 36 hours after oxytetracycline administration by use of culture on selective bacterial growth media. Results—The ratio of transconjugant to donor bacteria was significantly reduced in the oxytetracycline-exposed replicates, compared with the ratio for the control replicates, at 12 hours. At 24 and 36 hours, results for the HC-SHL regimens were not significantly different from results for the respective control replicates, and results for the LC-LHL regimens also were not significantly different from results for the respective control replicates. The oxytetracycline concentration at these time points (12 hours in the HC-SHL regimen and all 3 time points in the LC-LHL regimen) were in excess of the minimum inhibitory concentration of the recipient bacteria. Conclusions and Clinical Relevance—Transfer of antimicrobial resistance plasmids may be suppressed in vitro by oxytetracycline exposure at concentrations greater than the minimum inhibitory concentration of the recipient bacteria.

The objectives of this study were to determine the effect of bacterial culture conditions on adherence of enterohemorrhagic Escherichia coli (EHEC) O157:H7 strain 86-24 in vivo to pig enterocytes and to compare the results with adherence in vitro to cultured HEp-2 and IPEC-J2 cells. Growth of O157:H7 in MacConkey broth (MB) resulted in almost no adherence to both HEp-2 and IPEC-J2 cells; prior exposure of the bacteria to pH 2.5 reduced adherence. There was greater adherence by bacteria from static cultures than by those from shaken cultures and by bacteria cultured in brain-heart infusion (BHI) plus NaHCO3 (BHIN) than by bacteria cultured in BHI. In contrast, in pig ileal loops, bacteria cultured in MB adhered well to enterocytes, and prior exposure to pH 2.5 had no effect on adherence. Among several media tested for their effect on bacterial adherence in the pig intestine, MB and BHIN proved to be the best. Bacterial adherence was dose-dependent and was more extensive in the ileum than in the colon. This study demonstrated that there are remarkable differences between culture conditions that promote adherence of an EHEC O157:H7 strain in vitro and in vivo, that culture conditions profoundly affect adherence to epithelial cells in vitro and in vivo, and that pig ileal loops are better suited to adherence studies than are colon loops.

Objective—To investigate the effect of opsonization of Rhodococcus equi with R equi-specific antibodies in plasma on bacterial viability and phagocyte activation in a cell culture model of infection. Sample—Neutrophils and monocyte-derived macrophages from 6 healthy 1-week-old foals and 1 adult horse. Procedures—Foal and adult horse phagocytes were incubated with either opsonized or nonopsonized bacteria. Opsonization was achieved by use of plasma containing high or low concentrations of R equi-specific antibodies. Phagocyte oxidative burst activity was measured by use of flow cytometry, and macrophage tumor necrosis factor (TNF)-α production was measured via an ELISA. Extracellular and intracellular bacterial viability was measured with a novel R equi-luciferase construct that used a luminometer. Results—Opsonized bacteria increased oxidative burst activity in adult horse phagocytes, and neutrophil activity was dependent on the concentration of specific antibody. Secretion of TNF-α was higher in macrophages infected with opsonized bacteria. Opsonization had no significant effect on bacterial viability in macrophages; however, extracellular bacterial viability was decreased in broth containing plasma with R equi-specific antibodies, compared with viability in broth alone. Conclusions and Clinical Relevance—The use of plasma enriched with specific antibodies for the opsonization of R equi increased the activation of phagocytes and decreased bacterial viability in the extracellular space. Although opsonized R equi increased TNF-α secretion and oxidative burst in macrophages, additional factors may be necessary for effective intracellular bacterial killing. These data have suggested a possible role of plasma antibody in protection of foals from R equi pneumonia.

In the study, 348 bacterial isolates comprising of Escherichia coli (100), Klebsiella aerogens (45), Proteus mirablis (35), Peudomonas aerogens (20), Staphylococcus sp. (78), Streptococcus sp. (13), Bacillus sp. (57) were isolated from egg shell and egg contents of 150 egg samples collected from local market in Patna (Bihar). The isolates were subjected to antibiogram. This study demonstrated that egg from organized farm microbial contamination than unorganized poultry farm reflecting the effect of environment, storage and transportation on microbial quality of eggs.

Strangles is an extremely contagious bacterial infection specific to&#xD;equine species( horses, mules and zebras). A nationwide screening of S. equi was conducted among horses following an isolation of Streptococcus equi subsp. equi (S. equi) from a horse. All horses were monitored for the presence of respiratory signs, nasal discharge and submandibular swelling. This paper reports the isolation of S. equi from horses during a nationwide survey from August 2010 to December 2010. From August 2010 to December 2010 our laboratory received 2,825 nasal swabs, 9 guttural pouch flushes, 1 submandibular swab and 1 submandibular abscess. The samples were subjected to conventional bacterial isolation and identification.&#xD;Streptococcus equi-positive samples were also confirmed by detecting the M-gene (SeM) of the bacteria by using PCR. Two nasal swabs from two horses and one submandibular abscess from a horse were positive for S. equi by culture and subsequently by PCR. Surveillance for S. equi should be continued for the control of the strangles. PCR can be carried out in parallel to bacterial culture to increase the&#xD;detection rate of carriers and shedders.