Veterinary Research Forum

Abstract An emerging global threat is the development of resistance to various antibiotic groups among pathogenic bacteria, including Pasteurella multocida. The excessive use of antibiotics and presence of antibiotic resistance carriers play a significant role in the development of multiple resistances to anti-microbial agents. Given the role and importance of plasmids in the development of antibiotic resistance, it is important to prevent the transfer, replication, and multiplication of plasmids by eliminating plasmids. In this study, the role of plasmids in the development and transmission of antibiotic resistance in P. multocida was investigated and evaluated. This study was performed on P. multocida isolates collected from apparently healthy and ailing animals (February to September 2014). Identification of P. multocida isolates was carried out using standard biochemical tests and kmt1 gene amplification. After initial tests and plasmid DNA extraction, five plasmid-containing isolates were selected for further work. To compare antibiotic resistance after plasmid removal, the disk diffusion method was used. Based on the results, it was determined that all plasmid-containing isolates that showed a high level of antibiotic resistance (especially with large plasmids) became sensitive to anti-microbial agents after plasmid removal. Therefore, according to the findings, the role and importance of plasmids in the development of antibiotic resistance in P. multocida was determined. It was also found in this study that the existence and persistence of plasmids by P. multocida bacteria was of great importance in the role of plasmids in the development of antibiotic resistance.

Abstract Pasteurella multocida exists as a commensal in the upper respiratory tracts of livestock, and poultry, and causes a wide variety of diseases in humans and animals. This study aimed to investigate the incidence of P. multocida by bacteriological and molecular characterization in sheep and goats and screening the existence of capsule-specific genes and their antibiotic resistance pattern. Totally, 1650 nasopharyngeal swabs were collected from apparently healthy sheep and goats and 460 lung tissues were collected from slaughtered animals in Fars province, Iran. All samples were cultured and suspected colonies were examined by biochemical tests, antimicrobial assay and polymerase chain reaction (PCR). Among 165 P. multocida (104 sheep and 61 goats) isolates, the capA, capD, and capB genes were amplified in 98, 48, and 12 isolates, respectively. The occurrence of four virulence-associated genes of P. multocida isolates were determined by PCR. Most isolates harbored the toxA (79.40%) and hgbB genes (70.90%) and 59.40% of isolates had the pfhA gene. Almost half of the isolates (46.10%) contained the tbpA gene. According to the current study, P. multocida capsular type A had the most frequency followed by type D. In addition, the high frequency of tbpA, pfhA, toxA, and hgbB genes revealed that these genes are possibly important in the pathogenesis of P. multocida. Oxytetracycline, enrofloxacin, florfenicol, and tilmicosin were the most effective drugs.

Abstract Pasteurella multocida a Gram-negative bacterium exists as a commensal in the upper respiratory tracts of livestock, and poultry. It is causative agent of a range of diseases in mammals and birds including fowl cholera in poultry, atrophic rhinitis in pigs and bovine hemorrhagic septicemia in cattle and buffalo. This study aimed to isolate P. multocida from sheep and cattle lungs sampled and assessed by bacteriological procedures and pulse field gel electrophoresis (PFGE) characterization. In this study 52 isolated of P. multocida were obtained (2016-2017) from clinically healthy and diseased animals (sheep and cattle) evaluated by PFGE for determining the relationship between them. According to the results of this study 12 sheep isolates had similarities above 94.00% and two cattle isolates showed similarities above 94.00%. When compared between sheep and cattle, most isolates showed a similarity of less than 50.00% indicating the great differences between isolates. It is noteworthy that in the present study, performed by PFGE to determine the type of P. multocida isolates, a very high distinction was made to determine the type of isolates and the relationship between isolates based on fragments in their genome using enzymes.

Abstract Althoughpoultry meat is considered as the main source for human Campylobacter infections,there is limited information about non-poultry sources. The present study was aimed to investigate the prevalence and the antibiotic resistance of thermophilic Campylobacter spp. in fecal samples of the cattle and sheep in Shiraz, Iran. A total of 302fecal samples were obtained from clinically healthy, slaughtered cattle and sheep from Shiraz slaughterhouse. The animals were clinically healthy before being slaughtered. The samples were cultured according to the specific cultivation method under thermophilic conditions. The susceptibility of Campylobacter isolates were determined for 13 antimicrobial agents. All enriched samples and cultured isolates were targeted for polymerase chain reaction (PCR) detection of 16S rRNA and multiplex PCR for determining their species. Among 302 fecal samples, 65 (21.5%) and 205 (67.8%) samples were positive for the presence of Campylobacter species with the cultivation and PCR techniques, respectively. All 65 distinct isolates were susceptible to neomycin and colistin and the isolates showed high resistance to cephalotin (83.0%) and ciprofloxacin (67.7%). After the multiplex PCR, 78.5% of total positive samples showed the simultaneous presence of Campylobacter jejuni and Campylobacter coli. In conclusion, the results emphasized that non-poultry farms are important as a possible source of Campylobacter infections.

Abstract Shiga toxin-producing Escherichia coli (STEC) are food-borne pathogens primarily associated with the consumption of contaminated ground beef and are an important food safety concern worldwide. STEC has been found to produce a family of related cytotoxins known as Shiga toxins (Stxs). Shiga toxins have been classified into two major classes, Stx1 and Stx2. A single strains of STEC can produce Stx1, Stx2 (or its variants) or both. The aims of this project were to determine the prevalence and molecular characteristics of STEC isolates from chicken flocks in Northwest of Iran. A total of 350 fecal samples from 28 broiler farms were screened for the presence of STEC by conventional culture methods and polymerase chain reaction (PCR). All samples were initially subjected to phenotypical analysis using the Sorbitol MacConkey agar plate for the detection of the sorbitol negative E. coli, and then for genotypic analysis, by multiplex PCR for detection of stx1and stx2 genes. STEC were isolated from 14 (4 %) chicken fecal samples. To our knowledge, this is the first report of isolation of STEC from poultry in Iran. To conclude, this work revealed the presence STEC strains harboring stx1 and stx2 gene in healthy chicken fecal samples in Northwest of Iran suggesting they can play as an important potential source of contamination for people working on broiler farms or are in contact with chicken carcasses at meat processing plants.