Shiga toxin producing Escherichia coli is a contaminant of food and water that causes a diarrheal syndrome followed by more severe disease of the kidneys and symptoms of the central nervous system in humans. The isolation of Shiga toxin producing Escherichia coli (STEC) from diarrheic and apparently health calves is difficult due to lack of differential phenotypic characteristics from nonpathogenic Escherichia coli. The improvement of molecular technology allows identification of both toxin and serogroup specific genetic determinants. In this study, 300 fecal samples from diarrheic and apparently healthy calves were screened for STEC using PCR targeting Shiga toxin determinants. In addition routine culture methods for isolating O157 and non O157 STEC were also performed. The screening assays of serotyping isolates revealed 7 (4.1%) of O157H7, 156 (92.8%) of non O157 and 5 (3.1%) for untypable strains. These included STEC serotypes of O157H7 and O26 from diarrheic samples, and O78, O55 and O126 from apparently healthy calves. The high rate of STEC isolation and the diversity of STEC serogroup from calves focus the light on the importance of calves as reservoir of E. coli as well as motivate us to improve biosecurity measures in dairy farms.

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Background and Aim: Wild birds can carry a number of potential human and animal pathogens. These birds can intrude into human habitats giving the opportunity to transmission of such infection. Therefore, the current study was designed to investigate the role of crows and waterfowls as vectors of Salmonella and Listeria monocytogenes and to compare cultivation methods with direct polymerase chain reaction (PCR) for the detection of infection. Materials and Methods: A total of 200 fecal dropping samples were collected. Salmonella was cultivated by three step method (Universal Pre-enrichment Broth [UPB], Rappaport-Vassiliadis Broth, and Xylose Lysine Desoxycholate agar). The recovered isolates were characterized by biotyping, serotyping, and PCR detection of enterotoxin (stn) gene. The antibiogram pattern of isolates against a panel of 8 antibiotics was recorded. L. monocytogenes was cultivated on UPB, then on Listeria Oxford Agar and Listeria CHROMagar. The recovered isolates were characterized by biotyping and PCR detection of listeriolysin (hylA) gene. Results: The percentages of Salmonella infection in crows and waterfowls were 10 and 20, respectively. The most frequently recovered serovars were Typhimurium, Potengi, Enteritidis, and Kentucky. Antimicrobial susceptibility analysis of Salmonella isolates showed that the resistance rates for gentamicin were the highest (92%), followed by amoxicillin (88%) and cefixime (60%). Resistance to 8 antibiotics was recorded in 60% (15/25) of Salmonella isolates. The percentages of L. monocytogenes infection in crows and waterfowls were 1.3 and 2, respectively. Direct PCR applied to UPB revealed that 12% and 3% of samples were positive for Salmonella and L. monocytogenes, respectively, and there was no significant difference between direct PCR and cultivation method for the detection of infection. Conclusion: The present findings indicate that wild birds can harbor zoonotic enteric pathogens and this necessitates monitoring the epidemiologic status of these pathogens among wild birds and humans and applying the appropriate intervention measures to prevent the spread of infection.