Background and Objectives: Due to the widespread distribution of Listeria monocytogenes in environmental and animal sources and serious clinical complications in human, this study was aimed to isolate L. monocytogenes from water and clin- ical specimens by culture and PCR methods and to investigate the presence of hlyA and inlA virulence genes. Materials and Methods: Water and clinical samples of vaginal and fecal were screened for the presence of L. monocyto- genes by phenotypic and standard biochemical tests. PCR amplification was performed on extracted DNA using primers based on the hlyA and inlA genes. A 733-bp fragment of inlA gene was used for investigation of polymorphism using RFLP analysis. Results: In total, 45 phenotypically and molecularly confirmed L. monocytogenes strains were isolated from different sourc- es including 30 (16.7%) from water, 9 (11.3%) from vaginal swabs and 6 (7.5%) from fecal samples. RFLP analysis of PCR products using AluI and Tsp509I restriction enzymes, generated two profiles with 8 to 10 bands ranging in size from 15 to 210 bp. The majority of water and clinical isolates were classified in profile 2. Conclusion: We demonstrated 45 L. monocytogenes isolates from tested water and clinical samples by phenotypic and mo- lecular tests. The majority of the isolates were classified in the same RFLP profile, showing the water as a potential source of clinical complications in patients in the region of study.

Background: Listeria monocytogenes is a facultative intracellular pathogen thought to be widely distributed in the environment. Listeriolysin O (LLO) and internalin A are two major pathogenesis factors in this bacterium. Objectives: The purpose of this research was to isolate of Listeria from different parts of the Karun river in Iran. The bacteria were identified based on cultural characteristics, biochemical tests and by PCR assay. Materials and Methods: A total of 150 water samples from Karun river (rural and urban environment) were collected. The bacteria were identified based on cultural characteristics, biochemical tests and by PCR assay. Results: From total 150 samples, twenty L. monocytogenes were isolated and identified and amplification of two pathogenicity genes: hlyA and inlA in twenty L. monocytogenes were positive. Conclusions: Detection of Listeria monocytogenes with hlyA and inlA genes suggest that these strains may have the potential to invade host cells, and consumption of water contaminated with L. monocytogenes, can cause human disease.

Background: Antibiotic resistance among bacteria is a worldwide problem. Enterobacteriaceae resistance to third-generation cephalosporins is typically caused by the production of β-lactamases. Objectives: The aim of this study was to determine antimicrobial susceptibility of environmental Enterobacteriaceae isolates from Karun River in Iran. Materials and Methods: A total of 600 water samples were collected from nine stations along Karun River in Iran, during spring and summer of 2012. In this research, different waterborne bacterial pathogens were isolated and identified using the membrane filtration technique and analytical profile index system for Enterobacteriaceae (API 20E). Then, disk diffusion method (CLSI, 2010; M2-A9) was used for testing the antibiotic resistance susceptibility. Enterobacteriaceae genera were tested against sixteen antibiotics: ampicillin, carbencillin, methicillin, cephalothin, cefotaxime, vancomycin, amikacin, ofloxacin, kanamycin, tetracycline, erythromycin, clindamycin, norfloxacin, nitrofurantoin, chloramphenicol, and amoxycillin. Results: The results of this study suggested that the level of fecal contamination in Karun water was very high. Among the isolated Enterobacteriaceae, there were 287 strains of (65%) Escherichia coli, 162 (27%) Enterobacter aeogenes, 73 (12.16%) Citrobacter freundii, 58 (9.66%) Proteus vulgaris, and 20 (3.3%) Salmonella typhi. All Enterobacteriaceae isolates showed 100% resistance to ampicillin, carbenicillin, methicillin, vancomycin, erythromycin, clindamycin, and tetracycline. They failed to exhibit resistance to norfloxacin and ofloxacin. Other antibiotics showed intermediate activity, and some isolates were resistant. Conclusions: Detection of fecal indicator bacteria (E. coli) in more than 75% of water samples indicates the possible presence of other bacteria causing infectious diseases.