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The aim of this study was to evaluate the resistance and virulence characteristics of Yersinia enterocolitica strains of clinical and environmental origins over a 5-year period in Iran and to determine the genetic diversity of strains using pulsed-field gel electrophoresis (PFGE) method. A total of 20 Y. enterocolitica strains were collected from 850 stool samples of patients with diarrhea, and 18 Y e rsinia spp. including 10 Y. enterocolitica were collected from water, food, and vegetable samples. The most frequently isolated Y. enterocolitica strains belonged to biotype (BT) 1A (83.33%). No Y. enterocolitica BT4 was detected that can be attributed to the absence of pig animal reservoir in Iranian food chain. The most frequent chromosomal virulence genes among the Y. enterocolitica isolates were inv (100%), ys tA (67%), ystB (83%), tccC (20%), and ail (17%). The most frequent chromosomal virulence genes among non- enterocolitica Yersinia spp. isolates were ystB (87.5%), ystA (37.5%), and inv (37.5%). None of the Y. enterocolitica isolates harbored plasmid origin virulence genes. None of the isolates was resistant to ciprofloxacin, gentamicin, tetracycline, cotrimoxazole, and chloramphenicol, whereas 90% of the Y. enterocolitica and 62.5% of the Yersinia spp. strains were resistant to ampicillin. PFGE genotyping showed a heterogeneous population of highly susceptible Yersinia spp. in both clinical and environmental samples, putting forward a good prognosis in the treatment of patients with yersiniosis. The occurrence of biotype 1A with inv + ystA + ystB + genotype in clinical strains implies the significance of inv , ystA , and ystB gene products in turning of naturally nonpathogenic biotype 1A strains into clinically important pathogens.

Background: Salmonellosis is a major food-borne disease worldwide. The increasing prevalence of antimicrobial resistance among food-borne pathogens such as Salmonella spp. is concerning., Objective: The main objective of this study is to identify class 1 integron genes and to determine antibiotic resistance patterns among Salmonella isolates from children with diarrhea., Methods: A total of 30 Salmonella isolates were recovered from children with diarrhea. The isolates were characterized for antimicrobial susceptibility and screened for the presence of class 1 integron genes (i.e. intI1, sulI1, and qacEΔ1)., Results: The most prevalent serotype was Enteritidis 36.7%, followed by Paratyphi C (30%), and Typhimurium (16.7%). The highest rates of antibiotic resistance were obtained for nalidixic acid (53.3%), followed by streptomycin (40%), and tetracycline (36.7%). Regarding class 1 integrons, 36.7%, 26.7%, and 33.3% of the isolates carried intI1, SulI, and qacEΔ1, respectively, most of which (81.8%) were multidrug-resistant (MDR). Statistical analysis revealed that the presence of class 1 integron was significantly associated with resistance to streptomycin and tetracycline (p = 0.042). However, there was no association between class 1 integron and other antibiotics used in this study (p > 0.05)., Conclusion: The high frequency of integron class 1 gene in MDR Salmonella strains indicates that these mobile genetic elements are versatile among different Salmonella serotypes, and associated with reduced susceptibility to many antimicrobials., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

In livestock and poultry, broad-spectrum antibiotics such as tetracyclines and fluoroquinolones are widely used; thus, controlling food productions made from these animals is a necessary task. Meat may contain residues of antibiotics, even in low concentrations, which can cause a selection pressure for antibiotic resistance. Therefore, measurement of amounts of antibiotics in meat is of major importance. A total of 41 beef and 41 chicken meat samples were collected for 1 year. Tetracycline and ciprofloxacin were extracted from samples and tested by an indirect competitive enzyme-linked immunosorbent assay. Overall, 100% of the beef and more than 95% of the chicken meat samples were positive for ciprofloxacin. Only one of the chicken meat samples had concentrations of ciprofloxacin higher than maximum residue limit (MRL). For ciprofloxacin, none of the beef meat samples exceeded the MRL. For tetracycline, 75% of the beef and 58% of the chicken meat samples were positive. All of the samples had concentrations of tetracycline lower than MRL. It was revealed that the chicken meat samples had higher levels of both antibiotics than those of beef samples. The amounts of tested antibiotics were not high in the meat samples, consequently using of beef and chicken meat by consumers in Iran is not resulted in entrance of high amounts of the antibiotics into human body.

Objectives: Salmonella enterica serotype Enteritidis is a major serotype associated with human salmonellosis. The main objective of this study was to determine the antibiotic susceptibility patterns and the presence of virulence-associated genes among S. Enteritidis strains isolated from patients with gastroenteritis in Tehran, Iran., Methods: Over a period of 14 months (May 2015 to July 2016), 44 S. Enteritidis isolates recovered from clinical sources were characterised for antimicrobial susceptibility and virulence genes. Possible genetic relatedness among the strains was also assessed using pulsed-field gel electrophoresis (PFGE)., Results: Salmonella Enteritidis isolates showed high rates of resistance to ciprofloxacin (90.9%) and nalidixic acid (77.3%). Of the 44 S. Enteritidis isolates, 30 (68.2%) were resistant to three or more antibiotics. Twenty-two different antimicrobial resistance patterns were detected among the isolates. The most frequent resistance type was antibiotype 14 (resistance to ciprofloxacin, cefuroxime and nalidixic acid), occurring in 8 (18.2%) of the isolates. Notably, all of the isolates carried invA, sefA, sipA and sopE2 virulence genes. Furthermore, 17 virulence profiles were observed among the strains. The most common virulence profile was VP1 (n=17; 38.6%), harbouring all of the virulence genes. Two distinct PFGE patterns were observed among 44S. Enteritidis isolates. There was no association between virulence profiles or antibiotypes and PFGE clusters., Conclusions: Overall, this study provides valuable information on the virulence gene content, antibiotic resistance and genetic diversity of S. Enteritidis isolated from human sources in Iran., (Copyright © 2017 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved.)

Enterobacter asburiae (E. asburiae) is a facultative anaerobic, non-spore-forming gram-negative rod-shaped bacterium belonging to the family of Enterobacteriaceae. It is an opportunistic pathogen that its strains are isolated from a variety of clinical and environmental specimens. Since powdered infant formula milk (PIF) is not a sterile product, it is an excellent medium for bacterial growth. The aim of this study was to isolate and identify E. asburiae from PIF in the neonatal intensive care unit (NICU) and determine antimicrobial susceptibility patterns of this bacterium. A total 125 PIF samples were purchased from drug stores between June 2011 to March 2012. E. asburiae was isolated according to FDA method. For final confirmation, biochemical tests embedded in the API-20E system were used. The drug susceptibility test was performed using the disc diffusion method according to CLSI recommendations. Out of the 125 PIF samples investigated, 2 (1.6%) samples were positive for E. asburiae. All isolated strains were uniformly susceptible to aztreonam, cefotaxim, amikacin, streptomycin, nalidixic acid, meropenem, tetracycline, ceftazidime, and colistin. Variable susceptibility was seen to the some antimicrobial agents tested. Each country should categorize its own designed guidelines for the preparation and handling of PIF adapted to the local environment. Moreover, the pathogenesis of the E. asburiae in infants hospitalized in NICU and other groups such as immunosuppressed patients and HIV infected individuals is uncertain and requires further study.

Four methods for isolation of Yersinia enterocolitica from raw and pasteurized milk from northern Iran were compared. Three hundred and ten raw milk samples were collected from tanks on their arrival at various central dairies, and 40 pasteurized milk samples were collected from tanks on their arrival at a manufacturing plant. Each sample was examined for the presence of Y. enterocolitica by (1) direct culture; (2) enrichment in double-strength buffered peptone water at 4 degrees C for 1 month; (3) enrichment in modified Rappaport medium at room temperature for 72 h after a preenrichment in double-strength peptone water at 4 degrees C for 1 month; and (4) enrichment in a medium containing sucrose, tris (hydroxymethyl) aminomethane, sodium azide, and ampicillin at 28 degrees C for 48 h after a preenrichment in double-strength peptone water at 4 degrees C for 1 month. All samples and enrichments were spread on MacConkey agar plus calcium chloride and Tween 80, Yersinia selective agar, and Hektoen medium plus ampicillin. Five samples (1.6%) of raw milk but no pasteurized milk samples were positive for Y. enterocolitica. No Y. enterocolitica were recovered by methods 1 or 2. Y. enterocolitica were recovered from 2 samples by method 3 followed by culture on Yersinia selective agar, and from 5 samples by method 4 followed by culture on Hektoen medium plus ampicillin. The isolates were biotype 1A or 1B, serotype O:7-13 or O:9 and phage type Xo or Xz. All isolates were resistant to ampicillin and amoxicillin, and sensitive to tetracycline, streptomycin, chloramphenicol, and trimethoprim-sulfamethoxazole.