Background-The cag pathogenicity island (PAI), which can divide into two parts: cagI and cagII, is the most well-known virulence factor of Helicobacter pylori.

Staphylococcus aureus is considered one of the most important food borne pathogens. A total of 111 isolates of S. aureus were cultured from raw milk samples during January 2009 to June 2009 from Tehran and Mashhad. The coagulase gene polymorphism and the prevalence of classical enterotoxin genes of S. aureus strains were determined by PCR-RFLP (restriction fragment length polymorphism) and Multiplex-PCR. Disk diffusion method was used to determine the susceptibility of isolates to antimicrobial agents as instructed by Clinical and Laboratory Standards Institute. Sixty-seven % of the isolates harboured one or more enterotoxin genes. The most prevalent gene was sec, found in 59 % of the isolates. Approximately 8% of the isolates were positive for sea, seb and sed genes. Only one isolate had see gene. The rate of coexistence of enterotoxin genes was 14%. All S. aureus isolates were susceptible to ciprofloxacin, gentamicin, imipenem, minocycline, oxacillin and vancomycin. They were resistant to ampicillin (64%), penicillin (56%), clindamycin (22%), tetracycline (22%), doxycycline (19%), teicoplanin (13%), rifampin (2%) and trimethoprim-sulfamethoxazole (2%). On the basis of coagulase gene analysis of 111 S. aureus isolates, the PCR products of 56 isolates were digested with Alu I that produced three distinct patterns. These data indicate the high prevalence of enterotoxigenic S. aureus in raw bovine milk in Tehran and Mashhad, and highlight the importance of proper quality control of dairy products for public health.

The geographical variation in Helicobacter pylori genotypes is an observed phenomenon. Cytotoxin associated genes A (cagA) and E (cagE), and vacuolating cytotoxin (vacA) genotypes of H. pylori are associated with peptic ulcer disease (PUD). This study compared the distribution of these genotypes in Iranian and Afghani isolates and their association with clinical outcomes. H. pylori infected patients, as proven by positive culture, were recruited prospectively. A total of 70 patients, 55 Iranian (26 men and 29 women, mean age 48 +/- 18 years) and 15 Afghani immigrants (13 men and 2 women, mean age 34.8 +/- 11 years) living in Tehran, Iran were enrolled in this study. DNA was extracted from isolated H. pylori and polymerase chain reaction was carried out to determine the cagA and cagE status and vacA alleles. The number of gastric cancer, peptic ulcer and gastritis cases was 11, 23 and 36, respectively. The cagA positive isolates were more common in Iranian (67%) than Afghani isolates (60%). cagE was positive in 53% of Afghani compared to 51% of Iranian isolates. The most common vacA s-region genotype was s1; 80% in Afghani and 67% in Iranian. The slml was a frequently observed genotype in Afghani strains (53%) while s1m2 (47%) was more common in strains isolated from Iranian patients. There is a difference in the H. pylori strains between Iranian and Afghani groups, for instance Iranian isolates were similar to European isolates while Afghani isolates were similar to isolates from India. However, there was no significant association between cagA, cagE and vacA genotypes and clinical outcomes in Iranian and Afghani patients.

The incidence of the virulence-associated genes cdtA, cdtB, cdtC, cadF, dnaJ, racR, and pldA has been investigated in Campylobacter jejuni and Campylobacter coli collected from raw chicken and beef from retailers in Tehran, Iran, and from hospitalized children (age, ≤14 years) suffering from diarrhea. Campylobacter spp. were collectively identified by morphological and biochemical methods. Campylobacter jejuni and C. coli were discriminated from other Campylobacter spp. by amplification of a specific conserved fragment of the 16S rRNA gene. The distinction between C. jejuni and C. coli was subsequently made by molecular determination of the presence of the hipO gene in C. jejuni or the ask gene in C. coli. Fragments of the studied virulence-associated genes, cdtA, cdtB, cdtC, cadF, racR, dnaJ, and pldA, were amplified by PCR and subjected to horizontal gel electrophoresis. A total of 71 isolates of C. jejuni and 24 isolates of C. coli from meat were analyzed, while the numbers of isolates from the hospitalized children were 28 and 9, respectively. The unequal distribution of C. jejuni and C. coli in the samples has also been reported in other studies. Statistical analyses by the use of the two-tailed Fisher's exact test of the occurrence of the virulence genes in the isolates of different origins showed that the occurrence of the dnaJ gene was consistently significantly higher in all C. jejuni isolates than in C. coli. The occurrence of the other virulence markers did not differ significantly between species in the majority of the isolates. The PCR results also showed that the occurrence of the virulence markers in the analyzed isolates was much lower than in other studies, which may be caused by a divergent genomic pool of our isolates in comparison with others.