Antibiotic susceptibility pattern among Staphylococcus spp. with emphasis on detection of mecA gene in methicillin resistant Staphylococcus aureus isolates

Staphylococcus aureus is a major pathogen in hospital setting and in the community and causes a wide range of diseases. MRSA infection has recently become a serious problem in anti-microbial chemotherapy. The aim of the study was to detect and analyze the antibiotic diversity and isolation of methicillin resistance gene [mecA] of S. aureus isolated from Tehran hospitals as a rapid and reliable method. We studied 585 isolates of staphylococcus spp. recovered from patients at 3 clinical centers in Tehran from October 2005 to October 2006. antibiotic susceptibility test of isolates was achieved with 13 antibiotics by disc diffusion. The MIC of methicillin was also performed by broth micro dilution assay. PCR was used for detection of mecA gene. Totally, 321 [54.7%] isolates were identified as S. aureus. 66, 65, 88, 88, 100, 41, 38, 41, 0, 40, 93, 20 and 64% of S. aureus isolates were resistant to kanamycin, cephotaxim, methicillin, oxacillin, ampicillin, erythromycin, clindamycin, sulphamethoxazole-trimethoprime, vancomycin, chloramphenicol, ciprofloxacin, gentamicin and tetracycline, respectively. All MRSA and 63% of intermediate isolates carried mecA gene. In contrary to other studies in Iran, the prevalence of methicillin resistance is rising up in Tehran and most of MRSA isolates were resistance to 5 antibiotics at least. Vancomycin, chloramphenicol, gentamicin and clindamycin are the most effective antibiotics. All MRSA isolates had mecA gene with different expression. Detection of mecA gene is a rapid and reliable method for identification of MRSA isolates

Distribution of enterococcal species and detection of vancomycin resistance genes by multiplex PCR in Tehran sewage

Enterococci are important because of their role as the leading cause of nosocomial infections which have a significant role in the dissemination and persistence of antimicrobial resistance genes. In this study, we determined the distribution of enterococcal species in the sewage treatment plants in Iran. Furthermore, we improved a rapid and specific PCR method using primers [sodA and ddl genes] for identification of enterococci spp.: A total number of 712 enterococci spp. Were isolated and the results showed that 56%, 24%, 12%, 4%, 2%, 1% and 1% isolates were E. faecium, E. hirae, E. faecalis, E. gallinarum, E. casseliflavus, E. mundtii and other enterococcal spp., respectively. The use of species-specific PCR was in agreement with the biochemical tests. Furthermore, multiplex PCR was developed to study the presence of vancomycin resistant genes in E. faecium or E. faecalis. The multiplex PCR appeared to be a useful, rapid and specific method for detecting and discriminating genotypes for vancomycin-resistant Enterococcus