The Survey on Prevalence and Risk Factors for Antibiotic-Resistant Staphylococcus Aureus Isolated from Samples in Kashan Hospitals Moniri R1, Shafiee M2 1 Dept of Microbiology and Immunology, Kashan University of Medical Sciences, Kashan, Iran 2 Pasteur Institute of Iran, Tehran, Iran Corresponding Author's Address: Dept of Microbiology and Immunology, Kashan University of Medical Sciences, Kashan, Iran E-mail: moniri@kaums.ac.ir Received: 20 July, 2008 Accepted: 17 Nov, 2008 Background and Objective: Methicillin-resistant Staphylococcus Aureus (MRSA) is a serious problem in hospitals. The purpose of this study was to determine the prevalence and related risk factors of methicillin resistance S. aureus isolated from clinical specimens in Kashan hospitals. Materials and Methods: This descriptive study was carried out on 100 S.aureus strains isolated from patients admitted to Kashan hospitals in 2006- 2007. Strains were inoculated on blood agar containing 5% sheep blood and 7.5% mannitol salt agar media, and were incubated at 35°C for 24 hours. The isolated S. aureus strains were identified using gram staining, catalase test, coagulase tube test, growth on chrome agar and the DNAse test. The antibiotic sensitivity test was determined by disk diffusion method. Variables including age, sex, previous hospitalization, duration of hospitalization, previous antibiotic therapy, and type of the disease, were recorded in questionarres. Data were analyzed statistically by the Chi-square and Fischer’s exact tests. Results: Penicillin and Ciprofloxacin revealed the highest and lowest resistance rates respectively (99%, vs 11 %). Meticillin resistance was 22% and an intermediate resistance to Vancomycin was detected in 7% of isolates. A significant correlation was established among the presence of resistant staphylococci with age of more than 46 years old (P<0.040), previous hospitalization (P<0.000), hospitalization for more than 1 week (P<0.000), previous antibiotic therapy (P<0.004), and administration of antibiotics for more than 1 week (P<0.002). Conclusion: Awareness about the prevalence of antibiotic resistant S.aureus and identification of risk factors for infection with resistant isolates is essential to help clinicians, choosing appropriate antibiotic regimen.

Background and Objective: Methicillin resistant Staphylococcus aureus (MRSA), which is the most common cause of nosocomial infection, has been a major cause of morbidity and mortality around the world. This study was carried out to find out the resistance pattern and staphylococcal cassette chromosome mec (SCCmec) typing among MRSA.
Materials and Methods: This descriptive work was done on 87 Methicillin resistant Staphylococcus aureus isolates which were collected from the patients with infections in a teaching hospital in Kashan, Iran, during the period of 2009. The isolates were tested for antibiotic resistance by the disc-diffusion method, covering 10 antimicrobials. The genotypes of SCCmec subtypes were determined by multiplex PCR.
Results: Amomg 87 MRSA isolated tested; the highest resistance was shown against erythromycin, clindamycin, sulfamethoxazole-trimethoprim, and tetracycline respectively. By contrast, the highest sensitivity was shown to amikacin. All of the isolates were resistant to Beta-lactams. All of the isolates were resistant to at least three classes of antibiotics, and all of the isolates were sensitive to vancomycin.
Three (3.4%) MRSA strains were SCCmec type I, 12 (13.8%) were type II, 8 (9.2%) were type IV-b, 4 (4.6%) were type IV-d, and 3 (3.4%) were typeV. Overall, 57 (65.5%) MRSA strains could not be typed. Conclusion: The rising trend of multi-resistance to antibiotics poses an alarming threat to treatment of MRSA infections. Our findings show that clinical isolates of MRSA in our hospital carrying various kinds of staphylococcal cassette chromosome mec (SCCmec) types. SCCmec typse II and IV were the predominant strain of MRSA identified.

Background and Objective: Pseudomonas aeruginosa is the most common pathogen causing nosocomial infections. The aim of this study was to determine the antimicrobial susceptibility pattern and prevalence of ESBLs in clinical and environmental isolates of P. aeruginosa by phenotypic and genotypic techniques. Materials and Methods: In this descriptive study, a total of 100 P. aeruginosa strains isolated from different clinical and environmental specimens were used. The antibiotic resistance pattern to eight antimicrobial agents was determined by disk diffusion method. The ESBLs producing strains were confirmed by double-disk-diffusion test, and the blaTEM-1, blaSHV-1, blaSHV-5, blaCTX-M-1, blaCTX-M-2, blaCTX-M-3, blaCTX-M-9, blaOXA-1, blaGES-1, and blaGES-2 genes were detected by PCR. Results: Piperacillin and ciprofloxacin showed the highest (36%) and the lowest (16%) resistance against the isolates, respectively. Thirty percent of the total isolates were resistant to at least three classes of antibiotics. By double-disk-diffusion test, eight strains (8%) were ESBL positive. According to the PCR results, the blaGES-2, blaSHV-1, blaSHV-5, and blaCTX-M-1 genes were detected in 8, 2, 2, and 1 isolates of ESBLs producing strains respectively. Conclusion: The blaGES-2 gene displayed an expanded hydrolysis profile to the antibiotic imipenem. In fact, this enzyme, which plays an important role in resistance to imipenem, was detected in all ESBLs producing P. aeruginosa strains. This is the first report describing blaGES-2 producing P. aeruginosa in Iran.