Occurrence of methicillin-resistant Staphylococcus aureus among clinical samples in Tehran and its correlation with the site of infection

Abstract number: P1883

Hiradfar S., Azimian A., Najar Peerayeh S., Naderi M., Farshchian M., Salehipoor Z.

Introduction and Objectives: Methicillin-resistant Staphylococcus aureus (MRSA) is responsible for an increasing number of serious nosocomial and community acquired infections including superficial lesions and wound infections, osteomyelitis, endocardiris, pneumonia, bacteraemia, Toxic shock syndrome and food poisoning. The purpose of this study was to define the prevalence of of MRSA strains among S. aureus strains isolated from selected Tehran hospitals with conventional and molecular methods.

Material and Methods: A total 235 isolates were evaluated by disk diffusion and MIC agar dilution tests according to the guidelines of the National Committee for Clinical Laboratory Standards (NCCLS) and PCR assay for mecA gene.

Results: from 2006 to 2007 a total of 235 strains from patients and healthy persons (163(%69) men and 72(%31) women) were evaluated. Our strains isolated from blood, urine, coetaneous samples, respiratory tract samples, nasal swaps and miscellaneous samples. Prevalence of MRSA strains in different samples is shown in table 1.

Conclusion: our results show good correlation between phenotypic and genotypic methods for antibiotic susceptibility tests. Highest percent of MRSA strains isolated from respiratory tract samples (%49), followed by Blood(%48), other samples (for example Tissues or Exudates or Bone marrow) (%45), Urine (%43), Coetaneous samples (%41) and finally Nasal swabs (%34). These differences were not statistically significant (P > 0.05).

Table 1. Resistance against oxacillin in different specimens with various phenotypic and genotypic tests

 MIC*Disk diffusionmecA gene positive
Blood (n = 60)29 (48%)30 (50%)30 (50%)
Urine (n = 3716 (43%)16 (43%)17 (46%)
Cutaneous sample (n = 43)18 (42%)18 (42%)19 (44%)
Respiratory tract (n = 55)27 (49%)27 (49%)28 (51%)
Other (n = 9)4 (45%)5 (46%)5 (46%)
Nasal swab (n = 31)11 (35%)12 (39%)11 (35%)
*According to NCCLS guidelines isolates with MIC geqslant R: gt-or-equal, slanted 4 mg are resistant to oxacillin.

Session Details

Date: 16/05/2009
Time: 00:00-00:00
Session name: 19th European Congress of Clinical Microbiology and Infectious Diseases
Location: Helsinki, Finland, 16 - 19 May 2009
Presentation type:
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