Abstract
Background. Global concerns have been raised due to upward trend of Vancomycin Intermediate Staphylococcus aureus (VISA) and Vancomycin Resistant Staphylococcus aureus (VRSA) reports which mean casting doubt on the absolute effectiveness of the last line of antibiotic treatment for S. aureus, vancomycin. Hence, epidemiological evaluation can improve global health care policies. Methodology. 171 Isolates of Staphylococcus aureus were collected from different types of clinical samples in selected hospitals in Isfahan, Mashhad, and Tehran, Iran. Then, they were evaluated by agar screening, disk diffusion, and MIC method to determine their resistance to vancomycin and methicillin. The isolated VISA strains were then confirmed with genetic analysis by the evaluation of mecA and vanA genes, SCCmec, agr, and spa type, and also toxin profiles. MLST was also performed. Results and Conclusion. Our data indicated that 67% of isolated S. aureus strains were resistant to methicillin. Furthermore, five isolates (2.9%) had intermediate resistance to vancomycin (VISA). In contrast to usual association of VISA with MRSA strains, we found two isolates of MSSA-VISA. Therefore, our data suggests a probable parallel growing trend of VISA towards MSSA, along with MRSA strains. However, more samples are required to confirm these primarily data. Moreover, genetic analysis of the isolated VISA strains revealed that these strains are endemic Asian clones.
Highlights
Staphylococcus aureus is one of the major causes of hospital and community acquired infections that can vary from mild superficial lesions to acute deep and systemic infections
Thence, for many years vancomycin was the drug of choice for methicillin resistant Staphylococcus aureus (MRSA) infections, until the first S. aureus isolate with reduced sensitivity to vancomycin (vancomycin intermediate Staphylococcus aureus (VISA)) was reported in Japan in 1997 [3]
Of 171 S. aureus isolates analyzed, we found that 115 isolates (67%) were MRSA and 5 isolates (2.9%) showed agr Sccmec pvl hla etc ts1t mecA vanA spa type spa repeat profile
Summary
Staphylococcus aureus is one of the major causes of hospital and community acquired infections that can vary from mild superficial lesions to acute deep and systemic infections. Thence, for many years vancomycin was the drug of choice for MRSA infections, until the first S. aureus isolate with reduced sensitivity to vancomycin (vancomycin intermediate Staphylococcus aureus (VISA)) was reported in Japan in 1997 [3]. Global concerns have been raised due to upward trend of Vancomycin Intermediate Staphylococcus aureus (VISA) and Vancomycin Resistant Staphylococcus aureus (VRSA) reports which mean casting doubt on the absolute effectiveness of the last line of antibiotic treatment for S. aureus, vancomycin. 171 Isolates of Staphylococcus aureus were collected from different types of clinical samples in selected hospitals in Isfahan, Mashhad, and Tehran, Iran. They were evaluated by agar screening, disk diffusion, and MIC method to determine their resistance to vancomycin and methicillin. Genetic analysis of the isolated VISA strains revealed that these strains are endemic Asian clones
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