Genetic characterization of two vancomycin-resistant Staphylococcus aureus isolates in Kerman, Iran

摘要

Aim: The aim of this study was the genetic characterization of two clinical vancomycin-resistant Staphylococcus aureus (VRSA) isolates. Materials and methods: Resistance to vancomycin was determined by phenotypic method. PCR was used for detection of mecA, vanA, ermA, ermB, ermC, msrA/B, aph (2”)-Ic, aph (3?)-IIIa, pvl , Immune Evasion Cluster [ sea, sep, chip, sak and scn ] genes and biofilm operon ica ABCD. On the other hand, multilocus sequence typing and agr typing methods were performed for the determination of clonal relationship and van operon was detected and sequenced. Results: Vancomycin-resistant Staphylococcus aureus strain 1 (VRSA-1) was positive for vanA, ermA, ermC, aph (2”)-Ic, aph (3?)-IIIa, sea, sep, ica D genes, belonging to agr type I; SCC mec type III; spa type t030; and ST239. However, the genetic characterization of Vancomycin-resistant Staphylococcus aureus strain 2 (VRSA-2) revealed the presence of various types of resistance genes vanA, ermA, ermC, aph (2”)-Ic, aph (3?)-IIIa, sea , i caD , relating to agr type I; SCC mec type III; spa type t459; and ST239. The presence of transposon Tn 1546 was determined by PCR sequencing.The Basic Local Alignment Search Tool analysis of van operon in the VRSA isolates showed 99.6% sequence homology to Tn 1546 in vancomycin-resistant enterococci, indicating the vanA operon has an enterococcal origin. Conclusion: In conclusion, the ST239 is one of the most common clones of MRSA isolates which involved the hospital-associated infections, therefore, the emergence of VRSA isolates with ST239 increased the spread of resistance to vancomycin in the hospital settings.