Emergence of Vancomycin Resistant Staphylococcus Aureus Isolated from Patients in ICUs of Zagazig University Hospitals

Abstract

Background : Staphylococcus aureus infections treatment has become more complicated with emergence of a methicillin-resistant Staphylococcus aureus (MRSA) strain. Vancomycin has become the drug of choice for the treatment of serious MRSA infections Since the 1980s, however its efficacy is now being doubted due to the emergence of vancomycin resistant staph aureus (VRSA) that are always methicillin-resistant. Objectives: to investigate the emergence of vancomycin resistant Staphylococcus aureus among Staphylococcus aureus isolates from patients admitted to our hospital ICUs, and to determine the sensitivity of these isolates to different antimicrobial agents also to investigate for the presence of vanA gen in VRSA. Methodology: a total of 114 Staphylococcus aureus isolates were recovered from different clinical samples of patients admitted to ICUs over two years. All isolates were identified by Matrix-assisted laser desorption ionization–time of flight mass spectrometry and its antimicrobial susceptibility was investigated by VITEK 2 instrument, MRSA were identified, vancomycin MIC was confirmed by E test, mecA and vanA genes were investigated by PCR technique. Results: among Staphylococcus aureus isolates, there were 90/114 (78.9%) diagnosed as MRSA, the most active antimicrobial agent against these MRSA isolates was tigacyclin (100%) followed by linezolid (87.8%). we detected the emergence of VRSA that were 8.8% (10/114), all VRSA isolates were previously diagnosed as MRSA, percentage of VRSA among MRSA was 11% . The results of PCR showed that there were 88/90 MRSA isolates carrying mecA gene and all VRSA (10isolates) were positive for vanA and mecA genes. Conclusion: The results of this study can be considered as an advance warning about the emergence and dissemination of VRSA strains in our region.