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Objective: To assess vancomycin MIC creep phenomenon in methicillin-resistant Staphylococcus aureus isolated from clinical specimens. Methods: This descriptive study was conducted in Microbiology department of University of Health Sciences, Lahore from January 2016- December 2019. In this study, vancomycin MICs were revealed by E test method for clinical MRSA strains. For the final evaluation, a single isolate from each patient was taken. The reported vancomycin MICs results were used and the values were not rounded up to the next upward value. For every study year, MIC50, MIC90, median and geometrical mean MIC, percentages of susceptible and resistant strains were calculated. Results: A total of 352 MRSA strains were isolated out of 2704 staphylococcal isolates. Our study showed elevated vancomycin MIC among MRSA isolates. The majority of isolates showed MIC values =1.5µg/ml. MIC50, MIC 90 was constant throughout four years period. However, geometric mean MIC increased gradually during the study period. The MIC greater than base year median was overall 17.3%. A complete shift can be observed between MIC "1.0" and "2.0" the percent of cases with MIC "1.0" decreased and with MIC "2.0" increased over time crossing each other in 2017. Conclusion: Vancomycin MIC creep was identified in clinical isolates of MRSA, during four years of study period. Even though there is an absence of VISA and VRSA strains; this significant increase in vancomycin MIC trend is indeed worrying for the clinicians about the threat of potential failure of treatment in MRSA infections. [ABSTRACT FROM AUTHOR]

Background and Objectives: Methicillin-resistant S. aureus (MRSA) tends to be resistant to multiple antibiotics. Methicillin resistance is conferred by the acquisition of the mecA gene, which is carried by a mobile genetic element called the staphylococcal cassette chromosome mec (SCCmec). There are five major types of SCCmec elements (I-V). The majority of hospital-acquired MRSA (HA-MRSA) strains carry SCCmec types I, II, or III, whereas community-acquired MRSA (CA-MRSA) strains carry SCCmec types IV or V. In addition, Panton-Valentine Leucocidin (PVL) is a gene encoding a powerful cytotoxin that is strongly associated with CA-MRSA strains. The present study was aimed to identify the types of SCCmec and PVL genes among clinical MRSA isolates. Methods: This study was conducted in 5 tertiary care hospitals in Makkah city from March to September of 2012. A total of 206 S. aureus clinical isolates were analysed using standard microbiological methods. Multiplex PCR was performed on genomic DNA from MRSA isolates in order to identify the types of SCCmec. In addition, PCR was performed to detect the PVL gene among the isolates. Results: Of the 206 S. aureus isolates, 114 (55.3%) were MRSA, and 100 of the MRSA isolates carried the mecA gene. Results from SCCmec typing revealed that 3% were type I; 9% were type II; 47% were type III, and 29% were type IV. Nineteen per cent of the isolates harboured the PVL gene. Furthermore, there was a statistically significant correlation between the presence of the PVL gene and SCCmec type IV. Conclusion: The virulence of MRSA strains is increasing in both hospital and community settings in Makkah, highlighting the importance of their rapid identification in order to appropriately control infection. [ABSTRACT FROM AUTHOR]