Molecular epidemiology of methicillin resistant staphylococcus aureus colonizing the anterior Nares of school children of Udupi Taluk

Constellation of methicillin-resistant genomic islands (SCCmec) among nasal meticillin-resistant Staphylococcus aureus isolates

The apprehensiveness for the knowledge vacuum on existential threat of nasal carriage of pvl+ healthcare-acquired meticillin-resistant Staphylococcus aureus (HA-MRSA) strains amongst subjects in hospitals have led us to pursue a grasp on the constellation of staphylococcal cassette chromosome mec (SCCmec) types and pvl gene among mecA positive MRSA nasal strains. This was accomplished by phenotypic (catalase, coagulase, Microgen staph ID, ORSAB) and genotypic (polymerase chain reaction) biotyping techniques. All the mecA+ strains harboured the SCCmec gene; SCCmec type I prevailed in 43.75% and pvl was found in 42.1% of the isolates. Dual carriage of mecA and pvl genes occurred in six (37.5%, n = 6/16) strains. Overall, majority of the mecA+ MRSA strains documented in this study carried SCCmec elements of the HA genotype with a hint of community-acquired (CA)genotype suggesting a possible coexistence of both HA-MRSA and community-acquiredhealthcare-acquired meticillin-resistant Staphylococcus aureus (CA-MRSA) strains. Consequently, the implementation of methodical surveillance is needed for the evaluation of potential shifts in directionality of (HA-MRSA/CA-MRSA) pvl+ MRSA clones in our hospitals for effective and prudent antimicrobial stewardship.

Prevalence of MRSA Nasal Carriage in Patients Admitted to a Tertiary Care Hospital in Southern India

INTRODUCTION

Infections with MRSA, both community and hospital acquired, are well established and the source of infection is often a carrier. There are very few studies showing the magnitude of MRSA nasal colonization among healthy persons from the community. This study was conducted to detect the prevalence of MRSA nasal carriage in patients who did not have any known risk factors associated with HA- MRSA colonization, admitted to a tertiary care centre in Kerala.

MATERIALS AND METHODS

Nasal swabs were collected from patients within 24 hours of admission. Specimen were inoculated on chromogenic agar (HiCrome MeReSa agar-HiMedia) for MRSA screening. Isolates were then subjected to antibiotic sensitivity tests, SCCmec typing and PVL gene detection.

RESULTS

Out of 683 patients, 16 carried MRSA in their nares (2.3%). Of the 16 strains 13 (81.25 %) strain were SCCmec type III and one belonged to SCCmec type IV (6.25 %). Two strains failed to amplify SCCmec genes. Three strains carried genes for PVL toxin (18.75%).

CONCLUSION

With a better understanding of the complex epidemiology of MRSA it is increasingly apparent that demarcations between the HA and CA phenotypes are not as clear cut as previously thought. In this study of nasal carriage of MRSA in the community we have demonstrated prevalence consistent with published data. Most isolates however were shown to belong to the type conventionally assigned to HA-MRSA.

Typing of Methicillin Resistant Staphylococcus Aureus Using DNA Fingerprints by Pulsed-field Gel Electrophoresis

Background:

Methicillin resistant Staphylococcus aureus (MRSA) is responsible for a wide spectrum of nosocomial and community associated infections worldwide. The aim of this study was to analyze MRSA strains from the general population in Canton Sarajevo, B&H.

Methods:

Our investigation including either phenotypic and genotypic markers such as antimicrobial resistance, pulsed-field gel electrophoresis (PFGE), SCC typing, and Panton-Valentine leukocidin (PVL) detection.

Results:

Antimicrobial susceptibility: all MRSA isolates were resistant to the β-lactam antibiotics tested, and all isolates were susceptible trimethoprim sulphamethoxazole, rifampicin, fusidic acid, linezolid and vancomycin. Sixty-eight per cent of the MRSA isolates were resistant to erythromycin, 5% to clindamycin, 5% to gentamicin and 4% to ciprofloxacin. After the PFGE analysis, the isolates were grouped into five similarity groups: A-E. The largest number of isolates belonged to one of two groups: C: 60 (60%) and D: 27 (27%). In both groups C and D, SCCmec type IV was predominant (60% and 88, 8%, respectively). A total of 24% of the isolates had positive expression of PVL genes, while 76% showed a statistically significantly greater negative expression of PVL genes.

Conclusion:

SCCmec type IV, together with the susceptibility profile and PFGE grouping, is considered to be typical of CA-MRSA