A Comparative Analysis of Community Acquired and Hospital Acquired Methicillin Resistant Staphylococcus Aureus

Abstract

Staphylococcus aureus has developed resistance against most of the therapeutic agents. The most notable example of this phenomenon was the emergence of Methicillin resistant Staphylococcus aureus (MRSA). We are reporting the prevalence and the antibiotic susceptibility pattern of the MRSA isolates from a tertiary care hospital. A total of 450 Staphylococcus aureus isolates from clinical samples were taken up for the study and they were screened for MRSA by using standard microbiological methods. An antibiotic assay was done for the confirmed MRSA isolates. The differentiation of the isolates into community acquired MRSA (CAMRSA) and hospital acquired MRSA (HAMRSA) was done according to the prescribed criteria. The double disc diffusion test was performed for both the groups, to identify the inducible clindamycin resistance. The HAMRSA and the CAMRSA isolates were subjected to a molecular analysis by PCR, to detect the presence of the Mec A gene and the PVL gene respectively. Out of the 450 Staphylococcus aureus isolates, 121 were Methicillin Resistant Staphylococcus aureus (MRSA, 27%) and 329 were Methicillin Sensitive Staphylococcus aureus (MSSA, 73%). 91 MRSA isolates were grouped into HAMRSA and 30 were grouped into CAMRSA, with a prevalence of 20% and 7% respectively. All the MRSA strains were resistant to Penicillin (100%), Cefoxitin (100%) and Oxacillin (100%). 53.7% of the HAMRSA isolates showed inducible clindamycin resistance against that of 44.4% among the CAMRSA isolates. All the isolates were susceptible to Vancomycin and Linezolid. 64% of the HAMRSA isolates showed the presence of the Mec A gene and 48% of the CAMRSA isolates showed the presence of the PVL genes. The prevalence of the HAMRSA was higher than that of the CAMRSA and they showed a higher drug resistance.