Colonization and Genetic Diversity of MRSA Among ICU Patients and Healthcare Workers From a Hospital of Northeastern India

Abstract

Background: The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) is diverse in different geographic regions, and transmission of MRSA in hospital settings occurs either through the patients or asymptomatic healthcare workers who MRSA colonized in the nares and thus act as a potential reservoir of infection for susceptible patients. Methods:S. aureus isolates were collected from ICU patients and healthcare workers at Gauhati Medical College and Hospital, Assam, India, from May 2010 to April 2015. Premoistened swab samples were obtained from the ICU patients from 4 different sites (ie, nares, axilla, groin, and perianal region) within 48 hours of admission. For healthcare workers (HCWs) a nasal swab was obtained. The isolates were identified by phenotypic and genotypic methods using CLSI guidelines and PCR (fem B, MecA, and PVL). The antibiograms were obtained using a Vitek 2 system. Results: For 84 patients admitted to the ICU, swab samples were obtained from various sites, and S. aureus was observed in 34 samples (40.5%). Among the isolates, 13 (38%) were MRSA and 21 (62%) were methicillin-susceptible Staphylococcus aureus (MSSA). Among the HCWs from the ICU, growth of S. aureus was obtained in 10 of 30 samples (33.34%), of which 3 (30%) were MRSA and 7 (70%) were MSSA. S. aureus isolates were genotypically identified as fem B among colonized patients (40.5%) and HCWs (33.34%). MRSA (mecA positive) was detected in 3% of colonized patients and 30% of HCWs. Among the ICU patients, 78.56% were PVL-positive S. aureus: 21.42% were PVL-positive MRSA and 57.14% were PVL-positive MSSA. Multilocus sequence typing of the 7 housekeeping genes against 2 S. aureus isolates showed the presence of ST1428, which had not been reported in India, whereas the other sequence was entirely novel. The MDR rates were 68% and 75% among ICU patients and HCWs, respectively, and all the strains were mupirocin sensitive. The S. aureus isolates were significantly proportional among HCWs compared to the colonized group (P = .031). Conclusions: The study results show a high prevalence of PVL-positive MSSA and MRSA among ICU patients. This finding indicates its transmission among hospitalized patients through the HCWs, for which constant monitoring of the pathogen, particularly its phenotypic and genotypic variations and antimicrobial resistance pattern, is needed to develop effective strategies for infection prevention.

Funding: None

Disclosures: None