Study of Hospital Acquired Methicillin-Resistant Staphylococcus aureus in a Tertiary Care Hospital of Bihar

Objective: There has been a steady increase in the prevalence of Methicillin-Resistant Staphylococcus Aureus (MRSA) infections throughout the world, especially in hospital settings, and is exacerbated by its ability to cause cross infections, colonization, and resistance to multiple classes of commonly used antimicrobials. There are various risk factors associated with MRSA infections among hospitalized patients. Studies which focus on current antimicrobial susceptibility pattern and risk factors associated with such important pathogen are scanty for this region and will be of great importance in the prevention and proper antimicrobial therapy for such infections. Methods: Patients admitted to various departments of Indira Gandhi Institute of Medical Sciences, Patna in the duration of February 2014 to November 2015 were included in the study. Staphylococcus aureus and further MRSA were identified using the standard method according to CLSI 2014 guidelines. Isolates screened as MRSA were further tested for identification and antimicrobial susceptibility testing using VITEK-2 Compact (biomerieux, USA). Hospital-acquired MRSA and Methicillin Sensitive Staphylococcus Aureus (MSSA) infections were analyzed for associated risk factors by collecting their data for various laboratory and clinical parameters. Chi-square test was used for comparison between various categorical variables between patients with hospital-acquired MSSA and MRSA infections where p ≤ 0.05 were considered statistically significant. Results: Out of the 102 Staphylococcus aureus isolates, 27 (26.5%) were identified as MRSA strains and 75 (73.5%) were MSSA strains. Most of the MRSA isolates (66.7%) and MSSA isolates (62.7%) were isolated from patients below 40 years of age. There is a male predominance in both MRSA (M:F=1.1:1) and MSSA (M:F=1.3:1) isolates. Orthopedics and Surgery departments contributed to the majority of MRSA isolates (48.15%) while Medicine and Orthopedics contribute to most of the MSSA isolates (37.3%). Both the MRSA and MSSA strains were mostly isolated from pus (38.2%) and blood samples (23.5%). Vancomycin and Linezolid showed the best sensitivity against MRSA strains. Both the MRSA and MSSA strains were highly resistant to ampicillin and penicillin. Antibiotics like erythromycin, clindamycin, and gentamicin showed statistically significant (p ≤ 0.05) differences in resistance among MRSA and MSSA strains. Several risk factors like length of stay in hospital or ICUs, burn injury, severe trauma, catheterization, use of mechanical ventilators, etc. were found to be statistically significant (p ≤ 0.05) for MRSA infections. Conclusion: MRSA, with its high prevalence, continues to be an important pathogen regarding healthcare-associated infections. This organism is also multidrug-resistant and selecting proper antimicrobials for empirical therapy should be based on the current antibiogram obtained in the region.