Comparison of Community - associated methicillin resistant staphylococcus aureus (CA-MRSA) and healthcare - associated MRSA (HA-MRSA) infections in Mangalore, South India

Community-associated methicillin resistant Staphylococcus aureus (CA-MRSA) and healthcare-associated MRSA (HA-MRSA) cause different kinds of infections. HA-MRSA exhibit higher degree of antibiotic resistance compared to CA-MRSA. The objectives of the present study were to compare the antibiotic resistance and infections caused by CA-MRSA and HA-MRSA. A cross-sectional study was carried out at tertiary care hospitals. Infections were identified as community or healthcare-associated based on CDC definition. Standard conventional methods were used for the isolation and identification of S.aureus. Methicillin resistance was identified by the cefoxitin (30μg) disk diffusion method. Antibiotic susceptibility was done using Kirby - Bauer disk diffusion method. Inducible clindamycin resistance was detected by D-test. Statistical analysis was done using chi square test. A total of 103 CA-MRSA and 107 HA-MRSA were studied. CA-MRSA was significantly more in skin and soft tissue infections (SSTI). HA-MRSA showed significantly higher (P< 0.05) resistance to ciprofloxacin, clindamycin, co-trimoxazole, erythromycin and gentamicin, and multidrug resistance. Constitutive clindamycin resistance was significantly higher (P< 0.05) in HA-MRSA compared to CA-MRSA. CA-MRSA and HA-MRSA are associated with SSTI and bacteremia respectively with a varying degree of antibiotic resistance. Treatment of infection caused by CA and HA-MRSA continues to be difficult especially in the presence of inducible clindamycin resistance. Routine antibiotic resistance results should always be accompanied with results of D-test for preventing therapeutic failure. Proper selection of this antibiotic is needed for preventing therapeutic failure and emergence of constitutive clindamycin resistance.