Antimicrobial Susceptibility Pattern of Staphylococcus aureus with Special Reference to Inducible...

Staphylococcus aureus is a major pathogenic organism responsible for various infections. The emergence of methicillin-resistant S. aureus (MRSA) and inducible clindamycin resistance (ICR) complicates treatment and highlights the importance of accurate detection of Macrolide-Lincosamide-Streptogramin B (MLSB) resistance mechanisms.

This study aimed to assess the antimicrobial susceptibility pattern of S. aureus, detect ICR using the D-zone test, and evaluate its association with MRSA.

A total of 212 nonduplicate S. aureus isolates were obtained from various clinical samples at Medical College Baroda. Identification was performed using standard microbiological techniques. Antimicrobial susceptibility was tested using the Kirby-Bauer disk diffusion method and interpreted as per the Clinical and Laboratory Standards Institute guidelines. MRSA was identified using cefoxitin (30 µg), and ICR was detected via the D-zone test.

Among 212 isolates, 124 (58.49%) were male and 88 (41.51%) were female. MRSA was detected in 40 (18.87%) isolates. ICR (inducible MLSB [iMLSB]) was seen in 48 (22.64%) isolates, MS phenotype in 21 (9.90%) and constitutive MLSB in 9 (4.24%). A significant association was found between MRSA and iMLSB (P < 0.05).

Routine D-zone testing is essential to detect inducible resistance. Continued surveillance and rational antibiotic use are necessary to prevent resistance spread.