ABSTRACT
BACKGROUND: Multidrug resistant Staphylococcus aureus is common in both tertiary and primary health care settings. Emergence of methicillin resistance in S. aureus (MRSA) along with macrolide, lincosamide, streptogramin B (MLSB) has made treatment of Staphylococcal infection more challenging. The main objective of this study was to detect MRSA, MLSB (inducible; MLSBi and constitutive; MLSBc) resistant S. aureus using phenotypic methods and to determine their antibiogram. METHODS: Various samples were collected from 1981 patients who attended Lumbini Medical College and Teaching Hospital (LMCTH) during the period of 6 months from September 2015 to February 2016. Out of a total of 1981 samples, 133 S. aureus were isolated. Cefoxitin was used to detect MRSA by the disk diffusion test. Inducible clindamycin resistance (MLSBi) was detected by the D-zone test. The antibiotic profile of all isolates was tested by a modified Kirby Bauer disk diffusion method. RESULTS: Among 133 S. aureus, there were 58 (43.6%) MRSA, 34 (25.6%) MLSBi and 30 (22.6%) MLSBc. Of a total of 64 MLSB, a significant proportion (62.5%) was MRSA (p < 0.001). Among 11 different antibiotics that were tested for S. aureus, MRSA showed significant resistance to 9 (p < 0.05) with the exception of vancomycin and linezolid. All the isolates were 100% sensitive to linezolid. MLSBi organisms were 100% sensitive to vancomycin and linezolid. Both MLSBi and MLSBc showed a higher degree of resistance to multiple antibiotics (p < 0.05). CONCLUSIONS: Isolation of MRSA, MLSBi and MLSBc were remarkably high. Routine use of simple and cost effective methods such as the disk diffusion test by cefoxitin for MRSA and the D-zone test for MLSBi organisms can easily identify these isolates. Antibiotic resistance profiles from this study can optimize the treatment of multi-drug resistant S. aureus.
