Prevalence of methicillin resistant Staphylococcus aureus in Lumbini Medical College and Teaching Hospital, Palpa, Western Nepal.

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.