Inducible and constitutive clindamycin resistance in Staphylococcus aureus in a northeastern Indian tertiary care hospital

  • Amit Banik North Eastern Indira Gandhi Regional Institute of Health and Medical Sciences, Shillong, India
  • Annie Bakorlin Khyriem North Eastern Indira Gandhi Regional Institute of Health and Medical Sciences, Shillong, India
  • Jeetendra Gurung North Eastern Indira Gandhi Regional Institute of Health and Medical Sciences, Shillong, India
  • Valarie Wihiwot Lyngdoh North Eastern Indira Gandhi Regional Institute of Health and Medical Sciences, Shillong, India
Keywords: D-test, inducible clindamycin resistance, erythromycin, MRSA, Staphylococcus aureus

Abstract

Introduction: Staphylococcus aureus is one of the most common pyogenic bacteria. They are notorious for developing prompt resistance to newer antimicrobials. With increasing incidence of methicillin-resistant S. aureus (MRSA) isolates, the treatment options are also becoming limited. Clindamycin is an excellent drug for skin and soft tissue infections, but resistance mediated by the inducible phenotype (iMLSB) leads to in vivo therapeutic failure even though there may be in vitro susceptibility. The double disk approximation test (D-test) can reliably detect the presence of such isolates. This study was aimed to detect and report the prevalence of the iMLSB phenotype in NEIGRIHMS, a tertiary care center in Northeast India.

Methodology: A total of 243 consecutive isolates were subjected to routine identification tests followed by antimicrobial sensitivity testing. Erythromycin-resistant isolates were tested for inducible resistance phenotype by the D-test.

Results: Among strains tested, 95 (39%) were erythromycin resistant. Twenty-six (10.7%) isolates were D-test positive (iMLSB phenotype), 41 (16.88%) were constitutively resistant (cMLSB phenotype), and 28 isolates (11.52%) were found to be negative by D-test. The incidence of both inducible and constitutive phenotypes was higher in MRSA isolates compared to methicillin-sensitive S. aureus (MSSA) isolates.

Conclusions: This study revealed a moderate prevalence of the inducible clindamycin phenotype in the staphylococcal isolates tested. Clinical microbiology laboratories in areas of high MRSA prevalence should consider performing the D-test routinely. This will help prevent prescription of drug(s) whose therapeutic efficacy is doubtful.

Author Biographies

Amit Banik, North Eastern Indira Gandhi Regional Institute of Health and Medical Sciences, Shillong, India

Senior Resident Doctor

Department of Microbiology

NEIGRIHMS

Annie Bakorlin Khyriem, North Eastern Indira Gandhi Regional Institute of Health and Medical Sciences, Shillong, India

Associate Professor

Department of Microbiology

NEIGRIHMS

Jeetendra Gurung, North Eastern Indira Gandhi Regional Institute of Health and Medical Sciences, Shillong, India

Senior Resident Doctor

Department of Microbiology

NEIGRIHMS

Valarie Wihiwot Lyngdoh, North Eastern Indira Gandhi Regional Institute of Health and Medical Sciences, Shillong, India

Associate Professor

Department of Microbiology

NEIGRIHMS

Published
2015-07-30
How to Cite
1.
Banik A, Khyriem AB, Gurung J, Lyngdoh VW (2015) Inducible and constitutive clindamycin resistance in Staphylococcus aureus in a northeastern Indian tertiary care hospital. J Infect Dev Ctries 9:725-731. doi: 10.3855/jidc.6336
Section
Original Articles