Abstract:
Objective: To determine the in vitro susceptibility of chloramphenicol against methicillin-resistant Staphylococcus aureus.
Study Design: Cross-sectional study.
Place and Duration of Study: Department of Microbiology, Armed Forces Institute of Pathology, Rawalpindi, from
January to June 2012.
Methodology: One hundred and seventy four isolates of methicillin-resistant Staphylococcus aureus were included in this
study using cefoxitin (30 ìg) disc for detection. Minimum inhibitory concentration (MIC) of chloramphenicol against MRSA
was determined by using E-strip (AB BIO DISK). The susceptibility was determined by swabbing the Mueller-Hinton agar
(MHA) plates with the resultant saline suspension of MRSA and applying E-strip of chloramphenicol from AB Biodisk
Sweden and determining the MIC of chloramphenicol (in ìg/ml). Clinical and Laboratory Standards Institute (CLSI)
recommendations of ² 8 ìg/ml being sensitive, 16 ìg/ml as intermediate and ³ 32 ìg/ml as resistant were followed in
interpreting the results.
Results: Out of the 174 MRSA isolates, 132 (75.86%) isolates were susceptible to chloramphenicol with MICs of ² 8
ìg/ml, 38 (21.84%) were resistant ³ 32 ìg/ml while 4 (2.30%) were in intermediate range with MIC of 16 ìg/ml.
Conclusion: Chloramphenicol has shown good in vitro activity against MRSA and is likely to have a key role in the
treatment of MRSA infections providing us a good alternative to newer expensive antimicrobials in resource limited
countries.
