International Journal of Current Microbiology and Applied Sciences (IJCMAS)
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Original Research Articles                      Volume : 9, Issue:6, June, 2020

PRINT ISSN : 2319-7692
Online ISSN : 2319-7706
Issues : 12 per year
Publisher : Excellent Publishers
Email : /
Editor-in-chief: Dr.M.Prakash
Index Copernicus ICV 2018: 95.39
NAAS RATING 2020: 5.38

Int.J.Curr.Microbiol.App.Sci.2020.9(6): 3576-3585

In-vitro Evaluation of Antibiotic Combination Effect between Gentamicin and Penicillin G against Methicillin Resistant Staphylococcus aureus (MRSA) by Checkerboard Technique
Emmanuel C. Ezeobiora1* and Vincent C. Okore2
1Department of Pharmaceutics and Pharmaceutical Technology, Faculty of Pharmacy, University of Lagos, Lagos, Nigeria
2Department of Pharmaceutics and Pharmaceutical Microbiology, University of Nigeria, Nsukka
*Corresponding author

Methicilin–resistant Staphylococcus aureus (MRSA) is a common cause of serious nosocomial infections with limited options for treatment due to its known resistance to many antibiotics. Knowledge guided antibiotic combination therapy can be of great benefit in fighting this superbug. The aim of this study was to evaluate the combined activity of penicillin G (A) and gentamicin (B) against clinical isolates of methicillin resistant Staphylococcus aureus. Ten clinical isolates of MRSA were labeled as S15, S31, S41, S42, S44, S46, S48, S50, S55 and S57.  They were confirmed through microscopical examination and non susceptibility to oxacillin disk. The antibiotic combination effect of penicillin G and gentamicin was evaluated by checkerboard technique. The minimum inhibitory concentration (MIC) of each antibiotic was determined by broth dilution technique. The interaction between the two antibiotics in combination was evaluated algebraically by calculating their fractional inhibitory concentration (FIC) index according to the relationship: FIC index= FICA + FICB. The MIC values of penicillin G (A) and gentamicin (B) for the ten strains were at range of 5µg/ml - 40µg/ml and 1µg/ml - 8µg/ml respectively. The antibiotic combination effect showed synergism in most combination ratios except S44, S46, S48 and S57 where penicillin G: gentamicin (9:1) ratio showed additivity. More so, S42 showed additivity in three combination ratios of 9:1, 8:2 and 1:9. As the ratio of penicillin G to gentamicin increased, synergism dropped to additivity in those combinations where synergism was not recorded. In Conclusion, the combination of penicillin G and gentamicin has a clinical significance for use in antimicrobial therapy involving the disease states caused by methicillin resistant Staphylococcus aureus. The use of such combination must be with greater ratio of gentamicin than penicillin G.

Keywords: Penicillin G, Gentamicin, Methicillin resistant Staphylococcus aureus, Checkerboard technique

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How to cite this article:

Emmanuel C. Ezeobiora and Vincent C. Okore. 2020. In-vitro Evaluation of Antibiotic Combination Effect between Gentamicin and Penicillin G against Methicillin Resistant Staphylococcus aureus (MRSA) by Checkerboard Technique.Int.J.Curr.Microbiol.App.Sci. 9(6): 3576-3585. doi:
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