Abstract

Objective: To estimate the frequency of antibiotic resistance among the Staphylococci against a set of beta (β) lactam group of antibiotics.
Methodology: A total of 156 cultures of Staphylococci were isolated from clinical specimens and based on the coagulase production were categorized into two groups as; Coagulase Positive Staphylococci (CoPS) and Coagulase Negative Staphylococci (CoNS). The antibiotic resistance was determined using Kirby Baur disc diffusion method.
Results: Out of 156 isolates 57.6% (n=90) isolates were from male patients while 42.4% (n=66) were from female patients. About 62.1 % (n=97) of the isolates were CoPS while 37.9 % (n=59) were CoNS. Among CoPS the highest percentage of resistance (97.9%) was observed against penicillin G whereas among the CoNS the highest resistance was observed against Cefixime (93.2%). The comparative analysis for their potential to resist various members of beta-lactam antibiotics between CoPS and CoNS suggested non-significant differences for majority of the antibiotics used in this study. Comparatively higher resistance against amoxicillin was seen for CoPS (92.7%) than CoNS (79.6%). The odd ratio (OR) and confidence interval (CI 95%) for amoxicillin resistance between CoPS vs CoNS was calculated to be: 3.28 ( 1.21 – 8.89), while the p-values were determined to be 0.015 using chi square test of independence applying 2x2 contingency table. These values suggest a significant association of amoxicillin resistance with CoPS.
Conclusion: In general, beta-lactam antibiotic resistance in Staphylococcal isolates is observed greater in Hyderabad as compared to the previously described resistance in other regions of Pakistan.

Key words: Staphylococcus aureus, Coagulase-Negative Staphylococci (CoNs), beta-lactam antibiotics.