Antibiogram and Β-Lactamase Production Test of Multidrug Resistant Staphylococcus Species from Different Clinical Specimens

Abstract

The aim of this study is to isolate the multidrug resistant (MDR) staphylococci from various clinical specimens and test the β-lactamase enzyme in multidrug resistant staphylococci by chromogenic cephalosporin sticks. Total of 205 were isolated and identified as Staphylococcus spp. using standard microbiological technique. The isolates were classified as S. aureus and CONS based on slide and tube coagulase test. The percentage of S. aureus and CONS isolates were 67% and 33% respectively. Thus identified 98 (47.8%) staphylococci were screened as multidrug resistant by employing Kirby-Bauer disc diffusion method as recommended by Clinical Laboratory Standard Institute (CLSI 2006). On sensitivity assay of S. aureus, vancomycin and nitrofurantoin were 95.6% and 100% sensitive respectively. S. aureus were highly resistant to ampicillin (74.5%), nalidixic acid (74.2%) and oxacillin (61.7%). CONS were also highly sensitive to vancomycin and nitrofurantoin with 97.1% and 100% respectively. CONS were highly resistant to oxacillin (66.7%), cloxacillin (62.5%) and nalidixic acid (56.8%). Of the total S. aureus and CONS isolates 48.9% and 45.5% were multidrug resistant. Prevalence of MDR was found higher in male (51.1%) and age group 70-79 (66.7%). About 46.4% of OPD isolates were MDR. The multidrug resistant staphylococci on nitrocefin stick test revealed that 47% were β-lactamase producers. Among them 46.3% and 51.6% were S. aureus and CONS respectively. β-lactamase producers were highly resistant to ampicillin, cephalexin and nalidixic acid each with 93.8% resistance. On a comparative study of cloxacillin disc of various manufacturing companies, cloxacillin disc from HI-MEDIA, S. aureus and CONS showed 96% and 97.13% resistance respectively. However, for OXOID and MAST showed equal resistance of 56.25% and 61.7% respectively. Staphylococci isolated were highly sensitive to Nitrofurantoin and Vancomycin. β-lactamase positive staphylococci were highly resistant toward multiple of antibiotics. This suggests the need for the β-lactamase test prior to the antibiotic prescription.