PREVALENCE OF METHICILLIN RESISTANCE AMONG CLINICAL ISOLATES OF STAPHYLOCOCCUS AUREUS IN ZARIA METROPOLIS, KADUNA

Abstract

The emergence of antibiotic-resistant strains of S. aureus such as Methicillin-resistant S.
aureus (MRSA) is a worldwide problem in clinical medicine.This study determines the
phenotypic and genotypic prevalence of MRSA (Methicillin resistant staph aureus) among
clinical isolates in three hospitals in Zaria, Nigeria. A total of 350 suspected staphylococcal
isolates from all specimens (blood, urine, high vaginal swab, wound swab, ear swab, urethral
swab) submitted to the laboratory microbiology unit of the selected hospitals were collected,
out of which 51 were identified as Staphylococcus aureus using microgen staph identification
kit. Disc agar diffusion method was used for the antibiotics susceptibility test while MIC test
strip was used for vancomycin susceptibility evaluation. Susceptibility of the isolates tested
against various antibiotics shows that a large number of Staph aureus isolates were generally
susceptible to gentamycin 96.1%, chloramphenicol 82.4%, ciprofloxacin 78.4%, vancomycin
76.5%, erythromycin 58.8% and teicoplanin 52.9%, while generally resistant to cefoxitin
98%, cefixime 100%, amoxicillin 100% and oxacillin 100%. The high percentage 100% of
MARI at ≥0.3 suggests that the isolates originate from an environment where antibiotics are
often used. Phenotypic MRSA evaluation showed that 98% of isolates were completely
resistant to cefoxitin antibiotic, while Phenotypic VRSA evaluation showed that 3.92% of
isolates were VRSA (vancomycin resistant staph aureus). 12(twelve) isolates that were
resistant to cefoxitin antibiotic were selected for genotypic evaluation for detection of
16SrRNA and mecA genes. All isolates amplified with 16SrRNA signifying all are Staph
Aureus. The result shows that 58% of the isolates harbors mecA gene. In conclusion, MRSA
is a major cause of Hospital Acquired Infection and increasingly, community-acquired
infection. It appears that there is a decline in the overall ability of different healthcare settings
to stop or reduce the spread of MRSA. If we do not control MRSA, we can predict that yet
more antibiotic-resistant and pathogenic strains will continue to emerge.