PHENOTYPIC AND GENOTYPIC CHARACTERIZATION OF VANCOMYCIN RESISTANT STAPHYLOCOCCUS AUREUS ISOLATED FROM IN-PATIENTS IN SELECTED HOSPITALS IN KADUNA METROPOLIS, KADUNA STATE NIGERIA
PHENOTYPIC AND GENOTYPIC CHARACTERIZATION OF VANCOMYCIN RESISTANT STAPHYLOCOCCUS AUREUS ISOLATED FROM IN-PATIENTS IN SELECTED HOSPITALS IN KADUNA METROPOLIS, KADUNA STATE NIGERIA
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Date
2017-10
Authors
USMAN, Aisha
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Abstract
Staphylococcus aureus is an important pathogen associated with various hospital-and
community-acquired infections as such it is regarded as a public health problem. Vancomycin
was an approved and highly recommended antibiotic worldwide for the treatment of infections
caused by S. aureus especially methicillin resistant S. aureus. This study was carried out in order
to phenotypically and genotypically characterize vancomycin resistant S. aureus isolated from
patients on admission in some selected hospitals in Kaduna metropolis, Kaduna state Nigeria. A
total of 300 skin swab samples were collected from patients on admission. The swab sticks were
inoculated into brain-heart infusion broth, transported to the laboratory and then inoculated on to
mannitol salt agar and blood agar. Isolates with the characteristic colonial morphology of the S.
aureus were then characterized microscopically and identified biochemically. The susceptibility
of S. aureus isolates to seven antibiotics was determined using Kirby-Bauer method.
Vancomycin minimum inhibitory concentration for the isolates was determined by broth dilution
method. The VRSA were confirmed by the detection of vanA gene in the isolates by polymerase
chain reaction. A total of 52 (17.33%) S. aureus isolates were obtained from skin swabs of inpatients
in selected hospitals in Kaduna metropolis based on microscopic and biochemical
identification. Multiple antibiotic resistance index analysis showed that the MAR indices of the
isolates were between 0.14 and 0.71. Most of the isolates had MARI values greater than 0.2
suggesting that the isolates were from high risk environment where antibiotics are frequently
used. Among the 52 isolates, 2 were vancomycin intermediate S. aureus (MIC value 4-8μg/ml)
another 2 were vancomycin resistant S. aureus (MIC values ≥ 16μg/ml) while the remaining 48
isolates were vancomycin susceptible S. aureus (MIC value ≤2μg/ml). PCR result for the
detection of vanA gene showed that all the 2 VRSA had the vanA gene. It then means the
resistance of the VRSA isolates was mediated by vanA gene. VRSA was characterized both
phenotypically (by determination of vancomycin susceptibility) and genotypically (by detection
of Van A gene) in this study. The occurrence of S. aureus and VRSA in this study was found to
be 17.33% and 3.85% respectively.
Description
A DISSERTATION SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES, AHMADU BELLO UNIVERSITY, ZARIA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF MASTER OF SCIENCE DEGREE IN MICROBIOLOGY DEPARTMENT OF MICROBIOLOGY, FACULTY OF LIFE SCIENCES, AHMADU BELLO UNIVERSITY, ZARIA
Keywords
PHENOTYPIC,, GENOTYPIC,, CHARACTERIZATION,, VANCOMYCIN RESISTANT,, STAPHYLOCOCCUS,, AUREUS ISOLATED,, IN-PATIENTS,, HOSPITALS, KADUNA,, NIGERIA