MOLECULAR IDENTIFICATION OF SOME ANTIBIOTIC RESISTANCE GENES OF STAPHYLOCOCCI ISOLATED FROM CHRONIC SKIN ULCER PATIENTS IN KADUNA STATE, NIGERIA.
MOLECULAR IDENTIFICATION OF SOME ANTIBIOTIC RESISTANCE GENES OF STAPHYLOCOCCI ISOLATED FROM CHRONIC SKIN ULCER PATIENTS IN KADUNA STATE, NIGERIA.
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Date
2015-08
Authors
BABA, John
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Abstract
Molecular identification of someantibiotic resistance genes of staphylococci isolated from
chronic skin ulcer patients in Kaduna state was investigated. Pure staphylococci isolates were
characterized phenotypically before subjecting them to screening for antibiotic resistance
genes using using the Polymerase chain reaction (PCR) technique. The total number of
samples collected from the patients across four hospitals in Kaduna state from January 2012
to January 2013 was two hundred and ninety-two (292). Staphylococcus aureus ranked
highest among the species of staphylococci isolated from the chronic skin ulcer patients
(n=18, 34%), while Staphylococcus epidermidishad the highest number of isolates (n= 10,
18.9%) among the coagulase-negative staphylococci.The highest number of the
Staphylococci isolates was found among leg ulcers (n=28, 52%). The commonest resistance
pattern demonstrated by the Staphylococcus aureus to some antibiotics is in the order,
Cefoxitin (methicillin) , Amoxiclllin-clavulanic acid , which was exhibited by 72% of the
isolates.The resistance pattern of coagulase-negative staphylococci (CoNS) followed the
same trend as in S.aureus.Staphylococcus aureus exhibited 100% resistance to Amoxicillin -
clavulanic acid. Percentage resistance of coagulase-negative staphylocci revealed that all the
Coagulase-negative Staphylococci, except Staphylococcus intermedius showed 79%
resistance to Cefoxitin on the average basis. The Minimum Inhibitory Concentrations
(MICs) of the antibiotics on S.aureus isolates showed that 12(67%) of the isolates were
susceptible to Amoxicillin - Clavulanic acid at the concentration of 32.0µg/ml. The same
pattern was observed for the Coagulase-negative Staphylococci, where 13(52%) of the
isolates were also susceptible to Amoxicillin - Clavulanic acid at the same concentration of
32.0µg/ml. For the Minimum Bactericidal Concentrations (MBCs), over 50% of the isolates
of S.aureus and coagulase-negative staphylococci were killed at the highest concentration of
32.0µg/ml for almost all the antibacterial agents used, except for Ciprofloxacin where an isolate each of S.aureus and coagulase-negative staphylococci were killed at the
concentration of 8.0µg/ml. Polymerase chain reaction (PCR) analysis indicated the presence
of resistance genes such as blaZ (173bp), tetM (158bp) and mecA (314bp) in the
staphylococci species as depicted by the bands of the gel electrophoresis. The statistical
analysis of the socio-demographic factors using the chi-square (ᵪ2) test of association
showed that variables such as age, sex, educational status, occupation, cause of ulcer, site of
ulcer and type of urbanization were statistically significant for the occurrence of chronic skin
ulcer in the patients at P- value ≤ 0.05. The study showed that there was high prevalence of
MRSA and MRCoNS with possible transmission from the hospital to the community and
vice versa.The isolates of MRSA and MRCoNS were also resistant to other antibiotics apart
from cefoxitin. The resistance to the antibiotics by the isolates is as a result of some antibiotic
resistance genes in them.The socio-demographic factors could influence the occurrence of
chronic skin ulcer in the patients as indicated by the result of the statistical analysis.
Description
A DISSERTATION SUBMITTED TO THE SCHOOL OF POSTGRADUATE
STUDIES, AHMADU BELLO UNIVERSITY, ZARIA
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD
OF A DOCTOR OF PHILOSOPHY DEGREE (Ph.D) IN MICROBIOLOGY
DEPARTMENT OF MICROBIOLOGY
FACULTY OF SCIENCE
AHMADU BELLO UNIVERSITY, ZARIA
NIGERIA
Keywords
MOLECULAR IDENTIFICATION,, ANTIBIOTIC RESISTANCE GENES,, STAPHYLOCOCCI ISOLATED,, CHRONIC SKIN ULCER PATIENTS,, KADUNA STATE,, NIGERIA