MOLECULAR IDENTIFICATION OF SOME ANTIBIOTIC RESISTANCE GENES OF STAPHYLOCOCCI ISOLATED FROM CHRONIC SKIN ULCER PATIENTS IN KADUNA STATE, NIGERIA.

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
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