MOLECULAR CHARACTERIZATION OF ANTIBIOTIC RESISTANCE PLASMIDS IN SOME EXTENDED SPECTRUM β-LACTAMASE PRODUCING GRAM NEGATIVE BACTERIAL ISOLATES RESISTANT TO METHANO LIC EXTRACT OF CARICA PAPAYA
MOLECULAR CHARACTERIZATION OF ANTIBIOTIC RESISTANCE PLASMIDS IN SOME EXTENDED SPECTRUM β-LACTAMASE PRODUCING GRAM NEGATIVE BACTERIAL ISOLATES RESISTANT TO METHANO LIC EXTRACT OF CARICA PAPAYA
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Date
2014-03
Authors
ADENAIKE, OMOLARA
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Abstract
Some samples of ready-to-eat foods and drinks (‘zoborodo’, ‘kunun zaki’, smoked fish and ‘suya’) sold within the environs of Ahmadu Bello University, Zaria, Nigeria were assessed for the presence of antibiotic resistant E. coli and Klebsiella spp. The bacteria isolated were characterized using Microgen Gram negative identification kit and tested for their susceptibility to prepared concentrations of methanolic extracts of the leaves, stem-bark and root of Carica papaya using impregnated paper discs. Phytochemical screening revealed presence of more active constituents in the leaf extract than in the extracts of the root and stem-bark. All the organisms were found to be resistant to the Carica papaya methanolic extracts. Determination of β-lactamase production using nitrocefin-containing beta-lactamase identification sticks was carried out to test sensitivity of the rapid test. The test was found to produce false negatives and so had 12.9% sensitivity but 100% specificity when compared with disc diffusion test. Antibiogram of the test organisms to nine antibiotics showed 75% broad spectrum resistance (i.e. resistance to ampicillin or cephalothin), 35% ESBLs production (i.e. resistance to cefpodoxime or cefotaxime). Student t-test shows higher significant difference between the numbers of E. coli and Klebsiella spp. Resistant to the antibiotic tested in the study. Pearson’s correlation showed significant association between ESBLs production and multidrug resistance in the entire sample populations. A high percentage of the bacteria had Multiple Antibiotic Resistance (MAR) index greater than 0.2 which shows that the isolates were obtained from high risk environment. Duncan multiple range test (DMRT) showed that the mean of antibiotic resistance from isolates obtained from ‘suya’ was significantly higher than those obtained from ‘zoborodo’ or smoked fish. For the molecular studies, TEM and SHV β-lactamase genes were assayed for among 12 isolates. TEM had a frequency of 66.7% while SHV had 8.3%. No isolate was found to harbour both TEM and SHV genes together. Sequence analysis results showed that the blaTEM in Sye10 (isolate 8) had 86% homology with β-lactamase TEM-1gene. The entire blaTEM genes were not sequenced, so it cannot be stated categorically that the entire TEM genes present were TEM-1. Sequence analysis of blaSHV in Syk2 (isolate 10) could not confirm the subtype. The reason for this is not yet known but must be because the primers only amplified a portion of the blaSHV open reading frame and not the entire portion. Sperman’s correlation showed moderate correlation between the presence of any of the two genes and resistance to third generation cephalosporins. Therefore, there is no significant correlation (rs = 0.258) between the presence of any of the two genes and resistance to third generation cephalosporins (p>0.05).
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 IN MICROBIOLOGY
DEPARTMENT OF MICROBIOLOGY,
FACULTY OF SCIENCE
AHMADU BELLO UNIVERSITY, ZARIA
NIGERIA
MARCH, 2014
Keywords
MOLECULAR,, CHARACTERIZATION,, ANTIBIOTIC,, RESISTANCE,, PLASMIDS,, EXTENDED,, SPECTRUM,, β-LACTAMASE,, PRODUCING,, GRAM,, NEGATIVE,, BACTERIAL,, ISOLATES,, RESISTANT,, METHANOLIC,, EXTRACT,, CARICA.