Thesis Abstract

<p> The emergence of multiple antibiotic resistance in bacteria and the indiscriminate use of antibiotics contribute to the dissemination of resistant pathogens in the environment which may cause problems in therapy and is a serious public health issue. This study was conducted to determine the incidence of <em>Pseudomonas aeruginosa</em>&nbsp;and <em>E.coli</em>&nbsp;isolates in certain clinical and environmental samples as well as to determine the susceptibility patterns of these isolates to some commonly used antibiotics. The organisms were isolated using standard microbiological techniques and the antibiotic susceptibility was determined using disc diffusion method while plasmid curing was done using sodium dodecyl sulphate (SDS). The result of this studies showed that most of the clinical and environmental isolates were more resistant to amoxacillin and augumentin but clinical isolates showed higher resistance. It was also observed that clinical isolates showed least resistance to gentamycin, ofloxacin, and ciprofloxacin; similar least resistance were observed in environmental samples with gentamycin and ciprofloxacin. There was a significant difference (P≥ 0.05) in the percentage resistance between the clinical and environmental isolates. Thirteen isolates that were resistant to more than seven antibiotics were subjected to plasmid curing using 1% and 5% SDS. It was observed that at treatment with 1% SDS some of the isolates became resistant to more than one antibiotic; when SDS was increased to 5%, some of the isolates that were resistant become completely sensitive to all the antibiotics used. However, one of the<em>P.aeruginosa</em>&nbsp;that was initially sensitive to chloramphenicol became completely resistant at 5% SDS and another isolate of <em>P.aeruginosa</em>&nbsp;that was initially sensitive to septrin, sparfloxacin and ciprofloxacin became completely resistant at 1% and 5% SDS. This study indicates that <em>P.aeruginosa</em>&nbsp;and <em>E.coli</em>&nbsp;isolated from clinical samples were more resistant to antibiotics than those isolated from environmental samples. It has as well shown that there may be a possible transfer of resistance from one strain to another. <br></p>

Thesis Overview

<p> </p><p><strong>1.0 INTRODUCTION AND LITERATURE REVIEW</strong></p><p><strong>1.1 Introduction</strong></p><p>The discovery of antibacterial agents had a major impact on the rate of survival from infections. However, the changing patterns of antimicrobial resistance caused a demand for new antibacterial agents. Therefore, the emergence of bacterial resistance to most of the commonly used antibiotics is of considerable medical significance (Khan and Malik, 2001; Oteo <em>et al.</em>, 2002).</p><p>Antibiotic resistance genes in most bacteria are frequently found in extra chromosomal elements known as R-plasmids. <em>Pseudomonas aeruginosa</em>&nbsp;is naturally resistant to many of the widely used antibiotics, so chemotherapy is often difficult (Dubois <em>et al.</em>, 2001).</p><p>Resistance is due to a resistance transfer plasmid (R-plasmid) which is a plasmid carrying gene encoding proteins that detoxify various antibiotics (Poole, 2004). Antibiotic resistant bacteria are widespread. Several antibiotic resistant genes can be carried by a single R-plasmid or alternatively, a cell may contain several R plasmids. In either case, the result is multiple resistance (Madigan <em>et al.</em>, 2009).</p><p><em>Escherichia coli </em>is a Gram negative bacterium and the main aerobic commensalbacterial species (Alhaj <em>et al</em>., 2007; Von and Marre, 2005). The native habitat of <em>Escherichia</em>&nbsp;<em>coli </em>is the enteric tract of humans and other warm-blooded animals. Therefore,<em>&nbsp;Escherichia coli </em>is widely disseminated in the environment through the faeces of humans and otheranimals and its presence in water is generally considered to indicate faecal contamination and the possible presence of enteric pathogens. <em>Esherichia coli</em>&nbsp;is able to acquire antibiotic resistance easily. Antibiotic resistant <em>Esherichia coli</em>&nbsp;may pass on the genes responsible for antibiotic resistance to other species of bacteria, such as <em>Staphylococcus aureus</em>, through a process called horizontal gene transfer (Dubois <em>et al.,</em>&nbsp;2001).</p> <br><p></p>