Thesis Abstract

<p> </p><p><em>Salmonella </em>and<em>&nbsp;Shigella </em>species isolated from human faecal samples were examined forBeta-lactamase production and resistance to some antibiotic agents. Age distribution of sources of resistant isolates showed that<em>Shigella</em>&nbsp;isolates from Youths (18 – 30 years) were more resistant to Ampicillin (66.67%) and Augmentin (33.33%) than isolates from Infants (6 months – 4 years) which showed percentage resistance of 3% to Ampicillin and 0% to Augmentin. <em>Salmonella</em>&nbsp;species isolated from Adults (31 – above) were more resistant to Augmentin (45%) and Ampicillin (40%), than isolates from Youths (18- 31 years) which showed percentage resistance of 40% to Ampicillin and 36.67% to Augmentin. <em>Salmonella</em>&nbsp;isolated from Infants (6 months – 4 years) showed p ercentage resistance of 28.57% to Ampicillin and 14.29% to Augmentin while isolates from Children (5 – 17 years) showed percentage resistance of 25% to Ampicillin and 12.5% to Augmentin. Sex distribution of sources of resistant isolates showed that <em>Shigella</em>&nbsp;species isolated from males were more resistant to Ampicillin (100%) while isolates from Females were more resistant to Augmentin (50%). <em>Salmonella</em>&nbsp;species isolated from Males showed high percentage resistance to Augmentin (60%) while isolates from Females were more resistant to Ampicillin (57.14%).</p><p><em>Salmonella </em>species showed higher percentage resistance to commonly used antibiotic agentsthan <em>Shigella</em>species. The result showed that 8% of <em>Shigella</em>&nbsp;species and 21.5% of</p><p><em>Salmonella</em>species were resistant to more than eight antibiotics with multiple antibioticresistance (MAR) index ranging from 0.2-0.9. Presumptive results of resistance curing treatments showed that the resistance traits were plasmid borne. Agarose gel electrophoresis (AGE) showed plasmids with molecular weights clustered around 23.1kb for species of</p><p><em>Salmonella </em>and<em>&nbsp;Shigella</em>. Conjugative transfer of resistance determinants was demonstratedfrom <em>Salmonella</em>&nbsp;to E. coli and from <em>Salmonella</em>&nbsp;to <em>Shigella</em>&nbsp;but not from <em>Shigella</em>&nbsp;to E. coli or to <em>Salmonella</em>. Studies on Beta-lactamase production showed that 9 (81.82%) of <em>Shigella</em>&nbsp;species and 22 (61.11%) of <em>Salmonella</em>&nbsp;species were Beta-lactamase producers with 3 (27.27%) of <em>Shigella</em>&nbsp;species and 20 (55.56%) of <em>Salmonella</em>&nbsp;species producing extended spectrum Beta-lactamases (ESBLs). ESBLs production is an acknowledge threat to modern medicine which is antibiotic based.</p><p>&nbsp;</p> <br><p></p>

Thesis Overview

<p> </p><p><strong>INTRODUCTION AND LITERATURE REVIEW</strong></p><p><strong>1.1 &nbsp; &nbsp; &nbsp; &nbsp;</strong><strong>INTRODUCTION</strong></p><p>In human medicine, the most important family of bacteria is Enterobacteriaceae, which includes genera and species that cause well-defined diseases, as well as nosocomial infections. The members of this family are Gram-negative, rod-shaped, non-spore-forming facultative anaerobes that ferment glucose and other sugars, reduce nitrate to nitrite, and produce catalase but seldom oxidase. Most Enterobacteriaceae are components of the gastrointestinal flora of humans and animals, although many are also widespread in the environment. Furthermore, these bacteria can cause many different infections, such as septicaemia, urinary tract infections, pneumonia, cholecystitis, cholangitis, peritonitis, wound infections, meningitis, and gastroenteritis, and they can give rise to sporadic infections or outbreaks (Donnenberg, 2009).</p><p><em>Salmonella </em>and<em>&nbsp;Shigella </em>infections represent a major health problem worldwide, particularly indeveloping countries where they are recognized as the most frequent causes of morbidity and mortality (David and Frank, 2000, Mahbubur <em>et al.,</em>&nbsp;2007; Abdel <em>et al</em>., 2008). Life lost, together with the high costs to local public health care system, makes prevention and control a priority (Mahbubur <em>et al.,</em>&nbsp;2007; Yah <em>et al.,</em>&nbsp;2007a). The two pathogens have been associated with diarrhoea but the severity of the diarrhoea varies with the pathogens. Generally<em>Shigella</em>&nbsp;causes bloody diarrhoea while <em>Salmonella</em>&nbsp;induces non-bloody gastroenteritis. Antibiotic resistant<em>Salmonella</em>&nbsp;and <em>Shigella</em>&nbsp;are of global concern because they affect both developed and developing countries due to increased international travel (David and Frank, 2000, Dubois <em>et al., </em>2007).These concerns have been further reinforced in recent years by the emergence ofantimicrobial resistance among major groups of the enteric pathogens. The presence of antibiotic resistant bacteria from hospitalized patients throughout the world has been documented (Yah <em>et al.,</em>&nbsp;2007b).</p><p>Studies with <em>Salmonella</em>&nbsp;and <em>Shigella</em>&nbsp;are of particular relevance because these species can occupy multiple niches, including human and animal hosts (Martin <em>et al.,</em>&nbsp;1996, Levy, 1998; Khan, 2006). Reports have shown that the resistance of gastroenteric <em>Salmonella</em>&nbsp;and <em>Shigella</em>&nbsp;strains to antimicrobial agents is in large part due to the production of extended- spectrum β-lactamases (ESBLs) encoded on plasmids, as well as on the chromosome (David and Frank 2000).</p> <br><p></p>