Studies on the occurrence of beta-lactamases in members of the genera salmonella and shigella isolated from various hospitals

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>