Academic journal article Journal of Health Population and Nutrition

Aetiology of Diarrhoea and Virulence Properties of Diarrhoeagenic Escherichia Coli among Patients and Healthy Subjects in Southeast Nigeria

Academic journal article Journal of Health Population and Nutrition

Aetiology of Diarrhoea and Virulence Properties of Diarrhoeagenic Escherichia Coli among Patients and Healthy Subjects in Southeast Nigeria

Article excerpt

INTRODUCTION

Diarrhoeal diseases and other related gastrointestinal disorders are one of the most important causes of illness and death all over the world, particularly among infants and young children (1-3). The major causes of diarrhoeal illness include, among others, limited access to or poor quality of water, poor food hygiene, and sanitation. The bacterial pathogens usually responsible for diarrhoeal illness include Escherichia coli, Shigella, Salmonella, Campylobacter, Yersinia, Aeromonas, etc. (4). Although in developed countries and in a few developing countries, the mortality rates have declined considerably in recent times due to improvement in general hygiene and advances in healthcare, the problem still persists in so many other countries where outbreaks of diarrhoeal diseases continue to affect millions of infants and young children (4,5). The movement of persons within the same region and from one country to another increases the chance of transmission, thus requiring that comprehensive and first-hand information on peculiar situations in each locality or region be known.

Five major classes of diarrhoeagenic Escherichia coli (DEC) are associated with diarrhoeal diseases. These are: enterotoxigenic E. coli (ETEC), enteroinvasive E. coli (EIEC), enteropathogenic E. coli (EPEC), enterohaemorrhagic E. coli (EHEC), and enteroaggregative E. coli (EAEC). Some authors have proposed a sixth group: diffuse-adhering E. coli (DAEC) but this has not been clearly established (4,6). Each of the several classes of DEC is defined based on the distinct virulence characteristics. Similarly, tests for these characteristics have been developed to distinguish DEC classes from each other and from non-pathogenic E. coli strains of the normal flora (7,8). The epidemiological significance of each E. coli category in childhood diarrhoea varies with the geographical area. As expected, it has become clear that there are important regional differences in the prevalence of different categories of DEC. Several studies on the incidence of diarrhoeal illnesses caused by different classes of DEC have been conducted mainly in Latin America, Africa, South and Southeast Asia, and the Middle East (1). Study of the prevalence of DEC categories and their importance in diarrhoea has not been carried out extensively in Nigeria because only the southwestern axis has been well-studied, leaving the northern and southeastern areas (9-11).

Nigeria is a highly-populated country comprising so many cities having people of diverse socioeconomic and religious background. Enugu and Onitsha in the southeast flank are well-populated towns due mainly to the level of commercial activities going on in these cities. For instance, several people come to the city of Onitsha from other countries in West and East Africa and even beyond for one kind of commercial activity or the other. Sporadic endemic diarrhoea among adults and young children, however, contributes to the overall loss of productivity in developing countries and increases the risk that pathogens will be passed on to susceptible children or visitors. Therefore, to ascertain the level/spectrum of bacterial pathogens and to define the association of various categories of E. coli with diarrhoea in Enugu and Onitsha, Southeast Nigeria, a controlled study using the traditional culture/ serology technique and polymerase chain reaction (PCR) for the identification of specific virulence factors was undertaken.

MATERIALS AND METHODS

Collection of samples

In total, 520 stool samples were collected from infants and other age-groups (age 0-45 years), with cases of acute gastroenteritis attending both private and public hospitals/medical laboratories in Enugu and Onitsha in Southeast Nigeria. These patients presented varying kinds of symptoms, such as nausea, vomiting, fever, loss of appetite, abdominal pains, malaise, and watery stool. In other words, patients were enrolled in the study if they had diarrhoea characterized by frequent watery stools (>3 times per day) with or without blood or mucus and had not taken any antimicrobial agent in the week preceding sampling. …

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