Molecular Epidemiology of Escherichia Coli in HIV-Positive Individuals in South west Nigeria

Abstract

Introduction

Escherichia coli infection is a major health concern for human immunodeficiency virus (HIV)/AIDS patients because it is a substantial cause of diarrhoea-associated morbidity and mortality.

Materials and Methods

Stool and blood samples were collected from 879 HIV/AIDS patients in a tertiary hospital in southwest Nigeria. The blood samples were screened for HIV IgM using competitive ELISA, and the concentration of the IgM was determined. The stool samples were cultured on eosin methylene blue agar. The isolates were characterised based on the production of green metallic sheen on EMB agar..DNA was extracted from all the isolates, and the extracted DNA was analysed by PCR with primers specifically targeting the virulence genes of enterohemorrhagic E. coli (EHEC), enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC), and enteroinvasive E. coli (EIEC). Statistical analysis was conducted using the openepi online epidemiological package.

Results

All the blood samples tested positive for HIV IgM antibodies, and 80% had high concentration. All the stool samples were positive for E. coli, based on cell culture and DNA extraction. Of all the DNA tested by PCR using gene-specific primers targeting the 4 strains of E. coli, 222 samples were positive for EHEC shiga toxin 1 (stx1) gene, 212 samples were positive for EPEC intimin (eaeA) gene, 289 were positive for EHEC serotype O157:H7 using the stx2a&b gene, 125 were positive for EIEC haemolysin (hlyA) gene, and 31 were positive for ETEC uid gene.

Discussion

The high prevalence of E. coli O157:H7 is an indication that this strain, which has been previously linked with diarrhoea-related mortality in infants, may be responsible for most of the cases seen in HIV/AIDS patients. Though this strain is not common in adults, its involvement in HIV/AIDS is indicative of suppressed immunity in this group of people. Other strains are also present in significant proportions, indicating that these strains also constitute a public health concern, because they may be transmitted to infants or other immunocompromised individuals.