Abstract. A study of the etiologies of diarrhea in adults in relation to their human immunodeficiency virus (HIV) serostatus and number of CD4ϩ cells was carried out in the Central African Republic. In cases and controls, multiparasitism was observed. Salmonella spp. were identified mainly during acute diarrhea, with 50% of the S. enteritidis isolated during the study being responsible for septicemia and/or urinary tract infection in immunodeficient patients. Enteroaggregative Escherichia coli (EAggEC) were the most frequently identified agent in HIVϩ patients with persistent diarrhea; 42.8% of the patients with EAggEC as sole pathogens had bloody diarrhea, and these strains were negative for the presence of a virulence plasmid. Coccidia were found in those with acute and persistent diarrhea. Blood was observed in 53.3% of infections involving coccidia as the sole pathogen. Microsporidium spp. and Blastocystis hominis were found only in HIVϩ patients with persistent diarrhea. Shigella spp., Campylobacter spp., and Entamoeba histolytica were found in HIVϩ and HIVϪ dysenteric patients; bacteria resembling spirochetes that could not be cultivated were identified only in HIVϩ cases with dysentery. Shiga-like toxin-producing E. coli O157:HϪ was isolated from two cases with hemolytic-uremic syndrome. Fungi were identified as the sole pathogen in 6.4% of the HIVϩ patients with persistent diarrhea. Most of enteropathogenic bacteria identified were resistant to ampicillin and trimethoprim-sulfamethoxazole, remained susceptible to ampicillin plus clavulanic acid, and were susceptible to amikacin, gentamicin, and ciprofloxacin.

In human immunodeficiency virus (HIV)-infected adults from the Central AfricanRepublic, the occurrence of chronic diarrhea due to HEp-2 adherent Escherichia coli (EAEC) harboring virulence markers (eaeA, BFP, EAF, astA determinant of EAST/1, positive FAS test, enteropathogenic E. coli O serogroup) was shown to be associated with AIDS. We also show that EAEC that produce verotoxin (Stx2) but do not harbor the genetic markers for classical enterohemorrhagic E. coli are involved in hemorrhagic colitis and hemolytic-uremic syndrome in patients with HIV.The Central African Republic is strongly affected by the human immunodeficiency virus (HIV) epidemic (24). Nearly 72% of the adults hospitalized with AIDS present initially with chronic diarrhea (CD) (14). Between 1996 and 1999 we used phenotypic (14) and genotypic assays to study 88 HIV-infected adults hospitalized in Bangui and their matched controls to determine the clinical significance of diarrheagenic Escherichia coli (7,8,9,10,12,16,22,25,27,29,31,32,34,35). The methods were as previously described (14). To be included in the study, the patients had to be HIV positive and aged 18 or over, have CD (3 or more loose watery stools per day for at least 14 days [3]), have E. coli in a stool sample, and give informed consent. Each patient was matched with a control recruited from among the neighbors and family members of the patient. The matching criteria dictated that the control be aged within 5 years of the patient's age and of the same sex. The recruitment criteria for the matched controls were as follows: testing positive for HIV antibodies, having had no diarrhea on the day of recruitment or during the previous month, and having E. coli in their stools on the day of recruitment. All controls gave informed consent to participate.HEp-2 adherent E. coli (EAEC) (5, 28) with localized adherent (LA), aggregative adherent (AA), or diffuse adherent (DA) patterns were more common in the patients (P Ͻ 10 Ϫ5 ) than in the controls (Table 1). Some EAEC exhibited a strong LA pattern (16 patients versus no control) in which Ͼ20% of the randomly selected cells had attached bacteria (11,19).These LA strains with a strong LA pattern were associated with CD, especially when the assays used to identify enteropathogenic E. coli (EPEC) virulence factors yielded positive results (eaeA, EPEC adherence factor [EAF] plasmid, bundleforming pili [BFP] PCR, and fluorescent actin staining [FAS] test) (P Ͻ 10 Ϫ5 ), and all belonged to known EPEC O serogroups (P ϭ 0.0001). The isolation of enteroaggregative E. coli (EAggEC) was strongly correlated with the presentation of CD (P Ͻ 10 Ϫ5 ). The difference in the isolation rates of EAEC strains exhibiting DA between patients and controls was only significant when the presence of the astA gene encoding EAST/1 was considered (P ϭ 0.016); astA was located on 7-to 40-kb plasmids.Interestingly, all of the enteric bacteria isolated from 42 patients (86% of the 49 patients with severe immunodepression) harboring EAEC with virulence factors were E. co...

No abstract

Escherichia coli O157:H7 producing Shiga like toxins is a food-borne pathogen frequently isolated in Bangui from patients with hemorrhagic colitis (HC). This survey provides comprehensive data on the high prevalence of E. coli O157:H7 infection in Bangui: carriage of E. coli O157:H7 by zebu (Bos indicus) and fish, contamination of the fields at N'Goila where the butchers kill the zebus, and contamination of the field surface water along the M'Poko River upstream of the Oubangui River where fish are caught, appear to be important contributory factors. We also describe novel strains of serogroup O157:NM isolated from zebu and from fish; a variety of assays indicate that these strains belong to the enteropathogenic pathotype, though they lack certain genetic elements thought to be diagnostic for this pathotype.