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Biomedical subjects

I N Okeke

Publications and source records attributed to I N Okeke.

14 recordsLinked to original sources
PubMed2004

Antibiotic resistance of faecal Escherichia coli from healthy volunteers from eight developing countries.

OBJECTIVES: To determine the prevalence of antibiotic-resistant faecal Escherichia coli from adult volunteers from urban (U) areas in Kenya, Mexico, Peru and the Philippines, and non-urban (NU) locations in Curacao, Mexico, Venezuela, Ghana, Zimbabwe and the Philippines. METHODS: Faecal samples of adult volunteers (n=1290) were analysed in one laboratory for the presence of antimicrobial-resistant E. coli using Eosin Methylene Blue agar plates containing, respectively, ampicillin, oxytetracycline, cefazolin, ciprofloxacin, gentamicin, chloramphenicol and trimethoprim at breakpoint concentrations. RESULTS: The mean age of the volunteers was approximately 35 years; most of them were female. Ciprofloxacin resistance was in the range 1%-63%: the highest percentages were found in the urban populations of Asia and South America. In Peru and the Philippines (U and NU), the prevalence of gentamicin resistance was >20%. Cefazolin resistance was the highest in the urban Philippines (25%). Higher prevalences for ampicillin, oxytetracycline and trimethoprim were found for urban areas compared with non-urban ones of Asia, Africa and South America, respectively (P<0.05). CONCLUSIONS: In the populations studied, antibiotic resistance in faecal E. coli from adult volunteers was emerging for cefazolin, gentamicin and ciprofloxacin and was high for the older drugs ampicillin, oxytetracycline, trimethoprim and chloramphenicol.

Adolescent↗
PubMed2001

Dissemination of antibiotic-resistant bacteria across geographic borders.

The development of antibiotic-resistant (AR) bacteria in any country is of global importance. After their initial selection and local dissemination, AR bacteria can be transferred across international borders by human travelers, animal and insect vectors, agricultural products, and surface water. The sources and routes of importation of strains of AR bacteria are most often unknown or undetected, because many bacteria carrying resistance genes do not cause disease, and routine surveillance often does not detect them. Control of international dissemination of AR bacteria depends on methods to reduce selection pressure for the development of such bacteria and improved surveillance to detect their subsequent spread.

Animals↗
PubMed2001

Enteroaggregative Escherichia coli.

Enteroaggregative Escherichia coli (EAEC) are an increasingly important cause of diarrhoea. E. coli belonging to this category cause watery diarrhoea, which is often persistent and can be inflammatory. EAEC have been implicated in sporadic diarrhoea in children and adults, in both developing and developed countries, and have been identified as the cause of several outbreaks worldwide. EAEC are defined by their ability to adhere to epithelial cells in a characteristic "stacked-brick" pattern but are otherwise highly heterogeneous. Genes that could contribute to the pathogenicity of EAEC encode adhesins, toxins, and other factors, all of which are only partially conserved. Practicable tools are needed to improve diagnosis and identify risk factors. EAEC-infected individuals can be treated with fluoroquinolones but there is a need to examine alternative treatment protocols.

Adhesins, Escherichia coli↗
PubMed2001

Bacteriological quality of skin-moisturizing creams and lotions distributed in a tropical developing country.

AIMS: To evaluate the bacteriological quality of skin moisturizing products in the South-west part of Nigeria and study factors predisposing their bacterial contamination under tropical conditions. METHODS AND RESULTS: Viable counts for bacteria exceeded 10(3) cfu ml(-1) or cfu g(-1) in 8 (16.3%) commercially available creams and lotions at time of purchase. Escherichia coli (8), Pseudomonas spp. (7), Staphylococcus spp. (9) and Bacillus spp. (6) were the most commonly recovered bacteria. Following use by volunteers, the proportion of E. coli and other Gram-negative organisms recovered increased. Organic matter, particularly in the absence of preservatives, enhanced survival and growth of bacteria in creams stored under ambient tropical conditions during challenge experiments. CONCLUSIONS: Contaminated products are relatively uncommon but some products present a potential health hazard because they are unable to suppress the growth of organisms of likely faecal origin during use. SIGNIFICANCE AND IMPACT OF THE STUDY: Quality assurance during manufacture, pack size, preservative evaluation, organic matter and water content were identified as factors to be considered during the development of creams and lotions for use in tropical developing countries.

Bacteria↗
PubMed2001

Comparative sequence analysis of the plasmid-encoded regulator of enteropathogenic Escherichia coli Strains.

Enteropathogenic Escherichia coli (EPEC) strains that carry the EPEC adherence factor (EAF) plasmid were screened for the presence of different EAF sequences, including those of the plasmid-encoded regulator (per). Considerable variation in gene content of EAF plasmids from different strains was seen. However, bfpA, the gene encoding the structural subunit for the bundle-forming pilus, bundlin, and per genes were found in 96.8% of strains. Sequence analysis of the per operon and its promoter region from 15 representative strains revealed that it is highly conserved. Most of the variation occurs in the 5' two-thirds of the perA gene. In contrast, the C-terminal portion of the predicted PerA protein that contains the DNA-binding helix-turn-helix motif is 100% conserved in all strains that possess a full-length gene. In a minority of strains including the O119:H2 and canine isolates and in a subset of O128:H2 and O142:H6 strains, frameshift mutations in perA leading to premature truncation and consequent inactivation of the gene were identified. Cloned perA, -B, and -C genes from these strains, unlike those from strains with a functional operon, failed to activate the LEE1 operon and bfpA transcriptional fusions or to complement a per mutant in reference strain E2348/69. Furthermore, O119, O128, and canine strains that carry inactive per operons were deficient in virulence protein expression. The context in which the perABC operon occurs on the EAF plasmid varies. The sequence upstream of the per promoter region in EPEC reference strains E2348/69 and B171-8 was present in strains belonging to most serogroups. In a subset of O119:H2, O128:H2, and O142:H6 strains and in the canine isolate, this sequence was replaced by an IS1294-homologous sequence.

Amino Acid Sequence↗
PubMed2000

Heterogeneous virulence of enteroaggregative Escherichia coli strains isolated from children in Southwest Nigeria.

Enteroaggregative Escherichia coli (EAEC) has been implicated in acute and persistent diarrhea, and most strains harbor a member of a partially-conserved plasmid family (called pAA). We studied EAEC isolated from Nigerian children aged <5 years to elucidate the roles of plasmid and chromosomal EAEC loci. We tested a total of 131 EAEC strains isolated from acute diarrhea case patients and control subjects for hybridization with 8 pAA plasmid-derived and 2 chromosomal gene probes, for several in vitro phenotypes and for resistance to antimicrobial agents. Using by multiple logistic regression, we found genes encoding the AAF/II fimbriae to be strongly associated with diarrhea in this population. EAEC strains appear to be of heterogeneous virulence, and data suggest that AAF/II may be a marker for pathogenic strains.

Case-Control Studies↗
PubMed2000

Characterization of Escherichia coli strains from cases of childhood diarrhea in provincial southwestern Nigeria.

In a study carried out in small-town and rural primary health care centers in southwestern Nigeria, 330 Escherichia coli strains isolated from 187 children with diarrhea and 144 apparently healthy controls were examined for virulence traits. Based on the results of colony blot hybridization, strains were categorized as enteropathogenic E. coli (1.8%), enterotoxigenic E. coli (2.4%), enteroinvasive E. coli (1.2%), enterohemorrhagic E. coli (0.6%), enteroaggregative E. coli (10.3%), diffusely adherent E. coli (7.9%), cell-detaching E. coli (6.9%), and cytolethal distending toxin-producing E. coli (0.9%). E. coli strains that hybridized with a Shiga toxin gene probe but lacked other characteristics usually present in enterohemorrhagic E. coli constituted 8.4% of the isolates. Ninety-seven E. coli isolates adhered to HEp-2 cells in an aggregative fashion but did not hybridize with any of the probes employed in the study. Overall the pathotypes, apart from cytolethal distending toxin-producing E. coli, were recovered both from children with diarrhea and from children without diarrhea, though to a lower extent from the healthy children. All diarrheagenic E. coli strains were associated with diarrhea (P < 0.02). Heat-stable-enterotoxin-producing enterotoxigenic E. coli showed significant association with diarrhea (P < 0.02), as did strains that demonstrated aggregative adherence to HEp-2 cells (P < 0.04), but not those that hybridized with the CVD432 enteroaggregative probe.

Child, Preschool↗
PubMed1999

Antimicrobial spectrum of Alchornea cordifolia leaf extract.

The 50% aqueous ethanol extract of Alchornea cordifolia (Schum and Thonn) Muell. Arg. leaf was screened for activity against 74 microbial strains representing aerobic, facultative and anaerobic bacteria as well as fungi. The panel of test strains included organisms from culture collections as well as clinical and environmental isolates. A concentration of 5 mg/mL of extract inhibited 36.5% of the isolates and 95.9% were inhibited by a concentration of 20 mg/mL. Only three strains, all filamentous fungi, were not susceptible to 40 mg/mL of the extract, the highest concentration tested. The extract showed the best activity against gram-positive bacteria and yeasts with inhibitory concentrations against these organisms being under 5 mg/mL. The results demonstrate that the A. cordifolia extract has a very broad spectrum of activity and suggests that it may be useful in the treatment of various microbial infections.

Anti-Bacterial Agents↗
PubMed1995

Bacterial capsules: a simple method for demonstration under the light microscope.

It is sometimes desirable to demonstrate bacterial capsules during the routine examination of clinical isolates. Apart from the Indian ink method, methods of demonstrating bacterial capsules are not only tedious but are often non-reproducible. A combined positive-negative capsule staining procedure which is simple, rapid and reproducible is described.

Bacteria↗
PubMedDate not supplied

Socioeconomic and behavioral factors leading to acquired bacterial resistance to antibiotics in developing countries.

In developing countries, acquired bacterial resistance to antimicrobial agents is common in isolates from healthy persons and from persons with community-acquired infections. Complex socioeconomic and behavioral factors associated with antibiotic resistance, particularly regarding diarrheal and respiratory pathogens, in developing tropical countries, include misuse of antibiotics by health professionals, unskilled practitioners, and laypersons; poor drug quality; unhygienic conditions accounting for spread of resistant bacteria; and inadequate surveillance.

Anti-Bacterial Agents↗
PubMedDate not supplied

Antibiotic resistance in Escherichia coli from Nigerian students, 1986 1998.

We tested 758 fecal Escherichia coli isolates, recovered from Nigerian students in 1986, 1988, 1990, 1994, and 1998, for susceptibility to seven antimicrobial drugs. The prevalences of strains resistant to tetracycline, ampicillin, chloramphenicol, and streptomycin were 9% to 35% in 1986 and 56% to 100% in 1998. These findings demonstrate that resistance gene reservoirs are increasing in healthy persons.

Adolescent↗
PubMedDate not supplied

Helicobacter pylori in the dental plaque and gastric mucosa of dyspeptic Nigerian patients.

BACKGROUND: Presence of helicobacter pylori (H.Pylori) in the dental plaques may be associated with the presence of the same organism in gastric mucosa. OBJECTIVES: To assess and compare the prevalence of H. pylori in dental plaques and gastric mucosa of dyspeptic Nigerians. METHODS: Sixty-six consecutive patients undergoing endoscopy for investigation of dyspepsia were included in the study. A predesigned questionnaire was used to collect information on socio-demographic and other factors. Each patient also had clinical dental examination. Dental plaque scrapping was collected before endoscopy for helicobacter pylori culture, and at endoscopy, two gastric biopsy specimens were taken for culture and histology. RESULTS: The mean age (+/- SD) of the patients was 44.8 (+/- 17.4) years (range 5 to 80 years). The positivity rate of helicobacter pylori in gastric biopsy was 35 of 66 (53.0%) while the same for dental plaque was 46 of 66 (69.7%). The correlation (Spearman's) between gastric mucosa and dental plaque colonization with helicobactor pylori was significant (R = 0.30, P = 0.01). When concordant positivity of gastric biopsy culture and histology was taken as diagnostic, the sensitivity of dental plaque culture was found to be 82.9% and the specificity was 45.2%. CONCLUSIONS: This study revealed that helicobactor pylori has a high prevalence in the dental plaque of the population that we have studied and may therefore be of potential relevance in screening for such infection.

Adolescent↗
PubMedDate not supplied

Quality and bioavailability of ampicillin capsules dispensed in a Nigerian semi-urban community.

Five samples of ampicillin capsules with a label claim of 250 mg were purchased from different dispensing points in a small town in Nigeria. The pharmaceutical quality of the products and a sample from a batch produced by a local manufacturer was evaluated and five of the capsule samples were employed in an in vivo bioavailability study. Three of the five capsule samples from dispensing points were found to be of lower quality than the officially prescribed standards of pharmaceutical quality. The quality lapses observed were sufficient to bring about determinable differences in biological availability. The results demonstrate that ampicillin capsules of sub-standard chemical quality are being dispensed within the study sources from authorised and unauthorised sources and that this may have biological, clinical and epidemiological consequences.

Ampicillin↗