Duodenal ulcer promoting gene (DupA), plasticity region genes and sigma factors in H. pyloristrains from Nigeria.

INTRODUCTION: Helicobacter pylori is a principal cause of gastric cancer. The aim of this study was to determine the prevalence and contribution of duodenal ulcer promoting gene A (dupA), the plasticity region genes and sigma factors in relation to their pathological expression of H. pylori infections in the Nigerian population. METHODOLOGY: Polymerase Chain Reaction was used to analyze a total of forty-nine H. pylori strains isolated from patients attending various endoscopic units in tertiary hospitals in Nigeria for complete dupA (G27 variant), jhp0917, jhp0918, other plasticity region genes jhp 914/917, jhp0914, jhp0940 and sigma factors. RESULTS: PCR results indicated that the prevalence of complete dupA (G27 variants), jhp0917, jhp0918 and other plasticity region genes jhp0914, jhp0914/0917 and jhp0940 in the H. pylori strains were 4%, 53%, 88%, 73%, 12% and 0% respectively. The prevalence values of the sigma factors were 96%, 92%, 80% for rpoN,  fliA and rpoD respectively. However, the endoscopic findings showed that erosion, normal mucosal, ulcer, hyperaemic stomach, mucosal atrophy and oedematous stomach in the patients where the H. pylori strains were isolated were 40.8%, 32.7%, 10.2%, 8.2%, 2.0% and 6.1% respectively. There was significant association between jhp0917, jhp914/917 and G27 variant and the endoscopic findings, while other plasticity genes showed no association with the endoscopic findings. CONCLUSION: These results suggest that the presence of jhp0917, jhp0914/917 and G27 variant could be used as marker to predict the pathological effect of severity in Nigeria patients with H. pylori infection.

Clinical and Socio- Demographic Risk Factors for Acquisition of Helicobacter pylori Infection in Nigeria

Background: The aim of the study was to assess clinical and socio-demographic characteristics as well as prior drug usage as risk factors for Helicobacter pylori (H. pylori) infection in Nigeria. Methods: A total of 347 respondents were surveyed by assessing their clinical and socio-demographic characteristics in comparison with the non-invasive gold standard for H. pylori diagnosis, the urea breath test (UBT). Chi-square test and odds ratio analyses were conducted in order to assess if variables such as socio-demographic factors, drug intake, and history of ulcer/gastritis/ gastric cancer within the family significantly predicted test results. Results: A total of 130 (37.5%) respondents were positive for H. pylori by the UBT. Living with more than three people in an apartment and a history of ulcer/gastritis within the family were significantly associated with H. pylori (p ≤0.05), as well as current antibiotic intake (p ≤0.05). Nationality, stay outside Nigeria, level of education, main occupation, smoking and drinking habits, sources of drinking water, number of children and history of gastric cancer had no significant association with H. pylori infection (p ≥ 0.05). Conclusion: The results of the questionnaire revealed that most socio-demographic characteristics of the respondents had no significant association with H. pylori. Overcrowding, having siblings/parents with history of ulcer/gastritis as well as prior antibiotic usage had a significant association.

Serogenotyping and antimicrobial susceptibility testing of Salmonella spp. isolated from retail meat samples in Lagos, Nigeria.

Microarray-based serogenotyping, antimicrobial susceptibility tests and the detection of relevant resistance genes were performed on isolates of Salmonella spp. from retail meat samples obtained in Lagos, Nigeria. Out of 151 meat samples, 33 Salmonella isolates were obtained. Nine different Salmonella serovars (S. Amoutive, S. Bargny, S. Drac, S. Ealing, S. Urbana, S. Hadar, S. Nyborg, S. Anatum and S. Havana) were identified by microarray-based serogenotyping and confirmed afterwards using classical serotyping. Antibiotic susceptibility tests with 17 antibiotics showed that almost all isolates were fully susceptible to this panel. The results of this study indicated a high prevalence of Salmonella in retail meat, the presence of some previously rather rarely described Serovars in retail meat samples from Lagos, and a need to monitor for Salmonella and their antibiotic resistance determinants. The microarray-based system used herein proved to be perfectly suited as epidemiological tool to replace classical serotyping.

Molecular characterization of the circulating strains of Vibrio cholerae during 2010 cholera outbreak in Nigeria.

This study aimed at characterizing the phenotypic and toxigenic status of circulating strains of cholera during outbreaks in Nigeria, employing molecular typing techniques. Two hundred and one samples of rectal swabs, stool, vomitus, water (from the well, borehole, sachet, stream, and tap) and disinfectants (sodium hypochlorite) were collected from three states in the country. The samples were inoculated on thiosulphate-citrate bile salt-sucrose (TCBS), Cary-Blair transport medium and smeared on glass slides for direct examination. The Vibrio cholerae isolates were serotyped, biotyped, and characterized using PCR of the cytotoxin gene A (ctxA), wbeO1, and wbfO139 gene primer. Of the 201 samples screened, 96 were positive for V cholerae O1 (48%), with 69 (72%) positive for ctxA gene. The results from this study showed that the circulating strains of cholera in Nigeria were of Ogawa serotype, also observed in other outbreaks in Nigeria (1991, 1992, and 1996). However, the strains were of the Classical biotype and were mainly (72%) ctxA gene-positive. This current investigation has confirmed the production of cholera toxin by the circulating strains, and this could be harnessed for possible cholera vaccine production in Nigeria.

An assessment of the emergency response among health workers involved in the 2010 cholera outbreak in northern Nigeria.

BACKGROUND: The 2010 cholera outbreak in northern Nigeria affected over 40,000 people, with a case fatality rate (CFR) of ≥3.75%. We assessed the emergency response of health care workers (HCWs) involved in case management. METHOD: This was a cross-sectional study with data collected through a self-administered questionnaire. Data entry and analysis were performed using Epi info software. RESULTS: A total of 56 HCWs were interviewed. The mean age was 31 years (SD±8.16 years). The majority of the HCWs (80%; n=45) were aged 18-39 years. Most were community health extension workers (60%), and 3.6% (n=2) were medical doctors. Many of the HCWs had less than 2 years of work experience (42%). Additionally, 82% of the respondents had <1 week of cholera emergency response training, and 50% of the HCWs managed >20 suspected cases of cholera per day. Although 78% of HCWs reported the practice of universal safety precautions, 32% (n=18) knew HCWs who developed symptoms of cholera during the epidemic, most of which was believed to be hospital acquired (78%). We also found that 77% (n=43) of HCWs had no access to the required emergency response supplies. CONCLUSION: Inadequate training, a lack of qualified HCWs and a limited supply of emergency response kits were reported. Therefore, the government and stakeholders should address the gaps noted to adequately control and prevent future epidemics.

Molecular characterization of Salmonella spp directly from snack and food commonly sold in Lagos, Nigeria.

Food borne Salmonella infection is an important cause of morbidity and mortality. A total of 200 food samples commonly sold in Lagos, Nigeria comprising raw and cooked meat as well as meat products and spoilt meat were analysed for the presence of Salmonella spp using REVEAL serology kit, culture methods employing RPVA (Rappaport Vassiliadis agar), SSA (Salmonella-Shigella agar) and BSA (brilliant sulphite agar) and PCR method for direct detection from samples using primer salm3/4 and ST11/ST15 sets. Using the REVEAL serology kit, 74% of the samples were positive for Salmonella spp, while culture methods showed only 19% to be Salmonella spp. The PCR method revealed that Salmonella spp was present in 62% and 54% of the samples using primer set salm3/4 and ST11/ST15, respectively. However, the primer set ST11/ST15 was more reliable in the identification of Salmonella spp directly from food samples. These tools should prove useful in the continuous monitoring and control strategies especially for ready-to-eat foods, as well as in retail meat outlets, slaughter houses, fast food restaurants for the prevention and reduction of this pathogen that is of significant importance in the food industry.

Application of a point-of-care test for the serodiagnosis of typhoid fever in Nigeria and the need for improved diagnostics.

INTRODUCTION: There is an urgent need for affordable point-of-care diagnostics for the differentiation of febrile illnesses and the confirmation of typhoid in endemic countries. METHODOLOGY: Blood samples were collected from febrile patients with clinical suspicion of typhoid and screened for typhoid fever using the Widal and Typhi Dri Dot tests, while stool and blood samples were screened for Salmonella Typhi using the culture method as well as PCR as a confirmatory test. RESULTS: A high proportion of febrile patients from Lagos with clinical suspicion of typhoid fever reacted positively in a simple and rapid latex agglutination assay for typhoid fever, indicating that this illness is a common and presumably under-diagnosed health problem in this metropolis. Seropositivity was 19.2% in the rapid test compared with 22.9% in the classical Widal test. The confirmation of typhoid in these seropositive patients appeared cumbersome because of negative blood cultures and low DNA yield in molecular testing. A review of the literature revealed that in Nigeria seroprevalence rates can be high in the normal population and that pathogens other than S. Typhi are often isolated from the blood of seropositive febrile patients. CONCLUSION: The simplicity and the relatively high specificity (97.8%) of the rapid test as determined in a study performed in Indonesia calls for a further validation of this promising test for use in Africa.