Muinah A Fowora

Application of stool-PCR for the diagnosis of Helicobacter pylori from stool in Nigeria- a pilot study

There are various methods for detection of Helicobacter pylori and the gold standard for non-invasive detection is the urea breath test (UBT). The aim of the study is therefore to detect H. pylori from the stool of patients with dyspepsia by PCR and compare results obtained with UBT. A total of 97 stool samples from patients presenting with dyspeptic symptoms in Lagos University Teaching Hospital (LUTH) were screened for urea breath test (UBT) and the presence of H. pylori DNA using stool-PCR. Out of 97 stool samples analysed, 38 (39.2%) were positive for Helicobacter spp. and 20 (20.6%) positive for H. pylori by PCR, through amplification of 16S rRNA and glmM genes respectively. Of the 20 positive by glm M gene, the cagA gene was detected in 8 (40%) samples, while 47 (48.5%) out of 97 stool samples were positive for H. pylori by UBT. The sensitivity and specificity of the glmM gene compared with UBT as the gold standard is 42.6% and 100% respectively. The positive predictive value (PPV) was 100% while the negative predictive value (NPV) was 60%.The method may be useful for detecting H. pylori from stool amongst children especially where most hospitals lack endoscope for children although the method is expensive.

Helicobacter pylori strains from a Nigerian cohort show divergent antibiotic resistance rates and a uniform pathogenicity profile

Antibiotic resistance in Helicobacter pylori is a factor preventing its successful eradication. Particularly in developing countries, resistance against commonly used antibiotics is widespread. Here, we present an epidemiological study from Nigeria with 111 isolates. We analyzed the associated disease outcome, and performed a detailed characterization of these isolated strains with respect to their antibiotic susceptibility and their virulence characteristics. Furthermore, statistical analysis was performed on microbiological data as well as patient information and the results of the gastroenterological examination. We found that the variability concerning the production of virulence factors between strains was minimal, with 96.4% of isolates being CagA-positive and 92.8% producing detectable VacA levels. In addition, high frequency of bacterial resistance was observed for metronidazole (99.1%), followed by amoxicillin (33.3%), clarithromycin (14.4%) and tetracycline (4.5%). In conclusion, this study indicated that the infection rate of H. pylori infection within the cohort in the present study was surprisingly low (36.6%). Furthermore, an average gastric pathology was observed by histological grading and bacterial isolates showed a uniform pathogenicity profile while indicating divergent antibiotic resistance rates.

Detection of FUS-1 (OXA-85), a class D beta-lactamase from Fusobacterium nucleatum subspecies Polymorphum in Nigeria.

Aims: Beta-lactamase production and subsequent resistance to β-lactam drugs has been a global concern in the treatment of Gram negative anaerobes. The aim of this study was to identify F. nucleatum strains producing Class D β-lactamase through the detection of FUS-1 (OXA-85) resistance gene. Place and Duration of Study: Department of Preventive Dentistry, Lagos University Teaching Hospital, Idi-Araba, between February 2010 and November 2010. Methodology: Twenty two oral clinical samples were obtained from patients with chronic periodontitis who admitted to previous use of amoxicillin. Antibacterial susceptibility of the bacterial isolates was determined by E-test on Brucella Blood agar. Amplification of Short Communication British Microbiology Research Journal, 3(4): 492-500, 2013 493 the bacterial DNA was carried out by PCR using F. nucleatum species-specific primer, FUS-1 specific for blaFUS-1 and strain-specific primers for subspecies nucleatum, fusiforme, polymorphum and vincentii. Results: From the 19 samples collected, F. nucleatum was isolated, and the identity of the isolates was confirmed by PCR. Four of the isolates produced similar bands with the control strain, 3 (15.7%) strains were able to produce amplication with FUS-1 primer specific for blaFUS-1 gene found in β-lactamase producing F. nucleatum subsp. polymorphum. Conclusion: This study shows the presence of class D β-lactamase producing F. nucleatum species in Nigeria.

Molecular analysis of low-level tetracycline resistance in clinical isolates of Helicobacter pylori among dyspeptic patients in South West Nigeria

OBJECTIVES The aim of this study was to determine the occurrence of 16S rRNA mutations associated with low-level tetracycline resistance in Helicobacter pylori isolates from adult dyspeptic patients in South West Nigeria. METHODS Susceptibility testing to tetracycline of 50 H. pylori isolates was performed by Etest. The 535-bp conserved region of the H. pylori tetracycline-binding site of 16S rRNA was amplified by PCR, followed by sequencing and multiple sequence alignment for all 50 clinical isolates. RESULTS Of the 50 clinical isolates examined, DNA sequence analysis revealed nucleotide substitutions in 7 isolates at positions 926-928. Of the seven isolates, two demonstrated reduced susceptibility to tetracycline with Etest minimum inhibitory concentrations (MICs) of 0.75-1.0mg/L, whilst the other five isolates were resistant with MICs of 1.5-24mg/L (resistance breakpoint >1mg/L). The two isolates with reduced susceptibility had single nucleotide substitution of A926G, whilst the five resistant isolates demonstrated double base pair substitutions of G927T/A928C and A926G/A928C and a single nucleotide substitution of A926G. CONCLUSIONS This study shows that low-level tetracycline resistance amongst H. pylori-positive dyspeptic patients is associated with reduced susceptibility and resistance to tetracycline. This is the result of 1-bp and 2-bp differences in positions 926 and 926-928, respectively, in the 16S rRNA of H. pylori.

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.

Phenotypic and molecular detection of multi-drug resistant Salmonella Enteritidis, Salmonella Typhimurium and Salmonella species in retail raw beef and chicken

Globally, Salmonella is a major cause of foodborne diseases[1,2]. The incidence of non-typhoidal Salmonella is estimated at 1.3 billion cases with annual death rate of 3 million[3]. It results in morbidity, mortality and great economic loss[4,5]. Human salmonellosis is most frequently caused by Salmonella Typhimurium (S. Typhimurium) and Salmonella Enteritidis (S. Enteritidis)[6]. Among the over 2 500 serovars identified within Salmonella enterica subspecies enterica, S. Typhimurium continues to be one of the most frequently recovered from food animals worldwide[7]. Due to its broad host range, S. Typhimurium is also one of the most common serotype isolated from human clinical cases of food-borne salmonellosis. Poor sanitary conditions have been identified to be responsible for the transmission of Salmonella spp., S. Typhimurium (group D) and S. Enteritidis (group B) in developing countries. In sub-Saharan Africa, they have been reported to be the cause of 79%–95% of all bacteriaemic non-typhoidal Salmonella infections or foodborne outbreaks[8,9], and are associated with case fatality rate of 20%– 25%[10]. Salmonella can be transmitted to humans from animals and by consuming foods from animal sources such as milk, egg, poultry meat and beef which serve as reservoirs[11,12]. During the production of meat, the major source of Salmonella contamination of carcasses is the evisceration stage in slaughter house[13]. In order to ensure food safety and for the purpose of food borne disease surveillance, foods should be examined routinely for the presence of Salmonella. Conventional typing methods such as, biotyping, serotyping and phage typing which are based on phenotypic characteristics have been used extensively for this purpose[14]. However, they are less discriminative. Molecular typing methods offer higher discrimination[14] and have been employed for identification of Salmonella spp.[9]. Studies on the molecular typing of microbial isolates have ARTICLE INFO ABSTRACT

Molecular Typing of Salmonella Species Isolated from Stool Samples

Abstract This study aimed at comparing the biochemical characterization of Salmonella spp with the molecular typing method. A total of 57 stool samples were collected from three different health institutions in Nigeria over a period of 3 months. Twenty (35%) Salmonella species consisting of 14 (70%) S. Typhi and 6 (30%) S. Choleraesuis were identified using standard methods. The isolates were then typed using randomly amplified polymorphic DNA polymerase chain reaction (RAPD-PCR) and the entero-bacteriaceae repetitive intergenic consensus PCR (ERICPCR). The ERIC-PCR differentiated the S.Typhi into 14 different sub-types with four of them (2s and 6s) and (7s and 11s) belonging to the same sub-types. The S.Choleraesuis showed no band with the ERIC-PCR while the RAPD-PCR differentiated the isolates into nine sub-types and the remaining isolates showed no visible band. The ERIC-PCR was shown to be more a discriminatory and type-able tool for Salmonella Typhi isolates.