A. A. Ogunjobi

Fermentation of yam: microbiology and sensory evaluation of cooked fermented yam tissues

The microflora of white yam ( Dioscorea rotundata L.) slices fermented anaerobically in 1.5 percent brine for five days at room temperature were studied. The hydrolysis of the carbohydrate and the subsequent conversion of sugars and minerals by the fermenting microbes contributed much to the increased microbial load especially within the first 72 hours of fermentation. The organisms implicated in the fermentation include the species of Pediococcus, Lactobacillus and Pseudomonas, Bacillus subtilis and two other Gram negative coccal cells, yet to be identified. The decrease in microbial counts at the latter stage of fermentation was attributed to the high total acidity of the medium, which was about 2.67 times the initial value of 0.027% lactic acid. Meanwhile, the lactic acid bacteria increased continuously throughout the period of fermentation.

Prevalence of tetracycline resistance genes among multi-drug resistant bacteria from selected water distribution systems in southwestern Nigeria

BackgroundAntibiotic resistance genes [ARGs] in aquatic systems have drawn increasing attention they could be transferred horizontally to pathogenic bacteria. Water treatment plants (WTPs) are intended to provide quality and widely available water to the local populace they serve. However, WTPs in developing countries may not be dependable for clean water and they could serve as points of dissemination for antibiotic resistant bacteria. Only a few studies have investigated the occurrence of ARGs among these bacteria including tetracycline resistance genes in water distribution systems in Nigeria.MethodologyMulti-drug resistant (MDR) bacteria, including resistance to tetracycline, were isolated from treated and untreated water distribution systems in southwest Nigeria. MDR bacteria were resistant to >3 classes of antibiotics based on break-point assays. Isolates were characterized using partial 16S rDNA sequencing and PCR assays for six tetracycline-resistance genes. Plasmid conjugation was evaluated using E. coli strain DH5α as the recipient strain.ResultsOut of the 105 bacteria, 85 (81 %) and 20 (19 %) were Gram- negative or Gram- positive, respectively. Twenty-nine isolates carried at least one of the targeted tetracycline resistance genes including strains of Aeromonas, Alcaligenes, Bacillus, Klebsiella, Leucobacter, Morganella, Proteus and a sequence matching a previously uncultured bacteria. Tet(A) was the most prevalent (16/29) followed by tet(E) (4/29) and tet30 (2/29). Tet(O) was not detected in any of the isolates. Tet(A) was mostly found with Alcaligenes strains (9/10) and a combination of more than one resistance gene was observed only amongst Alcaligenes strains [tet(A) + tet30 (2/10), tet(A) + tet(E) (3/10), tet(E) + tet(M) (1/10), tet(E) + tet30 (1/10)]. Tet(A) was transferred by conjugation for five Alcaligenes and two E. coli isolates.ConclusionsThis study found a high prevalence of plasmid-encoded tet(A) among Alcaligenes isolates, raising the possibility that this strain could shuttle resistance plasmids to pathogenic bacteria.

Detection of Extended Spectrum Beta-Lactamases Resistance Genes among Bacteria Isolated from Selected Drinking Water Distribution Channels in Southwestern Nigeria

Extended Spectrum Beta-Lactamases (ESBL) provide high level resistance to beta-lactam antibiotics among bacteria. In this study, previously described multidrug resistant bacteria from raw, treated, and municipal taps of DWDS from selected dams in southwestern Nigeria were assessed for the presence of ESBL resistance genes which include bla TEM, bla SHV, and bla CTX by PCR amplification. A total of 164 bacteria spread across treated (33), raw (66), and municipal taps (68), belonging to α-Proteobacteria, β-Proteobacteria, γ-Proteobacteria, Flavobacteriia, Bacilli, and Actinobacteria group, were selected for this study. Among these bacteria, the most commonly observed resistance was for ampicillin and amoxicillin/clavulanic acid (61 isolates). Sixty-one isolates carried at least one of the targeted ESBL genes with bla TEM being the most abundant (50/61) and bla CTX being detected least (3/61). Klebsiella was the most frequently identified genus (18.03%) to harbour ESBL gene followed by Proteus (14.75%). Moreover, combinations of two ESBL genes, bla SHV + bla TEM or bla CTX + bla TEM, were observed in 11 and 1 isolate, respectively. In conclusion, classic bla TEM ESBL gene was present in multiple bacterial strains that were isolated from DWDS sources in Nigeria. These environments may serve as foci exchange of genetic traits in a diversity of Gram-negative bacteria.

Comparative analysis of genetic variation among Xanthomonas axonopodis pv manihotis isolated from the western states of Nigeria using RAPD and AFLP

Xanthomonas axonopodis pv manihotis is the causal agent of cassava bacterial blight (CBB) worldwide. CBB disease is a major constraint to cassava cultivation, and losses can be extremely severe in regions where highly susceptible cultivars are grown. To develop an efficient disease management policy, the genetic diversity of the pathogens population must be known. There is dearth of information on the genetic diversity of X. axonopodis pv manihotis population in Nigeria. We used RAPD (random amplified polymorphic DNA) and AFLP (amplified fragment length polymorphism), a PCR-based technique, to characterize the X. axonopodis pv manihotis isolates from the western States of Nigeria. Thirteen strains Xam and 2 reference strains were tested with eight primers combination of AFLP and 4 RAPD primers. RAPD amplified DNA fragment data showed four major clusters at 80 % similarity coefficient level and two strains were not clustered by this analysis. Strains Kwa76A and Ond48A were also separated in the principal component analysis of the same data. Numerical analysis differentiated the AFLP patterns into four distinct clusters and grouped two strains separately at 66 % similarity. PCA assembly grouped the bacterial strains into 4 and one of the strains was singled out from the others. The two DNA analyses techniques seem to be complimentary to one another and informative on the genomic structure of Xam population in Western Nigeria. The genetic analysis presented here contributes to understanding of the Xam population structure in Western Nigeria.

Characterization of Integrons and Sulfonamide Resistance Genes among Bacteria from Drinking Water Distribution Systems in Southwestern Nigeria

Background: The emergence of antibiotic resistance among pathogenic bacteria in clinical and environmental settings is a global problem. Many antibiotic resistance genes are located on mobile genetic elements such as plasmids and integrons, enabling their transfer among a variety of bacterial species. Water distribution systems may be reservoirs for the spread of antibiotic resistance. Materials and Methods: Bacteria isolated from raw, treated, and municipal tap water samples from selected water distribution systems in south-western Nigeria were investigated using the point inoculation method with seeded antibiotics, PCR amplification, and sequencing for the determination of bacterial resistance profiles and class 1/2 integrase genes and gene cassettes, respectively. Results:sul1,sul2, and sul3 were detected in 21.6, 27.8, and 0% of the isolates, respectively (n = 162). Class 1 and class 2 integrons were detected in 21.42 and 3.6% of the isolates, respectively (n = 168). Genes encoding resistance to aminoglycosides (aadA2, aadA1, and aadB), trimethoprim (dfrA15, dfr7, and dfrA1), and sulfonamide (sul1) were detected among bacteria with class 1 integrons, while genes that encodes resistance to strepthothricin (sat2) and trimethoprim (dfrA15) were detected among bacteria with class 2 integrons. Conclusions: Bacteria from these water samples are a potential reservoir of multidrug-resistant traits including sul genes and mobile resistance elements, i.e. the integrase gene.

Indoor airborne microbial burden and risk of acute respiratory infections among children under five in Ibadan, Nigeria

Acute respiratory infection is the fourth major cause of morbidity and mortality among under-five children globally. However, the profile of microbial burden that could contribute to these infections among under-five children in the indoor environments has not been extensively studied particularly in developing countries like Nigeria. This study was designed to determine the burden of airborne microbes in indoor environment that predispose under-five children to acute respiratory infections. A prospective case–control design was employed for this study. Two hundred and twenty under-five children each with acute respiratory infection (cases) and without acute respiratory infection (controls) were selected from children visiting Oni-memorial Children Hospital and University College Hospital, Ibadan. A follow-up of 66 consented cases and controls each was carried out to assess the burden of indoor airborne microbes using a non-volumetric method, and the total counts per cubic metre were compared with the American Industrial Hygiene Association guideline. Data were analysed using descriptive statistics, t-test and Spearman’s rank correlation. Mean indoor total bacterial count for cases (9.6 × 102 cfu/m3) was significantly higher than the permissible limit recommended by the American Industrial Hygiene Association (≤500 cfu/m3) as compared to controls (3.5 × 102 cfu/m3) (p < 0.05). Educating mothers of under-five children on improved ventilation, good housing and indoor sanitary practices to reduce indoor microbial load is therefore advocated.

Evaluation of Resistance Pattern and Plasmid Profile of Staphylococcus Species Isolated from Clinical and Community Samples in Ibadan South-West, Nigeria

Aims: Staphylococcus species have been a major human pathogen of public health importance globally. This study was designed to evaluate the resistance pattern and plasmid profile of Staphylococcus species isolated from clinical and community settings. Methodology: Staphylococcus species from clinical (55) and community (53) which were previously isolated in University of Ibadan and her teaching hospital and identified as S. epidermidis (92.6%), S. aureus (6.5%) and S. xylosus (0.9%) were used. The antibiogram and plasmid profiles were determined by standard procedures. Original Research Article Ezeamagu et al.; JAMB, 3(3): 1-9, 2017; Article no.JAMB.33655 2 Results: In clinical isolates of S. epidermidis, 30.9, 34.5, 40.0, 41.8, 60.0, 76.4, and 89.1% were resistant to chloramphenicol (CHL), streptomycin (STR), erythromycin (ERY), gentamycin (GEN), tetracycline (TET), cotrimoxazole (COT), and cloxacillin (CXC) respectively. Correspondingly, in community isolates of S. epidermidis, 28.3, 32.1, 50.9, 26.4, 58.5, 90.6 and 92.5% were resistant to these antibiotics. The only clinical S. xylosus isolated was resistant to all the antibiotics except CHL and STR. In the clinical isolates of S. aureus, 5.5, 5.5, 7.3, 7.3, 7.3, 9.1 and 9.1% were resistant to ERY, CHL, STR, GEN, TET, COT and CXC respectively. In community isolates, only one S. aureus was resistant to COT, CHL, ERY, GEN and STR while two were resistant to CXC. Plasmid profiling showed that 33/35 (94.3%) of clinical and 17/19 (89.5%) of community isolates had plasmid of size 23.13 kb. Conclusion: The increasing resistance and similarity of plasmid profile of the community isolates to clinical isolates call for urgent establishment of antibiotic surveillance system to minimize the emergence of drug resistance pathogens in the community.