Profiling of Bacillus cereus enterotoxigenic genes from retailed foods and detection of the nhe and hbl toxins with immunological assay

Bacillus cereus produces pore-forming toxins responsible for diarrhoea; therefore, rapidly detecting these toxins in food retailed for consumption is needed. The genomic DNA of 100 B. cereus isolates recovered from some retailed foods was extracted and used as a template for enterotoxin detection. The detection of genes of non-haemolyticnonhemolytic enterotoxin (nheA, nheB, nheC), hemolysin BL (hblA, hblC, hblD), entFM, cytK and bceT by the isolates was carried out with PCR  using primers specific for the targeted genes, while the production of Nhe and Hbl enterotoxins in fifty of the randomly chosen isolates was detected with a Duopath Cereus Enterotoxin kit. Ninety-five percent of the isolates carried one or more components of the NHE complex, while 56% had one or more components of HBL. Sixteen out of the 100 isolates carried all the genes for NHE and HBL complex genes. The entFM, cytK and bceT genes were detected in 85%, 74% and 60% of B. cereus isolates, respectively. Starchy foods had the highest incidence of the HBL complex, while nheA and nheC occurred mostly in protein foods with 90% and 87% incidence, respectively. The immunological kit was able to detect the production of  nonhemolytic enterotoxin (Nhe) in all the B. cereus isolates, while 28 B. cereus isolates produced hemolysin (hbl). Nineteen isolates that carried one or more genes encoding  hbl did not produce the toxin. This study clearly showed that retailed foods sold in Ogun State, Nigeria, harbor B. cereus  enterotoxigenic genes responsible for diarrhoea. These toxins can be rapidly detected in foods using both molecular and immunological methods

Antibacterial Activity of Vanillic Acid against Staphylococcus aureus, Salmonella typhi, and Proteus mirabilis

Aim. This study investigated the efficacy of vanillic acid against selected pathogenic bacteria obtained from clinical samples. Method. The antibacterial efficacy of vanillic acid against selected pathogenic bacteria collected from clinical samples was studied using a broth macrodilution method. The minimum inhibitory concentration was determined by treating each isolate with increasing amounts of vanillic acid ranging from 150 to 2000 µg/ml. Results. The lowest inhibitory concentrations found were 600 µg/ml for Staphylococcus aureus, Proteus mirabilis, and Salmonella Typhi, and the time-kill susceptibility test also demonstrated a significant reduction in viable cells of the bacterial isolates investigated in this study. The findings of this study confirmed the antimicrobial effect of vanillic acid on bacterial growth and its activity against Staphylococcus aureus, Proteus mirabilis, and Salmonella Typhi. Conclusion. Vanillic acid may provide a solution for alternate therapeutic choices for diseases caused by Staphylococcus aureus, Proteus mirabilis, and Salmonella Typhi

Genotypic Profiling of Bacillus cereus Recovered from Some Retail Foods in Ogun State, Nigeria, and Their Phylogenetic Relationship

Identifying Bacillus cereus with conventional methods is neither specific nor rapid because of the close relatedness of the B. cereus group, hence the need for molecular methods. Genotypic profiling of B. cereus isolates from food was obtained by Random Amplified Polymorphic DNA-polymerase chain reaction (RAPD-PCR) using OPR13 primer. A dendrogram was drawn with the Numerical Taxonomy System of Statistic (NTSYS) software. Thirty of the isolates were subjected to molecular identification by 16S rDNA sequencing. The thirty sequences were deposited in GenBank for accession number. Phylogenetic relationship of the 16S rDNA sequence obtained was carried out with the Multiple Alignment using Fast Fourier Transform (MAFFT) software version 7.0. The evolutionary tree was drawn using the Molecular Evolutionary Genetics Analysis (MEGA 6) software. The dendrogram generated for the RAPD profile showed that all the strains are closely related, with a similarity coefficient of 70%. The isolates were confirmed with 16S rDNA sequencing as B. cereus. The thirty sequences deposited in GenBank were given accession numbers: KX574760–KX574769, KX610811–KX610820, MT757957-MT757963, and MT772282-MT772284. By comparing the phylogenetic relationship, eleven of the strains did not cluster with the reference strains from the GenBank but form distinct clades, which means they are likely to be of different ancestors. Conventional methods rarely differentiate bacteria of the same species into clade, neither can it describe their ancestral lineage. Therefore, it is important to employ molecular methods in identifying bacteria to give detailed information about them

Screening of Fruit and Vegetable Salads retailed in Ago-Iwoye, Ogun State for Extended- Spectrum Beta-Lactamase Producing Gram-Negative Bacteria

Extended-Spectrum Beta-Lactamase (ESBL) producing bacteria are of great concern to healthcare because of theirresistance to β-lactam antibiotics. This study aims to screen Gram-negative bacteria recovered from fruit andvegetable salads for ESBL production. The bacteria in thirty samples of fruit and vegetable salads purchased fromfood vendors were isolated and identified with standard microbiological methods. The Gram-negative bacteriarecovered were screened for ESBL production by the double disk synergy test (DDST) and brilliance ESBL agar(BEA). The total coliform counts in the fruit and vegetable salads were in the ranges 2.3 - 19.1 x 104 cfu/g and 2.8- 19.4 x 104 cfu/g respectively. Ninety-eight (98) Gram-negative bacteria were recovered from the salad samples.They were Escherichia coli (34.7%), Citrobacter freundii (21.4%), Enterobacter cloacae (10.2%), Enterobacteraerogenes (9.2%), Pseudomonas aeruginosa (9.2%). Klebsiella oxytoca (8.2%), Klebsiella pneumoniae (4.1%) andProteus mirabilis (3.1%). For ESBL production using DDST, 43. 9% (43) of the isolates were positive for the test.On the brilliance agar, 68.4% (67) showed the expected colour change as outlined by the manufacturer. However,five strains of K. oxytoca showed blue growth while sixteen of C. freundii had brown growth. ESBL-producing E.coli strains that were not detected with DDST grew on BEA. This finding showed that ESBL-producing bacteriaare present in fruit and vegetable salads retail in Ago-Iwoye, hence, there is need to take the necessary precautionsduring the preparation and storage of these food products to prevent contamination by these pathogens andsubsequent production of ESBL

Bacteriological and Phytochemical Assessment of Ficus asperifolia Linn. Infusion

Ficus asperifolia Linn. known as “Eepin” in Yoruba language, or sand paper tree, is a monoecious fig tree whose leaves, bark, seeds, and roots have been used locally in treating many infectious and noninfectious diseases. The study is aimed at investigating the bacteriological and phytochemical potential of Ficus asperifolia Linn. The roots of the plant were harvested and washed, and phytochemical analysis was carried out using standard analytical techniques. Infusion was aseptically prepared, and incubation for 24 hours and microbiological analysis were carried out using the pour plate method on Plate Count Agar (PCA) and Nutrient Agar (NA). Microorganisms were subcultured and identified using morphological and biochemical tests according to “Bergey’s Manual of Determinative Bacteriology.” Phytochemical analysis of the fresh and dry roots revealed the presence of alkaloids, cardenolides, and saponins, while anthraquinones and tannins were absent. Total heterotrophic bacteria count on PCA was 5.6×105 CFU/ml, while on NA, it was 2.3×105 CFU/ml, and four classes of bacteria were isolated including Klebsiella sp., Escherichia coli, Proteus sp., and Bacillus sp. Although the presence of medicinal phytochemicals in F. asperifolia Linn. indicates strong potentials for its use in infusions, the presence of potential pathogens found in the infusions makes it unsafe for consumption