The characterisation of 24 lactic acid bacteria (LAB) isolates from Nigerian traditional fermented dairy foods, including some cow's intestine isolates, was conducted in order to select isolates for potential use as probiotics. LAB isolates were identified by partial sequencing the 16S rRNA gene as belonging to the species Lactobacillus paracasei, Lactobacillus brevis and mainly Weissella confusa. At the end of a characterisation process, 2 L. paracasei and 2 W. confusa isolates were selected, and their resistance to a simulated gastrointestinal digestion and their ability to adhere to eukaryotic cell lines were assessed. The survival to the simulated gastrointestinal passage was higher when bacterial suspensions were made in skimmed milk (2.0±0.8 log units reduction) or at the simulated gastric juice pH 3 (2.7±0.9 log units reduction) than at pH 2.0 (5.5±0.7 log units reduction). Adhesion of LAB to both intestinal and vaginal epithelial models was comparable or higher than that of the reference Lactobacillus rhamnosus GG. However, some of the isolates increased the adhesion of the pathogen Escherichia coli LMG2092 to HT-29 and HeLa monolayers. Overall, isolates L. paracasei UI14 and W. confusa UI7 are good candidates for further studying potential benefits that support their use as probiotics. This is one of the few articles reporting the characterisation and the probiotic potential of Weissella, although more studies are needed in order to establish their safety for potential probiotic applications.

BackgroundNon typhoidal salmonellosis is one of the neglected zoonoses in most African countries. The use of sub-therapeutic doses of antibiotics as animal growth promoter enhances the emergence and dissemination of antimicrobial resistance in bacteria with food animal reservoirs and may also results in antibiotics residue in animal products. One promising alternative to antibiotics in animal feed is Lactic Acid Bacteria (LAB) as probiotics. This study was carried out to determine the anti-salmonella activities and suitability of LAB isolated from cattle faeces in Nigeria as potential probiotics in cattle feed.MethodThe test Salmonella enterica spp strains and LAB were isolated from cattle faeces and identified by MALDI-TOF MS and partial sequencing of 16S rRNA genes respectively. The anti-salmonella activities of the isolated LAB in co-culture, cell-free supernatant, inhibition of growth by viable LAB cells and quantification of organic acids were determined by standard techniques. The ability of the LAB strains to withstand gastric conditions, antibiotic susceptibility and their haemolytic ability on blood agar were also determined.ResultsA total of 88 LAB belonging to 15 species were isolated and identified from cattle faeces. The most abundant species were Streptococcus infantarius (26), Enterococcus hirae (12), Lactobacillus amylovorus (10), Lactobacillus mucosae (10) and Lactobacillus ingluviei (9). Most of the LAB strains showed good anti-salmonella activities against the test Salmonella enterica spp. with 2 Lactobacillus strains; Lactobacillus amylovorus C94 and Lactobacillus salivarius C86 exhibiting remarkable anti-salmonella activities with total inhibition of Salmonella spp after 18 hours of co-incubation. The selected strains were able to survive simultaneous growth at pH 3 and 7% bile concentration and are non hemolytic.ConclusionThis study reports the vast diversity of culturable LAB in cattle faeces from Nigeria and their putative in-vitro antibacterial activity against Salmonella enterica spp isolated from cattle. Lactobacillus amylovorus C94 and Lactobacillus salivarius C86 demonstrated promising probiotic potentials in-vitro and will be further tested in-vivo in animal field trial.

No abstract

Thirty K. pneumoniae produced multiple beta-lactamases, with 57% producing CTX-M enzymes. This is the first characterization of CTX-M-15-positive K. pneumoniae in Western Africa.

BackgroundMultidrug resistant Pseudomonas aeruginosa harbours integrons and other mobile genetic elements such as plasmids and transposons, which easily disseminate antibiotic resistance genes among clinical strains of P. aeruginosa.MethodologyPlasmid extraction of 54 clinical isolates of P. aeruginosa was carried out by alkaline lysis method; and plasmid size estimation was done by using E. coli V517 standard plasmid marker. Fifty-four clinical strains of P. aeruginosa were isolated from 5 hospitals in 3 Southwestern states of Nigeria between March and September 2010. Plasmid extraction of isolates was carried out by alkaline lysis method; and plasmid size estimation was done by using E. coli V517 standard plasmid marker. PCR amplification for the 3 classes of resistance integrons, and gene cassette characterization were carried out using specific primers and by sequencing of PCR products. Conjugal mating of the integron positive P. aeruginosa strains with E. coli DH5α was performed to demonstrate transferability of integrons and gene cassettes.ResultAgarose gel electrophoresis of plasmid DNA revealed that all the 54 P. aeruginosa harboured 1–4 plasmids with sizes ranging from 2.2 – >58 kb. Class 1 integron was identified in 31 (57%) strains; but none of them carried class 2 and class 3 integrons. High prevalence of aadA gene conferring resistance to streptomycin/spectinomycin was detected in the strains positive for class 1 integron. Sequencing of the 1.6 kb and 1.2 kb amplified band of gene cassettes revealed the presence of aadA6-orfD and aadA13 respectively.ConclusionThis study demonstrates the presence of plasmids and integrons harbouring resistance gene cassettes, which may collectively constitute an efficient system for dissemination of resistance genes in P. aeruginosa. Disturbingly, the rapid and unabated spread of class 1 integron-associated multidrug resistant P. aeruginosa in Southwest Nigeria may greatly hamper successful treatment of infections caused by such strains. This necessitates the establishment of functional antimicrobial resistance surveillance programmes in Nigeria.