This present work was designed to investigate the effect of different extraction solvents on the antimicrobial activity of Psidium guajava leaves against some multidrug resistant bacteria in nosocomial infections. The MDR isolates such as Pseudomonas aeruginosa, Escherichia coli, Staphylococcus epidermidis, Proteus mirabilis, Staphylococcus saprophyticus and Bacillus cereus were obtained from Microbiology department culture collection of Department of Microbiology University of Ibadan Nigeria and their identities reconfirmed using biochemical methods. The antimicrobial activities of the different solvent extracts were tested using agar well diffusion method while the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of the extracts were monitored using the double fold dilution method. The results reconfirmed the identities of the bacteria as Pseudomonas aeruginosa, Escherichia coli, Staphylococcus epidermidis, Proteus mirabilis, Staphylococcus saprophyticus and Bacillus cereus. Methanol extracts at a concentration of 160 mg/ml showed the highest inhibition zone of 10.0±0.1mm followed by ethyl acetate extract with 8.0±0.6mm inhibition zone against E.coli which were significantly different (P<0.05) while Nhexane, cold and hot water showed zero inhibition zones. Ofloxacin and DMSO. showed 20.0±0.and 0.00 mm inhibition zones respectively. This trend was observed at all the other concentrations. Methanol and ethyl acetate had MIC of 40.0 mg/ml for E. coli, S. saprophyticus, P.aeruginosa and B. cereus and they showed MBC of 80.0mg/ml for E. coli, S. saprophyticus, P.aeruginosa and B. cereus and MBC of 40.0 mg/ml for S. Epidermidis. Methanol and ethyl acetate extracts could be employed in the treatment of bacterial infections caused by MDR bacteria.Contribution/Originality: The paper's primary contribution is finding that Psidium guajava (guava) leaf extracts can be used for the treatment of some multi-drug resistant bacteria implicated in nosocomial infections.Methanol and ethyl acetate extracts of the leaves possess the greatest antimicrobial activity due to the high sensitivity of the MDR organisms.

This study investigated the beneficial effects of fermenting microorganisms as well as the presence of aflatoxins in milled flour samples. Thermotolerance, pH tolerance, phenol tolerance, temperature sensitivity, in-vitro antimicrobial potentials of lactic acid bacteria (LAB) isolates and aflatoxin detection in the milled flour sample were analyzed. LAB isolates were identified and characterized as Lactobacillus species using standard procedures. Probiotic properties and antimicrobial activity of LAB isolates were investigated using standard methods. In addition, quantitative and qualitative detection of aflatoxins in the milled flour samples were also studied. The results showed that all the LAB isolates were Lactobacillus species which survived in high temperature range of 50 0 C-60 0 C, acidic pH (pH 2, 3, 4 and 5), phenol tolerance (0.1%, 0.2%, 0.3% and 0.4%). In -vitro antimicrobial properties of the LAB species (PSEO1 and PSEO4) showed that they were able to inhibit the growth of Escherichia coli(ATCC 43816) and Klebsiella pneumoniae(25922) with the corresponding zones of inhibition: 25mm and 20 mm. Due to the effect of storage time (6 months), yam and plantain flour samples moisture content yielded 9.50% and 9.20% with the corresponding total number of aflatoxins: 859.3 and 899.0. In conclusion, LAB species isolated from yam and plantain flour samples have probiotic potentials. Moreover, the longer the storage time, the higher the number of aflatoxins. Thus, they should be consumed within the shortest time possible to avoid caking and moisture accumulation which tends to decrease the number of beneficial microbes present in them. Contribution/Originality:This study documents the inherent probiotic bacteria isolated from yam and plantain flour. These microorganisms enhance the improvement of the gastrointestinal tract. Therefore, storing these food products in a humid-free environment will prevent moisture accumulation and aflatoxin contamination. This in turn reduces the risk of food-borne intoxications. INTRODUCTIONWhite yam (Dioscorea rotundata) and plantain (Musa parasidiaca) are good sources of carbohydrate, protein and dietary fibre (Akissoe, Joseph, Christian, & Nago, 2003;Jonathan & Olowolafe, 2001). These food products are undoubtedly important staple foods in that they contribute substantially to the calories consumed by humans. But,