Treatment of diarrheal infections is often challenged by development of drug resistance among the bacteria. The aim of this study was to investigate the antibacterial property of extracts of guava (Psidium guajava Linn.) leaves against diarrhea causing bacterial pathogens. Four extracts viz., ethanol, methanol, ethyl acetate and hot water extract of guava leaf were assayed for antibacterial activity against three selected bacterial pathogens along with four commercial antibiotics. The methanol extract exhibited substantial inhibitory activity (100 %) against both kinds of bacteria with a MIC of > 250 µg/ml in most cases. The ethanol extract demonstrated antibacterial activity ranging from 38 % to 65 % with the inhibition of clinical isolate of E. coli at concentrations > 500 µg/ml and both strains of V. cholerae at > 750 µg/ml respectively. The ethyl acetate and hot water extracts showed comparatively lesser response with MICs > 750 µg/ml in some cases. The commercial antibiotic Chloramphenicol exhibited absolute inhibitory action on Salmonella sp. and clinical isolate of V. cholerae. While Tetracycline and Gentamycin caused complete bactericidal action on both the strains of E. coli and V. cholerae respectively, the clinical isolate of E. coli was totally susceptible to Erythromycin. On the other hand significant percentages of resistances to these antibiotics ranging from 63 % to 88 % were also recorded. Six phytochemical compounds presumed to possess pharmacological properties were detected from methanol extract. The findings suggest that the methanol extract of guava leaf could serve as a potential source to explore promising drugs to control diarrheal infections.

Dried fishes are salted and sun dried fish products consumed by large population owing to their nutrient richness, flavor and long shelf life properties. Contamination of dried fishes by mycotoxin producing fungi pose serious threat to food safety and public health. A total of 27 samples belonging to three varieties of dried fishes collected in Chennai city, India were screened for the isolation of mycotoxin producing fungal contaminants. Mycological examination of samples revealed the prevalence of six types of fungi viz., A. parasiticus (27.27%), A. niger (22.72%), A. fumigatus (18.18%), Penicillium sp. (18.18%), Cladosporium sp. (9.09%) and Euratium sp. (4.54%). Detection using thin layer chromatography indicated that 18.18% of isolates belonging to A. parasiticus, A. fumigatus, Penicillium sp. were positive, while A. niger, Cladosporium sp., and Euratium sp.  were negative for mycotoxin production. Further to the bioassay with Artemia larvae, substantial lethality was observed with the mycotoxin of A. parasiticus (100%), followed that of by A. fumigatus and Penicillium sp. (each 50%). The HPLC studies indicated that the mycotoxin produced by A. parasiticus was Aflatoxin G2. Need for proper hygienic practices during processing and handling of dried fishes in order to avoid fungal contamination and likelihood mycotoxicosis in consumers has been suggested.