Colorimetric assay for the in vitro evaluation of Saprolegnia biofilm inhibitors.

A quantitative and reproducible 96-well microtiter method that is easily adaptable for the screening of Saprolegnia biofilm inhibitors is described. As opposed to other methods previously developed for the screening of Saprolegnia inhibitors on spore germination or mycelial growth, this technique is of particular significance as it investigates potential inhibitors against surface-attached mycelial mats of Saprolegnia spp. (biofilm). In this study, we have investigated the effects of propionic acid (PPA) on reducing the viability of induced Saprolegnia biofilms using colorimetric MTS assay based on the reduction of tetrazolium salts. Viability of Saprolegnia hyphae in treated biofilms was reduced significantly following treatment with different PPA concentrations. The effect was enhanced after combining each of the tested PPA concentrations with 500 mg/L of boric acid (BA). However, the percentage of non-viable hyphae was still higher in 200 mg L-1 bronopol-treated biofilms (positive control) following 6- and 12-hr exposure. Similar results were observed using other recently described fluorescence-based assays for viability.

Antimicrobial Resistant Enteropathogenic Escherichia coli and Salmonella spp. in Houseflies Infesting Fish in Food Markets in Zambia.

Diarrhea is one of the most common diseases and is a leading cause of death in developing countries. This is often caused by contaminated food. Poor food hygiene standards are exacerbated by the presence of flies which can transmit a variety of infectious microorganisms, particularly through animal source foods. This fact becomes especially important in developing countries like Zambia, where fish is a highly valued source of protein. Our interest in this study was to identify if the flies that beset food markets in Zambia carry important pathogenic bacteria on their bodies, and subsequently if these bacteria carry resistance genes to commonly used antibiotics, which would indicate problems in eradicating these pathogens. The present study took into account fish vendors' and consumers' perception of flies and interest in interventions to reduce their numbers. We conducted semi-structured interviews with (1) traders (comprised of randomly selected males and females) and (2) consumers (including randomly selected males and females). Thereafter, we collected flies found on fish in markets in Mongu and Lusaka districts of Zambia. For the entire study, a total of 418 fly samples were analyzed in the laboratory and Salmonella spp. and enteropathogenic Escherichia coli were isolated from the flies. Further laboratory screening revealed that overall, 17.2% (72/418) (95% CI; 43.2%-65.5%) of total samples analyzed contained Extended-Spectrum Beta-Lactamase (ESBL)-producing E. coli. These significant findings call for a strengthening of the antibiotic administering policy in Zambia and the development of sustainable interventions to reduce fly numbers in food markets and improve food safety and hygiene.

Microbial Contamination and Hygiene of Fresh Cow's Milk Produced by Smallholders in Western Zambia.

A field study was performed to assess safety of smallholder fresh cow's milk around Mongu, Western Province, Zambia. This involved observation and sampling of milk along the value chain from milking to point-of-sale and storage. Samples were collected from 86 cows, from 9 farmers, selling through two dairy cooperatives, with additional samples from informal markets. Production was very low; around one litre/day/cow and 10 L/day/herd. The milk was typically transported by bicycle in high ambient temperatures without refrigeration until reaching the point-of-sale (journey times of 30-120 min), where it was sold without pasteurisation despite milk-borne zoonoses being endemic (bovine tuberculosis (bTB) and Brucellosis). Although microbiological contamination was initially low, with geometric mean total bacterial count (TBC) of 425 cfu/mL (cfu = colony forming units) upon arrival at point-of-sale, poor hygiene led to high bacterial loads later on (geometric mean TBC > 600,000 cfu/mL after two days refrigeration), with almost all samples culture positive for Staphylococcus aureus and Escherichia coli. After milking, milk was kept for 100-223 min at temperatures favouring microbial growth (median 34 °C) and sold without a microbial kill step. In this situation limited variation in observed standards of milk hygiene had no significant effect on milk end-product bacterial counts. Options for refrigerated transport are limited. Pasteurisation at the cooperative should be investigated, as this would largely remove pathogenic microbes present in the milk whether resulting from cattle infection or poor hygiene during milking and transportation. As milk is also purchased directly from producers, on-farm milk heating options should also be assessed. Smallholders may benefit from access to national markets by providing milk to large dairies, which have systems for ensuring safety. However, this requires significant investment and an increased and more consistent supply of milk; and many consumers, unable to afford milk sold through formal sectors, would not benefit.

Field observations of fish species susceptible to epizootic ulcerative syndrome in the Zambezi River basin in Sesheke District of Zambia.

A field investigation was conducted in the Sesheke District of Zambia along the Zambezi River to determine the fish species susceptible to epizootic ulcerative syndrome (EUS), a newly confirmed disease in Southern Africa. A total of 2,132 fishes were inspected for gross EUS-like lesions, of which 188 (8.82%; 95% CI=7.67-10.1%) were found with typical characteristic lesions of EUS. Of these 188 samples, 156 were found to have mycotic granulomas on histopathological analysis, representing 83.0% (95% CI=76.7-87.9%) of the initially identified in the laboratory through gross examination. The following 16 species of fish were examined and found with EUS lesions; Clarias ngamensis, Clarias gariepinus, Barbus poechii, Tilapia sparrmanii, Serranochromis angusticeps, Brycinus lateralis, Micralestes acutidens, Sargochromis carlottae, Hydrocynus vittatus, Phryngochromis acuticeps, Schilbe intermedius, Hepsetus odoe, Labeo lunatus, Oreochromis andersonii, Barbus unitaeniatus, and Barbus paludinosus. T. sparrmanii did not show any lesions, while the Clarias species were found to be the most afflicted with EUS. These results could be useful to fish farmers and organizations interested in improving aquaculture in the area.

A rapid situation assessment of sexual risk behaviour of alcohol users in Lagos, Nigeria.

BACKGROUND: National sentinel surveys of HIV/AIDS among pregnant women in Nigeria have shown steady rise in prevalence from 1991 (1.8%) to 2001 (5.8%), which may reflect the pattern in the adult population in the country. The roles of known potential risk factors of the HIV/AIDS scourge in Nigeria deserve elucidation. This work aims to study the relationship between alcohol use and sexual risk behaviour. PATIENTS AND METHODS: Rapid assessment technique involving qualitative and quantitative methods was employed. A multi-site design which made it possible to compare samples recruited in high and low density settings was used. RESULTS: One hundred and nine of the alcohol users were recruited in the Low Density Area (LDA), while 130 were recruited in the High Density Area (HDA). In the HDA, 49 (53%) of the beer users used alcohol before sex either most or all of the time 21 (22.6%), or occasionally 28 (29.1%). Unlike the beer users less than half, 8 (42.1%), of Palm wine drinkers drank alcohol before sex. Beer users in the HDA used beer after sex with casual partners significantly more than the Palm wine drinkers (P = 0.036). Alcohol users in the LDA were more inclined to casual sex and they (54, 56.8%) believed that it had some or major role in their desire as well as performance of sex compared with users in the HDA (P = 0.005). CONCLUSION: Irrespective of their socioeconomic class, ethnicity, religion and educational attainment alcohol users in the country indulge in high risk sexual behaviours that predispose them to infection with HIV and other sexually transmitted diseases.