Antimicrobial properties of lactic acid bacteria and yeast-LAB cultures isolated from traditional fermented milk against pathogenic Escherichia coli and Salmonella enteritidis strains.

The survival and growth of Escherichia coli 3339 and Salmonella enteritidis 949575 isolated from human clinical samples, in milk fermented with lactic acid bacteria (LAB) and yeast strains previously isolated from Zimbabwean naturally fermented milk (NFM) was studied. The LAB starter cultures used were Lactococcus lactis subsp. lactis biovar. diacetylactis C1 alone (C1) or in combination with Candida kefyr 23 (C1/23), L. lactis subsp. lactis Lc261 alone (LC261) or in combination with C. kefyr 23 (Lc261/23). The growth of the same pathogens in milk fermented with a commercial DL culture (CH-N 22) and spontaneously fermented raw milk was also monitored. The C1 and C1/23 cultures significantly (P<0.05) inhibited the growth of both pathogens. When inoculated at the beginning of the fermentation, both E. coli 3339 and S. enteritidis 949575 counts were significantly (P<0.05) reduced by about two log cycles in C1 and C1/23 cultured milk. However, in naturally fermented milk and the DL cultured milk, both E. coli 3339 and S. enteritidis 949575 grew and reached high populations of about 9 and 8.8 log cfu ml(-1), respectively, after 18 h. When E. coli 3339 was inoculated into previously fermented milk, the viable counts were significantly (P<0.05) reduced in the presence of C1 and C1/23 from 7 log cfu ml(-1) to 3 log cfu ml(-1) after 48 h. S. enteritidis 949575 could not be recovered from these cultures after 48 h. The addition of the yeast did not enhance or diminish the inhibitory capacity of the LAB cultures. The pathogens survived in high numbers when inoculated into pre-fermented NFM and the commercial DL- (CH-N 22) cultured milk. The C1 strain, therefore, offered the best protection against the pathogens. Its inhibitory effect was mainly related to fast acid production.

Awareness of the risks of HIV infection by Zimbabwean urban and rural high school attendees.

OBJECTIVES: The purpose of this report was to investigate the awareness by high school attendees of risky behaviour likely to lead to sexually transmitted infections (STIs) including HIV/AIDS and to assess their preparedness to prevent or obviate the consequences. DESIGN: Cross sectional study. SETTINGS: A small town located 100 km south of the Zimbabwean capital, Harare and in communal and commercial farming areas within a 50 km radius of the town. METHODS: With the permission of school authorities, a group of second year medical students from the University of Zimbabwe on rural attachment administered an anonymous questionnaire to teenagers attending four high schools in the study area. Specific questions to determine whether the teenagers were sexually active and if they used any protection during sex were incorporated into a general and environmental health questionnaire. RESULTS: A total of 241 teenagers, 153 boys and 89 girls from all four schools completed the questionnaire. The percentages of sexually active boys (48%) and girls (49%) were similar. The majority had heterosexual preferences, 4.6% boys were homosexual. Half (50%) of the 16 year old pupils were sexually active. There were more urban than rural school attendees who reported personal knowledge of someone with HIV or AIDS. Condom use was low. CONCLUSION: We found that half of the 16 to 19 year old students were sexually active. Rural school attendees were more likely to be sexually active and less likely to practice safe sex. We conclude that the risk of sexually transmitted diseases (including HIV) amongst these teenagers is significant and recommend that, there is a need to design a group targeted awareness programme in order to obviate sexually transmitted diseases including HIV.