Microbiology

Serotype G9 strains have been detected sporadically and in localized outbreaks in various African countries, including South Africa, Botswana, Malawi, Kenya, Cameroon, Nigeria, Ghana, Guinea-Bissau, Libya, and Mauritius. Serotype G9 strains were analyzed to investigate genogroup characteristics, including subgroup specificity, electropherotype, and P and G genotypes. In addition, the antigenic composition of the South African G9 strains was assessed. African G9 strains were associated with both DS-1-like characteristics and Wa-like characteristics, indicating the predisposition of G9 strains to frequently reassort. Despite these reassortment events, serotype G9 strains appear to maintain antigenic character in the outer capsid protein, as evident with the reaction of the South African G9 strains with the G9-specific monoclonal antibody F45:1. Phylogenetic analysis clustered African G9 strains geographically, regardless of genogroup characteristics, into 1 lineage (IIId). Two groups ...

Background. Data regarding the prevalence and molecular epidemiology of rotavirus infection in rural areas of Africa are limited. In this study the prevalence and genetic diversity of rotaviruses in a rural South African setting were investigated.

Detection and molecular characterisation of a group 16SrIX phytoplasma infecting citrus (Citrus sinensis and C. limon), coffee (Coffea arabica), periwinkle (Catharanthus roseus), and tabebuia (Tabebuia heterophylla) in Puerto Rico Abstract Few studies have determined the presence of phytoplasmas in important crops in Puerto Rico. Disease symptoms resembling those caused by phytoplasmas were observed in pigeon pea (Cajanus cajan), periwinkle (Catharanthus roseus), tabebuia (Tabebuia heterophylla), Spanish lime (Melicoccus bijugatus), ixora (Ixora coccinea), mango (Mangifera indica), cactus (Opuntia spp.), citrus trees (Citrus spp.), and coffee (Coffea arabica). Sixty-two samples from these species were tested using conventional PCR to amplify the 16S rRNA and ribosomal protein genes (rpIV-rpsC). Fifty-one percent of the tested samples (corresponding to periwinkle, pigeon pea, citrus, coffee and tabebuia) were positive for phytoplasmas, with amplicons of 0.8 (16S rRNA gene) and 1.2 kb (rpIV-rpsC genes), depending upon primers used in PCRs. For both genetic loci, DNA sequences showed 99 % identity with pigeon pea witches' broom phytoplasma (PPWB). Due to the lack of studies of potential insect vectors, common Auchenorrhyncha species were sweep-collected from pigeon pea and citrus and tested for phytoplasma. Of nine insect genera collected, Empoasca kraemeri (Cicadellidae), Melormenis antillarum (Flatidae), and Colpoptera maculifrons (Issidae) were positive for PPWB based on results from conventional PCR and DNA sequence analysis. The findings indicate that these insects fed upon the aforementioned plant species, ingesting contents of phloem, and may act as potential phytoplasma vectors in the field. These are first reports of PPWB phytoplasma infections in citrus species (C. sinensis and C. limon), coffee, periwinkle and tabebuia, and in insects (E. kraemeri, M. antillarum and C. maculifrons) for Puerto Rico.

Bacterial contaminants of Vhuswa--a traditional maize-based weaning food, and domestic drinking-water stored in impoverished rural households in Venda of Limpopo province, South Africa, were determined. One hundred and twenty-five samples of Vhuswa fed to children aged less than five years were assessed for Escherichia coli, Campylobacter jejuni, Salmonella, and Shigella. The microbiological quality of 125 drinking-water samples was also evaluated using total coliforms, faecal coliforms, and faecal streptococci as indicators. The frequency of isolation of E. coli, Salmonella, Shigella, and C. jejuni from the Vhuswa samples was 70%, 5%, 5%, and 2% respectively. The geometric mean counts of total coliforms, faecal coliforms, and faecal streptococci in tap-water stored in household containers ranged from 4.9x10(2) to 5.8x10(3) cfu 100 mL(-1), 2.6x10(2) to 3.7x10(3) cfu 100 mL(-1), and 3.1x10(3) to 5.8x10(3) cfu 100 mL(-1) respectively, and for stored spring water it was 5.1x10(3) cfu 1...

The volatile oil of Lippia javanica was prepared by hydrodistillation of leaves, flowers and stems, and characterized by GC-MS. The major component was 3-methyl-6-(1-methylethylidene)-cyclohex-2-en-1-one. The oil was tested for antimicrobial activity on cultures of Escherichia coli, Bacillus subtilis and Staphylococcus aureus, and found to inhibit E. coli and S. aureus at 1% dilution. The oil was also active against Plasmodium falciparum in micromolar concentrations.

A study has been done in Luvuvhu Catchment to develop a framework for effective community participation in water quality monitoring and management. Community participation and involvement in development has since the 1970s gathered momentum among the non-governmental organisations (NGOs) fraternity but has never gained clear status with Governments world over. In South Africa the policy and legal frameworks for community consultation, involvement and participation are clearly spelt out on paper starting with the country's constitution. The division of the country into Water Management Areas (WMA) and the formation of Catchment Management Agencies (CMA), Water User Associations (WUAs) for example, was meant to increase participation of stakeholders including communities in the management of water resources. These efforts have not translated into effective participation by local communities in the management of water resources because there is no link between the national water quality management frameworks and community based development structures.

Rotavirus infection is associated with acute infantile gastroenteritis in infants and young children globally. In South Africa, rotavirus infection has been shown to be associated with approximately one-quarter of all diarrhoeal admissions to hospital. Rotavirus infection predominantly occurs in infants less than 12 months of age (75%) and has a peak of shedding during the cooler, drier months of the year. A secondary peak during the spring has been observed. Multiple infections with rotavirus and at least one other microbial agent are common. The circulating VP7 serotypes and VP4 genotypes have been determined in various regions of South Africa and show a geographic specific distribution. A decade previously, P[8]G1 or G4 strains predominated, and P[4]G2 strains occurred in an epidemic pattern in one region. More recently, rotavirus strains with P[6] genotype have become common and novel VP7/VP4 genotype combinations are occurring across the country. G9 strains have been reported from Cape Town to Vendaland. The circulating rotavirus types observed in this study add to the knowledge of the natural history of rotavirus infection and provide the groundwork to consider future vaccine strategies.

The microbial quality of several, untreated surface water sources, used by rural communities in the Venda region of South Africa, was assessed to determine its safety for human consumption and to highlight the possible occurrence of water-borne diseases. The water sources studied were six sampling points on the Levubu River, Vuwani, Mutale, Ngwedi, Tshinane, Makonde, Mutshindudi and Mudaswali Rivers. Heterotrophic plate counts, faecal and total coliforms, enterococci and somatic coliphage counts were performed according to standard methods to determine the microbiological quality of the water sources. The presence of enteric pathogens such as Salmonella, Shigella, Campylobacter, Plesiomonas, Aeromonas and Vibrio was also determined.

The Venda region of South Africa is predominantly rural and residents rely on untreated water sources for daily water needs. The physico-chemical quality of these water sources including antibiotic susceptibilities of enteric bacterial isolates which would guide clinicians in the empiric management of diarrhoea have received cursory attention. This study therefore sought to document the physico-chemical parameters and antibiograms of bacterial isolates from water sources in order to determine the safety for human consumption and to provide updated antibiotic data for empiric treatment of patients. Water samples were obtained on a weekly basis from Ngwedi, Mutale, Tshinane, Mutshindudi and Mudaswali Rivers and Makonde, Mudaswali and Thamathama Fountains between August 2000 and July 2002. Physico-chemical parameters such as turbidity, temperature, pH, lead, fluoride, cyanide, iron, sulphate, chromate and nitrate were determined. Antibiograms of bacterial isolates were ascertained using the disk diffusion method.

Molecular techniques were used to characterise clinical and environmental isolates of non-typhoidal Salmonella obtained from environmental (water and food) and clinical (stool) specimens in rural Venda communities, Limpopo Province of South Africa. Results obtained revealed that out of a total of 457 environmental and clinical isolates examined for the prevalence of Salmonella isolates, 293 (64%) were positive. Results further revealed that 266 (75%) out of 375 environmental samples screened and 27 (27%) of the clinical stool specimens were positive for Salmonella respectively. Phenotypic differentiation indicated that all 27 (100%) clinical specimens and 44 (15%) of the environmental isolates were identified as Salmonella subspecies I (human associated isolates) and a total of 222 (76%) as Salmonella subspecies II-VI (environmentally associated isolates) which are rarely isolated from humans. Only strains of Salmonella subspecies I were subjected to molecular characterization using PCR techniques to rapidly identify Salmonella typhimurium and Salmonella enteriditis. Sixteen (36%) environmental Salmonella isolates, 26 (96%) of clinical isolates and a Salmonella typhimurium reference strain gave a 559 bp amplified fragment with the Fli l5-Tym primer set only and did not a 488 bp amplified fragment with the AO58-AO1 primer set. These isolates were classified as Salmonella typhimurium. Only one clinical isolate (4%) and a Salmonella enteriditis reference strain produced a 488 bp fragment with the AO58-AO1 primer set and was classified as Salmonella enteriditis. No 559 or 488 bp amplified products were found for the remaining 28 (39%) environmental Salmonella subspecies I isolates.

To determine the effectiveness of ceramic filters in reducing diarrhea, we conducted a randomized con- trolled trial in Zimbabwe and South Africa, in which 61 of 115 households received ceramic filters. Incidence of non-bloody and bloody diarrhea was recorded daily over 6 months using pictorial diaries for children 24-36 months of age. Poisson regression was used to compare incidence rates

The study was conducted to assess the effect of definition of episode on diarrhoeal morbidity and to develop a means of adjusting estimates of morbidity for the definition of episode used. This paper reports on a cohort study of 374 children, aged 9-32 months, in three African countries, which recorded frequency and consistency of stool over a seven-month period. Different definitions of episode were applied to these data to assess their effect on annualized diarrhoeal morbidity. Adjustment factors were then derived that corrected morbidity for non-standard definitions of episode. Applying non-standard definitions of episode gave estimates of an annualized number of episodes between 38% and 137% of the internationally-accepted definition. Researchers should be encouraged to use the standard definition of episode of diarrhoea and to use appropriate field protocols. Where this is not possible, correction factors should be applied, particularly where estimates of diarrhoeal morbidity a...

Thamnosma africana is ontleed vir chemiese bestanddele. Die vlugtige olie van T. africana is verkry deur stoomdistillasie van die blare, blomme en takkies, en deur middel van GC-MS gekarakteriseer. Die olie is vir biologiese aktiwiteit teen E. coli, B. subtilis en S. aureus getoets en het B. subtilis en S. aureus teen 0.1% verdunning geïnhibeer. Die olie was ook aktief in mikromolare konsentrasies teen Plasmodium falciparum. Chromatografiese skeiding van die etielasetaatekstrak van die bogrondse dele het twee metoksipsoralenisomere (xanthotoxin en bergapten)

Rural households are o�ten dependent on rivers, springs, boreholes or standpipes some distance �rom their homes �or their daily water requirements. Water �or drinking and domestic use is consequently stored in containers in�house which are prone to post�collection contamination. The objective o� the study was to determine the most likely origin or place o� introduction o� E. coli associated with post�collection contamination in rural households, by assessing the degree o� genetic relatedness o� E. coli present in the stored water and other environmental samples. E. coli isolates were obtained using either mFC agar with confirmation of indole production (44 isolates) or Colilert ® -18 (52 isolates). Amplified fragment length polymorphism (AFLP) fingerprinting was applied to determine the genetic relatedness of E. coli isolated �rom in�house storage containers, drink� ing cups, hand-swab samples, cattle dung and from the source water (spring water). DNA fingerprints of E. coli produce...