B.S. Drasar

Fermentation of cereals for reduction of bacterial contamination of weaning foods in Ghana.

Unfermented and fermented maize dough weaning foods prepared by mothers in a Ghanaian village were examined for gram-negative bacilli (GNB) immediately after preparation and during storage to assess the antimicrobial effect of fermentation. GNB were cultured from all samples of unfermented dough (51) and from 16 of 51 samples of fermented dough. The extent of contamination was significantly higher in the unfermented dough than in fermented dough (5.9 [SEM 0.1] vs 4.0 [0.4] log10 colony forming units/g). After 6 h and 12 h storage, a higher proportion of samples of porridge made from unfermented dough contained GNB than did those made with fermented dough (45/51 vs 22/55; 49/51 vs 20/51, respectively) and levels of GNB were significantly higher in the porridge made from unfermented dough after 6 h (4.2 [0.2] vs 3.8 [0.2]). Fermentation of maize dough is an effective method to reduce contamination of maize dough weaning foods with GNB.

Bacterial colonization of jejunal mucosa in giardiasis

Nine of 14 cases of giardiasis and severe malabsorption were found to have numerous bacteria adjacent to the mucosa and within luminal fluid samples from the upper jejunum. Three species of enterobacteria (Klebsiella pneumoniae, Enterobacter cloacae and E. hafniae) were cultured from eight patients and from only one were Bacteroides isolated. Enterobacteria were not cultured from seven of eight patients who had giardiasis but only mild malabsorption (of xylose only) nor from seven patients without malabsorption. Intestinal colonization by enterobacteria may make an important contribution to the development of malabsorption in patients with giardiasis.

CHOLERA AND ESTUARINE SALINITY IN CALCUTTA AND LONDON

Abstract Laboratory investigation has shown that Vibrio cholerae requires a salinity of at least 0·01% to survive beyond 24 h. This requirement, when coupled with the observation that water becomes unpalatable at salinities above approximately 0·1%, suggests that waterborne transmission of cholera is unlikely to take place when water salinity falls outside the range 0·01-0·1%. A hypothesis is proposed that this constraint on waterborne transmission, together with the seasonal fluctuations of estuarine salinities, may explain the seasonality of cholera in estuarine cities.

Survival of toxigenic Vibrio cholerae O1 with a common duckweed, Lemna minor, in artificial aquatic ecosystems

Cholera epidemics occur twice a year in Bangladesh. During epidemics, Vibrio cholerae O1 are isolated from patients, as well as from the surface water, but the bacteria disappear during inter-epidemic periods. Their reservoirs or sites of survival and multiplication during inter-epidemic period are still unknown. The present survival study in the laboratory explored the role of an aquatic plant, Lemna minor (duckweed), as a possible reservoir. L. minor was added to sea-salt solution at pH 8.5, containing V. cholerae. Survival of V. cholerae on L. minor, in water on which L. minor was floating, and in control water (without L. minor) was monitored at regular intervals. Survival of both environmental and clinical strains of V. cholerae was assessed by viable counts on thiosulphate-citrate-bile salt-sucrose agar. It was observed that both strains survived better on L. minor than in water on which L. minor was floating or in control water. It is suggested that plants may serve as an effective environmental reservoir for V. cholerae either through a non-specific association or by interaction with V. cholerae in commensal relationship.

Water supply and nutritional status in rural northern Nigeria

A high incidence of protein energy malnutrition (PEM) was found in a community survey of preschool children in rural northern Nigeria among whom gastro-enteritis is common. Wasting (less than 80% Weight/Height) was more common (37.9%) among those with scanty, unprotected water supplies than in those with copious protected water (10.2%) whereas the incidence of stunting (less than 90% Height/Age)) was similar. Severe coliform contaminatin of all water sources was demonstrable. Even higher numbers of coliforms in foods sampled suggests that other factors related to water supply may be more important than water purity in the genesis of the PEM/gastro-enteritis complex.

Bacterial colonisation of jejunal mucosa in acute tropical sprue.

Fifteen of sixteen Caucasians with acute tropical sprue were founc to have numerous aerobic bacteria closely associated with the mucosal layer of the proximal jejunum. Four species of Enterobacteria were grown in eleven patients, and concentrations were higher in the mucosal patients than in the jejunal fluid. Only one of eight control cases with similar tropical exposure but without mucosal morphological abnormalities had any similar bacteria in the mucosal biopsy. In no case were Bacteroides isolated. Since clinical and biochemical improvement only occurred on treatment with tetracycline when enterobacteria were eliminated from the mucosa, it is suggested that these organisms may be responsible for persisting jejunal abnormalities in tropical sprue.

The study of hygiene behaviour in Botswana: a combination of qualitative and quantitative methods

This paper describes a study from northern Botswana which explored the relationship between hygiene behaviour and diarrhoeal diseases in young children. Both qualitative and quantitative data collection methods were used. The qualitative methods included observations, key informant interviews, in‐depth interviews and focus groups. The quantitative methods included spot check observations, anthropometric measurements, the monitoring of diarrhoea morbidity and the administration of a socioeconomic questionnaire. A profile of hygiene behaviours was developed for this community and traditional beliefs related to diarrhoea were identified. The methods described provided considerable information in a short period of time. They were also relatively inexpensive and easy to implement, thus providing a model for further studies dealing with hygiene behaviour in developing countries. The information gathered enabled the identification of areas needing further research, the development of health education programmes and provided the basis for larger epidemiological studies.

Ribotyping and DNA macrorestriction analysis of isolates of Burkholderia pseudomallei from cases of melioidosis in Malaysia

Forty-nine isolates of Burkholderia pseudomallei from sporadic cases of melioidosis in Malaysia over the past 18 years were examined by BamHI ribotyping and pulsed-field gel electrophoresis (PFGE) of XbaI digests of total deoxyribonucleic acid (DNA). Twenty-four patients had septicaemic melioidosis with a mortality of 70%; mortality in the non-septicaemic disease was 16%. Five ribotype patterns were identified, 2 of which accounted for 90% of all isolates. PFGE revealed a number of different strains within these ribotypes, but some pairs of isolates from unrelated cases gave closely similar DNA profiles. These results are in agreement with Australian studies which showed a high prevalence of a few ribotypes of B. pseudomallei which are further divisible by genotyping, in areas where melioidosis is endemic.

Human serum antibody response to Helicobacter pylori whole cell antigen in an institutionalized Bangladeshi population

J. NESSA, H. CHART, R.J. OWEN AND B. DRASAR. 2001.

Stability of strain genotypes of Burkholderia pseudomallei from patients with single and recurrent episodes of melioidosis

The constancy of strain genotypes of multiple isolates of Burkholderia pseudomallei from 13 patients with melioidosis was examined by BamHI ribotyping and pulsed‐field gel electrophoresis (PFGE) of XbaI digests of DNA. Seven of 8 patients with single episodes of melioidosis each yielded genetically identical isolates and only one of five patients with recurrent episodes was infected with a new strain clearly distinct from the original primary strain. Variation was observed in PFGE patterns of primary and relapse isolates of another patient but this was insufficient to define genetically distinct strains. We conclude that most patients with single or multiple episodes of melioidosis retain a single strain.