Enterotoxigenic Escherichia coli in the domestic environment of a Malaysian village

Molecular detection of waterborne pathogens in infants' drinking water and their relationship with water quality determinants in eastern Ethiopia: loop-mediated isothermal amplification (LAMP)-based study

Cryptosporidium, Shigella, toxin-producing Escherichia coli, and rotavirus were reported to be the most responsible for severe and fatal diarrhea among infants. This study aimed to investigate the presence of these pathogens in infants' drinking water samples and analyzing using water quality determinants in eastern Ethiopia. A molecular (LAMP)-based cross-sectional study design was employed. A total of 410 and 37 water samples were tested from infant point-of-use at household and corresponding water source, respectively, from June 2020 to May, 2021. Cryptosporidium, Shigella, toxin-producing E. coli, and rotavirus were detected in 28.5, 30.0, 26.3, and 32.2%, of water samples tested from infant point-of-use, respectively. About 13.2% of the water samples were positive for all (four) pathogens together. Cryptosporidium, Shigella, toxin-producing E. coli, and rotavirus were detected in 27.0, 32.4, 29.7, and 37.8%, of water samples tested from water sources, respectively. Positive significant correlation was observed between infant point-of-consumption and water sources from which it is drawn toward the presence of each targeted pathogen. Unimproved water source showed a strong significant association with the presence of Cryptosporidium, Shigella and toxin-producing E. coli. Therefore, efforts should be made in development of improved water sources, source protection safety and health education to caretakers of infants.

Key Food Hygiene Behaviors to Reduce Microbial Contamination of Complementary Foods in Rural Bangladesh

Microbial contamination of complementary foods puts young children at risk of developing intestinal infections and could be reduced by improved handwashing and food hygiene practices. We aimed to identify which promoted food hygiene practices are associated with reduced complementary food contamination in a rural population in Bangladesh. We collected cross-sectional data on reported and observed maternal food hygiene behaviors and measured Escherichia coli counts as an indicator of microbial contamination in complementary food samples from 342 children of women enrolled in the Food and Agricultural Approaches to Reducing Malnutrition trial in Sylhet, Bangladesh. We used multivariable logistic regression to examine associations of food hygiene behaviors with food contamination. Approximately 46% of complementary food samples had detectable levels of E. coli. Handwashing with soap at critical times and fresh preparation of food before feeding were strongly associated with reduced odds of food sample contamination (odds ratio [OR]: 0.8, 95% confidence interval [CI]: 0.6-0.9 and OR: 0.3, 95% CI: 0.1-0.7, respectively); in contrast, there was no or only weak evidence that reheating of stored food, safe food storage, and cleanliness of feeding utensils reduced contamination. Reduction in food contamination could be more than halved only when several food hygiene behaviors were practiced in combination. In conclusion, single food hygiene practices showed limited potential and a combined practice of multiple food hygiene behaviors may be needed to achieve a substantial reduction of complementary food contamination.

Fermented Cereal Gruels: Towards a Solution of the Weanling's Dilemma

The high incidence of diarrhoeal morbidity a the onset of weaning is due in part to consumption of contaminated food. This paper discusses the possible role of fermentation as a household food preparation technology in the improvement of the microbial quality of weaning foods as well as in providing adequate nutrients for infant growth and development. It discusses the extent to which fermented foods provide adequate nutrients; the degree to which fermentation can reduce the levels of aflatoxins, hydrocyanic acid, and other toxins in foods; whether fermentation reduces contamination of weaning foods by pathogens; and the role of fermented foods in reducing diarrhoeal morbidity, severity, and duration.

Escherichia coli contamination of child complementary foods and association with domestic hygiene in rural Bangladesh

OBJECTIVE

To determine the frequency and concentration of Escherichia coli in child complementary food and its association with domestic hygiene practices in rural Bangladesh.

METHOD

A total of 608 households with children <2 years were enrolled. We collected stored complementary food samples, performed spot checks on domestic hygiene and measured ambient temperature in the food storage area. Food samples were analysed using the IDEXX most probable number (MPN) method with Colilert-18 media to enumerate E. coli. We calculated adjusted prevalence ratios (APR) to assess the relationship between E. coli and domestic hygiene practices using modified Poisson regression, adjusting for clustering and confounders.

RESULT

Fifty-eight percentage of stored complementary food was contaminated with E. coli, and high levels of contamination (≥100 MPN/dry g food) were found in 12% of samples. High levels of food contamination were more prevalent in compounds where the food was stored uncovered (APR: 2.0, 95% CI: 1.2-3.2), transferred from the storage pot to the serving dish using hands (APR: 2.0, 95% CI: 1.3-3.2) or stored for >4 h (APR: 2.5, 95% CI: 1.5, 4.2), in compounds where water was unavailable in the food preparation area (APR: 2.6, 95% CI: 1.6, 4.2), where ≥1 fly was captured in the food preparation area (APR: 1.6, 95% CI: 1.0, 2.6), or where the ambient temperature was high (>25-40 °C) in the food storage area (APR: 2.7, 95% CI: 1.5, 4.4).

CONCLUSION

Interventions to keep stored food covered and ensure water availability in the food preparation area would be expected to reduce faecal contamination of complementary foods.

Studies of food hygiene and diarrhoeal disease

Contamination of weaning foods and water with enteropathogenic micro-organisms has been recognised in the past, but its link with the development of diarrhoea by young children in developing countries is lacking. This may explain the unavailability of effective interventions to reduce the risk of diarrhoeal diseases from this contamination. The frequency of contamination of weaning foods with enteropathogens is high in developing countries, and is dependent on the food type, storage time and ambient temperature of storage, the method used, and the temperature reached on re-warming before re-feeding. Other considerations are the bacterial content of cooking and feeding utensils. Fruit and raw vegetables can become contaminated with enteropathogenic micro-organisms by sewage-containing irrigation water, by washing produce and fruits in contaminated water, and how they are processed at home. In most studies reviewed, the level of contamination is higher in weaning foods than in drinking water. Since there is a need to reach a critical level of contamination before illness can occur after the ingestion of an enteropathogen, it is postulated that weaning foods are probably more important than drinking water for transmission of diarrhoeal diseases in developing countries. Several potential interventions have been identified, which should be developed and tested in controlled trials in developing countries. These interventions are needed to reduce contamination of weaning foods in households from developing countries, while adequate facilities for the provision of clean water and sanitation to those communities are placed.

Bacterial contamination of the lacteal contents of feeding bottles in metropolitan São Paulo, Brazil

Reported are the results of a study in São Paulo, Brazil, to evaluate the bacterial contamination of the lacteal contents of feeding bottles prepared in urban households of low (LSE) and high (HSE) socioeconomic groups, involving 100 and 32 mothers of infants, respectively. Samples of the lacteal contents of the feeding bottles were cultured and the medians (25th and 75th percentiles) of the counts (bacteria per ml) were significantly higher in the LSE group: mesophilic bacteria, 555,000 (17,250-4,350,000) in the LSE group and 1615 (20-500,000) in the HSE group; coliforms, 2400 (19-150,000) in the LSE group and 7 (0-7800) in the HSE group. Escherichia coli was isolated from 26% (26/100) of the samples from the LSE group and from 6% (2/32) of those from the HSE group (P = 0.03). In the HSE group, higher coliform counts were associated with foodhandlers other than the mother, lower levels of maternal education, the use of pasteurized milk, and the addition of ingredients other than milk. In the LSE group, feeding bottles prepared using tap water and those prepared for infants aged over 6 months had higher coliform counts. In general, the feeding bottles prepared in the households studied were heavily contaminated, especially in the LSE group.

Detection of Escherichia coli and identification of enterotoxigenic strains by primer-directed enzymatic amplification of specific DNA sequences

The polymerase chain reaction (PCR) was used to amplify DNA sequences from the malB operon of Escherichia coli. All E. coli strains tested yielded the specific DNA fragment. No amplification products were obtained with other Enterobacteriaceae. E. coli strains which produce enterotoxins were identified with additional primer pairs specific for the genes coding for the heat-labile toxin type I (LTI) and the heat-stable toxin type I (STI). Amplification products were identified by DNA-DNA hybridization. Alternatively, restriction endonuclease analysis was used for identification and to distinguish between different alleles of the enterotoxin genes. The detection limit was 10 bacteria. The PCR systems were validated by testing 27 E. coli of known enterotoxigenic properties. The PCR results were consistent with factual toxin production as determined by immunoassays. In addition, 58 E. coli strains isolated from soft cheese and mayonnaise were analyzed by PCR. One strain from a cheese sample was found to have the genetic information for STI production. This strain produced STI as determined by enzyme-linked immunosorbent assay.

Use of inosine-containing oligonucleotide primers for enzymatic amplification of different alleles of the gene coding for heat-stable toxin type I of enterotoxigenic Escherichia coli

A method which employs the polymerase chain reaction (PCR) to identify Escherichia coli strains containing the estA gene was developed. This gene codes for heat-stable enterotoxin type I. The use of an inosine-containing pair of amplification primers allowed the amplification of a specific 175-bp DNA fragment from several different estA alleles. The amplified fragments were identified and distinguished by allele-specific oligonucleotide hybridization and characterized by restriction endonuclease analysis. An extension of the classical two-primer PCR proved to be a very simple and rapid method to identify and characterize the estA alleles. Besides the inosine-containing pair of primers, which recognized all described alleles, additional oligonucleotides were used as primers. The sequence of each of these primers was allele specific, and each was amplification compatible with one of the inosine-containing primers. Thus, in one PCR the 175-bp fragment typical for all estA alleles and an allele-specific fragment of different size were produced. These fragments could be separated by agarose gel electrophoresis and were recognized by ethidium bromide staining. Twenty-seven E. coli strains were tested with this amplification system. The presence or lack of the genetic information for production of heat-stable enterotoxin type I was perfectly consistent with the ability of these strains to produce this enterotoxin, as determined by enzyme-linked immunosorbent assay.

Antimicrobial effect of fermented Ghanaian maize dough

Unhygienic conditions of a typical rural community in a developing country were simulated in the laboratory by inoculating fermented maize dough porridge with Shigella flexneri and enterotoxigenic Escherichia coli (ETEC). The antimicrobial effects of the different processes involved in the preparation of fermented maize dough porridge were assessed. The soaking process reduced the pH but no antimicrobial effect against shigella and ETEC was noted. Unfermented maize dough did not inhibit any of the test strains. When the fermentation process had become established, half of the strains tested were inhibited by the fermented maize dough when examined 8 h after inoculation. Cooking the fermented maize dough into porridge reduced the antimicrobial effect but there was still significant inhibition of pathogens. This suggests that the antimicrobial effect of fermented maize dough is not due to pH per se. Fermentation of maize dough appears to be a useful strategy for reducing contamination of weaning foods by Sh. flexneri and ETEC. The possible nature of the antimicrobial agent(s) produced during the fermentation of maize dough is discussed.