Bacterial and parasitic profile of acute infectious pediatric diarrhoea and the role of faecal screening tests in prediction of the invasive type of diarrhoea

Diarrhoea is one of the leading causes of morbidity and mortality in children worldwide. Faecal screening methods as detection of faecal leucocytes, faecal lactoferrin and faecal occult blood, have diagnostic and therapeutic implications in the provisional diagnosis of invasive diarrhea before culture results made available. Aim of the work was to outline the bacterial and parasitic profile of acute pediatric diarrhoea and to evaluate faecal screening test in preliminary diagnosis of invasive diarrhoea. Three hundred children under five years of age, suffering from acute diarrhoea [<4 days] and attending the out-patient clinic of El Shatby Children's University Hospital in Alexandria over a period of 1 year, were recruited in the study. Stool samples were collected from the children and were subjected to bacteriological examination, parasitological examination and 3 faecal screening tests to distinguish invasive [inflammatory] from non invasive [non inflammatory] diarrhoea. Forty eight percent of samples were positive for enteric pathogens. Enteric bacterial pathogens were isolated from 25% of samples. Parasites 29% and mixed bacterial and parasitic infections were detected in 6% of samples. Enterotoxigenic E.coli [ETEC] was the most common bacterial isolate detected in 10% of samples, followed by Salmonella [8%], Shigella [6.67%] Campylobacter [5%] and Vibrio parahaemolyticus [1.33%]. Cryptosporidium was the most commonly identified parasite [13%] followed by Giardi lamblia [11%], Entamoeba histolytica [8%] and Cyclospora cayetanensis [3%]. Ascaris lumbricoides and Haeminolipus nana were only identified in 1% of samples, each. The gold standard for evaluation of faecal screening tests was positive culture for invasive bacterial pathogens and/or positive E. histolytica on microscopic examination of stool samples. Leuko test had the highest sensitivity [85.54%], specificity [73.73%], positive predictive value [55.47%], negative predictive value [93.02%] and accuracy [77%]. False positive results of the Leuko-test were significantly higher in the breast-fed children than non breast-fed ones [26.7%, 11.7% respectively, p<0.01]. Better sensitivity, specificity, positive and negative predictive values of the Leuko-test was recorded in the non breast-fed children than in the breast-fed ones. The recorded values in the first group were: 91.11%. 83.64%, 69.5% and 95.83%, respectively compared to 78.95%, 63.55%, 43.48% and 89.47% respectively in the second group. The study concluded that, Leuko test is the best applicable faecal screening test in differentiation of invasive and non invasive diarrhoea but is better avoided in breast-fed infants as many false positive results might be interpreted

Defective monocyte phagocytic function as a possible genetic marker for heumatic susceptibility

The activity of the monocyte phagocytic system in children with rheumatic heart disease [RHD], their parents, their normal siblings and in nonrheumatic families was investigated. Phagocytic activity of isolated monocytes was assessed using luminol-dependent chemiluminescence. The count per minute of emitted light was measured before and after stimulation with zymosan solution. The results indicate that one-third of the siblings of children with RHD were genetically free while two-thirds, as well as the parents, were heterozygous, and that children with RHD were homozygous for [a] mutant gene[s] responsible for the defective function of the monocyte phagocytic system. The findings are strongly suggestive of autosomal recessive inheritance

Detection of enterotoxigenic escherichia coli by DNA colony hybridization method

500 diarrheal stool specimens were obtained from infants and children suffering from acute gastroenteritis. Isolates of E. coli were identified by conventional methods and they were further subjected to phadebact ETEC-LT coagglutination test, suckling infant mouse assay and hybridization with synthetic enzyme labelled oligonucleotide probe for the detection of heat labile enterotoxigenic E.coli and heat stable enterotoxigenic E.coli. ETEC was detected in 20.8% of specimens. The rate of detection of LT enterotoxin by enzyme labelled LT probe was significantly higher than the phadebact ETEC-LT [McNemnar's X[2] =27.0089]. No significant difference for detection of ST by probe and suckling mouse was found [X[2]=0.05]. The DNA probe hybridization, is recommended for ETEC detection, as an easy rapid technique in minimally equipped laboratories