Acute undifferentiated human diarrhea in the tropics. I. Alterations in intestinal micrflora.

The microflora of the small and large intestine was determined in 17 adults with acute undifferentiated diarrhea in Calcutta, India. On the basis of bacteriologic findings, the patients could be divided into two groups: those with a predominant flora of Escherichia coli (eight patients) and those with a mixed coliform flora (nine patients). In the former group, E. coli were distributed throughout the small and large bowel. Broth filtrates of these isolates contained an enterotoxin which caused fluid accumulation in the rabbit intestinal loop model. Toxigenic E. coli were cleared rapidly from the small bowel during the acute period; some patients only had the "hot" strains in their fecal effluent. During convalescence, the serotypes of E. coli changed and the new strains did not elaborate enterotoxin. Only one of the eight patients had a serotype previously associated with diarrhea. Acute undifferentiated diarrhea in the remaining cases was apparently caused by untypable E. coli or by typable strains not generally considered pathogenic. Small bowel and fecal cultures from the mixed flora group revealed a heterogeneous mixture of Gram-negative enteric bacilli and a distinct pattern could not be discerned. Further study will be needed to elucidate the cause of diarrhea in these cases.

Numerical taxonomy of vibrio & allied organisms.

Forty four strains of Vibrio, Pasteurella, Yersinia, Aeromonas, Escherichia, Klebsiella and Enterobacter were tested for 44 characters and the overall results scored by the procedure of numerical taxonomy. The strains were clustered by the weighted pair group method with the arithmatic averaging. The V. cholerae 01 and the non-01 V. cholerae being interlinked at a very high level (86% to 97.5%) within a single cluster were considered under the same species. V.cholerae having Classic, E1 Tor and Gindha (Pfeiffer 1896, as per priority) biotypes respectively. The biotypes of V.parahaemolyticus remained clearly delineated from Vibrio and Aeromonas, and, belonged to a new separate genus. The V. parahaemolyticus biotypes were located more adjacent to Yersinia and Pasteurella than the V. cholerae cluster. V.fluvialis 1 appears as a biotype of V.parahaemolyticus, and, not a new species.

Ischaemic mouse thigh model for evaluation of pathogenicity of non-clostridial anaerobes.

A mouse thigh model has been devised in which the growing culture of non-clostridial anaerobe in the ischaemic tissue produces inflammatory swelling and death. The swelling of the right thigh served as an index of pathogenicity of the test strain in comparison to the negatively reacting left thigh which received injection of the control strain of Bifidobacterium infantis. Actinomyces naeslundii exceptionally caused death in all animals within 24 h. Mortality and thigh swelling were pronounced (greater than 75%) in case of Fusobacterium gonidiaformans and Propionibacterium acnes but less (less than 50%) in Acidaminococcus fermentans. High (less than 75%) rate of thigh swelling was also encountered in case of Bacteroides oralis, Bacteroides corrodens, Fusobacterium necrophorum, Fusobacterium prausnitzii, Fusobacterium plauti, Peptococcus prevotii, Streptococcus intermedius, Eubacterium lentum and Propionibacterium freudenreichii ss. shermanii.

Etiology of acute childhood diarrhoea in Calcutta.

Of the 152 cases of acute diarrhoea, 124 (81.5%) revealed potential pathogens. Altogether 27 (21.2%) out of 127 strains of Escherichia coli, Klebsiella pneumoniae, Enterobacter, Proteus and Acinetobacter produced enterotoxin. Single pathogenic bacteria (40 cases 26.3%), parasite (6; 6%), rota virus (6; 6%), toxigenic bacteria (19; 12.5%) and mixed agents (37; 24.24.3%) were recorded in 108 cases (71.0%). Another 14 (9.2%) cases exclusively revealed moderate to heavy growth of suspected enteric pathogens like K. pneumoniae, Proteus, Enterobacter, Pseudomonas aeruginosa, anaerogenic E. coli and Citrobacter and 2 (1.3%) had high counts of T'. hominis. Of the known pathogens, the preponderance of A. hydrophila (24.4%), rota virus (15.7%) and Aeromonas hydrophila (14.0%) in 1-4 y, Vibrio cholerae (45.6%) and Trichuris trichiura (13.0%) in 4-14 y age group is highlighted. Other pathogenic bacteria were non-01 V. cholerae (3.2%), V. parahaemolyticus (2.6%), V. fluvialis (0.6), Plesiomonas shigelloides (3.9%), Salmonella (2.6%), Shigella (1.9%), EPEC (1.9%), EEC (5.2%) and Campylobacter jejuni (3.9%) and the parasites were Entamoeba histolytica (2.6%) and Giardia intestinalis (2.6). Comparative study of age matched controls with those of diarrhoea suggested the pathogenic role of E. histolytica and T. hominis.

Sensitivity of the different tests of enterotoxigenicity of Escherichia coli and their correlation.

Enterotoxigenicity of E. coli isolates was tested in 136 cases of acute gastroenteritis. Heat labile toxin (LT) produced in-vitro was tested in rabbit ileal loop (RIL); vero cell line and Biktn plate. The results of live cultures were evaluated in RIL. The overall data of these four models were not statistically different. Elaboration of LT in these four models ranged from 14-21.4%. Out of the 20 LT producing strains 14 (70%) also revealed ST. Of the 6 positive reactors on vero cell line, appeared to produce vero toxin (VT) only. Out of 29 LT positive E. coli, 1 (3.45%) and 2 (6.89%) strains respectively revealed colonising factor antigen (CFA) I and II. The high incidence of ETEC showing both LT and ST has been highlighted in the age group 0-4 years, and its impact on nutritional status is discussed.