Diarrheal diseases are a major cause of illness in many parts of the world particularly affecting infants and children leading to a high degree of morbidity and mortality, which contributes to the death of 3.3 to 6 million children annually. Detection of the etiological agents of diarrhea is important for therapeutic aspects and for implementing appropriate control strategies.

In developing countries, the bacterial pathogens most commonly associated with endemic form of diarrhea is diarrheagenic Escherichia coli [DEC]. Diarrheagenic Escherichia coli belongs to different categories of pathotypes, which are classified based on their distinct clinical features, virulence mechanisms and serotypes. Currently, 5 distinct pathotypes of DEC are recognized: ETEC, EPEC, EaggEC, EHEC and EIEC(1).

Accordingly, a prospective study of acute and persistent diarrhea was carried out in a cohort of children in a rural place located in the coastal belt of Karnataka, South India from May 2001-June 2003.

One hundred and sixty eight children aged between 0-5 years admitted to the Pediatric ward of Kasturba Medical College Hospital, Manipal with watery diarrhea for more than 2 weeks, abdominal cramps with or without fever were included for the study. Seventy-five age-matched infants and children without diarrhea during the last 3 weeks served as controls. Three Escherichia coli colonies per specimen were further characterized by pathotype specific virulence gene targeted PCR assays. A multiplex PCR assay was applied for the detection of Eagg E. coli [Eagg, ast], ETEC[elt, est], EPEC[ eae,bfpA] genes at NICED, Kolkata.

The other enteric pathogens were identified using recommended standard procedure(2). Detection of Rotavirus antigen [Mercia Diagnostics Ltd, England] and demonstration of Cryptosporidium and Isospora was done by modified Z-N staining and Immunofluorescence technique(3).

EPEC

4

4.87

–

   –

ETEC

6

7.32

–

–

EaggEC  

18

21.95

–

–

Salmonella typhimurium

11

13.41

2

2.66

Shigella spp

8

9.76

–

–

Vibrio cholerae

2

2.43

–

–

Aeromonas hydrophila

8

9.76

3

   4

Chromobacterium violaceum

2

2.43

–

–

 Cryptosporidium  

4

4.87

1

1.33

 Rotavirus

16

19.51

3

4

 Candida albicans

2

2.43

–

–

A total of 82 (48.8%) Enteric pathogens were isolated from acute diarrhea (Table I). Bacterial isolates were highest (71.93%) where Eagg E. coli predominated (21.95%). Age wise analysis showed that Eagg E. coli and Aeromonas diarrhea was common between 13-24 months of age and that of Rotaviral diarrhea was seen in 7-12 months age. To determine how well the various pathogens correlate with diarrhea, age-matched controls were used. Entero-aggregative E. coli was seldom isolated from control group.

Eagg E. coli was the most common cause of diarrhea in children below 5 years of age followed by Rotavirus. The strains of S. typhimurium and Shigella were found to be multiple drug resistant strains. With the benefit of experiences from other workers, it is suggested to use fluoroquinolones in neonatal diarrhea in instances of proven infection with MDR strains(4).

In the present study, Eagg E. coli was the commonest isolate from infantile diarrhea and their isolation from children below 2 years correlates well with studies elsewhere(5). In 21.95% of the patients from whom Eagg E. coli were isolated, it was the sole pathogen recovered. The incrimination of Eagg E. coli as a cause of persistent diarrhea in developing countries is an interesting and potentially important observation over here in a rural cohort area of South India.

Dr. G.B. Nair, Director, Laboratory Sciences Division, ICDDR, Center for Health and Population Research, Dhaka 1212, Bangladesh, for carrying out the molecular characterization of the isolates of Escherichia coli.

Mamatha Ballal,Ramamurthy T.,
Departments of Microbiology,
KMC,Manipal,
Karnataka, India
and
National Institute of Communicable
Diseases, Kolkata,
India
Correspondence to:
Dr. Mamatha Ballal,
Additional Professor of Microbiology,
KMC, Manipal 576 104. Karnataka,
India.
E-mail:[email protected] 

1. Bern C, Martins J, Dezoysa I. The magnitude of the global problem of Diarrheal Diseases. A ten year update. Bull World Health Organisation, 1992; 70: 705-712.

2. Barrow GI, Feltham RKA. Cowan & Steel’s Manual for the identification of medically important Bacteria. 3rd edn. Great Britian: Cambridge University Press; 1993; 140-145.

3. Gracia LS. Laboratory methods for diagnosis of Parasitic infections. In: Baron EJ, Peterson LR and Finegold SM, Eds. Bailey & Scott’s Diagnostic Microbiology, 9th edn. St Louis; The CV Mosby Co, 1990; pp 776-786.

4. Threlfall EJ, Ward LR,Rowe B, Raghupathi S, Chandrasekaran V, Vandepitte J, et al. Widespread occurrence of multiple drug resistant Salmonella typhi in India. Eur J Clin Microbiol Infect Dis.1992; 11: 990-993.

5. MK Bhan, P Raj, MM Levine, JB Kaper, N Bhandari, R Srivastava, et al. Entero-aggregative E. coli associated with persistent diarrhea in a cohort children in India. J Inf Dis 159; 6: 1061-1064.