Molecular and phenotypic characterization of shigatoxigenic Escherichia coli (STEC) and enteropathogenic E. coli (EPEC) from piglets and infants associated with diarrhoea in Mizoram, India

Abstract

Limited information is available on shiga toxin producing Escherichia coli (STEC) in pigs and infants from Aizawl, Mizoram and North Eastern region of India. This cross sectional study was conducted on faecal samples from pigs and infants to detect and characterize of STEC and enteropathogenic E. coli (EPEC). Serogrouping, molecular and phenotypic characterizations were done by standard molecular and cytotoxic assays. Out of 48 E. coli strains isolated from 320 diarrhoeic fecal samples of piglets, 44 belonged to 18 different serogroups, 3 (6.25%) were untypeable (UT) and 1(2.08%) was recorded as rough strain (R). Similarly, out of 17 E. coli strains isolated from 264 diarrhoeic fecal samples of infants, 16 belonged to O60 (94.1%) and 1(5.88%) was untypeable. Virulence genes (stx1, stx2, eaeA and hlyA) were detected by multiplex PCR assay. A total of 1260 E. coli were isolated from piglets (720) and infants (540) from 584 faecal samples. All together, 5.16% (65) E. coli isolates were found to be positive for at least one virulence gene (6.66% piglets and 3.15% infants). Out of the virulent gene positive E. coli 3.17% (32 from piglets and eight from infants) and 1.98% (16 from piglets and nine from infants) were recorded as STEC and EPEC, respectively. On the other hand, from the total 2.14% stx 2 positive isolates, 16 and 11 were positive for stx 2e and stx 2c subtypes, respectively. Similarly, from the 4.04% eaeA positive isolates, 1.19% (15) were positive for bfpA gene, of which 1.67% (12) were piglets and 0.60% (3) were infants. All the isolates were exhibited varying degree of CPE on vero cell lines. In conclusion, STEC and EPEC seem to be associated with diarrhoea in piglets and infants in Mizoram. In piglets STEC strains represent as a major cause of diarrhoea while EPEC strains represent as major cause of diarrhoea in infants in North Eastern region of the India.

Prevalence of multi drug resistant enteropathogenic and enteroinvasive Escherichia coli isolated from children with and without diarrhea in Northeast Indian population

“…Among all the DEC, EPEC found to be the most common pathotypes for diarrheal infection in Mizoram which is much higher than the previous report [15]. Recent studies from other part of India also found higher occurrence of EPEC compared to EIEC among diarrheal samples [8, 16, 22].…”

“…Thus, the exact burden of E. coli diarrhea among the hospitalized children across India especially Northeast India is still unclear. In the present study, the samples were collected from Mizoram, located in the North Eastern part of India adjoining to Myanmar and Bangladesh where limited study has been conducted on the prevalence of diarrhea associated with DEC [15, 21]. This is the first report on an in-depth study on the prevalence of EPEC and EIEC associated with diarrhea in children less than 5 years of age in North-eastern Indian population.…”

“…For many decades tEPEC isolates were considered as the major pathogen in infants in developing countries including India [6, 22], but few sporadic reports indicated the association with aEPEC with children diarrhea [6, 7, 22]. In contrast to typical EPEC, atypical EPEC strains appear to be common in domestic animals, raw meats and have been reported in food borne and water borne outbreaks [5, 9, 15]. This might be the possible source of transmission of this pathogen among children through mother, baby sitter or other members of the family.…”

“…and the pellet obtained was dissolved in autoclaved distilled water followed by boiling for 10 min. The bacterial lysate was centrifuged again and the supernatant was finally taken as template DNA for PCR assay [15]. The specificity of the multiplex PCR assay was determined by using locally available and or reference strains as positive control strains ( E. coli O20 serotype positive for eaeA, bfpA genes of EPEC and E. coli ATCC ® 43893 positive for ial gene of EIEC) for the standardization of multiplex PCR assay.…”