OCCURRENCE OF ENTEROAGGREGATIVE ESCHERICHIA COLI IN ANIMALS, HUMAN INFANTS AND ASSOCIATED ENVIRONMENTAL SOURCES IN ERNAKULAM
Loading...
Date
2019-09-30
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
COLLEGE OF VETERINARY AND ANIMAL SCIENCES MANNUTHY, THRISSUR
Abstract
The present study was undertaken to find out the occurrence of
Enteroaggregative Escherichia coli (EAEC) in young animals, human infants and
associated environmental sources in Ernakulam district, Kerala. All the samples
procured during a period of 12 months from August 2018 to July 2019. During the
study diarrhoeic faecal sample of young animals viz., calves and piglets were
collected from individual cattle and pig rearing households of two panchayats in
Ernakulam district. To study the environmental association water and soil samples
were also collected from the animals rearing areas. Finally to study the occurrence
in human beings, infant diarrhoeic stool samples were collected from primary
health care units, hospitals, anganwadis and diagnostic laboratories of Ernakulam
district. The samples collected were aseptically processed by conventional cultural
technique. Molecular confirmation of EAEC was done by performing polymerase
chain reaction (PCR) that targeted conserved genus specific 16SrRNA gene and
virulence genes viz., astA, Pic, aggR and fimA genes with amplicon size 231, 106,
1111, 251 and 342 bp, respectively. The isolates were subjected to biofilm assay
using a 96-well microtitre plate. To understand the antibiotic resistance profile, all
the isolates were subjected to standard disc diffusion method for commonly used
antibiotics. Thus the study gives information regarding occurrence of EAEC in the
Ernakulam district and the risk associated with it.
All the procured samples were initially subjected to isolation of E. coli
through conventional cultural and biochemical techniques and E. coli could be
recovered from 51and 42 samples of calves and piglets respectively. From the
environmental samples, 30 soil samples and 62 water samples showed positive for
E. coli. Among the human infants samples, 39 samples revealed positive for E.
coli. All the 224 E. coli isolates were subjected to a genus specific 16SrRNA
which affirmed that all the isolates belong to the genus Escherichia. All these E.
coli isolates were further subjected to PCR for the detection of virulence
associated genes belonging to EAEC. Four oligonucleotide primers targeting the
EAEC viz., heat-stable toxin (astA), mucinase (Pic), transcriptional activator
aggregative gene (aggR) and fimbrial subunit gene (fimA) were used in the study
for detection of EAEC. On analysis 21.57 per cent, 5.89 per cent, 5.89 per cent
and 15.69 per cent of the E. coli isolates from calf diarrhoeal samples carried the
astA, pic, aggR and fimA genes respectively. From the piglets’ diarrhoeal samples,
astA, pic, aggR and fimA genes were detected from 9.52 per cent, 9.52 per cent,
4.76 per cent and 23.81per cent of E. coli isolates respectively. From water and
soil samples of calves rearing areas seven E. coli isolates carried virulence genes.
Of the piglets rearing areas only two isolates from water carried the virulence
genes where as soil samples remained negative. Out of 39 E. coli isolates from
human infant diarrhoeal samples 20.51 per cent, 7.69 per cent, 7.69 per cent and
17.94 per cent carried astA, pic, aggR and fimA genes respectively.
To study the biofilm forming ability, all the EAEC isolates were subjected
to quantitative biofilm assay through which it was inferred that the 84 and 78.57
per cent of isolates from calves and piglets were low biofilm producers whereas
only 10.5 and 7.14 per cent showed high biofilm forming ability. None of the
isolates from environmental sources showed high biofilm forming ability. From
human infants only two isolates showed high biofilm forming ability whereas 81.2
per cent were low biofilm producers.
On antibiotic sensitivity study, EAEC isolates from calves showed highest
resistance towards ampicillin (84 per cent) followed by cefotaxime (57.89 per
cent). Among the isolates from piglets resistance was observed with cefotaxime
and tetracycline (79 per cent). From environmental sources norfloxacin (78 per
cent), cefotaxime and tetracycline (77.7 per cent) showed highest resistance. In
human infants EAEC isolates showed highest resistance against ampicillin,
streptomycin (75 per cent) and azithromycin (68.75 per cent). All the isolates
were sensitive to imipenem. Further sensitivity was observed among
nitrofurantoin and meropenem. From the study it was concluded that EAEC is an
emerging pathogen of public health importance because of its ability to form
biofilm and increasing antibiotic resistance towards commonly used antibiotics.
Description
Thesis Submitted in partial fulfilment of the requirement for the degree of Master of veterinary Science in Veterinary Public Health