PCR: An Efficient and Fast Detection Method for Escherichia coli

Escherichia coli (E.coli) is a a facultative anaerobic and gram negative bacteria which belongs to the family Enterobacteriaceae¹. This bacteria is reponsible for many diseases and disorders. Gastroenteritis is a one of the disorder caused by E. coli which leads towards inflammation of the stomach as well as intestines due to bacterial toxins or viral infection and ultimately causes vomiting and diarrhoea. Some harmful strains of E. coli can also cause food poisoning in their hosts².

These bacteria flourish and develop in the pollution produced from human and animal waste, that’s why E. coli is often termed as faecal indicator. Therefore, rapid identification of these bacteria through reliable method is needed.

In recent times, effective cultivation media to observe E. coli in freshwaters have been established. Those procedures are normally used in a quantitative way to guess the actual concentration of E. coli. However, with these methods, differentiation can’t be done. Therefore, techniques for the immediate detection as well as differentiation of E. coli populations in aquatic environments are needed.

Currently, the polymerase chain reaction (PCR) has been proliferated due to its simplicity, rapidity, reproducibility, reliability, sensitivity as well as specificity to examine microorganisms. It is actually a molecular- biological procedure that is being used efficiently in almost every area of medicine and natural sciences. PCR has also confirmed suitable to support the conventional bacteriological procedures as well as DNA hybridization technique³.

This situation urged scientists for performing a new experiment to evaluate conventional methods and PCR assay for detection and differentiation of E. coli strains in environmental samples.

For this purpose, scientists isolated the organism through conventional bacteriological methods. Afterwards, identification of the nucleic acid sequence of the organism was confirmed by means of PCR based detection assay. In the PCR assay, a pair of primers derived from uidA gene of E. coli, encoding glucuronidase specific for E. coli was employed⁴.

Results showed that conventional isolation and identification is the most precise technique for detection of an active organism in environmental samples. But, it is tiresome, difficult and time consuming process. On the other hand, it was concluded that polymerase chain reaction is a reliable, fast, sensitive and specific assay to examine E.coli strains. Last but not the least, it is recommended that PCR should be used for the detection and identification of E. coli.

REFERENCES

1. Migula, W., 1985. Bacteriaceae (Stäbchenbacterien). In: Die Natürlichen Pflanzenfamilien, Ehgler, A. and N. Prantl (Eds.). W. Engelmann Publishers, Leipzig, Germany, pp: 20-30.
2. Adams, M.R. and M.O. Moss, 2000. Food Microbiology. 2nd Edn., Royal Society of Chemistry, University of Surrey Guildford, UK.
3. Aradaib, I. and N. Ali, 2004. Current status and future prospects of epizootic haemorrhagic disease of deer-a review. Vet. Arhiv., 74: 63-83.
4. Sherfi, S.A., I.E. Aradaib and H.A. Dirar, 2006. Evaluation of polymerase chain reaction for rapid detection of E. coli strains: A preliminary study. Asian J. Cell Biol., 1: 9-13.