The vultures were resistant to certain antibiotics when they arrived and developed resistance to certain other antibiotics when they left, say Pradeep Sharma and Gopi Sundar. – Photo: Pradeep Sharma.

Researchers found a significant change in the pattern of drug resistance in E. coli seen in Egyptian vultures that come to India for wintering. They were resistant to certain antibiotics when they arrived and developed resistance to certain other antibiotics when they left.

The E. coli seen in over 90% of Egyptian vultures that migrate to northwest India to spend the winter (October to March the next year) tend to show significant difference in resistance pattern within a single season, a study shows. The resistance pattern showed significant difference between one year and the succeeding year.

The resistance to multiple antibiotics was as high as about 71.5% in E. coli collected from vultures. Resistance of 12-13 E. coli bacteria species to 13 commonly used antibiotics was studied. The vultures arrived in October 2011 and flew back in March 2012 and were feeding on carcasses dumped in Jorbeer in Bikaner, Rajasthan.

“The diversity of E. coli community in vultures changed and became homogenised by the end of the wintering period. This is due to the environment that the vultures were exposed to — carcasses, garbage, and domestic animals,” says Dr. K.S. Gopi Sundar from the Nature Conservation Foundation in Udaipur and one of the authors of a paper published in the journal Infection Ecology and Epidemiology.

“This is an important study because people had predicted that there would be a change in bacterial community in wild species in the environment. We have now documented it for the first time,” he says.

“There is not much difference in the percentage resistance to multiple antibiotics that are commonly used. What we found was a change in the pattern of resistance,” says Dr. Pradeep Sharma from the College of Veterinary and Animal Science, Rajasthan University of Veterinary and Animal Sciences, Bikaner, Rajasthan and corresponding author of the paper.

“The vultures were resistant to certain antibiotics when they arrived and developed resistance to certain other antibiotics when they left. Their sensitivity to certain antibiotics also changed within a few months,” says Dr. Sharma.

The study found a change in the E. coli community in the vultures and significant change in the resistance pattern of the E. coli within a single wintering season. The E. coli community in October was distinctly different from the other months, particularly March.

The vultures that use human-dominated landscape as part of life history are likely to act as “reservoirs and melting pots of bacterial resistance”. Wild birds travelling thousands of kilometres across continents often carry disease-causing microbes such a H5N1 (bird flu)-causing virus and cause the spread of the disease. These birds could also carry different drug-resistant bacteria.

The present study helped show that vultures are able to incorporate and reflect resistance determinants at the site of wintering and during the period of sampling. “So guidelines to restrict antibiotic use in both humans and animals by one country or region alone will be inadequate when wild birds can spread drug-resistant bacteria,” says Dr. Sundar.

Correction: The article had wrongly mentioned that bird flu is spread by bacteria. It has been corrected. 

Published in The Hindu on March 15, 2018