Personal and agricultural antibiotic use increasing resistant E. coli in Peruvian children

10 May 2010

Direct and indirect exposure of young children to antibiotics through medical and agricultural usage can increase their risk for carriage of antibiotic resistant E. coli, according to a new study published in the May issue of the American Journal of Tropical Medicine and Hygiene.

Antimicrobial resistance has emerged as a global health problem and is a major impediment in managing childhood infectious diseases.

It is estimated that E. coli causes disease in hundreds of thousands of people around the world each year. E. coli can be transmitted from animals and humans through several sources, the most common being contaminated food and water. While most E. coli are harmless, and are carried as a normal part of the human intestinal flora, such commensal bacteria might serve as an important reservoir of resistance that can be transmitted to disease-causing E. coli and other bacterial species.

The study, conducted by the Johns Hopkins Bloomberg School of Public Health, revealed several factors affecting antibiotic-resistant E. coli carriage in young children in Peru. By analyzing E. coli samples from more than 500 children, the researchers were able to identify individual, household, and community factors influencing carriage of the resistant bacteria.

"This study is unique in having evaluated a number of risk factors at multiple levels in very young children for carrying antibiotic-resistant E. coli bacteria. By examining all these factors, we were able to reach a more comprehensive understanding of how resistant E. coli is transmitted in the developing world," said lead study investigator Dr. Henry D. Kalter, Associate, Department of International Health, Johns Hopkins Bloomberg School of Public Health.

"In analyzing the study results, we learned that children's use of antibiotics, as well as their family members' use, increased their risk for carrying resistant E. coli, and that residing in an area where a greater proportion of households served home-raised chickens protected against resistance.

"This protective effect can be understood in light of the fact that the home-raised chickens carried significantly lower levels of resistant E. coli than did the market chickens, which in Peru are intensively raised with antibiotics. The strength of this community level variable suggests that this is where the transmission of resistance resulting from agricultural antibiotics use was taking place."

In poor communities in developing countries (such as Peru), with inadequate protection of excreta and water, contamination of the environment with antibiotic-resistant bacteria appeared to play at least as great a role in children's carriage of resistant E. coli as did the children's own antibiotics use.

"This study is important in a number of respects," said Edward T. Ryan, M.D., President, American Society of Tropical Medicine and Hygiene (ASTMH). "It improves our understanding of the growing global public health threat of antibiotic-resistant organisms, and underscores the critical role that antibiotic use in animals plays in contributing to this threat. The vast majority of the tons and tons of antibiotics ingested each year on this planet are administered to livestock and animals. This study clearly shows that such use comes with a very real cost to human health."