DEERFIELD, ILL. – Antimicrobial resistance has emerged as a global health problem and is a major impediment in managing childhood infectious diseases, according to a new study published in the May issue of the American Journal of Tropical Medicine and Hygiene. Direct and indirect exposure of young children to antibiotics through medical and agricultural usage can increase their risk for carriage of resistant E. coli.

E. coli is estimated to cause disease in hundreds of thousands of people around the world each year, including approximately 70,000 Americans. 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.

Conducted by the Johns Hopkins Bloomberg School of Public Health, the study 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. The study was conducted in 16 purposively selected zones in four regions in Peru, including peri-urban slums in Lima and towns and villages in Cajamarca in the Sierra Mountains, Iquitos in the Amazon rain forest and Chincha on the coast.

“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,” said Dr. Henry D. Kalter, lead study investigator, associate, Department of International Health, Johns Hopkins Bloomberg School of Public Health. “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. 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,” he added. “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 (A.S.T.M.H.). "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.”

“There’s no doubt that antimicrobial resistance is a growing threat to human health,” Dr. Christine Hoang, an assistant director in the Scientific Activities division of the American Veterinary Medical Association, told “In fact, the study indicates that the children’s and the household members’ recent antibiotic use were the two main risk factors for children three years old and younger carrying antimicrobial resistant E. coli.

“Although this study is relatively unique in that it examined the influence of individual, household and community-scale risk factors and potential associations, further study is needed prior to drawing any definitive conclusions,” she concluded.