Infections from a lesser-known foodborne pathogen most commonly associated with infants may be more common in elderly populations — and even adults and adolescents — than previously thought, according to a new study by researchers at the U.S. Centers for Disease Control and Prevention. The study, set to be published in the September issue of Emerging Infectious Diseases, was intended to define the impact of Cronobacter on various demographics in the U.S. using data collected by FoodNet, the CDC’s foodborne illness surveillance network in 10 states. It was the first study to look at rates of Cronobacter infections in groups other than infants, said Dr. Anna Bowen, CDC epidemiologist and one of the study’s authors. In the U.S., Cronobacter has been most commonly connected to outbreaks involving powdered infant formula, though the bacteria has also been found in powdered milk, teas and starches. In infants younger than one year old, infections can enter the bloodstream or cause meningitis, swelling of the brain and spine. In adults, symptoms can manifest as infections in the blood or urinary tract. The study found that about 3.9 out of 100,000 people older than 65 were infected with the bacteria. That’s more than twice the number of infants infected, at 1.8 in 100,000. “We were really surprised to find such a high rate of infection among the elderly,” Bowen said. Out of 540 laboratory isolates between 2003 and 2009 included in the study, the vast majority were found in either infants or the elderly, she added. Much of the attention related to Cronobacter may center on infants because they suffer from the most severe infections, said Mary Patrick, CDC epidemiologist and the main author of the study. Symptoms are milder in adults, while the bacteria can kill up to 40 percent of infants who suffer from meningitis due to their infections. For parents who want to minimize their child’s exposure to Cronobacter, CDC recommends breastfeeding whenever possible. Experts also recommend liquid infant formula over powdered, as the liquid variety has been pasteurized, Patrick said. When the only option is powdered formula, CDC recommends preparing it with water heated to at least 158 degrees F (70 degrees C) to eliminate any potentially harmful bacteria. Where are all these Cronobacter infections in adults coming from? Answering that question is next on the research agenda, according to Patrick. “These Cronobacter infections obviously come from someplace,” she said. “I like to think of this study as the first step in figuring that out.”