Bacterial Infection's Spread Occurs Beyond Health Care Settings: Study
Review of C. difficile suggests most transmission takes place outside of hospitals, nursing homes
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There are about 250,000 C. difficile infections a year in the United States that either require hospitalization or involve already hospitalized patients. The bacteria kills 14,000 Americans a year, the CDC says.
In the new study, the Oxford researchers tested nearly 41,000 stool samples from patients for C. difficile. They cultured the bacteria and then genetically analyzed every strain to see which ones shared genetics and, therefore, were likely to have been transmitted from one patient to the other.
"The sources of Clostridium difficile infections were highly genetically diverse, with 45 percent of cases having a genetically distinct origin, suggesting a diverse reservoir of disease not previously appreciated," Eyre said.
That reservoir might be located inside or outside the hospital, editorial author Donskey said. People might be contracting the bacteria at the hospital from carriers who show no symptoms, or they could be contracting it from sources in the community such as water, food, animals, infants or other health care facilities such as nursing homes.
"I think the molecular typing they are doing will be one key way we can figure out where it's coming from," Donskey said. "We can combine our basic "shoe leather" epidemiology with molecular typing to get an answer."
Interestingly, the overall rate of C. difficile in Oxfordshire fell during the three-year study, Eyre noted, and suggested that more limited use of antibiotics might be a reason.
"This suggests that the decline in Clostridium difficile was due to factors that prevent the transition from simple exposure and asymptomatic carriage to overt disease," he said. "The main factor known to determine this is antibiotic exposure, particularly quinolones and cephalosporins. The use of these antibiotics fell significantly in the U.K. during the three years of the study. Hence, it is likely that the fall in incidence in Clostridium difficile was likely to be due to restriction of use of antibiotics rather than an improvement in infection control."