C. diff is becoming a leading killer in nursing homes, as residents predisposed to the brutal infection by antibiotic treatments in both hospitals and long-term care settings succumb to this opportunistic gut dweller.
Broad spectrum antibiotics in particular can wipe out commensal gut flora and set the stage for C. diff infection (CDI) in this frail, elderly population.
In the U.S. some 1.4 million residents live in nursing homes, with many shuttling back and forth to hospitals for treatment that typically includes antibiotics. Researchers with the CDC recently analyzed population-based surveillance data to estimate the national incidence of nursing home onset (NHO) of CDI.
C. diff caused some 115,400 infections with onset in nursing homes in the United States in 2012, comprising nearly one-quarter of all U.S. CDI cases. Of those, some 8,700 (8%) residents died within 30 days of diagnosis, the researchers reported.1
“This number [of overall cases] is 9% higher than the 104,400 estimated CDIs in nursing homes in 2011 using the same surveillance population,” says Jennifer Hunter, MD, lead author of the study and a CDC epidemic intelligence service officer. “However, this difference is likely related to increased adoption of nucleic acid amplification testing [NAAT] by U.S. laboratories.”
So the increase is at least due in part to more sensitive testing, but with continuing use of the NAAT assay ongoing surveillance will allow more “apple to apple” comparisons in future reports. The highly virulent NAP-1 strain caused almost a third of infections (30%) in both years.
CDI cases were defined as a C. difficile-positive stool collected in a nursing home or within four days after a nursing home stay in a resident without a positive test in the prior eight weeks. Medical records were reviewed on a random sample of cases. The CDC researchers identified a total of 3,506 NHO-CDI cases and extrapolated the findings nationally. Among 262 cases with medical record review, median age was 82 years, 60% were female, 77% received antibiotics in the 12 weeks prior to a C. difficile-positive specimen, and 57% were discharged from a hospital in the month prior. The movement back and forth between long-term and acute care was very much in evidence.
“Among NHO-CDI cases nationwide, we estimated that 31,362 (27%) were hospitalized within seven days of positive specimen,” Hunter says. “These were considered nursing home onset, but in these cases the antibiotics given in hospitals set the patients up for infections.”
Though much of the discussion about antibiotic resistance and stewardship has focused on a future “post-antibiotic era,” the direct correlation between antimicrobial use and CDIs is a clear and present danger. Another recent study quantified this cause and effect phenomenon, determining that each 10% increase in antibiotic use was associated with an increased incidence of CDI of 2.1 per 10,000 patient-days.2
In the CDC analysis, researchers found that antibiotic use in the 12 weeks prior to symptom onset was common for both recently hospitalized NHO-CDI cases as well as those without a recent hospitalization. These findings suggest reducing unnecessary antibiotic use in acute and long-term care settings will be an important factor in decreasing nursing home onset CDIs, they concluded.
However, the nursing home study did not collect information on whether the hospitals and long-term facilities had antibiotic stewardship programs.
“The National Action Plan for Combating Antibiotic-resistant Bacteria calls for strengthening antibiotic stewardship in long-term care settings by expanding existing programs, developing new ones, and monitoring progress and efficiency,” Hunter says.
The reported deaths include both those whose death was directly attributable to C. diff and those who died while they had a CDI, but could have died from other causes, she adds.
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Hunter J, Mu Y, Dumyati, M., et al. National Estimates of Incidence, Recurrence, Hospitalization, and Death of Nursing Home-Onset of Clostridium difficile Infections — United States, 2012. CDC 64th Annual EIS Conference. Atlanta: April 20 – 23, 2015
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Brown K, Valenta K, Fisman D, et al. Hospital ward prescribing and the risks of Clostridium difficile infection. JAMA Intern Med 2015;175:626-633.
