Increases in the C. difficile infection (CDI) incidence, severity and mortality were reported in the early 2000s due to the emergence of the NAP1/027 strain. We evaluated the trends in incidence, mortality, hospitalization, and the prevalence of NAP1/027 strain in Monroe County, NY.
We conducted population and laboratory-based surveillance for CDI from 2011-2016 as part of the CDC Emerging Infections Program. An incident CDI case is defined as a positive C. difficile stool specimen from a resident of the county aged >1 year with no positive test in the prior 8 weeks. All the laboratories in our catchment area used nucleic acid amplification for diagnosis starting in 2011 as part of single or 2-step algorithm. A convenience sample of specimens were cultured and underwent molecular characterization. Mortality data was obtained via vital statistics databases and medical chart abstraction. Hospitalization within 2 days before to 7 days of diagnosis was collected.
We identified 9189 incident CDI cases between 2011-2016. The CDI incidence decreased from 241 in 2011 to 175 cases per 100,000 persons in 2016, with the largest decrease among older adults aged ≥85 years. Similarly, the 30-day mortality rates decreased, with the largest decrease among persons aged ≥85 years: from 310 cases to 169 cases per 100,000 population (Figure 1). The percentage of isolates due to NAP1/027 decreased from 20.3% in 2011 to 6.5% in 2016. There was no decrease in the proportion of cases that died within 7 (range: 2% to 3%) and 30 days (range: 7% to 8%) and no decrease in the proportion of patients hospitalized after their CDI diagnosis (range: 34% to 40%). These findings are similar in persons aged ≥85 years.
From 2011 to 2016, the CDI incidence and mortality decreased concurrently with a decrease in the percentage of infections due to the NAP1/027 strain. Although NAP1/027 is known to be associated with more severe outcomes, we did not observe a reduction in the proportion of cases that died or the proportion of cases that were hospitalized.
Figure 1: Incidence and Mortality Rates of CDI
D. Nelson, None
C. B. Felsen, None
G. Dumyati, Seres: Scientific Advisor , Consulting fee .