2016 Annual Report for the Emerging Infections Program for Clostridium difficile Infection

2016 Annual Report Print Version [PDF – 2.41 MB]

In 2016, a total of 16,796 cases of C. difficile infection (CDI) were reported to the Emerging Infections Program (EIP) in 35 counties in 10 US states (California, Colorado, Connecticut, Georgia, Maryland, Minnesota, New Mexico, New York, Oregon, and Tennessee).

The overall distribution of EIP CDI cases and crude incidence by selected demographic factors and epidemiologic classification are presented in Table 1. Data in this report are not intended to be directly compared to annual reports from other years, and should not be used to determine annual changes in EIP CDI incidence rates because single year calculations do not account for changes in testing practices by reporting facilities.

Table 1. Reported Number of CDI Cases and Crude Incidence by Sex, Age Group, Race, and Epidemiologic Classification Among the 10 EIP Sites^a

1. The epidemiologic classification was statistically imputed for 1.0% of the observed CDI cases, and race was statistically imputed for 17.9% of the observed CDI cases. The weighted frequency of cases in Colorado and Georgia was based on 33% random sampling for cases aged ≥18 years.
2. A CDI case was classified as community-associated if the C. difficile-positive stool specimen was collected on an outpatient basis or within 3 days after hospital admission in a person with no documented overnight stay in a healthcare facility in the preceding 12 weeks. All CDI cases that do not meet the aforementioned criteria were classified as healthcare-associated.
3. Cases per 100,000 persons.

Laboratory Characterization of C. difficile Isolates

In 2016, 969 C. difficile isolates were submitted to CDC for further analysis. The total number of isolates received from each site ranged from 26 to 278, with a median of 75.5. The majority of the isolates (97%) were collected in metropolitan areas.

Among all isolates submitted, 138 distinct ribotypes were detected. Ribotype 106 was the most common ribotype among community-associated C. difficile isolates, followed by 027, 002, and 014 (Table 2). Among healthcare-associated C. difficile isolates, ribotype 027 predominated, followed by 106, 014 and 020 (Table 3).

The prevalence of ribotype 027 among healthcare-associated C. difficile isolates was lower in 2016 (16%) than in 2015 (19%), although this difference was not statistically significant (p=0.25). Ribotype 027 remained relatively stable among community-associated C. difficile isolates between 2015 (8%) and 2016 (9%). In contrast, the prevalence of ribotype 106 among community-associated C. difficile isolates was higher in 2016 (13%) than in 2015 (9%), although this difference also was not statistically significant (p=0.08).

Twenty-six percent of the isolates harbored a deletion in tcdC. Twenty-six percent of the isolates were binary toxin-positive, and among these, ribotypes 027, 019, and 078 predominated.

Table 2. Frequency of Ribotypes Among Community-Associated C. difficile Isolates, 2016 (n=460)

1. Percentages may not add to 100% due to rounding.

Table 3. Frequency of Ribotypes Among Healthcare-Associated C. difficile Isolates, 2016 (n=509)

1. Percentages may not add to 100% due to rounding.