Population-Based Active Surveillance for Culture-Confirmed Candidemia — Four Sites, United States, 2012–2016

PROBLEM/CONDITION Candidemia is a bloodstream infection (BSI) caused by yeasts in the genus Candida. Candidemia is one of the most common health care-associated BSIs in the United States, with all-cause in-hospital mortality of up to 30%. PERIOD COVERED 2012-2016. DESCRIPTION OF SYSTEM CDC's Emerging Infections Program (EIP), a collaboration among CDC, state health departments, and academic partners that was established in 1995, was used to conduct active, population-based laboratory surveillance for candidemia in 22 counties in four states (Georgia, Maryland, Oregon, and Tennessee) with a combined population of approximately 8 million persons. Laboratories serving the catchment areas were recruited to report candidemia cases to the local EIP program staff. A case was defined as a blood culture that was positive for a Candida species collected from a surveillance area resident during 2012-2016. Isolates were sent to CDC for species confirmation and antifungal susceptibility testing. Any subsequent blood cultures with Candida within 30 days of the initial positive culture in the same patient were considered part of the same case. Trained surveillance officers collected clinical information from the medical chart for all cases, and isolates were sent to CDC for species confirmation and antifungal susceptibility testing. RESULTS Across all sites and surveillance years (2012-2016), 3,492 cases of candidemia were identified. The crude candidemia incidence averaged across sites and years during 2012-2016 was 8.7 per 100,000 population; important differences in incidence were found by site, age group, sex, and race. The crude annual incidence was the highest in Maryland (14.1 per 100,000 population) and lowest in Oregon (4.0 per 100,000 population). The crude annual incidence of candidemia was highest among adults aged ≥65 years (25.5 per 100,000 population) followed by infants aged 18 years, 34% were treated with fluconazole alone, 30% with echinocandins alone, and 34% with both. The all-cause, in-hospital case-fatality ratio was 25% for any time after admission; the all-cause in-hospital case-fatality ratio was 8% for <48 hours after a positive culture for Candida species. Candida albicans accounted for 39% of cases, followed by Candida glabrata (28%) and Candida parapsilosis (15%). Overall, 7% of isolates were resistant to fluconazole and 1.6% were resistant to echinocandins, with no clear trends in resistance over the 5-year surveillance period. INTERPRETATION Approximately nine out of 100,000 persons developed culture-positive candidemia annually in four U.S. sites. The youngest and oldest persons, men, and blacks had the highest incidences of candidemia. Patients with candidemia identified in the surveillance program had many of the typical risk factors for candidemia, including recent surgery, exposure to broad-spectrum antibiotics, and presence of a CVC. However, an unexpectedly high proportion of candidemia cases (10%) occurred in patients with a history of injection drug use (IDU), suggesting that IDU has become a common risk factor for candidemia. Deaths associated with candidemia remain high, with one in four cases resulting in death during hospitalization. PUBLIC HEALTH ACTION Active surveillance for candidemia yielded important information about the disease incidence and death rate and persons at greatest risk. The surveillance was expanded to nine sites in 2017, which will improve understanding of the geographic variability in candidemia incidence and associated clinical and demographic features. This surveillance will help monitor incidence trends, track emergence of resistance and species distribution, monitor changes in underlying conditions and predisposing factors, assess trends in antifungal treatment and outcomes, and be helpful for those developing prevention efforts. IDU has emerged as an important risk factor for candidemia, and interventions to prevent invasive fungal infections in this population are needed. Surveillance data documenting that approximately two thirds of candidemia cases were caused by species other than C. albicans, which are generally associated with greater antifungal resistance than C. albicans, and the presence of substantial fluconazole resistance supports 2016 clinical guidelines recommending a switch from fluconazole to echinocandins as the initial treatment for candidemia in most patients.