CDC Reports Sharp Increase in Candidemia Among Injection Drug Users

Cases of candidemia associated with injection drug use are on the rise, according to a recent study by the US Centers for Disease Control and Prevention (CDC), suggesting that the opioid crisis and increases in heroin use are shifting the landscape for these infections.

The study, published in Clinical Infectious Diseases, involved surveillance of 9 states during 2017. Investigators identified 1191 cases of candidemia, including 128 (10.7%) among injection drug users (IDU). Among patients ages 19-44 years, the proportion of candidemia involving injection drug users was 34.6%.

“We found that the proportion of candidemia cases associated with injection drug use rose nearly three-fold during 2014-2017, which likely reflects the rise in injection drug use due to the nation’s opioid crisis,” Snigdha Vallabhaneni, MD, MPH, medical epidemiologist at the CDC, told Contagion^®. “Nearly 1 in 8 patients with candidemia had a recent history of injection drug use. Doctors usually think of Candida bloodstream infections (candidemia) as something that only affects people who have spent a long time in the intensive care unit, undergone major abdominal surgery or have cancer. Although injection drug use is a known risk factor for candidemia, we are now beginning to understand the extent to which injection drug use contributes to candidemia.”

The study included 167 hospitals and 97 labs in California, Colorado, Georgia, Maryland, Minnesota, New Mexico, New York, Oregon and Tennessee. The proportion of candidemia cases involving IDU was lowest in Minnesota at 1.4% and highest in New Mexico at 32.3%. Overall, the proportion of cases involving IDU rose from 6.9% in 2014 to 15.2% in 2017, with the greatest increase occurring in Tennessee, with a near tripling from 6.5% to 18.2%.

Vallabhaneni said health care practitioners should consider injection drug use as a possible risk factor for candidemia.

“When you see a young patient with candidemia and none of the typical, well-known risk factors, such as cancer, abdominal surgery, organ transplantation, etc, think about injection drug use as an underlying risk factor,” he said. “If present, look for other infectious disease sequelae of injection drug use, such as HIV, hepatitis B and C, and bloodstream and heart valve infections with bacteria such as methicillin-resistant Staphylococcus aureus (MRSA). It is also important to offer treatment programs for substance use and provide harm reduction resources. Candidemia no longer only occurs in the very old patients who spent a lot of time in the intensive care unit.”

The study found that candidemia cases associated with IDU were more likely to include patients with hepatitis, HIV and homelessness and less likely to involve diabetes or malignancies. The study also found some differences in the species of Candida identified, with C glabrata less common among IDU cases. IDU cases were associated with shorter hospital stays and lower mortality, with possibly factors including younger age and fewer comorbidities or greater likelihood of leaving the hospital against medical advice. IDU cases were twice as likely to have polymicrobial blood cultures, including Enterococcus faecium and E faecalis, Acinetobacter baumannii Staphylococcus, Serratia marcescens and Stenotrophomonas maltophilia.

Unclean injection practices can introduce yeast into the bloodstream, and hospitalizations for IDU-related events also could increase the risk of infection.

“We are exploring ways to improve our understanding of this seemingly widespread phenomenon of injection drug use-associated candidemia,” Vallabhaneni told Contagion^®. “We want to know how these patients get infected, and what their outcomes are when this happens so that we can figure out ways to prevent infections and provide effective treatment.”

Candidemia is the 4^th most common health care-associated infection, raising interest in improving outcomes through such measures as having infectious disease physicians consulting on patients with fungal infections. Faster diagnoses through dual DNA barcoding also has been explored to improve outcomes.