Assessing Risk Factors for Infection with Carbapenem-Resistant Enterobacteriaceae

Jan. 12, 2018

Infections with carbapenem-resistent Enterobacteriaceae, or CRE, are a growing concern in the clinic. CRE encompass a wide range of bacterial types, including Klebsiella pneumoniae and Escherichia coli, that frequently cause both superficial and life-threatening disease. Hospital and long-term care patients are particularly susceptible to infections with CRE. A new systematic review of literature, published in Antimicrobial Agents and Chemotherapy, looks through previous studies to answer the question: what are the risk factors for a CRE infection?

AAC Journal: A systematic review and meta-analyses of the clinical epidemiology of carbapenem-resistent Enterobacteriaceae.

To answer this, scientists Karlijn van Loon, Anne Voor in ‘t holt, and Margreet Vos examined the literature to find studies on CRE from around the world. The team found that use of antibiotics, including carbapenems, cephalosporins, and glycopeptides, was strongly associated with risk of CRE infection. Both carbapenems and cepholosporins act on the bacterial cell wall, and cepholosporin use has been suggested to select for carbapenem resistance. The association between using antibiotics and selecting for resistant bacteria is well documented, and the finding by the team in this study confirms this link.

Risk factors not associated with antibiotic use were also examined. Underlying disease, which can make one susceptible to secondary infection, was the most frequently identified risk factor in different studies. However, the factors that were found to put patients at highest risk were medical devices, invasive procedures, and admission to the intensive care unit. Use of medical devices or invasive procedures increases the risk of exposing patients to their own microbiota, which can harbor CRE organisms.

A list of ten ways to control hospital outbreaks with CRE
Top 10 strategies to control hospital outbreaks with CRE. Source.

The researchers also assessed the best infection prevention strategies, with barrier and/or contact precautions found to be the most effective way to control the spread of CRE within a hospital. Isolating at-risk patients from others, a practice called patient cohorting, and active surveillance were also consistently found to be effective. While only a few studies investigated the environmental sources that may act as reservoirs of CRE within their hospitals, the most frequently described sources were contaminated sinks, patient beds, and mechanical ventilation equipment.

The types of systematic meta-analyses performed in this study are a vital part of the scientific process. By comparing results of many different studies, the authors ensure the most robust and repeatable experimental results can translate into actionable information. In this case, the identification of medical devices as a major risk factor for disease may lead health care workers to increase surveillance of patients treated with these devices or to increase prophylaxes for particularly vulnerable patients.

Author: Julie Wolf

Julie Wolf
Dr. Julie Wolf is in science communications at Indie Bio, and was a former ASM employee. Follow Julie on Twitter for more ASM and microbiology highlights at @JulieMarieWolf.