Guest bloggers Dr. Rossana Rosa and Dr. Silvia Munoz-Price (bios below) write…

In everyday practice of those of us who work in intensive care units, a scenario frequently arises: a patient has a surveillance culture growing carbapenem-resistant Acinetobacter baumannii (CRAB). While the ultimate course of action we take will be dictated by the patient’s clinical status, that surveillance culture, in the appropriate context, can provide us with valuable information.

For this study¹, we looked at a cohort of patients admitted to a trauma intensive care unit, and sought to identify the risk factors for CRAB infections. We found that patients who had surveillance cultures positive for CRAB had a hazard ratio of 16.3 for the development of clinical infections with this organism, compared to patient’s who remained negative on surveillance, even after adjusting for co-morbidities and antibiotic exposures. Since our results were obtained as part of a well-structured surveillance program, we know that colonization preceded infection.  Unfortunately for some of our patients, the time from detection of colonization to development of clinical infections was a matter of days. With therapeutic options for the effective treatment of infections with CRAB limited to tigecycline and polymixins, the consequences of delaying therapy are often fatal. As described by Lee et al, a delay of 48 hour in the administration of adequate therapy for CRAB bacteremia can result in a 50% difference in mortality rate².

Surveillance cultures are not perfect, and may not detect all colonized patients, but they can be valuable tools in the implementation of infection control strategies³, and as we found in our study, can also potentially serve to guide clinical decision that impact patient care and even survival.

Bio:

Dr. Silvia Munoz-Price (centre left) is an Associate Professor of Clinical Medicine at the Institute for Health and Society, Medical College of Wisconsin, currently serving as the Enterprise Epidemiologist for Froedert & the Medical College of Wisconsin. Dr. Rossana Rosa (centre right) is currently an Infectious Diseases fellow at Jackson Memorial Hospital-University of Miami Miller School of Medicine. She hopes to continue developing her career in Hospital Epidemiology and Infection Control.

References

1. Latibeaudiere R, Rosa R, Laowansiri P, Arheart K, Namias N, Munoz-Price LS. Surveillance cultures growing Carbapenem-Resistant Acinetobacter baumannii Predict the Development of Clinical Infections: a Cohort Study. Clin Infect Dis. Oct 28 2014.
2. Lee HY, Chen CL, Wu SR, Huang CW, Chiu CH. Risk factors and outcome analysis of Acinetobacter baumannii complex bacteremia in critical patients. Crit Care Med. May 2014;42(5):1081-1088.
3. Munoz-Price LS, Quinn JP. Deconstructing the infection control bundles for the containment of carbapenem-resistant Enterobacteriaceae. Curr Opin Infect Dis. Aug 2013;26(4):378-387.

Image: Acinetobacter.