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229 Investigation of a cluster of Acremonium- and Lecanicillium-positive clinical cultures from orthopedic patients — Colorado, 2008-2009

Friday, March 19, 2010
Grand Hall (Hyatt Regency Atlanta)
Loretta Sullivan Chang, MD, MPH , Centers for Disease Control and Prevention, Atlanta, GA
Heather Gilmartin, RN, MSN , Denver Health and Hospital Authority, Denver, CO
Elissa Meites, MD, MPH , Centers for Disease Control and Prevention, Atlanta, GA
Maho Imanishi, BA , Centers for Disease Control and Prevention, Atlanta, GA
Connie S. Price, MD , Denver Health Medical Center, Denver, CO
S. Arunmozhi Balajee, PhD , Centers for Disease Control and Prevention, Atlanta, GA
Benjamin J. Park, MD , Centers for Disease Control and Prevention, Atlanta, GA
Judith Noble-Wang, PhD , Centers for Disease Control and Prevention, Atlanta, GA
Carol Rao, PhD , Centers for Disease Control and Prevention, Atlanta, GA
Shelley Magill, MD, PhD , Centers for Disease Control and Prevention, Atlanta, GA
Tom Chiller, MD, MPH , Centers for Disease Control and Prevention, Atlanta, GA
Background: Acremonium is an environmental mold that occasionally causes serious disease in immunocompromised hosts. In April 2009, the Colorado Department of Public Health and Environment notified CDC of six cases of possible Acremonium infection occurring between October 2008 and April 2009 among patients undergoing orthopedic procedures at Hospital A.

Objective: To identify potential sources and risk factors for developing Acremonium in clinical samples, and to make recommendations for preventing future cases.

Methods: We conducted environmental and case-control studies. Cases were patients with intraoperative cultures positive for mold identified as Acremonium between August 2008 and April 2009; controls were patients with intraoperative cultures negative for Acremonium. We observed infection control practices and tested air pressure differentials in operating rooms. We collected environmental samples from the operating suite and clinical specimen processing areas at Hospital A and the commercial laboratory that processed all Hospital A fungal cultures. Acremonium isolates were confirmed and subtyped by molecular methods.

Results: The commercial laboratory identified Acremonium in six tissue samples from Hospital A; all six (100%) had been collected during irrigation and debridement (I&D) procedures conducted in an operating suite. All case-patients improved clinically without antifungal treatment. Twenty control patients who had undergone other orthopedic procedures were enrolled in a case-control study. I&D was significantly more common among cases than controls (OR=95; 95% confidence interval= 3.6-15,000). Air pressure differential testing showed that positive pressure was not maintained in all operating suites. Isolates from three case-patients were available for examination; molecular identification revealed that isolates from two case-patients were not Acremonium as originally reported, but rather Lecanicillium, a morphologically similar fungal genus that has never been reported as a human pathogen. Acremonium was recovered from one environmental culture of a decorative plant in the hospital laboratory.

Conclusions: This investigation, the first reported cluster of Acremonium/Lecanicillium species in human clinical samples, suggested that this was a pseudo-outbreak due to contamination during collection and/or processing for culture. Molecular methods were essential to differentiate between an opportunistic organism and a non-human pathogen. Removing decorative plants from laboratories, establishing appropriate operating suite airflow, and maintaining attention to routine infection control measures during tissue specimen collection and processing may help limit further cases.