Article courtesy of Sarah Wickline Wallan | October 10, 2015 | MEDPAGETODAY | Shared as educational material
Lung Infection Outbreak Linked to Hospital – Hospital had to institute special measures to stem outbreak
SAN DIEGO — A Mycobacterium abscessus outbreak among lung transplant patients at a single hospital was traced to new building construction and its tainted water supply, researchers reported here.
M. abscessus infections were confirmed in 39 recently hospitalized lung transplant patients, the source of which was traced to 12 tap water supply locations in the ward, prompting the use of sterile water and a new antibiotic prophylaxis regimen, including imipenem and inhaled amikacin, to manage the outbreak, Arthur W. Baker, MD, MPH, of Duke University, and colleagues presented at IDWeek.
“A new medical tower that had largely ICU beds and began to serve patients in late 2013…lead to an amplification event where the concentration of M. abscessus grew past a certain threshold, but those isolates were present before the construction and opening of the building,” Baker said at IDWeek — the joint meeting of four medical organizations with an interest in infectious illness — the Infectious Diseases Society of America (IDSA), the HIV Medicine Association (HIVMA), the Society for Healthcare Epidemiology of America (SHEA), and the Pediatric Infectious Diseases Society (PIDS).
“Mycobacterium abscessus, and all rapid growing mycobacteria, can be problematic for hospitals, because they’re ubiquitous in the environment. They’re in the soil, they’re in the water supply, and I think it’s always a concern when you’re building a new building — potential contamination of the water to patients who could be at risk to acquire infections,” Kimberly Hanson, MD, of the University of Utah, who was not affiliated with the study, said in an interview with MedPage Today. “I think it’s something hospitals should consider and physicans should be aware of and alert to that new cases of environmental organisms in their compromised host could signal hospital outbreak.”
From August 2013 through May 2014, the incidence rate was 3.9 cases per month, but that rate dropped back down to an average of 1.0 cases per month after the implementation of intervention in June 2014 through March 2015 (incidence rate ratio 0.26, 95% CI 0.13-0.51, P<0.0001).
In 92% of the patients, M. abscessus was first isolated in the respiratory tract.
During the investigation for the source of the contaminant, the researchers determined that there was no evidence of a pseudo-outbreak in the microbiology lab, or contamination of the bronchoscopes or bronchoscopy suite.
The researchers took cultures from environmental biofilms from 73 water sources in the hospital. These included patient room faucets and shower heads, ward faucets, and ice machines. Out of those 73 source environmental cultures, 12, or 16%, grew M. abscessus.
In all 12 of the environmental isolates, and 10 of the 13 clinical isolates, a unique genotypic profile — type VI erm gene and C — >T mutation at base pair 207 of the rpoß gene was identified.
Four of the 10 clinical isolates, and eight of the 12 environmental isolates, were indistinguishable by pulsed-field gel electrophoresis (PFGE) analysis.
And a new antibiotic prophylaxis regimen of imipenem and inhaled amikacin was implemented, which lowered the incidence rate from 4.2 cases per month to 0.9 cases per month (incidence rate ratio, 0.2, 95% CI 0.1-0.4, P<0.001). Baker said that this was a return to the pre-outbreak incidence rate.
The hospital also made engineering changes to the new medical tower to decrease concentration of M. abscessus at the hospital tap water outlets, Baker said.
Baker said that a limitation to the study was the inability to determine the relative impact of sterile water protocol and perioperative antibiotic changes, as they were introduced simultaneously.
Reviewed by F. Perry Wilson, MD, MSCE Assistant Professor, Section of Nephrology, Yale School of Medicine and Dorothy Caputo, MA, BSN, RN, Nurse Planner