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Frequent reprocessor filter changes stopped M. avium pseudo-outbreak

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December 3, 2018

Increasing the frequency of filter changes from quarterly to monthly in automated endoscope reprocessors stopped a pseudo-outbreak of Mycobacterium avium in an outpatient bronchoscopy clinic, researchers said.

“Inadequate high-level disinfection or sterilization of bronchoscopes can result in contaminated bronchoalveolar lavage (BAL) fluids or transmission of opportunistic pathogens that cause colonization or infection of susceptible patients,” Jessica L. Seidelman, MD, an infectious disease fellow at Duke University School of Medicine, and colleagues wrote in Infection Control & Hospital Epidemiology. “Nontuberculous mycobacteria are ubiquitous in the environment, prone to form biofilms, and resistant to most disinfectants including chlorine, which make them well suited to cause outbreaks.”

Seidelman and colleagues documented an increase of positive M. avium complex (MAC) BAL samples at Duke Clinic, an outpatient clinic operated by Duke University Hospital that performs a monthly average of 143 bronchoscopies and holds three automated endoscope reprocessors (AERs) in its reprocessing area. Seidelman and colleagues said the number of AERs, as well as the water source, was constant throughout the study.

For the investigation, they reviewed mycobacterial culture data, inspected the bronchoscopy clinical and reprocessing areas and collected environmental samples in the bronchoscope reprocessing area. According to the report, they assessed the total percentage of positive MAC BAL isolates from January 2014 to June 2017 and compared prevalence rates from different time periods. They determined the baseline period as being from Jan. 1, 2014, through June 30, 2015, the outbreak period as July 1, 2015 to Feb. 28, 2016, and the post-outbreak period as March 1, 2016, through June 30, 2017.

The clinic performed 2,238 bronchoscopy procedures during the baseline period and 1,133 during the pseudo-outbreak period, according to the study. During baseline, positive MAC BAL cultures resulted from 5% (n = 112) of the procedures compared with 15% (n = 173) during the pseudo-outbreak (P < .0001). According to the study, 40% (n =34) of unique patients with positive specimens were started on therapy during baseline and 13% (n = 23) during the pseudo-outbreak (P < .0001). However, among patients with positive cultures during the pseudo-outbreak, no definite development of symptomatic MAC infections was identified during the 6-month follow-up period.

Samples taken from multiple bronchoscopes and all three AERs revealed MAC-positive BAL cultures, according to Seidelman and colleagues. Although the researchers did not identify major deficiencies in reprocessing, storage or handling of bronchoscopes, they reported observing an abrupt decline in positive cultures after the AER rinse water filters were changed. Moreover, positive cultures gradually increased over the following 2 months before the next filter change. This led to a change in the frequency of filter changes from quarterly — as recommended by the manufacturer — to monthly. After changing the filter schedule, Seidelman and colleagues observed a decrease in the monthly prevalence of MAC BAL to 3%, below baseline rates.

“We hypothesize that increased procedure volume at our clinic led to increased flow volume through the filters, which resulted in their early failure,” Seidelman and colleagues wrote. “Health care facilities performing high-volume endoscopy procedures should be aware that AER filters may require replacement based on frequency of use or water quality rather than manufacturers’ recommendations based on time in use.” – by Marley Ghizzone

Disclosures: The researchers report no relevant financial conflicts.

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