Pseudomonas aeruginosa, a bacterium known for its ability to adapt and resist antibiotics even during a course of treatment, is responsible for nine percent of hospital-acquired infections. This bacterium is also one of the most common organisms found on contaminated endoscopes.
The threats posed by P. aeruginosa to bronchoscopy patients are varied in nature but should be taken seriously because antimicrobial-resistant bacteria are getting more costly and difficult to treat. Of the estimated 51,000 healthcare-associated P. aeruginosa infections reported each year, approximately 13 percent of them are caused by a multidrug-resistant strain.
According to the CDC, multidrug-resistant Pseudomonas can be deadly for patients in critical care. The CDC attributes approximately 400 deaths each year to infections caused by this bacterium.
Creating a ‘vicious circle’
P. aeruginosa is the most common strain of Pseudomonas to infect people, according to the CDC. These infections usually occur in the hospital and can be spread on the hands of healthcare workers or by contact with a contaminated medical device.
An estimated 500,000 bronchoscopies are performed annually so the risks of infection are relatively low. Research, however, suggests the true rate of infection transmission during endoscopy is vastly underreported due to poor surveillance or the absence of clinical symptoms.
Since multidrug-resistant bacteria are so difficult to treat, any risk of infection, especially by resistant bacteria, can be a significant cost and burden to a hospital.
One of the ways P. aeruginosa can survive from one bronchoscopy to the next, despite even a reprocessing procedure, is in the presence of a biofilm.
Biofilm, once formed, is particularly difficult to remove from the long, narrow channels of a flexible scope. It is also a hotbed for bacterial growth, according to the 2013 study, “Transmission of Infection by Flexible Gastrointestinal Endoscopy and Bronchoscopy.”
In the study, authors Julia Kovaleva, Frans T.M. Peters, Henny C. van der Mei, and John E. Degener point out that biofilm “allows microorganisms to survive under conditions of drying and chemical and antibiotic exposure.”
“Biofilm formation on the inner surface of endoscopy channels, especially when these become scratched or damaged, can result in failure of the decontamination process,” the authors write. “It can create a vicious circle of growth, disinfection, partial killing or inhibition, and regrowth, resulting in outbreaks of endoscopy-related infections in patients who underwent endoscopy with a biofilm-containing endoscope.”
Since biofilm can form so easily on flexible bronchoscopes, infectious agents like P. aeruginosa pose a grave risk to patients.
A long and arduous process
In addition to proper handwashing procedures, healthcare professionals in the OR and ICU can take several steps to help curb the spread of this bacterium from device to patient.
Infection prevention via antibiotic prophylaxis is not generally recommended for flexible bronchoscopy. Rather, infection prevention falls to proper cleaning and maintenance of flexible bronchoscopes.
At least three patient deaths were believed to have been caused by an infection of P. aeruginosa transmitted via a contaminated bronchoscope at Johns Hopkins Hospital between June 2001 and January 2002.
In a 2003 study, “An Outbreak of Pseudomonas aeruginosa Infections Associated with Flexible Bronchoscopes,” researchers concluded that three bronchoscopes, which had been subject to a recall, were the culprits behind the P. aeruginosa outbreak. Of the 414 patients that underwent a bronchoscopy during the studied time, 48 infections were reportedly linked to the bronchoscopes. P. aeruginosa was the infecting agent for 66.7 percent of the infections.
Researchers found that infection rates improved once the three recalled bronchoscopes were removed from use. The scopes had been recalled due to a loose biopsy-port cap, according to the report.
Like the 2001–2002 case, many infection outbreaks after bronchoscopies have been linked back to broken devices. Routine maintenance is required on flexible endoscopes to reduce the risk of cross-contamination.
In addition to equipment malfunction, inadequate decontamination, drying and storage procedures are also to blame for device-related cross-contamination.
“Many outbreaks of health care-associated infection after endoscopy and cross-contaminations due to P. aeruginosa, S. marcescens, M. tuberculosis, and M. chelonae have been associated with drying of flexible endoscopes without ethanol flushing or lack of a drying procedure,” according to Kovaleva, et al.
Outbreaks have even been traced back to rinsing flexible endoscopes with nonsterile tap water.
In a 2016 outbreak of P. aeruginosa, a connecting tube was causing rinse water that was flushing disinfected bronchoscopes to be contaminated, subsequently re-contaminating the bronchoscopes. After the connecting tube was replaced, the instances of reported P. aeruginosa stopped.
Reprocessing a flexible bronchoscope is a long and arduous process. Constant attentiveness and vigilance are needed to help prevent infections like those caused by multidrug-resistant P. aeruginosa.
For more information about flexible bronchoscope reprocessing guidelines, please visit www.bedsidebronchoscopy.com/guidelines.