An outbreak of Pseudomonas aeruginosa infections associated with flexible bronchoscopes.

Abstract

Comments: This retrospective report investigated an outbreak of Pseudomonas aeruginosa infections after bronchoscopic procedures at a major medical center. The Journal of Bronchology medical center where these infections occurred is a 1,000-bed tertiary care hospital, where approximately 1,000 flexible bronchoscopic procedures are performed annually, and approximately 65% of these procedures include bronchoalveolar lavage (BAL). The investigation was undertaken because the rate of recovery of P. aeruginosa from BAL effluents obtained with use of endoscopy suite bronchoscopes increased from 10.4% at baseline to 31% during the outbreak (relative risk, 2.97; 95% confidence interval, 2.28 to 3.90). A total of 414 patients underwent 665 bronchoscopic procedures during the outbreak. There were 48 infections among 39 of the 414 patients (9.4%) during the 2 weeks after bronchoscopy (7.2% of procedures), including 28 cases of pneumonia, 7 cases of bronchitis, 6 cases of sinusitis, 3 cases of lower respiratory tract infection, and 4 bloodstream infections. During the outbreak, 97 patients (23.4%) had a BAL culture that grew P. aeruginosa. During this period, P. aeruginosa was isolated from a respiratory specimen in 21 patients (5.1%) before they underwent bronchoscopy, and 35 patients (8.5%) had a subsequent culture of a respiratory tract specimen, not obtained by BAL, that grew P. aeruginosa. Of the 414 patients, 101 (24.4%) returned for a follow-up evaluation. Eight had a sputum culture that grew P. aeruginosa, but PFGE demonstrated that only one of the organisms was related to a strain recovered from a bronchoscope. The study included review of microbiologic results to determine the rates of recovery of P. aeruginosa from BAL specimens, collection of environmental samples for culture from endoscopes and the endoscopy suite, and review of medical records to identify infections in the 14 days after a bronchoscopy. The results from the study showed that cultures of samples from three bronchoscopes grew P. aeruginosa, whereas cultures of samples from the environment, instrument-cleaning machines, and gastrointestinal endoscopes did not. The three bronchoscopes had been part of a nationwide recall. A total of 414 patients underwent bronchoscopy during the outbreak, and there were 48 respiratory tract and bloodstream infections among 39 of these patients (9.4%). In 32 infections (66.7%), P. aeruginosa was confirmed as a potentially causative organism. There were no significant differences in the frequency of risk factors for P. aeruginosa infection (immunosuppression, mechanical ventilation, or cystic fibrosis) between patients undergoing BAL during the baseline period and those undergoing the procedure during the outbreak period. The authors opine that exposure to a potentially contaminated bronchoscope may have had a role in the death of three patients. The rate of recovery of P. aeruginosa returned to baseline after the instruments were removed from service. The authors concluded that a loose biopsy port cap in the bronchoscopes apparently caused this large outbreak of P. aeruginosa infections related to bronchoscopy. They also conclude that instrument safety and surveillance methods for bronchoscopy must be improved, and better recall procedures are needed for medical devices. Considering that more than 500,000 bronchoscopic procedures are performed each year in the United States, the potential for contamination of the bronchoscopes is enormous, if proper cleaning and sterilization procedures are not adhered to. The rigid bronchoscope and ancillary equipment can be subjected to the highly effective standard autoclave-sterilization process. However, the autoclave procedure cannot used to sterilize the flexible bronchoscope because the process easily damages the flexible bronchoscope. Routine use of ethylene oxide to sterilize the flexible bronchoscope is impractical because ethylene oxide reprocessing requires an inordinate amount of time. Most flexible bronchoscopes are therefore subjected to thorough cleaning and high-level disinfection. Improper cleaning and disinfecting procedures have led to several bronchoscopy-related outbreaks and pseudooutbreaks of P. aeruginosa and S. marcescens infections. However, when published guidelines are strictly implemented, high-level disinfection can be ensured. It should be noted that in the first report, the hospital's reprocessing procedures were determined to be satisfactory. The cause of these infections and pseudoinfections were the result of the manufacturer's failure to conform to production standards, which resulted in the distribution of bronchoscopes that did not meet manufacturing specifications. In the first report, inspection of bronchoscopes revealed that the caps of the biopsy ports were not securely fastened and were easily removable, contrary to manufacturing specifications. When the threads of the biopsy ports and the inside of the caps of bronchoscopes were swabbed, a dark-green film was noted, and 9 of 12 swab specimens were positive for P. aeruginosa and S. marcescens. The other three swab specimens were positive for P. aeruginosa alone. PFGE patterns linked the P. aeruginosa isolates from the patients to the isolates from the bronchoscopes. After this study was completed, the manufacturer of the bronchoscopes initiated a recall of 15 models of bronchoscopes, including the 2 models implicated in the investigation. In this report, the bronchoscopists subsequently learned that the contaminated bronchoscopes were subject to a national recall, issued in November 2001, because of “a customer complaint regarding a loosened bronchoscope biopsy port and microbial contamination of the port.” In the case of this recall, the manufacturer initially sent letters to facilities in which the bronchoscopes were used. When the initial effort was not sufficient, letters were subsequently sent to individual physicians. After this information became available, the bronchoscopists examined the biopsy ports of the contaminated bronchoscopes and found that all were loose. In both reports, the contamination appeared to be related to a loose biopsy port cap on the bronchoscopes, which may have sheltered organisms and thus rendered disinfection procedures ineffective. The lessons from these important publications include the following points: The manufacturer of bronchoscopes and ancillary instruments should establish better recall procedures. Multiple recalls should be instituted quickly if the first recall fails to elicit a dramatic number of responses. The manufacturers should continue to improve safety aspects of instruments. The bronchoscopist and bronchoscopy team should report malfunctioning of medical devices to the manufacturer. The bronchoscopist and bronchoscopy team should follow all cleansing and disinfecting instructions from the manufacturer. The bronchoscopist and bronchoscopy team (and the medical center where bronchoscopy is practiced) should establish surveillance procedures to identify increases in rates of bacterial identification from bronchoscopy specimens.