The results of two studies published in the renowned medical journal The New England Journal of Medicine show that bronchoscopic examinations and manipulations can cause outbreaks of nosocomial infection in patients Pseudomonas aeruginosa .

An epidemiological investigation revealed constructive and manufacturing defects in endoscopic equipment, in particular a violation of the tightness of the plug of the biopsy orifice. As a result, microorganisms entered the device and, in addition, the effectiveness of disinfection of bronchoscopic material was greatly reduced (P.aeruginosa remained viable after three standard treatment cycles with orthophthalaldehyde).

Both studies analyzed patient medical records, the results of a microbiological study of clinical material obtained from patients, and samples taken from a bronchoscopy machine to detect cases of infections that occurred within 2 to 4 weeks after the procedure. In a study, the typing of P.aeruginosa isolates was carried out by pulsed gel electrophoresis (PFGE) to compare the characteristics of strains isolated from patients and found on bronchoscopic devices.

In addition, when conducting an epidemiological investigation of outbreaks, the technology for performing bronchoscopic procedures and the effectiveness of automatic endoscope processing systems were verified.

In these studies, data from two clinics of approximately 60 and 414 patients were analyzed, in which 66 and 665 bronchoscopies were performed, respectively.

According to D.L. Kirschke et al. 43 microbiological studies of clinical material were carried out in patients of the first clinic, P.aeruginosa was found in 20 samples (47%), of which 6 also contained S.marcescens .

The second clinic, Johns Hopkins Hospital in Baltimore (United States), showed a threefold increase in the frequency of nosocomial infections caused by P.aeruginosa compared to the reference value (of 10.4% to 31.0%). In 97 patients (23%), Pseudomonas aeruginosa was found in samples of clinical material. By typing the isolates with PFGE, it was found that the strains isolated from the patients are identical to those obtained from the surfaces of the bronchoscopes, including from the biopsy port.

It was noted that P.aeruginosa contamination was observed using certain models of new modification bronchoscopes (BFIT160, BF160, BFP40, Olympus America). At the same time, contamination indicators for endoscopes from other models, including the gastrointestinal tract examining equipment, were within acceptable limits. In addition, it was found that by stopping the use of the devices of the new modifications listed, the frequency of nosocomial infections caused by Pseudomonas aeruginosa returned to the baseline.

Despite the fact that there was no violation of the technology for performing bronchoscopic procedures and subsequent disinfection of the material, strains of P. aeruginosa were constantly found in the smears taken from the surfaces of the biopsy ports of the bronchoscopes. It turned out that the new models of bronchoscopes received by clinics were distinguished by a violation of the tightness of the heel of the biopsy port. As a result, the microorganisms entered the device and then did not get eradicated during the treatment of the device, because the air plugs in the cavity of the orifice prevented the disinfectant from touching properly the surface and dry the cavity of the device at the final stage of treatment.

Continuous contamination of P.aeruginosa bronchoscopes has led not only to patient infection, but also to false positive results from bacteriological studies, to the erroneous recording of an outbreak of Pseudomonas aeruginosa nosocomiale and an unreasonable prescription of antibiotic therapy. However, during the initial infection of patients during the bronchoscopic procedure, antibiotic therapy prevented the development of a nosocomial infection.

The data obtained led to the withdrawal of approximately 14,000 models of bronchoscopes already used for their development, as well as the active search for suitable methods to test new medical equipment before introducing them into clinical practice.