April 10, 2013 — This article discusses bacterial outbreaks linked to flexible endoscopes contaminated with waterborne microorganisms, including bronchoscopes contaminated with Pseudomonas aeruginosa. The importance of drying the endoscope’s channels using a 70% alcohol rinse, followed by forced air is underscored.
Objectives
To review a CDC report and to determine what specific practices may reduce the risk of patient infection caused by or linked to flexible endoscopes contaminated with opportunistic, waterborne microorganisms, including Pseudomonas aeruginosa.
This article is to be read in conjunction with another of Dr. Muscarella’s articles: “Infections of Pseudomonas aeruginosa linked to Flexible Endoscopes,” which can be read by clicking here.
Background
Although well-documented, clinical infections following flexible endoscopy are rare,1-6 and no cases of a flexible endoscope transmitting a disease have been reported when the instrument was reprocessed (ie, pre-cleaned, disinfected, and dried before storage) in accordance with published guidelines. Nevertheless, healthcare-associated infections (HAIs) linked to flexible endoscopes contaminated with infectious microorganisms have been reported.
Read Dr. Muscarella blog “Infections of Pseudomonas aeruginosa linked to Flexible Endoscopes” by clicking here.
The CDC’s findings
In a report by the CDC published in MMWR Weekly (July 9, 1999; click here to read it), the cause of several bronchoscopy-related infections (and pseudo-infections) was investigated.
Click here to learn about a program that Dr. Muscarella designed for healthcare facilities to reduce the risk of infection-control breaches and associated infections.
According to the CDC’s report, improper connection of an automated reprocessor to bronchoscopes precluded effective reprocessing, resulting in multiple patient infections (and possibly one fatality).
Read Dr. Muscarella’s article in Chest “The Importance of Bronchoscope Reprocessing Guidelines: Raising the Standard of Care” by clicking here.
This outbreak’s identified culprits included P. aeruginosa and Mycobacterium avium-intracellulare (MAI), the latter of which is an opportunistic atypical mycobacterium that has been identified in water sources. Indeed, inferring from the CDC’s report that proper connection of the automated reprocessor to the bronchoscopes would have prevented these injuries seems logical enough.
Water as a source?
Noteworthy, although not discussed by the CDC in this MMWR Weekly report of 1999, P. aeruginosa and MAI are waterborne microorganisms that may be present in drinking water6 and have been identified in both filtered and unfiltered water used to rinse medical instruments.1,6-10
Indeed, whenever water used to rinse a flexible endoscope (after its immersion in a chemical disinfectant or sterilant) is contaminated with microorganisms, there is the possibility that the endoscope may become re-contaminated and transmit these microorganisms to the patient (e.g., inadvertently into the patient’s lungs during bronchoscopy), giving rise to an important question confusingly not addressed by the CDC:
During the investigation of the cause of these several bronchoscopy-related infections (and pseudo-infections), was the quality of the healthcare facility’s water supply, or the automated reprocessor’s water filter itself, sampled and analyzed to rule out (or to introduce) the possibility that the filtered rinse water was the source of the microorganisms that infected the patients?
Water sampling
Sampling and culturing the tap water and filtered water used to rinse bronchoscopes during their reprocessing for the purpose of determining, if not excluding, whether it could have been the source of these reported infections were crucial to (and would have been expected of) the CDC’s investigation and its conclusions in this MMWR Weekly report.
Why would these measures be so crucial to perform? Because if the rinse water had been found to be contaminated with at least one of the microorganisms that infected this outbreak’s affected patients, which both is a possibility and the CDC’s published findings do not rule out, then the deviation identified by the CDC as the outbreak’s apparent cause — namely, that “personnel using automated reprocessing machines in these clusters did not receive adequate device-specific training, and the wrong set-up or connector systems were used” — would lack quality and be inadequate, thereby manifestly not necessarily preventing the outbreak’s future recurrence.
Did the CDC misdiagnosis this outbreak of P. aeruginosa, assigning to it an unrelated and null cause?
Worse, the corrective actions that the CDC issued in this MMWR Weekly (July 9, 1999) to prevent these types of bacterial outbreaks (and their associated morbidity and mortality) — for example, the CDC in this report recommends that “bronchoscope users should obtain and review model-specific reprocessing protocols from both bronchoscope and automated reprocessing system manufacturers” (translated: management should ensure that reprocessing staffers are trained to confirm that the bronchoscope’s channel and ports have been properly connected to the automated reprocessing device) — would not have addressed the outbreak’s true root cause.
That the rinse water might have been contaminated with the outbreak’s microorganisms the CDC’s report does not exclude.
Endoscope drying
What the literature suggests may be one of the single most important preventive measures to thwart such bacterial outbreaks as this one investigated by the CDC — drying the flexible endoscope’s internal channels with 70% alcohol followed by forced air both before storage and between patient procedures — the CDC does not mention in this report of 1999, although ironically the CDC did provide just this same recommendation in a MMWR Weekly published 8 years earlier (dated October 4, 1991 [40(39):675-78] to prevent flexible endoscopes from transmitting such potentially infectious microorganisms as P. aeruginosa.
Which raises a question: Why now did the CDC not repeat the crucial recommendation, which it did provide 8 years earlier in a similar report in MMWR Weekly, in 1991, to dry the bronchoscope, to prevent such types of bacterial outbreaks?
Read Dr. Muscarella blog “Review of an Outbreak of Pseudomonas aeruginosa Following Arthroscopy in Texas, 2009″ by clicking here.
The medical literature
Several reports that discuss waterborne microorganisms re-contaminating flexible endoscopes have been published.1,3,5 Each underscores the importance of drying the endoscope’s internal channels to all but eliminate the risk of the endoscope transmitting opportunistic waterborne diseases to patients,3,7,11 whether the source of the microorganisms is the environment or an index case-patient.
Rinsing all of the endoscope’s channels with 70% alcohol (to facilitate drying before storage), followed by forced air drying, has become recommended by Dr. Muscarella for years.
Read Dr. Muscarella’s peer-reviewed article “Inconsistencies in Endoscope-Reprocessing and Infection-Control Guidelines: The Importance of Endoscope Drying” by clicking here.
Moreover:
- Strulens et al.1 reported that tap water, passed through a filter membrane designed to produce ‘sterile’ water, remained contaminated with P. aeruginosa, re-contaminating the endoscope during rinsing. Transmission of waterborne microorganisms from the endoscope to the patient was eradicated only after the endoscope’s channels were terminally rinsed with 70% alcohol, followed by forced air drying;
- Allen et al.3 reported patient infection and death linked to inadequately dried endoscopes contaminated with P. aeruginosa. This outbreak abruptly stopped only after the endoscope was dried before storage by suctioning 70% alcohol through its channels followed by forced air;
- Alvarado et al.12 reported that rinsing the endoscope’s channels with 70% alcohol, followed by forced air drying, eliminated the contamination of endoscopes with P. aeruginosa (even though the automated reprocessor remained contaminated); and
- Ironically, again, in the CDC report’s in MMWR Weekly of 1991, rinsing the endoscope’s internal channels with 70% (iso-propyl) alcohol, followed by forced air drying, was reported to significantly reduce the risk of infecting patients with P. aeruginosa. (It remains unclear why the CDC did not discuss in 1999 the importance to the prevention of disease transmission of drying the flexible endoscope’s internal channels after reprocessing, as it did in 1991.)
Conclusions
To prevent the transmission of waterborne microorganisms, including P. aeruginosa and atypical mycobacteria, such as MAI, during flexible endoscopy, several practices are emphasized:
- Dry the endoscope both before storage and between patent procedures, no matter whether using a tap or filtered water rinse.1-3,11-18 Drying can be achieved by rinsing the flexible endoscope’s internal channels with 70% alcohol, followed by forced air;
- Vertically hang the endoscope in a clean, dry and well-ventilated cabinet.17,18 Storing the endoscope in a coiled position is contraindicated, as it may prevent drying and allow bacteria to colonize in its internal channels during storage.19 Also, remove the endoscope’s control valves during storage to further facilitate drying;17
- Leak test the endoscope, per manufacturer’s instructions, not only to protect its functional integrity, but also to reduce the risk of cross-infection by detecting tears and punctures, capable of harboring microorganisms,14,20 in the walls of the endoscope’s internal channels; and
- Contact the automated endoscope reprocessor’s manufacturer to ensure its device can connect to, and is validated (through a quality-assurance and design-control program) to reprocess, each of the endoscope’s internal channels.
Article by: Lawrence F Muscarella, PhD, posted 4/10/2013; updated 11/4/2014.
References
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2. Kolmos HJ, Lerche A, Kristoffersen K, Rosdahl VT. 1994. Pseudo-outbreak of Pseudomonas aeruginosa in HIV-infected patients undergoing fiberoptic bronchoscopy. Scand J Infect Dis 26:653– 657.
3. Allen JI, Allen MO, Olson MM, et al. Pseudomonas infection of the biliary system resulting from use of a contaminated endoscope. Gastroenterology 1987;92:759–63.
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11. Gerding DN, Peterson LR, Vennes JA. Cleaning and disinfection of fiberoptic endoscopes: evaluation of glutaraldehyde exposure time and forced-air drying. Gastroenterology 1982 Sep;83(3):613-8.
12. Alvarado C, Stolz SM, Maki DG. Nosocomial infections from contaminated endoscopes: A flawed automated endoscope washer. An investigation using molecular epidemiology. Am J Med 1991;91(suppl 3B):272S–80S.
13. Muscarella LF. Leading a horse to water: are crucial lessons in endoscopy and outbreak investigations being learned? Infect Control Hosp Epidemiol 2002 Jul;23(7):358-60; author reply 360.
14. Agerton T, Valway S, Gore B, Pozsik C, Plikaytis B, Woodley C, Onorato I. 1997. Transmission of a highly drug-resistant strain (strain W1) of Mycobacterium tuberculosis. Community outbreak and nosocomial transmission via a contaminated bronchoscope. JAMA 278:1073–1077.
15. Fraser VJ, Jones M, Murray PR, Medoff G, Zhang Y, Wallace RJ, Jr. 1992. Contamination of flexible fiberoptic bronchoscopes with Mycobacterium chelonae linked to an automated bronchoscope disinfection machine. Am Rev Respir Dis 145:853– 855.
16. Michele TM, Cronin WA, Graham NM, Dwyer DM, Pope DS, Harrington S, Chaisson RE, Bishai WR. 1997. Transmission of Mycobacterium tuberculosis by a fiberoptic bronchoscope: identification by DNA fingerprinting. JAMA 278:1093–1095
17. Muscarella LF. The importance of bronchoscope reprocessing guidelines: Raising the standard of care. Chest 2004;126;1001-1003
18. Muscarella LF. Inconsistencies in endoscope-reprocessing and infection-control guidelines: the importance of endoscope drying. Am J Gastroenterol 2006 Sep;101(9):2147-54.
19. Clinical issues. AORN J May, 1997.
20. Pappas SA, Schaaff DM, DiCostanzo MB, King FW, Jr, Sharp JT. 1983. Contamination of flexible fiberoptic bronchoscopes. Am Rev Respir Dis 127:391–392.