Nosocomial pneumonia, categorized as hospital-acquired pneumonia (HAP) and the separately defined ventilator-associated pneumonia (VAP), add enormous cost to healthcare each year and cause much suffering for our patients.1,2 A great deal of research has focused on why patients get pneumonia in hospitals. Based on the results of those studies, policy and procedure changes have been specifically adopted to improve prevention, identification and treatment at the national, state and local levels.1 Those efforts show varying levels of success with major analyses revealing that the rates of incidence of HAP and VAP have remained stable or are decreasing but have not been eliminated.2,3,4
In spite of advances and the extraordinary effort that hospitals expend to prevent, diagnose and treat hospital-acquired infections, the incidence is still high enough to demand more attention.3 The key to preventing respiratory infections including pneumonia obviously requires understanding etiologic factors and identifying those which are susceptible to mitigation efforts. Microaspiration of colonized bacteria of the oropharynx leads to most lung infections overall. Nearly half of all healthy people, and even more ill patients aspirate routinely during sleep. Most of the time, this is a benign process overcome by host defenses but in some cases, lower respiratory tract infections such as pneumonia may result.3,4,5 Whether measures preventing or reducing the effects of microaspiration are possible or useful is the subject of ongoing debate. Instrumenting the airway certainly exacerbates this problem.
Critically ill hospitalized patients, in addition to infection from their own microbial flora, become colonized at an alarming rate of 75 percent within 48 hours of admission from exposure to the hospital environment.5 Poor hand hygiene, accidental cross-contamination and airborne vectors are the most obvious studied and addressed factors. Other, less common or well-known pathways to infection now deserve the focus of further study and intervention.
Notably, the sources of outbreaks of infection for ventilated patients are most often the devices and instruments that are used to help diagnose and heal, especially instruments used in respiratory care such as bronchoscopes and ventilator equipment.1, 5, 6 Contaminated nebulizers, water reservoirs and bronchoscopes seem to be the most commonly implicated. In fact, contaminated bronchoscopes have led to deadly outbreaks of bacterial pneumonia and tuberculosis despite reported adherence to proper cleaning and disinfection of these scopes.5, 6 For myriad reasons, these bronchoscopes, like endoscopes, present unique difficulties in cleaning. They cannot be sterilized with heat or the same harsh chemicals as other equipment because the delicate components of the instrument would be ruined. Even though only disinfection is required, there are still hard to reach parts of the scope that are easily missed on a microscopic level and thus harbor dangerous pathogens that can and have been passed on to the next patient. 1,5,6
Future improvement in decreasing rates of pneumonia in hospitalized patients lies in addressing these issues as well as continued vigilance with universal and infectious precautions. Consideration should be given to using disposable, single-use equipment where available. Ventilator and respiratory devices such as laryngoscopes, bronchoscopes and tubing which are notoriously hard to clean and likely to be colonized despite best practices, would be worthy of evaluation for replacement with disposable units where technically and economically feasible.1,7
1. Kalil AC, Metersky ML, Klompas M, et al., “Management of Adults With Hospital-acquired and Ventilator-associated Pneumonia: 2016 Clinical Practice Guidelines by the Infectious Diseases Society of America and the American Thoracic Society.” Clinical Infectious Diseases: An Official Publication of the Infectious Diseases Society of America. 2016;63(5):e61-e111. doi:10.1093/cid/ciw353. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4981759/
2. Mark L. Metersky, Yun Wang, Michael Klompas, Sheila Eckenrode, Anila Bakullari, Noel Eldridge. “Trend in Ventilator-Associated Pneumonia Rates Between 2005 and 2013.” JAMA. 2016;316(22):2427–2429. doi:10.1001/jama.2016.16226. https://jamanetwork.com/journals/jama/fullarticle/2583369
3. Karen K. Giuliano, Dian Baker, Barbara Quinn. “The Epidemiology of Nonventilator Hospital-acquired Pneumonia in the United States.” American Journal of Infection Control. Available online 16 October 2017. http://dx.doi.org/10.1016/j.ajic.2017.09.005
4. Khan, Raymond et al. “The impact of implementing multifaceted interventions on the prevention of ventilator-associated pneumonia,” American Journal of Infection Control, Volume 44 , Issue 3 , 320–326
5. Nasia Safdar, Christopher J Crnich, Dennis G Maki. “The Pathogenesis of Ventilator-Associated Pneumonia: Its Relevance to Developing Effective Strategies for Prevention,” Respiratory Care, Jun 2005, 50 (6) 725–741 http://rc.rcjournal.com/content/respcare/50/6/725.full.pdf
6. Srinivasan A, Wolfenden LL, Song X, Mackie K, Hartsell TL, Jones HD, et al. “An outbreak of Pseudomonas aeruginosa infections associated with flexible bronchoscopes.” N Engl J Med 2003; 348(3):221–227.
7. Association of Anaesthetists of Great Britain and Ireland. “Infection Control in Anaesthesia.” Anaesthesia, 2008, 63: 1027–1036. http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2044.2008.05657.x/full