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Editorial |

Going Viral: Importance of Viral Pathogens in Nonventilated Hospital-Acquired Pneumonia FREE TO VIEW

Andrew F. Shorr, MD, MPH, FCCP; Marya D. Zilberberg, MD, MPH, FCCP
Author and Funding Information

FINANCIAL/NONFINANCIAL DISCLOSURES: The authors have reported to CHEST the following: A. F. S. has served as a consultant to, received research support from, or been a speaker for: Abbott, Actavis, Alios, Astellas, AstraZeneca, Bayer, BMS, Cardeas, Medicines Company, Merck, Pfizer, Roche, Tetraphase, Theravance, and Wockhardt Pharma. M. D. Z. has served as a consultant to or received research funding from Astellas, Medicines Company, Merck, Pfizer, Tetraphase, and Theravance.

aSection of Pulmonary and Critical Care Medicine, Medstar Washington Hospital Center, Washington, DC

bEviMed Research Group, LLC, Goshen, MA

CORRESPONDENCE TO: Andrew F. Shorr, MD, MPH, FCCP, 110 Irving St NW, Washington, DC 20010


Copyright 2016, American College of Chest Physicians. All Rights Reserved.


Chest. 2016;150(5):991-992. doi:10.1016/j.chest.2016.05.028
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Published online

Over the past decade, substantial resources have been focused on ventilator-associated pneumonia (VAP)., Research designed to enhance our appreciation of its pathophysiology has led to a multitude of preventive options., Furthermore, the morbidity penalty associated with VAP underscores the importance of efforts to eliminate VAP as an ICU-related complication. Most important, studies highlighting the importance of initially appropriate antimicrobial therapy have shown means through which we can reduce mortality related to VAP.,

FOR RELATED ARTICLE SEE PAGE 1008

VAP, however, is just 1 type of nosocomial pneumonia (NP). Hospitalized patients who are not ventilated are also at risk for pneumonia, and the pool of such subjects outside the ICU is substantial. Whether correctly or not, most guidelines for NP presume that hospital-acquired pneumonia affecting the nonventilated patient (NVHAP) shares many of the attributes and characteristics of VAP. Given the potential extent of the problem, it is critical to begin to understand the epidemiology, microbiology, and outcomes specific to hospital-acquired pneumonia that arises in the spontaneously breathing patient.

In this issue of CHEST, Micek and colleagues help fill this void in patients who develop NVHAP. In a retrospective, single-center study, they report several important observations. First, NVHAP clearly results in attributable mortality. This finding is key, given that the mortality penalty associated with VAP is rather small. In other words, most patients die with VAP, not of it. In contrast, NVHAP appears to contribute substantially to the risk of death. All the limitations inherent in a small, retrospective, single-center study notwithstanding, the relationship between NHVAP and excess mortality is concerning. Similarly, excess hospital length of stay resulting from a case of NHVAP appears longer than the added length of stay related to VAP. These are compelling arguments for expanding quality and safety efforts related to NP beyond the ICU, because a narrow focus on VAP only neglects a companion disease that may lead to even more avoidable deaths and costs than one that already requires public reporting. With the findings from Micek et al in hand, we need to demand more research into the early identification of those suffering from NVHAP and potential preventive measures.

Second, Micek et al report striking results regarding the microbiology of NVHAP. Guidelines urge physicians in the United States to treat patients with suspected NVHAP with some combination of broad-spectrum antimicrobials. The major concerns are for such antibiotic-resistant organisms as Pseudomonas aeruginosa, extended spectrum beta-lactamase producing Enterobacteriaceae, and methicillin-resistant Staphylococcus aureus. Although the authors demonstrate that such pathogens can certainly be recovered in NHVAP, infections were equally likely to be viral as bacterial.

In community-acquired pneumonia, the importance of viruses was recently confirmed by Jain and coworkers in a large multicenter surveillance study in which viruses were isolated twice as frequently as bacteria. The importance of viral pathogens in NP, however, is a relatively recent discovery. Though recognized as important causes of NP among the immunocompromised, few patients in the report by Micek et al fell into this category through high-dose chemotherapy, a stem cell transplant, or a solid organ transplant. Admittedly, as a retrospective study relying on usual clinical practices, the current report by Micek et al reflects a search for potential viral pathogens only when clinically suspected, rather than according to a systematic protocol for viral diagnostic tests. This suggests that the reported prevalence of viral infections represents an underestimate rather than an overestimate. Thus, one has to wonder how many of those patients classified as culture negative might have actually had an infection caused by a virus.

Several reports have implicated virus as an important cause of other forms of NP. Hong et al documented viruses as causative in VAP in 22.5% of cases, whereas Choi and colleagues estimated that nearly one-third of cases of health-care–associated pneumonia were related to viral infection. Taken as whole, these studies from various forms of NP suggest that we must search for viral pathogens in hospitalized patients with new-onset pneumonia rather than presume that viruses are only an issue in subjects with community-acquired pneumonia.

Additionally, the significance of viruses as a cause of NP has several clear clinical implications. Because antibiotics will not help those suffering from a viral infection, the search for (and potential identification of) a viral cause will facilitate antibiotic de-escalation and stewardship. In many situations, culture negative NVHAP patients receive a 7- to 10-day course of antibiotics. By limiting exposure to such agents because a virus has been identified, we can help prevent the emergence of further resistance as well as individual consequences of unnecessary antibiotic exposure, such as gut dysbiosis and Clostridium difficile infection. Finally, as rapid diagnostic tools are being developed for pneumonia, the manufacturers of these tests need to ensure that they include means not only for identifying bacteria, but also for determining if a viral pathogen is present.

In summary, the results presented by Micek et al not only provide important information about the outcomes related to NVHAP, they also point to potential ways for practicing clinicians to improve the care of their patients.

References

American Thoracic SocietyInfectious Diseases Society of America Guidelines for the management of adults with hospital-acquired, ventilator-associated, and healthcare-associated pneumonia. Am J Respir Crit Care Med. 2005;171:388-416 [PubMed]journal. [CrossRef] [PubMed]
 
Zilberberg M.D. .Shorr A.F. . Ventilator-associated pneumonia as a model for approaching cost-effectiveness and infection prevention in the ICU. Curr Opin Infect Dis. 2011;24:385-389 [PubMed]journal. [CrossRef] [PubMed]
 
Kollef M.H. . Prevention of nosocomial pneumonia in the intensive care unit: beyond the use of bundles. Surg Infect (Larchmt). 2011;12:211-220 [PubMed]journal. [CrossRef] [PubMed]
 
Muscedere J.G. .Shorr A.F. .Jiang X. .Day A. .Heyland D.K. . Canadian Critical Care Trials Group The adequacy of timely empiric antibiotic therapy for ventilator-associated pneumonia: an important determinant of outcome. J Crit Care. 2012;27:322.e7-322.e14 [PubMed]journal. [CrossRef]
 
Iregui M. .Ward S. .Sherman G. .Fraser V.J. .Kollef M.H. . Clinical importance of delays in the initiation of appropriate antibiotic treatment for ventilator-associated pneumonia. Chest. 2002;122:262-268 [PubMed]journal. [CrossRef] [PubMed]
 
Micek S.T. .Chew B. .Hampton N. .Kollef M.H. . A case-control study assessing the impact of nonventilated hospital-acquired pneumonia on patient outcomes. Chest. 2016;150:1008-1014 [PubMed]journal. [CrossRef]
 
Jain S. .Self W.H. .Wunderink R.G. .et al Community-acquired pneumonia requiring hospitalization among U.S. adults. N Engl J Med. 2015;373:415-427 [PubMed]journal. [CrossRef] [PubMed]
 
Hong H.L. .Hong S.B. .Ko G.B. .et al Viral infection is not uncommon in adult patients with severe hospital-acquired pneumonia. PLoS One. 2014 21;9:e95865- [PubMed]journal. [CrossRef] [PubMed]
 
Choi S.H. .Hong S.B. .Ko G.B. .et al Viral infection in patients with severe pneumonia requiring intensive care unit admission. Am J Respir Crit Care Med. 2012;186:325-332 [PubMed]journal. [CrossRef] [PubMed]
 

Figures

Tables

References

American Thoracic SocietyInfectious Diseases Society of America Guidelines for the management of adults with hospital-acquired, ventilator-associated, and healthcare-associated pneumonia. Am J Respir Crit Care Med. 2005;171:388-416 [PubMed]journal. [CrossRef] [PubMed]
 
Zilberberg M.D. .Shorr A.F. . Ventilator-associated pneumonia as a model for approaching cost-effectiveness and infection prevention in the ICU. Curr Opin Infect Dis. 2011;24:385-389 [PubMed]journal. [CrossRef] [PubMed]
 
Kollef M.H. . Prevention of nosocomial pneumonia in the intensive care unit: beyond the use of bundles. Surg Infect (Larchmt). 2011;12:211-220 [PubMed]journal. [CrossRef] [PubMed]
 
Muscedere J.G. .Shorr A.F. .Jiang X. .Day A. .Heyland D.K. . Canadian Critical Care Trials Group The adequacy of timely empiric antibiotic therapy for ventilator-associated pneumonia: an important determinant of outcome. J Crit Care. 2012;27:322.e7-322.e14 [PubMed]journal. [CrossRef]
 
Iregui M. .Ward S. .Sherman G. .Fraser V.J. .Kollef M.H. . Clinical importance of delays in the initiation of appropriate antibiotic treatment for ventilator-associated pneumonia. Chest. 2002;122:262-268 [PubMed]journal. [CrossRef] [PubMed]
 
Micek S.T. .Chew B. .Hampton N. .Kollef M.H. . A case-control study assessing the impact of nonventilated hospital-acquired pneumonia on patient outcomes. Chest. 2016;150:1008-1014 [PubMed]journal. [CrossRef]
 
Jain S. .Self W.H. .Wunderink R.G. .et al Community-acquired pneumonia requiring hospitalization among U.S. adults. N Engl J Med. 2015;373:415-427 [PubMed]journal. [CrossRef] [PubMed]
 
Hong H.L. .Hong S.B. .Ko G.B. .et al Viral infection is not uncommon in adult patients with severe hospital-acquired pneumonia. PLoS One. 2014 21;9:e95865- [PubMed]journal. [CrossRef] [PubMed]
 
Choi S.H. .Hong S.B. .Ko G.B. .et al Viral infection in patients with severe pneumonia requiring intensive care unit admission. Am J Respir Crit Care Med. 2012;186:325-332 [PubMed]journal. [CrossRef] [PubMed]
 
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