Hospital-Acquired Pneumonia/Ventilator-Associated Pneumonia after Guidelines

Ignacio Martin-Loeches, MD

Antoni Torres, MD, PhD, FERS, FCCP, ATSF

The last Infectious Diseases Society of America/American Thoracic Society and European guidelines for the management of hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) were published in 2016 and 2017, respectively. Since then, vast information about several new aspects regarding HAP and VAP has come to light. For this primary reason, there is a need to publish an updated issue in Seminars of Respiratory and Critical Care Medicine (SRRCCM).

The article (J. F. Timsit) centers on the new classification of nosocomial pneumonia. This focus comes in response to evidence supporting that individuals with HAP requiring mechanical ventilation comprise a highly important patient group with a particular bad prognosis.

New concepts regarding HAP and VAP physiopathology include dysbiosis of the gastrointestinal tract and changes in microbiome (A. Roquilly). These understandings may influence strategies related to prevention and treatment.

A rapid and accurate microbial diagnosis is crucial in both HAP and VAP, so clinicians may initiate early, adequate antibiotic treatment. HAP and VAP constitute infectious diseases. As such, the use of rapid molecular techniques could improve antibiotic strategies.

In most HAP and VAP cases, initial antibiotic treatment is empirical. However, in a time when multiresistance has grown in prevalence, clinical risk factors related to suspected cases of multidrug-resistant (MDR)/extensively drug-resistant (XDR) microorganisms play a pivotal role in the starting approach. Algorithms included in the 2016 and 2017 guidelines are reviewed by Michael Niederman.

Viruses could cause HAP/VAP, either alone or in conjunction with bacteria. Herpes simplex and cytomegalovirus represent the most frequently isolated viruses in such cases. There is current debate about treating these viruses or not. Viral HAP and VAP are reviewed by Charles Edouard Louyt and Jean Chastre.

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most frequent bacterial causes of HAP and VAP, requiring specific antibiotic treatments. Colonization in nasal and respiratory secretions prior to HAP or VAP is an important predictor for early and adequate antibiotic treatment. Polymerase chain reaction (PCR) molecular techniques for early MRSA detection are cost-effective in this type of HAP/VAP infections. All of these issues are reviewed by Rich Wunderink and colleagues.

Pseudomonas aeruginosa is another microorganism responsible for HAP and VAP. There are several well-recognized clinical risk factors that can help in initially suspected cases. MDR/XDR Pseudomonas poses a major problem. Some new anti-gram-negative bacilli (GNB) antibiotics are effective in treating MDR/XDR Pseudomonas. The topic of HAP/VAP caused by Pseudomonas is reviewed by Joseph Lynch and George Zhanel.

Aspergillus spp. is a forgotten microbial enemy, especially in cases of VAP. This microorganism may cause between 10 and 15% of all VAP cases. Early and adequate antifungal treatment is essential. Correct diagnostic approaches include measuring galactomannan in bronchoalveolar lavage, cultures, and PCR. Dr. Andrew Conway-Morris addresses this difficult problem.

Within the past 5 years, several new antibiotics, especially targeting GNB MDR/XDR, have been developed and become available. Each one of these breakthrough antibiotics covers a particular mechanism of resistance. Dr. Matteo Bassetti summarizes indications for these new antibiotics, as well as their mechanisms of action and spectrum of activity.

Nebulized antibiotics are used in patients with VAP to achieve extremely high concentrations of bronchial antibiotics (e.g., aminoglycosides) with minimal concentrations in plasma. The two most important randomized clinical trials in VAP were negative. Led by Jean-Jacques Rouby, the multidisciplinary group on nebulized antibiotics in intensive care reviews the pros and cons of co-adjuvant administration of nebulized antibiotics in cases of VAP.

Guidelines for HAP and VAP recommend the use of pharmacokinetic (PK)/pharmacodynamic (PD) parameters to guide initial and maintained antibiotic treatments. However, in most HAP and VAP cases within the clinical setting, implementation of PK/PD-guided practices does not occur. Led by Dr. Dave Nicolau, the Hardford group reviews all of these PK/PD concepts and their potential clinical applications.

Finally, Dr. Ceccato and Dr. Torres define early clinical and microbiological failure. In the latter case, early follow-up of microbial cultures can prove useful in predicting outcomes. Early clinical and microbiological no-response concepts should be integrated in randomized controlled trials comparing antibiotics.

In summary, this issue of SRRCCM on HAP/VAP aims to include the most significant novelties gained within the field after the publications of the 2016 and 2017 guidelines.

Publication History

Article published online:
21 January 2022