Introduction
Viral
community-acquired
pneumonia (CAP) is the leading source of significant morbidity and
mortality worldwide [1]. The availability of multiplex
molecular-diagnostic techniques has revolutionized the interpretation of
the role of respiratory viruses in pneumonia in adults [2]. The
prevalence of viral CAP in hospitalized patients varies from 6% to 58%
according to different populations and the proportion of CAP caused by
respiratory virus climbs [3]. Moreover, the emergence of new
viruses, such as severe acute respiratory syndrome coronavirus 2
(SARS-CoV-2)
and avian influenza A, has caused serious viral pneumonia with high
mortality rates [4, 5], which attaches great importance to the
research of viral CAP.
Little work has been done before and it is only during the pandemic of
2009 that bacterial superinfection is highlighted as a complication of
viral CAP [6]. Bacterial pneumonia complicated between 25-50% of
severe patients with influenza and will be the most important pathogenic
cause of patient outcome [7-9], with the mortality climbing to
50-60%, even when appropriate antibiotics have been used [10].
Furthermore, dual Aspergillus and influenza infection is emerging
and 67% mortality is linked to Aspergillosis highlights the
concern for viral-fungal superinfection especially in patients with
severe viral infection [11-13]. However, most conclusions addressing
bacterial/fungal complications are from patients with influenza
pneumonia admitted to ICU[14], or have included patients without
pneumonia[15] or have involved only pediatric patients[16], or
from immunocompromised patients with CAP[17], all of which may lead
to significant misapprehension about the impact of superinfection on the
overall population of patients with viral CAP. A recent multicenter
study demonstrated that complications were common in patients with
non-influenza viral pneumonia and the impact of non-influenza viruses on
clinical outcomes was comparable with that of influenza virus in
immunocompetent adult patients [18]. It is unclear whether the risk
of superinfection of non-influenza pneumonia is similar to that of
influenza pneumonia, especially for SARS-CoV-2. There is also a dearth
of clinical data to figure out the potential impact of superinfection on
the outcome of patients with viral CAP [6].
Early implementation of treatments to limit the possibility of
superinfection may reduce the mortality of patients with influenza and
delaying antimicrobial medication could be associated with higher
mortality [19]. Conversely, previous studies have also shown that
in-hospital all-cause mortality is significantly higher among patients
who continue to receive antibiotics after viral respiratory infection
diagnosis without bacterial infection [20], and overuse of
antibiotics is associated with the emergence of antibiotic-resistant
pathogens [20], makes patients with influenza prone toAspergillus infection [13]. Therefore, deciding who should be
treated for bacterial/fungal superinfections has been the focus of
considerable effort for hospitalized individuals with viral pneumonia
[21]. Although a variety of factors such as mechanical ventilation,
ICU admission, cardiovascular disease, older age, lymphocyte count have
identified as the risk factors for the development of superinfection in
patients with influenza [10, 22], there are few studies for patients
with viral CAP, not merely with influenza, at an early stage.
In this study, we conducted a 2-year observational study to investigate
the incidence and impact of bacterial/fungal complications in patients
hospitalized with viral pneumonia and to identify predictors for the
development of superinfection at an early stage.