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Viral etiology more common in severe CAP than previously thought
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Viral etiology appears to be more prevalent in cases of severe community-associated pneumonia than previously reported, according to recent findings.
In the prospective study, researchers evaluated a cohort of 49 patients who presented to the ICU of a tertiary referral university hospital with severe community-associated pneumonia (CAP) between 2008 and 2012. All patients required intensive care treatment for more than 48 hours and started on mechanical ventilation within 48 hours of admission to the ICU. The study population consisted of 21 men and 28 women, with a median age of 54 years.
The researchers collected demographic and clinical data on the patients and conducted a microbiological evaluation of at least two blood samples within 24 hours of ICU admission. They also collected tracheobronchial aspirates, urine samples and pleural fluid if pleural drainage was required. These samples were tested for Streptococcus pneumoniae and Legionella pneumophila antigens, Mycoplasma pneumoniae and Chlamydia pneumoniae.
Nasopharyngeal swabs, bronchial aspirates and bronchoalveolar lavage were collected and tested via multiplex, real-time PCR for adenovirus; influenza A and B viruses; parainfluenza virus types 1-4; rhinovirus; respiratory syncytial viruses A and B; bocavirus; coronaviruses 229E, NL63 and OC43; metapneumovirus; and enteroviruses.
The investigators were able to identify the disease etiology in 45 of the 49 patients with severe CAP (92%). They identified 21 pure bacterial infections (43%), five infections in which viruses were identified as the only cause (10%) and 19 infections of mixed bacterial-viral etiology (39%), which equaled viral pathogenesis of severe CAP in 24 cases (49%). Of 26 viruses, 21 (81%) were identified in bronchial samples and five (19%) were detected in nasopharyngeal swabs. The most common viruses identified were rhinovirus (15 cases, 58%) and adenovirus (four cases, 15%). The highest C-reactive protein levels were seen in bacterial-viral etiology cases (median, 356; P=.05), whereas patients with likely viral etiology had the lowest peak procalcitonin levels (median, 1.7). Comparable clinical characteristics were seen among the pure bacterial and mixed bacterial-viral cases. Patients in the bacterial group had the longest lengths of stay at the hospital (17 vs. 14 days, P=.02).
“A viral etiology is more common in [severe CAP] than has been reported thus far,” the researchers wrote. “The recovery of viruses in patients with [severe CAP] is influenced by the availability of modern multiple-PCR techniques and the ability to use invasive methods to obtain lower respiratory specimens. The presence of viral etiology does not, however, appear to affect the outcomes of [severe CAP] patients.”
Disclosure: The researchers report no relevant financial disclosures.
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