Description and characterization of pneumococcal community acquired pneumonia (CAP) among radiologically confirmed CAP in outpatients

Abstract

Streptococcus pneumoniae (SP) remains an important cause of community acquired pneumonia (CAP). We aimed to describe the prevalence and characteristics of outpatients with radiologically confirmed pneumococcal CAP. Between November 2017 and December 2019, a French network of general practitioners enrolled CAP-suspected adults, with ≥1 clinical signs of infection and ≥1 signs of pulmonary localization in an observational study. Pneumococcal CAP was defined by the combination of a chest X-ray (CXR) compatible with CAP and SP detection by any of four microbiological tests (blood culture, sputum culture, pneumococcal urinary antigen test [BinaxNow®] and serotype-specific multiplex urinary antigen detection test [Pfizer Inc®]. To identify other pathogens, next to cultures, nasopharyngeal multiplex PCR was performed. Three hundred and forty-eight patients were included, of whom 144 had a positive CXR, 135/144 (93.8%) had not received antibiotics prior to inclusion, 21/144 (14.6%) had ≥1 positive microbiological test for SP, and 66/144 (45.8%) were negative for all four microbiological tests and were considered as non-pneumococcal CAP. Pneumococcal serotypes were identified for 12 patients. This study assessing the prevalence of SP among CAP outpatients using comprehensive microbiologic testing shows that SP is still the most frequently identified microorganism.

Fig. 1. Flow chart of patients enrolled in the PneumoCAP study.

D0 Day 0 (date of inclusion), CAP community acquired pneumonia, CXR+ positive chest X-ray, CXR- negative chest X-ray.

Fig. 2. Streptococcus pneumoniae identification according to microbiological tests in the 21 patients with pneumococcal CAP.

Among the 144 patients CAP CXR+, microbiological tests were performed as follows: sputum sample testing for 87 patients, UAD (serotype-specific multiplex urinary antigen detection) for 127 patients, blood culture for 112 patients, pneumococcal urinary antigen test for 127 patients. UAD UAD serotype-specific multiplex urinary antigen detection test.

Fig. 3. Pathogen detection among 144 patients with positive chest X-ray.

Viruses only (N = 27), Human Bocavirus (N = 1), Adenovirus (N = 2), Enterovirus and Rhinovirus (N = 9), Metapneumovirus (N = 5). Respiratory syncytial virus (RSV) (N = 1), Parainfluenza virus (1,2,3,4) (N = 1), Influenza virus B (N = 1), Influenza virus A (N = 5), Influenza virus A + Enterovirus + Rhinovirus (N = 1), Influenza virus A + Parainfluenza virus (1,2,3,4) (N = 1), Bacteria and viruses’ co-detection, other than Streptococcus pneumoniae (N = 6), Enterovirus + Rhinovirus + Neisseria + Escherichia coli + undetermined bacteria (N = 1), Enterovirus + Rhinovirus + Staphylococcus aureus (N = 1), Enterovirus + Rhinovirus + Mycoplasma pneumoniae (N = 1), Metapneumovirus + Staphylococcus capitis (N = 1), Parainfluenza virus + Enterovirus + Rhinovirus + Streptococcus alpha-hemolytic + undetermined bacteria (N = 1), Influenza virus A + undetermined bacteria (N = 1), Streptococcus pneumoniae and viruses’ co-detection (N = 8), Streptococcus pneumoniae + Enterovirus + Rhinovirus (N = 3), Streptococcus pneumoniae + Respiratory syncytial virus (N = 1), Streptococcus pneumoniae + Influenza virus B (N = 1), Streptococcus pneumoniae + Influenza virus A (N = 3), Streptococcus pneumoniae and bacteria co-detection (N = 13), Streptococcus pneumoniae (N = 10). Streptococcus pneumoniae + Haemophilius influenzae (N = 1), Streptococcus pneumoniae + Neisseria + undetermined bacteria (N = 2), Bacteria only, other than Streptococcus pneumoniae (N = 19), Undetermined bacteria (N = 1), Streptococcus beta-hemolytic (N = 1), Streptococcus alpha-hemolytic (N = 2), Streptococcus alpha-hemolytic + undetermined bacteria (N = 1), Streptococcus alpha-hemolytic + Escherichia coli (N = 1), Streptococcus alpha-hemolytic + Streptococcus beta-hemolytic (N = 2), Staphylococcus aureus (N = 4), Pseudomonas aeruginosa + Escherichia coli (N = 1), Haemophilius influenzae (N = 2), Chlamydiophila (N = 1), Mycoplasma pneumoniae (N = 3).

Fig. 4. PneumoCAP study procedures.

D0 Day 0 (date of inclusion), CAP community acquired pneumonia, eCRF online case report form.