Microbial aetiology of community-acquired pneumonia and its relation to severity

Abstract

BackgroundThe distribution of the microbial aetiology and mortality of community-acquired pneumonia (CAP) was investigated in relation to the clinical setting and severity scores (pneumonia severity index (PSI) and confusion, blood urea nitrogen, respiratory rate, blood pressure, age (CURB-65)). Methods 3523 patients with CAP were included (15% outpatients, 85% inpatients). The distribution of the microbial aetiology in relation to the clinical setting and severity scores (PSI, CURB-65) and the relative mortality of different aetiologies across the severity scores were analysed. Results The aetiology was established in 1463 patients (42%), of whom 257 died (7%). The ranking of aetiologies varied according to site of care, with increasing frequency of Streptococcus pneumoniae and mixed aetiologies and decreasing frequency of atypical pathogens in hospitalised patients and those in ICUs. The distribution of aetiologies according to severity scores showed corresponding patterns; however, the severity scores were more sensitive to Gram-negative enteric bacilli (GNEB) and Pseudomonas aeruginosa and less sensitive in identifying mixed aetiologies as moderateand high-risk conditions. Mortality rates according to aetiology and severity scoring showed increasing mortality rates for all pathogens except atypical pathogens. S pneumoniae had the highest number of deaths while GNEB, P aeruginosa, Staphylococcus aureus and mixed aetiologies had the highest mortality rates. Legionella pneumophila was similarly distributed according to site of care and prognostic scores. Conclusions CAP due to atypical bacterial pathogens is recognised both clinically and by severity scoring as a low-risk condition. Severity scores are more sensitive in identifying patients with GNEB and P aeruginosa as moderate-and high-risk aetiologies whereas mixed aetiologies may be underestimated.

Non-invasive ventilation in the treatment of severe polymicrobial community-acquired pneumonia

“…13,14 S. pneumoniae was the most frequent co-pathogen in polymicrobial infections as previously reported. 15,16 Our case series report the most frequent causative organisms in hospitalized patients: 17 it is not clear if the severity of the clinical picture is due to polymicrobial etiology or to causative organism in itself (e.g., L. pneumophila). 18 Undoubtedly bacterial respiratory infection is often preceded by a viral infection which favors the secondary bacterial infection caused by a pathogen colonizing the respiratory mucosa.…”

“…13 For clinicians, it is very important: combined-empirical antimicrobial therapy may reduce mortality: 18 International Guidelines have incorporated the idea that CAP could be due to polymicrobial agents in all patients. 10,[15][16][17] Rapid detection of Influenza may allow physician to use neuraminidase inhibitors effectively within 36 to 48 h from symptoms onset as well as rapid detection of L. pneumophila or S. pneumoniae via urinary test. 18 The role of NIV is still under debate for patients with severe respiratory failure due to community acquired pneumonia because of lack of controlled clinical trials and its efficacy is less evident in decreasing the needs of intubation than in other diseases such as chronic obstructive pulmonary disease or cardiogenic pulmonary edema.…”

Fulminant Community-Acquired Hemorrhagic Pneumonia due to Pseudomonas aeruginosa in a Patient With Anorexia Nervosa

“…Firstly, anorexia nervosa can be a risk factor for CAP due to P. aeruginosa. P. aeruginosa is a rare pathogen that causes CAP [1][2][3][4]. Several risk factors have been reported for CAP due to P. aeruginosa such as probable aspiration, previous hospital admission, previous use of antibiotics, pulmonary comorbidity, male sex and pneumonia severity index risk class IV to V [2,5].…”

“…Pseudomonas aeruginosa is a rare pathogen of communityacquired pneumonia (CAP) [1][2][3][4]. CAP due to this pathogen is associated with higher cases of inappropriate initial therapy and mortality [2].…”

Time to Blood Culture Positivity as a Predictor of Clinical Outcomes and Severity in Adults with Bacteremic Pneumococcal Pneumonia

“…Streptococcus pneumoniae remains the most frequent cause of community-acquired pneumonia (CAP) [1,2]. Bacteremia is documented in 25% of cases [3] and their mortality is 15% to 26% greater than in non-bacteremic patients [4].…”