Atypical aetiology in patients hospitalised with community-acquired pneumonia is associated with age, gender and season; a data-analysis on four Dutch cohorts.
Microorganisms causing community-acquired pneumonia (CAP) can be categorised into viral, typical and atypical (Legionella species, Coxiella burnetii, Mycoplasma pneumoniae, and Chlamydia species). Extensive microbiological testing to identify the causative microorganism is not standardly recommended, and empiric treatment does not always cover atypical pathogens. In order to optimize epidemiologic knowledge of CAP and to improve empiric antibiotic choice, we investigated whether atypical microorganisms are associated with a particular season or with the patient characteristics age, gender, or chronic obstructive pulmonary disease (COPD).



A data-analysis was performed on databases from four prospective studies, which all included adult patients hospitalised with CAP in the Netherlands (N = 980). All studies performed extensive microbiological testing.



A main causative agent was identified in 565/980 (57.7 %) patients. Of these, 117 (20.7 %) were atypical microorganisms. This percentage was 40.4 % (57/141) during the non-respiratory season (week 20 to week 39, early May to early October), and 67.2 % (41/61) for patients under the age of 60 during this season. Factors that were associated with atypical causative agents were: CAP acquired in the non-respiratory season (odds ratio (OR) 4.3, 95 % CI 2.68-6.84), age <60 year (OR 2.9, 95 % CI 1.83-4.66), male gender (OR 1.7, 95 % CI 1.06-2.71) and absence of COPD (OR 0.2, 95 % CI 0.12-0.52).



Atypical causative agents in CAP are associated with respectively non-respiratory season, age <60 years, male gender and absence of COPD. Therefore, to maximise its yield, extensive microbiological testing should be considered in patients <60 years old who are admitted with CAP from early May to early October.



NCT00471640 , NCT00170196 (numbers of original studies).
Department of Internal Medicine, St Antonius Hospital, Nieuwegein, The Netherlands.|Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, The Netherlands.
Vivian M
VM
Raeven
Department of Internal Medicine, St Antonius Hospital, Nieuwegein, The Netherlands. s.spoorenberg@antoniusziekenhuis.nl.
Simone M C
SM
Spoorenberg
Department of Pulmonary Medicine, Medical Centre Alkmaar, Alkmaar, The Netherlands.
Wim G
WG
Boersma
Department of Clinical Pharmacy, St. Antonius Hospital, Nieuwegein, The Netherlands.|Division of Pharmacoepidemiology and Clinical Pharmacology, Faculty of Science, Utrecht University, Utrecht, The Netherlands.
Ewoudt M W
EM
van de Garde
Department of Clinical Epidemiology, Leiden University Medical Centre, Leiden, The Netherlands.
Suzanne C
SC
Cannegieter
Department of Medical Microbiology and Immunology, St. Antonius Hospital, Nieuwegein, The Netherlands.
G P Paul
GP
Voorn
Department of Internal Medicine, St Antonius Hospital, Nieuwegein, The Netherlands.
Willem Jan W
WJ
Bos
Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, The Netherlands.|Centre of Infectious Diseases, Leiden University Medical Centre, Leiden, The Netherlands.
Jim E
JE
van Steenbergen
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D002689:Chlamydia / Q000302:isolation & purification; D002690:Chlamydia Infections / Q000453:epidemiology / Q000382:microbiology; D017714:Community-Acquired Infections / Q000453:epidemiology / Q000382:microbiology; D016997:Coxiella burnetii / Q000302:isolation & purification; D005260:Female; D005334:Fever / Q000453:epidemiology / Q000382:microbiology; D006760:Hospitalization; D006801:Humans; D007875:Legionella / Q000302:isolation & purification; D007876:Legionellosis / Q000453:epidemiology / Q000382:microbiology; D008297:Male; D008875:Middle Aged; D009177:Mycoplasma pneumoniae / Q000302:isolation & purification; D009426:Netherlands / Q000453:epidemiology; D016017:Odds Ratio; D018410:Pneumonia, Bacterial / Q000453:epidemiology / Q000382:microbiology*; D011019:Pneumonia, Mycoplasma / Q000453:epidemiology; D011446:Prospective Studies; D012621:Seasons; D012737:Sex Factors
D000900:Anti-Bacterial Agents
Aetiology; Atypical pathogens; Community-acquired pneumonia; Demography; Pneumonia