Guidelines for severe community-acquired pneumonia in the western world

Recently, several guidelines (ATS 1993/IDSA 1998; ERS 1998; SWAB 1998) have been issued for the initial therapy of patients with community-acquired pneumonia. In patients who fulfil the criteria for severe community-acquired pneumonia (SCAP), it was advised to start with a macrolide (active against Legionella spp. and Mycoplasma pneumoniae) in combination with an agent active against both pneumococci and Pseudomonas aeruginosa by the ATS/IDSA guidelines, while the ERS suggested starting with a second or third generation cephalosporin, in combination with either a macrolide or second generation quinolon plus or minus rifampicin. In the SWAB guidelines, no recommendations for SCAP were made.

Sixty-two cases admitted to the intensive care units of a tertiary-care university hospital with SCAP between 1992 and 1996 were studied retrospectively. The causative pathogens, clinical and laboratory characteristics of severity, antibiotic therapy and mortality were analysed. Immunocompromised patients, patients using immunosuppressive agents and patients with a malignancy were excluded.

Indices of severe illness were widely seen and 37% developed shock while 45% required vasoactive drugs. Bilobular or multilobular abnormalities were seen in 34% of the patients. Forty-five patients (73%) required artificial respiration and 54 (87%) had an underlying disease. The overall mortality was 42%. In 41 patients (66%), a pathogen was isolated. The most frequent causes of SCAP in this study were Streptococcus pneumoniae (22 cases or 35%), Haemophilus influenzae (seven cases or 11%), Pseudomonas aeruginosa (four cases or 7%), and other Enterobacteriaceae (twice in combination with pneumococci and once with H. influenzae). Legionella pneumophila was identified in three cases. In patients with severe chronic obstructive pulmonary disease (COPD), pneumococci were the most important pathogens six cases or 27%), followed by P. aeruginosa (14%) and H. influenzae (14%).

The guidelines for the management of SCAP issued by the ATS and IDSA in 1993 are only partially adequate in the Dutch setting. Coverage of P. aeruginosa would seem useful, given the fact that isolation of this pathogen has been shown to be a predictor of mortality, but only in patients with severe COPD or structural disease of the lung, and especially in patients in whom the Gram stain reveals Gram-negative rods, as is also suggested in the revised IDSA guidelines (1998). Risk factors for P. aeruginosa could be added to the ERS guidelines. Including SCAP as a separate entity in the SWAB guidelines may be useful.