Legionella, Chlamydia pneumoniae and Mycoplasma infection in patients admitted to Christchurch Hospital with pneumonia

Aims. To determine the incidence, clinical features and outcome of communit y acquired pneumonia caused by Mycoplasma pneumoniae, Legionella species, C oxiella burnetti, Chlamydia pneumoniae and Chlamydia psittaci requiring adm ission to hospital. Methods. Over 12 months the clinical findings and severity of pneumonia wer e recorded prospectively. Sputum, blood, serum and urine samples were colle cted for diagnostic testing. Management was supervised by the admitting med ical team. Subjects were followed-up six weeks after discharge. Results. Two hundred and fifty-five patients met the entry criteria of whom 20 died, including five who had Legionella infection. M pneumoniae (16%) i nfection was more often of mild/moderate severity (95%), occurred in a youn ger age group (mean age 31.4 years, p=0.002), with more frequent myalgia an d headache. The length of hospital stay was shorter and clearing of chest r adiograph and return to normal activity occurred more rapidly in this group of patients. Legionellosis was common as judged by culture and serological testing (26 cases, 11%) and a further 22 cases were identified by polymera se chain reaction. Legionella infection was not distinguishable clinically from other pneumonias. C pneumoniae was uncommon (8 cases, 3%). C burnetti and C psittaci were not identified in this study. Conclusions. Some cases of pneumonia caused by Mycoplasma pneumoniae can be identified at presentation, however pneumonia due to Legionella is not dis tinguishable on clinical grounds. Development of molecular diagnostic techn iques may enable therapy to be directed against specific organisms earlier in the course of the disease.