Community-acquired pneumonia in Christchurch and Waikato 1999-2000: microbiology and epidemiology

Aims. To prospectively record current epidemiology and microbiology of comm unity-acquired pneumonia in two New Zealand centres. Methods. Between July 1999 and 2000 all adults admitted to Christchurch and Waikato Hospitals with community-acquired pneumonia were screened for stud y inclusion. All those enrolled had their medical history, clinical variabl es, inpatient management and clinical outcomes recorded and standardised mi crobial diagnostic testing carried out. Results. 474 participants were enrolled with a mean age of 64 years and a m icrobial diagnosis was made in 197 cases (42%). Streptococcus pneumoniae (1 4%), Haemophilus influenzae (10%) and Influenza A virus (7%), Legionella sp p (4%) and Mycoplasma pneumoniae (3%) were the most commonly isolated organ isms. An 'atypical' organism was diagnosed in 8% of cases compared to 30% a nd 23% in previous Christchurch and Waikato studies respectively. Fourteen of the 67 S pneumoniae isolates (21%) had reduced susceptibility to penicil lin, all with a MIC less than or equal to 2 mug/mL, a level of reduced susc eptibility not associated with worse patient outcomes. Clinical outcome inc luded a mean hospital stay of 6.7 days and a 6 week mortality of 6%. Conclusion. Although S pneumoniae was the most commonly isolated organism i n this study there have been significant changes in the prevalence of atypi cal organisms since previous surveys. Ongoing surveillance of antibiotic re sistance and variations in the prevalence of organisms causing community-ac quired pneumonia is required to guide clinicians' empiric antibiotic use.