Legionella pneumonia as a cause of atypical pneumonia in a tertiary care hospital in Sri Lanka

Atypical pneumonia which contributes to an important proportion of community acquired pneumonia and Legionella pneumophila is a noteworthy pathogen worldwide. Legionnaires’ disease, the severe form of pneumonia is predominantly caused by Legionella pneumophila serogroup 1. This study was conducted to determine the presence of Legionella pneumophila as a pathogen and the associated risk factors among the patients admitted with atypical pneumonia to a tertiary care hospital in Sri Lanka. Seventy-five adult patients diagnosed with atypical pneumonia attending professorial medical unit of Colombo South Teaching Hospital, Sri Lanka were enrolled. Risk factors related to the disease was assessed by an interviewer administered questionnaire. Expectorated sputum was processed on supplemented buffered charcoal yeast extract medium and urine specimens were tested for Legionella pneumophila serogroup 1 antigen. Fifty-six percent of the patients were males and 91% were residing in urban areas. Smoking was admitted by 32% and that of alcohol consumption was in 25%. Composting and potting, distant travelling and frequent use of air conditioning was reported in 28%, 37% and 4% respectively. Majority of participants were not exposed to cooling towers, humidifiers or plumbing and not visited high risk areas. Among the study group, 21% had diabetes, 24% had ischaemic heart disease and 36% had chronic lung diseases. None of the sputum samples grew Legionella pneumophila, and all urine samples were negative for the antigen of Legionella pneumophila serogroup 1. It is concluded that, in this population of community acquired atypical pneumonia, Legionella pneumophila was not identified as a causative agent.