[Pneumonia in maintenance hemodialysis patients: detection rate of causative organisms in sputum varies with time of sampling and quality].

PURPOSE: Previous studies have demonstrated that almost half the deaths caused by infection in hemodialysis patients are due to pneumonia. Causative organisms in pneumonia are not defined. We assessed the positive rate of blood and sputum cultures in a cohort of dialysis patients admitted with pneumonia. METHODS: We retrospectively enrolled 44 consecutive pneumonia patients on maintenance hemodialysis attending on outpatient clinic at a single department of nephrology between October 2005 and March 2013. Pneumonia was defined by the chest computed tomography findings and clinical status. The severity of pneumonia was scored using the pneumonia severity index (PSI) and the presumed causative organisms were identified. RESULTS: Among the 44 subjects, median age was 74 (interquartile range, 68-78) years, 90.9% were men, 28.4% had chronic obstructive pulmonary disease, and 61.4% had diabetes mellitus. Almost all patients (95.5%) were class IV or V on PSI. Blood cultures were all negative, but 36.4% of sputum cultures were positive for causative organisms. The most common pathogens were Staphylococcus aureus (13.6%), Pseudomonas aeruginosa (6.8%), Escherichia coli (4.5%), and Chlamydophila pneumonia (4.5%). The detection rate of causative organisms was related to the quality of the sputum (Group 4 and 5 of the Geckler classification) and was 61.5% in samples collected before dialysis on a day of dialysis, and 36.8% in samples collected on the day before a day of dialysis. In contrast, the detection rate was low (16.7%) when the samples were collected after dialysis on a day of dialysis. CONCLUSION: In hemodialyis patients, the detection rate of causative organisms is elevated if sputum samples are collected before undergoing dialysis on a day of dialysis. Prospective confirmation in a larger number of patients is warranted.