Background: Pneumonia is a common medical problem with a significant mortality and morbidity. It is the leading infectious disease in hospital admissions. We conducted a one year prospective study of the patients over 14 years of age that had been diagnosed of community-acquired pneumonia in our institution. The objective was to determinate the clinical characteristics and the aetiological agents of pneumonia in our geographic area and to know which factors are related with the evolution and prognosis of this disease.
Patients and methods: A medical team evaluated and followed-up all the patients diagnosed of community-acquired pneumonia. Epidemiological, clinical, radiological and laboratory data were recorded. An attempt to obtain an aetiological diagnosis was done by means of sputum, blood cultures and serologic studies at admission and between third and fourth week later. In individualized patients invasive techniques were performed. We classified the patients in five groups according to previous criteria defined in the guidelines of our hospital based in age, the presence of an underlying disease and the severity in the initial presentation.
Results: 274 patients received an initial diagnosis of pneumonia, in 76 (28%) this initial diagnosis was not confirmed. The mean age of the remaining 198 was 55 years. 62% were men. 40% had an identifiable microbiological etiology. The main causal microorganism was Streptococcus pneumoniae followed by Mycoplasma pneumoniae. Gram stain and sputum culture were the most useful laboratory tests for the aetiological diagnosis. Blood cultures and serological test had a lower efficiency. There was no relationship between the clinical presentation, typical or atypical pneumonia, and the causal microorganism. Complications developed in 11% of the patients and the mortality rate was of 3%.
Conclusions: There was a high rate of initial erroneous diagnoses of pneumonia. The epidemiological, clinical and roentgenographic characteristics were similar to other studies conducted in our country with a lower number of microbiological agents identified. Patients who were admitted at hospital only because their age or the presence of chronic disease had a good evolution. In this series patients with severe presentation also had a good prognosis. It would be interesting to investigate about which parameters could be useful as indicators of prognosis and evolution at initial presentation of pneumonia.