A prediction model for community-acquired Chlamydia pneumoniae pneumonia in hospitalized patients.

BACKGROUND: The objective of the study was to identify factors that help to predict community-acquired Chlamydia pneumoniae pneumonia in hospitalized patients. PATIENTS AND METHODS: Clinical data of 83 patients with serologically confirmed C. pneumoniae pneumonia were compared with the data obtained from 72 patients with bacterial pneumonia. The criteria of bacterial pneumonia included positive blood and/or sputum cultures and negative serology for Mycoplasma pneumoniae, Chlamydia psittaci, Chlamydia pneumoniae and Coxiella burnetii. The data collected included demographics, chronic diseases, pre- and post-hospitalization course of pneumonia, clinical data on admission and laboratory findings. Descriptive statistical analysis, involving numerous variables, was followed by univariate and multivariate logistic regression analysis. RESULTS: Two different situations, one including demographic data and information on the pre-hospitalization course of pneumonia, and another based on clinical information on admission and on laboratory results, were modeled using multivariate logistic regression. Several variables selected from these two models were incorporated into the third model, and the following four variables were found to have the highest predictive value of C. pneumoniae pneumonia: nursing home residence (odds ratio [OD] 3.73, 95% confidence interval [CI] 1.39-10.06), low c-reactive protein (CRP) levels (OD 5.99, 95% CI 1.82-19.67), nonproductive cough (OD 0.32, 95% CI 0.14-0.73), and a normal urinalysis (OD 0.38, 95% CI 0.17-0.83). CONCLUSION: Our findings seem to allow for a more reliable differentiation between C. pneumoniae pneumonia and other bacterial pneumonias, but further investigations will be needed to validate the proposed model.

Polymerase chain reaction for detection of Legionellae DNA in urine samples from patients with community-acquired pneumonia.

Polymerase chain reaction (PCR) was used for detecting Legionella DNA in water, sputum, tracheal aspirate and bronchoalveolar lavage fluid. There is paucity of data on the use of PCR for detection of Legionella in serum and urine samples. In 82 patients admitted with community-acquired pneumonia, urinary PCR was used in addition to urinary antigen assay for Legionella pneumophila serogroup 1 and serological tests (indirect immunofluorescence and ELISA) in paired sera. PCR was positive in urine samples from 21 patients (26%): in six of seven patients with acute legionellosis by CDC criteria, and 15 patients with negative urine antigen showing no fourfold rise in antibody titers in immunofluorescence test.

Microbial aetiology of community-acquired pneumonia in hospitalised patients.

Adult patients hospitalised with community-acquired pneumonia were studied prospectively to determine the microbial aetiology of pneumonia. Between April 1996 and March 1997, blood and sputum samples were collected for culture. Throat swabs were obtained for isolation of viruses and for detection of antigens of Chlamydia pneumoniae, influenza viruses A and B, respiratory syncytial virus and parainfluenza virus. Antibodies against Legionella spp., Mycoplasma pneumoniae, Chlamydia pneumoniae, Chlamydia psittaci, Coxiella burnetii, influenza viruses A and B, respiratory syncytial virus, adenovirus and parainfluenza virus were tested in serum samples. Two hundred eleven patients were included in the study; paired sera were available from 152 patients. Blood culture was positive in 23 (10.9%) patients, Streptococcus pneumoniae being the bacterium isolated most frequently. A fourfold or greater rise or fall in the Chlamydia pneumoniae IgG and/or IgM antibody titre was found in 20 (9.5%) patients and a high antibody titre (> or = 1:512) in the first and/or the second serum sample in 18 (18.5%) patients. Antibodies confirming acute Mycoplasma pneumoniae infection were found in 12 (5.7%) patients, Legionella spp. in six (2.8%), Chlamydia psittaci in two and Coxiella burnetii in one. Three patients had pulmonary tuberculosis. Only two patients had a virus present in the throat swab (adenovirus in one patient and echovirus in the other), and in nine patients, viral antigen was detected. Acute viral infection was confirmed in 51 (24.1%) patients. Bacterial pneumonia was diagnosed in 84 (39.8%) patients, 23 of whom had concurrent viral infection. Acute viral pneumonia without any other identified pathogen was diagnosed in 28 patients. Streptococcus pneumoniae and Chlamydia pneumoniae were the most frequently identified microorganisms.

Comparison of serologic tests with urinary antigen detection for diagnosis of legionnaires' disease in patients with community-acquired pneumonia.

OBJECTIVE: To compare serologic methods and detection of urinary antigen in the diagnosis of community-acquired pneumonia. METHODS: Paired sera from 84 patients with community-acquired pneumonia were tested for Legionella pneumophila serogroup (LP SG) 1-7 and Legionella micdadei by use of the indirect immunofluorescence antibody test (IIF), enzyme-linked immunosorbent assay (ELISA) for LP SG 1-7 and complement-fixation (CF) test for LP SG 1. All patients were evaluated by ELISA urinary antigen detection for LP SG 1. RESULTS: Seven patients met the CDC criteria for acute Legionella infection, while in the rest of them we failed to detect urinary Legionella antigen. Thirty-three patients had non-diagnostic IIF antibody titers. Serum ELISA (IgG and/or IgM) was positive in 40 patients. Nine patients showed at least one CF titer of >/=1:32. The sensitivities of ELISA IgM for the first and the second serum samples compared with IIF were 42.8% and 46.6%, respectively, while the specificities were higher, i.e. 87% and 88.4%, respectively. The sensitivities of ELISA IgG for the first and the second samples were 42.8% and 53.3%, and the specificities were 77.9% and 76.8%, respectively. CONCLUSIONS: Although ELISA is simple to perform and easy to automate, we think that its advantages over indirect immunofluorescence and urinary antigen detection remain questionable.