The diagnosis of pneumococcal chest infection by counter-current-immunoelectrophoresis

Diagnostic testing for community-acquired pneumonia

The microbial cause of community-acquired pneumonia can be identified by noninvasive means in the majority of cases, usually within a few days of presentation. The Gram stain and culture of a pretreatment sputum sample are the most useful tests, but have significant limitations. Methods for detecting pneumococcal antigen in respiratory secretions are particularly helpful in patients who have received antibiotics before evaluation. Testing for specific pathogens such as L. pneumophila, M. pneumoniae, or C. pneumoniae should be guided by clinical suspicion in individual circumstances. Invasive procedures are most helpful in patients suspected of having infection with opportunistic or resistant pathogens, and in those whose initial management has been unsuccessful.

Rapid etiological diagnosis of pneumonia in young men

The major findings and conclusions of the present study are: 1. Evidence of the etiology of the pneumonia was established in 86% of 106 young men with pneumonia. Pneumococcus was the most common etiologic agent; it was detected definitely in 30% of the pneumonia patients, and possibly in another 20%, by blood culture, sputum culture, antigen detection, and serological methods. 2. Pneumococcal antigen detection from purulent pretreatment sputum samples was the best rapid diagnostic method for pneumococcus; it was capable of identifying 90% of the pneumococcal pneumonias definite by our criteria, whereas sputum Gram stain was positive in 65% of these. 3. Detection of adenoviral antigens from nasopharyngeal specimens (NPS) by EIA or IF method or adenovirus DNA by HYB method showed good specificity but a somewhat lower sensitivity than did adenovirus isolation from NPS. 4. Adenovirus antigens and DNA can be demonstrated also from sputum specimens. 5. EIA is slightly superior to the CF method in detecting antibody responses to adenovirus, but the detection of different antibody classes offers no additional diagnostic possibilities. 6. Isolation of Mycoplasma pneumoniae from bronchoalveolar fluid in pneumonia patients is a specific and sensitive method in the diagnosis of mycoplasmal pneumonia. 7. It seems possible to differentiate by clinical signs and symptoms and by high CRP (over 85mg/1) and WBC (over 10 x 10(9)/1) values pneumococcal pneumonias from viral, mycoplasmal and mixed pneumonias and from upper respiratory infections. Moderately elevated CRP values were observed in adenoviral (Mean 50 mg/1) and in mycoplasma (mean 59 mg/l) pneumonias, as well as in MRI (mean 44 mg/l).

Pneumonia in pediatric outpatients: cause and clinical manifestations

The cause and clinical manifestations of pneumonia were studied in 98 pediatric outpatients. A viral diagnosis was established in 38 (39%) of the 98 patients, and a bacterial diagnosis in 19 (19%). Ten (53%) of the 19 patients with bacterial pneumonia had a concurrent viral infection. No clinical, laboratory, or radiographic findings that would reliably differentiate viral from bacterial infection were identified. This study suggests that bacterial pneumonia is more common in pediatric outpatients than previously reported, and that the clinical, laboratory, and radiographic findings in patients with bacterial infection may be indistinguishable from findings in patients with viral infection.

Routine use of counterimmunoelectrophoresis for the detection of pneumococcal antigen in sputum

Sputum samples obtained routinely for culture from patients at a thoracic department were also examined for pneumococcal antigen by means of counterimmunoelectrophoresis (CIE), using a polyvalent antipneumococcal type serum (omniserum). Pneumococci were found in 1.3% of the 880 cultures, whereas pneumococcal antigen was detected with CIE in 6.5%. The validity of these findings was tested by correlating them with the presence of clinical symptoms in those with positive tests and also by antigen detection in ELISA using monoclonal antibodies specific for the C-polysaccharide common to all types of pneumococci. Clinical findings corresponding to confirmed or probable current chest infection were found in 36 of the 48 patients with positive CIE. ELISA was positive in 33 of the 38 patients with positive CIE who were tested. Although the study deals with an unselected material of chest patients, it indicates that CIE is a sensitive method and that it is independent of current antibiotic treatment. Pneumococcal infection is probably of importance in exacerbations of chronic obstructive lung disease, but the clinical usefulness of detecting pneumococcal and other antigens in this patient group needs to be studied further.

Diagnosis of pneumococcal pneumonia: a comparison between microscopic examination of expectorate, antigen detection and cultural procedures

Attempts to demonstrate Streptococcus pneumoniae, or its soluble type-specific polysaccharide antigen were made on specimens from 205 patients with acute community-acquired pneumonia by (i) blood, nasopharynx and sputum culture, (ii) counterimmunoelectrophoresis (CIE) of serum, urine and sputum specimens utilizing omni-, pool- and type-specific rabbit antisera, and (iii) microscopy of gram-stained sputum smears. Pneumococci could be cultured and/or pneumococcal antigen detected in specimens from 93 (45%) of the patients with the following frequencies in samples obtained before (and after) start of antimicrobial treatment: culture from blood 25% (6%), nasopharynx 59% (18%) and sputum 80% (13%), CIE on serum 3% (9%), urine 8% (18%), urine 20X concentrated 18% (24%), and sputum 56% (56%). Microscopy of sputum smears revealed pneumococci in 65% (17%) of the 93 patients. The value of cultures from blood and sputum was most evident when the samples were obtained early in the course of the disease. With nasopharynx culture and CIE on sputum the number of positive results was doubled if the sampling was repeated. For rapid diagnosis direct Gram stain and CIE on sputum were about equally effective and also strikingly complementary, alone diagnosing 42% and 48% of the patients, respectively, but together detecting 65% of them. Gram stain was most rewarding on early pretreatment samples and CIE on post-treatment samples.

Diagnosis of pneumococcal pneumonia by coagglutination and counterimmunoelectrophoresis of sputum samples

A comparison was made of the methods of coagglutination (using sensitized staphylococci) and counterimmunoelectrophoresis with regard to (i) sensitivity in detecting capsular polysaccharides from 14 different types of pneumococci, and (ii) sensitivity and specificity in detecting pneumococcal antigen in sputum samples from patients with pneumonia. Counterimmunoelectrophoresis was 20-150 times less sensitive than coagglutination in detecting purified type 7F and 14 polysaccharide preparations, and was as sensitive as or slightly more sensitive than coagglutination in detecting the other 12 polysaccharide types. Of 331 sputum samples examined, 94 were antigen positive, 87 by coagglutination and 76 by counterimmunoelectrophoresis; strong reactions were obtained with 85 and 63 samples, respectively. Moreover, with counterimmunoelectrophoresis 24 samples gave rise to probably non-specific precipitates, while with coagglutination either a strong positive or an unequivocally negative result was obtained in all but six samples. It is concluded that coagglutination is not only simpler and faster than counterimmunoelectrophoresis, but also appears to be more specific and sensitive for the detection of pneumococcal antigen in sputum samples.