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Coagglutination for detection and serotyping of bacterial antigens: usefulness in acute pneumonias
Abstract:
Staphylococcal coagglutination was evaluated for detection of Streptococcus pneumoniae and Haemophilus influenzae antigens in vitro and in the clinical setting of acute pneumonia. Coagglutination testing was performed with Phadebact reagents and with polyvalent and type-specific reagents for pneumococci prepared in the laboratory. Purified capsular antigens of 10 of 14 pneumococcal serotypes (included in the current pneumococcal vaccine formulation) were detected by coagglutination in the range of 0.5-62 ng/ml; serotype 6 was detected at 125 ng/ml, and serotypes 12, 23, and 25 were detected only at 500 ng/ml or more. Haemophilus influenzae type b antigen was detected at 100 ng/ml. Sputum, blood, and urine specimens of 36 consecutive patients admitted with pneumonia were evaluated prospectively by coagglutination. Nonspecific reactions were eliminated by pretreatment with ethylenediaminetetra-acetic acid and heating and with staphylococcal protein A. Eight of nine patients with sputum cultures positive for pneumococci had positive sputum coagglutination (sensitivity of 89%); 24 of 27 patients with cultures negative for pneumococci had negative sputum coagglutination (specificity of 89%). Serum or urine coagglutination was positive in five patients with pneumococcal pneumonia, including the only bacteremic case, the only fatality, and another patient who had a protracted clinical course. In conclusion, coagglutination is a simple, rapid, sensitive, and specific test for antigen detection in patients with acute pneumonia.
Insights
Staphylococcal coagglutination offers a rapid and accurate method for detecting Streptococcus pneumoniae and Haemophilus influenzae antigens in acute pneumonia patients. This simple test demonstrates high sensitivity and specificity in clinical settings.
Area of Science:
- Clinical Microbiology
- Immunodiagnostics
- Infectious Diseases
Background:
- Acute pneumonia diagnosis often relies on culture methods, which can be slow.
- Rapid and accurate detection of bacterial antigens is crucial for timely treatment.
Purpose of the Study:
- To evaluate staphylococcal coagglutination for detecting Streptococcus pneumoniae and Haemophilus influenzae antigens.
- To assess the test's efficacy in vitro and in patients with acute pneumonia.
Main Methods:
- Coagglutination testing using commercial and laboratory-prepared reagents.
- Evaluation of purified pneumococcal and Haemophilus influenzae type b antigens in vitro.
- Prospective analysis of sputum, blood, and urine specimens from pneumonia patients.
Main Results:
- In vitro detection limits ranged from 0.5-500 ng/ml for pneumococcal serotypes and 100 ng/ml for H. influenzae type b.
- Sputum coagglutination showed 89% sensitivity and 89% specificity for pneumococcal detection.
- Positive coagglutination in serum or urine correlated with severe cases, including bacteremia and fatality.
Conclusions:
- Staphylococcal coagglutination is a simple, rapid, sensitive, and specific method for antigen detection in acute pneumonia.
- The test aids in the early diagnosis of bacterial pneumonia.
- Coagglutination can be a valuable tool in the clinical management of pneumonia.