[Research of the soluble microbial substances in organic fluids for the rapid diagnosis of some infections and particularly of bacterial meningitis (author's transl)].

A number of immunological and non-immunological techniques have been recently used to detect soluble microbial substances in body fluids of patients with acute meningitis, bacteremia, and lobar pneumonia. By the immunological methods capsular highly polymerized polisaccharide group- or type-specific antigens of the most common C. N. S. pathogens (N. meningitidis A, B, and C; Str. pneumoniae, H. influenzae type b, E. coli K1, mucoid Pseudomonas, Cryptococcus neoformans) can be detected and quantitated in spinal fluids, sera, urine and other fluids specimens from meningitic patients. Capsular type-specific antigens from pneumococcus, and likely from H. influenzae as well, can be detected in sputum from patients with lower respiratory infection. Among the various techniques, the radioimmunoassay appears as the most sensitive one, but high diagnostic sensitivity can be also achieved by using the latex agglutination, haemoagglutination inhibition and coagglutination tests. Counterimmunoelectrophoresis, however, is still the far most used technique for determining soluble microbial antigens, albeit its sensitivity is significantly less than the one of the above mentioned methods. High specificity and some advantages in serotyping the causal organisms are probably the main reasons of such preferential employment. Among the non-immunological techniques the evaluation of lactate and lactic dehydrogenase has been used by some Author for differentiating between bacterial and non bacterial meningitis, and the limulus test for detecting Gram-negative bacterial endotoxins with a high degree of sensitivity and specificity. Finally, the liquid gas chromatography has been evaluated in detection of some organic products (microbial?), such as acids, amines, neutral compounds, in spinal fluid, allowing the differential diagnosis between bacterial, tuberculous, viral, and cryptococcal meningitis. In the present review sensitivity, specificity, and other properties of each test alone and in comparison with the conventional microbiological methods (Gram and culture) are evaluated and the biological and pathogenic role and significance of the soluble microbial antigens and endotoxin are discussed.