sYNoPsis The use of Counter immunoelectrophoresis (CIE) for the detection of pneumococcal capsular antigen in the sputum and serum of patients suffering from acute respiratory infections is described. The CIE of sputum gave positive results in 224 (99 %) out of 225 samples in which Streptococcus pneumoniae was isolated by cultural techniques, and in 23 (9 %) out of 262 samples in which no or other potential pathogens had been isolated. In the detection of capsular antigen in serum, CIE was positive in 32 (35 %) out of 92 pneumonia cases and was associated with an increase in mortality.In the clinical management of pneumonia where the patient receives antimicrobial therapy before the causal organism has been identified, a specific bacteriological diagnosis is frequently rendered impossible because of the growth of such replacement organisms as Escherichia coli and Klebsiella species (Spencer and Philp, 1973). Since the detection of antibodies or polysaccharide capsular antigens might be of value in this situation, the use of Electrosynerese (Bussard, 1959), a development from the technique of Lang and Haas (1957), or Counter immunoelectrophoresis (CIE), as it is more commonly termed, has been investigated. The present report is primarily concerned with the diagnostic and prognostic use of this technique in pneumonia due to Streptococcus pneumoniae.
Patients and Methods
PATIENTSA group of 225 consecutive patients, in whom Str. pneumoniae had been isolated from the sputum as the potential pathogen, was balanced with a control group of 262 patients from whom another or no potential pathogen had been isolated. The first group was subdivided into three categories: (1) patients with clinical pneumonia confirmed by chest x-rays, (2) patients with exacerbations of chronic lung diseases, eg, bronchitis, asthma, and Received for publication 6 August 1975 bronchiectasis, and (3) surgical postoperative patients who had developed a productive cough but did not fall into the previous two categories.
SAMPLESSputum and serum were collected from the patients as soon as the clinical diagnosis had been made. The sputa were cultured on blood agar under carbon dioxide at 37°C. These were read after overnight incubation, and potential pathogens were identified by standard methods (Cowan and Steel, 1974). Very small numbers of potential pathogens found only in the inoculation well were not regarded as significant.
IMMUNOELECTROPHORESISCounter Immunoelectrophoresis (CIE) This was performed with a method based on that of Dorff et al (1971). The stock buffer used was barbitone/sodium barbitone, pH 8-2, and microscope slides were covered with 0 9% agarose (Miles-Seravac Ltd, Maidenhead, Berks) in halfstrength buffer sufficient to give a depth of 1 mm of agarose. Ten ,ul amounts of antibody or test fluid were employed and a constant voltage of 20 V per cm was applied for one hour at room temperature. After electrophoresis the gel was washed in 5% sodium citrate for 15 minutes and examined by reflected light for lines of precipitation. Ge...