Discrepancies in fluorescent antibody, counterimmunoelectrophoresis, and Neufeld test for typing of Streptococcus pneumoniae.

The techniques of fluorescent antibody (FA) and counterimmunoelectrophoresis (CIE) were compared with the Neufeld test (quellung reaction) for typing of Streptococcus pneumoniae. A total of 88 isolates were examined by these three methods. Pool-, type-, or group-specific pneumococcal antisera were used in all three methods. Each isolate was initially tested with polyvalent antisera and all of the nine pools of antisera. Selection of the type- or group-specific antisera depended upon the reaction of the isolate with the pool sera. Sixty-eight of 88 (77.3%) isolates were positive using pool or typing sera and were correctly typed by CIE, while FA was found to be accurate for only 61 of 88 (69.3%) isolates. Positive reactions with more than one pool- or type-specific antisera, or no reaction, were seen with several of the isolates with both techniques. Even though CIE and FA are rapid and simple techniques, microbiologists should be cautious when utilizing them for typing of S. pneumoniae because of the discrepancies observed in this study.

Clinical features and laboratory diagnosis of rotavirus-associated gastroenteritis in infants and children.

PIP: This study was undertaken to compare countercurrent immunoelectrophoresis (CIE) and enzyme-linked immunosorbent assay (ELISA) using Rotazyme kit to detect rotavirus antigen in the stools of children with gastroenteritis and to compare and contrast the signs and symptoms of rotavirus antigen-positive with antigen-negative children. Over 2 years, 171 infant and children admitted to the pediatric in-patient unit at St. Luke's Hospital, Cleveland, Ohio, with gastroenteritis were evaluated. Stools from 108 (63%) had rotavirus antigen. In most patients, antigen was detected by both CIE and ELISA. 100 (94%) of the 108 patients were under age 2; 72 (66%) rotavirus-positive patients were seen during the colder months. Frequency and duration of diarrhea, presence and duration of vomiting, presence and duration of fever, and lack of examination findings distinguished the rotavirus antigen-positive from the rotavirus antigen-negative patients. CIE and ELISA are reliable, simple laboratory methods for identifying this etiologial agent in stool. Rotavirus antigen was detected by both CIE and Rotazyme technique in most patients. In a few patients only 1 test was positive for the antigen. In 16 (14.8%) positive specimens antigen only could be detected by CIE, while in 11 (10.2%) positive specimens the antigen was demonstrable only by the Rotazyme method. This discrepancy is hard to explain since both methods are sensitive and compare well with immune electron microscopy. CIE is an inexpensive, simple test which can be done easily in any microbiology or clinical laboratory, with the results ready in 3 hours. Rotazyme is very sensitive but it is also more complicated than CIE.^ieng