Detection of endotoxinlike activity in cerebrospinal fluid by Limulus amebocyte lysate gelation has been suggested as a useful technique for the diagnosis of gram-negative bacterial meningitis. We prospectively screened 1,503 cerebrospinal fluid specimens with a Limulus amebocyte lysate microassay. The limit of sensitivity of the assay was 0.01 ng/ml. All specimens that were positive for endotoxinlike activity were subjected to confirmatory retesting, after which 38 (86%) remained positive. Comparison with available culture results revealed that 33 of 38 specimens (86%) were culture positive; 3 of the 5 culture-negative specimens were from patients on therapy for gram-negative becterial meningitis, and 1 was from a neonate. The overall specificity of confirmed positive tests was 99.5%, with a positive predictive value of 97.3%. There was one false-negative specimen, giving an overall sensitivity of 97.3% and a negative predictive value of 99.9%. Endotoxinlike activities of .150 ng/ml correlated with present illness of less than 2 days' duration (P = 0.024), elevated cerebrospinal fluid protein (P < 0.05), and seizures (P = 0.004); levels of .3,000 nglml correlated with neutropenia (P = 0.032), and levels of .3.2 x 106 ng/ml correlated with death (P = 0.001). We conclude that the Limulus amebocyte lysate microslide gelation test has prognostic value as a sensitive, specific, simple, inexpensive screening test for gram-negative bacterial meningitis.

Plasmid DNA was isolated and purified from a strain of Staphylococcus aureus demonstrating adherence to human epithelial cells, as determined by an assay quantitating adherence of radiolabeled S. aureus to HeLa cells in tissue culture. Other phenotypic characteristics of the donor strain are resistance to ampicillin and absence of hemolysis. A 23.5-kb (kilobase) plasmid was transformed into a nonadherent, ampicillin-sensitive, beta-hemolytic recipient of S. aureus, rendering it both ampicillin-resistant and adherent to a degree approaching that of the donor strain. Plasmid analysis of the donor and transformant strains revealed three identical EcoRI fragments of 7.6 kb, 6.5 kb, and 2.2 kb, together with a 3.6-kb EcoRI fragment in the transformant that demonstrated homology with the last 7.2-kb fragment in the donor. We conclude that an adhesin of S. aureus is encoded by this 23.5-kb penicillinase-encoding plasmid and that techniques of molecular genetics may be utilized to clarify the mechanisms of adherence of S. aureus.

The diagnostic efficacy of an enzyme immune assay to detect cytomegalovirus (CMV) antigen in the urine of infected infants and children was determined, and the effect that CMV-specific antibodies present in the urine have on the sensitivity of the test was ascertained. The antigen was detected in 84.4% of the CMV-culture-positive samples, while CMV-specific IgA was detected in 24% of CMV-culture-positive specimens. The absence of CMV-specific IgA correlated with detection of CMV antigen in the CMV-culture-positive urine specimens (p less than 0.05).

The prevalence of pharyngeal carriage of group B streptococci was evaluated in patients with and without the complaint of a sore throat by three methods (blood agar plates, Columbia CNA agar plates, and a selective enrichment broth containing gentamicin and nalidixic acid). The overall carriage rate of group B streptococci was 12%, and there was no significant difference between the two groups of patients. The selective broth medium was more sensitive than the two solid agar plate methods in detecting carriage, and 37% of all group B streptococci were recovered solely from the broth. Use of the broth alone would have permitted a 94% detection of the group B streptococcal carriers.