An unusual Neisseria isolated from a case of meningitis

Abstract

Crystalline penicillin, 10,000 units, was given intrathecally, and this was followed by 125 mg penicillin V, six hourly for six days. 440Culture of cerebrospinal fluid on blood agar at 37°C in CO2 (candle jar) showed a scanty pure growth of a Neisseria colonially resembling N. meningitidis, and a blood culture taken at the same time yielded an organism which was apparently the same. Both organisms were sensitive to penicillin, ampicillin, chloramphenicol, streptomycin, and erythromycin.The day after admission his temperature had fallen to normal, although there was still marked neck stiffness, and a second lumbar puncture showed a cerebrospinal fluid pressure of 250 mm. Protein was now 100 mg per 100 ml and there were 6 polymorphs, 10 lymphocytes, and 4 RBCs per cu mm. Clinical improvement was maintained, and he was discharged 10 days after admission.STAGE 1 BACTERIOLOGICAL INVESTIGATIONS The organisms isolated from cerebrospinal fluid and blood both had the following characteristics when first examined. (We shall refer to these cultures as phase 1 for convenience in description.) They were oval or spherical Gramnegative diplococci of Neisseria type and were heavily capsulated. After 24 hours at 37°C on horse blood agar the colonies resembled those of classical N. meningitidis. After 12 hours' further incubation at 37°C, the colonies became rough and the organisms autolysed. Growth did not appear to be influenced by CO2. Subculture on a nutrient (Hartley's broth solidified by adding agar) agar slope at room temperature showed some growth after 24 hours. There was no change in glucose, saccharose, or maltose (serum agar slopes at 37°C). The isolates were oxidase and catalase positive. A saline suspension killed by heating at 60°C for one hour was not agglutinated by polyvalent meningococcus antiserum. STAGE 2 BACTERIOLOGICAL INVESTIGATIONS Of heavy suspensions in saline from overnight cultures on blood agar at 37'C, 0-5 ml aliquots were inoculated intraperitoneally into two white mice, one receiving the culture from cerebrospinal fluid, the other from blood. The mice were sacrificed 18 hours later and the organisms on 12 May 2018 by guest. Protected by copyright.