Eirik Holten

Virulence Markers in Patient and Carrier Strains of Neisseria meningitidis

Patient and carrier strains of Neisseria meningitidis from 2 different periods were compared with respect to serogroups, serotypes and sensitivity to sulphadiazine. The majority of 249 patient strains were resistant to sulphadiazine, and belonged to the groups A, B or C. The group B and C strains were mainly type 15/16 and 2, respectively. In contrast, most of the 400 carrier strains belonged to serotypes other than 2 or 15/16, or were non-typable, and most strains were sensitive to sulphadiazine. Among the resistant group B and C carrier strains there were more type 2 and 15/16 strains than would have been expected from the average. The virulence markers: serogroup A, B and C, serotype 2 and 15/16, and resistance to sulphadiazine, coexist in more carrier strains than would be expected if the distribution of these markers was random.

Radiorespirometric studies in genus Neisseria. 2. The catabolism of glutamate and fumarate.

The catabolism of glutamate and fumarate was studied by radiorespirometry in selected Neisseria species. The tricarboxylic acid cycle is functioning in all species tested, in spite of the known absence of in vitro malate dehydrogenase activity in N. meningitidis, N. gonorrhoeae and N. cinerea. The results imply a pyridine nucleotide independent oxidation of malate. The oxidation of glutamate is less complete in the presence of phosphate. In N. meningitidis, N. perflava, N. flava, N. subflava and N. lactamica the catabolism of fumarate was slow and incomplete in the absence of glutamate.

Bactericidal Activity in Sera from Carriers of Sulphonamide-Resistant Meningococci

Abstract During the winter 1969 a small epidemic of meningococcal meningitis occurred in a naval training centre in Norway. After sulphonamide prophylaxis most of the meningococcal strains isolated from throat cultures from the recruits were resistant to sulphonamides (8, 9). Serological studies were undertaken in 43 of the recruits, of whom 72% were found to be carriers of meningococci on at least one occasion. All these isolated strains were resistant to sulphonamides. In paired serum specimens, taken at the beginning of the epidemic and 6 weeks later, no increase in bactericidal antibodies against 4 meningococcal test strains belonging to the serogroups A, B, C, and Y was demonstrated. Against meningococcal strains isolated from the recruits themselves, however, a significant rise in titre was found, indicating that the recruits had been infected at about the same time as the first serum specimen was taken. In 26 members of the permanent staff, 2 of them carriers of meningococci, the bactericidal titres were about equal to those in the recruits. Thus, the lower carrier rate in the permanent staff does not seem to be due to increased bactericidal potency of the serum.

Endotoxin Release from Invasive Meningococci Related to Sulfonamide Resistance, Serogroup and Serotype

The relationship between endotoxin liberation, sulfonamide resistance, serogroups and serotypes was studied in 28 Neisseria meningitidis strains isolated from patients with meningococcal disease. Sulfonamide resistance was present in 15/28 strains. 22 strains belonged to serogroup B, and 5 to group C; 1 strain was non-groupable. Free endotoxin activity in growing cultures of meningococci with endotoxin titre of greater than or equal to 10(2) was found in 27/28 strains. A high endotoxin activity was present in both sulfonamide-sensitive and -resistant invasive meningococci. A high endotoxin release with titre greater than or equal to 10(3) seemed to be more associated with serogroup C than B, and more to the serotypes 2 and 15/16 than to the non-typable strains.