Bacteriocins (meningocins) in Norwegian isolates of Neisseria meningitidis: possible role in the course of a meningococcal epidemic.

In the Neisseria meningitidis strain MC58 (serogroup B; ET-5 complex) genome three putative islands of horizontally transferred DNA (IHTs) have been identified. IHT-A2 codes for eight hypothetical proteins and two disrupted open reading frames with similarity to a secretion protein (NMB0097) and an ABC transporter (NMB0098). The strains MC58 and 44/76 (shown here) are meningocin resistant/weakly sensitive.

Unusual antineisserial activity expressed by a systemic isolate of Neisseria meningitidis. antimeningococcal effect and properties.

Antineisserial activity expressed by the systemic Neisseria meningitidis strain 77/79A was studied using the cross-streaking technique. Of 271 meningococcal isolates tested, > 84% were sensitive to this strain. The degree of susceptibility was largely dependent upon the agent characteristics of the individual isolates.

Production, isolation and purification of bacteriocins expressed by two strains of Neisseria meningitidis.

The systemic Neisseria meningitidis strain P241 and the healthy pharyngeal carrier strain BT878 produce bacteriocin-like substances during growth. A method has been devised for obtaining the active substances in solution. The activity was recovered by freeze-thaw extraction of dialyzed Todd-Hewitt agar medium into which the bacteriocins had diffused during growth of the producer strains.

Bacteriocins in Neisseria meningitidis. Screening of systemic patient strains and pharyngeal isolates from healthy carriers.

Systemic meningococcal isolates and meningococci from healthy pharyngeal carriers in Norway were screened for production of growth antagonistic substances. Seven (4.9%) of a total of 142 systemic strains and 3 (2.

Activity of bacteriocin-like agents from Neisseria meningitidis on strains isolated from patients and carriers.

Strains of Neisseria meningitidis isolated from patients were more often completely insensitive to five bacteriocin-like agents than carrier strains, but no particular bacteriocin type could be associated with patient strains. Two genetically distinct types of insensitivity could be separated by transformation. Insensitivity to four bactericidal agents (from the strains P201, P213, P241 and 99/79) was caused by one common genetic marker whereas insensitivity to a bacteriostatic agent (from the strain 77/79) was caused by another.

Inhibitory spectrum of bacteriocin-like agents from Neisseria meningitidis.

Bacteriocin-like agents from five strains of Neisseria meningitidis were active against other meningococci and some other Neisseria species. Meningococci belonging to the same serogroup or serotype could be subdivided into distinct bacteriocin types. Insensitivity to the inhibitory agents was observed more frequently among serologically groupable strains than among non-groupable.

Influence of blood cells on the expression of bacteriocin-like activity in Neisseria meningitidis.

The inhibitors responsible for the bactericidal activity found in four strains of Neisseria meningitidis were strongly bound to or inactivated by blood cells. The bactericidal effects were specifically influenced by human cells of types O, A, B and AB. Cells from horse, sheep and rabbit had no significant effect.

Expression of bacteriocin-like activity in batch cultures of Neisseria meningitidis and consequences for genetic recombination.

The bactericidal activity found in four strains of Neisseria meningitidis and the bacteriostatic effect observed in one were expressed in the exponential phase of batch cultures and continued during the stationary phase. The active material was stable for more than 50 hours in agar media. In mixed cultures a strain with inhibitory activity eradicated a sensitive strain, and dominated the culture in the latter part of the exponential phase.

Three types of growth inhibition among strains of Neisseria meningitidis isolated from patients in Norway.

A survey has been made of Neisseria meningitidis strains isolated from patients in order to determine the prevalence of diffusible growth inhibitory substances active against other meningococci. Three types of growth inhibitory activity could be distinguished. The first type was release in cultures of nearly all strains after treatment with chloroform vapour.