Background: in Chile, all systemic infections caused by Neisseria meningitidis must be reported and the bacterial strain must be sent to a Reference Laboratory at the Instituto de Salud Pública de Chile (ISP).
Aim: to report the characterization of strains of N. meningitidis isolated during systemic infections in Chile during the years 1992 and 1993.
Methods: the serogroup, serotype, subtype and antimicrobial susceptibility of every strain of N. meningitidis received at the ISP during 1992 and 1993 was studied.
Results: six hundred twenty eight strains of N. meningitidis were confirmed during 1992 and 1993. B serogroup was responsible of 91.1% and 94.7% of confirmed cases during 1992 and 1993 respectively. Serotypes and subtypes most frequently associated to B serogroup were B: 15: P1.3 (63.2%) in 1992 and 51.8% in 1993) and B:NT:P1.3 (11.7% in 1992 and 21.3% in 1993). In 1992, all strains were susceptible to penicillin, chloramphenicol, ceftriaxone and rifampicin. During 1993, 7 (2%) strains were found, for the first time in Chile, moderately susceptible to penicillin and rifampicin MIC90 increased fourfold in respect of 1992, although all strains continued to be susceptible to this antimicrobial.
Conclusions: the increasing frequency of NT (non typified strains) isolation will demand the use of molecular biology techniques for their identification. The appearance of penicillin resistant strains in our country is worrisome.