Neisseria meningitidis strains with decreased susceptibility to penicillin.

Neisseria meningitidis strains relatively resistant to penicillin were recovered from blood or cerebrospinal fluid cultures of four children treated in Barcelona, Spain, and surrounding areas. The four strains had distinct serogrouping and serotyping patterns. The minimal inhibitory concentrations of penicillin were 0.25 microgram/ml for three strains and 0.5 microgram/ml for the fourth strain. These are the first relatively penicillin-resistant meningococcal strains identified in Spain.