Prevalence of maltose-negative Neisseria meningitidis variants during an epidemic period in Spain.

We studied the prevalence of maltose-negative variants of Neisseria meningitidis in Spain from 1978 to 1980. Sugar utilization studies were performed with both CTA medium and Mueller-Hinton medium; bromothymol blue was used as the indicator in Mueller-Hinton medium. Of 1,714 isolates of N. meningitidis recovered from the cerebrospinal fluid or blood of patients with meningococcal infections, 64 (3.7%) were maltose-negative variants; 13 (3.3%) of the 363 isolates found in carriers had the same characteristic. All maltose-negative cultures isolated from both patients and carriers belonged to serogroup B and were resistant to sulfadiazine at a minimal inhibitory concentration, 10 micrograms/ml or more. Serotype 2 isolates were the most prevalent isolates in patients (68.8%), followed by nontypable isolates (20.3%). Only serotype 2 isolates (66%) and nontypable isolates (33%) were found in carriers.