Sulfonamide resistance in Neisseria meningitidis isolates of clones of the ET-5 complex

Abstract

A distinctive group of genetically closely related clones, as determined by multilocus enzyme electrophoresis, the ET-5 complex, has been responsible for an epidemic of meningococcal disease in Norway since the mid-1970's. Most isolates of the ET-5 complex from Norway are sulfonamide-resistant, serogroup B, and serotype 15:P1.16. Clones of the ET-5 complex that have been identified as the causative agents of recent outbreaks and epidemics in many other parts of the world show, outside Northern Europe, different associations of serotype protein antigens. We here report the analysis of sulfonamide susceptibility of isolates of the ET-5 complex from various geographic sources. There was no difference in resistance according to geographic source, serogroup, or serotype of the isolates, demonstrating that, in contrast to serotype and serogroup, sulfonamide resistance is an essentially invariant property of clones of the ET-5 complex.