[Detection of rifampicin-resistant strains of Neisseria meningitidis in Uruguay]. / Detección de cepas de Neisseria meningitidis resistentes a rifampicina en el Uruguay.

The objective of this study was to characterize the phenotype and genotype of two isolates of rifampicin-resistant Neisseria meningitidis associated with two independent events involving transmission of severe meningococcal meningitis that occurred in September and October 2010 in Montevideo, Uruguay. The most recent 10 years of data from the national antimicrobial resistance surveillance system were reviewed to estimate the frequency of the particular meningococcal features that were characterized. Rifampicin resistance was studied using the epsilometer test. The serotype and serosubtype of the isolates were determined by ELISA, and the genotype was characterized using DNA digestion with Nhel and pulse field gel electrophoresis. The two isolates were identical: B:2a:P1.5. In the collection of 408 strains of N. meningitidis isolated in Uruguay in the past 10 years, the phenotype only appeared in two isolates, which were sensitive to rifampicin. The two isolates studied also shared a single pulse type, which was different from that of two other rifampicin-resistant isolates obtained in 2003 and 2007. Consequently, it was concluded that both cases of transmission were caused by a single rifampicin-resistant strain, which could have been an import from another country or else the result of a drift from serogroup C to B due to selective pressure exerted by vaccines administered to the population. It is essential to maintain and maximize surveillance. However, since this type of finding has been sporadic so far, unless a secondary case is identified, there is no justification for changing the antimicrobial drug currently being administered to contacts as prophylaxis.