USEFULNESS OF THE DNA-FINGERPRINTING PATTERN AND THE MULTILOCUS ENZYME ELECTROPHORESIS PROFILE IN THE ASSESSMENT OF OUTBREAKS OF MENINGOCOCCAL DISEASE

The objective of the study was to assess whether genotypic characteriz ation by means of DNA-fingerprinting pattern (DFP) and multilocus enzy me electrophoresis (MEE) profile as compared to phenotypic characteriz ation would improve the differentiation of Neisseria meningitidis stra ins associated with outbreaks from strains associated with sporadic ca ses of meningococcal disease. In addition, the differentiation of sero group C carrier strains from those associated with an outbreak of sero group C meningococcal disease was investigated. A total of 118 N. meni ngitidis strains were available for the study: 59 from patients involv ed in outbreaks of meningococcal disease (2 serogroup B and 2 serogrou p C), 37 from patients considered to be sporadic cases and 22 serogrou p C carrier strains. Among the 59 strains from patients involved in ou tbreaks the 4 strains isolated from the patient registered as the firs t in each outbreak were designated the index strains. Among the remain ing 55 outbreak strains 52 were either DFP-identical or DFP-indistingu ishable when compared with the one relevant out of the 4 index strains . This was only the case for 17 of the 37 strains isolated from sporad ic cases caused by the same serogroup of meningococci during the outbr eak periods, and 5 of the 22 meningococcal strains isolated from healt hy carriers. Among the 56 (52+4) DFP-identical or DFP-indistinguishabl e outbreak strains 5 different electrophoretic types were identified b y MEE. Among 59 assumed outbreak strains a total of 4 were identified as genotypically distinct. Among the 37 mainly DFP-indistinguishable o r DFP-different strains from sporadic cases 17 different ETs were iden tified, and among the 22 mainly DFP-different carrier strains 13 diffe rent ETs were identified. Two strains among those selected from sporad ic cases were identical to the outbreak strain. None of the local sero group C carrier strains isolated during the outbreak of serogroup C di sease were identical to the outbreak strain. Both DNA-fingerprinting a nd MEE improved the differentiation of meningococci when compared with phenotypic characterization. The results indicate that tracing a viru lent strain within an open group of contacts is irrelevant.