A studyof Long-term Duration and Multiple Carriage of Neisseria meningitidis in HealthyPopulation by Molecular Biology Methods

Overview

The aim of the study was to investigate the long-term duration and multiple carriage of Neisseriameningitidis in a healthy population. In this prospective study, 206 students at the age of 15 to 19years were monitored from October 2002 to March 2003. Nasopharyngeal and laryngeal swabs weresampled in one-month intervals and cultured on a selective medium. All colonies detected in primaryculture were saved for the study, a maximum of 20 colonies in cases of massive growth. A total of1.242 isolates were obtained, all of them being examined by a molecular biology method RAPD(randomly amplified polymorphic DNA analysis). By other methods (determination of phenotype byslide agglutination and whole-cell ELISA test, the determination of sequence type, ST by multilocussequence typing, testing of susceptibity to antibiotics) were always tested the first isolates fromindividual carriers and isolates from the same carrier with different RAPD characteristics, being35 altogether. There were thirty three carriers of N. meningitidis detected among the 206 students(16%). The carriage of N. meningitidis was of long-term duration. The study of strains of N. meningitidiswith molecular biology methods made it clear that the carrier population of meningococciis heterogeneous. The population of carrier meningococci was of clonal character and mostlynon-virulent ST-complexes were detected. Multiple carriage of different clones of N. meningitidis israre and usually of short-termduration.The colonization of upper respiratory tract by a single cloneof N. meningitidis does not protect from colonization by other clone.

Key words:
carriage of Neisseria meningitidis – population of Neisseria meningitidis – RAPD – MLST.