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The aim of this study was to investigate the Neisseria meningitidis carriage rate among two cohorts of Polish recruits upon entry to the military and during the first 2 months of their service, i.e. in the spring and autumn of 1998, and to characterize the meningococcal strains isolated. Pharyngeal swabs were taken four and five times from 151 and 168 men, respectively. Altogether, 81 and 180 meningococcal isolates representing 54 and 102 different strains were recovered. The overall rates of carriage in the spring and in the autumn were 36% and 61%, and, among recruits who submitted to sampling on at least three occasions, 39% and 55%. Eighty-three of 156 (53%) meningococcal carrier strains were nongroupable; among the remaining strains, serogroup B was predominant (32% of all carrier strains). In both surveys the predominant phenotype was Neisseria meningitidis NG:21:P1.7.

The aim of this study was to investigate the genetic relationships among strains belonging to Neisseria meningitidis serotype 22 recovered in Poland from 1995 to 1998. Phenotypical characterisation of meningococcal strains isolated from patients with meningococcal disease has been performed since 1995. Strains belonging to Neisseria meningitidis type 22 were most frequently recovered from severe cases of meningitis and septicaemia. The type 22 strains were separated into clusters by serosubtyping and DNA analyses by pulsed-field gel electrophoresis and ribotyping. However, the grouping according to serosubtypes was quite different from that obtained by ribotyping and pulsed-field gel electrophoresis. Furthermore, the two genotyping methods seldom identified the same clusters, nor were clusters identified among 26 Neisseria meningitidis type 22 strains recovered from patients hospitalised in five cities. Determination of the susceptibility to penicillin showed that a single strain was resistant (MIC, 2 mg/l) and that one-third (24/71) of the strains tested had reduced susceptibility (MIC range, 0.1-1 mg/l).

Phenotype and genotype identification of 179 Neisseria meningitidis strains isolated from cerebrospinal fluid or blood of patients with meningococcal infection, hospitalized in Poland, was performed. This is the first analysis of that type conducted in Poland. We analyzed strains collected in 1995-2000 from laboratories located all over the country. Phenotype Neisseria meningitidis B:22:P1.14 was the predominant among analyzed invasive strains in Poland. Type 22 is characteristic to most of the strains isolated in our country. No strain from analyzed group belonged to known epidemic clusters. One penicillin resistant strain (MIC = 2 mg/l) and about 27% strains with decreased susceptibility to penicillin (0.1 = < MIC < 1.0 mg/l) were present among 166 N. meningitidis tested. All strains were susceptible to ciprofloxacin and rifampicin.

No N. meningitidis strain was isolated from 168 children 14 years old. However, among 17-19 years old young people 14% meningococcal carriage rate was demonstrated. In three surveillance trials performed in military units in spring 1998 and autumn 1998 and 1999; 81, 225 and 153 isolates of N. meningitidis, respectively were obtained. A change in N. meningitidis carrier status was observed. At the autumn study, two times more N. meningitidis intermittent carriers were found than in the spring investigations. Among these population we found short-term and long-term carriers--last day of the longest trial--162 day. Meningococcal carriage rate increases among recruits in overcrowded living conditions.

Neisseria meningitidis carriers strains were isolated from 17-19 teenagers (n = 14) and recruits (n = 267). The longitudinal study comprises three meningococcal carriage trials performed on healthy young men during two--six months of their service in Polish military units. Altogether 54, 124 and 89 meningococcal strains were obtained during spring 1998 and autumn 1998, 1999 trials. Sixty two percent of meningococcal carrier strains were non-groupable, however among the remaining strains, serogroup B was predominant (29.5%). During spring 1998 and autumn 1999 trials the predominant phenotypes were N. meningitidis NG:21:P1.7, but during the autumn 1998 NG:21:P1.7 or NG:NT:P1.5. Ribotyping of type 21 and/or subtype P1.7 strains (n = 27) showed presence of 2 main ribotypes. Pulsed Field Gel Electrophoresis of consecutive isolates recovered from the same carrier showed great similarity of the patterns.