Serological classification and genetic characterization of clinical isolates of Neisseria gonorrhoeae

Abstract: Bäckman, Marianne. Serological classification and genetic characterization of clinical isolates of Neisseria gonorrhoeae. Neisseria gonorrhoeae is the etiologic agent of gonorrhoea, one of the oldestand most widespread of human infections. The development of methods tocharacterize the bacterium is of central importance in the control of thedisease.One aim of this thesis was to evaluate serotyping of N. gonorrhoeae strainswith monoclonal antibodies directed to Protein I in a clinical setting. Thesubdivision of gonococcal isolates into serovars was stable with the GS panelof monoclonal antibodies tested. Serovar analysis using the coagglutinationtechnique is simple, rapid and does not require expensive equipment. It has abetter resolution than auxotyping and is well suited for routin-testing ofclinical samples.In a one year study in 1982 - 1983, N. gonorrhoeae strains of serogroupWII/III were more common than strains of serogroup WI. The serogroupswere not equally distributed among women, heterosexual men andhomosexual men. Different serovars dominated among strains fromheterosexual and homosexual patients. However, many of the serovarsconfined to only one of the subpopulations represented a small number ofisolates.Decreased susceptibility to multiple antibiotics was found in all serogroupWII/III transformants studied indicating a possible genetic linkage betweenthe por gene and locus/loci coding for resistance to antibiotics.The proportions of gonococcal strains with chromosomally mediatedresistance to tetracycline increased during 1982 - 1993, especially during thelatter part of the study. Gonococcal strains carrying tet(M) plasmids werefirst isolated in Sweden in 1991. The proportion of penicillinase producing N.gonorrhoeae isolates increased at Stockholm Söder Hospital 1982 - 1993. Theserovar analysis of N. gonorrhoeae strains carrying plasmids encoding forantibiotic resistance implies a minor spread of these strains in Stockholm.This emphasizes the importance of susceptibility testing of all N.gonorrhoeae isolates.PilC is a 110 kD pilus-associated minor outer membrane protein involved inthe biogenesis of pilus. The pilC gene of a N. gonorrhoeae strain isolatedfrom disseminated gonococcal infection showed 88% homology with pilC2 ofN. gonorrhoeae strain MS11 and 84% homology with pilCI of MS11. Tenvariable cassettes were identified. This suggests that PilC is a antigenicallydiverse protein. The pilC gene was also present in two other clinical isolatestested. The strains examined belonged to different serovars.Keywords: Neisseria gonorrhoeae, serotyping, antibiotic susceptibility,plasmid, pilC, auxotyping, fingerprinting, geographical originISBN 91-628-1851-1

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