Epidemic spread of at least one prolyliminopeptidase-negative Neisseria gonorrhoeae strain in Denmark

Abstract number: 1134_02_24

Friis-Møller A., Berthelsen L., Germer U., Krogdahl H., Fredlund H., Unemo M.

Since the year 2002 isolates of prolyliminopeptidase (PIP)- negative Neisseria gonorrhoeae (GC) have been diagnosed in Denmark especially from men, who have sex with men. Species confirmation of GC is commonly based on enzymatic reactions in commercial kits such as API NH, RapID NH, Gonocheck II and Neisseria PET, which among other reactions rely on a biochemical identification of the enzyme prolyliminopeptidase.

Objectives:

To phenotypically and genotypically characterize a selection of PIP-negative GC isolates in Denmark and to investigate the possibility of a spread of one or several PIP-negative strain in the Danish community from 2002 to 2004.

Methods:

Twenty-five PIP-negative GC isolated in Denmark from 23 male patients between 2002 and 2003 were genetically characterized by means of DNA sequencing of the entire porB gene and pulsed-field gel electrophoresis (PFGE) with the restriction enzymes SpeI and BglII. Phylogenetic tree was constructed with TREECON v1.3b by using neighbor-joining method. Phenotypic characterization was performed by serovar determination of the 25 isolates and antibiotic susceptibility testing of all Danish GC strains isolated in 2002–2004 (n = 953). Clinical and epidemiological data were obtained when possible.

Results:

The 25 PIP-negative GC isolates were all designated as serovar IB-4 and similar MIC values were identified in the antibiograms of these isolates fingerprints were identified using SpeI and three using BglII among the 25 IB-4 isolates. Four distinguishable PFGE . However, all these isolates differed by less than six bands in both fingerprints. The phylogenetic tree analysis of the porB1b sequences, suggested that these minor differences represented the ongoing evolution of the same strain. During the period Jan. 2002 to Nov. 2004 the proportions of PIP-neg GC per year in Denmark were 15/332, 47/261 and 27/360, respectively, and the PIP-neg GC infected mostly men (only 5 women). The antibiograms of all Danish isolates 2002–2004 indicate a spread of at least one PIP-neg GC strain.

Conclusions:

The results of the present study indicate a circulation of at least one N. gonorrhoeae prolyliminopeptidase-negative strain in the Danish homosexual community. An increased awareness for PIP-negative N. gonorrhoeae, which create large problems in diagnosis using e.g. API NH, RapID NH, Gonocheck II or Neisseria PET, is essential.