title: Plasmid-mediated resistance to tetracyclines amongNeisseria gonorrhoeaestrains isolated in Poland between 2012 and 2013.
abstract: BACKGROUND
  One of two main mechanisms of resistance in tetracycline-resistantNeisseria gonorrhoeae(TRNG) is associated with the presence of TetM protein responsible for actively blocking of the tetracycline target site in the 30S ribosomal subunit. This mechanism is encoded by conjugative plasmids. The second mechanism is chromosomal in nature and due to mutations in specific genes.
  
  
  OBJECTIVE
  To determine the incidence and type oftetMdeterminants in TRNG strains isolated from patients presenting with gonorrhea infection to the Dermatology and Venereology Clinic in Warsaw in 2012-2013.
  
  
  METHODS
  Tetracycline and doxycycline susceptibility was determined by E-Tests. The presence and type of thetetMgene were determined by polymerase chain reaction.
  
  
  RESULTS
  Tetracycline resistance was detected in 50.8% of the evaluated strains. The TRNG strains containing thetetMplasmid constituted 13.8% of all the evaluated strains. Dutch typetetMconstituted 12.3% and American typetetM1.5% of all the evaluated strains. In the remaining TRNG strains, resistance to tetracyclines was presumably chromosome-encoded. The minimal inhibitory concentration (MIC) of tetracycline ranged from 0.25 to 32.0 mg/l, MIC50= 2.0 mg/l, MIC90= 32.0 mg/l. The MIC of doxycycline ranged from 0.25 to 32.0 mg/l, MIC50= 4.0 mg/l, MIC90= 16.0 mg/l.
  
  
  CONCLUSIONS
  Unlike most of European countries, in 2012-2013 in Poland, the Dutch typetetMwas found to be much more common than the American type. Minimal inhibitory concentration values of tetracycline and doxycycline were similar, with doxycycline exhibiting a somewhat lower effectivenessin vitrothan tetracycline towards chromosome-mediated tetracycline resistant strains ofN. gonorrhoeae.
authors.affiliation: Department of Diagnostics of Sexually Transmitted Diseases, Medical University of Warsaw, Warsaw, Poland.
authors.forename: Beata
authors.initials: B
authors.lastname: Młynarczyk-Bonikowska
authors.affiliation: Department of Medical Microbiology, Medical University of Warsaw, Warsaw, Poland.
authors.forename: Marlena
authors.initials: M
authors.lastname: Kujawa
authors.affiliation: Department of Diagnostics of Sexually Transmitted Diseases, Medical University of Warsaw, Warsaw, Poland.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Malejczyk
authors.affiliation: Department of Medical Microbiology, Medical University of Warsaw, Warsaw, Poland.
authors.forename: Grażyna
authors.initials: G
authors.lastname: Młynarczyk
authors.affiliation: Department of Dermatology and Venereology, Medical University of Warsaw, Warsaw, Poland.
authors.forename: Sławomir
authors.initials: S
authors.lastname: Majewski
keywords: Neisseria gonorrhoeae; tetM American type; tetM Dutch type; tetracycline resistance