Detection of a novel Tet M determinant in tetracycline-resistant Neisseria gonorrhoeae from Uruguay, 1996-1999.
BACKGROUND
Determination of the diversity within the tet(M) sequence from N gonorrhoeae is a useful epidemiologic tool for monitoring the movement or importation of strains within a geographic region. Only two distinct tet(M) genes in clinical gonococcal isolates have been described up to now: the Dutch and the American types.


OBJECTIVE
The study involved surveillance of the tet(M) gene types in high-level-tetracycline-resistant gonococcal isolates from Uruguay during the period 1996 to 1999.


METHODS
Among 181 gonococcal isolates, those showing MICs >/=16 microg/ml to tetracycline were analyzed for detection and characterization of the tet(M) gene by a polymerase chain reaction (PCR) and further HpaII restriction fragment polymorphism methods, respectively. The plasmid content and antibiogram were determined.


RESULTS
Twenty-two of 181 isolates (12%) exhibited high levels of resistance to tetracycline (MICs >/=16 microg/ml) and harbored a putative 25.2-Mda plasmid that contained the tet(M) gene. A high percentage of isolates (95%; 21/22) presented the Dutch type tet(M) gene. One isolate from 1999 revealed a new restriction pattern. Such a pattern had been previously noted in 1991. This new restriction pattern has not been described previously as occurring in isolates of N gonorrhoeae. The tet(M) amplimer sequence showed 100% identity with a previously described tet(M)-carrying plasmid from N meningitidis.


CONCLUSIONS
A new HpaII restriction pattern of the tet(M) gene is present in low frequency. The tet(M) sequence was different from the gonococcal tet(M) sequences already known and not typable with the use of a differential PCR assay. Accordingly, with the genetic diversity already present within the tet(M) sequence of N gonorrhoeae isolates, we should be aware of the sensitivity of the PCR assays in use for tetracycline-resistant N gonorrhoeae detection.
Marquez
Carolina M
CM
Cátedra de Microbiología, Facultad de Química, Montevideo, Uruguay. cmarquez@fq.edu.uy
Dillon
Jo-Anne R
JA
Rodriguez
Veronica
V
Borthagaray
Graciela
G
D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D015257:DNA-Cytosine Methylases; D024881:Drug Resistance, Bacterial; D006069:Gonorrhea / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology; D006801:Humans; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D009344:Neisseria gonorrhoeae / Q000187:drug effects* / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011159:Population Surveillance / Q000379:methods; D013752:Tetracycline / Q000494:pharmacology* / Q000627:therapeutic use; D014583:Uruguay / Q000453:epidemiology
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; C083138:Tet M resistance protein, Bacteria; C029641:DNA modification methylase HpaII; D015257:DNA-Cytosine Methylases; D013752:Tetracycline