Characterization of an outbreak of tetM-containing Neisseria gonorrhoeae in Argentina.

Phenotypic and molecular characterization of an outbreak of 9 Neisseria gonorrhoeae (NG) isolates exhibiting high-level plasmid mediated resistance to penicillin and tetracycline (PP-TRNG) that took place in Tandil, Argentina between February and April 1995. Comparison with the patterns of the 3 PP-TRNG strains previously isolated were made. We determined the following markers for each strain: antimicrobial susceptibility, serogroup, auxotype, plasmid profile, presence of tetM determinant and restriction pattern of the tetM-containing plasmid. Antimicrobial tests values were: tetracycline disk diameter 12-14 mm, minimum inhibitory concentration (MIC) 32 micrograms/ml; penicillin disk diameter 6 mm, MIC 32 micrograms/ml and sensitive by both methods to spectinomycin, cefuroxime, ceftriaxone and ciprofloxacin. All isolates were of the same serogroup (WI). Ten of the strains, including the 9 from Tandil outbreak, were arginine-requiring, while the other 2 were methionine and arginine-requiring. All of them demonstrate the same plasmid profile (2.6, 3.2, 25.2 MDa). They were positive for the tetM determinant and the restriction analysis identified it is a Dutch-type plasmid. In spite of the temporal and geographical dispersion, PP-TRNG strains in Argentina seem to be highly homogeneous in terms of antimicrobial susceptibility, serogroup, plasmid profiles and even auxotype.