Prevalence of bla(TEM-220) gene in Penicillinase-producing Neisseria gonorrhoeae strains carrying Toronto/Rio plasmid in Argentina, 2002 – 2011

BACKGROUND: Penicillinase-producing Neisseria gonorroheae (PPNG) was first isolated in 1976. PPNG strains carrying bla(TEM-1) and bla(TEM-135) gene have been described in different countries. Recently, a novel bla(TEM-220) allele was detected in PPNG isolates carrying Toronto/Rio plasmid. The prevalence and characteristics of TEM-220 strains worldwide are unknown, and therefore, it needs to be studied. The purpose of this study was to detect bla(TEM-220) gene in PPNG strains possessing Toronto/Rio plasmid over a period of ten years in Argentina, and to evaluate the proportion of isolates producing non-TEM-220 containing the T539C substitution in the bla(TEM) allele. METHODS: One hundred and fifty one PPNG isolates carrying Toronto/Rio plasmid were studied between 2002 and 2011. A mismatch amplification mutation assay (MAMA) PCR was used to identify the T539C substitution in the bla(TEM) allele and a MAMA-PCR protocol was developed to detect the G547A substitution in the bla(TEM-220). The reference agar dilution method of the Clinical and Laboratory Standard Institute (CLSI) was used for susceptibility testing to five β-lactams antibiotics, ciprofloxacin, tetracycline and azithromycin. In all TEM-220-producing isolates, the whole bla(TEM) gene was sequenced and the isolates were typed using N. gonorroheae multiantigen sequence typing (NG-MAST). RESULTS: MAMA PCR successfully identified the G547A substitution in the bla(TEM-220) allele. The proportion of isolates that possessed the bla(TEM-220) allele was 2.6 %, and 93.2 % MAMA TEM-220 PCR-negative isolates showed the T539C substitution in the bla(TEM) gene. No differences in the susceptibility to five beta-lactam antibiotics tested were observed in PPNG isolates TEM-220-producing and PPNG isolates carrying the T539C substitution in the bla(TEM) gene. All TEM-220 isolates were indistinguishable by NG-MAST. CONCLUSION: This is the first study which shows the prevalence of bla(TEM-220) in N. gonorrhoeae isolates carrying Toronto/Rio plasmid in Argentina. Although the bla(TEM-220) allele does not appear to be associated with an extended spectrum beta-lactamase (ESBL) phenotype of resistance, a single nucleotide polymorphism added to the bla(TEM-220) or bla(TEM) containing the T539C substitution could lead to the emergence of ESBL. Thus, it is imperative to investigate in surveillance programs, not only the plasmid type in PPNG isolates and the bla(TEM) allele associated, but phenotypical characteristics and geographical distribution of isolates.