Neisseria gonorrhoeae is the etiological agent of the sexually transmitted infection gonorrhea, which remains a major public health issue. It represents 88 million of the estimated 448 million new cases of curable sexually transmitted infections that occur globally every year [
1]. Over time,
N. gonorrhoeae has progressively developed resistance to a wide range of antibiotics, including penicillin, ciprofloxacin, tetracyclines, macrolides, and more recently to third-generation cephalosporins [
2,
3]. Antimicrobial resistance in
N. gonorrhoeae became apparent shortly after the introduction of antibiotics into clinical practice. Moreover, its ability to acquire and/or maintain antibiotic resistance genes has become a considerable problem and an obstacle to successful therapeutic treatment [
4,
5]. In 1943, penicillin was introduced as the first-line treatment of gonorrhea, but it was abandoned due to the emergence of chromosomally mediated penicillin resistance and PPNG isolates [
6,
7]. PPNG strains were reported for the first time in 1976 in the United Kingdom and the United States [
8,
9]. These strains produce a TEM type β-lactamase, which is carried on several related plasmids. To date, eight plasmid types have been described and named according to their epidemiological origin. Strains harbouring Asian, African and Toronto/Rio plasmids have been reported throughout the world [
10,
11]. Other plasmid variants have been described, including Nimes, New Zealand, Johannesburg, and Australian plasmids [
12‐
15]. The PPNG isolate in Argentina was reported in the 1980’s and has spread since then [
16]. PPNG isolates are highly prevalent in our country and three plasmids types (Asian, African and Toronto/Rio plasmids) have been detected, resulting African and Toronto/Rio the most prevalent.
The first PPNG strains produced a TEM-1 β-lactamase, a class A enzyme encoded by
bla
TEM-1 allele [
17]. TEM-1 β-lactamase efficiently hydrolyzes penicillins and many cephalosporins, but it is not an effective catalyst for extended spectrum cephalosporin turnover. For around thirty years, other β-lactamases were not described in gonococci. However, a PPNG isolate carrying a
bla
TEM-135 gene was reported from Thailand in the year 2009 [
18]. TEM-135 was first described in 2005 in a
Salmonella enterica subsp.
enterica serovar Typhimurium isolate and differs from TEM-1 by one single nucleotide substitution at position 539 (T → C), resulting in a single amino acid substitution, M182T [
19]. Prevalence studies from different countries revealed that PPNG isolates possessing Asian, Toronto/Rio, African and Australian plasmids carried
bla
TEM-135 gene [
20‐
23]. Recently PPNG isolates carrying Toronto/Rio plasmid from Argentina that possessed the novel
bla
TEM-220 allele were identified [
24]. TEM-220 differs from TEM-135 by one nucleotide substitution at position 547 (G → A), resulting in the amino acid substitution A185T. The prevalence and characteristics of TEM-220 strains worldwide are unknown and it seems imperative to study them.
Prevalence of PPNG isolates in Argentina has been reported previously, but national data of PPNG isolates possessing bla
TEM-220 is lacking. The objective of our study was to detect bla
TEM-220 gene in PPNG isolates possessing Toronto/Rio plasmid recovered between 2002 and 2011 in Argentina, and to evaluate the proportion of isolates producing non-TEM-220 containing the T539C substitution in the bla
TEM allele.