In our proposed nomenclature system including GES-type (Guiana-Extended-Spectrum β-lactamase) or IBC-type (Integron-Borne Cephalosporinase) extended-spectrum β-lactamases (ESBLs), GES-2 has an amino acid substitution of G170N, GES-3 has two M62T and E104K substitutions, GES-4 has three M62T, E104K and G170S substitutions, GES-5 has a G170S substitution, GES-6 has two F104K and G170S substitutions, GES-7 (IBC-1) has a G104K substitution, GES-8 (IBC-2) has a A125L substitution and GES-9 has a G243S substitution, compared to the sequence of GES-1. This proposed nomenclature update would not confuse microbiologists studying GES-type ESBLs, fundamentally preventing misleading nomenclature of these antibiotic resistance genes. The definitive renaming of GES/IBC-type ESBLs can help also some researchers to correctly designate new GES-type ESBLs such as novel enzymes identified from some nationwide surveys. In order to detect rapidly and exactly GES-type ESBLs with different hydrolysis profiles and inhibitor-resistance patterns by pyrosequencing, we also proposed here the new four key amino acid substitutions and four GES-type variants as follows: (i) GES-1 able to hydrolyze ceftazidime, (ii) GES-4 able to hydrolyze ceftazidime, cefoxitin and imipenem and able to show inhibitor-resistance, (iii) GES-5 able to hydrolyze ceftazidime, cefoxitin and imipenem and (iv) GES-9 able to hydrolyze ceftazidime and aztreonam.
Jung Hun Lee , Seung Jin Bae , Jae Jin Lee , Il Kwon Bae , Seok Hoon Jeong , Eui Suk Sohn , Yeong Seon Lee and Sang Hee Lee , 2007. Four Exact GES Variants Used for Identification of GES-type Extended-spectrum β-lactamases with Different Hydrolysis Profiles and Inhibitor-Resistance Patterns by Pyrosequencing
. Research Journal of Microbiology, 2: 486-490.