| Autor: |
Streling AP; Laboratório ALERTA, Division of Infectious Diseases, Department of Internal Medicine, Escola Paulista de Medicina (EPM), Universidade Federal de São Paulo (UNIFESP), São Paulo, São Paulo, Brazil., Cayô R; Laboratório ALERTA, Division of Infectious Diseases, Department of Internal Medicine, Escola Paulista de Medicina (EPM), Universidade Federal de São Paulo (UNIFESP), São Paulo, São Paulo, Brazil.; Laboratório de Imunologia e Microbiologia (LIB), Setor de Biologia Molecular, Microbiologia e Imunologia, Departamento de Ciências Biológicas (DCB), Instituto de Ciências Ambientais, Químicas e Farmacêuticas (ICAQF), Universidade Federal de São Paulo (UNIFESP), Diadema, São Paulo, Brazil., Nodari CS; Laboratório ALERTA, Division of Infectious Diseases, Department of Internal Medicine, Escola Paulista de Medicina (EPM), Universidade Federal de São Paulo (UNIFESP), São Paulo, São Paulo, Brazil., Almeida LGP; National Laboratory for Scientific Computing (LNCC), Petrópolis, Rio de Janeiro, Brazil., Bronze F; Laboratório de Enzimologia, Department of Biophysics, Escola Paulista de Medicina (EPM), Universidade Federal de São Paulo (UNIFESP), São Paulo, São Paulo, Brazil., Siqueira AV; Laboratório ALERTA, Division of Infectious Diseases, Department of Internal Medicine, Escola Paulista de Medicina (EPM), Universidade Federal de São Paulo (UNIFESP), São Paulo, São Paulo, Brazil., Matos AP; Laboratório ALERTA, Division of Infectious Diseases, Department of Internal Medicine, Escola Paulista de Medicina (EPM), Universidade Federal de São Paulo (UNIFESP), São Paulo, São Paulo, Brazil., Oliveira V; Laboratório de Enzimologia, Department of Biophysics, Escola Paulista de Medicina (EPM), Universidade Federal de São Paulo (UNIFESP), São Paulo, São Paulo, Brazil., Vasconcelos ATR; National Laboratory for Scientific Computing (LNCC), Petrópolis, Rio de Janeiro, Brazil., Marcondes MFM; Laboratório de Enzimologia, Department of Biophysics, Escola Paulista de Medicina (EPM), Universidade Federal de São Paulo (UNIFESP), São Paulo, São Paulo, Brazil., Gales AC; Laboratório ALERTA, Division of Infectious Diseases, Department of Internal Medicine, Escola Paulista de Medicina (EPM), Universidade Federal de São Paulo (UNIFESP), São Paulo, São Paulo, Brazil. |
| Abstrakt: |
Pseudomonas aeruginosa is an opportunist pathogen usually associated with life threatening infections and exhibits a set of intrinsic and acquired antimicrobial mechanisms. Although resistance to penicillins-like compounds is commonly associated with the chromosomal Pseudomonas -derived cephalosporinases β-lactamase, the real contribution of OXA-50, a second chromosomally encoded β-lactamase, remains unclear. In this study, we characterized the biochemical properties of OXA-50, OXA-488, and OXA-494. Both oxacilinases differ from OXA-50 in two amino acids each. The bla OXA-50 , bla OXA-488 , and bla OXA-494 were cloned into pET26b + that was transformed into Escherichia coli DH5α strain, expressed in E. coli BL21 strain, and then purified for obtaining the hydrolytic parameters. Benzylpenicillin was the preferential substrate instead of oxacillin. Besides, OXA-488 showed a threefold increase in catalytic efficiency for benzylpenicillin, and it was twofold more efficient in hydrolyzing imipenem, compared with OXA-50, although such carbapenemase activity was considered weak. In addition, OXA-488 and OXA-494 showed an increased affinity for penicillins, which contributed to the increased catalytic efficiency against ampicillin, especially OXA-488. Chromosomally encoded resistance mechanisms are usually overshadowed by acquired mechanisms. However, understanding their real contribution is essential to comprehend the versatile profiles verified in P. aeruginosa isolates. Such information can help to choose the best therapy in a scenario of limited options. |
