title: Evaluation of polymorphisms in pbp4 gene and genetic diversity in penicillin-resistant, ampicillin-susceptible Enterococcus faecalis from hospitals in different states in Brazil.
abstract: The aim of the present study was to verify whether penicillin-resistant, ampicillin-susceptible Enterococcus faecalis (PRASEF) occurred in Brazil prior to the beginning of the 21st century, and to verify whether ampicillin susceptibility can predict susceptibility to other β-lactams in E. faecalis with this inconsistent phenotype. The presence of polymorphisms in the pbp4 gene and genetic diversity among the isolates were investigated. Of 21 PRASEF analyzed, 5 (23.8%) and 4 (19.0%) were imipenem and piperacillin resistant simultaneously by disk diffusion and broth dilution respectively, contradicting the current internationally accepted standards of susceptibility testing. Sequencing of pbp4 gene revealed an amino acid substitution (Asp-573→Glu) in all PRASEF isolates but not in the penicillin-susceptible, ampicillin-susceptible E. faecalis. Most PRASEF (90.5%) had related pulsed-field gel electrophoresis profiles, but were different from other PRASEF described to date. Results demonstrate that penicillin-resistant, ampicillin-susceptible phenotype was already a reality in the 1990s in E. faecalis isolates in different Brazilian states, and some of these isolates were also imipenem- and piperacillin-resistant; therefore, internationally accepted susceptibility criteria cannot be applied to these isolates. According to pbp4 gene sequencing, this study suggests that a specific amino acid substitution in pbp4 gene found in all PRASEF analyzed is associated with penicillin resistance.
authors.affiliation: Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, 14040-903, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Victor Hugo Pacagnelli
authors.initials: VH
authors.lastname: Infante
authors.affiliation: Instituto de Ciências Biológicas e Naturais, Universidade Federal do Triângulo Mineiro, 38015-050, Uberaba, Minas Gerais, Brazil nataliaconceicao5@yahoo.com.br.
authors.forename: Natália
authors.initials: N
authors.lastname: Conceição
authors.affiliation: Instituto de Ciências Biológicas e Naturais, Universidade Federal do Triângulo Mineiro, 38015-050, Uberaba, Minas Gerais, Brazil.
authors.forename: Adriana Gonçalves
authors.initials: AG
authors.lastname: de Oliveira
authors.affiliation: Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, 14040-903, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Ana Lúcia da Costa
authors.initials: AL
authors.lastname: Darini
mesh_terms: D019943:Amino Acid Substitution; D000667:Ampicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000378:metabolism; D001938:Brazil / Q000453:epidemiology; D016521:Electrophoresis, Gel, Pulsed-Field; D013293:Enterococcus faecalis / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D014644:Genetic Variation; D016908:Gram-Positive Bacterial Infections / Q000453:epidemiology / Q000382:microbiology*; D006761:Hospitals; D006801:Humans; D008826:Microbial Sensitivity Tests; D010403:Penicillin Resistance / Q000235:genetics; D046915:Penicillin-Binding Proteins / Q000235:genetics*; D010406:Penicillins / Q000494:pharmacology; D011110:Polymorphism, Genetic; D017422:Sequence Analysis, DNA
chemical_list: D000900:Anti-Bacterial Agents; D046915:Penicillin-Binding Proteins; D010406:Penicillins; D000667:Ampicillin
keywords: Enterococcus faecalis; pbp4 gene; penicillin resistance; penicillin-binding-proteins; pulsed-field gel electrophoresis (PFGE)