title: Carbapenem-resistant and cephalosporin-susceptible: a worrisome phenotype among Pseudomonas aeruginosa clinical isolates in Brazil.
abstract: The mechanisms involved in the uncommon resistance phenotype, carbapenem resistance and broad-spectrum cephalosporin susceptibility, were investigated in 25 Pseudomonas aeruginosa clinical isolates that exhibited this phenotype, which were recovered from three different hospitals located in São Paulo, Brazil. The antimicrobial susceptibility profile was determined by CLSI broth microdilution. β-lactamase-encoding genes were investigated by PCR followed by DNA sequencing. Carbapenem hydrolysis activity was investigated by spectrophotometer and MALDI-TOF assays. The mRNA transcription level of oprD was assessed by qRT-PCR and the outer membrane proteins profile was evaluated by SDS-PAGE. Genetic relationship among P. aeruginosa isolates was assessed by PFGE. Carbapenems hydrolysis was not detected by carbapenemase assay in the carbapenem-resistant and cephalosporin-susceptible P. aueruginosa clinical isolates. OprD decreased expression was observed in all P. aeruginosa isolates by qRT-PCR. The outer membrane protein profile by SDS-PAGE suggested a change in the expression of the 46kDa porin that could correspond to OprD porin. The isolates were clustered into 17 genotypes without predominance of a specific PFGE pattern. These results emphasize the involvement of multiple chromosomal mechanisms in carbapenem-resistance among clinical isolates of P. aeruginosa, alert for adaptation of P. aeruginosa clinical isolates under antimicrobial selective pressure and make aware of the emergence of an uncommon phenotype among P. aeruginosa clinical isolates.
authors.affiliation: Universidade Federal de São Paulo, Laboratório ALERTA, Disciplina de Infectologia, São Paulo, SP, Brazil. Electronic address: elocampana@gmail.com.
authors.forename: Eloiza Helena
authors.initials: EH
authors.lastname: Campana
authors.affiliation: Universidade Federal de São Paulo, Laboratório ALERTA, Disciplina de Infectologia, São Paulo, SP, Brazil.
authors.forename: Danilo Elias
authors.initials: DE
authors.lastname: Xavier
authors.affiliation: Universidade Federal de São Paulo, Laboratório ALERTA, Disciplina de Infectologia, São Paulo, SP, Brazil.
authors.forename: Fernanda Villas-Boas
authors.initials: FV
authors.lastname: Petrolini
authors.affiliation: Universidade Federal de São Paulo, Laboratório ALERTA, Disciplina de Infectologia, São Paulo, SP, Brazil.
authors.forename: Jhonatha Rodrigo
authors.initials: JR
authors.lastname: Cordeiro-Moura
authors.affiliation: Hospital Benemérita Sociedade Portuguesa de Beneficência e Hospital do Coração, São Paulo, SP, Brazil.
authors.forename: Maria Rita Elmor de
authors.initials: MR
authors.lastname: Araujo
authors.affiliation: Universidade Federal de São Paulo, Laboratório ALERTA, Disciplina de Infectologia, São Paulo, SP, Brazil.
authors.forename: Ana Cristina
authors.initials: AC
authors.lastname: Gales
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins / Q000378:metabolism; D001938:Brazil; D015780:Carbapenems / Q000494:pharmacology*; D002511:Cephalosporins / Q000494:pharmacology*; D004269:DNA, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D006801:Humans; D008826:Microbial Sensitivity Tests; D010641:Phenotype; D018272:Porins / Q000378:metabolism; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D013056:Spectrophotometry, Ultraviolet; D018440:beta-Lactam Resistance / Q000235:genetics; D001618:beta-Lactamases / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D015780:Carbapenems; D002511:Cephalosporins; D004269:DNA, Bacterial; D018272:Porins; C077157:OprD protein, Pseudomonas aeruginosa; D001618:beta-Lactamases; C063912:carbapenemase
keywords: Carbapenem resistance; Gram-negative bacilli; OprD porin