title: Physiological and molecular characteristics of carbapenem resistance in Klebsiella pneumoniae and Enterobacter aerogenes.
abstract: BACKGROUND
  Bacterial resistance is a growing concern in the nosocomial environment in which Klebsiella pneumoniae and Enterobacter aerogenes play an important role due to their opportunism and carbapenemase-production. This work aimed to evaluate physiological and molecular characteristics of carbapenem-resistant K. pneumoniae and E. aerogenes isolated in a Brazilian tertiary hospital.
  
  
  METHODS
  In total, 42 carbapenem-resistant bacteria isolated from clinical specimens were included (21 K. pneumoniae and 21 E. aerogenes). Drug-sensitive K. pneumoniae (n = 27) were also included. Antimicrobial susceptibility and biocide tolerance patterns, hemolytic activity, tolerance to oxidative stress, and aggregative ability were assessed. Genetic markers related to carbapenem resistance, or ESBL-production were screened by PCR.
  
  
  RESULTS
  Compared to drug-sensitive strains, carbapenem-resistant K. pneumoniae were more tolerant to biocides and to oxidative stress, and they displayed an increase in biofilm formation. The genetic markers blaKPC (95.2%) and blaTEM (90.5%) were the most frequent. Among the carbapenem-resistant E. aerogenes strains, blaKPC, and blaTEM were detected in all bacteria. Drug-sensitive E. aerogenes were not isolated in the same period. blaSHV, blaVIM, and blaCTX markers were also observed among carbapenem-resistant bacteria.
  
  
  CONCLUSIONS
  Results suggest that carbapenemase-producing enterobacteria might show peculiar characteristics regarding their physiology associated with their environmental persistency, virulence, and multidrug resistance. The observed phenomenon may have implications not only for antimicrobial chemotherapy, but also for the prognosis of infectious diseases and infection control.
authors.affiliation: Institute of Biological Sciences, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil. ritsanper@gmail.com.
authors.forename: Rito Santo
authors.initials: RS
authors.lastname: Pereira
authors.forename: Vanessa Cordeiro
authors.initials: VC
authors.lastname: Dias
authors.forename: Alessandra Barbosa
authors.initials: AB
authors.lastname: Ferreira-Machado
authors.forename: Juliana Alves
authors.initials: JA
authors.lastname: Resende
authors.forename: André Netto
authors.initials: AN
authors.lastname: Bastos
authors.forename: Lucas Quinet
authors.initials: LQ
authors.lastname: Andrade Bastos
authors.forename: Victor Quinet
authors.initials: VQ
authors.lastname: Andrade Bastos
authors.forename: Ricardo Villela
authors.initials: RV
authors.lastname: Bastos
authors.forename: Vânia Lúcia
authors.initials: VL
authors.lastname: Da Silva
authors.forename: Cláudio Galuppo
authors.initials: CG
authors.lastname: Diniz
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018441:Biofilms / Q000254:growth & development; D001938:Brazil; D015780:Carbapenems / Q000494:pharmacology*; D003430:Cross-Sectional Studies; D004202:Disinfectants / Q000494:pharmacology; D021902:Enterobacter aerogenes / Q000187:drug effects* / Q000235:genetics* / Q000502:physiology; D004756:Enterobacteriaceae Infections / Q000382:microbiology; D005260:Female; D006801:Humans; D007711:Klebsiella pneumoniae / Q000187:drug effects* / Q000235:genetics* / Q000502:physiology; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress; D016133:Polymerase Chain Reaction; D013312:Stress, Physiological; D062606:Tertiary Care Centers; D055815:Young Adult; D018440:beta-Lactam Resistance
chemical_list: D000900:Anti-Bacterial Agents; D015780:Carbapenems; D004202:Disinfectants