title: Morphological, biochemical, physiological and molecular aspects of the response of Fusobacterium nucleatum exposed to subinhibitory concentrations of antimicrobials.
abstract: Subinhibitory concentrations (SICs) of antimicrobials may result in alterations in bacterial biology with implications for its potential aggression. This has considerable importance for the resident microbiota. Our aim was to analyze the effects of SICs of antimicrobials on the morphological, biochemical, physiological and molecular characteristics of the resident anaerobic Fusobacterium nucleatum. Fourteen strains were obtained from F. nucleatum ATCC 25586, selected by culturing on SICs of ampicillin, ampicillin/sulbactam, clindamycin, chloramphenicol, levofloxacin, metronidazole and piperacillin/tazobactam and subsequent culturing in the absence of drugs. Antimicrobial susceptibility, bacterial morphology, biochemical profiles and biofilm formation were evaluated. Genotyping and analysis of protein profiles were also performed. The antimicrobial susceptibility patterns showed that most of the derived strains were less sensitive to the antimicrobials, even after culturing them without drugs. Morphological and cell complexity alterations were observed, mainly in strains grown in SICs of β-lactam; these strains also expressed a reduced ability for biofilm formation. The other strains showed an increase in biofilm formation but no apparent morphological changes. Alterations were observed in the carbohydrate metabolism patterns and in the activity of microbial enzymes. Several proteins were positively or negatively regulated and there was polymorphism in the DNA from all derived strains. Therefore, SICs of antimicrobials induce alterations in F. nucleatum, which directly impact its biology. These results emphasize the risk of inadequate antibioticotherapy, which may have serious implications for clinical microbiology and infectious diseases and also may interfere with the host-bacteria relationship.
authors.affiliation: Department of Parasitology, Microbiology and Immunology, Institute of Biological Sciences, Federal University of Juiz de Fora, 36036-900 Juiz de Fora, Minas Gerais, Brazil. jasflink@yahoo.com
authors.forename: Job Alves
authors.initials: JA
authors.lastname: de Souza Filho
authors.forename: Cláudio Galuppo
authors.initials: CG
authors.lastname: Diniz
authors.forename: Natália Bento
authors.initials: NB
authors.lastname: Barbosa
authors.forename: Michele Cristine Ribeiro
authors.initials: MC
authors.lastname: de Freitas
authors.forename: Mariana Silva
authors.initials: MS
authors.lastname: Lopes Neves
authors.forename: Rafaella Nogueira
authors.initials: RN
authors.lastname: da Gama Mazzei
authors.forename: Jacy
authors.initials: J
authors.lastname: Gameiro
authors.forename: Cíntia Marques
authors.initials: CM
authors.lastname: Coelho
authors.forename: Vânia Lúcia
authors.initials: VL
authors.lastname: da Silva
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000032:analysis; D015373:Bacterial Typing Techniques; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development; D050260:Carbohydrate Metabolism / Q000187:drug effects; D004798:Enzymes / Q000378:metabolism; D016967:Fusobacterium nucleatum / Q000166:cytology / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D005838:Genotype; D008826:Microbial Sensitivity Tests; D011110:Polymorphism, Genetic; D020543:Proteome / Q000032:analysis
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004798:Enzymes; D020543:Proteome