title: Comparative antimicrobial susceptibility of biofilm versus planktonic forms of Salmonella enterica strains isolated from children with gastroenteritis.
abstract: In the present study, 194 Salmonella enterica strains, isolated from infected children and belonging to various serotypes, were investigated for their ability to form biofilms and the biofilm forms of the isolated strains were compared to their corresponding planktonic forms with respect to the antimicrobial susceptibility. For the biofilm-forming strains, the minimum inhibitory concentration for bacterial regrowth (MICBR) from the biofilm of nine clinically applicable antimicrobial agents was determined, and the results were compared to the respective MIC values of the planktonic forms. One hundred and nine S. enterica strains out of 194 (56%) belonging to 13 serotypes were biofilm-forming. The biofilm forms showed increased antimicrobial resistance compared to the planktonic bacteria. The highest resistance rates of the biofilm bacteria were observed with respect to gentamicin (89.9%) and ampicillin (84.4%), and the lowest rates with respect to ciprofloxacin and moxifloxacin (2.8% for both). A remarkable shift of the MICBR(50) and MICBR(90) toward resistance was observed in the biofilm forms as compared to the respective planktonic forms. The development of new consensus methods for the determination of the antimicrobial susceptibility of biofilm forms seems to be a major research challenge. Further studies are required in order to elucidate the biofilm antimicrobial resistance mechanisms of the bacterial biofilms and their contribution to therapeutic failure in infections with in vitro susceptible bacteria.
authors.affiliation: Department of Clinical Microbiology, Penteli Children's Hospital, Athens, Greece.
authors.forename: K
authors.initials: K
authors.lastname: Papavasileiou
authors.forename: E
authors.initials: E
authors.lastname: Papavasileiou
authors.forename: A
authors.initials: A
authors.lastname: Tseleni-Kotsovili
authors.forename: S
authors.initials: S
authors.lastname: Bersimis
authors.forename: C
authors.initials: C
authors.lastname: Nicolaou
authors.forename: A
authors.initials: A
authors.lastname: Ioannidis
authors.forename: S
authors.initials: S
authors.lastname: Chatzipanagiotou
mesh_terms: D000293:Adolescent; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects*; D002648:Child; D002675:Child, Preschool; D024881:Drug Resistance, Bacterial; D005759:Gastroenteritis / Q000382:microbiology*; D006801:Humans; D007223:Infant; D008826:Microbial Sensitivity Tests; D010933:Plankton / Q000187:drug effects; D012480:Salmonella Infections / Q000382:microbiology*; D019779:Salmonella enterica / Q000187:drug effects* / Q000302:isolation & purification; D012477:Salmonella enteritidis / Q000187:drug effects / Q000302:isolation & purification; D012486:Salmonella typhimurium / Q000187:drug effects / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents