title: The influence of biofilm formation and multidrug resistance on environmental survival of clinical and environmental isolates of Acinetobacter baumannii.
abstract: Acinetobacter baumannii is a gram-negative, opportunistic pathogen. Its ability to form biofilm and increasing resistance to antibiotic agents present challenges for infection control. A better understanding of the influence of biofilm formation and antibiotic resistance on environmental persistence of A baumannii in hospital settings is needed for more effective infection control.
  
  
  
  A baumannii strains isolated from patients and the hospital environment were identified via Matrix Assisted Laser Desorption Ionization Time-of-Flight (MALDI-TOF) mass spectrometry (Bruker Daltonics, Bellerica, MA), repetitive extragenic palindromic polymerase chain reaction genotyped, and antibiotic resistance was determined using Vitek 2 (bioMérieux, Inc, Durham NC). Biofilm mass was quantified via microtiter plate method and desiccation tolerance determined up to 56 days.
  
  
  
  High biofilm forming, clinical, multidrug-resistant- (MDR) positive strains were 50% less likely to die of desiccation than low biofilm, non-MDR strains. In contrast, environmental, MDR-positive, low biofilm forming strains had a 2.7 times increase in risk of cell death due to desiccation compared with their MDR-negative counterparts. MDR-negative, high biofilm forming environmental strains had a 60% decrease in risk compared with their low biofilm forming counterparts.
  
  
  
  The MDR-positive phenotype was deleterious for environmental strains and the high biofilm phenotype was critical for survival. This study provides evidence of the trade-off between antibiotic resistance and desiccation tolerance, driven by condition-dependent adaptation, and establishes rationale for research into the genetic basis of the variation in fitness cost between clinical and environmental isolates.
authors: Department of Environmental Health and Science, University of Michigan, Ann Arbor, MI.
authors: Christine
authors: C
authors: Greene
authors: Department of Environmental Health and Science, University of Michigan, Ann Arbor, MI.
authors: Gayathri
authors: G
authors: Vadlamudi
authors: Department of Epidemiology, University of Michigan, Ann Arbor, MI; Department of Pathology, University of Michigan, Ann Arbor, MI.
authors: Duane
authors: D
authors: Newton
authors: Department of Epidemiology, University of Michigan, Ann Arbor, MI.
authors: Betsy
authors: B
authors: Foxman
authors: Department of Environmental Health and Science, University of Michigan, Ann Arbor, MI. Electronic address: cxi@umich.edu.
authors: Chuanwu
authors: C
authors: Xi
mesh_terms: D000151:Acinetobacter Infections / Q000382:microbiology*; D040981:Acinetobacter baumannii / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D000328:Adult; D001431:Bacteriological Techniques; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development*; D024901:Drug Resistance, Multiple, Bacterial; D004783:Environmental Microbiology; D005260:Female; D060005:Genotyping Techniques; D006801:Humans; D008297:Male; D050296:Microbial Viability; D008875:Middle Aged; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
keywords: Condition-dependent adaptation; Desiccation tolerance; Environmental transmission; Fitness cost; Hospital; Infection control