title: Evaluation of Escherichia coli viability by flow cytometry: A method for determining bacterial responses to antibiotic exposure.
abstract: BACKGROUND
  In this study, we check for the presence of specific resistance genes by polymerase chain reaction (PCR) and then we used flow cytometry (FCM) to evaluate antibiotic-induced effects in different strains of Escherichia coli (E. coli).
  
  
  METHODS
  The presence of resistance genes was investigated by PCR in 10 strains of E. coli isolated from Foglia River. Bacterial responses to different antibiotics were also tested with FCM techniques by evaluating both the degree of decrease in viability and the light scatter changes in all of the strains.
  
  
  RESULTS
  PCR revealed that only one strain exhibits the presence of one resistance gene. Despite this, analyses of strains using FCM evidenced the presence of viable subpopulations after antibiotic treatment. Furthermore, analyses of scatter signals revealed profound changes in the Forward Scatter and Side Scatter of the bacterial populations as a consequence of antibiotic exposure, confirming the viability and membrane potential data. The riverine strains were in general less sensitive to antibiotics than the reference strain (ATCC 25922).
  
  
  CONCLUSIONS
  Antibiotic resistance is a widespread phenomena. The multiparametric approach based on FCM used in this study, providing results about different aspects (cell viability, membrane potential, light scatter changes), may overcome the limitation of PCR and could represent an adequate method for the evaluation of bacteria responses to antibiotic exposure.
authors.affiliation: Department of Earth, Life and Environmental Sciences, University of Urbino "Carlo Bo", 61029, Urbino, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Boi
authors.forename: Anita
authors.initials: A
authors.lastname: Manti
authors.forename: Anna
authors.initials: A
authors.lastname: Pianetti
authors.forename: Luigia
authors.initials: L
authors.lastname: Sabatini
authors.forename: Davide
authors.initials: D
authors.lastname: Sisti
authors.forename: Marco Bruno
authors.initials: MB
authors.lastname: Rocchi
authors.forename: Francesca
authors.initials: F
authors.lastname: Bruscolini
authors.forename: Luca
authors.initials: L
authors.lastname: Galluzzi
authors.forename: Stefano
authors.initials: S
authors.lastname: Papa
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002232:Carbocyanines; D002462:Cell Membrane / Q000187:drug effects; D024901:Drug Resistance, Multiple, Bacterial; D004926:Escherichia coli / Q000145:classification / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D005434:Flow Cytometry; D005456:Fluorescent Dyes; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects; D016133:Polymerase Chain Reaction; D045483:Rivers / Q000382:microbiology; D014871:Water Microbiology
chemical_list: D000900:Anti-Bacterial Agents; D002232:Carbocyanines; D005456:Fluorescent Dyes; C081554:3,3'-diethyloxacarbocyanine
keywords: Escherichia coli; antibiotic effects; flow cytometry