title: Molecular analysis of porin gene transcription in heterogenotypic multidrug-resistant Escherichia coli isolates from scouring calves.
abstract: BACKGROUND
  Despite evidence that altered membrane porins may impair microbial drug uptake thereby potentially compounding efflux pump-mediated multidrug resistance, few studies have evaluated gene transcription to identify multidrug-resistance-associated porins and other potential drug targets.
  
  
  METHODS
  Genes that encode six membrane porins (fadL, lamB, ompC, ompF, ompW and yiaT) and two membrane proteins (tolC and ompT) were assessed by PCR and by quantitative real-time PCR (qRT-PCR) analysis of 10 multidrug-resistant (MDR) and 10 antibiotic-susceptible (AS) Escherichia coli isolates. The mean DeltaDeltaCt values for the study E. coli genes were analysed by the Wilcoxon test (P = 0.05).
  
  
  RESULTS
  All 20 E. coli isolates tested positive for tolC, lamB, ompC, ompF genes, while 10 MDR and 9/10 (90%) AS isolates were positive for the fadL gene. Seven out of 10 (70%) MDR and 7/10 (70%) AS isolates were positive for the yiaT gene, while 7/10 (70%) MDR and only 4/10 (40%) AS isolates were positive for the ompT gene. The mean DeltaDeltaCt values for the tolC and yiaT genes were significantly higher in MDR than in AS isolates (Wilcoxon test; P < 0.05). No significant difference was seen with respect to fadL, lamB, ompC, ompF, ompT and ompW gene transcription (Wilcoxon test; P > 0.05).
  
  
  CONCLUSIONS
  Findings suggest up-regulated transcription of tolC and yiaT genes in the MDR E. coli isolates. These results indirectly suggest that TolC and YiaT proteins may play some role(s) in multidrug resistance, but proteomic studies are needed before the two proteins are considered potential drug targets.
authors.affiliation: Department of Veterinary and Microbiological Sciences, North Dakota State University, 1523 Centennial Blvd, Fargo, ND 58108, USA.
authors.forename: Heather M
authors.initials: HM
authors.lastname: Vinson
authors.forename: Ablesh
authors.initials: A
authors.lastname: Gautam
authors.forename: Susan
authors.initials: S
authors.lastname: Olet
authors.forename: Penelope S
authors.initials: PS
authors.lastname: Gibbs
authors.forename: Robert
authors.initials: R
authors.lastname: Barigye
mesh_terms: D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology*; D024901:Drug Resistance, Multiple, Bacterial; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D004927:Escherichia coli Infections / Q000382:microbiology / Q000662:veterinary*; D029968:Escherichia coli Proteins / Q000096:biosynthesis*; D020869:Gene Expression Profiling; D016133:Polymerase Chain Reaction; D018272:Porins / Q000096:biosynthesis*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic
chemical_list: D029968:Escherichia coli Proteins; D018272:Porins