title: Cefoxitin resistance mediated by loss of a porin in clinical strains of Klebsiella pneumoniae and Escherichia coli.
abstract: OBJECTIVE
  Porins are outer membrane protein (OMP) that form water filled channels that permit the diffusion of small hydrophilic solutes like beta-lactam antibiotics across the outer membrane. Two major porins that facilitate diffusion of antimicrobials have been described in Klebsiella spp. and Escherichia coli. The present study was carried out to examine the role of porins among Extended Spectrum beta-Lactamase (ESBL) and AmpC beta-Lactamase positive strains of Klebsiella spp. and E.coli.
  
  
  METHODS
  Preparation of OMP from phenotypically characterized clinical isolates K.pneumoniae and E.coli and the separation of the proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis were performed as per a previously described procedure.
  
  
  RESULTS
  OMP analysis revealed that cefoxitin and ceftazidime resistance was mediated by loss of a porin Omp K35 in the isolates of K.pneumoniae and E.coli.
  
  
  CONCLUSIONS
  Loss of porin mediated resistance mechanism against cefoxitin was observed among the multidrug resistant K.pneumoniae and E.coli.
authors.affiliation: Department of Microbiology, Dr. ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani, Chennai 600 113, India. sowanand@hotmail.com
authors.forename: S
authors.initials: S
authors.lastname: Ananthan
authors.forename: A
authors.initials: A
authors.lastname: Subha
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002440:Cefoxitin / Q000494:pharmacology*; D002675:Child, Preschool; D018432:Drug Resistance, Multiple; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007223:Infant; D007709:Klebsiella / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D018272:Porins / Q000172:deficiency* / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D018272:Porins; D002440:Cefoxitin