title: Role of beta-lactamase inhibitors in enterobacterial isolates producing extended-spectrum beta-lactamases.
abstract: OBJECTIVE
  To determine the in vitro activity of beta-lactamase inhibitors (clavulanic acid and sulbactam) in combination with third-generation cephalosporins and monobactam against extended-spectrum beta-lactamase (ESBL)-producing members of the Enterobacteriaceae family.
  
  
  METHODS
  A total of 361 ESBL-producing enterobacterial isolates obtained from patients of a university hospital were screened for the status of co-production of AmpC beta-lactamase. These strains were further subjected to an MIC study using third-generation cephalosporins and monobactam, and reductions were observed after combining with beta-lactamase inhibitors at a fixed concentration of 4 mg/L.
  
  
  RESULTS
  Most of the isolates showed 8-fold reduction with sulbactam when combined with ceftriaxone, cefpodoxime and cefotaxime but not with ceftazidime and aztreonam, whereas clavulanic acid showed the same result with all the cephalosporins tested. Further, both the inhibitors showed greater reduced MIC when combined with aztreonam.
  
  
  CONCLUSIONS
  As the ability of clavulanic acid to induce AmpC production may interfere with ESBL detection, sulbactam is likely to be preferred over clavulanic acid after standardization of an appropriate concentration for ESBL detection in the scenario of increased prevalence of AmpC producers. Greater in vitro activity of these inhibitors when combined with aztreonam further indicates the need of studies to evaluate these combination antimicrobials in clinical settings as they can play a significant role for clinicians as viable alternatives to treat infections caused by such organisms.
authors.affiliation: Department of Microbiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi 221005, India.
authors.forename: Amitabha
authors.initials: A
authors.lastname: Bhattacharjee
authors.forename: Malay Ranjan
authors.initials: MR
authors.lastname: Sen
authors.forename: Pradyot
authors.initials: P
authors.lastname: Prakash
authors.forename: Shampa
authors.initials: S
authors.lastname: Anupurba
mesh_terms: D024881:Drug Resistance, Bacterial / Q000187:drug effects / Q000502:physiology; D004755:Enterobacteriaceae / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases / Q000096:biosynthesis / Q000235:genetics
chemical_list: D004791:Enzyme Inhibitors; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases