Gram-negative sepsis: Laboratory Identification

Extended Spectrum Beta Lactamases

  • In follow-up to the observations of the ESBL screening test, the following antibiotic susceptibility profile was later reported:
  • Ampicillin = R; Cefazolin = R; Cefoxitin 1 = S; Ciprofloxacin 0.25 = S; Gentamicin 1 = S; Ceftazidime 32 = R; Imipenem <0.25 = S; Piperacillin = R; Trimeth/Sulfa <1/20 = S
  • The susceptibility of the 2nd generation drug cefoxitin, with resistance of the 1st generation cefazolin and the 3rd generation ceftazidime, is another way in addition to the screening test in which ESBL activity may be detected.
  • It is recommended that clinical microbiologists check the antibiotic susceptibility profiles for possible ESBL activity of clinically significant isolates of K. pneumoniae and E. coli.
  • Most automated systems have built in methods for automatically detecting an ESBL isolate, or provide an "alert" that such a strain may be present.

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