Clinical and microbiologic analysis of a hospital's extended-spectrum beta-lactamase-producing isolates over a 2-year period.
OBJECTIVE
To evaluate the microbiologic and clinical outcomes of patients with extended-spectrum beta-lactamase (ESBL)-producing isolates over a 2-year period.


METHODS
Retrospective analysis.


METHODS
Tertiary care teaching hospital.


METHODS
Twenty-one patients with cultures of confirmed ESBL-producing Escherichia coli, Klebsiella pneumoniae, or Klebsiella oxytoca.


RESULTS
Antimicrobial susceptibilities of piperacillin-tazobactam, cefotetan, carbapenems, aminoglycosides, fluoroquinolones, trimethoprim-sulfamethoxazole, and nitrofurantoin (nitrofurantoin for urinary isolates only) of confirmed ESBL producers at our institution were determined, as well as clinical outcomes of patients with ESBL-producing isolates. Microbiologic and medical records were reviewed for patient sex and age, antimicrobial susceptibilities, antimicrobial therapy, and clinical and microbiologic outcomes. From January 2000-December 2001, 31 isolates were confirmed as ESBL producers (6 E. coli, 11 K. pneumoniae, and 14 K. oxytoca). A statistically significant increase occurred over the 2-year period from 9 (0.6%) of 1414 isolates in 2000 to 22 (1.8%) of 1218 isolates in 2001 (p = 0.0055). All isolates were susceptible to carbapenems, and more than 88% were susceptible to amikacin, cefotetan, or nitrofurantoin. Less than 70% of isolates were susceptible to gentamicin, fluoroquinolones, piperacillin-tazobactam, or trimethoprim-sulfamethoxazole. All patients treated with a carbapenem experienced clinical cure. Piperacillin-tazobactam alone and in combination resulted in an overall clinical cure rate of 55%, with a 50% cure rate for isolates susceptible to piperacillin-tazobactam. All patients in whom antibiotic therapy failed had been treated with piperacillin-tazobactam or cefepime, either alone or in combination with a fluoroquinolone.


CONCLUSIONS
Carbapenems remain the treatment of choice for ESBL-producing pathogens. Piperacillin-tazobactam and cefepime should not be routinely administered for the treatment of these organisms.
College of Pharmacy, University of Texas at Austin, USA. burgessd@uthscsa.edu
David S
DS
Burgess
Ronald G
RG
Hall
James S
JS
Lewis
James H
JH
Jorgensen
Jan E
JE
Patterson
D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use; D003428:Cross Infection / Q000188:drug therapy / Q000382:microbiology; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000382:microbiology*; D006746:Hospital Bed Capacity, 500 and over; D006785:Hospitals, University; D006801:Humans; D007709:Klebsiella / Q000187:drug effects / Q000201:enzymology / Q000302:isolation & purification; D007710:Klebsiella Infections / Q000188:drug therapy / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D012189:Retrospective Studies; D018440:beta-Lactam Resistance; D001618:beta-Lactamases / Q000032:analysis / Q000096:biosynthesis*
D000900:Anti-Bacterial Agents; D001618:beta-Lactamases