International Journal of Medical Microbiology and Tropical Diseases
  • Year: 2016
  • Volume: 2
  • Issue: 2

Direct reporting cefazolin from VITEK® 2 for E. coli, K. pneumoniae and P. mirabilis isolated from urine cultures using new CLSI interpretations

  • Author:
  • Jianhui Xiong1,, Bradley Langford2, Sigmund Krajden3,5, Zafar Hussain4, David Hancock1, Mark Downing2,3, William Chapman1,5
  • Total Page Count: 6
  • Page Number: 42 to 47

1Dept. of Laboratory Medicine, St. Joseph's Health Centre, Toronto, ON, Canada

2Antimicrobial Stewardship, St. Joseph's Health Centre, Toronto, ON, Canada

3Division of Infectious Diseases, St. Joseph's Health Centre, Toronto, ON, Canada

4(Retired), Microbiology Laboratories, London Health Science Centre, ON, Canada

5Dept. of Laboratory Medicine & Pathobiology, University of Toronto, ON, Canada

*Corresponding Author: Email: jianhuixenator@gmail.com

Online published on 19 September, 2016.

Abstract

In recent years, Clinical and Laboratory Standard Institute (CLSI) has recommended a series breakpoint changes for cefazolin, including testing it as a surrogate agent for oral cephalosporins for treating uncomplicated urinary tract infections (uUTIs).

This study was conducted to evaluate the feasibility of direct reporting the cefazolin results from VITEK® 2 for E.coli, K. pneumoniae, K. oxytoca and P. mirabilis isolated from patients with uUTIs using 2014 CLSI recommendation.

Cefazolin susceptibility results of urine cultures of the above four species generated from January 1, 2013 December 31, 2013, using both GN AST card N208 on VITEK®2 and cefazolin disk (gold standard) methods, were extracted from SoftMic Laboratory Information System and analyzed for their category agreement using 2014 CLSI interpretations.

Cefazolin susceptibilities of 1969 urinary isolates (1869 patients) of E. coli, K. pneumoniae/K. oxytoca and P. mirabilis comparing their VITEK®2 and disk test results, category agreement for cefazolin tested with both methods was 98%. The linear correlation between sensitive cefazolin and sensitive cephalothin MICs versus cefazolin zone diameters was good, with a predictive value of 99%.

It is acceptable to report cefazolin directly from VITEK®2 for the named species from urine cultures. The susceptibility correlation among cefazolin, cephalothin and cefixime were excellent (excluded non-susceptible), further testing with individual oral cephalosporin agents, in this institute, may not be necessary.

Final report accompanied by a comment in accordance with 2014 CLSI guideline is recommended to provide therapeutic guidance to clinicians.

Keywords

Cefazolin, Urine Culture, CLSI, Interpretations, VITEK®2