July 2007 – Clark County Antibiogram
Linda Verchick, MS and Jing Feng, MS

Introduction:

In 2003, the Southern Nevada Health District (SNHD) Office of Epidemiology (OOE), in conjunction with Nevadans for Antibiotic Awareness (NAA), began recruiting local commercial and hospital laboratory cooperation for a county-wide antimicrobial resistance surveillance project.

The goal of this project is to identify the susceptibility patterns of bacterial pathogens in Clark County and present this information to local health care providers as a reference tool when prescribing antimicrobial medications.

SNHD staff is attempting to obtain as many positive culture results as possible in order to ensure the representativeness of the countywide antibiograms. Participating hospitals will receive a facility specific report along with an aggregate hospital report contingent upon data availability and quality.

Hospital and commercial laboratories should contact SNHD OOE at (702) 759-1299 if interested in participating in this project.

Methods:

Due to the variation in data output from automated systems used for microbial identification and susceptibility testing among laboratories in Clark County, patient-based electronic data from participating facilities are submitted in miscellaneous text/data formats.

The different data formats pose challenges for the records aggregation required to produce a countywide antibiogram. Specialized data extraction and conversion programs* were written to obtain data from various semi-structured files and to arrange them into desired formats. Data of usable formats were further processed to reconcile differences in organism and antimicrobial naming schemes across different laboratories.

Each facility’s data were eventually transformed to SAS (Statistical Analysis Software) data sets for aggregation and unduplication. The unduplication procedure checks an isolate from a patient against the most current isolate of the same organism from the same patient (if present in the aggregated data), and removes the isolate if the time interval between test results had been less than 30 days. Unduplication is necessary because patients may have been tested by multiple facilities or multiple times. It also helps ensure that results reported on the antibiogram are not biased in favor of more resistant isolates.

On thes antibiograms we have chosen to include those antimicrobials which are recommended by the January 2006 Performance Standards for Antimicrobial Susceptibility Testing set forth by the Clinical and Laboratory Standards Institute (CLSI) or those that are routinely tested.

Results:

One major commercial laboratory and five hospital laboratories currently participate in this project. Participants are asked to send quarterly data to SNHD. These data represent the majority of all culture positive results in Clark County.

The antibiogram PDF (80 kb/3 pages) contains data from January 2005 through December 2006 and is now available in three versions: all age groups, adult only and pediatric only. A black-and-white PDF (78 kb/3 pages) version is offered as it affords greater clarity for people who don't want to print in color.

Quarterly updates will be made as data are received from participating facilities. Future newsletters will include additional analyses on select organisms. Providers interested in obtaining information on antimicrobials not included in this antibiogram can contact Linda Verchick or Jing Feng at the SNHD OOE Monday through Friday at (702) 759-1299 between 8 a.m. and 4:30 p.m.

*Made possible by Sierra Health Services in-kind donation of programmer staff to NAA.

SNHD Epidemiology Newsletters are available at: www.southernnevadahealthdistrict.org/physician/epi_newsletter.htm

Reference:

Clinical and Laboratory Standards Institute. Performance Standards for Antimicrobial Susceptibility Testing; Sixteenth Informational Supplement. CLSI document M 100-S-16 [ISBN 1-56238-588-7].

For more information please email the Office of Epidemiology.