1435. Risk Factors and Subtype Analysis for Extended Spectrum Beta-Lactamase (ESBL) Producing Escherichia coli and Klebsiella Species with Community-Associated or Hospital-Associated Infection Between 2003-May 2011
Session: Poster Abstract Session: Epidemiology of Multiple Drug-Resistant Gram Negative Rods
Saturday, October 20, 2012
Room: SDCC Poster Hall F-H

Background: ESBL-producing organisms have been identified with increasing frequency in patients without prior hospital exposure.   The purpose of this study is to review the incidence of ESBL-producing Escherichia coli or Klebsiella species over a 7-year period and compare the risk factors for infection and incidence of CTX, SHV and TEM ESBL subtypes between patients with community associated (CA) versus hospital associated (HA) infection.

Methods: An electronic records search was performed and unique patient ESBL-producing organisms were identified.  These isolates are identified with the Vitek2 GNI card and frozen for future infection control analysis. A retrospective chart review assessed for risk factors for infection.  True infection was defined by source with symptoms and culture growth.  HA infection was patients with hospital stay, long-term care facility, surgery or chronic dialysis within 3 months of clinical culture. PCR with universal primers for TEM, SHV and CTX subtypes was performed.   Risk factors for infection, ESBL subtype and antibiotic susceptibility were compared for HA and CA infection.   

Results: A total of 150 unique patient isolates were identified with 28 excluded for not being a true infection.  From 2005 to 2010, the incidence of ESBL in E coli increased from 0.13% to 1.0%, while the incidence in Klebsiella remained 1.0-1.3%.  CA infection was more likely in females (p<0.01), age <60 (p<0.01), urinary source (p<0.01) and recurrent UTIs (p=0.02).  HA infection was more likely in males (p<0.01), age>60 (p<0.001), diabetes (p<0.01), cardiovascular disease (p<0.01), malignancy (p<0.01) and antibiotics within 3 months (p=0.01). 58 isolates underwent PCR and CTX subtype was more likely to be CA (p=<0.01), E coli (p<0.01) and sensitive to nitrofurantoin (p<0.01); no susceptibility differences to FQ (34% S) or TMP/SMX (40% S) were present. 

Conclusion: This is one of the 1st characterizations of ESBL-producing organisms in the Pacific Northwest revealing an increased incidence over 7 years particularly in the community setting with younger females with E coli UTIs of the CTX subtype.  Resistance to FQ or TMP/SMX was high in both HA and CA infection, making the task of appropriate empiric antibiotics more difficult.

Michael Koren, MD, Steven Mahlen, PhD, Samandra Demons, PhD and Christina Schofield, MD FACP, Madigan Army Medical Center, Tacoma, WA


M. Koren, None

S. Mahlen, None

S. Demons, None

C. Schofield, None

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