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280 Predictors and outcomes of patients with carbapenem-resistant Enterobacteriaceae co-colonized with Acinetobacter baumannii or Pseudomonas aeruginosa

Saturday, April 2, 2011
Trinity Ballroom (Hilton Anatole)
Dror Marchaim, MD , Detroit Medical Center, Wayne State University, Detroit, MI
Federico Perez , Cleveland VA Medical Center, Cleveland, OH
Kayoko Hayakawa, MD, PhD , Detroit Medical Center, Wayne State University, Detroit, MI
Palaniappan Manickam, MD, MPH , Detroit Medical Center, Wayne State University, Detroit, MI
Paul R. Lephart, PhD , Detroit Medical Center, Wayne State University, Detroit, MI
Suchitha Bheemreddy, MD , Detroit Medical Center, Wayne State University, Detroit, MI
Bharath Sunkara, MD , Detroit Medical Center, Wayne State University, Detroit, MI
Christopher Blunden, BS , Detroit Medical Center,Wayne State University, Detroit, MI
Andrea M. Hujer, BA , Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center,, Cleveland, OH
Susan Rudin, BA , Louis Stokes Cleveland VA Medical Center, Cleveland, OH
Maryann Shango, BS , Detroit Medical Center, Wayne State University, Detroit, MI
Michelle Campbell, BA , Detroit Medical Center, Wayne State University, Detroit, MI
Jastin Varkey, BA , Detroit Medical Center, Wayne State University, Detroit, MI
Diixa Patel, MD , Detroit Medical Center, Wayne State University, Detroit, MI
Teena Chopra, MD , Detroit Medical Center, Wayne State University, Detroit, MI
Jason M. Pogue, PharmD , Detroit Medical Center, Wayne State University, Detroit, MI
Sorabh Dhar, MD , Detroit Medical Center, Wayne State University, Detroit, MI
Robert A. Bonomo, MD , Louis Stokes Cleveland VA Medical Center, Cleveland, OH
Keith S. Kaye, MD, MPH , Detroit Medical Center, Wayne State University, Detroit, MI
Background: As previously reported by our group, in a Carbapenem-resistant Enterobacteriaceae (CRE) cohort from Detroit, co-colonization with Acinetobacter baumannii or Pseudomonas aeruginosa (non-fermenters) was the strongest independent factor associated with colistin resistance and increased in-hospital mortality. 

Objective: Study aims were to identify predictors and additional outcomes associated with co-colonization with non-fermenters. 

Methods: CREs isolated from 09/2008 to 09/2009 were analyzed at Detroit Medical Center (DMC). Patients who had an additional isolation of a non-fermenter, during the time period of 7 days before to 7 days after CRE isolation, were considered to be co-colonized. High level of carbapenem resistance was defined as MIC≥4 μg/mL to imipenem or meropenem. Rep-PCR of the CRE was used to determine genetic similarity among the co-colonized group of patients.

Results: Ninety-two unique patient CRE isolates were recovered during the study period. Sixty-eight (74%) strains were Klebsiella pneumoniae, 7 Klebsiella oxytoca, 15 Enterobacter spp., and 2 Escherichia coli. Thirty-four (40%) patients were co-colonized with non-fermenters and in 26 instances (79%) the non-fermenter isolate was isolated on the same day as the CRE isolate. In multivariate analysis, recent LTAC stay (OR=2.7, p=0.03), recent ICU stay (OR=5.4, p=0.044), high Charlson’s score (OR=1.5, p=0.004), and prior treatment with antimicrobials active only against Gram-positives (vancomycin, linezolid, daptomycin) (OR=3.2, p=0.03), were all significant predictors for co-colonization. CREs from co-colonizers had higher rates of resistance to carbapenems (OR=2.9, p=0.02). In multivariate outcome models, co-colonization was independently associated with increased 3-month mortality rate (OR=3.5, p=0.01) and additional hospitalization/s in the following 6 months (OR=3.2, p=0.015). Rep-PCR revealed polyclonality among the CREs recovered from the co-colonizers.

Conclusions: Recent LTAC residence and exposure to antibiotics with only Gram-positive activity were independent risk factors for co-colonization. In addition to increased mortality, co-colonization was associated with hospital re-admissions and increased MICs of CREs to carbapenems.  The potential for transfer of some of the genes conferring resistance, from non-fermenters to CREs, should be further investigated.