1598. Epidemiology of CTX-M-type extended-spectrum ?-lactamase (ESBL)-producing Escherichia coli among older adults
Session: Poster Abstract Session: Multidrug-Resistant Gram Negative Rods
Saturday, October 5, 2013
Room: The Moscone Center: Poster Hall C

Background : ESBL-E. coli (ESBLEC), especially CTX-M-type ESBL-E. coli (CTXMEC) have emerged as a major clinical problem worldwide, and in many locales have spread to the community. The epidemiology of the isolation of CTXMEC among older adults, which include >10% of US population, is not well known. We conducted a case-control study to identify independent risk factors for recovery of CTXMEC in older adults, in a large U.S. medical center located in southeast Michigan.

Methods : Unique older adults (≥ 65 year old) with clinical ESBLEC isolation during the study period (2/2010 –7/2011) were included. PCR analysis for the detection of CTX-M-beta-lactamase genes was conducted. Patients with CTXMEC whose detailed medical records were available (cases) were matched to uninfected controls (≥ 65 year old) in a 1:1 ratio.

Results : Eighty-seven CTXMEC cases (72 [82.8%] CTX-M-15-type) were identified from urine (n=65); sputum (n=9); wounds (n=7); and blood (n=5).  These cases were matched to 87 uninfected controls.  The mean age of the study cohort was 78.1ą8.7 years and 85 (48.9%) were male. Independent risk factors for the isolation of CTXMEC were determined (Table). In-hospital mortality was similar between two groups (7.1% vs 7.0%); 3 month mortality rates were higher in CTXMEC group than controls (20.3% vs 11.5%, p=0.05). Median total length of hospital days was greater among CTXMEC cases than controls (9 [IQR: 6-15] vs 5 [3-8], p<0.001). In 65 (74.7%) cases, CTXMEC was present at the time of hospital admission (isolated within 48 hours of admission). Nine (10.3%) of CTXMEC cases did not have recent health care contact; of these, 5 also did not have recent antibiotic exposure.

Conclusion : Non-home residence, multiple comorbidities, and catheter use were independently associated with isolation of CTXMEC among older adults. Antimicrobial exposure was not a risk factor for the CTXMEC isolation. CTXMEC are prevalent outside hospitals among older adults in the US.

Table. Multivariate analysis of risk factors for the isolation of CTXMEC

among older adultsA


CTXMEC cases vs

uninfected controls

Odds ratio

(95% CI)

P value

Charlson combined comorbidity index (≥5)

13.10 (1.62-105.70)


Indwelling urinary catheter

3.47 (1.29-9.30)


Non-home residence

3.16 (1.10-9.10)


A Controlled for history of urinary tract infection

Sachi Matsubayashi1, Sameen Farooq2, Kayoko Hayakawa, M.D., PhD2,3, Dror Marchaim, MD2 and Keith Kaye, MD, MPH, FIDSA, FSHEA4, (1)Jikei University School of Medicine, Tokyo, Japan, (2)Detroit Medical Center (DMC) / Wayne State University, Detroit, MI, (3)Disease Control and Prevention Center, National Center for Global Health and Medicine, Tokyo, Japan, (4)Infectious Diseases, Detroit Medical Center/ Wayne State University, Detroit, MI


S. Matsubayashi, None

S. Farooq, None

K. Hayakawa, None

D. Marchaim, None

K. Kaye, None

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