1420. Increasing Rates of Multi-Drug Resistant Organism Bloodstream Infections in a Comprehensive Cancer Center: Rifaximin as a Novel Alternative for Antimicrobial Prophylaxis
Session: Poster Abstract Session: Epidemiology of Multiple Drug-Resistant Gram Negative Rods
Saturday, October 20, 2012
Room: SDCC Poster Hall F-H

Background: Bloodstream infections caused by multi-drug resistant organisms (MDROs) are an increasing healthcare problem worldwide, especially in immunocompromised cancer patients. Fluoroquinolones are commonly used for prophylaxis of neutropenic fever, however development of resistance is risen. Rifaximin (RFX), a poorly absorbed oral antimicrobial with broad-spectrum activity, would be a novel alternative for prophylaxis.

Objectives: 1) To evaluate the prevalence of MDROs isolated from bloodstream infections (BSI) at MD Anderson Cancer Center; and 2) To determine the in-vitro susceptibility of RFX against these MDROs.

Methods: We retrospectively reviewed available microbiology data of MDROs causing BSI, including Vancomycin-resistant Enterococcus (VRE) and 5 gram-negative rods (GNRs) (E. coli [Ec], Klebsiella pneumoniae [Kp], Pseudomonas aeruginosa [Pa], Enterobacter sp. [Eb] and Acinetobacter sp. [Ac]) (Jan'09 - Dec'11). Available isolates were tested for in-vitro susceptibility to RFX (Sigma-Aldrich, MO) detecting the MIC (μg/ml), following CLSI guidelines.

Results: 110 (26.3%) of 419 Enterococcus were VRE, with yearly prevalence shown in Table 1) and 204 (13.5%) of 1506 were MDR-GNRs, The prevalence of MDR-GNRs increased significantly, from 10.6% in 2009 to 16.2% in 2011 (p=0.01). We recovered 31.0% VRE, 48.2% MDR-Ec, 50.0% MDR-Kp, 42.9% MDR-Pa, 50.0% MDR-Eb, and 50.0% MDR-Ac isolates. MICs of RFX showed in Table 1 were lower than reported RFX fecal concentration (7961 μg/g stool).

TABLE 1

2009

2010

2011

Total

MIC90

(range)

VRE

47/165

(28.5%)

30/132

(22.7%)

33/122

(27.0%)

110/419

(26.3%)

16

(0.03-256)

MDR-Ec

30/219

(13.7%)

33/223

(14.8%)

47/240

(19.6%)

110/682

(16.1%)

16

(0.01-64)

MDR-Kp

5/98

(5.1%)

10/97

(10.3%)

7/84

(8.3%)

22/279

(7.9%)

32

(0.25-32)

MDR-Pa

13/115

(11.3%)

20/104

(19.2%)

23/135

(17.0%)

56/354

(15.8%)

4

(0.5-32)

MDR-Eb

1/47

(2.1%)

3/55

(5.5%)

4/43

(9.3%)

8/145

(5.5%)

32

(8-32)

MDR-Ac

3/10

(30%)

2/21

(9.6%)

3/15

(20%)

8/46

(17.4%)

2

(0.01-2)

MDR-GNRs

52/489

(10.6%)

68/500

(13.6%)

84/517

(17.0%)

204/1506

(15.8%)

16

(0.01-64)

MDROs

99/654

(15.1%)

98/632

(15.5%)

117/639

(18.3%)

314/1925

(16.3%)

16

(0.01-256)

Conclusion: There was an increased prevalence of MDROs BSIs from 2009 to 2011. Also, RFX could be an alternative for antimicrobial prophylaxis in neutropenic patients, because of its high fecal concentration and adequate in-vitro activity.

Nobuyoshi Mori, MD1, Herbert DuPont, MD, FIDSA2, Zhi-Dong Jiang2, Aline El Zakhem, MD1, Polly Williams, MT, (ASCP)1, Audrey Van Tassel, BA2, Sherry Cantu, MPH1, Cindy Good, MT1, Tanya Dvorak, BS1, Ruth Reitzel, MS1, Jeffrey J. Tarrand, MD3, Issam Raad, MD1, Roy Chemaly, MD, MPH, FACP, FIDSA1 and Javier A. Adachi, MD, FIDSA1, (1)Infectious Diseases, Infection Control & Employee Health, The University of Texas MD Anderson Cancer Center, Houston, TX, (2)Center for Infectious Diseases, The University of Texas, School of Public Health, Houston, TX, (3)Laboratory Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX

Disclosures:

N. Mori, Advanced Clinical Research Organization: associate member, Educational grant

H. DuPont, Salix Pharmaceutical Company: Grant Investigator and Speaker's Bureau, Research grant and Speaker honorarium

Z. D. Jiang, None

A. El Zakhem, None

P. Williams, None

A. Van Tassel, None

S. Cantu, None

C. Good, None

T. Dvorak, None

R. Reitzel, None

J. J. Tarrand, None

I. Raad, None

R. Chemaly, None

J. A. Adachi, None

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