178. Predicting Increased Resistance of Gram-negative Infections (PIROGI)
Session: Poster Abstract Session: Antimicrobial Stewardship: Current State and Future Opportunities
Thursday, October 8, 2015
Room: Poster Hall
  • PIROGI final poster.pdf (272.3 kB)
  • Background: It is common practice to initiate two antibiotics from different classes when a serious gram-negative (GN) infection is suspected.  Typically, this “double coverage” includes a b-lactam (Piperacillin-Tazobactam, “P-T”, or cefepime, “CEF”), as the primary agent, and either an aminoglycoside or fluoroquinolone as the second agent.  Other agents may be substituted in patients at risk for highly-resistant organisms.  The ability to use clinical parameters to predict the need for antibiotics with enhanced activity against resistant GNs would be beneficial.

    Methods: A retrospective analysis was undertaken of all GN isolates from blood cultures from a large 3 hospital health system from 2010-2013. Our study cohort had bacteremia non-susceptible (NS) to P-T or CEF from inpatients ≥ 18 years of age. Our control cohort was inpatients with blood isolates susceptible to both.  Prior antibiotics, prior cultures, demographics, and NS rates for ciprofloxacin (CIP), gentamicin (GENT), tobramycin (TOBRA), and amikacin (AMI) were examined.

    Results: Patients in the study group had received an average of 3.2 different antibiotics, whereas those in the control group received an average of 1.4 (P<0.00001).  Mean age of patients in the study group was 68 years old, and 73 years old for the control group (p<0.0001).  Antibiotic NS rates between the study and control group also demonstrated statistically-significant differences, as follows: Study Group - CIP 67% NS, AMI 13.9% NS, TOBRA 45.8% NS, GENT 43.3% NS; Control Group - CIP 16.2% NS, AMI 0.4% NS, TOBRA 4.2% NS, GENT 4.4% NS.  As expected from antibiograms established at our institution, the highest NS rates occurred for CIP in our study group, and patients with isolates NS to AMI had the highest rates of NS to the other agents. 

    Conclusion: Patients with GN bacteremia resistant to CEF and/or P-T were exposed to a significantly greater variety of antibiotics in the preceding 90 days than those with less resistant organisms. In patients who are floridly septic who received >3 antibiotics in the prior 90 days consideration should be given for use AMI as a second line agent since in this group 7 out of 10 highly resistant isolates are NS to CIP whereas only 1.4 out of 10 are NS to AMI.

    Zachary Levine, MD, Infectious Diseases, Beaumont Health System, Royal Oak, MI, Matthew Sims, MD, PhD, FIDSA, Beaumont Health System, Royal Oak, MI, Adam Skrzynski, M.D., Infectious Diseases, Beaumont Health - Royal Oak, Royal Oak, MI, Nichole Mccaffrey, Medical Student, Oakland University William Beaumont School of Medicine, Auburn Hills, MI and Jacob Makin, MT, Microbiology, Beaumont Health System, Royal Oak, MI


    Z. Levine, None

    M. Sims, None

    A. Skrzynski, None

    N. Mccaffrey, None

    J. Makin, None

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