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.
A. Skrzynski, None
N. Mccaffrey, None
J. Makin, None
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