1483. Comparison of Outcomes in Urinary Tract Infections Caused by SPICE Organisms Treated with Non-Carbapenem-β-lactams vs. Non-β-lactams Agents

Abstract

BackgroundThe “SPICE organisms” intrinsically produce low levels of a chromosomally encoded β-lactamase enzyme, AmpC. When SPICE organisms are exposed to certain antimicrobial agents, they can select for de-repressed mutants and induce the AmpC gene. No study to date has determined the optimal treatment of lower inoculum infections such as urinary tract infections (UTIs) caused by SPICE organisms.MethodsThis study is a single-center, retrospective observational review of adult hospitalized patients with a UTI caused by a SPICE organism from November 2012 to November 2015. The objective of this study was to compare outcomes amongst patients with UTIs caused by select SPICE organisms treated with drugs susceptible to AmpC hydrolysis (penicillins, cephalosporins except cefepime, and monobactams) vs. drugs stable against AmpC (carbapenems, cefepime, and non-β-lactam agents). The primary outcome was clinical response, defined as resolution of signs and symptoms of UTI without requiring escalation of antimicrobial therapy after 48 hours of therapy initiation. Secondary outcomes include 30-day infection-related readmission, 30-day infection recurrence rate, 30-day all-cause mortality, and length of hospital stay. Patients with resistance to ceftriaxone were reviewed for β-lactam exposure (≥7 days) within the last month.ResultsOne-hundred 56 patients were identified. Clinical response, 30-day infection-related readmission, 30-day infection recurrence, 30-day mortality rates, and median length of hospital stay were similar between the AmpC stable and AmpC susceptible groups (Table 1). Notably, 39.1% of patients with ceftriaxone resistance reported had recent β-lactam exposure vs. only 11.6% of patients without ceftriaxone resistance (P = 0.0028).ConclusionBased our data, there does not appear to be a difference in clinical response, 30-day-related readmission, 30-day infection recurrence, 30-day all-cause mortality rates, or length of stay in patients with UTIs treated with AmpC stable and AmpC susceptible agents. AmpC induction can be seen with at least 7 days of β-lactam use in the past 30 days as demonstrated by more frequent use of recent β-lactam agents in those with ceftriaxone resistance detected. Disclosures All authors: No reported disclosures.