379. Prevalence and Risk Factors of a Novel Piperacillin/Tazobactam-Non-Susceptible, β-lactam-Pan-Susceptible (TZP-NS/BL-PS) Phenotype in Enterobacteriaceae
Session: Poster Abstract Session: HAI: Multi Drug Resistant Gram Negatives
Thursday, October 27, 2016
Room: Poster Hall
Posters
  • TZP NS_ID Week Poster.pdf (119.4 kB)
  • Background: Our group has recently identified a novel phenotypic profile among Escherichia coli and Klebsiella pneumoniae portraying TZP MICs ≥ 32 μg/mL (non-susceptible due to porin mutation) while retaining susceptibility to other β-lactams in 30 hospitals across the US. This phenotype could have implications for TZP, which is often prescribed empirically and cascaded (i.e., hidden) by the lab. We describe the prevalence of this phenotype at our hospital and the risk factors for acquisition.

    Methods: A retrospective study was conducted for patients presenting to Hartford Hospital between Jan 2012 and Dec 2015. Patient characteristics, source, risk factors for acquisition, and course of infection are reported.

    Results: Of 7508 patients with E. coli and K. pneumoniae isolated, 38 (0.5%) had TZP-NS/BL-PS isolated. Twenty-two (58%) were admitted to the hospital; the other 16 had the organism isolated in the ED but were discharged directly. Of the 22 isolates from admitted patients, 12 (55%) were E. coli, 11 (50%) were healthcare-associated, 6 (27%) community-acquired, and 5 (23%) hospital-acquired. TZP-NS/BL-PS strains were predominately isolated from urine [16 (73%)], followed by blood and soft tissue. Patient mean age was 66 ± 20 years, and most [21 (95%)] had at least one typical risk factor for resistance. The most common were previous admission within 6 months (68%), infection within 6 months (64%), and presence of an indwelling catheter (41%). Nine (41%) patients previously received a β-lactam; 2 (9%) received TZP. Fourteen (64%) of these isolates caused symptomatic infection; all were successfully treated with a β-lactam [ceftriaxone, 11 (71%)], fluoroquinolone, or TMP/SMZ. Two patients were treated with TZP, had initial clinical response and were then de-escalated after culture results.

    Conclusion: The prevalence of TZP-NS/BL-PS Enterobacteriaceae at our hospital over the last 4 years was low. All infected patients were successfully treated with available antibiotics reported by our lab. Most patients with TZP-NS/BL-PS isolates had conventional risk factors for resistance, but few received TZP previously. The common empiric use of TZP justifies consideration of this phenotype during susceptibility testing in hospitalized patients.

    Abrar Thabit, PharmD, BCPS1,2, Joseph Kuti, PharmD1, Jaber Aslanzadeh, PhD3 and David Nicolau, PharmD, FCCP, FIDSA1, (1)Ctr. for Anti-Infect. Res. & Dev., Hartford Hospital, Hartford, CT, (2)Faculty of Pharmacy, King Abdulaziz University, Jeddah, Saudi Arabia, (3)Pathology and Laboratory Medicine, Hartford Hospital, Hartford, CT

    Disclosures:

    A. Thabit, None

    J. Kuti, None

    J. Aslanzadeh, None

    D. Nicolau, None

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