1843. Comparison of colistin non-susceptible Klebsiella pneumoniae and Pseudomonas aeruginosa isolates in an inner city hospital
Session: Poster Abstract Session: Antibacterial Susceptibility Surveillance
Saturday, October 29, 2016
Room: Poster Hall
  • IDWeek 2016 Colistin Non-S Klebsiella vs Pseudomonas 10_4_16.pdf (276.9 kB)
  • Background: The prevalence of infections due to colistin non-susceptible (CNS) gram-negative bacilli is increasing worldwide. We have had an increase of CNS Klebsiella pneumoniae (KP) and Pseudomonas aeruginosa (PA) isolates in our inner city medical center and have noted differences in patient factors and therapies.

    Methods: Adult patients with infection or colonization due to CNS KP and/or PA (colistin MIC >2 mcg/mL) within a 6.5-year period were identified for inclusion in a retrospective study. Patient, microbiological, treatment, and outcome data parameters were collected from the hospital electronic medical record. The epidemiology and treatment outcomes of patients with cultures positive for CNS KP and PA were evaluated and compared using descriptive and univariate analysis.

    Results: A total of 113 CNS isolates were included in the study – 68 KP isolates (60%) and 45 PA isolates (40%). The median colistin MIC was 7 µg/mL for CNS KP isolates and 4 µg/mL for CNS PA isolates. CNS PA was most commonly isolated from respiratory specimens (55%), while the majority of CNS KP (47%) was isolated from a urinary source. CNS KP bacteremia was observed in 18% of the study cohort, but no patients had CNS PA isolated from blood cultures. A comparable number of antimicrobials were used in both groups (mean of 2 in KP group vs. 1.9 in PA group). 78% of patients with CNS PA infection received appropriate antimicrobial therapy compared to only 59% of the CNS KP subgroup. Antibiotic treatment regimens most frequently included carbapenems, aminoglycosides and tigecycline (for KP isolates). 35% of patients in the KP group received colistin within the preceding year versus 11% in the PA group. Hospital mortality rates were similar between the 2 groups (35 % in KP group vs. 31% in PA group).

    Conclusion: KP isolates had higher colistin MICs and were more likely to be associated with urinary tract infections compared to CNS PA, which were commonly associated with respiratory tract infections. Combination antibiotic regimens, including carbapenems and aminoglycosides, were used to treat infections in both subgroups. Mortality rates were high (over 30%) in patients with CNS KP and PA infections.

    Shin-Pung Jen, PharmD1, Erina Khadka Kunwar, MD2 and Lisa Dever, MD2, (1)Pharmacy, University Hospital, Newark, NJ, (2)Division of Infectious Diseases, Rutgers New Jersey Medical School, Newark, NJ


    S. P. Jen, None

    E. Khadka Kunwar, None

    L. Dever, None

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