Eleven Year Trends in Antimicrobial Non-Susceptibility among Klebsiella pneumoniae Isolates in the Veterans Health Administration

McDanel J, Goto M, Jones M, Franciscus CL, Alexander B, Richardson KK, Perencevich EN. Eleven Year Trends in Antimicrobial Non-Susceptibility among Klebsiella pneumoniae Isolates in the Veterans Health Administration. Poster session presented at: Society for Healthcare Epidemiology of America Annual Scientific Meeting; 2015 May 15; Orlando, FL.

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Background: Examining trends in non-susceptibility can aid in determining empiric therapy and infection control for patients with Klebsiella pneumoniae (KPN) infections. This study reports non-susceptibility rates for carbapenems (CAR), cephalosporins (CEP), aminoglycosides (AG), and fluoroquinolones (FQ) among KPN isolates from patients admitted to Veterans Health Administration (VHA) hospitals. Methods: This retrospective study included all patients admitted to 133 VHA hospitals during 2003-2013 who had positive blood cultures for KPN with available susceptibility testing results. Only the first isolate per patient admission per year was included in the analysis. Non-susceptible isolates were resistant or intermediate to at least one agent from that antimicrobial class. For isolates lacking CAR susceptibility results, isolates susceptible to other beta-lactams were considered susceptible to CAR. Geographic divisions were defined by the U.S. Census Bureau. Isolates were categorized as community-onset (cultures collected < 48 hours) and hospital-onset (collected 48 hours). The Cochran-Armitage test for trend was used to compare rates over time. Results: There were 11,911 KPN isolates identified from 11,638 patients. Susceptibility results were provided for 9,095 (76%) CAR isolates, 11,798 (99%) AG isolates, 11,479 (96%) FQ isolates, 11,743 (99%) first and second generation (GEN) CEP isolates, and 11,540 (97%) third and fourth GEN CEP isolates. Throughout 2003-2013, non-susceptible rates ranged from 6.0%-10.4% (P = 0.87) for AG, 8.7%-14.0% (P = 0.11) for FQ, 12.2%-17.4% (P = 0.59) for first and second GEN CEP, 6.7%-11.4% (P = 0.08) for third and fourth GEN CEP, and 0.0%-4.4% (P < 0.01) for CAR (Figure). Non-susceptible rates for CAR were higher for hospital-onset (range: 0.0%-8.3%) than community-onset (range: 0.0%-2.4%) infections. Non-susceptible CAR rates varied by region [lowest: East South Central region (0.2%); highest: the Mid-Atlantic region (10.0%)]. Conclusion: Non-susceptible rates increased for CAR among the KPN isolates with significant regional variation. Providers should guide empiric therapy based on the non-susceptibility rates for their region especially when considering treatment with CAR.