Carbapenem resistance in Klebsielia pneumoniae not detected by automated susceptibility testing

• Authors: Fred Tenover, Emory University; Rajinder K. Kalsi, Centers for Disease Control and Prevention; Portia P. Williams, Rollins School of Public Health; Roberta B. Carey, Centers for Disease Control and Prevention; Sheila Stocker, Centers for Disease Control and Prevention; David Lonsway, Centers for Disease Control and Prevention; J. Kamile Rasheed, Centers for Disease Control and Prevention; James W. Biddle, Centers for Disease Control and Prevention; John McGowan Jr., Emory University; Bruce Hanna, Rollins School of Public Health
• Journal Title: Emerging Infectious Diseases
• Volume: Volume 12, Number 8
• Publisher: Centers for Disease Control | 2006-08-01, Pages 1209-1213
• Type of Work: Article | Final Publisher PDF
• Publisher DOI: http://doi.org/10.3201/eid1708.060291
• Subjects: Health Sciences, Medicine and Surgery
• Keywords: Science & Technology; Life Sciences & Biomedicine; Immunology; Infectious Diseases; HYDROLYZING BETA-LACTAMASE; NEW-YORK-CITY; PSEUDOMONAS-AERUGINOSA; IMIPENEM; KPC-2; ENTEROBACTERIACEAE; EMERGENCE; OUTBREAK; BROOKLYN; SYSTEM

Abstract

Detecting β-lactamase-mediated carbapenem resistance among Klebsiella pneumoniae isolates and other Enterobacteriaceae is an emerging problem. In this study, 15 blaKPC-positive Klebsiella pneumoniae that showed discrepant results for imipenem and meropenem from 4 New York City hospitals were characterized by isoelectric focusing; broth microdilution (BMD); disk diffusion (DD); and MicroScan, Phoenix, Sensititre, VITEK, and VITEK 2 automated systems. All 15 isolates were either intermediate or resistant to imipenem and meropenem by BMD; 1 was susceptible to imipenem by DD. MicroScan and Phoenix reported 1 (6.7%) and 2 (13.3%) isolates, respectively, as imipenem susceptible. VITEK and VITEK 2 reported 10 (67%) and 5 (33%) isolates, respectively, as imipenem susceptible. By Sensititre, 13 (87%) isolates were susceptible to imipenem, and 12 (80%) were susceptible to meropenem. The VITEK 2 Advanced Expert System changed 2 imipenem MIC results from ≥16 μg/mL to ≤2 μg/mL but kept the interpretation as resistant. The recognition of carbapenem-resistant K. pneumoniae continues to challenge automated susceptibility systems.