Shio-Shin Jean1, Chun-Hsing Liao2, Wang-Huei Sheng3, Wen-Sen Lee4, Po-Ren Hsueh5. 1. Emergency Department, Department of Emergency and Critical Care Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan. 2. Department of Internal Medicine, Far Eastern Memorial Hospital, New Taipei City, Taiwan. 3. Department of Internal Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan. 4. Division of Infectious Diseases, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan. 5. Department of Internal Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan; Department of Laboratory Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan. Electronic address: hsporen@ntu.edu.tw.
Abstract
BACKGROUND/ PURPOSE: The aim of this study was to investigate the cefoperazone-sulbactam (CFP-SUL) susceptibilities of important Gram-negative bacteria (GNB) by agar dilution (reference method), disk diffusion, and two automated methods. METHODS: A total of 799 GNB isolates, including Enterobacteriaceae (n = 500) and nonfermentative GNB (NFGNB, n = 299), were recovered from various clinical specimens collected at National Taiwan University Hospital, Taipei, Taiwan from November 2013 to December 2014. The agar dilution method, disk diffusion method, and two automated susceptibility systems (Phoenix and Vitek 2) were used for testing susceptibility of the isolates to CFP-SUL. Categories of susceptibility (susceptible, intermediate, or resistant) to CFP-SUL yielded from each method were interpreted according to CFP-SUL interpretive breakpoints proposed previously. The results of categorical agreement and errors obtained between the agar dilution method and the other three methods were analyzed. RESULTS: The Vitek 2 system had the highest error rates against Escherichia coli (n = 150) and Enterobacter cloacae (n = 77) isolates, i.e., 6.7% and 11.7% minor errors, 8.5% and 1.7% major errors, and 40% and 20% very major errors, respectively. Additionally, the Vitek 2 system was also found to have a significantly lower sensitivity (44.4%) and lower positive predictive value (18.2%) for detecting CFP-SUL nonsusceptible E. coli isolates than other methods. For carbapenem-nonsusceptible Enterobacteriaceae isolates, the Vitek 2 system failed to detect correct susceptibility to CFP-SUL. The three methods failed to correctly detect CFP-SUL susceptibility categories against all NFGNB isolates except Pseudomonas aeruginosa. CONCLUSION: The Vitek 2 system is a suboptimal method in correctly detecting CFP-SUL susceptibility categories for E. coli, E. cloacae, and carbapenem-nonsusceptible Enterobacteriaceae isolates.
BACKGROUND/ PURPOSE: The aim of this study was to investigate the cefoperazone-sulbactam (CFP-SUL) susceptibilities of important Gram-negative bacteria (GNB) by agar dilution (reference method), disk diffusion, and two automated methods. METHODS: A total of 799 GNB isolates, including Enterobacteriaceae (n = 500) and nonfermentative GNB (NFGNB, n = 299), were recovered from various clinical specimens collected at National Taiwan University Hospital, Taipei, Taiwan from November 2013 to December 2014. The agar dilution method, disk diffusion method, and two automated susceptibility systems (Phoenix and Vitek 2) were used for testing susceptibility of the isolates to CFP-SUL. Categories of susceptibility (susceptible, intermediate, or resistant) to CFP-SUL yielded from each method were interpreted according to CFP-SUL interpretive breakpoints proposed previously. The results of categorical agreement and errors obtained between the agar dilution method and the other three methods were analyzed. RESULTS: The Vitek 2 system had the highest error rates against Escherichia coli (n = 150) and Enterobacter cloacae (n = 77) isolates, i.e., 6.7% and 11.7% minor errors, 8.5% and 1.7% major errors, and 40% and 20% very major errors, respectively. Additionally, the Vitek 2 system was also found to have a significantly lower sensitivity (44.4%) and lower positive predictive value (18.2%) for detecting CFP-SUL nonsusceptible E. coli isolates than other methods. For carbapenem-nonsusceptible Enterobacteriaceae isolates, the Vitek 2 system failed to detect correct susceptibility to CFP-SUL. The three methods failed to correctly detect CFP-SUL susceptibility categories against all NFGNB isolates except Pseudomonas aeruginosa. CONCLUSION: The Vitek 2 system is a suboptimal method in correctly detecting CFP-SUL susceptibility categories for E. coli, E. cloacae, and carbapenem-nonsusceptible Enterobacteriaceae isolates.
Authors: Ana Rita Rebelo; Valeria Bortolaia; Pimlapas Leekitcharoenphon; Dennis Schrøder Hansen; Hans Linde Nielsen; Svend Ellermann-Eriksen; Michael Kemp; Bent Løwe Røder; Niels Frimodt-Møller; Turid Snekloth Søndergaard; John Eugenio Coia; Claus Østergaard; Henrik Westh; Frank M Aarestrup Journal: Front Microbiol Date: 2022-06-10 Impact factor: 6.064