Ease-of-use protocol for the rapid detection of third-generation cephalosporin resistance in Enterobacteriaceae isolated from blood cultures using matrix-assisted laser desorption ionization-time-of-flight mass spectrometry.
An ease-of-use protocol for the identification of resistance against third-generation cephalosporins in Enterobacteriaceae isolated from blood culture bottles was evaluated using matrix-assisted laser desorption ionization-time-of-flight mass spectrometry. A cefotaxime hydrolysis assay from chocolate agar subcultures using antibiotic discs and without inoculum standardization was developed for routine work flow, with minimal hands-on time. This assay showed good performance in distinguishing between cefotaxime-susceptible and cefotaxime-resistant strains, with excellent results for Escherichia coli (sensitivity 94.7%, specificity 100%). However, cefotaxime resistance was not detected reliably in Enterobacteriaceae expressing AmpC genes or carbapenemase-producing Klebsiella pneumoniae.
Unit of Microbiology, Department of Specialized, Diagnostic and Experimental Medicine, St. Orsola-Malpighi University Hospital, Bologna, Italy. Electronic address: claudio.foschi@gmail.com.
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Foschi
Unit of Microbiology, Department of Specialized, Diagnostic and Experimental Medicine, St. Orsola-Malpighi University Hospital, Bologna, Italy.
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Compri
Unit of Microbiology, Department of Specialized, Diagnostic and Experimental Medicine, St. Orsola-Malpighi University Hospital, Bologna, Italy.
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Smirnova
Unit of Microbiology, Department of Specialized, Diagnostic and Experimental Medicine, St. Orsola-Malpighi University Hospital, Bologna, Italy.
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Denicolò
Unit of Microbiology, Department of Specialized, Diagnostic and Experimental Medicine, St. Orsola-Malpighi University Hospital, Bologna, Italy.
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Nardini
Unit of Microbiology, Department of Specialized, Diagnostic and Experimental Medicine, St. Orsola-Malpighi University Hospital, Bologna, Italy.
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Tamburini
Unit of Microbiology, Department of Specialized, Diagnostic and Experimental Medicine, St. Orsola-Malpighi University Hospital, Bologna, Italy.
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Lombardo
Unit of Microbiology, Department of Specialized, Diagnostic and Experimental Medicine, St. Orsola-Malpighi University Hospital, Bologna, Italy.
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Landini
Unit of Microbiology, Department of Specialized, Diagnostic and Experimental Medicine, St. Orsola-Malpighi University Hospital, Bologna, Italy.
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Ambretti
D000900:Anti-Bacterial Agents / Q000378:metabolism; D000071997:Blood Culture; D002439:Cefotaxime / Q000378:metabolism; D018550:Cephalosporin Resistance; D004755:Enterobacteriaceae / Q000187:drug effects* / Q000302:isolation & purification; D006868:Hydrolysis; D008826:Microbial Sensitivity Tests / Q000379:methods*; D012680:Sensitivity and Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013997:Time Factors
D000900:Anti-Bacterial Agents; D002439:Cefotaxime
Blood culture bottles; Cefotaxime; Enterobacteriaceae; MALDI-TOF MS; Third-generation cephalosporin resistance