disk diffusion
MinireviewCefiderocol Antimicrobial Susceptibility Testing Considerations: the Achilles' Heel of the Trojan Horse?Cefiderocol (formerly S-649266) is a novel siderophore-conjugated cephalosporin with activity against a broad array of multidrug-resistant (MDR), aerobic Gram-negative bacilli. The siderophore component binds iron and uses active iron transport for drug entry into the bacterial periplasmic space. The cephalosporin moiety is the active antimicrobial component, structurally resembling a hybrid between ceftazidime and cefepime. Like other...
BacteriologyCefiderocol Antimicrobial Susceptibility Testing against Multidrug-Resistant Gram-Negative Bacilli: a Comparison of Disk Diffusion to Broth MicrodilutionAntimicrobial susceptibility testing (AST) of cefiderocol poses challenges because of its unique mechanism of action (i.e., requiring an iron-depleted state) and due to differences in interpretative criteria established by the Clinical and Laboratory Standards Institute (CLSI), U.S. Food and Drug Administration (FDA), and European Committee on Antimicrobial Susceptibility Testing (EUCAST). Our objective was to compare cefiderocol disk...
BacteriologyEvaluation of Surrogate Tests for the Presence of mecA-Mediated Methicillin Resistance in Staphylococcus capitis, Staphylococcus haemolyticus, Staphylococcus hominis, and Staphylococcus warneriTesting of staphylococci other than Staphylococcus aureus (SOSA) for mecA-mediated resistance is challenging. Isolates of Staphylococcus capitis, Staphylococcus haemolyticus,...
BacteriologyTesting of In Vitro Susceptibility of Neisseria gonorrhoeae to Azithromycin: Comparison of Disk Diffusion and Reference Agar Dilution MethodsAzithromycin in combination with ceftriaxone is recommended as the first-line treatment for uncomplicated gonorrhea in many countries. Therefore, monitoring of azithromycin susceptibility of Neisseria gonorrhoeae isolates is essential. In 2019, the Clinical and Laboratory Standards Institute (CLSI) listed the MIC breakpoint for a susceptible-only category to...
BacteriologyImipenem-Relebactam Susceptibility Testing of Gram-Negative Bacilli by Agar Dilution, Disk Diffusion, and Gradient Strip Methods Compared with Broth MicrodilutionThis study aimed to determine whether agar dilution, research-use-only disk diffusion (Mast Group Ltd., Bootle Merseyside, UK), Etest (bioMérieux, Inc., Durham, NC), and MIC test strip (MTS) (Liofilchem, Inc., Waltham, MA) methods yield equivalent results to those of broth microdilution (BMD) for imipenem-relebactam susceptibility testing using a collection of 297 Gram-negative bacilli, including members of the order ...
BacteriologyCorrelation between Broth Microdilution and Disk Diffusion Results when Testing Ceftazidime-Avibactam against a Challenge Collection of Enterobacterales Isolates: Results from a Multilaboratory StudyWe assessed the ceftazidime-avibactam disk diffusion breakpoints that provide the lowest discrepancy error rates by testing an Enterobacterales isolate collection with ceftazidime-avibactam MIC values near the breakpoints. Isolates (n = 112) were susceptibility tested by broth microdilution and disk diffusion methods in 3 laboratories. Current disk diffusion...
BacteriologyEvaluation of Oxacillin and Cefoxitin Disk Diffusion and Microbroth Dilution Methods for Detecting mecA-Mediated β-Lactam Resistance in Contemporary Staphylococcus epidermidis IsolatesMethicillin (β-lactam) resistance in Staphylococcus epidermidis is mediated by the mecA gene, with resistance reported to be as high as 90%. The goal of this study was to evaluate oxacillin and cefoxitin disk diffusion (DD) and broth microdilution (BMD) methods for the detection of mecA-mediated β-lactam resistance in 100 human isolates of...
BacteriologyA Multicenter Study To Evaluate Ceftaroline Breakpoints: Performance in an Area with High Prevalence of Methicillin-Resistant Staphylococcus aureus Sequence Type 5 LineageCeftaroline (CPT) is a broad-spectrum agent with potent activity against methicillin-resistant Staphylococcus aureus (MRSA). The sequence type 5 (ST5) Chilean-Cordobés clone, associated with CPT nonsusceptibility, is dominant in Chile, a region with high rates of MRSA infections.
BacteriologyEvaluation of Ciprofloxacin and Levofloxacin Disk Diffusion and Etest Using the 2019 Enterobacteriaceae CLSI BreakpointsIn 2019, the Clinical and Laboratory Standards Institute (CLSI) published revisions to the Enterobacteriaceae ciprofloxacin and levofloxacin breakpoints. We evaluated the performance of disk diffusion and Etest compared to that of reference broth microdilution by use of the revised breakpoints.
