Clinical laboratory testing. Criteria for acceptable lots of dehydrated Mueller-Hinton agar and broth for antimicrobial susceptibility testing

2016 ◽  
Keyword(s):  
Antimicrobial Susceptibility ◽  
Laboratory Testing ◽  
Susceptibility Testing ◽  
Clinical Laboratory ◽  
Antimicrobial Susceptibility Testing ◽  
Mueller Hinton ◽  
Mueller Hinton Agar ◽  
Clinical Laboratory Testing ◽  
Testing Criteria

scholarly journals Performance of Etest for Antimicrobial Susceptibility Testing of Abiotrophia defectiva and Granulicatella Species: TABLE 1

2016 ◽  
Vol 54 (8) ◽  
pp. 2194-2196 ◽  
Author(s):  
Michael O. Alberti ◽  
Janet A. Hindler ◽  
Romney M. Humphries
Keyword(s):  
Antimicrobial Susceptibility ◽  
Susceptibility Testing ◽  
Antimicrobial Susceptibility Testing ◽  
Broth Microdilution ◽  
Mueller Hinton ◽  
Abiotrophia Defectiva ◽  
Mueller Hinton Agar

The Etest on chocolate Mueller-Hinton agar was compared to broth microdilution (BMD) for 125 isolates of nutritionally variant streptococci. Vancomycin Etests yielded 31.1% essential agreement (EA) and 20.0% categorical agreement (CA). Penicillin Etests yielded 86.0% EA and 85.6% CA, whereas ceftriaxone Etests yielded 73.6% EA and 68.0% CA.

scholarly journals Cefiderocol Antimicrobial Susceptibility Testing Considerations: the Achilles' Heel of the Trojan Horse?

2020 ◽  
Vol 59 (1) ◽  
pp. e00951-20 ◽  
Author(s):  
Patricia J. Simner ◽  
Robin Patel
Keyword(s):  
Antimicrobial Susceptibility ◽  
Susceptibility Testing ◽  
Antimicrobial Susceptibility Testing ◽  
Disk Diffusion ◽  
Research Use ◽  
Gram Negative ◽  
Content Type ◽  
Mueller Hinton

ABSTRACTCefiderocol (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 β-lactam agents, the principal bactericidal activity of cefiderocol occurs via inhibition of bacterial cell wall synthesis by binding of penicillin-binding proteins (PBPs) and inhibiting peptidoglycan synthesis, leading to cell death. Iron concentrations need to be taken into consideration when in vitro antimicrobial susceptibility to cefiderocol is determined. Broth microdilution (BMD) and disk diffusion methods have been developed to determine in vitro activity of cefiderocol. For BMD, cation-adjusted Mueller-Hinton broth (CAMHB) requires iron depletion to provide MICs predictive of in vivo activity. A method to prepare iron-depleted CAMHB (ID-CAMHB) has been described by the Clinical and Laboratory Standards Institute (CLSI). For disk diffusion, standard Mueller-Hinton agar is recommended, presumably because iron is bound in the medium. Currently, clinical FDA and European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints and investigational (research-use-only) CLSI breakpoints exist for interpreting cefiderocol susceptibility results for certain Gram-negative bacilli. Cefiderocol does not have clinically relevant activity against Gram-positive or anaerobic organisms. FDA or EUCAST breakpoints should be applied to interpret results for Enterobacterales, Pseudomonas aeruginosa, and Acinetobacter baumannii complex for patient care until the investigational status has been removed from CLSI breakpoints. Further clinical outcome data are required to assess the effectiveness of cefiderocol for treatment of other Acinetobacter species (non-baumannii complex) and Stenotrophomonas maltophilia at this time, and, as such, antimicrobial susceptibility testing of these organisms should be limited to research use in the scenario of limited treatment options.

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