scholarly journals Comparison of Broth Microdilution, Etest, and Agar Disk Diffusion Methods for Antimicrobial Susceptibility Testing of Lactobacillus acidophilus Group Members

2008 ◽  
Vol 74 (12) ◽  
pp. 3745-3748 ◽  
Author(s):  
Sigrid Mayrhofer ◽  
Konrad J. Domig ◽  
Christiane Mair ◽  
Ulrike Zitz ◽  
Geert Huys ◽  
...  
Keyword(s):  
Antimicrobial Susceptibility ◽  
Lactobacillus Acidophilus ◽  
Susceptibility Testing ◽  
Inhibition Zone ◽  
Antimicrobial Susceptibility Testing ◽  
Disk Diffusion ◽  
Broth Microdilution ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Group Members

ABSTRACT In recent years, the absence of acquired antimicrobial resistance has become an important criterion to evaluate the biosafety of lactobacilli used as industrial starter or probiotic cultures. At present, however, standards for susceptibility testing of Lactobacillus strains or approved guidelines for interpreting the test results are not available. Hence, this study was carried out to contribute to the establishment of a standardized procedure for antimicrobial susceptibility testing of lactobacilli. The results obtained by testing 104 strains of the Lactobacillus acidophilus group were compared based on broth microdilution, disk diffusion, and Etest. Except for some specific agent-related effects, agreement between MICs resulting from the broth microdilution method and the Etest was good. In addition, inhibition zone diameters determined with disk diffusion correlated well with MICs from Etest and broth microdilution.

Improved Broth Microdilution Method for Antimicrobial Susceptibility Testing ofFrancisella Noatunensis Orientalis

2016 ◽  
Vol 28 (3) ◽  
pp. 199-207 ◽  
Author(s):  
Esteban Soto ◽  
Iona Halliday-Simmonds ◽  
Stewart Francis ◽  
Trellor Fraites ◽  
Beatriz Martínez-López ◽  
...  
Keyword(s):  
Antimicrobial Susceptibility ◽  
Susceptibility Testing ◽  
Antimicrobial Susceptibility Testing ◽  
Broth Microdilution ◽  
Microdilution Method ◽  
Broth Microdilution Method

scholarly journals Variation in erythromycin and clindamycin susceptibilities of Streptococcus pneumoniae by four test methods.

1997 ◽  
Vol 41 (1) ◽  
pp. 129-134 ◽  
Author(s):  
E L Fasola ◽  
S Bajaksouzian ◽  
P C Appelbaum ◽  
M R Jacobs
Keyword(s):  
Streptococcus Pneumoniae ◽  
Susceptibility Testing ◽  
Ambient Air ◽  
Test Methods ◽  
Disk Diffusion ◽  
Broth Microdilution ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Agar Dilution ◽  
Resistant Strains

Susceptibilities of 124 strains of Streptococcus pneumoniae to erythromycin and clindamycin were determined by the National Committee for the Clinical Laboratory Standards (NCCLS) broth microdilution method, with incubation for 20 to 24 h in ambient air and with modifications of this method by incubation for up to 48 h in air and CO2. Strains were also tested by agar dilution, E-test, and disk diffusion; good correlation was obtained with these methods, with clear separation into bimodal populations of susceptible and resistant stains. The broth microdilution method, however, using incubation in air for 24 h (NCCLS method), misclassified 4 of 92 erythromycin-resistant strains (1 as susceptible and 3 as intermediate) and 25 of 58 clindamycin-resistant strains (all as susceptible). With the exception of one strain with clindamycin, susceptible and resistant strains were correctly classified by the microdilution method with incubation in CO2 for 24 h or in ambient air for 48 h. Disk diffusion, agar dilution, and E-test methods with incubation in 5% CO2 are therefore reliable methods for susceptibility testing of pneumococci against these agents. However, the NCCLS microdilution method, which specifies incubation for 20 to 24 h in ambient air, produced significant very major errors (43%) clindamycin. Modification of the microdilution method by incubation in 5% CO2 or by extension of incubation time in ambient air to 48 h corrected these errors. Disk diffusion, however, was shown to be a simple, convenient, and reliable method for susceptibility testing of pneumococci to erythromycin and clindamycin and is suggested as the method of choice for these agents.

scholarly journals Comparative performances of Vitek-2, Disk Diffusion, and Broth Microdilution for antimicrobial susceptibility testing of canine Staphylococcus pseudintermedius

2021 ◽  
Author(s):  
Elisa Rampacci ◽  
Michele Trotta ◽  
Caterina Fani ◽  
Serenella Silvestri ◽  
Valentina Stefanetti ◽  
...  
Keyword(s):  
Antimicrobial Susceptibility ◽  
Susceptibility Testing ◽  
Antimicrobial Susceptibility Testing ◽  
Disk Diffusion ◽  
Health Concern ◽  
Broth Microdilution ◽  
Major Error ◽  
Staphylococcus Pseudintermedius ◽  
Cutaneous Infections ◽  
Vitek 2

Staphylococcus pseudintermedius is the primary cause of canine cutaneous infections and sporadically isolated as pathogen from humans. Rapidly emerging antibiotic-resistant strains are creating serious health concern so that accurate and timely antimicrobial susceptibility testing (AST) is crucial for patient care. Here, the performances of AST methods Vitek-2, Disk Diffusion (DD) and Broth Microdilution (BMD) were compared for the determination of susceptibility of 79 S. pseudintermedius isolates from canine cutaneous infections and one from human pyoderma to oxacillin (OXA), amoxicillin/clavulanate (AMC), cephalothin (CEF), gentamicin (GEN), enrofloxacin (ENR), doxycycline (DOX), clindamycin (CLI), inducible clindamycin resistance (ICR), mupirocin (MUP) and trimethoprim-sulfamethoxazole (SXT). Overall, the agreement of DD and Vitek-2 using veterinary AST-GP80 card with reference BMD was ≥ 90%, suggesting reliable AST performances. While DD generated mainly minor errors and one major error for OXA, Vitek-2 produced one very major error for GEN and it failed in identifying one ICR-positive isolate. Moreover, five bacteria were diagnosed as ICR-positive by Vitek-2 but they showed a non-induction resistance phenotype by manual methods. All S. pseudintermedius were interpreted as susceptible or intermediately susceptible to DOX using CLSI breakpoints for human staphylococci that match the DOX concentration range included in AST-GP80. However, this could lead to inappropriate antimicrobial prescription for S. pseudintermedius infections in companion animals. Considering the clinical and epidemiological importance of S. pseudintermedius , we encourage updating action by the system manufacturer to address AST for this bacterium.

scholarly journals Cefiderocol Antimicrobial Susceptibility Testing against Multidrug-Resistant Gram-Negative Bacilli: a Comparison of Disk Diffusion to Broth Microdilution

2020 ◽  
Vol 59 (1) ◽  
pp. e01649-20 ◽  
Author(s):  
C. Paul Morris ◽  
Yehudit Bergman ◽  
Tsigedera Tekle ◽  
John A. Fissel ◽  
Pranita D. Tamma ◽  
...  
Keyword(s):  
Antimicrobial Susceptibility ◽  
Susceptibility Testing ◽  
Multidrug Resistant ◽  
Antimicrobial Susceptibility Testing ◽  
Disk Diffusion ◽  
Broth Microdilution ◽  
Gram Negative ◽  
Content Type ◽  
Carbapenem Resistant ◽  
Alternative Approach

ABSTRACTAntimicrobial 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 diffusion methods (DD) to broth microdilution (BMD) for AST of Gram-negative bacilli (GNB). Cefiderocol AST was performed on consecutive carbapenem-resistant Enterobacterales (CRE; 58 isolates) and non-glucose-fermenting GNB (50 isolates) by BMD (lyophilized panels; Sensititre; Thermo Fisher) and DD (30 μg; research-use-only [RUO] MASTDISCS and FDA-cleared HardyDisks). Results were interpreted using FDA (prior to 28 September 2020 update), EUCAST, and investigational CLSI breakpoints (BPs). Categorical agreement (CA), minor errors (mE), major errors (ME), and very major errors (VME) were calculated for DD methods. The susceptibilities of all isolates by BMD were 72% (FDA), 75% (EUCAST) and 90% (CLSI). For DD methods, EUCAST BPs demonstrated lower susceptibility at 65% and 66%, compared to 74% and 72% (FDA) and 87% and 89% (CLSI) by HardyDisks and MASTDISCS, respectively. CA ranged from 75% to 90%, with 8 to 25% mE, 0 to 19% ME, and 0 to 20% VME and varied based on disk, GNB, and BPs evaluated. Both DD methods performed poorly for Acinetobacter baumannii complex. There is considerable variability when cefiderocol ASTs are interpreted using CLSI, FDA, and EUCAST breakpoints. DD offers a convenient alternative approach to BMD methods for cefiderocol AST, with the exception of A. baumannii complex isolates.

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