Quality control ranges for testing broth microdilution susceptibility of Flavobacterium columnare and F. psychrophilum to nine antimicrobials

Gieseker, Charles M.; Mayer, Tamara D.; Crosby, Tina C.; Carson, J; Dalsgaard, Inger; Darwish, Ahmed M.; Gaunt, Patricia S.; Gao, Dana X.; Hsu, Hui‐Min; Lin, Tsang Long; Oaks, J. Lindsay; Pyecroft, Melissa; Teitzel, C.; Somsiri, T.; Wu, Ching Ching

doi:10.3354/dao02527

Cited by 12 publications

(10 citation statements)

References 16 publications

(18 reference statements)

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“…Importantly, CLSI () also published quality control criteria based on the acceptable ranges for the reference strains Escherichia coli ATCC 25922 and Aeromonas salmonicida ATCC 33658 for data generated under these standard conditions (Gieseker et al . ).…”

Section: Introductionmentioning

confidence: 97%

“…The latest edition of the CLSI guideline VET04-A2 (CLSI 2014a) published a standard method for microdilution MIC testing of F. psychrophilum. Importantly, CLSI (2014b) also published quality control criteria based on the acceptable ranges for the reference strains Escherichia coli ATCC 25922 and Aeromonas salmonicida ATCC 33658 for data generated under these standard conditions (Gieseker et al 2012).…”

Section: Introductionmentioning

confidence: 99%

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Epidemiological cut‐off values for Flavobacterium psychrophilum MIC data generated by a standard test protocol

Smith

Endris²,

Kronvall

et al. 2014

Journal of Fish Diseases

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Epidemiological cut-off values were developed for application to antibiotic susceptibility data for Flavobacterium psychrophilum generated by standard CLSI test protocols. The MIC values for ten antibiotic agents against Flavobacterium psychrophilum were determined in two laboratories. For five antibiotics, the data sets were of sufficient quality and quantity to allow the setting of valid epidemiological cut-off values. For these agents, the cut-off values, calculated by the application of the statistically based normalized resistance interpretation method, were ≤16 mg L(-1) for erythromycin, ≤2 mg L(-1) for florfenicol, ≤0.025 mg L(-1) for oxolinic acid (OXO), ≤0.125 mg L(-1) for oxytetracycline and ≤20 (1/19) mg L(-1) for trimethoprim/sulphamethoxazole. For ampicillin and amoxicillin, the majority of putative wild-type observations were 'off scale', and therefore, statistically valid cut-off values could not be calculated. For ormetoprim/sulphadimethoxine, the data were excessively diverse and a valid cut-off could not be determined. For flumequine, the putative wild-type data were extremely skewed, and for enrofloxacin, there was inadequate separation in the MIC values for putative wild-type and non-wild-type strains. It is argued that the adoption of OXO as a class representative for the quinolone group would be a valid method of determining susceptibilities to these agents.

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Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Epidemiological cut‐off values for Flavobacterium psychrophilum MIC data generated by a standard test protocol

Smith

Endris²,

Kronvall

et al. 2014

Journal of Fish Diseases

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“…salmonicida ATCC 33658, produced MICs within the approved ranges for all antimicrobials tested except gentamicin, for which no QC ranges exist (Gieseker et al . ). Therefore, the gentamicin data we present should only be considered preliminary as the testing could not be validated with quality control bacteria.…”

Section: Resultsmentioning

confidence: 97%

“…We collected a diverse collection of 120 F. columnare isolates and tested their antimicrobial susceptibility with the standard broth microdilution method against the 10 antimicrobials for which quality control ranges currently exist (Gieseker et al . ; CLSI, ).…”

Section: Introductionmentioning

confidence: 99%

Provisional epidemiological cutoff values for standard broth microdilution susceptibility testing of Flavobacterium columnare

Gieseker

Crosby

Woods

2016

Journal of Fish Diseases

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The gliding aquatic bacterium Flavobacterium columnare causes columnaris disease, a common problem for wild and farmed freshwater fish worldwide. Recently, a broth microdilution method was standardized to test the susceptibility of F. columnare against antimicrobials commonly used in aquaculture. We used this new method to measure the minimal inhibitory concentrations (MICs) of ten antimicrobials against 120 F. columnare isolates. The resulting MIC frequency distributions for each antimicrobial (1 MIC/isolate) were used to estimate epidemiological cut-off values (ECVs) which separate isolates with typical wild-type (WT) susceptibility from isolates with decreased non-wild-type (NWT) susceptibility. We identified 22 NWT isolates with elevated MICs relative to the ECV that covered 99.9% of the MIC distribution against one or more of the antimicrobials: ampicillin, enrofloxacin, erythromycin, florfenicol, flumequine, oxolinic acid or oxytetracycline. Ten of the NWT isolates had decreased susceptibility to a single antimicrobial class, six isolates to two antimicrobial classes and six isolates to three or more antimicrobial classes. The MIC frequency distributions and provisional cut-off values provide data needed to set epidemiological cut-off values to monitor for the development of antimicrobial resistance among F. columnare.

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“…This paper describes similar broth microdilution methods optimized for testing Flavobacterium columnare and F. psychrophilum. These experiments were done to facilitate a recent multilaboratory standardization trial that established QC parameters at the test conditions described in Gieseker et al (2012). Recently, the CLSI updated guideline VET-04 (formerly M49-A) to include methods specific for broth dilution testing of these fastidious gliding bacteria based in part on the experiments described in this paper (CLSI 2014).…”

mentioning

confidence: 99%

Development of Similar Broth Microdilution Methods to Determine the Antimicrobial Susceptibility of Flavobacterium columnare and F. psychrophilum

et al. 2016

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Flavobacterium columnare and F. psychrophilum are major fish pathogens that cause diseases that may require antimicrobial therapy. Choice of appropriate treatment is dependent upon determining the antimicrobial susceptibility of isolates. Therefore we optimized methods for broth microdilution testing of F. columnare and F. psychrophilum to facilitate standardizing an antimicrobial susceptibility test. We developed adaptations to make reproducible broth inoculums and confirmed the proper incubation time and media composition. We tested the stability of potential quality-control bacteria and compared test results between different operators. Log phase occurred at 48 h for F. columnare and 72-96 h for F. psychrophilum, confirming the test should be incubated at 28°C for approximately 48 h and at 18°C for approximately 96 h, respectively. The most consistent susceptibility results were achieved with plain, 4-g/L, dilute Mueller-Hinton broth supplemented with dilute calcium and magnesium. Supplementing the broth with horse serum did not improve growth. The quality-control strains, Escherichia coli ATCC 25922 and Aeromonas salmonicida subsp. salmonicida ATCC 33658, yielded stable minimal inhibitory concentrations (MIC) against all seven antimicrobials tested after 30 passes at 28°C and 15 passes at 18°C. In comparison tests, most MICs of the isolates agreed 100% within one drug dilution for ampicillin, florfenicol, and oxytetracycline. The agreement was lower with the ormetoprim-sulfdimethoxine combination, but there was at least 75% agreement for all but one isolate. These experiments have provided methods to help standardize antimicrobial susceptibility testing of these nutritionally fastidious aquatic bacteria. Received June 24, 2015; accepted October 2, 2015.

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Quality control ranges for testing broth microdilution susceptibility of Flavobacterium columnare and F. psychrophilum to nine antimicrobials

Cited by 12 publications

References 16 publications

Epidemiological cut‐off values for Flavobacterium psychrophilum MIC data generated by a standard test protocol

Epidemiological cut‐off values for Flavobacterium psychrophilum MIC data generated by a standard test protocol

Provisional epidemiological cutoff values for standard broth microdilution susceptibility testing of Flavobacterium columnare

Development of Similar Broth Microdilution Methods to Determine the Antimicrobial Susceptibility of Flavobacterium columnare and F. psychrophilum

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