A Reference Broth Microdilution Method for Dalbavancin &lt;em&gt;In Vitro&lt;/em&gt; Susceptibility Testing of Bacteria that Grow Aerobically

Koeth, Laura; DiFranco-Fisher, Jeanna; McCurdy, Sandra P.

doi:10.3791/53028-v

Cited by 8 publications

(7 citation statements)

References 3 publications

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“…The MICs of tetracycline antibiotics (tetracycline, doxycycline, and minocycline) against 17 K. pneumoniae clinical strains and an ATCC strain (K. pneumoniae ATCC 12657) were detected by the broth microdilution method according to the American Committee for Clinical and Laboratory Standards Institute (CLSI) method. 31 In summary, 100 μL of MH broth was dispensed into each well of a 96-well microdrop plate. Antibiotics at concentrations ranging from 0.5 to 512 μg/mL were introduced into the MH medium in the 96-well plates using a multiple dilution technique.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

Subminimum Inhibitory Concentrations Tetracycline Antibiotics Induce Biofilm Formation in Minocycline-Resistant Klebsiella pneumonia by Affecting Bacterial Physical and Chemical Properties and Associated Genes Expression

Guo,

Yang,

Zhou

et al. 2024

ACS Infect. Dis.

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Biofilm formation of Klebsiella pneumoniae can protect bacteria from antibiotics and is difficult to eradicate. Thus, the influence of subinhibitory concentrations of antibiotics on bacteria is becoming increasingly important. Our study showed that subminimum inhibitory concentrations (sub-MICs) of tetracycline antibiotics can increase biofilm formation in minocyclineresistant Klebsiella pneumoniae clinical strains. However, in the bacterial adhesion and invasion experiments, the adhesion and invasion ability decreased and the survival rate of Galleria mellonella increased. Under sub-MICs of tetracycline antibiotics treatment, abnormal stretching of bacteria was observed by scanning electron microscopy. Treatment with sub-MICs of tetracyclines leads to increased surface hydrophobicity and eDNA content and decreased outer membrane permeability. The expression levels of the f imA, luxS, qseB, and qseC genes decreased, the expression level of mrkA increased, and the expression level of acrA was inconsistent under different tetracycline antibiotics treatments. Together, our results suggested that the increase in Klebsiella pneumoniae biofilm formation caused by sub-MICs of tetracycline antibiotics may occur by affecting bacterial physical and chemical properties and associated genes expression.

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Section: ■ Materials and Methodsmentioning

confidence: 99%

Subminimum Inhibitory Concentrations Tetracycline Antibiotics Induce Biofilm Formation in Minocycline-Resistant Klebsiella pneumonia by Affecting Bacterial Physical and Chemical Properties and Associated Genes Expression

Guo,

Yang,

Zhou

et al. 2024

ACS Infect. Dis.

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“…Each experiment lasted 3 to 7 days to obtain the result. The MIC was determined using the broth microdilution method (Koeth et al., 2015). The MIC experiment was performed at or before norvancomycin application.…”

Section: Methodsmentioning

confidence: 99%

Norvancomycin plasma concentration monitoring in hemodialysis patients with end stage kidney disease: A retrospective cohort study

Huo

Hou

et al. 2023

Biopharm & Drug Disp

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Blood concentration monitoring plays an important role in the rational use of norvancomycin. However, the reference interval for the norvancomycin plasma concentration in the treatment of infections in hemodialysis patients with end stage kidney disease is undefined. To determine the safe and effective interval for the norvancomycin plasma trough concentration, 39 patients treated with hemodialysis and norvancomycin were analyzed retrospectively. The norvancomycin plasma concentration before hemodialysis was tested as the trough concentration. The associations of the norvancomycin trough concentration with efficacy and adverse reactions were evaluated. No norvancomycin concentration above 20 μg/mL was detected. The trough concentration, but not the dose, had a significant effect on the anti‐infectious efficacy. Compared with the low norvancomycin trough concentration group (<9.30 μg/mL), the high concentration group (9.30–20.0 μg/mL) had improved efficacy (OR = 15.45, p < 0.01) with similar side effects (OR = 0.5417, p = 0.4069). It is beneficial to maintain the norvancomycin trough concentration at 9.30–20.0 μg/mL to achieve a good anti‐infectious effect in hemodialysis patients with end stage kidney disease. Plasma concentration monitoring provides a data basis for the individual treatment of infections with norvancomycin in hemodialysis patients.

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“…MICs were assessed according to the manufacturer after incubation for 24 h at 35°C (± 2°C). In addition, a broth microdilution (BMD) assay was performed for resistant isolates in Cation-Adjusted Mueller-Hinton Broth (CA-MHB) plus polysorbate 80 (13). The MICs were interpreted according to the EUCAST 2023 guidelines (4).…”

Section: Antimicrobial Susceptibility Testing (Ast)mentioning

confidence: 99%

Unraveling novel Mutation Patterns and Morphological Variations in Two Dalbavancin-resistant MRSA strains in Austria using Whole Genome Sequencing and Transmission Electron Microscopy

Hotz,

Staudacher,

Schefberger

et al. 2024

Preprint

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Purpose: The increasing prevalence of methicillin-resistant Staphylococcus aureus(MRSA) strains resistant to non-beta-lactam antimicrobials poses a significant challenge in treating severe MRSA bloodstream infections. This study explores resistance development and mechanisms in MRSA isolates, especially after the first dalbavancin-resistant MRSA strain in our hospital in 2016. Methods: This study investigated 55 MRSA bloodstream isolates (02/2015–02/2021) from the University Hospital of the Medical University of Vienna, Austria. The MICs of dalbavancin, linezolid, and daptomycin were assessed. Two isolates (16-33 and 19-362) resistant to dalbavancin were analyzed via whole-genome sequencing, with morphology evaluated using transmission electron microscopy (TEM). Results: S.aureusBSI strain 19-362 had two novel missense mutations (p.I515M and p.A606D) in the pbp2 gene. Isolate 16-33 had a 534bp deletion in the DHH domain of GdpP and a SNV in pbp2 (p.G146R). Both strains had mutations in the rpoB gene, but at different positions. TEM revealed significantly thicker cell walls in 16-33 (p < 0.05) compared to 19-362 and dalbavancin-susceptible strains. Over the observed years, a noticeable MIC creep for dalbavancin emerged. None of the MRSA isolates showed resistance to linezolid or daptomycin. Conclusion: Inlight of increasing vancomycin resistance reports, continuous surveillance is essential to comprehend the molecular mechanisms of resistance in alternative MRSA treatment options. Furthermore, based on the observed dalbavancin MIC creep, inclusion of dalbavancin in routine antimicrobial susceptibility testing should be considered.

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A Reference Broth Microdilution Method for Dalbavancin <em>In Vitro</em> Susceptibility Testing of Bacteria that Grow Aerobically

Cited by 8 publications

References 3 publications

Subminimum Inhibitory Concentrations Tetracycline Antibiotics Induce Biofilm Formation in Minocycline-Resistant Klebsiella pneumonia by Affecting Bacterial Physical and Chemical Properties and Associated Genes Expression

Subminimum Inhibitory Concentrations Tetracycline Antibiotics Induce Biofilm Formation in Minocycline-Resistant Klebsiella pneumonia by Affecting Bacterial Physical and Chemical Properties and Associated Genes Expression

Norvancomycin plasma concentration monitoring in hemodialysis patients with end stage kidney disease: A retrospective cohort study

Unraveling novel Mutation Patterns and Morphological Variations in Two Dalbavancin-resistant MRSA strains in Austria using Whole Genome Sequencing and Transmission Electron Microscopy

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