Related Experiment Video
Updated: Jun 11, 2026
Demonstrating a Multi-drug Resistant Mycobacterium tuberculosis Amplification Microarray
Published on: April 25, 2014
Multicenter study for defining the breakpoint for rifampin resistance in Neisseria meningitidis by rpoB sequencing
Muhamed-Kheir Taha1, Sara Thulin Hedberg, Marek Szatanik
1Institut Pasteur, National Reference Centre for Meningococci, 28 Rue du Dr. Roux, Paris, France. mktaha@pasteur.fr
Abstract:
Identification of clinical isolates of Neisseria meningitidis that are resistant to rifampin is important to avoid prophylaxis failure in contacts of patients, but it is hindered by the absence of a breakpoint for resistance, despite many efforts toward standardization. We examined a large number (n = 392) of clinical meningococcal isolates, spanning 25 years (1984 to 2009), that were collected in 11 European countries, Argentina, and the Central African Republic. The collection comprises all clinical isolates with MICs of > or = 0.25 mg/liter (n = 161) received by the national reference laboratories for meningococci in the participating countries. Representative isolates displaying rifampin MICs of < 0.25 mg/liter were also examined (n = 231). Typing of isolates was performed, and a 660-bp DNA fragment of the rpoB gene was sequenced. Sequences differing by at least one nucleotide were defined as unique rpoB alleles. The geometric mean of the MICs was calculated for isolates displaying the same allele. The clinical isolates displaying rifampin MICs of > 1 mg/liter possessed rpoB alleles with nonsynonymous mutations at four critical amino acid residues, D542, H552, S548, and S557, that were absent in the alleles found in all isolates with MICs of < or = 1 mg/liter. Rifampin-susceptible isolates could be defined as those with MICs of < or = 1 mg/liter. The rpoB allele sequence and isolate data have been incorporated into the PubMLST Neisseria database (http://pubmlst.org/neisseria/). The rifampin-resistant isolates belonged to diverse genetic lineages and were associated with lower levels of bacteremia and inflammatory cytokines in mice. This biological cost may explain the lack of clonal expansion of these isolates.
Insights
Identifying Neisseria meningitidis rifampin resistance is crucial to prevent prophylaxis failure. Mutations in the rpoB gene at specific amino acid residues define rifampin resistance in meningococcal isolates.
Area of Science:
- Microbiology
- Genetics
- Epidemiology
Background:
- Accurate identification of Neisseria meningitidis rifampin resistance is vital for effective prophylaxis in close contacts of infected individuals.
- Standardization of rifampin resistance breakpoints for Neisseria meningitidis has been challenging, hindering accurate detection.
- Previous efforts to establish resistance criteria have been hampered by a lack of standardized breakpoints.
Purpose of the Study:
- To identify specific genetic markers associated with rifampin resistance in clinical Neisseria meningitidis isolates.
- To establish a reliable criterion for defining rifampin resistance in Neisseria meningitidis based on genetic analysis.
- To investigate the genetic diversity and potential biological cost associated with rifampin resistance.
Main Methods:
- Analysis of 392 clinical Neisseria meningitidis isolates collected globally over 25 years.
- Sequencing of a 660-bp DNA fragment of the rpoB gene to identify unique alleles.
- Determination of rifampin Minimum Inhibitory Concentrations (MICs) for all isolates and correlation with rpoB alleles.
Main Results:
- Clinical isolates with rifampin MICs > 1 mg/L exhibited nonsynonymous mutations in the rpoB gene at critical residues D542, H552, S548, and S557.
- Isolates with MICs ≤ 1 mg/L lacked these specific rpoB mutations, suggesting MIC ≤ 1 mg/L as a criterion for susceptibility.
- Rifampin-resistant isolates showed reduced bacteremia and inflammatory cytokine levels in murine models, indicating a potential biological cost.
Conclusions:
- Nonsynonymous mutations at rpoB amino acid residues D542, H552, S548, and S557 reliably identify rifampin-resistant Neisseria meningitidis.
- A rifampin MIC of ≤ 1 mg/L can be used to define susceptible Neisseria meningitidis isolates.
- The identified genetic mutations and associated biological cost provide a basis for improved diagnostics and understanding of resistance dynamics.
Related Concept Videos
01:25Clinical Significance of Antibiotic Resistance
01:25Mechanism of Antibiotic Resistance in MRSA
01:25Rapid Identification of Pathogens