Multicenter study for defining the breakpoint for rifampin resistance in Neisseria meningitidis by rpoB sequencing.
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.
Taha
Muhamed-Kheir
MK
Institut Pasteur, National Reference Centre for Meningococci, 28 Rue du Dr. Roux, Paris, France. mktaha@pasteur.fr
Hedberg
Sara Thulin
ST
Szatanik
Marek
M
Hong
Eva
E
Ruckly
Corinne
C
Abad
Raquel
R
Bertrand
Sophie
S
Carion
Francoise
F
Claus
Heike
H
Corso
Alejandra
A
Enríquez
Rocío
R
Heuberger
Sigrid
S
Hryniewicz
Waleria
W
Jolley
Keith A
KA
Kriz
Paula
P
Mollerach
Marta
M
Musilek
Martin
M
Neri
Arianna
A
Olcén
Per
P
Pana
Marina
M
Skoczynska
Anna
A
Sorhouet Pereira
Cecilia
C
Stefanelli
Paola
P
Tzanakaki
Georgina
G
Unemo
Magnus
M
Vázquez
Julio A
JA
Vogel
Ulrich
U
Wasko
Izabela
I
D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics*; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D005260:Female; D051379:Mice; D008807:Mice, Inbred BALB C; D008822:Mice, Transgenic; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D009345:Neisseria meningitidis / Q000187:drug effects / Q000235:genetics*; D010802:Phylogeny; D012293:Rifampin / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D012293:Rifampin