Genomewide screening for novel genetic variations associated with ciprofloxacin resistance in Bacillus anthracis.
Fluoroquinolone (FQ) resistance of Bacillus anthracis is a serious concern in the fields of biodefense and bioterrorism since FQs are very effective antibiotics and are recommended as first-line treatment against this lethal bacterium. In this study, we obtained 2 strains of B. anthracis showing resistance or intermediate resistance to ciprofloxacin (CIP) by a stepwise selection procedure with increasing CIP concentrations. Fifteen genetic variations were identified between the parental and CIP-resistant strains by next-generation sequencing. Nonsynonymous mutations in the quinolone resistance-determining region (QRDR) of type II DNA topoisomerase were identified in the resistant strain but not in the intermediate-resistant strain. The GBAA0834 (TetR-type transcriptional regulator) locus was also revealed to be a novel "mutation hot spot" that leads to the increased expression of multidrug efflux systems for CIP resistance. As an initial step of CIP resistance in B. anthracis, such disruptive mutations of GBAA0834 appear to be more easily acquired than those in an essential gene, such as that encoding type II DNA topoisomerase. Such an intermediate-resistant phenotype could increase a cell population under CIP-selective pressure and might promote the emergence of highly resistant isolates. Our findings reveal, in addition to QRDR, crucial genetic targets for the investigation of intermediate resistance of B. anthracis to FQs.
Serizawa
Masakuni
M
Laboratory of Bacterial Genomics, Pathogen Genomics Center, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan.
Sekizuka
Tsuyoshi
T
Okutani
Akiko
A
Banno
Satomi
S
Sata
Tetsutaro
T
Inoue
Satoshi
S
Kuroda
Makoto
M
D001408:Bacillus anthracis / Q000187:drug effects* / Q000235:genetics*; D002939:Ciprofloxacin / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D014644:Genetic Variation; D016680:Genome, Bacterial / Q000235:genetics*; D055106:Genome-Wide Association Study; D008969:Molecular Sequence Data; D009154:Mutation; D020133:Reverse Transcriptase Polymerase Chain Reaction
D002939:Ciprofloxacin
J Antimicrob Chemother. 2003 May;51(5):1109-17
12697644
JAMA. 2002 May 1;287(17):2236-52
11980524
N Engl J Med. 2001 Nov 29;345(22):1621-6
11704686
Antimicrob Agents Chemother. 2003 Jul;47(7):2362-5
12821500
Nature. 2008 Nov 6;456(7218):60-5
18987735
Science. 2002 Jun 14;296(5575):2028-33
12004073
Antimicrob Agents Chemother. 1994 Sep;38(9):2014-23
7811012
FEMS Microbiol Rev. 2005 Apr;29(2):303-29
15808746
Nature. 2008 Nov 6;456(7218):66-72
18987736
J Antimicrob Chemother. 2004 Jul;54(1):90-4
15190035
Antimicrob Agents Chemother. 1994 Jun;38(6):1345-55
8092836
Trends Microbiol. 1999 May;7(5):191-5
10354593
Annu Rev Microbiol. 2001;55:647-71
11544370
Appl Environ Microbiol. 2006 Aug;72(8):5304-10
16885280
J Bacteriol. 1990 Dec;172(12):7260-2
2174869
Microbiol Mol Biol Rev. 2005 Jun;69(2):326-56
15944459
Curr Opin Microbiol. 2001 Oct;4(5):509-14
11587925
Proc Natl Acad Sci U S A. 2009 Jul 28;106(30):12412-7
19617543
PLoS Genet. 2008 Aug 01;4(8):e1000139
18670626
Antimicrob Agents Chemother. 1999 Oct;43(10):2404-8
10508015
Nature. 2008 Nov 6;456(7218):53-9
18987734
Microbiol Mol Biol Rev. 2002 Dec;66(4):671-701, table of contents
12456787
Genome Res. 2008 Nov;18(11):1851-8
18714091
Antimicrob Agents Chemother. 2004 Aug;48(8):3024-7
15273116
Bioinformatics. 2009 Jun 15;25(12):1554-5
19369497
Nat Struct Biol. 2000 Mar;7(3):215-9
10700280
Eur J Clin Microbiol Infect Dis. 2002 Sep;21(9):647-59
12373497