This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Jacoby, G. A.
Right arrow Articles by Hooper, D. C.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Jacoby, G. A.
Right arrow Articles by Hooper, D. C.

 Previous Article  |  Next Article 

Antimicrobial Agents and Chemotherapy, April 2006, p. 1178-1182, Vol. 50, No. 4
0066-4804/06/$08.00+0     doi:10.1128/AAC.50.4.1178-1182.2006
Copyright © 2006, American Society for Microbiology. All Rights Reserved.

qnrB, Another Plasmid-Mediated Gene for Quinolone Resistance

George A. Jacoby,1* Kelley E. Walsh,1 Debra M. Mills,1 Victoria J. Walker,1 Herin Oh,2 Ari Robicsek,2 and David C. Hooper2

Lahey Clinic, Burlington,1 Massachusetts General Hospital, Boston, Massachusetts2

Received 17 November 2005/ Returned for modification 12 December 2005/ Accepted 12 January 2006


arrow
ABSTRACT
 
A novel plasmid-mediated quinolone resistance gene, qnrB, has been discovered in a plasmid encoding the CTX-M-15 ß-lactamase from a Klebsiella pneumoniae strain isolated in South India. It has less than 40% amino acid identity with the original qnr (now qnrA) gene or with the recently described qnrS but, like them, codes for a protein belonging to the pentapeptide repeat family. Strains with qnrB demonstrated low-level resistance to all quinolones tested. The gene has been cloned in an expression vector attaching a polyhistidine tag, which facilitated purification to ≥95% homogeneity. As little as 5 pM of QnrB-His6 protected purified DNA gyrase against inhibition by 2 µg/ml (6 µM) ciprofloxacin. With a PCR assay qnrB has been detected in Citrobacter koseri, Enterobacter cloacae, and Escherichia coli isolates from the United States, linked to SHV-12 ß-lactamase and coding for a product differing in five amino acids from the Indian (now QnrB1) variety. The qnrB gene has been found near Orf1005 in some, but not all, plasmids and in association with open reading frames matching known chromosomal genes, suggesting that it too was acquired by plasmids from an as-yet-unknown bacterial source.


arrow
INTRODUCTION
 
The first plasmid-mediated quinolone resistance gene (qnr) was discovered in a Klebsiella pneumoniae isolate from Birmingham, Alabama, collected in 1994 (10). It occurred in a multiresistance plasmid, pMG252, in an integron-like structure near Orf513 (17). Qnr, the gene product, is a member of the pentapeptide repeat family of proteins and has been shown to block the action of ciprofloxacin on purified DNA gyrase and topoisomerase IV (17, 19). In Escherichia coli pMG252 determines low-level quinolone resistance but facilitates the selection of higher-level resistance mutations (10). qnr plasmids have been found in clinical isolates of Citrobacter freundii, Enterobacter spp., E. coli, K. pneumoniae, Providencia stuartii, and Salmonella spp. from the United States, Europe, and the Near and Far East (1, 13). Another qnr gene, qnrS, has also recently been found in a plasmid from a strain of Shigella flexneri isolated in Japan (2).

While investigating strains of K. pneumoniae from India, some of which contained qnr, it was realized that several could transfer low-level quinolone resistance but were negative by PCR for qnr. The new plasmid-mediated quinolone resistance gene has been termed qnrB, and the original gene is now designated qnrA. qnrB has been cloned and sequenced. Purified QnrB protects DNA gyrase from quinolone action like QnrA does. A PCR assay for qnrB indicates that it is as common as qnrA in samples from the United States and has greater amino acid variability.

(The results of this study were presented in part at the 44th Interscience Conference on Antimicrobial Agents and Chemotherapy, 30 October to 2 November 2004, Washington, D.C.)


arrow
MATERIALS AND METHODS
 
Strains, plasmids, and growth conditions. K. pneumoniae strains 17, 19, 21, 24, and 25 were isolated from blood, a catheter tip, pus, and sputum in 2002 and 2003 at Coimbatore in South India. Citrobacter koseri 3699-1 was isolated at Long Beach, CA, in 2000. Enterobacter cloacae 3668 came from Philadelphia, PA, in 2000-2001 (9). E. cloacae 78149 and Escherichia coli EC-35 were acquired in 1996 from St. Louis, MO. Matings were performed with E. coli J53 Azir (met pro; azide-resistant) as a recipient (6). E. coli TOP10 (Invitrogen, Carlsbad, CA) was used in cloning. Strains were routinely grown in Luria-Bertani broth. Culture plates contained tryptic soy agar (TSA) or Mueller-Hinton agar (Becton, Dickinson and Co., Sparks, MD). Selective media contained ampicillin (100 µg/ml), cefotaxime (10 µg/ml), chloramphenicol (25 µg/ml), ciprofloxacin (0.015 µg/ml), kanamycin (25 µg/ml), or nalidixic acid (12 µg/ml) as required.

Susceptibility testing. Disk and agar dilution susceptibility testing was performed as described in CLSI (formerly NCCLS) publications, using Mueller-Hinton agar and 16 to 20 h of incubation at 37°C (11, 12).

Cloning and nucleotide sequence analysis. Plasmid DNA was isolated from an E. coli J53 derivative by using the Large-Construct kit (QIAGEN, Valencia, CA), digested with one of several endonucleases, ligated to similarly restricted phagemid pBC SK (Stratagene), and introduced into E. coli TOP10 with selection on TSA plates containing chloramphenicol and nalidixic acid. Using the GPS-1 genome priming system (NE Biolabs, Ipswich, MA), a kanamycin resistance transposon was inserted to inactivate the quinolone resistance gene and allow sequencing using primerN and primerS from the transposon ends. Cycle sequencing was carried out with an ABI Prism 3100 genetic analyzer (Tufts University Core Facility) and was continued by primer walking on both DNA strands. For sequence comparisons, the NCBI BLAST program and facilities of the TIGR Comprehensive Microbial Resource (www.tigr.org) were utilized.

Overexpression and purification of QnrB. The qnrB1 gene from pMG298 was cloned into expression vector pQE-60 (QIAGEN) at its NcoI and BamHI sites. An internal NcoI site was first removed from qnrB1 by using the QuikChange site-directed mutagenesis kit (Stratagene, La Jolla, CA) with primers 5'-GTGATTTATCGATGGCGGATTTTCGC and 5'-GCGAAAATCCGCCATCGATAAATCAC, which cause no change in the amino acid sequence. The gene was then amplified by PCR using primers 5'-GGCCATGGCGCCATTACTGTATAAA and 5'-GCGCGGATCCACCAATCACCGCGATGCC and ligated after digestion with NcoI and BamHI into pQE-60. In the process, the amino acid following the initial methionine was changed from threonine to alanine and a tag of six histidines was added to the C terminus of the protein. Proper construction was confirmed by sequencing, and the pQE60-QnrB1 plasmid was transformed into E. coli M15(pREP4) (QIAGEN) to place expression of qnrB1 under the control of induction by isopropyl-1-thio-ß-D-galactopyranoside (IPTG).

E. coli M15 (pREP4)(pQE-60-QnrB1) was grown in LB medium with 100 µg/ml ampicillin and 25 µg/ml kanamycin until the cell density reached an optical density at 600 nm of 0.6 to 0.8, induced with IPTG at a final concentration of 1 mM, and allowed 4 h of further growth until being harvested by centrifugation. The pellet was suspended in 20 mM Tris-HCl (pH 7.5), 10% glycerol, 150 mM NaCl and lysed with 0.02% lysozyme and 1x EDTA-free protease inhibitor mix (Roche Diagnostics, Mannheim, Germany) on ice for 0.5 to 2 h. The lysate was centrifuged at 25,000 x g for 90 min at 4°C. The supernatant containing the soluble protein was filtered through a 0.2-µm membrane with a Nalgene filter unit (Nalgene, Rochester, NY) and loaded onto a preequilibrated HiTrapChelating HP column (Amersham Biosciences, Piscataway, NJ), and the histidine-tagged protein was eluted with increasing concentrations of imidazole (50 to 300 mM) and collected in 1-ml fractions. The eluted fractions were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis using precast 12% Ready Tris-HCl gels (Bio-Rad, Hercules, CA). Fractions containing a single protein band of 25 kDa were dialyzed against 50 mM Tris-HCl (pH 7.5), 5 mM dithiothreitol, 150 mM NaCl, 10% glycerol overnight at 4°C with several buffer changes. Protein concentrations were determined using the Bradford assay (Bio-Rad).

Gyrase supercoiling assay. DNA supercoiling assays were performed as described previously, using DNA gyrase reconstituted from cloned E. coli GyrA and GyrB subunits (18) and relaxed pBR322 plasmid DNA (Topogen Inc., Port Orange, FL).

ß-Lactamase characterization. The presence of an extended-spectrum ß-lactamase (ESBL) was suspected from cefotaxime and ceftazidime resistance and confirmed by repeat testing in the presence of clavulanic acid (11). Transmissibility of resistance was tested by mating clinical isolates with E. coli J53 Azir with selection on TSA agar plates containing 10 µg/ml cefotaxime and 200 µg/ml sodium azide. ß-Lactamase isoelectric focusing was carried out using the PhastSystem (Amersham Biosciences, Piscataway, NJ) as described by Huovinen (4). bla genes were amplified using primers 5'-TTTCCCCATTCCGTTTCCGC and 5'-TTCGTATCTTCCAGAATAAG for blaCTX-M-15 amplification and previously described primers S1 and S2 for blaSHV amplification (20). The amplified genes were sequenced using the same primers and additional primers designed from the known bla gene sequence.

PCR conditions. Detection of qnrA utilized primers QP1 and QP2 with PCR conditions as previously described (5). For qnrB, primers FQ1 (5'-ATGACGCCATTACTGTATAA) and FQ2 (5'-GATCGCAATGTGTGAAGTTT) were used. PCR conditions were 94°C for 45 s, 53°C for 45 s, and 72°C for 1 min for 32 cycles. The presence of Orf513 was tested with primers 5'-AAGGAACGCCACGGCGAGTCAA and 5'-TGCAAAGACGCCGTGGAAGC, and the presence of Orf1005 was evaluated with primers 5'-CTTGGTATTCGAAGCTGGTC and 5'-CTACCGTTTGCAACAGTAAG.

Nucleotide sequence accession numbers. The qnrB1 and qnrB2 sequences have been submitted to GenBank with accession numbers DQ351241 and DQ351242.


arrow
RESULTS
 
Discovery of qnrB. The K. pneumoniae strains from India were originally studied to determine the basis of their ESBL phenotype. Transconjugants of strains 17, 19, 24, and 25, selected for cefotaxime resistance, were noted to have low-level quinolone resistance, but when tested by PCR with primers QP1 and QP2, only K. pneumoniae strains 19 and 24 were positive for the known qnr gene.

Accordingly, DNA of plasmid pMG298 from strain 17 was digested with PstI endonuclease and ligated into vector pBC SK (determining chloramphenicol resistance), selecting for simultaneous resistance to ciprofloxacin and chloramphenicol. A recombinant plasmid containing a 15.3-kb insert was obtained. Quinolone resistance was also expressed from pBC SK containing a 4.8-kb BamHI fragment from plasmid pMG299 originating in strain 24 and from a 5.9-kb PstI fragment from plasmid pMG300 transferred from strain 25.

To facilitate DNA sequencing, a Tn7-based transposon carrying a kanamycin resistance gene was inserted into the recombinant plasmids, and colonies were screened for loss of nalidixic acid resistance. Using primers that matched sequence at the ends of the inserted transposon, sequencing was initiated and continued by primer walking with the original unmodified recombinant plasmid. A new quinolone resistance gene, qnrB1, was discovered. It had 49.5% nucleotide identity and 39.5% amino acid identity with qnrA and 49.3% nucleotide identity and 37.4% amino acid identity with qnrS (Fig. 1) and had the potential to code for a 226-amino-acid protein, which belonged to the pentapeptide repeat family.


Figure 1
View larger version (37K):
[in this window]
[in a new window]
  		FIG. 1. CLUSTAL W alignment of QnrA, QnrB1, QnrB2, and QnrS.

Distribution of qnrB. Using PCR with primers derived from the qnrB1 sequence, the gene was found also in K. pneumoniae strains 21, 24, and 25 from southern India, but the plasmids involved differed in resistance properties (Table 1). Plasmid pMG299 from strain 24, like plasmid pMG298 from strain 17, carried blaCTX-M-15, but the qnrB1 plasmid pMG300 from strain 25 encoded SHV-12 and had no CTX-M gene by PCR. The blaSHV-12 gene was also present in strain 21, but neither ß-lactam nor other antibiotic resistances could be transferred from it by conjugation, implying the presence of a Tra– plasmid.


View this table:
[in this window]
[in a new window]
  		TABLE 1. Properties of QnrB plasmids

Over 100 other plasmid-carrying strains were screened for qnrB. A strain with another CTX-M-15 plasmid was negative, but 4 of about 20 independently derived plasmids encoding SHV-12 were positive, including plasmids found in C. koseri, E. cloacae, and E. coli (Table 1). All had identical sequences which differed from that of qnrB1 by 26 of 680 nucleotides, including an additional nucleotide prior to a second potential ATG start codon at position 36. The extra nucleotide would cause a frameshift if translation began at the first site, so that the qnrB2 gene codes for a 215-amino-acid protein that in addition differs from QnrB1 in 5 amino acids (Fig. 1). The qnrB2 plasmids all encode SHV-12 but differ in other associated resistances (Table 1). Attempts to clone qnrB2 with BamHI or PstI failed, but the gene was cloned into pBC SK as a 2.4-kb EcoRI fragment.

Genetic environment of qnrB. The immediate genetic environments of qnrB1 in plasmids pMG298, pMG299, and pMG300 were similar (Fig. 2). qnrB1 was found downstream from Orf1005, which encodes a putative transposase and is bracketed by imperfect 83-bp inverted repeat segments (16). In pMG298 a tnpA gene was found downstream from Orf1005, but this gene was absent in pMG300. Between Orf1005 and qnrB1 was a 383-bp open reading frame, Orf1, which is >70% identical to a truncated pspF gene coding for the transcriptional activator of the stress-inducible psp operon (7). Orf1 contains an EcoRI site, and a shorter segment of Orf1 was found upstream from the qnrB2 gene, which was cloned on an EcoRI fragment (Fig. 2). Downstream from qnrB2 was an open reading frame (Orf2), with >60% identity to hypothetical proteins of several gram-negative species, and Orf3, with 83% identity to the sapA gene, which encodes a peptide transport periplasmic protein in gram-negative bacteria. By a PCR assay Orf1005 was present in K. pneumoniae strains 17, 24, and 25 but not in any of the strains containing qnrB2. Orf512 was not detected in any of the strains.


Figure 2
View larger version (19K):
[in this window]
[in a new window]
  		FIG. 2. Maps of cloned qnrB genes. The sizes of the cloned fragments vary, as indicated by the 1-kb reference bars. Orf1 resembles pspF, Orf2 is related to genes of unknown function in various gram-negative bacteria, and Orf3 resembles sapA.

Effect of QnrB on quinolone susceptibility. Like QnrA, QnrB provided low-level resistance to all quinolones tested (Table 2).


View this table:
[in this window]
[in a new window]
  		TABLE 2. Susceptibility of E. coli J53 transconjugants to various quinolones

Effect of QnrB on quinolone inhibition of gyrase. To investigate the mechanism of quinolone protection, qnrB was cloned into an expression vector that attached a C-terminal polyhistidine tag, which facilitated purification of QnrB-His6 protein by Ni affinity chromatography. His-tagged QnrB appeared to be ≥95% homogenous by gel assay.

QnrB-His6 demonstrated a concentration-dependent protection of purified gyrase from ciprofloxacin inhibition of DNA supercoiling (Fig. 3). With 2 µg/ml (6 µM) ciprofloxacin, the concentration of QnrB-His6 required for half protection was about 0.5 nM, and a protective effect was seen with as little as 5 pM. The highest concentration of QnrB-His6 tested (25 µM) inhibited gyrase-mediated DNA supercoiling, but inhibition was not seen with 5 µM QnrB-His6, a concentration still 750 times higher than that of DNA gyrase (Fig. 3, compare lanes 4 and 5).


Figure 3
View larger version (44K):
[in this window]
[in a new window]
  		FIG. 3. QnrB1 protection of DNA gyrase from ciprofloxacin inhibition of supercoiling. Reaction mixtures of 30 µl were analyzed by agarose gel electrophoresis. Reaction mixtures contained 0.2 µg relaxed pBR322 DNA (lanes 1 to 14), 6.7 nM gyrase (lanes 2 to 14), 2 µg/ml ciprofloxacin (lanes 3 to 14), and QnrB-His6 fusion protein at 25 µM (lane 4), 5 µM (lane 5), 2.5 µM (lane 6), 0.5 µM (lane 7), 50 nM (lane 8), 5 nM (lane 9), 0.5 nM (lane 10), 50 pM (lane 11), 5 pM (lane 12), or 0.5 pM (lane 13).


arrow
DISCUSSION
 
QnrB, like QnrA and QnrS (2), provides low-level resistance to quinolones and belongs to the pentapeptide repeat family of proteins, one member of which has recently been shown to have a DNA-like structure which would allow it to mimic DNA as a substrate for DNA gyrase (3). For a protein in which overall structure is important rather than catalytic activity, considerable amino acid variability may be permissible. Thus, QnrB and QnrA have only 39.5% of their amino acids in common, while QnrB and QnrS share 37.4%, but all are pentapeptide repeat proteins with two domains joined by a glycine residue (17).

Purified QnrB, like QnrA, protected DNA gyrase from quinolone action. It seems to be even more potent than QnrA in blocking the action of ciprofloxacin (17). At a concentration almost 4,000 times that of DNA gyrase, QnrB inhibited the enzyme, but this effect disappeared at a fivefold lower concentration of QnrB. Thus, in contrast to MfpA, another pentapeptide repeat protein that blocks ciprofloxacin action (3), QnrB did not inhibit gyrase-mediated DNA supercoiling over a wide range of quinolone-protective concentrations. Accordingly, models of Qnr action that do not require direct gyrase inhibition must be considered.

A close relative and likely progenitor of QnrA, differing in only 1 to 2% amino acids, has recently been found in the commensal water organism Shewanella algae (15). The origin of QnrB is not yet known, since the closest relative currently disclosed by a BLAST search is a hypothetical protein from Photobacterium profundum with only 44.5% amino acid identity. The qnrA gene has been found in plasmids with a variety of other resistance determinants but always as part of a sul1-type integron (13). qnrB1 is located near a putative transposase, Orf1005, in plasmids pMG298 and pMG299, but Orf1005 was absent from QnrB2 plasmids from the United States. The linkage of qnrB to Orf1, Orf2, and Orf3, which resemble known chromosomal genes, suggests that all were acquired from a chromosomal source. The homologues of Orf1 and Orf3 are adjacent to each other on the P. profundum chromosome, but the homologues of qnrB and Orf2 occupy separate and distant locations. The mechanism of qnrB acquisition, like that of qnrS, remains to be elucidated.

In both India and the United States qnrB has been found on plasmids also encoding ESBLs: CTX-M-15 and SHV-12 in India and SHV-12 in the United States. The frequent association of quinolone resistance with ESBL production has been noted in several studies (8, 14). The presence of qnr and blaESBL genes on the same plasmid is one of several possible explanations for this association.

qnrB2 has been found on plasmids collected in 1996, and the association of qnrB with SHV-12 on plasmids found in both India and the United States suggests that this resistance mechanism has been present long enough to disseminate widely. Preliminary surveys indicate that in ceftazidime-resistant Enterobacter and Klebsiella isolates from the United States qnrB is as common as qnrA (Robicsek et al., unpublished observations). It would not be surprising if even more members of the qnr family were discovered.


arrow
ACKNOWLEDGMENTS
 
This study was supported in part by grants AI43312 (to G.A.J.) and AI57576 (to D.C.H.) from the National Institutes of Health, U.S. Public Health Service.


arrow
FOOTNOTES
 
* Corresponding author. Mailing address: Lahey Clinic, 41 Mall Road, Burlington, MA 01805. Phone: (781) 744-2928. Fax: (781) 744-5486. E-mail: george.a.jacoby{at}lahey.org. Back


arrow
REFERENCES
 
    1
  1. Cheung, T. K., Y. W. Chu, M. Y. Chu, C. H. Ma, R. W. Yung, and K. M. Kam. 2005. Plasmid-mediated resistance to ciprofloxacin and cefotaxime in clinical isolates of Salmonella enterica serotype Enteritidis in Hong Kong. J. Antimicrob. Chemother. 56:586-589.[Abstract/Free Full Text]
    2. 2
  2. Hata, M., M. Suzuki, M. Matsumoto, M. Takahashi, K. Sato, S. Ibe, and K. Sakae. 2005. Cloning of a novel gene for quinolone resistance from a transferable plasmid in Shigella flexneri 2b. Antimicrob. Agents Chemother. 49:801-803.[Abstract/Free Full Text]
    3. 3
  3. Hegde, S. S., M. W. Vetting, S. L. Roderick, L. A. Mitchenall, A. Maxwell, H. E. Takiff, and J. S. Blanchard. 2005. A fluoroquinolone resistance protein from Mycobacterium tuberculosis that mimics DNA. Science 308:1480-1483.[Abstract/Free Full Text]
    4. 4
  4. Huovinen, S. 1988. Rapid isoelectric focusing of plasmid-mediated ß-lactamases with Pharmacia PhastSystem. Antimicrob. Agents Chemother. 32:1730-1732.[Abstract/Free Full Text]
    5. 5
  5. Jacoby, G. A., N. Chow, and K. B. Waites. 2003. Prevalence of plasmid-mediated quinolone resistance. Antimicrob. Agents Chemother. 47:559-562.[Abstract/Free Full Text]
    6. 6
  6. Jacoby, G. A., and P. Han. 1996. Detection of extended-spectrum ß-lactamases in clinical isolates of Klebsiella pneumoniae and Escherichia coli. J. Clin. Microbiol. 34:908-911.[Abstract]
    7. 7
  7. Jovanovic, G., L. Weiner, and P. Model. 1996. Identification, nucleotide sequence, and characterization of PspF, the transcriptional activator of the Escherichia coli stress-induced psp operon. J. Bacteriol. 178:1936-1945.[Abstract/Free Full Text]
    8. 8
  8. Lautenbach, E., B. L. Strom, W. B. Bilker, J. B. Patel, P. H. Edelstein, and N. O. Fishman. 2001. Epidemiological investigation of fluoroquinolone resistance in infections due to extended-spectrum ß-lactamase-producing Escherichia coli and Klebsiella pneumoniae. Clin. Infect. Dis. 33:1288-1294.[CrossRef][Medline]
    9. 9
  9. Levison, M. E., Y. V. Mailapur, S. K. Pradham, G. A. Jacoby, P. D. Adams, C. L. Emery, P. L. May, and P. G. Pitsakis. 2002. Regional occurrence of plasmid-mediated SHV-7, an extended-spectrum ß-lactamase, in Enterobacter cloacae in Philadelphia teaching hospitals. Clin. Infect. Dis. 35:1551-1554.[CrossRef][Medline]
    10. 10
  10. Martínez-Martínez, L., A. Pascual, and G. A. Jacoby. 1998. Quinolone resistance from a transferable plasmid. Lancet 351:797-799.[CrossRef][Medline]
    11. 11
  11. NCCLS. 2003. Methods for dilution antimicrobial susceptibility tests for bacteria that grow aerobically, 6th ed. Approved standard M7-A6. National Committee for Clinical Laboratory Standards, Wayne, Pa.
    12. 12
  12. NCCLS. 2003. Performance standards for antimicrobial disk susceptibility tests, 8th ed. Approved standard M2-A8. National Committee for Clinical Laboratory Standards, Wayne, Pa.
    13. 13
  13. Nordmann, P., and L. Poirel. 2005. Emergence of plasmid-mediated resistance to quinolones in Enterobacteriaceae. J. Antimicrob. Chemother. 56:463-469.[Abstract/Free Full Text]
    14. 14
  14. Paterson, D. L., L. Mulazimoglu, J. M. Casellas, W. C. Ko, H. Goossens, A. Von Gottberg, S. Mohapatra, G. M. Trenholme, K. P. Klugman, J. G. McCormack, and V. L. Yu. 2000. Epidemiology of ciprofloxacin resistance and its relationship to extended-spectrum ß-lactamase production in Klebsiella pneumoniae isolates causing bacteremia. Clin. Infect. Dis. 30:473-478.[CrossRef][Medline]
    15. 15
  15. Poirel, L., J. M. Rodriguez-Martinez, H. Mammeri, A. Liard, and P. Nordmann. 2005. Origin of plasmid-mediated quinolone resistance determinant QnrA. Antimicrob. Agents Chemother. 49:3523-3525.[Abstract/Free Full Text]
    16. 16
  16. Sabaté, M., F. Navarro, E. Miro, S. Campoy, B. Mirelis, J. Barbe, and G. Prats. 2002. Novel complex sul1-type integron in Escherichia coli carrying blaCTX-M-9. Antimicrob. Agents Chemother. 46:2656-2661.[Abstract/Free Full Text]
    17. 17
  17. Tran, J. H., and G. A. Jacoby. 2002. Mechanism of plasmid-mediated quinolone resistance. Proc. Natl. Acad. Sci. USA 99:5638-5642.[Abstract/Free Full Text]
    18. 18
  18. Tran, J. H., G. A. Jacoby, and D. C. Hooper. 2005. Interaction of the plasmid-encoded quinolone resistance protein Qnr with Escherichia coli DNA gyrase. Antimicrob. Agents Chemother. 49:118-125.[Abstract/Free Full Text]
    19. 19
  19. Tran, J. H., G. A. Jacoby, and D. C. Hooper. 2005. Interaction of the plasmid-encoded quinolone resistance protein QnrA with Escherichia coli topoisomerase IV. Antimicrob. Agents Chemother. 49:3050-3052.[Abstract/Free Full Text]
    20. 20
  20. Yagi, T., H. Kurokawa, N. Shibata, K. Shibayama, and Y. Arakawa. 2000. A preliminary survey of extended-spectrum ß-lactamases (ESBLs) in clinical isolates of Klebsiella pneumoniae and Escherichia coli in Japan. FEMS Microbiol. Lett. 184:53-56.[Medline]

Antimicrobial Agents and Chemotherapy, April 2006, p. 1178-1182, Vol. 50, No. 4
0066-4804/06/$08.00+0     doi:10.1128/AAC.50.4.1178-1182.2006
Copyright © 2006, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Hammerl, J. A., Beutlich, J., Hertwig, S., Mevius, D., Threlfall, E. J., Helmuth, R., Guerra, B. (2009). pSGI15, a small ColE-like qnrB19 plasmid of a Salmonella enterica serovar Typhimurium strain carrying Salmonella genomic island 1 (SGI1). J Antimicrob Chemother 0: dkp383v1-dkp383 [Full Text]  
  • Strahilevitz, J., Jacoby, G. A., Hooper, D. C., Robicsek, A. (2009). Plasmid-Mediated Quinolone Resistance: a Multifaceted Threat. Clin. Microbiol. Rev. 22: 664-689 [Abstract] [Full Text]  
  • Chmelnitsky, I., Hermesh, O., Navon-Venezia, S., Strahilevitz, J., Carmeli, Y. (2009). Detection of aac(6')-Ib-cr in KPC-producing Klebsiella pneumoniae isolates from Tel Aviv, Israel. J Antimicrob Chemother 64: 718-722 [Abstract] [Full Text]  
  • Govender, N., Smith, A. M., Karstaedt, A. S., Keddy, K. H., for the Group for Enteric, Respiratory and Meninge, (2009). Plasmid-mediated quinolone resistance in Salmonella from South Africa. J Med Microbiol 58: 1393-1394 [Full Text]  
  • Gutierrez, B., Herrera-Leon, S., Escudero, J. A., Hidalgo, L., Gonzalez-Sanz, R., Arroyo, M., San Millan, A., Echeita, M. A., Gonzalez-Zorn, B. (2009). Novel genetic environment of qnrB2 associated with TEM-1 and SHV-12 on pB1004, an IncHI2 plasmid, in Salmonella Bredeney BB1047 from Spain. J Antimicrob Chemother 0: dkp340v1-dkp340 [Full Text]  
  • Dionisi, A. M., Lucarelli, C., Owczarek, S., Luzzi, I., Villa, L. (2009). Characterization of the Plasmid-Borne Quinolone Resistance Gene qnrB19 in Salmonella enterica Serovar Typhimurium. Antimicrob. Agents Chemother. 53: 4019-4021 [Abstract] [Full Text]  
  • Cavaco, L. M., Aarestrup, F. M. (2009). Evaluation of Quinolones for Use in Detection of Determinants of Acquired Quinolone Resistance, Including the New Transmissible Resistance Mechanisms qnrA, qnrB, qnrS, and aac(6')Ib-cr, in Escherichia coli and Salmonella enterica and Determinations of Wild-Type Distributions. J. Clin. Microbiol. 47: 2751-2758 [Abstract] [Full Text]  
  • Rodriguez, I., Barownick, W., Helmuth, R., Mendoza, M. C., Rodicio, M. R., Schroeter, A., Guerra, B. (2009). Extended-spectrum {beta}-lactamases and AmpC {beta}-lactamases in ceftiofur-resistant Salmonella enterica isolates from food and livestock obtained in Germany during 2003-07. J Antimicrob Chemother 64: 301-309 [Abstract] [Full Text]  
  • Cano, M. E., Rodriguez-Martinez, J. M., Aguero, J., Pascual, A., Calvo, J., Garcia-Lobo, J. M., Velasco, C., Francia, M. V., Martinez-Martinez, L. (2009). Detection of Plasmid-Mediated Quinolone Resistance Genes in Clinical Isolates of Enterobacter spp. in Spain. J. Clin. Microbiol. 47: 2033-2039 [Abstract] [Full Text]  
  • Szczepanowski, R., Linke, B., Krahn, I., Gartemann, K.-H., Gutzkow, T., Eichler, W., Puhler, A., Schluter, A. (2009). Detection of 140 clinically relevant antibiotic-resistance genes in the plasmid metagenome of wastewater treatment plant bacteria showing reduced susceptibility to selected antibiotics. Microbiology 155: 2306-2319 [Abstract] [Full Text]  
  • Rodriguez-Martinez, J. M., Briales, A., Velasco, C., Conejo, M. C., Martinez-Martinez, L., Pascual, A. (2009). Mutational analysis of quinolone resistance in the plasmid-encoded pentapeptide repeat proteins QnrA, QnrB and QnrS. J Antimicrob Chemother 63: 1128-1134 [Abstract] [Full Text]  
  • Wang, M., Guo, Q., Xu, X., Wang, X., Ye, X., Wu, S., Hooper, D. C., Wang, M. (2009). New Plasmid-Mediated Quinolone Resistance Gene, qnrC, Found in a Clinical Isolate of Proteus mirabilis. Antimicrob. Agents Chemother. 53: 1892-1897 [Abstract] [Full Text]  
  • Merens, A., Matrat, S., Aubry, A., Lascols, C., Jarlier, V., Soussy, C.-J., Cavallo, J.-D., Cambau, E. (2009). The Pentapeptide Repeat Proteins MfpAMt and QnrB4 Exhibit Opposite Effects on DNA Gyrase Catalytic Reactions and on the Ternary Gyrase-DNA-Quinolone Complex. J. Bacteriol. 191: 1587-1594 [Abstract] [Full Text]  
  • Warburg, G., Korem, M., Robicsek, A., Engelstein, D., Moses, A. E., Block, C., Strahilevitz, J. (2009). Changes in aac(6')-Ib-cr Prevalence and Fluoroquinolone Resistance in Nosocomial Isolates of Escherichia coli Collected from 1991 through 2005. Antimicrob. Agents Chemother. 53: 1268-1270 [Abstract] [Full Text]  
  • Ma, J., Zeng, Z., Chen, Z., Xu, X., Wang, X., Deng, Y., Lu, D., Huang, L., Zhang, Y., Liu, J., Wang, M. (2009). High Prevalence of Plasmid-Mediated Quinolone Resistance Determinants qnr, aac(6')-Ib-cr, and qepA among Ceftiofur-Resistant Enterobacteriaceae Isolates from Companion and Food-Producing Animals. Antimicrob. Agents Chemother. 53: 519-524 [Abstract] [Full Text]  
  • Cavaco, L. M., Hasman, H., Xia, S., Aarestrup, F. M. (2009). qnrD, a Novel Gene Conferring Transferable Quinolone Resistance in Salmonella enterica Serovar Kentucky and Bovismorbificans Strains of Human Origin. Antimicrob. Agents Chemother. 53: 603-608 [Abstract] [Full Text]  
  • Wang, M., Jacoby, G. A., Mills, D. M., Hooper, D. C. (2009). SOS Regulation of qnrB Expression. Antimicrob. Agents Chemother. 53: 821-823 [Abstract] [Full Text]  
  • Kim, H. B., Park, C. H., Kim, C. J., Kim, E.-C., Jacoby, G. A., Hooper, D. C. (2009). Prevalence of Plasmid-Mediated Quinolone Resistance Determinants over a 9-Year Period. Antimicrob. Agents Chemother. 53: 639-645 [Abstract] [Full Text]  
  • Morgan-Linnell, S. K., Becnel Boyd, L., Steffen, D., Zechiedrich, L. (2009). Mechanisms Accounting for Fluoroquinolone Resistance in Escherichia coli Clinical Isolates. Antimicrob. Agents Chemother. 53: 235-241 [Abstract] [Full Text]  
  • Pomba, C., da Fonseca, J. D., Baptista, B. C., Correia, J. D., Martinez-Martinez, L. (2009). Detection of the Pandemic O25-ST131 Human Virulent Escherichia coli CTX-M-15-Producing Clone Harboring the qnrB2 and aac(6')-Ib-cr Genes in a Dog. Antimicrob. Agents Chemother. 53: 327-328 [Full Text]  
  • Jones, G. Ll., Warren, R. E., Skidmore, S. J., Davies, V. A., Gibreel, T., Upton, M. (2008). Prevalence and distribution of plasmid-mediated quinolone resistance genes in clinical isolates of Escherichia coli lacking extended-spectrum {beta}-lactamases. J Antimicrob Chemother 62: 1245-1251 [Abstract] [Full Text]  
  • Yang, H., Chen, H., Yang, Q., Chen, M., Wang, H. (2008). High Prevalence of Plasmid-Mediated Quinolone Resistance Genes qnr and aac(6')-Ib-cr in Clinical Isolates of Enterobacteriaceae from Nine Teaching Hospitals in China. Antimicrob. Agents Chemother. 52: 4268-4273 [Abstract] [Full Text]  
  • Tamang, M. D., Seol, S. Y., Oh, J.-Y., Kang, H. Y., Lee, J. C., Lee, Y. C., Cho, D. T., Kim, J. (2008). Plasmid-Mediated Quinolone Resistance Determinants qnrA, qnrB, and qnrS among Clinical Isolates of Enterobacteriaceae in a Korean Hospital. Antimicrob. Agents Chemother. 52: 4159-4162 [Abstract] [Full Text]  
  • Cattoir, V., Poirel, L., Nordmann, P. (2008). Plasmid-Mediated Quinolone Resistance Pump QepA2 in an Escherichia coli Isolate from France. Antimicrob. Agents Chemother. 52: 3801-3804 [Abstract] [Full Text]  
  • Cattoir, V., Nordmann, P., Silva-Sanchez, J., Espinal, P., Poirel, L. (2008). ISEcp1-Mediated Transposition of qnrB-Like Gene in Escherichia coli. Antimicrob. Agents Chemother. 52: 2929-2932 [Abstract] [Full Text]  
  • Chmelnitsky, I., Navon-Venezia, S., Strahilevitz, J., Carmeli, Y. (2008). Plasmid-Mediated qnrB2 and Carbapenemase Gene blaKPC-2 Carried on the Same Plasmid in Carbapenem-Resistant Ciprofloxacin-Susceptible Enterobacter cloacae Isolates. Antimicrob. Agents Chemother. 52: 2962-2965 [Abstract] [Full Text]  
  • Lascols, C., Podglajen, I., Verdet, C., Gautier, V., Gutmann, L., Soussy, C.-J., Collatz, E., Cambau, E. (2008). A Plasmid-Borne Shewanella algae Gene, qnrA3, and Its Possible Transfer In Vivo between Kluyvera ascorbata and Klebsiella pneumoniae. J. Bacteriol. 190: 5217-5223 [Abstract] [Full Text]  
  • Iabadene, H., Messai, Y., Ammari, H., Ramdani-Bouguessa, N., Lounes, S., Bakour, R., Arlet, G. (2008). Dissemination of ESBL and Qnr determinants in Enterobacter cloacae in Algeria. J Antimicrob Chemother 62: 133-136 [Abstract] [Full Text]  
  • Jacoby, G., Cattoir, V., Hooper, D., Martinez-Martinez, L., Nordmann, P., Pascual, A., Poirel, L., Wang, M. (2008). qnr Gene Nomenclature. Antimicrob. Agents Chemother. 52: 2297-2299 [Full Text]  
  • Wu, J.-J., Ko, W.-C., Wu, H.-M., Yan, J.-J. (2008). Prevalence of Qnr determinants among bloodstream isolates of Escherichia coli and Klebsiella pneumoniae in a Taiwanese Hospital, 1999-2005. J Antimicrob Chemother 61: 1234-1239 [Abstract] [Full Text]  
  • Jiang, Y., Zhou, Z., Qian, Y., Wei, Z., Yu, Y., Hu, S., Li, L. (2008). Plasmid-mediated quinolone resistance determinants qnr and aac(6')-Ib-cr in extended-spectrum {beta}-lactamase-producing Escherichia coli and Klebsiella pneumoniae in China. J Antimicrob Chemother 61: 1003-1006 [Abstract] [Full Text]  
  • Cesaro, A., Bettoni, R. R. D., Lascols, C., Merens, A., Soussy, C. J., Cambau, E. (2008). Low selection of topoisomerase mutants from strains of Escherichia coli harbouring plasmid-borne qnr genes. J Antimicrob Chemother 61: 1007-1015 [Abstract] [Full Text]  
  • Yamane, K., Wachino, J.-i., Suzuki, S., Arakawa, Y. (2008). Plasmid-Mediated qepA Gene among Escherichia coli Clinical Isolates from Japan. Antimicrob. Agents Chemother. 52: 1564-1566 [Abstract] [Full Text]  
  • Aschbacher, R., Doumith, M., Livermore, D. M., Larcher, C., Woodford, N. (2008). Linkage of acquired quinolone resistance (qnrS1) and metallo-{beta}-lactamase (blaVIM-1) genes in multiple species of Enterobacteriaceae from Bolzano, Italy. J Antimicrob Chemother 61: 515-523 [Abstract] [Full Text]  
  • Kehrenberg, C., Friederichs, S., de Jong, A., Schwarz, S. (2008). Novel Variant of the qnrB Gene, qnrB12, in Citrobacter werkmanii. Antimicrob. Agents Chemother. 52: 1206-1207 [Full Text]  
  • Kang, H. Y., Kim, K. Y., Kim, J., Lee, J. C., Lee, Y. C., Cho, D. T., Seol, S. Y. (2008). Distribution of Conjugative-Plasmid-Mediated 16S rRNA Methylase Genes among Amikacin-Resistant Enterobacteriaceae Isolates Collected in 1995 to 1998 and 2001 to 2006 at a University Hospital in South Korea and Identification of Conjugative Plasmids Mediating Dissemination of 16S rRNA Methylase. J. Clin. Microbiol. 46: 700-706 [Abstract] [Full Text]  
  • Chau, T. T., Campbell, J. I., Galindo, C. M., Van Minh Hoang, N., Diep, T. S., Nga, T. T. T., Van Vinh Chau, N., Tuan, P. Q., Page, A. L., Ochiai, R. L., Schultsz, C., Wain, J., Bhutta, Z. A., Parry, C. M., Bhattacharya, S. K., Dutta, S., Agtini, M., Dong, B., Honghui, Y., Anh, D. D., Canh, D. G., Naheed, A., Albert, M. J., Phetsouvanh, R., Newton, P. N., Basnyat, B., Arjyal, A., La, T. T. P., Rang, N. N., Phuong, L. T., Van Be Bay, P., von Seidlein, L., Dougan, G., Clemens, J. D., Vinh, H., Hien, T. T., Chinh, N. T., Acosta, C. J., Farrar, J., Dolecek, C. (2007). Antimicrobial Drug Resistance of Salmonella enterica Serovar Typhi in Asia and Molecular Mechanism of Reduced Susceptibility to the Fluoroquinolones. Antimicrob. Agents Chemother. 51: 4315-4323 [Abstract] [Full Text]  
  • Quiroga, M. P., Andres, P., Petroni, A., Soler Bistue, A. J. C., Guerriero, L., Vargas, L. J., Zorreguieta, A., Tokumoto, M., Quiroga, C., Tolmasky, M. E., Galas, M., Centron, D. (2007). Complex Class 1 Integrons with Diverse Variable Regions, Including aac(6')-Ib-cr, and a Novel Allele, qnrB10, Associated with ISCR1 in Clinical Enterobacterial Isolates from Argentina. Antimicrob. Agents Chemother. 51: 4466-4470 [Abstract] [Full Text]  
  • Xu, X., Wu, S., Ye, X., Liu, Y., Shi, W., Zhang, Y., Wang, M. (2007). Prevalence and Expression of the Plasmid-Mediated Quinolone Resistance Determinant qnrA1. Antimicrob. Agents Chemother. 51: 4105-4110 [Abstract] [Full Text]  
  • Ambrozic Avgustin, J., Keber, R., Zerjavic, K., Orazem, T., Grabnar, M. (2007). Emergence of the Quinolone Resistance-Mediating Gene aac(6')-Ib-cr in Extended-Spectrum-{beta}-Lactamase-Producing Klebsiella Isolates Collected in Slovenia between 2000 and 2005. Antimicrob. Agents Chemother. 51: 4171-4173 [Abstract] [Full Text]  
  • Park, Y.-J., Yu, J. K., Lee, S., Oh, E.-J., Woo, G.-J. (2007). Prevalence and diversity of qnr alleles in AmpC-producing Enterobacter cloacae, Enterobacter aerogenes, Citrobacter freundii and Serratia marcescens: a multicentre study from Korea. J Antimicrob Chemother 60: 868-871 [Abstract] [Full Text]  
  • Cavaco, L. M., Hendriksen, R. S., Aarestrup, F. M. (2007). Plasmid-mediated quinolone resistance determinant qnrS1 detected in Salmonella enterica serovar Corvallis strains isolated in Denmark and Thailand. J Antimicrob Chemother 60: 704-706 [Full Text]  
  • Yamane, K., Wachino, J.-i., Suzuki, S., Kimura, K., Shibata, N., Kato, H., Shibayama, K., Konda, T., Arakawa, Y. (2007). New Plasmid-Mediated Fluoroquinolone Efflux Pump, QepA, Found in an Escherichia coli Clinical Isolate. Antimicrob. Agents Chemother. 51: 3354-3360 [Abstract] [Full Text]  
  • Arpin, C., Coulange, L., Dubois, V., Andre, C., Fischer, I., Fourmaux, S., Grobost, F., Jullin, J., Dutilh, B., Couture, J.-F., Noury, P., Lagrange, I., Ducastaing, A., Doermann, H.-P., Quentin, C. (2007). Extended-Spectrum-{beta}-Lactamase-Producing Enterobacteriaceae Strains in Various Types of Private Health Care Centers. Antimicrob. Agents Chemother. 51: 3440-3444 [Abstract] [Full Text]  
  • Arsene, S., Leclercq, R. (2007). Role of a qnr-Like Gene in the Intrinsic Resistance of Enterococcus faecalis to Fluoroquinolones. Antimicrob. Agents Chemother. 51: 3254-3258 [Abstract] [Full Text]  
  • Cattoir, V., Poirel, L., Rotimi, V., Soussy, C.-J., Nordmann, P. (2007). Multiplex PCR for detection of plasmid-mediated quinolone resistance qnr genes in ESBL-producing enterobacterial isolates. J Antimicrob Chemother 60: 394-397 [Abstract] [Full Text]  
  • Strahilevitz, J., Engelstein, D., Adler, A., Temper, V., Moses, A. E., Block, C., Robicsek, A. (2007). Changes in qnr Prevalence and Fluoroquinolone Resistance in Clinical Isolates of Klebsiella pneumoniae and Enterobacter spp. Collected from 1990 to 2005. Antimicrob. Agents Chemother. 51: 3001-3003 [Abstract] [Full Text]  
  • Cattoir, V., Poirel, L., Nordmann, P. (2007). Plasmid-Mediated Quinolone Resistance Determinant QnrB4 Identified in France in an Enterobacter cloacae Clinical Isolate Coexpressing a QnrS1 Determinant. Antimicrob. Agents Chemother. 51: 2652-2653 [Full Text]  
  • Mendonca, N., Leitao, J., Manageiro, V., Ferreira, E., the Antimicrobial Resistance Surveillance Program, , Canica, M. (2007). Spread of Extended-Spectrum {beta}-Lactamase CTX-M-Producing Escherichia coli Clinical Isolates in Community and Nosocomial Environments in Portugal. Antimicrob. Agents Chemother. 51: 1946-1955 [Abstract] [Full Text]  
  • Tumbarello, M., Sanguinetti, M., Montuori, E., Trecarichi, E. M., Posteraro, B., Fiori, B., Citton, R., D'Inzeo, T., Fadda, G., Cauda, R., Spanu, T. (2007). Predictors of Mortality in Patients with Bloodstream Infections Caused by Extended-Spectrum-{beta}-Lactamase-Producing Enterobacteriaceae: Importance of Inadequate Initial Antimicrobial Treatment. Antimicrob. Agents Chemother. 51: 1987-1994 [Abstract] [Full Text]  
  • Hopkins, K. L., Wootton, L., Day, M. R., Threlfall, E. J. (2007). Plasmid-mediated quinolone resistance determinant qnrS1 found in Salmonella enterica strains isolated in the UK. J Antimicrob Chemother 59: 1071-1075 [Abstract] [Full Text]  
  • Cavaco, L. M., Hansen, D. S., Friis-Moller, A., Aarestrup, F. M., Hasman, H., Frimodt-Moller, N. (2007). First detection of plasmid-mediated quinolone resistance (qnrA and qnrS) in Escherichia coli strains isolated from humans in Scandinavia. J Antimicrob Chemother 59: 804-805 [Full Text]  
  • Wu, J.-J., Ko, W.-C., Tsai, S.-H., Yan, J.-J. (2007). Prevalence of Plasmid-Mediated Quinolone Resistance Determinants QnrA, QnrB, and QnrS among Clinical Isolates of Enterobacter cloacae in a Taiwanese Hospital. Antimicrob. Agents Chemother. 51: 1223-1227 [Abstract] [Full Text]  
  • Poirel, L., Cattoir, V., Soares, A., Soussy, C.-J., Nordmann, P. (2007). Novel Ambler Class A {beta}-Lactamase LAP-1 and Its Association with the Plasmid-Mediated Quinolone Resistance Determinant QnrS1. Antimicrob. Agents Chemother. 51: 631-637 [Abstract] [Full Text]  
  • Pai, H., Seo, M.-R., Choi, T. Y. (2007). Association of QnrB Determinants and Production of Extended-Spectrum {beta}-Lactamases or Plasmid-Mediated AmpC {beta}-Lactamases in Clinical Isolates of Klebsiella pneumoniae. Antimicrob. Agents Chemother. 51: 366-368 [Abstract] [Full Text]  
  • Poirel, L., Leviandier, C., Nordmann, P. (2006). Prevalence and Genetic Analysis of Plasmid-Mediated Quinolone Resistance Determinants QnrA and QnrS in Enterobacteriaceae Isolates from a French University Hospital. Antimicrob. Agents Chemother. 50: 3992-3997 [Abstract] [Full Text]  
  • Lavigne, J.-P., Marchandin, H., Delmas, J., Bouziges, N., Lecaillon, E., Cavalie, L., Jean-Pierre, H., Bonnet, R., Sotto, A. (2006). qnrA in CTX-M-Producing Escherichia coli Isolates from France. Antimicrob. Agents Chemother. 50: 4224-4228 [Abstract] [Full Text]  
  • Soge, O. O., Adeniyi, B. A., Roberts, M. C. (2006). New antibiotic resistance genes associated with CTX-M plasmids from uropathogenic Nigerian Klebsiella pneumoniae. J Antimicrob Chemother 58: 1048-1053 [Abstract] [Full Text]  
  • Chen, Y.-T., Shu, H.-Y., Li, L.-H., Liao, T.-L., Wu, K.-M., Shiau, Y.-R., Yan, J.-J., Su, I.-J., Tsai, S.-F., Lauderdale, T.-L. (2006). Complete Nucleotide Sequence of pK245, a 98-Kilobase Plasmid Conferring Quinolone Resistance and Extended-Spectrum-{beta}-Lactamase Activity in a Clinical Klebsiella pneumoniae Isolate. Antimicrob. Agents Chemother. 50: 3861-3866 [Abstract] [Full Text]  
  • Park, C. H., Robicsek, A., Jacoby, G. A., Sahm, D., Hooper, D. C. (2006). Prevalence in the United States of aac(6')-Ib-cr Encoding a Ciprofloxacin-Modifying Enzyme. Antimicrob. Agents Chemother. 50: 3953-3955 [Abstract] [Full Text]  
  • Orlen, H., Hughes, D. (2006). Weak Mutators Can Drive the Evolution of Fluoroquinolone Resistance in Escherichia coli.. Antimicrob. Agents Chemother. 50: 3454-3456 [Abstract] [Full Text]  
  • Turner, A. K., Nair, S., Wain, J. (2006). The acquisition of full fluoroquinolone resistance in Salmonella Typhi by accumulation of point mutations in the topoisomerase targets. J Antimicrob Chemother 58: 733-740 [Abstract] [Full Text]  
  • Bonemann, G., Stiens, M., Puhler, A., Schluter, A. (2006). Mobilizable IncQ-Related Plasmid Carrying a New Quinolone Resistance Gene, qnrS2, Isolated from the Bacterial Community of a Wastewater Treatment Plant.. Antimicrob. Agents Chemother. 50: 3075-3080 [Abstract] [Full Text]  
  • Zimhony, O., Chmelnitsky, I., Bardenstein, R., Goland, S., Hammer Muntz, O., Navon Venezia, S., Carmeli, Y. (2006). Endocarditis Caused by Extended-Spectrum-{beta}-Lactamase-Producing Klebsiella pneumoniae: Emergence of Resistance to Ciprofloxacin and Piperacillin-Tazobactam during Treatment despite Initial Susceptibility.. Antimicrob. Agents Chemother. 50: 3179-3182 [Abstract] [Full Text]  
  • Machado, E., Coque, T. M., Canton, R., Baquero, F., Sousa, J. C., Peixe, L., The Portuguese Resistance Study Group, (2006). Dissemination in Portugal of CTX-M-15-, OXA-1-, and TEM-1-Producing Enterobacteriaceae Strains Containing the aac(6')-Ib-cr Gene, Which Encodes an Aminoglycoside- and Fluoroquinolone-Modifying Enzyme.. Antimicrob. Agents Chemother. 50: 3220-3221 [Full Text]  
  • Robicsek, A., Strahilevitz, J., Sahm, D. F., Jacoby, G. A., Hooper, D. C. (2006). qnr Prevalence in Ceftazidime-Resistant Enterobacteriaceae Isolates from the United States.. Antimicrob. Agents Chemother. 50: 2872-2874 [Abstract] [Full Text]  
  • Guerrant, R. L. (2006). Cholera--still teaching hard lessons.. NEJM 354: 2500-2502 [Full Text]  
  • Jacoby, G. A., Walsh, K. E., Walker, V. J. (2006). Identification of Extended-Spectrum, AmpC, and Carbapenem- Hydrolyzing {beta}-Lactamases in Escherichia coli and Klebsiella pneumoniae by Disk Tests.. J. Clin. Microbiol. 44: 1971-1976 [Abstract] [Full Text]  

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Jacoby, G. A.
Right arrow Articles by Hooper, D. C.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Jacoby, G. A.
Right arrow Articles by Hooper, D. C.

Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»