Journal List > Korean J Lab Med > v.29(6) > 1011596

Shin, Kwon, Park, Song, Ko, Sung, Shin, and Koo: Characteristics of aac(6′)-Ib-cr Gene in Extended-Spectrum β-Lactamase-Producing Escherichia coli and Klebsiella pneumoniae Isolated from Chungnam Area

Abstract

Background:

Concomitant quinolone resistance in extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae is a crucial problem in the clinical management of infections. In foreign countries, the fluoroquinolone acetylating aminoglycoside-(6)-N-acetyltransferase (aac[6′]-Ib-cr) gene, a novel plasmid-mediated quinolone resistance determinant has been reported to occur in conjunction with qnr. We aim to investigate the prevalence and characteristics of concomitant aac(6′)-Ib-cr and qnr expression in ESBL-producing Escherichia coli and Klebsiella pneumoniae in Korea.

Methods:

Between December 2007 and April 2008, we collected 60 and 69 clonally unrelated non-repetitive clinical isolates of ESBL-producing E. coli and K. pneumoniae, respectively. We studied the expressions of 11 types of ESBL-encoding genes, 4 types of 16s rRNA methylase genes; rmtA, rmtB, rmtC and armA, 3 types of qnr genes; qnrA, qnrB, qnrS and aac(6′)-Ib. The presence of aac(6′)-Ib-cr variants was detected by sequencing. The involvement of integrons was studied using multiplex PCR and sequencing of gene-cassette arrays. Conjugation experiments were performed to confirm plasmid-mediated resistance and the relationships among coharbored genes.

Results:

We observed a high prevalence of the cr variant (61.1%) of aac(6′)-Ib, and the prevalence of this variant in qnr and aac(6′)-Ib-coharboring isolates (67.4%) was higher than in qnr-negative isolates (51.7%). The high prevalence of the cr variant was significantly related to the high minimum inhibitory concentrations (MICs) of ciprofloxacin, tobramycin, and amikacin and indicated the statistically significant roles of qnrB, qnrS, rmtA, and rmtB in quinolone and aminoglycoside resistance.

Conclusions:

The aac(6′)-Ib-cr variants were widespread and showed significant relation to the high-level quinolone and aminoglycoside resistance in ESBL-producing E. coli and K. pneumoniae. (Korean J Lab Med 2009;29:541-50)

REFERENCES

1.Podschun R., Ullmann U. Klebsiella spp. as nosocomial pathogens: epidemiology, taxonomy, typing methods and pathogenicity factors. Clin Microbiol Rev. 1998. 11:589–603.
2.Garau J., Xercavins M., Rodríguez-Carballeira M., Gómez-Vera JR., Coll I., Vidal D, et al. Emergence and dissemination of quinolone-resistant Escherichia coli in the community. Antimicrob Agents Chemother. 1999. 43:2736–41.
3.Lautenbach E., Strom BL., Bilker WB., Patel JB., Edelstein PH., Fishman NO. Epidemiological investigation of fluoroquinolone resistance in infections due to extended-spectrum β-lactamase-producing Escherichia Coli and Klebsiella pneumoniae. Clin Infect Dis. 2001. 33:1288–94.
4.Ling TK., Xiong J., Yu Y., Lee CC., Ye H., Hawkey PM. Multicenter antimicrobial susceptibility survey of gram-negative bacteria isolated from patients with community-acquired infections in the People's Republic of China. Antimicrob Agents Chemother. 2006. 50:374–8.
crossref
5.Jacoby GA., Chow N., Waites KB. Prevalence of plasmid-mediated quinolone resistance. Antimicrob Agents Chemother. 2003. 47:559–62.
crossref
6.Martínez-Martínez L., Pascual A., Jacoby GA. Quinolone resistance from a transferable plasmid. Lancet. 1998. 351:797–9.
crossref
7.Klugman KP., Levin BR. One enzyme inactivates two antibiotics. Nat Med. 2006. 12:19–20.
crossref
8.Clinical and Laboratory Standards Institute. Performance standards for antimicrobial susceptibility testing: seventeenth informational supplement M100-S17. Wayne, PA: CLSI. 2007.
9.Kang JH., Bae IK., Kwon SB., Jeong SH., Lee JW., Lee WG. Prevalence of Ambler Class A extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae isolates in Korea. Korean J Clin Microbiol. 2005. 8:17–25. (강지혜, 배일권, 권수봉, 정석훈, 이종욱, 이위교등. Ambler Class A extended-spectrum β-lactamase 생성 Escherichia coliKlebsiella pneumoniae 의 국내 분리 현황. 대한임상미생물학회지 2005;8:17-25.).
10.Cattoir V., Weill FX., Poirel L., Fabre L., Soussy CJ., Nordmann P. Prevalence of qnr genes in Salmonella in France. J Antimicrob Chemother. 2007. 59:751–4.
11.Bogaerts P., Galimand M., Bauraing C., Deplano A., Vanhoof R., De Mendonca R, et al. Emergence of ArmA and RmtB aminoglycoside resistance 16S rRNA methylases in Belgium. J Antimicrob Chemother. 2007. 59:459–64.
12.Park YJ., Lee S., Yu JK., Woo GJ., Lee K., Arakawa Y. Co-production of 16S rRNA methylases and extended-spectrum β-lactamases in AmpC-producing Enterobacter cloacae, Citrobacter freundii and Serratia marcescens in Korea. J Antimicrob Chemother. 2006. 58:907–8.
13.Fihman V., Lartigue MF., Jacquier H., Meunier F., Schnepf N., Raskine L, et al. Appearance of aac(6′)-Ib-cr gene among extended-spectrum β-lactamase-producing Enterobacteriaceae in a French hospital. J Infect. 2008. 56:454–9.
14.Dillon B., Thomas L., Mohmand G., Zelynski A., Iredell J. Multiplex PCR for screening of integrons in bacterial lysates. J Microbiol Methods. 2005. 62:221–32.
crossref
15.White PA., McIver CJ., Rawlinson WD. Integrons and gene cassettes in the enterobacteriaceae. Antimicrob Agents Chemother. 2001. 45:2658–61.
16.Jeong JY., Yoon HJ., Kim ES., Lee Y., Choi SH., Kim NJ, et al. Detection of qnr in clinical isolates of Escherichia coli from Korea. Antimicrob Agents Chemother. 2005. 49:2522–4.
17.Kim MH., Sung JY., Park JW., Kwon GC., Koo SH. Coproduction of qnrB and armA from extended-spectrum β-lactamase-producing Klebsiella pneumoniae. Korean J Lab Med. 2007. 27:428–36. (김문희, 성지연, 박종우, 권계철, 구선회. Extended-spectrum β-lactamase 를생성하는 Klebsiella pneumoniae 에서의 qnrBarmA 유전자의동시생성.대한진단검사의학회지 2007;27:428-36.).
18.Versalovic J., Koeuth T., Lupski JR. Distribution of repetitive DNA sequences in eubacteria and application to fingerprinting of bacterial genomes. Nucleic Acids Res. 1991. 19:6823–31.
19.Poirel L., Pitout JD., Calvo L., Rodriguez-Martinez JM., Church D., Nordmann P. In vivo selection of fluoroquinolone-resistant Escherichia coli isolates expressing plasmid-mediated quinolone resistance and expanded-spectrum β-lactamase. Antimicrob Agents Chemother. 2006. 50:1525–7.
20.Robicsek A., Jacoby GA., Hooper DC. The worldwide emergence of plasmid-mediated quinolone resistance. Lancet Infect Dis. 2006. 6:629–40.
crossref
21.Jiang Y., Zhou Z., Qian Y., Wei Z., Yu Y., Hu S, et al. Plasmid-mediated quinolone resistance determinants qnr and aac(6′)-Ib-cr in extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae in China. J Antimicrob Chemother. 2008. 61:1003–6.
22.Park CH., Robicsek A., Jacoby GA., Sahm D., Hooper DC. Prevalence in the United States of aac(6′)-Ib-cr encoding a ciprofloxacin-modifying enzyme. Antimicrob Agents Chemother. 2006. 50:3953–5.
23.Szabó D., Kocsis B., Rókusz L., Szentandrássy J., Katona K., Kristóf K, et al. First detection of plasmid-mediated, quinolone resistance determinants qnrA, qnrB, qnrS and aac(6′)-Ib-cr in extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae in Budapest, Hungary. J Antimicrob Chemother. 2008. 62:630–2.
24.Robicsek A., Strahilevitz J., Jacoby GA., Macielag M., Abbanat D., Park CH, et al. Fluoroquinolone-modifying enzyme: a n adaptation of a common aminoglycoside acetyltransferase. Nat Med. 2006. 12:83–8.
25.Robicsek A., Strahilevitz J., Sahm DF., Jacoby GA., Hooper DC. qnr prevalence in ceftazidime-resistant Enterobacteriaceae isolates from the United States. Antimicrob Agents Chemother. 2006. 50:2872–4.
26.Fluit AC., Schmitz FJ. Class 1 integrons, gene cassettes, mobility, and epidemiology. Eur J Clin Microbiol Infect Dis. 1999. 18:761–70.
crossref
27.Collis CM., Hall RM. Expression of antibiotic resistance genes in the integrated cassettes of integrons. Antimicrob Agents Chemother. 1995. 39:155–62.
crossref
28.Park YJ., Yu JK., Lee S., Oh EJ., Woo GJ. 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. 2007. 60:868–71.

Table 1.
Oligonucleotides of the primers used for amplification
Enzymes Primer pairs Target Sequence (5′-3′) Amplicon size (bp) Reference
b-lactamase TEM F blaTEM & variants ATG AGT ATT CAA CAT TTC CGT 861 [9], In this study
  TEM R   TTA CCA ATG CTT AAT CAG TGA    
  SHV F blaSHV & variants CCG GGT TAT TCT TAT TTG TCG CT 831  
  SHV R   TAG CGT TGC CAG TGC TCG    
  PER-F blaPER GTT AAT TTG GGC TTA GGG CAG 855  
  PER-R   CAG CGC AAT CCC CAC TGT    
  GES/IBC F blaGES-1, blaGES-2, IBC-1 GTT AGA CGG GCG TAC AAA GAT AAT 903  
  GES/IBC R   TGT CCG TGC TCA GGA TGA GT    
  CTX-MF blaCTX-M-1,2,9 cluster GAT TGA CCG TAT TGG GAG TTT 947  
  CTX-MR   CGG CTG GGT AAA ATA GGT CA    
  CTX-M3F blaCTX-M-3 AGT TCA CGC TGA TGG CGA CG 602  
  CTX-M3R   AAC CCA GGA AGC AGG CAG CG    
  CTX-M8F blaCTX-M-8 ACG CTC AAC ACC GCG ATC 954  
  CTX-M8R   CGT GGG TTC TCG GGG ATA A    
  VEB F blaVEB CGA CTT CCA TTT CCC GAT GC 650  
  VEB R   GGA CTC TGC AAC AAA TAC GC    
Qnr qnrA F qnrA GGG TAT GGA TAT TAT TGA TAA AG 660 [10]
  qnrA R   CTA ATC CGG CAG CAC TAT TA    
  qnrB F qnrB1-6 variants GGM ATH GAA ATT CGC CAC TG 264  
  qnrB R   TTT GCY GYY CGC CAG TCG AA    
  qnrS F qnrS AGT GAT CTC ACC TTC ACC GC 550  
  qnrS R   CAG GCT GCA ATT TTG ATA CC    
16S rRNA methylase armA F armA AGG TTG TTT CCA TTT CTG AG 776 [11,12]
  armA R   TCT CTT CCA TTC CCT TCT CC    
  rmtA F rmtA CTAGCGTCCATCCTTTCCTC 635  
  rmtA R   TTT GCT TCC ATG CCC TTG CC    
  rmtB F rmtB CCC AAA CAG ACC GTA GAG GC 769  
  rmtB R   CTC AAA CTC GGC GGG CAA GC    
  rmtC F rmtC CGA AGA AGT AAC AGC CAA AG 700  
  rmtC R   ATC CCA ACA TCT CTC CCA CT    
aac(6′)-Ib aac(6′)F aac(6′)-Ib TGA CCA ACA GCA ACG ATT CC 500 [13]
  aac(6′)R   TTA GGC ATC ACT GCG TGT TC    

Abbreviations: F, forward; R, reverse.

Table 2.
Species-specific distributions of antibiotic resistance genes
Genes Escherichia coli N=60 (%) Klebsiella pneumoniae N=69 (%) Total N=129 P value
blaTEM 41 (68.3) 33 (47.8) 74 (57.0) 0.03
blaSHV 5 (8.3) 65 (94.2) 70 (54.0) ≤0.0001
blaCTX-M-1 34 (56.7) 11 (15.9) 45 (35.0) ≤0.0001
blaCTX-M-2 2 (3.3) 11 (15.9) 13 (10.0) 0.02
blaCTX-M-3 18 (30.0) 12 (17.4) 30 (23.0) 0.1384
blaCTX-M-8 6 (10.0) 4 (5.8) 10 (8.0) 0.5127
blaCTX-M-9 34 (56.7) 8 (11.6) 42 (33.0) ≤0.0001
blaGES 0 (0) 5 (7.2) 5 (4.0) 0.0607
blaVEB 0 (0) 1 (1.4) 1 (1.0) 1
rmtA 4 (6.7) 7 (10.1) 11 (9.0) 0.5424
rmtB 37 (61.7) 7 (10.1) 44 (34.0) ≤0.0001
armA 14 (23.3) 46 (66.7) 60 (47.0) ≤0.0001
aac(6′)-Ib 39 (65.0) 33 (47.8) 72 (55.8) 0.0748
aac(6′)-Ib-cr 25/39 (64.1) 19/33 (57.6) 44 (61.1)  
wild-type 14/39 (35.9) 14/33 (42.4) 28 (38.9)  
qnrA 0 (0) 1 (1.4) 1 (1.0) 1
qnrB 1 (1.7) 49 (71.0) 50 (39.0) ≤0.0001
qnrS 24 (40.0) 5 (7.2) 29 (22.0) ≤0.0001

Statistical analysis for categorical variables and incidence across series were performed using Pearson's chi test and Fisher's exact tests;

The ratio of cr-variants to the isolates carrying aac(6′)-Ib.

Table 3.
Prevalence of the qnr subtypes and the cr-variant in the 43 strains coharboring qnr and aac(6′)-Ib
Strain (N [%]) qnrA positive qnrB positive qnrS positive aac(6′)-Ib-cr
Escherichia coli 19 0 (0) 0 (0) 19 (100) 12 (63.2)
Klebsiella pneumoniae 24 1 (0.04) 21 (87.5) 3 (12.5) 17 (70.8)
Total 43 1 (0.02) 21 (48.8) 22 (51.2) 29 (67.4)
Table 4.
Cassette arrays of the type-1 integrons detected in the 43 strains coharboring qnr and aac(6′)-Ib
Type of cassette array Sequence of cassette Size (kb) Isolates
Escherichia coli Klebsiella pneumoniae
1 dfr17-aadA5 1.8 5 0
2 aadA2 1.1 0 12
3 aadB-aadA2 1.6 0 1
4 aac(6′)-Ib-cm1a1 2.5 1 0
5 aac(6′)-Ib-blaOXA4-aadA2 3.0 0 1
6 aadA6-OfrD 1.2 0 1
Total     5 15

Simultaneously harbored type 1 cassette array in the isolate.

Table 5.
Minimum inhibitory concentration values and resistance gene profiles of the 11 strains showing high-level resistances to quinolone or aminoglycoside
Species No. strain Array type aac(6′) qnrA qnrB qnrS armA rmtA rmtB NOR CIP TOB GEN AMK
Escherichia coli 100 . Ib N N P P N P >128 >32 16 >128 64
  23 1,4 Ib N N P N N N >128 >32 16 16 8
  21 1 Ib N N P P N P >128 >32 4 16 ≤2
Klebsiella pneumoniae 126 . cr N P N N N N >128 >32 >128 >128 >512
  37 . cr N P N P N N >128 >32 >128 32 >512
  42 . cr N P N N N N >128 8 >128 >128 128
  28 2 cr N P N P N N >128 2 >128 >128 >512
  31 . cr N P N P N N >128 4 64 >128 >512
  33 6 cr N P N P N N >128 4 >128 >128 64
  45 2 cr N P N P N N >128 2 >128 64 64
  44 2 cr N P N P N N >128 2 >128 16 64

Abbreviations: CIP, ciprofloxacin; TOB, tobramycin; GEN, gentamicin; AMK, amikacin; NOR, norfloxacin; N, negative; P, positive.

Table 6.
Candidate resistance genes showing statistical association with the minimum inhibitory concentration values of quinolones and aminoglycosides in the 43 strains cohaboring qnr and wild-type aac(6′)-Ib
    N NOR CIP TOB GEN AMK
qnrB Positive 21     53.4±55.3 40.5±51.9 136±190
  Negative 22     11.5±5.6 15.5±26.6 14.2±21.3
  P value       ≤0.001 0.0044 ≤0.001
qnrS Positive 22       14.8±26.8 11.6±18
  Negative 21       41.2±51.4 138.6±188.5
  P value         0.0054 ≤0.001
rmtA Positive 4 6±2.3 2.1±2.0 9.2±7.8 9.2±7.8 19.5±29.7
  Negative 39 41.8±55.7 7±9.7 34.9±45.8 30±44.4 81.0±153.3
  P value   0.0002 0.025 0.0139 0.0153 0.0199
rmtB Positive 14     10±6.2   14.7±22.4
  Negative 29     42.5±50.2   102.2±170.2
  P value       ≤0.001   ≤0.001
cr-variant Positive 29   5.2±7.7 42.2±51.6   97.4±175.6
  Negative 14   9±12.5 12.9±5.2   30.5±30.2
  P value     0.0324 ≤0.001   ≤0.001

The Wilcoxon rank-sum test was used to compare the group mean (negative vs positive) values; P≤0.05 was considered to indicate statistical significance.

Abbreviations: CIP, ciprofloxacin; TOB, tobramycin; GEN, gentamicin; AMK, amikacin; NOR, norfloxacin.

Table 7.
Amplified association between the candidate genes and the minimum inhibitory concentration values of quinolones and amino-glycosides in the 29 strains co-harboring qnr and the cr-variant
    N NOR CIP TOB GEN AMK
qnrB Positive 16 67±63.0 6.0±10.0 65.1±58.9 50.1±56.3 161.5±212.3
  Negative 13 7±1.8 3.5±1.7 11.7±5.5 10.2±7.1 12.0±17.3
  P value   ≤0.001 ≤0.001 ≤0.001 ≤0.001 ≤0.001
qnrS Positive 13 6.6±1.9 6.6±10.0 65.1±58.9   161.5±212.2
  Negative 16 67.2±62.5 3.5±1.1 11.7±5.5   12±17.3
  P value   ≤0.001 ≤0.001 ≤0.001   ≤0.001
rmtA Positive 3       7±7.9  
  Negative 26       36.2±48.6  
  P value         0.0526  
rmtB Positive 8     9.8±6.2   7.1±6.4
  Negative 21     53.0±55.6   127.5±194.5
  P value       ≤0.001   ≤0.001

The Wilcoxon rank-sum test was used to compare the group mean (negative vs positive) values; P≤0.05 was considered to indicate statistical significance.

Abbreviations: See Table 6.

TOOLS
Similar articles