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Antimicrobial Agents and Chemotherapy, February 2008, p. 798-799, Vol. 52, No. 2
0066-4804/08/$08.00+0     doi:10.1128/AAC.01185-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

LETTER TO THE EDITOR

Carbapenem-Resistant Isolates of Klebsiella pneumoniae in China and Detection of a Conjugative Plasmid (blaKPC-2 plus qnrB4) and a blaIMP-4 Gene{triangledown}


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Wei et al. (13) recently described the emergence of plasmid-mediated KPC-2 carbapenemase in a Klebsiella pneumoniae isolate from China. Interestingly, KPC-producing isolates, which were initially restricted to hospitals located in the New York City area (2), have recently been detected in other areas of the United States (5) and in several nations, including China (13), Colombia (11), and Israel (8). This enzyme, considered a problem for clonal spread, has also been detected among other organisms, such as Pseudomonas aeruginosa (10), Escherichia coli (8), and Serratia marcescens (15), emphasizing the global risk of interspecies dissemination of resistance genes. Furthermore, several IMP-type metallo-β-lactamase (MβL) enzymes have been detected in China but most often among nonfermentative gram-negative bacilli (12).

This study selected Enterobacteriaceae isolated during the 2006 SENTRY Antimicrobial Surveillance Program (Asia-Pacific region) with decreased susceptibility (MIC of ≥2 µg/ml) for imipenem or meropenem. The isolates were tested by reference broth microdilution methods (3, 4), and MIC results were interpreted as specified by the M100-S17 CLSI document (4), apart from tigecycline results, which were interpreted according to the breakpoints approved by the U.S. Federal Drug Administration (≤2 or ≥8 µg/ml for susceptible or resistant, respectively). The isolates were screened for KPC and MβL, as recently described (5, 6), followed by gene sequencing. K. pneumoniae clinical isolate 231-21D was recovered from a 42-year-old male trauma victim with a venous catheter infection on the 77th hospital day in Zhejiang, China. The patient had received multiple antimicrobial treatments, including piperacillin-tazobactam for 9 days, metronidazole for 3 days, vancomycin for 10 days, cefoperazone-sulbactam for 19 days, teicoplanin for 15 days, imipenem for 11 days, and levofloxacin for 6 days, when the isolate 231-21D was recovered. Negative blood cultures were obtained after removing the catheter. K. pneumoniae clinical isolate 234-49C was isolated from the sputum of a 50-day-old female infant with acute bronchopneumonia on the second hospital day in Wuhan, China. This patient received mezlocillin-sulbactam for 3 days prior to the recovery of isolate 234-49C, followed by ceftizoxime for 5 days and imipenem for 3 days. Both cases had favorable clinical outcomes.

Isolate 231-21D showed resistance or decreased susceptibility to several antimicrobials, including carbapenems, but remained susceptible to tigecycline and the polymyxins. Isolate 234-49C also exhibited resistance to several antimicrobials, remaining susceptible to aminoglycosides, fluoroquinolones, tigecycline, and polymyxins (Table 1). The isolates showed positive phenotypic screening results for the presence of MβL or Bush-Jacoby-Medeiros subgroup 2f serine β-lactamase (5). PCR and sequencing analysis identified the presence of blaKPC-2 and blaIMP-4 genes in the isolates 231-21D and 234-49C, respectively. No other Enterobacteriaceae harboring such genes were recovered from Zhejiang or Wuhan hospitals during the same period of time. Additionally, carbapenem-resistant Pseudomonas sp. and Acinetobacter sp. isolates recovered from Wuhan were also screened for MβL genes (blaIMP-like, blaVIM-like, blaSPM-1, blaSIM-1, and blaGIM-1), but positive results were not obtained, e.g., blaIMP-4.


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  		TABLE 1. Antimicrobial susceptibility profiles of K. pneumoniae clinical isolates 231-21D and 234-49C, the E. coli K-12 strain carrying the conjugative plasmid p231-21D, and the recipient E. coli K-12 strain

 
The β-lactam resistance determinant from K. pneumoniae clinical isolate 231-21D was transferred by conjugation (7). The E. coli K-12 transconjugant and the E. coli K-12 recipient strains were tested for susceptibility by using E-test strips according to the manufacturer's recommendations (AB Biodisk, Solna, Sweden). The transconjugant strain showed resistance to several β-lactams and aminoglycosides and decreased susceptibility (fourfold) to fluoroquinolones (Table 1), leading to investigations for the presence of qnr-like genes (qnrA, qnrB, and qnrS) and aac(6')-Ib-cr. PCR and sequencing detected in the index and transconjugant organisms the presence of a qnrB gene, which was identical to the qnrB4 variant found in the K. pneumoniae clinical isolate recovered from China (GenBank accession no. EF683583) (data not shown). The aac(6')-Ib-cr gene was not detected.

Analysis of plasmid content of the isolate 231-21D revealed the presence of three plasmids (60, 5, and 3.5 kb), while the transconjugant strain showed only the 60-kb plasmid. KPC-2-mediated β-lactam and QnrB-mediated quinolone resistance determinants were selftransferable and located in the 60-kb conjugative plasmid (p231-21D) (Table 1). Conjugation, transformation, and plasmid analysis of the IMP-4-producing K. pneumoniae isolate (234-49C) failed to identify a plasmid-borne location of blaIMP-4, suggesting a chromosomal location.

Although the previously reported KPC-2-producing K. pneumoniae isolate (ZR01) occurred in the same hospital 20 months earlier (13) and blaKPC-2 was also located in a 60-kb plasmid, that plasmid was not conjugative. Moreover, it did not appear to harbor the qnrB gene, since the E. coli pYW1 transformant strain did not exhibit decreased susceptibility to fluoroquinolones (13). These findings suggest that recombination events may have mobilized blaKPC-2 from the ZR01 isolate to p231-21D found in our KPC-2 strain or the gene may have been acquired elsewhere. The detection of the IMP-4-producing K. pneumoniae clinical isolate (234-49C) highlights the continued spread of this gene in this particular geographic region (Asia Pacific) and emphasizes the importance of surveillance programs (1, 9).

Such organisms represent a contemporary diagnostic challenge, because the resistance phenotype may not be obvious and could require further specialized testing. Previous studies have shown the coexistence of MβL-encoding or extended-spectrum β-lactamase-encoding genes with qnr (14). However, this report identifies the first coproduction of KPC-2 and QnrB4 encoded by resistance genes located in the same conjugative plasmid. The plasmid-mediated fluoroquinolone and β-lactam (carbapenems, cephalosporins, and penicillins) resistance determinants may spread further among clinical isolates of enteric bacilli and escalate the resistance rates for these antimicrobial classes.


   ACKNOWLEDGMENTS
 
We thank the following individuals for assistance in testing or manuscript preparation: N. O'Mara-Morrissey, D. J. Biedenbach, L. M. Deshpande, and M. J. Chen.

This study was partially funded by an educational/research grant from Wyeth.


   FOOTNOTES
 
{triangledown} Published ahead of print on 17 December 2007. Back


   REFERENCES
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 LETTER
 REFERENCES
 

  1. Bert, F., D. Vanjak, V. Leflon-Guibout, S. Mrejen, S. Delpierre, A. Redondo, and M. H. Nicolas-Chanoine. 2007. IMP-4-producing Pseudomonas aeruginosa in a French patient repatriated from Malaysia: impact of early detection and control measures. Clin. Infect. Dis. 44:764-765.[CrossRef][Medline]
  2. Bradford, P. A., S. Bratu, C. Urban, M. Visalli, N. Mariano, D. Landman, J. J. Rahal, S. Brooks, S. Cebular, and J. Quale. 2004. Emergence of carbapenem-resistant Klebsiella species possessing the class A carbapenem-hydrolyzing KPC-2 and inhibitor-resistant TEM-30 β-lactamases in New York City. Clin. Infect. Dis. 39:55-60.[CrossRef][Medline]
  3. Clinical and Laboratory Standards Institute. 2006. Methods for dilution antimicrobial susceptibility tests for bacteria that grow aerobically; approved standard M7-A7, 7th ed. CLSI, Wayne, PA.
  4. Clinical and Laboratory Standards Institute. 2007. Performance standards for antimicrobial susceptibility testing; M100-S17, 17th informational supplement. CLSI, Wayne, PA.
  5. Deshpande, L. M., R. N. Jones, T. R. Fritsche, and H. S. Sader. 2006. Occurrence and characterization of carbapenemases produced by Enterobacteriaceae: report from the SENTRY Antimicrobial Surveillance Program (2000-2004). Microb. Drug Resist. 12:223-230.[CrossRef][Medline]
  6. Mendes, R. E., K. A. Kiyota, J. Monteiro, M. Castanheira, S. S. Andrade, A. C. Gales, A. C. Pignatari, and S. Tufik. 2007. Rapid detection and identification of metallo-β-lactamase-encoding genes by multiplex real-time PCR assay and melt curve analysis. J. Clin. Microbiol. 45:544-547.[Abstract/Free Full Text]
  7. Mendes, R. E., M. A. Toleman, J. Ribeiro, H. S. Sader, R. N. Jones, and T. R. Walsh. 2004. Integron carrying a novel metallo-β-lactamase gene, blaIMP-16, and a fused form of aminoglycoside-resistant gene aac(6')-30/aac(6')-Ib': report from the SENTRY Antimicrobial Surveillance Program. Antimicrob. Agents Chemother. 48:4693-4702.[Abstract/Free Full Text]
  8. Navon-Venezia, S., I. Chmelnitsky, A. Leavitt, M. J. Schwaber, D. Schwartz, and Y. Carmeli. 2006. Plasmid-mediated imipenem-hydrolyzing enzyme KPC-2 among multiple carbapenem-resistant Escherichia coli clones in Israel. Antimicrob. Agents Chemother. 50:3098-3101.[Abstract/Free Full Text]
  9. Rossolini, G. M. 2005. Acquired metallo-β-lactamases: an increasing clinical threat. Clin. Infect. Dis. 41:1557-1558.[CrossRef][Medline]
  10. Villegas, M. V., K. Lolans, A. Correa, J. N. Kattan, J. A. Lopez, and J. P. Quinn. 2007. First identification of Pseudomonas aeruginosa isolates producing a KPC-type carbapenem-hydrolyzing β-lactamase. Antimicrob. Agents Chemother. 51:1553-1555.[Abstract/Free Full Text]
  11. Villegas, M. V., K. Lolans, A. Correa, C. J. Suarez, J. A. Lopez, M. Vallejo, and J. P. Quinn. 2006. First detection of the plasmid-mediated class A carbapenemase KPC-2 in clinical isolates of Klebsiella pneumoniae from South America. Antimicrob. Agents Chemother. 50:2880-2882.[Abstract/Free Full Text]
  12. Walsh, T. R., M. A. Toleman, L. Poirel, and P. Nordmann. 2005. Metallo-β-lactamases: the quiet before the storm? Clin. Microbiol. Rev. 18:306-325.[Abstract/Free Full Text]
  13. Wei, Z. Q., X. X. Du, Y. S. Yu, P. Shen, Y. G. Chen, and L. J. Li. 2007. Plasmid-mediated KPC-2 in a Klebsiella pneumoniae isolate from China. Antimicrob. Agents Chemother. 51:763-765.[Abstract/Free Full Text]
  14. Wu, J. J., W. C. Ko, S. H. Tsai, and J. J. Yan. 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/Free Full Text]
  15. Zhang, R., H. W. Zhou, J. C. Cai, and G. X. Chen. 2007. Plasmid-mediated carbapenem-hydrolysing β-lactamase KPC-2 in carbapenem-resistant Serratia marcescens isolates from Hangzhou, China. J. Antimicrob. Chemother. 59:574-576.[Free Full Text]
Rodrigo E. Mendes
JMI Laboratories
North Liberty, Iowa

Jan M. Bell
John D. Turnidge
Women's and Children's Hospital
Adelaide, Australia

Qiwen Yang
Peking Union Medical College Hospital
Beijing, China

Yunsong Yu
Zhejiang Medical Centre #1 Hospital
Zhejiang, China

Ziyong Sun
Wuhan Tongji Hospital
Wuhan, China

Ronald N. Jones*
JMI Laboratories
345 Beaver Kreek Centre, Suite A
North Liberty, Iowa 52317

* Phone: (319) 665-3370, Fax: (319) 655-3371, E-mail: ronald-jones{at}jmilabs.com

Antimicrobial Agents and Chemotherapy, February 2008, p. 798-799, Vol. 52, No. 2
0066-4804/08/$08.00+0     doi:10.1128/AAC.01185-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.




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