Ann Lab Med.  2012 Jan;32(1):38-43. 10.3343/alm.2012.32.1.38.

Expression of Sme Efflux Pumps and Multilocus Sequence Typing in Clinical Isolates of Stenotrophomonas maltophilia

• Cho HH
• Sung JY
• Kwon KC
• Koo SH

• KMID: 1781436
• DOI: http://doi.org/10.3343/alm.2012.32.1.38

Abstract

BACKGROUND
Stenotrophomonas maltophilia has emerged as an important opportunistic pathogen, which causes infections that are often difficult to manage because of the inherent resistance of the pathogen to a variety of antimicrobial agents. In this study, we analyzed the expressions of smeABC and smeDEF and their correlation with antimicrobial susceptibility. We also evaluated the genetic relatedness and epidemiological links among 33 isolates of S. maltophilia.
METHODS
In total, 33 S. maltophilia strains were isolated from patients in a tertiary hospital in Daejeon. Minimum inhibitory concentrations (MICs) of 11 antimicrobial agents were determined by using agar dilution method and E-test (BioMerieux, France). Real-time PCR analysis was performed to evaluate the expression of the Sme efflux systems in the S. maltophilia isolates. Additionally, an epidemiological investigation was performed using multilocus sequence typing (MLST) assays.
RESULTS
The findings of susceptibility testing showed that the majority of the S. maltophilia isolates were resistant to beta-lactams and aminoglycosides. Twenty-one clinical isolates overexpressed smeABC and showed high resistance to ciprofloxacin. Moreover, a high degree of genetic diversity was observed among the S. maltophilia isolates; 3 sequence types (STs) and 23 allelic profiles were observed.
CONCLUSIONS
The smeABC efflux pump was associated with multidrug resistance in clinical isolates of S. maltophilia. In particular, smeABC efflux pumps appear to perform an important role in ciprofloxacin resistance of S. maltophilia. The MLST scheme for S. maltophilia represents a discriminatory typing method with stable markers and is appropriate for studying population structures.

Keyword

Stenotrophomonas maltophilia; smeABC; smeDEF; Efflux pump; MLST

MeSH Terms

Alleles
Anti-Infective Agents/pharmacology
Bacterial Proteins/genetics/*metabolism
Bacterial Typing Techniques
Ciprofloxacin/pharmacology
Drug Resistance, Multiple, Bacterial
Gene Expression Regulation, Bacterial
Gram-Negative Bacterial Infections/microbiology
Humans
Microbial Sensitivity Tests
Multilocus Sequence Typing
Stenotrophomonas maltophilia/classification/drug effects/*genetics/isolation & purification

Figure

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  Fig. 1 A phylogenetic tree of the concatenated nucleotide sequences of 7 housekeeping genes (atpD, gapA, guaA, mutM, nuoD, ppsA, and recA) of S. maltophilia obtained using the NJ method with Kimura 2 correction for distance calculations. Group A and A' isolates were highly resistant to ciprofloxacin and overexpressed smeB, and Group B isolates were highly resistant to ceftazidime and cefepime.

Reference

1. Hu LF, Chang X, Ye Y, Wang ZX, Shao YB, Shi W, et al. Stenotrophomonas maltophilia resistance to trimethoprim/sulfamethoxazole mediated by acquisition of sul and dfrA genes in a plasmid-mediated class 1 integron. Int J Antimicrob Agents. 2011. 37:230–234.

2. Liaw SJ, Lee YL, Hsueh PR. Multidrug resistance in clinical isolates of Stenotrophomonas maltophilia: roles of integrons, efflux pumps, phosphoglucomutase (SpgM), and melanin and biofilm formation. Int J Antimicrob Agents. 2010. 35:126–130.

3. San Gabriel P, Zhou J, Tabibi S, Chen Y, Trauzzi M, Saiman L. Antimicrobial susceptibility and synergy studies of Stenotrophomonas maltophilia isolates from patients with cystic fibrosis. Antimicrob Agents Chemother. 2004. 48:168–171.

4. Falagas ME, Valkimadi PE, Huang YT, Matthaiou DK, Hsueh PR. Therapeutic options for Stenotrophomonas maltophilia infections beyond cotrimoxazole: a systematic review. J Antimicrob Chemother. 2008. 62:889–894.

5. Valdezate S, Vindel A, Martín-Dávila P, Del Saz BS, Baquero F, Cantón R. High genetic diversity among Stenotrophomonas maltophilia strains despite their originating at a single hospital. J Clin Microbiol. 2004. 42:693–699.

6. Li XZ, Zhang L, Poole K. SmeC, an outer membrane multidrug efflux protein of Stenotrophomonas maltophilia. Antimicrob Agents Chemother. 2002. 46:333–343.

7. Chang LL, Chen HF, Chang CY, Lee TM, Wu WJ. Contribution of integrons, and smeABC and SmeDEF efflux pumps to multidrug resistance in clinical isolates of Stenotrophomonas maltophilia. J Antimicrob Chemother. 2004. 53:518–521.

8. Nicodemo AC, Araujo MR, Ruiz AS, Gales AC. In vitro susceptibility of Stenotrophomonas maltophilia isolates: comparison of disc diffusion, Etest and agar dilution methods. J Antimicrob Chemother. 2004. 53:604–608.

9. Kaiser S, Biehler K, Jonas D. A Stenotrophomonas maltophilia multilocus sequence typing scheme for inferring population structure. J Bacteriol. 2009. 191:2934–2943.

10. Foley SL, Lynne AM, Nayak R. Molecular typing methodologies for microbial source tracking and epidemiological investigations of gram-negative bacterial foodborne pathogens. Infect Genet Evol. 2009. 9:430–440.

11. Schaumann R, Laurin F, Rodloff AC. Molecular typing of clinical isolates of Stenotrophomonas maltophilia by pulsed-field gel electrophoresis and random primer PCR fingerprinting. Int J Hyg Environ Health. 2008. 211:292–298.

12. National Committee for Clinical Laboratory Standards. Approved standard NCCLS document M7-A6. Methods for dilution antimicrobial susceptibility test for bacteria that grow aerobically. 2003. 6th ed. Wayne, PA: CLSI.

13. Clinical and Laboratory Standards Institute. Performance standards for antimicrobial susceptibility testing; twentieth informational supplement M100-S20. 2010. Wayne, PA: Clinical and Laboratory Standards Institute.

14. Denton M, Kerr KG. Microbiological and clinical aspects of infection associated with Stenotrophomonas maltophilia. Clin Microbiol Rev. 1998. 11:57–80.

15. Lee K, Chang CL, Lee NY, Kim HS, Hong KS, Cho HC. Korean nationwide surveillance of antimicrobial resistance of bacteria in 1998. Yonsei Med J. 2000. 41:497–506.

16. Lee H, Kim CK, Lee J, Lee SH, Ahn JY, Hong SG, et al. Antimicrobial resistance of clinically important bacteria isolated from 12 hospitals in Korea in 2005 and 2006. Korean J Clin Microbiol. 2007. 10:59–69.

17. Jang KS, Oh JY, Kang HY, Jin JS, Seol SY, Kim J, et al. Genetic diversity of Stenotrophomonas maltophilia isolated from clinical specimens. J Bacteriol Virol. 2007. 37:79–89.

18. Poole K. Efflux-mediated multiresistance in gram-negative bacteria. Clin Microbiol Infect. 2004. 10:12–26.

19. Quale J, Bratu S, Gupta J, Landman D. Interplay of efflux system, ampC, and oprD expression in carbapenem resistance of Pseudomonas aeruginosa clinical isolates. Antimicrob Agents Chemother. 2006. 50:1633–1641.

20. Zhang L, Li XZ, Poole K. Multiple antibiotic resistance in Stenotrophomonas maltophilia: involvement of a multidrug efflux system. Antimicrob Agents Chemother. 2000. 44:287–293.

21. Alonso A, Morales G, Escalante R, Campanario E, Sastre L, Martinez JL. Overexpression of the multidrug efflux pump SmeDEF impairs Stenotrophomonas maltophilia physiology. J Antimicrob Chemother. 2004. 53:432–434.

22. Gould VC, Avison MB. SmeDEF-mediated antimicrobial drug resistance in Stenotrophomonas maltophilia clinical isolates having defined phylogenetic relationships. J Antimicrob Chemother. 2006. 57:1070–1076.

23. Song JH, Sung JY, Kwon KC, Park JW, Cho HH, Shin SY, et al. Analysis of acquired resistance genes in Stenotrophomonas maltophilia. Korean J Lab Med. 2010. 30:295–300.

24. Top J, Willems R, van der Velden S, Asbroek M, Bonten M. Emergence of clonal complex 17 Enterococcus faecium in the Netherlands. J Clin Microbiol. 2008. 46:214–219.

25. Cho HH, Sung JY, Kwon KC, Lim JS, Koo SH. Antimicrobial resistance and multilocus sequence typing of vancomycin-resistant Enterococcus faecium isolated from the Chungcheong area. Korean J Clin Microbiol. 2011. 14:60–66.