Mechanisms of linezolid resistance in staphylococci and enterococci isolated from two teaching hospitals in Shanghai, China

BMC Microbiology

Min Li¹  Xue Zou²  Bei Wang³  Yuanjun Zhu³  Tianming Li¹  Yueru Tian³ 

[1] Department of Laboratory Medicine, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China;Department of Laboratory Medicine, the Second Affiliated Hospital, Jiangxi University of Traditional Chinese Medicine, Nanchang, China;Department of Laboratory Medicine, Huashan Hospital, Shanghai Medical College, Fudan University, 12 Central Urumqi Road, Shanghai, China

关键词: Cell wall thickness;    Biofilm production;    cfr;    Mutations of 23S rRNA and ribosomal proteins;    Linezolid resistance;   

Others  :  1137724
DOI  :  10.1186/s12866-014-0292-5

 received in 2014-08-24, accepted in 2014-11-11,  发布年份 2014

【 摘 要 】

Background

Linezolid is one of the most effective treatments against Gram-positive pathogens. However, linezolid-resistant/intermediate strains have recently emerged in worldwide. The purpose of this study was to analyse the prevalence and resistance mechanisms of linezolid-resistant/intermediate staphylococci and enterococci in Shanghai, China.

Results

Thirty-two linezolid-resistant/intermediate strains, including 14 Staphylococcus capitis, three Staphylococcus aureus, 14 Enterococcus faecalis and one Enterococcus faecium clinical isolates, were collected in this study which displayed linezolid MICs of 8 to 512 μg/ml, 8–32 μg/ml, 4–8 μg/ml and 4 μg/ml, respectively. All linezolid-resistant S. capitis isolates had a novel C2131T mutation and a G2603T mutation in the 23S rRNA region, and some had a C316T (Arg106Cys) substitution in protein L4 and/or harboured cfr. Linezolid-resistant S. aureus isolates carried a C389G (Ala130Gly) substitution in protein L3, and/or harboured cfr. The cfr gene was flanked by two copies of the IS256-like element, with a downstream orf1 gene. Linezolid-resistant/intermediate enterococci lacked major resistance mechanisms. The semi-quantitative biofilm assay showed that 14 linezolid-resistant E. faecalis isolates produced a larger biofilm than linezolid-susceptible E. faecalis strains. Transmission electron microscopy showed the cell walls of linezolid-resistant/intermediate strains were thicker than linezolid-susceptible strains.

Conclusion

Our data indicated that major resistance mechanisms, such as mutations in 23S rRNA and ribosomal proteins L3 and L4, along with cfr acquisition, played an important role in linezolid resistance. Secondary resistance mechanisms, such as biofilm formation and cell wall thickness, should also be taken into account.

【 授权许可】

   
2014 Tian et al.; licensee BioMed Central Ltd.

【 图 表 】

Figure 1.

Figure 2.

Figure 3.

Figure 4.

Figure 5.

Figure 6.

Figure 7.

【 参考文献 】

• [1]Swaney SM, Aoki H, Ganoza MC, Shinabarger DL: The oxazolidinone linezolid inhibits initiation of protein synthesis in bacteria. Antimicrob Agents Chemother 1998, 42:3251-3255.
• [2]Tsiodras S, Gold HS, Sakoulas G, Eliopoulos GM, Wennersten C: Linezolid resistance in a clinical isolate of Staphylococcus aureus. Lancet 2001, 358:207-208.
• [3]Wilson P, Andrews JA, Charlesworth R, Walesby R, Singer M: Linezolid resistance in clinical isolates of Staphylococcus aureus. J Antimicrobial Chemotherapy 2003, 51:186-188.
• [4]Meka VG, Pillai SK, Sakoulas G, Wennersten C, Venkataraman L: Linezolid resistance in sequential Staphylococcus aureus isolates associated with a T2500A mutation in the 23SrRNA gene and loss of a single copy of rRNA. J Infect Dis 2004, 190:311-317.
• [5]Schwarz S, Werckenthin C, Kehrenberg C: Identification of a plasmid-borne chloramphenicol-florfenicol resistance gene in Staphylococcus sciuri. Antimicrob Agents Chemother 2000, 44:2530-2533.
• [6]Livermore DM, Warner M, Mushtaq S, North S, Woodford N: In vitro activity of the oxazolidinone RWJ-416457 against linezolid -resistant and -susceptible staphylococci and enterococci. Antimicrob Agents Chemother 2007, 51:1112-1114.
• [7]Livermore DM, Mushtaq S, Warner M, Woodford N: Activity of oxazolidinone TR-700 against linezolid -susceptible and -resistant staphylococci and enterococci. J Antimicrobial Chemotherapy 2009, 63:713-715.
• [8]Cai JC, Hu YY, Zhang R, Zhou HW, Chen GX: Linezolid-resistant clinical isolates of meticillin-resistant coagulase-negative staphylococci and Enterococcus faecium from China. J Med Microbiol 2012, 61:1568-1573.
• [9]Lincopan N, de Almeida LM, de Araújo MR E, Mamizuka EM: Linezolid resistance in Staphylococcus epidermidis associated with a G2603T mutation in the 23S rRNA gene. Int J Antimicrob Agents 2009, 34:281-282.
• [10]Kehrenberg C, Schwarz S, Jacobsen L, Hansen LH, Vester B: A new mechanism for chloramphenicol, forfenicol and clindamycin resistance: methylation of 23S ribosomal RNA at A2503. Mol Microbiol 2005, 57:1064-1073.
• [11]Long KS, Poehlsgaard J, Kehrenberg C, Schwarz S, Vester B: The Cfr rRNA methyltransferase confers resistance to phenicols, lincosamides, oxazolidinones, pleuromutilins, and streptogramin A antibiotics. Antimicrob Agents Chemother 2006, 50:2500-2505.
• [12]Locke JB, Hilgers M, Shaw KJ: Mutations in ribosomal protein L3 are associated with oxazolidinone resistance in staphylococci of clinical origin. Antimicrob Agents Chemother 2009, 53:5275-5278.
• [13]Locke JB, Hilgers M, Shaw KJ: Novel ribosomal mutations in Staphylococcus aureus strains identified through selection with the oxazolidinones Linezolid and Torezolid(TR-700). Antimicrob Agents Chemother 2009, 53:5265-5274.
• [14]Almeida LM, Araújo MR, Sacramento AG, Pavez M, Souza AG: Linezolid resistance in Brazilian Staphylococcus hominis strains is associated with L3 and 23S rRNA ribosomal mutations. Antimicrob Agents Chemother 2013, 57:4082-4083.
• [15]Costerton JW, Stewart PS, Greenberg EP: Bacterial biofilms: a common cause of persistent infections. Science 1999, 284:1318-1322.
• [16]Louis BR, x MD: Antimicrobial resistance in Gram-positive bacteria. Am J Med 2006, 119:11-19.
• [17]Wang Y, Zhang W, Wang J, Wu C, Shen Z: Distribution of the multidrug resistance gene cfr in Staphylococcus species isolates from swine farms in China. Antimicrob Agents Chemother 2012, 56:1485-1490.
• [18]Yang XJ, Chen Y, Yang Q, Qu TT, Liu LL: Emergence of cfr-harboring coagulase-negative Staphylococci among patients received linezolid therapy in two hospitals of China. J Med Microbiol 2013, 62:845-850.
• [19]Chen H, Wu W, Ni M, Liu Y, Zhang J: Linezolid-resistant clinical isolates of enterococci and Staphylococcus cohnii from a multicentre study in China: molecular epidemiology and resistance mechanisms. Int J Antimicrob Agents 2013, 42:317-321.
• [20]Performance Standards for Antimicrobial Susceptibility Testing; 23rd Informational Supplement M100-S23. CLSI, Wayne, PA, USA; 2013.
• [21]Enright MC, Spratt BG: Multilocus sequence typing. Trends Microbiol 1999, 7:482-487.
• [22]Nallapareddy SR, Duh RW, Singh KV, Murray BE: Molecular typing of selected Enterococcus faecalis isolates: pilot study using multilocus sequence typing and pulsed-field gel electrophoresis. J Clin Microbiol 2002, 40:868-876.
• [23]Homan WL, Tribe D, Poznanski S, Li M, Hogg G: Multilocus sequence typing scheme for Enterococcus faecium. J Clin Microbiol 2002, 40:1963-1971.
• [24]Aanensen DM, Spratt BG: The multilocus sequence typing network: mlst.net. Nucleic Acids Res 2005, 33:728-733.
• [25]Arias CA, Panesso D, Singh KV, Rice LB, Murray BE: Cotransfer of antibiotic resistance genes and a hylEfm-containing virulence plasmid in Enterococcus faecium. Antimicrob Agents Chemother 2009, 10:4240-4246.
• [26]Mendes RE, Deshpande LM, Farrell DJ, Spanu T, Fadda G: Assessment of linezolid resistance mechanisms among Staphylococcus epidermidis causing bacteraemia in Rome, Italy. J Antimicrobial Chemotherapy 2010, 65:2329-2335.
• [27]Toh SM, Xiong L, Arias CA, Villegas MV, Lolans K: Acquisition of a natural resistance gene renders a clinical strain of methicillin-resistant Staphylococcus aureus resistant to the synthetic antibiotic linezolid. Mol Microbiol 2007, 64:1506-1514.
• [28]Besier S, Ludwig A, Zander J, Brade V, Wichelhaus TA: Linezolid resistance in Staphylococcus aureus: gene dosage effect, stability, fitness costs, and cross-resistances. Antimicrob Agents Chemother 2008, 52:1570-1572.
• [29]Marshall SH, Donskey CJ, Hutton-Thomas R, Salata RA, Rice LB: Gene dosage and linezolid resistance in Enterococcus faecium and Enterococcus faecalis. Antimicrob Agents Chemother 2002, 10:3334-3336.
• [30]Schneider CA, Rasband WS, Eliceiri KW: NIH Image to ImageJ: 25 years of image analysis. Nat Methods 2012, 9:671-675.
• [31]Román F, Roldán C, Trincado P, Ballesteros C, Carazo C: Detection of linezolid-resistant Staphylococcus aureus with 23S rRNA and novel L4 riboprotein mutations in a cystic fibrosis patient in Spain. Antimicrob Agents Chemother 2013, 57:2428-2429.
• [32]Mendes RE, Hogan PA, Streit JM, Jones RN, Flamm RK: Zyvox(R) Annual Appraisal of Potency and Spectrum (ZAAPS) Program: report of linezolid activity over 9 years (2004–12). J Antimicrobial Chemotherapy 2014, 69:1582-1588.
• [33]Gu B, Kelesidis T, Tsiodras S, Hindler J, Humphries RM: The emerging problem of linezolid-resistant Staphylococcus. J Antimicrobial Chemotherapy 2013, 68:4-11.
• [34]Flamm RK, Mendes RE, Ross JE, Sader HS, Jones RN: An international activity and spectrum analysis of linezolid: ZAAPS Program results for 2011. Diagn Microbiol Infect Dis 2013, 76:206-213.