Antimicrobial Resistance Genes of Vancomycin-Resistant Enterococci at Phramongkutklao Hospital

Main Article Content

Jatapat Hemapanpairoa
Wichai Santimaleeworagun
Dhitiwat Changpradub
Sudaluck Thunyaharn


Enterococci infection is a serious medical problem due to resistance to many antimicrobial agents, including vancomycin. The most common of vancomycin resistant genes in Thailand were vanA and vanB, mainly vanA. Data on drug resistance genes of vancomycin-resistant enterococci in Thailand are not specific to those infected, lack of up-to-date information and studied only the vancomycin resistance gene. The purpose of this study was to determine the pattern of antimicrobial resistant genes in VRE at Phramongkutklao Hospital. Methods: Bacterial isolates obtained from patients with VRE infections between 1 January, 2014, and 1 April, 2018 at Phramongkutklao Hospital were reviewed. Clonal relationships were assessed by random amplified polymorphic DNA analysis and identified resistance genes of representative pathogens with whole genome sequencing analysis. Results: Forty-nine of the VRE strains were E. faecium. They were classified in seven groups according to amplified DNA bands. The predominant patterns were pattern A (55.1%) and pattern E was 26.53%. There was only one isolate in each group (D, F, G). Of the 7 representative VRE strains studied for their vancomycin resistance patterns, 4 strains were vanHAX gene. The VRE isolates tested were universally susceptible to linezolid and linezolid resistant gene was not detected. Conclusion: VRE were susceptible to linezolid. The majority of gene was vanA, found on plasmid and chromosome. Spread of vancomycin resistance genes to other persons can be prevented by standard and contact precaution.

Article Details

Pharmaceutical Practice


Barbier N, Saulnier P, Chachaty E, Dumontier S, Andremont A. Random amplified polymorphic DNA typing versus pulsed-field gel electrophoresis for epidemiological typing of vancomycin-resistant enterococci. J Clin Microbiol. 1996;34(5):1096-9.

Bender JK, Cattoir V, Hegstad K, Sadowy E, Coque TM, Westh H, et al. Update on prevalence and mechanisms of resistance to linezolid, tigecycline and daptomycin in enterococci in Europe: Towards a common nomenclature. Drug Resistance Updates. 2018;40:25-39.

Cattoir V, Isnard C, Cosquer T, Odhiambo A, Bucquet F, Guérin F, et al. Genomic analysis of reduced susceptibility to tigecycline in Enterococcus faecium. Antimicrob Agents Chemother. 2015;59(1):239-44.

Centers for Disease Control and Prevention. 2019 AR Threat Report [online]. 2021 Nov 23 [cited 2022 May 5]. Available from: 2019.

Chen C, Xu X, Qu T, Yu Y, Ying C, Liu Q, et al. Prevalence of the fosfomycin-resistance determinant, fosB3, in Enterococcus faecium clinical isolates from China. J Med Microbiol. 2014;63(Pt 11):1484-9.

Chotiprasitsakul D, Santanirand P, Thitichai P, Rotjanapan P, Watcharananan S, Siriarayapon P, et al. Epidemiology and control of the first reported vancomycin-resistant enterococcus outbreak at a tertiary-care hospital in Bangkok, Thailand. Southeast Asian J Trop Med Public Health. 2016;47(3):494-502.

Clinical and Laboratory Standards Institute (CLSI). Performance Standards for Antimicrobial Susceptibility Testing; Twenty-eight information supplement. CLSI document M100. Wayne, PA. 2018.

de Almeida LM, de Araújo MR, Iwasaki MF, Sacramento AG, Rocha D, da Silva LP, et al. Linezolid resistance in vancomycin-resistant Enterococcus faecalis and Enterococcus faecium isolates in a Brazilian hospital. Antimicrob Agents Chemother. 2014;58(5):2993-4.

Drug And Medical Supply Information Center, Ministry of Public Health, 2016. National Strategic Plan on Antimicrobial Resistance 2017-2021 Thailand [Internet]. 2022 [cited 5 May 2022] Available from:

European Committee on Antimicrobial Susceptibility Testing. Breakpoint tables forMICs and zone diameters interpretation of January 1,2019 [Internet]. 2019 [cited 3 June 2019]. Available from:

Gold HS. Vancomycin-resistant enterococci: mechanisms and clinical observations. Clin Infect Dis. 2001;33(2):210-9.

Hayden MK, Blom DW, Lyle EA, Moore CG, Weinstein RA. Risk of Hand or Glove Contamination After Contact With Patients Colonized With Vancomycin-Resistant Enterococcus or the Colonized Patients' Environment. Infection Control & Hospital Epidemiology. 2008;29(2):149-54.

Hollenbeck BL, Rice LB. Intrinsic and acquired resistance mechanisms in enterococcus. Virulence. 2012;3(5):421-33.

Miller WR, Arias CA, Murray BE. Enterococcal Infections. In: Loscalzo J, Fauci A, Kasper D, Hauser S, Longo D, Jameson JL, editors. Harrison's Principles of Internal Medicine, 21e. New York, NY: McGraw-Hill Education; 2022.

National Antimicrobial Resistance Surveillance Center, Thailand. Antimicrobial Resistance 2000-2021. [online]. [cited 5 May. 2021]. Available from:

Nilgate S, Nunthapisud P, Chongthaleong A. Vancomycin-resistant enterococci in King Chulalongkorn Memorial Hospital: a 5-year study. J Med Assoc Thai. 2003;86 (Suppl 2):S224-9.

O'Driscoll T, Crank CW. Vancomycin-resistant enterococcal infections: epidemiology, clinical manifestations, and optimal management. Infect Drug Resist. 2015;8:217-30.

Saengsuwan P, Singkhamanan K, Madla S, Ingviya N, Romyasamit C. Molecular epidemiology of vancomycin-resistant Enterococcus faecium clinical isolates in a tertiary care hospital in southern Thailand: a retrospective study. PeerJ. 2021;9:e11478.

Thongkoom P, Kanjanahareutai S, Chantrakooptungool S, Rahule S. Vancomycin-resistant enterococci (VRE) isolates isolated in Rajavithi Hospital between 1999 and 2009. J Med Assoc Thai. 2012;95 (Suppl 3):S7-15. WHO publishes list of bacteria for which new antibiotics are urgently needed [Internet]. 2017. [cited 3 June 2019]. Available from: WHO.

Xu X, Chen C, Lin D, Guo Q, Hu F, Zhu D, et al. The fosfomycin resistance gene fosB3 is located on a transferable, extrachromosomal circular intermediate in clinical Enterococcus faecium isolates. PLoS One. 2013;8(10):e78106.