Skip directly to site content Skip directly to page options Skip directly to A-Z link Skip directly to A-Z link Skip directly to A-Z link
Volume 6, Number 5—October 2000
Dispatch

Fecal Colonization with Vancomycin-Resistant Enterococci in Australia

Article Metrics
33
citations of this article
EID Journal Metrics on Scopus
Author affiliations: *Monash Medical Centre, Melbourne, Australia; †Monash University, Melbourne, Australia

Cite This Article

Abstract

To assess the rate of fecal vancomycin-resistant enterococci (VRE) colonization in Australia, we examined specimens from 1,085 healthy volunteers. VRE was cultured from 2 (0.2%) of 1,085 specimens; both were vanB Enterococcus faecium, identical by pulsed-field gel electrophoresis, but with a pattern rare in Melbourne hospitals.

Colonization and infection with vancomycin-resistant enterococci (VRE) are emerging worldwide. In Europe, agricultural use of the glycopeptide growth promoter avoparcin has been implicated in the emergence of vanA VRE in the food chain (1), and fecal colonization rates of 2%-28% have been reported in some communities (2,3). In the United States, where avoparcin is not used, both vanA and vanB VRE strains appear to be largely nosocomially spread, with fecal VRE colonization rare in nonhospitalized patients (4,5). By contrast, in Australia, where avoparcin has been used widely (10,000 kg/year) in agriculture for many years (6) and the per capita consumption of antibiotics is one of the highest in the world (7), VRE (mostly vanB [8]) has only recently emerged as an important nosocomial pathogen. We assessed the rate of fecal VRE colonization in a population of healthy Australians.

The Study

In mid-1997, fecal specimens from 1,085 healthy volunteers were collected and frozen at -70°C as baseline specimens for a water quality study in Melbourne, Australia. These previously described (9) volunteers were from 294 families with young children who lived in a lower to middle-class suburb. They were specifically chosen because they were representative of young Australian families in eating habits and medical care. Thus, the elderly, the unmarried, and the very poor were not represented. Study participants had no history of diarrhea or antibiotic use at the time of specimen collection.

For VRE screening, frozen samples were thawed and spread onto enterococcosal agar (BBL Microbiology Systems, Cockeysville, MD) containing 6 µg/ml vancomycin and incubating at 35°C for 48-72 hours. Each sample was also incubated in enterococcosal broth (BBL) without vancomycin for 48 hours, prior being spread onto enterococcosal agar containing 6 µg/ml vancomycin. From esculin-positive colonies, three of each morphologic appearance were selected from the direct agar and the subcultured enterococcosal broth cultures of each specimen and provisionally identified as either Enterococcus faecium or E. faecalis by routine criteria (gram-positive cocci, L-pyrrolidonyl-β-naphthylamide hydrolase-positive, nonmotile, catalase-negative, and pigment-negative) (10,11). All isolates fulfilling these criteria were assessed for susceptibility to vancomycin and teicoplanin by the E-test method (AB Biodisk, Dalvagen, Sweden). Isolates with an MIC to vancomycin ≥2 µg/ml were analyzed for the presence of vanA, B, C1, or C2/3 genes by polymerase chain reaction; if vanA- or vanB-positive, they were then confirmed as either E. faecium or E. faecalis by automated biochemical analysis (BioMerieux Vitek Inc., MO) and by polymerase chain reaction, and were assessed by pulsed-field gel electrophoresis (PFGE) (8,12,13).

To be certain that this analysis of frozen specimens was a valid assessment of the rate of fecal VRE carriage in this population, two additional studies were conducted. First, to verify that -70°C storage did not affect the overall recovery of enterococci, a randomly selected subset of 112 of the 1,085 specimens were cultured on enterococcosal agar (BBL) without antibiotic and assessed for enterococci by routine identification techniques (10,11). In addition, to assess whether -70°C storage could selectively impair recovery of VRE, fresh fecal specimens were spiked with concentrations (104-108/ml) of isolates of E. faecalis (vanA, n=1, vanB, n=2) or E. faecium (vanA, n=2; vanB, n=2), then stored at -70°C for 2 weeks before being thawed and cultured.

Results

Enterococci were identified in 106 of the subset of 112 specimens, a rate consistent with previous reports (14). VRE were also consistently recovered from our frozen spiked specimens. These findings suggest that -70°C storage of specimens does not affect the recovery of enterococci in general, or VRE in particular.

In the community study, VRE was isolated from 2 (0.2%) of the 1,085 (95% confidence intervals 0%-0.4%) specimens. Both isolates were vanB E. faecium and were detected in both agar and broth cultures. E-test MIC results at 24 hours for both isolates were 12 µg/ml for vancomycin and 0.125 µg/ml for teicoplanin. Although they were identical by PFGE, they displayed a PFGE pattern that is uncommon among VRE isolates from Melbourne hospitals. The two participants who were vanB E.faecium positive were not related. One was a 34-year-old man and the other a 30-year-old woman; both were married, and each had two children. None of the other family members had detectable fecal VRE colonization. The man had a history of stable ulcerative colitis and was receiving sulfasalazine.

Conclusions

This study suggests that fecal colonization with VRE is present but uncommon in Australia. Despite widespread agricultural use of avoparcin and high community rates of antibiotic use, vanA E. faecium was not identified. vanB E. faecium, which is the most common clinical VRE strain in Australia (8) and whose nosocomial transmission remains a concern (15), was identified in healthy Australians.

Dr. Padiglione is an infectious diseases physician at the Monash Medical Centre and a member of the Department of Epidemiology and Preventative Medicine, Monash University, Melbourne, Australia.

Top

Acknowledgments

The authors thank the staff at the Microbiological Diagnostic Unit, University of Melbourne, for the PFGE analysis.

Funding for this project was provided by the Department of Infectious Diseases and Clinical Epidemiology, Monash Medical Centre.

Top

References

  1. Wegener  HC, Aarestrup  FM, Jensen  LB, Hammerum  AM, Bager  F. Use of antimicrobial growth promoters in food animals and Enterococcus faecium resistance to therapeutic antimicrobial drugs in Europe. Emerg Infect Dis. 1999;5:32935. DOIPubMedGoogle Scholar
  2. Endtz  HP, van den Braak  N, van Belkum  A, Kluytmans  JA, Koeleman  JG, Spanjaard  L, Faecal carriage of vancomycin-resistant enterococci in hospitalized patients and those living in the community in the Netherlands. J Clin Microbiol. 1997;35:302631.PubMedGoogle Scholar
  3. Van der Auwera  P, Pensart  N, Korten  V, Murray  BE, Leclercq  R. Influence of oral glycopeptides on the fecal flora of human volunteers: selection of highly glycopeptide-resistant enterococci. J Infect Dis. 1996;173:112936.PubMedGoogle Scholar
  4. Coque  T, Tomayko  JF, Ricke  SC, Okhyusen  PC, Murray  BE. Vancomycin-resistant enterococci from nosocomial community and animal sources in the United States. Antimicrob Agents Chemother. 1996;40:26059.PubMedGoogle Scholar
  5. Eliopoulos  GM. Vancomycin-resistant enterococci: Mechanism and clinical relevance. Infect Dis Clin North Am. 1997;11:85165. DOIPubMedGoogle Scholar
  6. Report of the Joint Expert Technical Advisory Committee on Antibiotic Resistance (JETACAR). The use of antibiotics in food-producing animals: antibiotic-resistant bacteria in animals and humans. Australia: Commonwealth Department of Health and Aged Care. Commonwealth Department of Agriculture, Fisheries and Forestry. Australia; 1999.
  7. McManus  P, Mammond  ML, Whicker  SD, Primrose  JG, Mant  A, Fairall  SR. Antibiotic use in the Australian community, 1990-1995. Med J Aust. 1997;167:1247.PubMedGoogle Scholar
  8. Bell  JM, Paton  JC, Turnidge  J. Emergence of vancomycin-resistant enterococci in Australia: phenotypic and genotypic characteristics of isolates. J Clin Microbiol. 1998;36:218790.PubMedGoogle Scholar
  9. Hellard  ME, Sinclair  MI, Hogg  GG, Fairley  CK. Prevalence of enteric pathogens among community based asymptomatic individuals. J Gastroenterol Hepatol. 2000;15:2903. DOIPubMedGoogle Scholar
  10. Facklam  RR, Collins  MD. Identification of Enterococcus species isolated from human infections by a conventional test scheme. J Clin Microbiol. 1989;27:7314.PubMedGoogle Scholar
  11. Facklam  RR, Sahm  DF, Teixeira  LM. Enterococcus. In: Murray PR, Baron EJ, Pfaller MA, Tenover FC, Yolken YH, editors. Manual of clinical microbiology - 1999. Washington: American Society for Microbiology;1999. p. 297-305.
  12. Dutka-Malen  A, Evers  S, Courvalin  P. Detection of glycopeptide resistance genotypes and identification to the species level of clinically relevant enterococci by PCR. J Clin Microbiol. 1995;33:247.PubMedGoogle Scholar
  13. Miranda  AG, Singh  KV, Murray  BE. DNA fingerprinting of Enterococcus faecium by pulsed-field gel electrophoresis may be a useful epidemiologic tool. J Clin Microbiol. 1991;29:27527.PubMedGoogle Scholar
  14. Murray  BE. The life and times of the Enterococcus. Clin Microbiol Rev. 1990;3:4665.PubMedGoogle Scholar
  15. Grayson  M, Grabsch  EA, Johnson  PDR, Olden  D, Aberline  M, Li  HY, Outcome of a screening program for vancomycin-resistant enterococci (VRE) in a University Teaching Hospital. Med J Aust. 1999;171:1336.PubMedGoogle Scholar

Top

Cite This Article

DOI: 10.3201/eid0605.000514

Table of Contents – Volume 6, Number 5—October 2000

EID Search Options
presentation_01 Advanced Article Search – Search articles by author and/or keyword.
presentation_01 Articles by Country Search – Search articles by the topic country.
presentation_01 Article Type Search – Search articles by article type and issue.

Top

Comments

Please use the form below to submit correspondence to the authors or contact them at the following address:

Alexander Padiglione, Infectious Diseases & Clinical Epidemiology Department, Monash Medical Centre, 246 Clayton Rd., Clayton, Victoria, Australia 3168; fax: +61-3-9594-4533

Send To

10000 character(s) remaining.

Top

Page created: December 17, 2010
Page updated: December 17, 2010
Page reviewed: December 17, 2010
The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.
file_external