- Email: [email protected]
Vancomycin-resistant enterococci remain rare in New Zealand
Vancomycin-resistant enterococci remain rare in New Zealand Helen Heffernan • BSc (Hons) Scientist, Antibiotic Reference Laboratory, Communicable Disease Group Institute of Environmental Science and Research (ESR), Wellington, NZ Tim Blackmore • FRACP FRCPA PhD Infectious Disease Physician and Microbiologist Institute of Environmental Science and Research (ESR),Wellington, NZ Capital and Coast Health District Health Board, Wellington, NZ
Abstract Vancomycin resistance in Enterococcus faecalis and E. faecium (VREF) has been closely monitored in New Zealand (NZ) following the emergence of VREF in other countries. Diagnostic laboratories are requested to submit all probable isolates of VREF for reference testing, which includes confirmation of antimicrobial susceptibility, van gene PCR, and pulsed-field gel electrophoresis (PFGE) typing. A total of 17 VREF isolates from 15 patients were confirmed between 1996, when the first isolate was identified, and 2002. Two different strains of VREF were isolated from each of two patients. The 15 patients were from several areas throughout NZ. E. faeca/is with the vanA genotype was most common, being isolated from 12 patients. Of the three PFGE patterns identified among the vanA-positive E. faecalis isolates, one pattern was predominant (11 of 13 isolates). VanB-positive E. faecalis was isolated from one patient and vanA-positive E.faecium were isolated from the remaining two patients. Available data indicate that at least one third of the VREF isolated were clinically significant and the majority of patients had one or more risk factors for VREF. Only two patients were colonised or infected with VREF resistant to amoxicillin. These data indicate that VREF are rare in NZ, and the predominance of one strain of vanA-positive E. faecalis suggests a widespread environmental reservoir of the strain.
Introduction Vancomycin resistance in Enterococcus faecalis and E. faecium (VREF) has been closely monitored in New Zealand (NZ) following the emergence of VREF in other countries. VREF are included in the antibiotic-resistant bacteria monitoring scheme (ARBMS), a national surveillance programme which monitors rare and emerging resistant organisms. This paper describes confirmed isolates of VREF in NZ between 1996, when the first isolate was identified, and the end of 2002.
Methods As part of the ARBMS, hospital and community microbiology laboratories throughout NZ are requested to submit all probable isolates of VREF to the communicable disease reference centre at the Institute of Environmental Science and Research (ESR), for confirmation and further epidemiological investigation. Additional clinical information is requested when a VREF is confirmed. This information includes underlying condition, clinical significance of the isolate, antibiotic treatment history, history of previous admissions to hospital, and recent overseas travel history.
Australian Infection Control
At ESR, Rapid ID 32 Strep kits [bioMerieux SA, Marcy-l'Etoile, France], with an additional test for acid formation in methyl 0.D-glucopyranoside (MGP), were used to confirm the enterococcal species. Where these results were ambiguous, peR, based on the amplification of genes encoding Dalanine:D-alanine ligases, was used to identify the species 1. Vancomycin, teicoplanin, ampicillin, gentamIcIn and ciprofloxacin minimum inhibitory concentrations (MrCs) were determined by Etest [AB Biodisk, Solna, SwedenJ on MuellerHinton agar and interpreted according to NCCLS breakpoints. Beta-Iactamase activity was tested using nitrocefin [Glaxo, Greenford, EnglandJ. The vancomycin resistance genotype was determined by a multiplex PCR assay that combines primer sets for the vanA, vanB and vane genes 2. Confirmed VREF were typed by DNA macrorestriction analysis, using pulsed-field gel electrophoresis [PFGE using a CHEF Mapper, Biorad, Richmond, California, United StatesJ after digestion with the enzyme SmaI, and interpreted according to the criteria proposed by Tenover et al' . For the analyses presented in this paper, duplicate VREF isolates from the same patient were excluded, unless they were distinguishable on the basis of PFGE typing.
•
Volume 8
Issue 3
September 2003
Figure 1.
Results
VREF isolations in NZ, 1996-2002.
A total of 17 VREF isolates from 15 patients were confirmed between 1996 and 2002. The patients were from four of the
O A..ckland
five main centres in NZ: Auckland (five patients), Hamilton
. Hamilton
(three), Wellington (one) and Christchurch (six) (Figure 1).
!lW&llington ~ CllriSlcllufch
Characterisation of VREF isolates E. faecalis with the vanA genotype was isolated from 12 (80%) of the 15 patients (Table 1). VanB-positive E. faecalis was isolated from one patient and vanA-positive E. faecium were isolated from the remaining two patients.
Three PFGE patterns were identified among the VQI1Apositive E. faecalis isolates (Table 1). One pattern (designated A) was most common and was identified from 11 of the 12 patients with vanA-positive E. faecalis. All but two of the vanA-positive E. faecalis isolates had this pattern. This strain was isolated in all four centres where VREF ha ve been identified in NZ and was isolated in 4 of the 5 years in which VREF have been isolated. Isolates with two different PFGE patterns (A and B) were isolated from one of the 12 patients with vanA-positive E. faecal is. Similarly, two distinct vanApositive E. faecium isolates (PFGE patterns C and D) were isolated from another patient.
• • ""
".,
..
,"
, ~,
I
'"''
Clinical details
The clinical details, as reported by the referring institution, are summarised in Table 2. Full clinical details were not received for all cases. At least one third of the isolates were clinically significant, and wounds and urine were the most common types of specimen. As would be expected, most patients had received antibiotics prior to identification of VREF, although only three were known to have received vancomycin, all for treatment of peritonitis associated with chronic ambulatory peritoneal dialysis. Of the 13 patients for whom risk factors were recorded, all had at least one risk
Antimicrobial resistance All isolates had vancomycin MICs of >256 mg /L. The vallApositive isolates had teicoplanin MICs of 32 to >256 mg/L and the vanB-positive isolate had a teicoplanin MIC of 0.5
factor described, although the majority of pa tients would not have been predicted to be at risk for VREF carriage or infection in the NZ setting.
mg / L. All 14 E. faecalis isolates were susceptible to ampicillin
Discussion
and only two had high-level gentamicin resistance (MIC
The small number of VREF identified through the national ARBMS surveillance programme suggests that VREF are still rare in the NZ population. Moreover, due to the
>1024 mg /L). The three E.faecium isolates were resistant to
both ampicillin (MIC >256 mg /L) and high-level gentamicin.
Table 1. Species
E. faecalis
E. faecium
t
t
VREF isolated in NZ, 1996-2002 van gene
PFGE " pattern
No. of patients
Years isolated
Centres
vanA
A
11'
1996,1999, 2000 & 2001
Auckland, Hamilton, Wellington & Christchurch
B
l'
1999
Christchurch
E
1
2001
Christchurch
vanB
Z
1
1999
Christchurch
vanA
C
2'
1998 & 2001
Auckland & Hamilton
D
l'
2001
Auckland
In.·house PFGE pattern. designations Isolates with PFGE patterns A and B were isolated from the same patient Isolates with PFGE patterns C and D were isolated from the same patient
Australian Infection Control
Volume 8
Issue 3
September 2003
predominance of E. jaecalis among the VREF, all but three isolates remained susceptible to amoxicillin, meaning that in most cases treatment difficulty would only occur if the patient was allergic to penicillin. Most hospitals in NZ are not routinely screening high-risk or other patients for VREF. Among those hospitals that do screen, the protocols vary. These protocois include screening all faeces submitted for Clostridillm difficile toxin testing, screening specimens from patients in transplant and oncology units, screening patients with other multiresistant organisms, and more comprehensive point-prevalence surveys. The majority of laboratories routinely test the vancomycin susceptibility of clinically significant isolates of E. faecalis and E. faecium. These procedures are consistent with current recommendations for screening for multiresistant organisms 4,
Table 2.
Clinical infonnation on patients wit!J VREF, as received from the referring institution. Number
Site'" Abscess / wound Urine Faeces CAPD fluid Nose
7 4
The results of four point-prevalence surveys conducted in NZ between 1995 and 2001 have been published ~ . These surveys tested the vancomycin susceptibility of enterococci isolated from clinical samples and also screened for bowel carriage among hospital patients at risk of VREF. No patients with VREF were identified in the first three surveys 5-1, and two patients with VREF were identified in the last survey in 2001 B, These data clearly indicate that VREF are rare in NZ and there does not appear to be any significant cross-transmission in NZ healthcare settings, This is in spite of rising rates of multiresistant MRSA (mMRSA) infection in several parts of the country, including a multicentre outbreak in 1999-2000 in the lower North Island of a mMRSA strain which was associated with diarrhoea and faecal carriage 9, to, The increasing rates of rnMRSA in many NZ healthcare facilities suggest that infection control standards alone are Wllikely to account for our low rate of VREF. We speculate that the low rate of VREF may be due to two factors, First, there may not have been frequent enough introductions of VREF into the hospital and residential-care facility environment for the organisms to establish themselves. Second, VREF strains with epidemic potential may not have been introduced into clinical areas under circumstances which would favour their spread.
3 2
Now Available
1
2% CHG'· 70% IPA dose delivered swabs and swabsticks
Clinical significance t
5
Yes No
6
Unknown
4
Recent previous antibiotics Broad-spectrum Vancomycin None Unknown
4 3 3 5
Clinical risk factors Dialysis - Chronic ambulatory peritoneal dialysis - Home dialysis Surgical wound infection or colonisa hon Indwelling urinary catheter Chronic leg ulcer Malignancy Recent overseas travel None reported t
3 1
5 2 2 2 2 2
Refers to the a/Ultomica/ site from which tlu! 17 VREF isowtes were obtained Subjective assessment tnilde by one author (TB) Ofl the basis of the clinirol
injomUJtion provided and the site from wllicll tile VREF was isolated
Austral1an Infection Control
SOLU-Iv" swabs (medium & large): ./ Insertion of peripheral cannulae ./ Blood culture collections
SOLU-IV- 5wabsticks: ./ Insertion of peripheral catheters ,/ Catheter site-care ./ Antisepsis of a 10em x 10em site ./ Peel pack for sterile - handling
SOLU-IV MAXI' swabsticks: ./ Insertion of all catheters ./ Antisepsis of a 30cm x 30cm site ./ Peel pack for sterile - handling
For 0""'" and enqu"," In Austr.l'Medic81 Spec:ialties Australia pty Lld Phone: (02)94177955
I \ J I~: '
MEDICAL
=~,cm1,au
SPECIALTIES AU"~ALI "
'a.-..."""'_d_C--·_-...ax:_~'.2\XI2MII.~'''''''RR·'O
VolumeS
Issue 3
September 2003
Not only have there been few isolations of VREF in NZ, but those that have been identified are predominantly E. faecalis.
•
worthwhile to routinely screen high-risk patients for VREF
carriage at this stage in NZ is debatable, but it is clear that all
This contrasts with the situation in the United States (US),
clinically significant isolates of enterococci should be tested
Europe and Australia, where vancomycin resistance is mainly
for vancomycin resistance. It is also clear that, once present in
identified in E. faecium 11.13. For example, in NZ, E. faecalis has
the hospital environment, VREF are notoriously difficult to
accounted for 82% (95% Cl 57-96%) of the VREF identified,
control.
whereas, in the US, E. faecalis was reported to account for only 17% (95% Cl 15-19%) of VREF between 1995 and 1997
14
•
This
difference is likely to be attributable to nosocomial outbreaks
References 1.
Dutka-Malen S, Evers S & Courvalin P. Detection of glycopeptide resistance genotypes and identification to the species level of clinically relevant enterococci. J Clin Microbiol 1995; 33:24-27.
2.
Clarke Ne, Cooksley RC, Hill BC et al. Characterisation of glycopeptide-resistant enterococci from US hospitals. Antimicrob Agents Chemother 1993; 37:2311-2317.
3.
Tenover Fe, Arbeit RD, Goering RV et al. Interpreting chromosomal DNA restriction patterns produced by pulsed-field gel electrophoresis: criteria for bacterial strain typing. J Clin Microbiol1995; 33:2233-2239.
4.
Current approaches to screening for multiresistant organisms (MRO) in acute care Australian and selected New Zealand hospitals and recommendations for a minimum standard. Aust Infect Control 2002; 7:viii-xii.
5.
Antibiotic resistance among enterococci. NZ Public Health Rep 1996; 3:21.
6.
Taylor SL, Pottumarthy S, Wong CGS et al. Surveillance for antimicrobial resistance in enterococci. NZ Med J 1997; 110:251253.
7.
Kobayashi K, Rao M, Keis S et al. Enterococci with reduced susceptibility to vancomycin in New Zealand. J Antimicrob Chemother 2000; 46:405-410.
8.
Briggs S, Upton A, Bilkey M et al. Vancomycin-resistant enterococcal colonisation of hospitalised patients in Auckland. NZ Med J 2002; 115. URL:http://www.nzma.org.nz/journal! 115-1160/145/
9.
Epidemiology of multiresistant methicillin-resistant Staphylococcus aureus. Lab Link 2000; 7:8-9.
of vancomycin-resistant E. faecium in the US. In NZ, the ratio of E. faecalis to E. faecium among VREF (14:3) is quite similar to that among vancomycin-susceptible isolates. For example, during a similar time period in Wellington Hospital, 37 blood stream infections were caused by E. faecalis compared with four caused by E. faecium [unpublished data]. There were no known links between any of the 15 patients from whom VREF were isolated, in spite of 11 of these patients having an indistinguishable strain of vanA-positive E. faecal is. This predominance of a single strain, which has
been isolated from patients in geographically diverse areas of NZ over a period of 6 years, suggests there may be a widespread environmental reservoir of the strain. Notably, the same strain appears to be common among VREF isolated from poultry in NZ. The glycopeptide avoparcin was used extensively in the poultry industry in NZ before its withdrawal in 2000. Among 82 VREF isolated from poultry faecal samples during the 2000-01 period, 73 were vanApositive E. faecalis with the remainder being vanA-positive E. faecium 15. All the vancomycin-resistant E. faecalis poultry isolates had indistinguishable or closely related PFGE patterns to each other and to the predominant strain isolated from humans. The small number of human VREF isolates identified in NZ makes it difficult to draw conclusions about the source of vancomycin resistance in enterococci. It would be interesting to examine the PFGE patterns of vancomycin-susceptible E.
faecalis isolates to determine how much clonal variation there is among this species and whether the PFGE pattern of the predominant vancomycin-resistant strain is also common among susceptible isolates. There is also a need to further study the relatedness of human and poultry VREF isolates. There was no systematic analysis of food consumption among the 15 patients from whom VREF were isolated. NZ is in an advantageous position because it has such a low rate of VREF. This suggests that it is still worthwhile taking a 'search and destroy' approach to infection control when inpatients with VREF are identified 16. Whether or not it is
Australian Infection Control
10. Multiresistant methicillin-resistant Staphylococcus aureus. Lab Link 2001; 8:10-11. 11. Mundy LM, Sahm DF & Gilmore M. Relationships between enterococcal virulence and antimicrobial resistance. Clin Microbiol Rev 2000; 13:513-522. 12. Schouten MA, Hoogkamp-Korstanje JAA, Meis JFG et al. Prevalence of vancomycin-resistant enterococci in Europe. Eur J Clin Microbial Infect Dis 2000; 19:816-822. 13. Bell J, Turnidge J & Coombs G. Emergence and epidemiology of vancomycin-resistant enterococci in Australia. Commun Dis Intell 1998; 22:249-252. 14. Huycke MM, Sahm DF, Gilmore MS. Multiple-drug resistant enterococci: the nature of the problem and an agenda for the future. Emerg Infect Dis 1998; 4:239-249. 15. Manson JM, Keis S, Smith JMB et al. A clonal lineage of vanA-type Enterococcus faecalis predominates in vancomycin-resistant enterococci isolated in New Zealand. Antimicrob Agents Chemother 2003; 47:204-210. 16. Mayhall CG. Control of vancomycin-resistant enterococci: it is important, it is possible, and it is cost effective [editorial]. Infect Cont Hosp Epid 2002; 23:420-423.
-~.~-
Volume 8
Issue 3
September 2003
Abstract Vancomycin resistance in Enterococcus faecalis and E. faecium (VREF) has been closely monitored in New Zealand (NZ) following the emergence of VREF in other countries. Diagnostic laboratories are requested to submit all probable isolates of VREF for reference testing, which includes confirmation of antimicrobial susceptibility, van gene PCR, and pulsed-field gel electrophoresis (PFGE) typing. A total of 17 VREF isolates from 15 patients were confirmed between 1996, when the first isolate was identified, and 2002. Two different strains of VREF were isolated from each of two patients. The 15 patients were from several areas throughout NZ. E. faeca/is with the vanA genotype was most common, being isolated from 12 patients. Of the three PFGE patterns identified among the vanA-positive E. faecalis isolates, one pattern was predominant (11 of 13 isolates). VanB-positive E. faecalis was isolated from one patient and vanA-positive E.faecium were isolated from the remaining two patients. Available data indicate that at least one third of the VREF isolated were clinically significant and the majority of patients had one or more risk factors for VREF. Only two patients were colonised or infected with VREF resistant to amoxicillin. These data indicate that VREF are rare in NZ, and the predominance of one strain of vanA-positive E. faecalis suggests a widespread environmental reservoir of the strain.
Introduction Vancomycin resistance in Enterococcus faecalis and E. faecium (VREF) has been closely monitored in New Zealand (NZ) following the emergence of VREF in other countries. VREF are included in the antibiotic-resistant bacteria monitoring scheme (ARBMS), a national surveillance programme which monitors rare and emerging resistant organisms. This paper describes confirmed isolates of VREF in NZ between 1996, when the first isolate was identified, and the end of 2002.
Methods As part of the ARBMS, hospital and community microbiology laboratories throughout NZ are requested to submit all probable isolates of VREF to the communicable disease reference centre at the Institute of Environmental Science and Research (ESR), for confirmation and further epidemiological investigation. Additional clinical information is requested when a VREF is confirmed. This information includes underlying condition, clinical significance of the isolate, antibiotic treatment history, history of previous admissions to hospital, and recent overseas travel history.
Australian Infection Control
At ESR, Rapid ID 32 Strep kits [bioMerieux SA, Marcy-l'Etoile, France], with an additional test for acid formation in methyl 0.D-glucopyranoside (MGP), were used to confirm the enterococcal species. Where these results were ambiguous, peR, based on the amplification of genes encoding Dalanine:D-alanine ligases, was used to identify the species 1. Vancomycin, teicoplanin, ampicillin, gentamIcIn and ciprofloxacin minimum inhibitory concentrations (MrCs) were determined by Etest [AB Biodisk, Solna, SwedenJ on MuellerHinton agar and interpreted according to NCCLS breakpoints. Beta-Iactamase activity was tested using nitrocefin [Glaxo, Greenford, EnglandJ. The vancomycin resistance genotype was determined by a multiplex PCR assay that combines primer sets for the vanA, vanB and vane genes 2. Confirmed VREF were typed by DNA macrorestriction analysis, using pulsed-field gel electrophoresis [PFGE using a CHEF Mapper, Biorad, Richmond, California, United StatesJ after digestion with the enzyme SmaI, and interpreted according to the criteria proposed by Tenover et al' . For the analyses presented in this paper, duplicate VREF isolates from the same patient were excluded, unless they were distinguishable on the basis of PFGE typing.
•
Volume 8
Issue 3
September 2003
Figure 1.
Results
VREF isolations in NZ, 1996-2002.
A total of 17 VREF isolates from 15 patients were confirmed between 1996 and 2002. The patients were from four of the
O A..ckland
five main centres in NZ: Auckland (five patients), Hamilton
. Hamilton
(three), Wellington (one) and Christchurch (six) (Figure 1).
!lW&llington ~ CllriSlcllufch
Characterisation of VREF isolates E. faecalis with the vanA genotype was isolated from 12 (80%) of the 15 patients (Table 1). VanB-positive E. faecalis was isolated from one patient and vanA-positive E. faecium were isolated from the remaining two patients.
Three PFGE patterns were identified among the VQI1Apositive E. faecalis isolates (Table 1). One pattern (designated A) was most common and was identified from 11 of the 12 patients with vanA-positive E. faecalis. All but two of the vanA-positive E. faecalis isolates had this pattern. This strain was isolated in all four centres where VREF ha ve been identified in NZ and was isolated in 4 of the 5 years in which VREF have been isolated. Isolates with two different PFGE patterns (A and B) were isolated from one of the 12 patients with vanA-positive E. faecal is. Similarly, two distinct vanApositive E. faecium isolates (PFGE patterns C and D) were isolated from another patient.
• • ""
".,
..
,"
, ~,
I
'"''
Clinical details
The clinical details, as reported by the referring institution, are summarised in Table 2. Full clinical details were not received for all cases. At least one third of the isolates were clinically significant, and wounds and urine were the most common types of specimen. As would be expected, most patients had received antibiotics prior to identification of VREF, although only three were known to have received vancomycin, all for treatment of peritonitis associated with chronic ambulatory peritoneal dialysis. Of the 13 patients for whom risk factors were recorded, all had at least one risk
Antimicrobial resistance All isolates had vancomycin MICs of >256 mg /L. The vallApositive isolates had teicoplanin MICs of 32 to >256 mg/L and the vanB-positive isolate had a teicoplanin MIC of 0.5
factor described, although the majority of pa tients would not have been predicted to be at risk for VREF carriage or infection in the NZ setting.
mg / L. All 14 E. faecalis isolates were susceptible to ampicillin
Discussion
and only two had high-level gentamicin resistance (MIC
The small number of VREF identified through the national ARBMS surveillance programme suggests that VREF are still rare in the NZ population. Moreover, due to the
>1024 mg /L). The three E.faecium isolates were resistant to
both ampicillin (MIC >256 mg /L) and high-level gentamicin.
Table 1. Species
E. faecalis
E. faecium
t
t
VREF isolated in NZ, 1996-2002 van gene
PFGE " pattern
No. of patients
Years isolated
Centres
vanA
A
11'
1996,1999, 2000 & 2001
Auckland, Hamilton, Wellington & Christchurch
B
l'
1999
Christchurch
E
1
2001
Christchurch
vanB
Z
1
1999
Christchurch
vanA
C
2'
1998 & 2001
Auckland & Hamilton
D
l'
2001
Auckland
In.·house PFGE pattern. designations Isolates with PFGE patterns A and B were isolated from the same patient Isolates with PFGE patterns C and D were isolated from the same patient
Australian Infection Control
Volume 8
Issue 3
September 2003
predominance of E. jaecalis among the VREF, all but three isolates remained susceptible to amoxicillin, meaning that in most cases treatment difficulty would only occur if the patient was allergic to penicillin. Most hospitals in NZ are not routinely screening high-risk or other patients for VREF. Among those hospitals that do screen, the protocols vary. These protocois include screening all faeces submitted for Clostridillm difficile toxin testing, screening specimens from patients in transplant and oncology units, screening patients with other multiresistant organisms, and more comprehensive point-prevalence surveys. The majority of laboratories routinely test the vancomycin susceptibility of clinically significant isolates of E. faecalis and E. faecium. These procedures are consistent with current recommendations for screening for multiresistant organisms 4,
Table 2.
Clinical infonnation on patients wit!J VREF, as received from the referring institution. Number
Site'" Abscess / wound Urine Faeces CAPD fluid Nose
7 4
The results of four point-prevalence surveys conducted in NZ between 1995 and 2001 have been published ~ . These surveys tested the vancomycin susceptibility of enterococci isolated from clinical samples and also screened for bowel carriage among hospital patients at risk of VREF. No patients with VREF were identified in the first three surveys 5-1, and two patients with VREF were identified in the last survey in 2001 B, These data clearly indicate that VREF are rare in NZ and there does not appear to be any significant cross-transmission in NZ healthcare settings, This is in spite of rising rates of multiresistant MRSA (mMRSA) infection in several parts of the country, including a multicentre outbreak in 1999-2000 in the lower North Island of a mMRSA strain which was associated with diarrhoea and faecal carriage 9, to, The increasing rates of rnMRSA in many NZ healthcare facilities suggest that infection control standards alone are Wllikely to account for our low rate of VREF. We speculate that the low rate of VREF may be due to two factors, First, there may not have been frequent enough introductions of VREF into the hospital and residential-care facility environment for the organisms to establish themselves. Second, VREF strains with epidemic potential may not have been introduced into clinical areas under circumstances which would favour their spread.
3 2
Now Available
1
2% CHG'· 70% IPA dose delivered swabs and swabsticks
Clinical significance t
5
Yes No
6
Unknown
4
Recent previous antibiotics Broad-spectrum Vancomycin None Unknown
4 3 3 5
Clinical risk factors Dialysis - Chronic ambulatory peritoneal dialysis - Home dialysis Surgical wound infection or colonisa hon Indwelling urinary catheter Chronic leg ulcer Malignancy Recent overseas travel None reported t
3 1
5 2 2 2 2 2
Refers to the a/Ultomica/ site from which tlu! 17 VREF isowtes were obtained Subjective assessment tnilde by one author (TB) Ofl the basis of the clinirol
injomUJtion provided and the site from wllicll tile VREF was isolated
Austral1an Infection Control
SOLU-Iv" swabs (medium & large): ./ Insertion of peripheral cannulae ./ Blood culture collections
SOLU-IV- 5wabsticks: ./ Insertion of peripheral catheters ,/ Catheter site-care ./ Antisepsis of a 10em x 10em site ./ Peel pack for sterile - handling
SOLU-IV MAXI' swabsticks: ./ Insertion of all catheters ./ Antisepsis of a 30cm x 30cm site ./ Peel pack for sterile - handling
For 0""'" and enqu"," In Austr.l'Medic81 Spec:ialties Australia pty Lld Phone: (02)94177955
I \ J I~: '
MEDICAL
=~,cm1,au
SPECIALTIES AU"~ALI "
'a.-..."""'_d_C--·_-...ax:_~'.2\XI2MII.~'''''''RR·'O
VolumeS
Issue 3
September 2003
Not only have there been few isolations of VREF in NZ, but those that have been identified are predominantly E. faecalis.
•
worthwhile to routinely screen high-risk patients for VREF
carriage at this stage in NZ is debatable, but it is clear that all
This contrasts with the situation in the United States (US),
clinically significant isolates of enterococci should be tested
Europe and Australia, where vancomycin resistance is mainly
for vancomycin resistance. It is also clear that, once present in
identified in E. faecium 11.13. For example, in NZ, E. faecalis has
the hospital environment, VREF are notoriously difficult to
accounted for 82% (95% Cl 57-96%) of the VREF identified,
control.
whereas, in the US, E. faecalis was reported to account for only 17% (95% Cl 15-19%) of VREF between 1995 and 1997
14
•
This
difference is likely to be attributable to nosocomial outbreaks
References 1.
Dutka-Malen S, Evers S & Courvalin P. Detection of glycopeptide resistance genotypes and identification to the species level of clinically relevant enterococci. J Clin Microbiol 1995; 33:24-27.
2.
Clarke Ne, Cooksley RC, Hill BC et al. Characterisation of glycopeptide-resistant enterococci from US hospitals. Antimicrob Agents Chemother 1993; 37:2311-2317.
3.
Tenover Fe, Arbeit RD, Goering RV et al. Interpreting chromosomal DNA restriction patterns produced by pulsed-field gel electrophoresis: criteria for bacterial strain typing. J Clin Microbiol1995; 33:2233-2239.
4.
Current approaches to screening for multiresistant organisms (MRO) in acute care Australian and selected New Zealand hospitals and recommendations for a minimum standard. Aust Infect Control 2002; 7:viii-xii.
5.
Antibiotic resistance among enterococci. NZ Public Health Rep 1996; 3:21.
6.
Taylor SL, Pottumarthy S, Wong CGS et al. Surveillance for antimicrobial resistance in enterococci. NZ Med J 1997; 110:251253.
7.
Kobayashi K, Rao M, Keis S et al. Enterococci with reduced susceptibility to vancomycin in New Zealand. J Antimicrob Chemother 2000; 46:405-410.
8.
Briggs S, Upton A, Bilkey M et al. Vancomycin-resistant enterococcal colonisation of hospitalised patients in Auckland. NZ Med J 2002; 115. URL:http://www.nzma.org.nz/journal! 115-1160/145/
9.
Epidemiology of multiresistant methicillin-resistant Staphylococcus aureus. Lab Link 2000; 7:8-9.
of vancomycin-resistant E. faecium in the US. In NZ, the ratio of E. faecalis to E. faecium among VREF (14:3) is quite similar to that among vancomycin-susceptible isolates. For example, during a similar time period in Wellington Hospital, 37 blood stream infections were caused by E. faecalis compared with four caused by E. faecium [unpublished data]. There were no known links between any of the 15 patients from whom VREF were isolated, in spite of 11 of these patients having an indistinguishable strain of vanA-positive E. faecal is. This predominance of a single strain, which has
been isolated from patients in geographically diverse areas of NZ over a period of 6 years, suggests there may be a widespread environmental reservoir of the strain. Notably, the same strain appears to be common among VREF isolated from poultry in NZ. The glycopeptide avoparcin was used extensively in the poultry industry in NZ before its withdrawal in 2000. Among 82 VREF isolated from poultry faecal samples during the 2000-01 period, 73 were vanApositive E. faecalis with the remainder being vanA-positive E. faecium 15. All the vancomycin-resistant E. faecalis poultry isolates had indistinguishable or closely related PFGE patterns to each other and to the predominant strain isolated from humans. The small number of human VREF isolates identified in NZ makes it difficult to draw conclusions about the source of vancomycin resistance in enterococci. It would be interesting to examine the PFGE patterns of vancomycin-susceptible E.
faecalis isolates to determine how much clonal variation there is among this species and whether the PFGE pattern of the predominant vancomycin-resistant strain is also common among susceptible isolates. There is also a need to further study the relatedness of human and poultry VREF isolates. There was no systematic analysis of food consumption among the 15 patients from whom VREF were isolated. NZ is in an advantageous position because it has such a low rate of VREF. This suggests that it is still worthwhile taking a 'search and destroy' approach to infection control when inpatients with VREF are identified 16. Whether or not it is
Australian Infection Control
10. Multiresistant methicillin-resistant Staphylococcus aureus. Lab Link 2001; 8:10-11. 11. Mundy LM, Sahm DF & Gilmore M. Relationships between enterococcal virulence and antimicrobial resistance. Clin Microbiol Rev 2000; 13:513-522. 12. Schouten MA, Hoogkamp-Korstanje JAA, Meis JFG et al. Prevalence of vancomycin-resistant enterococci in Europe. Eur J Clin Microbial Infect Dis 2000; 19:816-822. 13. Bell J, Turnidge J & Coombs G. Emergence and epidemiology of vancomycin-resistant enterococci in Australia. Commun Dis Intell 1998; 22:249-252. 14. Huycke MM, Sahm DF, Gilmore MS. Multiple-drug resistant enterococci: the nature of the problem and an agenda for the future. Emerg Infect Dis 1998; 4:239-249. 15. Manson JM, Keis S, Smith JMB et al. A clonal lineage of vanA-type Enterococcus faecalis predominates in vancomycin-resistant enterococci isolated in New Zealand. Antimicrob Agents Chemother 2003; 47:204-210. 16. Mayhall CG. Control of vancomycin-resistant enterococci: it is important, it is possible, and it is cost effective [editorial]. Infect Cont Hosp Epid 2002; 23:420-423.
-~.~-
Volume 8
Issue 3
September 2003