Department of Clinical Microbiology, Central Hospital, SE-351 85 Växjö, Sweden
Received 11 March 2002; returned 20 June 2002; revised 10 August 2002; accepted 3 October 2002
![]() |
Abstract |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
![]() |
Introduction |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
However, no international comparison of magnitude has been made and no survey has looked at the resistance levels in bacteria from women with acute uncomplicated UTI. The aim of the ECO·SENS study was to remedy this and to ascertain whether there is a difference in antimicrobial resistance in community strains of Escherichia coli among European countries. Furthermore, the overall antimicrobial resistance of other uropathogens (Proteus mirabilis, Klebsiella spp., other Enterobacteriaceae, Staphylococcus saprophyticus, enterococci and Pseudomonas spp.) was determined. The preliminary results, restricted to E. coli and comprising less than half the final number of isolates, have been published previously.7 This report presents the complete results from the ECO·SENS survey.
![]() |
Materials and methods |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
A total of 252 community care centres in 16 European countries (listed in Table 1) and Canada enrolled patients. Wherever possible, the centres within a country were chosen to represent two or three geographically separate areas.
|
In total, 4734 women between 18 and 65 years of age with symptoms of uncomplicated lower UTI were eligible for inclusion. Patients who had had symptoms for >7 days, those who had had more than three episodes in the previous 12 months, and those who had received oral or systemic antibiotics or been hospitalized during the 2 weeks before the onset of symptoms were excluded. Patients with upper UTI, pregnant patients and patients with urinary tract abnormalities or other complicating factors were also excluded. The severity of symptoms (i.e. frequency, dysuria, urgency and suprapubic pain) was rated and scored on a four-point scale (absent, 0; mild, 1; moderate, 2; severe, 3) and only patients with a total symptom score (maximum 12) of 2 or more were included.
Urine sampling procedures
The urine cultures were carried out only for the purposes of this study. Patients were required to provide a freshly voided midstream urine sample. Immediately after sampling, the urine was tested for leucocytes using a Multistix 2 reagent strip for urinalysis (Bayer Corporation, Diagnostics Division, Elkhart, IN, USA); results were recorded as negative, trace, +, ++ or +++, as instructed by the manufacturer. A Uricult dip-slide (Orion Diagnostica, Espoo, Finland) was prepared according to the manufacturers instructions and, without prior incubation, immediately forwarded by courier to a central laboratory for incubation, quantification and idenification. All isolates were stored at 70°C and susceptibility tests carried out batch-wise in one laboratory.
Quantitative assessment
On the day of receipt, the Uricult dip-slide was incubated at 37°C at the central laboratory. After 1620 h it was compared with a chart developed by Orion Diagnostica for quantitative assessment of the dip-slides, and the number of cfu/mL recorded (<103, 103 to <105 or
105). Urine samples were classified as positive or negative in accordance with the guidelines for testing issued by the Infectious Diseases Society of America (IDSA).8 A positive test was defined as a urine sample containing between
103 and <105 cfu/mL and presence of pyuria or a sample containing
105 cfu/mL irrespective of the presence of pyuria. Pyuria was defined as trace or more as determined with the Multistix 2 method. For the purposes of this report, all isolates with bacterial counts of
103 cfu/mL were included irrespective of the presence of pyuria.
Identification
All bacteria occurring in urine samples at 103 cfu/mL were identified by their biochemical reaction profile using APIU identification products (bioMérieux, Marcy lÉtoile, France). In the case of mixed cultures, no more than two bacteria (those with the two highest counts) were identified. Bacteria occurring at <103 cfu/mL were not identified. Identified bacteria were stored on microbeads at 70°C.
The following bacteria were classified as uropathogens: E. coli, Klebsiella spp., Proteus spp., Enterobacter spp., Citrobacter spp., other Enterobacteriaceae, S. saprophyticus, enterococci and Pseudomonas spp. In this report, the pathogens are grouped into the following categories: E. coli, Proteus mirabilis, Klebsiella spp., other Enterobacteriaceae, S. saprophyticus and other pathogens (enterococci and Pseudomonas spp.).
Antimicrobial susceptibility testing
The antimicrobial susceptibility of bacteria was determined using the disc diffusion method as described by the Swedish Reference Group for Antibiotics (SRGA).9 Isosensitest agar and antibiotic discs were obtained from Oxoid Limited (Basingstoke, UK). Inhibition zone diameters were measured to the nearest millimetre with a slide gauge. E. coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853 were used as control strains. Test results were only accepted when inhibition zone diameters of the control strains were within performance ranges (published on http://www.srga.org).
All bacteria were tested against the following antimicrobial agents: ampicillin, co-amoxiclav, mecillinam, cefadroxil, trimethoprim and sulfamethoxazole (alone and in combination), ciprofloxacin, nalidixic acid, nitrofurantoin, fosfomycin and gentamicin. Disc strengths, zone diameter breakpoints and corresponding MIC breakpoints were published in the interim report.7 In the case of mixed culture, only the major pathogen was tested.
Statistical methods
The statistical significance tests of differences between countries with regard to age and symptom score were carried out using analysis of variance including country as an effect in the model. To adjust for multiple comparisons, the method of Tukey was used. The distribution of each pathogen by age group was tested by two-tailed 2 tests.
![]() |
Results |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Recognized uropathogens were cultured from 3278 (69.2%) patients, the incidence of proven infection ranging from 88.2% in Luxembourg (only 34 patients) to 54.3% in Germany. The most common pathogen was E. coli (53.3% of all patients), followed by P. mirabilis (Table 2). Infection with P. mirabilis was significantly more common in patients over 50 years (P < 0.001) and infections with S. saprophyticus were significantly more common in younger patients (P < 0.001) (Table 3). Infection with recognized uropathogens was associated with leucocyturia in 95% or more of cases (Table 2). E. coli was the predominant pathogen in all countries (mean 77.0%, range 52.9% in Portugal to 86.4% in Norway). P. mirabilis infection appeared to be most common in Portugal and Greece (16.9% and 11.6% of infections, respectively) as was Klebsiella spp. infection (7.6% and 6.8% of infections, respectively). In contrast, UTI due to P. mirabilis or Klebsiella spp. was seldom encountered in Denmark, Finland, Norway and Sweden (combined incidence 3.06.4% of infections). S. saprophyticus infection appeared to be particularly common in Ireland and Sweden (6.7% and 8.2% of infections, respectively).
|
|
|
|
|
Of the 2478 E. coli, 1447 (58.4%) were susceptible to all 12 agents tested, the greatest incidences being in Sweden (72.2%), Finland (71.9%), Denmark (68.2%), Austria (67.5%) and Norway (66.6%), the lowest being in Spain (30.9%), Ireland (40.9%) and Portugal (43.0%). Resistance to five or more antimicrobials occurred in 4.3% whereas resistance to seven or more drugs was rare at 0.8% and was seen predominantly in Spain (10 of the 21 isolates).
Despite the large number of patients enrolled in the study, the number of isolates of species other than E. coli did not permit country-wise analysis of the data. Table 5 shows the overall antimicrobial resistance in P. mirabilis, Klebsiella spp., other Enterobacteriaceae and S. saprophyticus. Notable is the high ampicillin and trimethoprim resistance in P. mirabilis.
![]() |
Discussion |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
The major strengths of the ECO·SENS survey are the number of European countries involved, the short enrolment period, the efforts made to obtain bacteria from outside the hospital and bacteria freed from repeated antibiotic medication, and the uniformity of species identification and of susceptibility testing, thereby guaranteeing uniformity of results. Furthermore, the E. coli quantitative raw data from the susceptibility tests are available to the reader7 demonstrating that the breakpoints used to categorize the strains into S, I and R were equally appropriate in all participating countries and that there were no problems of breakpoints dividing homogeneous biological populations.
The major weakness of the ECO·SENS study is its temporal limits. The 2 year enrolment period (1999 and 2000) did not permit analysis of resistance development over time. A further weakness is that we have so far not had the possibility to determine the degree of clonal heterogeneity of the 2478 E. coli (still in a freezer), as recently done in the USA by Manges et al.10 for E. coli with trimethoprim/sulfamethoxazole resistance.
The overall frequency of infection and the pathogens involved were broadly as expected and confirm the validity of the survey. E. coli was the most common pathogen, exceeding 70% of proven infections in all countries except Portugal and Greece. P. mirabilis was the second most common pathogen and along with Klebsiella spp. appeared more commonly in southern Europe than in the Nordic countries. S. saprophyticus seemed particularly common in Sweden (8.2% of all pathogens as compared with a mean 3.7%). The frequency of infection with specific pathogens has been shown to change over time11 and with S. saprophyticus there is a pronounced seasonality in the Nordic countries.12,13 However, the length of the enrolment period should have prevented this possible bias.
Comparison of the results from the ECO·SENS survey with resistance rates previously published for the same geographical area, but involving more limited bacterial populations, different methodology and other breakpoints, shows a broadly similar picture,1,3,11,1418 but there are notable exceptions.
In comparison with a recent French study,17 the ECO·SENS survey shows broadly corresponding figures for resistance in E. coli to ampicillin (amoxicillin) (41.3% versus 27.6%), trimethoprim/sulfamethoxazole (21.8% versus 15.1%), nalidixic acid (8.1% versus 3.5%) and fosfomycin (0.9% versus 1.0%), but considerably lower figures for resistance to co-amoxiclav (36.7% versus 1.5%). This is related to the fact that the SRGA breakpoints for these drugs consistently label ordinary TEM1-producing E. coli in UTIs as available to therapy with the combination. A recent study from Wales18 reports consistently higher figures of resistance for coliforms than our study does for E. coli in the UKfor ampicillin 53.2% versus 37.2%, co-amoxiclav 8.4% versus 2.8%, trimethoprim 26.3% versus 13.3%, and for ciprofloxacin 2.2 versus 0.6%. When one compares E. coli with other coliforms as shown in Table 5, it is evident that incomplete species identification will radically skew resistance frequencies. Overall, P. mirabilis were less resistant to ampicillin and more resistant to trimethoprim than E. coli, whereas Klebsiella spp. were significantly more resistant to ampicillin, nitrofurantoin and fosfomycin. The other Enterobacteriaceae were much more often resistant to the broad spectrum ß-lactams (ampicillin, co-amoxiclav and cephalosporins), nitrofurantoin and fosfomycin. Thus, even minor differences in the materials fraction of Klebsiella spp. will significantly influence the resistance to ß-lactams. A small difference in the fraction of P. mirabilis or Klebsiella spp. will significantly skew the resistance to nitrofurantoin and fosfomycin, etc. The time worn difference in breakpoints between European countries or the tradition of expressing antimicrobial resistance as a composite result for a number of species may be of less importance when susceptibility tests are used within a therapeutic tradition to predict the outcome of therapy in a single patient, but severely interfere with our possibilities to compare frequencies of antimicrobial resistance between geographical areas and to compare schemes of counter measures for decreasing antimicrobial resistance development.
The European Antimicrobial Resistance Surveillance System (EARSS) now report resistance frequencies in invasive E. coli on its website (see URL http://www.earss.rivm.nl). For drugs that can be compared (i.e. ampicillin, ciprofloxacin and gentamicin), the differences between the EARSS data and the ECO·SENS data are minor and the ranking of countries is identical. For example, both materials show ampicillin resistance in Spain and Portugal at 50% and in Sweden at
20% and ciprofloxacin resistance in Spain at
15% and in the Scandinavian countries <5%.
It is interesting to note how S. saprophyticus, apart from being inherently insensitive to mecillinam, fosfomycin and nalidixic acid, exhibited almost no resistance development to the agents tested. The pronounced seasonality, at least in temperate climates, in the appearance of this uropathogen, indicates a yearly contribution of fresh clones from ecosystems not overloaded with antimicrobial agents.12
Surveys of antimicrobial resistance form the basis for decisions on empirical therapy. The ECO·SENS study clearly shows that E. coli is now resistant to ampicillin in >40% of cases in Spain, Portugal, Ireland and Luxembourg, to sulfamethoxazole in >40% in Ireland, Portugal and Spain, and to trimethoprim and trimethoprim/sulfamethoxazole in >20% of cases in Germany, Ireland, Portugal and Spain. The results indicate that it is time to seriously reconsider the empirical use of these antibiotics in many countries, or to seriously investigate at which level of resistance the outcome of therapy with these antibiotics is influenced, or to develop clear strategies to counteract further resistance development to these drugs. To the best of our knowledge none have been done so far. The IDSA has published recommendations on therapy of uncomplicated acute bacterial cystitis and has ranked the efficacy of commonly used antimicrobials.19 The ranking was carried out on the strength and quality of the published evidence for efficacy in the treatment of infections caused by susceptible bacteria, but did not take into account the possible failure of empirical therapy due to antimicrobial resistance or the need for strategies to counteract further resistance development. There have been previous reports of increased quinolone resistance in Spain and concern about increasing resistance elsewhere.5,6,20 The level of quinolone resistance in Spain and Portugal (in the present study >20% ciprofloxacin resistance when measured with a breakpoint designed to discover emerging ciprofloxacin resistance, and 27% when measured with nalidixic acid as a means to discover all quinolone resistance) and the yearly gradual increase in other countries, albeit at a lower level,20 reinforce the caution advocated concerning the use of quinolones in uncomplicated infections.20,21
A striking finding in the ECO·SENS survey is the low incidence of resistance to agents used only in lower UTI. Mecillinam, fosfomycin and nitrofurantoin have been used for >25 years and exhibit equally low levels of resistance in countries that have used them extensively and in countries that have not used them. The importance of co-selection is illustrated by sulfamethoxazole resistance in Sweden and Denmark (16.6% versus 21.2%); the frequencies are very similar despite the fact that sulphonamides were abandoned in Sweden in the 1970s but are still extensively used in the treatment of UTIs in Denmark. However, trimethoprim is used extensively in Sweden and co-selects for sulphonamide resistance.16
In conclusion, the ECO·SENS survey has shown that it is time to reconsider the empirical use of ampicillin and sulphonamides in UTIs since resistance in E. coli in several areas in Europe is 40% and of trimethoprim and trimethoprim/sulfamethoxazole since resistance is
20%, or to investigate seriously at which levels of resistance the outcome of therapy with these antibiotics is influenced. Increasing quinolone resistance in community E. coli, primarily in Spain and Portugal, is a cause for immediate action, one of which should be to severely curtail quinolone use in uncomplicated infections.20,21 We have not been able to find evidence that this is occurring. The continued low levels of resistance to co-amoxiclav, cefadroxil, mecillinam, nitrofurantoin and fosfomycin in almost all areas of Europe and in Canada should be taken into account when new therapeutic strategies are formed. Most of these drugs have no other place in infection therapy, which makes them suitable for use in uncomplicated lower UTIs. The fact that resistance to gentamicin was almost non-existent in community E. coli is of no help in the treatment of UTI, but means that primary septicaemia originating from UTIs with E. coli can be treated as effectively with gentamicin today as it was 30 years ago.
![]() |
Acknowledgements |
---|
![]() |
Footnotes |
---|
![]() |
References |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
2 . The Microbial Threat. Invitational EU Conference, Copenhagen, Denmark, September 1998 (Workshops 78 September).
3 . Winstanley, T. G., Limb, D. I., Eggington, R. & Hancock, F. (1997). A 10 year survey of the antimicrobial susceptibility of urinary tract isolates in the UK: the Microbe Base project. Journal of Antimicrobial Chemotherapy 40, 5914.[Abstract]
4 . Trienekens, T., Stobberingh, E., Beckers, F. & Knottnerus, A. (1994). The antibiotic susceptibility patterns of uropathogens isolated from general practice patients in southern Netherlands. Journal of Antimicrobial Chemotherapy 33, 10646.[ISI][Medline]
5 . Aguiar, J. M., Chacon, J., Canton, R. & Baquero, F. (1992). The emergence of highly fluoroquinolone-resistant E. coli in community-acquired urinary tract infections. Journal of Antimicrobial Chemotherapy 29, 34950.[ISI][Medline]
6
.
Garau, J., Xercavins, M., Rodriguez-Carballeria, M., Gomex-Vera, J. R., Coll, I., Vidal, D. et al. (1999). Emergence and dissemination of quinolone-resistant E. coli in the community. Antimicrobial Agents and Chemotherapy 43, 273641.
7
.
Kahlmeter, G. (2000). The ECO·SENS Project: a prospective, multinational, multicentre epidemiological survey of the prevalence and antimicrobial susceptibility of urinary tract pathogensinterim report. Journal of Antimicrobial Chemotherapy 46, Suppl. S1, 1522.
8 . Rubin, R. H., Shapiro, E. D., Andriole, V. T., Davis, R. J. & Stamm, W. E. (1992). Evaluation of new anti-infective drugs for the treatment of urinary tract infection. Infectious Disease Society and the Food and Drug Administration. Clinical Infectious Diseases 15, Suppl., S21627.[ISI][Medline]
9 . The Swedish Reference Group for Antibiotics. (1997). Antimicrobial susceptibility testing in Sweden. Scandinavian Journal of Infectious Diseases Supplementum 105, 531, and updates at http://www.srga.org (7 November 2002, date last accessed).[Medline]
10
.
Manges, A. R., Johnson, J. R., Foxman, B., OBryen, T. T., Fullerton, K. E. & Riley, L. W. (2001). Widespread distribution of urinary tract infections caused by a multidrug-resistant E. coli clonal group. New England Journal of Medicine 345, 100713.
11 . Gruneberg, R. N. (1994). Changes in urinary pathogens and their antibiotic sensitivities, 19711992. Journal of Antimicrobial Chemotherapy 33, Suppl. A, 18.[ISI][Medline]
12 . Hedman, P., Ringertz, O., Lindstrom, M. & Olsson, K. (1993). The origin of Staphylococcus saprophyticus from cattle and pigs. Scandinavian Journal of Infectious Diseases 25, 5760.[ISI][Medline]
13 . Kahlmeter, G. (2001). Antimicrobial resistance in Staphylococcus saprophyticus from UTI in Sweden and from UTI in the ECO·SENS Project. Poster 516, ECCMID, Istanbul, April 14, 2001.
14
.
Gupta, K., Scholes, D. & Stamm, W. (1999). Increasing prevalence of antimicrobial resistance among uropathogens causing acute uncomplicated cystitis in women. Journal of the American Medical Association 281, 7368.
15 . Kresken, M., Hafner, D., Mittermayer, H., Verbist, L., Bergogne-Berezin, E., Giamorellou, H. et al. (1994). Prevalence of fluoroquinolone resistance in Europe. Study Group Bacterial Resistance of the Paul Ehrlich Society for Chemotherapy. Infection 22, Suppl. 2, S908.[ISI][Medline]
16
.
Magee, J. T., Pritchard, E. L., Fitzgerald, K. A., Dunstan, F. D. J. & Howard, A. J. (1999). Antibiotic prescribing and antibiotic resistance in community practice; retrospective study, 19968. British Medical Journal 319, 123940.
17 . Goldstein, F.W. & the Multicentre Study Group. (2000). Antibiotic susceptibility of bacterial strains isolated from patients with community-acquired urinary tract infections in France. European Journal of Clinical Microbiology and Infectious Diseases 19, 1127.[CrossRef][ISI][Medline]
18
.
Howard, A. J., Magee, J. T., Fitzgerald, K. A. & Dunstan, F. D. (2001). Factors associated with antibiotic resistance in coliform organisms from community urinary tract infections in Wales. Journal of Antimicrobial Chemotherapy 47, 30513.
19 . Warren, J. W., Abrutyn, E., Hebel, J. R., Johnson, J. R., Schaeffer, A. J. & Stamm, W. E. (1999). Guidelines for antimicrobial treatment of uncomplicated acute bacterial cystitis and acute pyelonephritis in women. Clinical Infectious Diseases 29, 74558.[ISI][Medline]
20
.
Goettsch, W., van Pelt, W., Nagelkerke, N., Hendrix, M. G. R., Buiting, A. G. M., Petit, P. L. et al. (2000). Increasing resistance to fluoroquinolones in E. coli from urinary tract infections in The Netherlands. Journal of Antimicrobial Chemotherapy 46, 2238.
21
.
Piddock, L. J. V. (1998). Fluoroquinolone resistance. British Medical Journal 317, 102930.