Antibiotic susceptibility of bacterial strains isolated from urinary tract infections in Poland

Katarzyna Hryniewicza, Katarzyna Szczypab,*, Agnieszka Sulikowskab, Krzysztof Jankowskia, Katarzyna Betlejewskab and Waleria Hryniewiczb

a Department of Internal Medicine, Warsaw University Medical School, Lindleya 1,Warsaw; b The National Reference Centre for Antibiotics, Sera and Vaccines Central Research Laboratory, Chelmska 30/34, 00-725 Warsaw, Poland


    Abstract
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
Worldwide data show that there is increasing resistance among urinary tract pathogens to conventional drugs. The aim of this study was to obtain data on susceptibility patterns of pathogens responsible for urinary tract infections (UTIs) in Poland to currently used antimicrobial agents. A multicentre study of 141 pathogens from hospital-acquired infections and 460 pathogens from community-acquired infections was carried out between July 1998 and May 1999. The most prevalent aetiological agent was Escherichia coli (73.0%), followed by Proteus spp. (8.9%) and other species of Enterobacteriaceae (9.6%). Few community infections were caused by Gram-positive bacteria (2.2%). Gram-positive cocci were isolated more frequently from a hospital setting (14.1%) and the most common were Enterococcus spp. (8.5%). Pseudomonas aeruginosa was found only among hospital isolates and was responsible for 10.7% of infections. E. coli isolates from both community and hospital infections were highly susceptible to many antimicrobial agents with the exception of those isolates producing extended-spectrum ß-lactamases (ESBLs). Of all Enterobacteriaceae tested, 38 strains (6.9%) were capable of producing ESBLs.


    Introduction
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
Urinary tract infections (UTIs) are one of the most common bacterial infections in humans both in the community and hospital setting.13 In almost all cases there is a need to start treatment before the final microbiological results are available. Area-specific monitoring studies aimed to gain knowledge about the type of pathogens responsible for UTIs and their resistance patterns may help the clinician to choose the right empirical treatment. Many different antimicrobial agents are available in Poland, always on physician prescription, for the treatment of UTI. Co-trimoxazole, trimethoprim, ciprofloxacin, norfloxacin, nitrofurantoin, first and second-generation cephalosporins and semi- synthetic penicillins with or without inhibitors and fosfomycin trometamol are the most commonly used antibacterial drugs in the treatment of UTI outside of the hospital.

The aim of this study was to obtain data on susceptibility patterns of major pathogens from both community and hospital UTIs in Poland to antimicrobial agents currently used in the treatment of UTI.


    Materials and methods
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
Bacterial isolates

Twenty centres participated in the study. They were selected to cover all administrative regions in Poland. The bacterial strains were isolated from urine specimens from 601 patients (25–35 per centre) who either consulted general practitioners (n = 460) in different regions or were hospitalized (n = 141) in University Clinics in Warsaw, Cracow, Wroclaw, Szczecin and Bialystok with symptoms suggestive of UTI. The study was carried out between July 1998 and May 1999. Only patients who had pyuria and significant bacteriuria2 obtained from a clean-catch midstream urine sample were included in the microbiological analysis. Only one specimen per patient was accepted. No mixed infections were encountered. Local laboratories performed identification to species level and antibiotic susceptibility testing by disc diffusion. Subsequently all strains were sent to the National Reference Centre for Antibiotics in the Sera and Vaccines Central Research Laboratory (co-ordinating centre) along with completed questionnaires containing demographic, clinical and microbiological data. They were re-identified to the species level by ID32E, ID32GN, ID32STAPH or rapid ID32STREP (bioMérieux, Charbonnieres-les-Bains, France).

Antimicrobial agents

The antibiotics tested were ampicillin, gentamicin (Polfa, Tarchomin, Poland), co-amoxiclav (SmithKline Beecham, Worthing, West Sussex, UK), piperacillin (Lederle, Piperacillin Inc., Carolina, Puerto Rico), tazobactam (Lederle Laboratories, Pearl River, NY, USA), ceftazidime (Glaxo Wellcome, Stevenage, UK), ceftriaxone, trimethoprim/ sulphamethoxazole (Roche, Basel, Switzerland), trimethoprim (Sigma Chemical Co., St Louis, MO, USA), cephalexin (Polfa), meropenem (Zeneca, Macclesfield, UK), amikacin, cefepime, aztreonam (Bristol-Myers Squibb, New Brunswick, NJ, USA), doxycycline (Pfizer, Groton, CT, USA), netilmicin (Abbott Laboratories, Chicago, IL, USA), norfloxacin (Krka d.d., Nove Mesto, Slovenia), ciprofloxacin (Bayer, Wuppertal, Germany), nitrofurantoin (Unitex/Fis Fabrica Italiana Sintetici SpA, Milano, Italy), fosfomycin trometamol (Zambon Group S.p.A., Lonigo, Italy). For community isolates recovered from uncomplicated infections, 18 antimicrobial agents were tested. For complicated community and all hospital cases, cefepime was also included. For hospital isolates fosfomycin trometamol and cephalexin were excluded since they are used by GPs only.

Antibiotic susceptibility testing

The MICs of antibiotics were determined by the agar dilution method, as described in the National Committee for Clinical Laboratory Standards (NCCLS) guidelines, on Mueller–Hinton agar (bioMérieux).4 An inoculum of 104 cfu/spot was applied to antibiotic-containing plates with a multipoint inoculator (West Sussex Instruments Ltd, Denley, UK). Amoxycillin was combined with clavulanic acid in a 2:1 ratio and the concentration of tazobactam in combinations with piperacillin was 4 mg/L. The conventional double-disc test with co-amoxiclav, ceftriaxone and ceftazidime was used to detect extended-spectrum ß-lactamase (ESBL) production in Enterobacteriaceae strains.5 MICs of aztreonam were determined only for ESBLproducing strains. High-level resistance to gentamicin and streptomycin (Polfa) of all Enterococcus strains was determined on brain–heart infusion agar (Becton Dickinson Microbiology Systems, Cockeysville, MD, USA) supplemented with streptomycin (2000 mg/L) and gentamicin (500 mg/L). Methicillin resistance in staphylococci was detected using an oxacillin 1 µg disc (Becton Dickinson Microbiology Systems).4 For the quality control of susceptibility tests Escherichia coli ATCC 25922, E. coli ATCC 35218, Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 29212, E. faecalis ATCC 51299 and Pseudomonas aeruginosa ATCC 27853 strains were used.

Statistical method

P value was measured by the {chi}2 test with Yates' correction.


    Results
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
The overall species distribution is shown in Table IGo. More than 90% of isolates belonged to the Enterobacteriaceae. The most frequently isolated species from community UTI was E. coli (83.7%) followed by Proteus spp. (9.1%).


View this table:
[in this window]
[in a new window]
 
Table I.  Species distribution of UTI isolates
 
E. coli was also the most common hospital isolate, although responsible for only 38.3% of infections. Among the 460 community isolates, 83 were obtained from patients with complicated infections (e.g. neurogenic bladder, urinary stones, reflux, urethral stricture).6 Results of the in vitro susceptibility testing to antimicrobial agents of UTI isolates from the community and hospital are shown in Tables II–IV GoGoGo. In general E. coli was susceptible to many drugs; however, a high percentage of multi-resistant strains was found amongst other Enterobacteriaceae. Of all Enterobacteriaceae tested, 38 strains were capable of producing ESBLs as shown by double-disc test and MICs of ceftriaxone, ceftazidime and aztreonam. Sixteen of these strains were recovered from complicated community and 22 from hospital UTIs. The distribution of ESBL-positive species was as follows: E. coli (15 strains), Klebsiella spp. (nine strains), Proteus spp. (three strains) and other Enterobacteriaceae (11 strains). Most of the ESBL-positive strains (>80%) were susceptible to piperacillin/tazobactam and only 55.3% to cefepime. All of them were susceptible to meropenem.


View this table:
[in this window]
[in a new window]
 
Table II.  Susceptibility of bacteria isolated from uncomplicated community-acquired UTIs to various antimicrobial agents
 

View this table:
[in this window]
[in a new window]
 
Table III.  Susceptibility of bacteria isolated from complicated community-acquired UTIs to various antimicrobial agents
 

View this table:
[in this window]
[in a new window]
 
Table IV. Susceptibility of Gram-negative bacteria isolated from hospital-acquired UTIs to various antimicrobial agents

 
A very low incidence of community infections caused by Gram-positive bacteria was observed (2.2%). Gram-positive cocci were isolated more frequently from the hospital setting (14.1%) and the most common were Enterococcus spp. (8.5%). Three strains of E. faecalis from hospital expressed high-level resistance to aminoglycosides (HLAR) but all E. faecalis, both from community and hospital, were fully susceptible to ampicillin. Five of the 12 staphylococcal strains isolated were resistant to methicillin.


    Discussion
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
This paper describes the first multicentre study undertaken to evaluate susceptibility patterns of bacterial strains isolated from UTIs in Poland. It provides valuable laboratory data concerning both community and hospital pathogens and enables the situation in Poland to be compared with that in other countries.

Our studies indicate that E. coli is still the most common cause of community-acquired UTI in Poland. This corresponds with the data obtained by other investigators.1,79 Some have shown, however, that the percentage of E. coli is slowly declining, being replaced by other members of the Enterobacteriaceae and enterococci.10 Our patients with complicated community UTI had fewer E. coli and more Proteus spp. The low percentage of E. coli amongst hospital isolates in our study corresponded to that obtained by other investigators.1114 In general, as in other studies, more of our hospital isolates were resistant to antibiotics than were the pathogens causing UTI in the community.10,15

Most E. coli from community infections investigated in this study were susceptible to oral drugs commonly used in general practice such as trimethoprim/sulphamethoxazole, norfloxacin, ciprofloxacin, nitrofurantoin, cephalexin and fosfomycin trometamol. The resistance pattern of hospital E. coli was similar to that of community isolates except for those found to produce ESBL. These data are similar to those obtained in other countries indicating that E. coli is still susceptible to many antimicrobial agents.12,13,16 Other species of the Enterobacteriaceae were more resistant when isolated from the hospital setting.13,17 Multi-resistance was usually related to production of ESBL, in both community and hospital isolates. ESBL producers, however, were recovered only from complicated community UTIs. The percentage of ESBL production by Polish isolates of Enterobacteriaceae was 6.9% and was high as compared with other recently published data.16,18,19 It reflects the overall epidemiological situation in Poland with respect to ESBL production20 and several hospital outbreaks have been described.21 Isolates of P. aeruginosa, in our study found exclusively in nosocomial infections, presented a worrying pattern of resistance. Only meropenem had good activity. A high percentage of ciprofloxacin-resistant strains (53.3%) was found as compared with recent publications on nosocomial isolates recovered from various clinical specimens.11,16,2123 Surprisingly, the new fourth-generation cephalosporin, cefepime, which has just been introduced into the Polish market, exhibited poorer activity toward P. aeruginosa than ceftazidime and piperacillin. The data are different from those reported by Blondeau et al.24 As can be seen from our data, cefepime was inactive (in vitro) against 44.7% of ESBL-producing Enterobacteriaceae. Similar results have been obtained by other workers.25,26

Data presented in this study indicate that antibiotics commonly used in UTIs are still effective, particularly in community infections, but species distribution and their susceptibility to antibiotics are changing in general all around the world. It requires regular monitoring in order to make reliable information available for optimal empirical therapy for patients with UTIs.


    Acknowledgments
 
We thank J. Mahorowski and S. Murchan for critical reading of the manuscript. The authors would like to thank all participating centres. This work was partly supported by the Polish Ministry of Health (DOT 3.2.2000). Part of this work was presented as a poster at the Tenth European Congress of Clinical Microbiology and Infectious Diseases (Abstract WeP168, p. 100).


    Notes
 
* Corresponding author. Tel: +48-22-841-33-67; Fax: +48-22-841-29-49; E-mail: kazbunda{at}urania.il.waw.pl Back


    References
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
1 .  Tice, A. D. (1999). Short course therapy of acute cystitis: a brief review of therapeutic strategies. Journal of Antimicrobial Chemotherapy 43, 85–93.[ISI][Medline]

2 .  Clarridge, J. E., Johnson, J. R. & Pezzlo, M. T. (1998). Cumitech 2B, Laboratory Diagnosis of Urinary Tract Infections, (Weissfeld, A. S., Ed.). American Society for Microbiology, Washington, DC.

3 .  Sussman, M. (1998). Urinary tract infections. In Topley & Wilson's Microbiology and Microbial Infections, 9th edn, (Collier, L., Balows, A. & Sussman, M., Eds), pp. 601–21. Arnold, London.

4 .  National Committee for Clinical Laboratory Standards. (2000). Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria that Grow Aerobically—Fifth Edition: Approved Standard M7-A2. NCCLS, Villanova, PA.

5 .  Jarlier, V., Nicolas, M. H., Fournier, G. & Philippon, A. (1988). Extended broad-spectrum ß-lactamases conferring transferable resistance to newer ß-lactam agents in Enterobacteriaceae: hospital prevalence and susceptibility patterns. Reviews of Infectious Diseases 10, 867–78.[ISI][Medline]

6 .  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 Diseases Society of America and the Food and Drug Administration. Clinical Infectious Diseases 15, Suppl. 1, S216–27.[ISI][Medline]

7 .  Ferry, S., Burman, L. G. & Holm, S. E. (1988). Clinical and bacteriological effects of therapy of urinary tract infection in primary health care: relation to in vitro sensitivity testing. Scandinavian Journal of Infectious Diseases 20, 535–44.[ISI][Medline]

8 .  Stamm, W. E. & Hooton, T. M. (1993). Management of urinary tract infections in adults. New England Journal of Medicine 329, 1328–34.[Free Full Text]

9 .  Henry, D., Ellison, W., Sullivan, J., Mansfield, D. L., Magner, D. J., Dorr, M. B. et al. (1998). Treatment of community acquired acute uncomplicated urinary tract infection with sparfloxacin versus ofloxacin. The Sparfloxacin Multi-Center UUTI Study Group. Antimicrobial Agents and Chemotherapy 42, 2262–6.[Abstract/Free Full Text]

10 . Gruneberg, R. N. (1994). Changes in urinary pathogens and their antibiotic sensitivities 1971–1992. Journal of Antimicrobial Chemotherapy 33, Suppl. A, 1–8.[ISI][Medline]

11 . Thomson, K. S., Sanders W. E. & Sanders C. C. (1994). USA resistance patterns among UTI pathogens. Journal of Antimicrobial Chemotherapy 33, Suppl. A, 9–15.[ISI][Medline]

12 . Fluit, A. C., Jones, M. E., Schmitz, F. J., Acar, J., Gupta, R. & Verhoef, J. (2000). Antimicrobial resistance among urinary tract infection (UTI) isolates in Europe: results from the SENTRY Antimicrobial Surveillance Program 1997. Antonie van Leeuwenhoek 77, 147–52.[ISI][Medline]

13 . Cunney, R. J., McNally, R. M., McNamara, E. M., Al-Ansari, N. & Smyth, E. G. (1992). Susceptibility of urinary pathogens in a Dublin teaching hospital. Irish Journal of Medical Science 161, 623–5.[ISI][Medline]

14 . Weber, G., Riesenberg, K., Schlaeffer, F., Peled, N., Borer, A. & Yagupsky, P. (1997). Changing trends in frequency and antimicrobial resistance of urinary pathogens in outpatient clinics and a hospital in Southern Israel, 1991–1995. European Journal of Clinical Microbiology and Infectious Diseases 16, 834–8.[ISI][Medline]

15 . Garcia-Rodriguez, J. A., Trujillano Martin I., Baquero, E., Cisterna, R., Gobernado, M., Linares, F. et al. (1997). In vitro activity of fosfomycin trometamol against pathogens from urinary tract infections: a Spanish multicenter study. Journal of Chemotherapy 9, 394–402.[ISI][Medline]

16 . Jones, R. N., Kugler, K. C., Pfaller, M. A., Winokur, P. L. & The SENTRY Surveillance Group, North America. (1999). Characteristics of pathogens causing urinary tract infections in hospitals in North America: Results from the SENTRY Antimicrobial Surveillance Program, 1997. Diagnostic Microbiology and Infectious Disease 35, 55–63.[ISI][Medline]

17 . Vromen, M., van der Ven, A. J., Knols, A. M. & Stobberingh, E. E. (1999). Antimicrobial resistance patterns in urinary tract isolates from nursing home residents. Fifteen years of data reviewed. Journal of Antimicrobial Chemotherapy 44, 113–6.[Abstract/Free Full Text]

18 . Cormican, M., Morris, D., Corbett-Feeney, G. & Flynn, J. (1998). Extended spectrum beta-lactamase production and fluoroquinolone resistance in pathogens associated with community acquired urinary tract infection. Diagnostic Microbiology and Infectious Disease 32, 317–9.[ISI][Medline]

19 . Gales, A. C., Jones, R. N., Gordon, A., Sader, H. S., Wilke, W. W., Beach, M. L. et al. (2000). Activity and spectrum of 22 antimicrobial agents tested against urinary tract infection pathogens in hospitalized patients in Latin America: report from the second year of the SENTRY Antimicrobial Surveillance Program (1998). Journal of Antimicrobial Chemotherapy 45, 295–303.[Abstract/Free Full Text]

20 . Hryniewicz, W., Trzcinski, K., Nowak, J. & Giffing, I. (1996). National survey of the susceptibility of clinically important bacterial pathogens isolated in Poland in 1995 to piperacillin/tazobactam and other antimicrobial agents. In Program and Abstracts of the Eighth International Congress of Bacteriology and Applied Microbiology Division, Jerusalem, Israel, 1996. p. 165. International Union of Microbiological Societies.

21 . Palucha, A., Mikiewicz, B., Hryniewicz, W. & Gniadkowski, M. (1999). Concurrent outbreaks of extended-spectrum ß-lactamase-producing organisms of the family Enterobacteriaceae in a Warsaw hospital. Journal of Antimicrobial Chemotherapy 44, 489–99.[Abstract/Free Full Text]

22 . Gniadkowski, M., Skoczynska, A., Fiett, J., Trzcinski, K. & Hryniewicz, W. (1998). Susceptibility of Pseudomonas aeruginosa isolated from hospital infections to antibiotics. Polski Merkuriusz Lekarski 5, 346–50.[Medline]

23 . Amyes, S. G., Baird, D. R., Crook, D. W. Gillespie, S. H., Howard, A. J., Oppenhiem, B. A. et al. (1994). A multicentre study of the in-vitro activity of cefotaxime, cefuroxime, ceftazidime, ofloxacin and ciprofloxacin against blood and urinary pathogens. Journal of Antimicrobial Chemotherapy 34, 639–48.[Abstract]

24 . Blondeau, J. M., Laskowski, R., Borsos, S. & The Canadian Afermenter Study Group. (1999). In-vitro activity of cefepime and seven other antimicrobial agents against 1518 non-fermentative Gram-negative bacilli collected from 48 Canadian health care facilities. Journal of Antimicrobial Chemotherapy 44, 545–8.[Abstract/Free Full Text]

25 . Aksaray, S., Dokuzoguz, B., Güvener, E., Yücesoy, M., Yulug, N., Kocagöz, S. et al. (2000). Surveillance of antimicrobial resistance among Gram-negative isolates from intensive care units in eight hospitals in Turkey. Journal of Antimicrobial Chemotherapy 45, 695–9.[Abstract/Free Full Text]

26 . Joshi, M., Brull, R., Sompali, N., Qayumi, S., Johnson, J. A., Caspar, P. et al. (2000). Clinical outcomes of cefepime treatment on infections caused by ESBL- and AmpC-producing Enterobacteriaceae. In Program and Abstracts of the Fortieth Interscience Conference on Antimicrobial Agents and Chemotherapy, Toronto, Canada, 2000. Abstract 1716, p. 426. American Society for Microbiology, Washington, DC.

Received 10 October 2000; returned 29 December 2000; revised 19 February 2001; accepted 13 March 2001