a Department of Microbiological Research & Development; b Department of Clinical Microbiology, Statens Serum Institut, 5 Artillerivej, 2300 Copenhagen S, Denmark
Sir,
There is considerable concern about the increasing levels of antimicrobial resistance. Results from a recent UK survey showed that, for enterobacteria, the major urinary tract pathogens, ampicillin resistance is now around 40% and resistance to trimethoprim approaches 30%.1 Whereas the development of totally new antimicrobial agents takes several years, the re-evaluation of older antibiotics, which are not widely used, can be conducted more rapidly. As part of two studies of uncomplicated urinary tract infections (UTI) in women we investigated the susceptibility pattern of all the Escherichia coli isolates to mecillinam. A total of 574 isolates from six centres in five countries (UK (two), Sweden, France, Portugal and Greece) were tested against the following antibiotics: ampicillin, amoxycillin/ clavulanic acid, mecillinam, sulphonamides, trimethoprim, sulphamethoxazole/trimethoprim (not by UK centre II), nitrofurantoin and ciprofloxacin. The in vitro susceptibility was determined primarily by agar diffusion using Rosco Neosensitabs (Rosco, Taastrup, Denmark) on Danish Blood Agar (Statens Serum Institut (SSI), Copenhagen, Denmark). Because this medium tends to give false resistant results for mecillinam, such resistant isolates were retested on Isosensitest agar using 25 µg discs (Oxoid, Basingstoke, UK) and/or Etest (AB Biodisk, Solna, Sweden). The susceptibility was determined using the guidelines from Rosco2 and the guidelines issued by the Swedish Reference Group for Antibiotics (SRGA). The percentage of resistance to the eight antibiotics is shown in the Table.
Pivmecillinam, the orally administered form of mecillinam, is an effective treatment for UTI3,4 including bacteriuria during pregnancy.5,6 The observation that a high percentage of E. coli remain susceptible to mecillinam suggests that this antibiotic may have a valuable role in the treatment of uncomplicated UTI in primary care.
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The susceptibility testing was supported by Leo Pharmaceutical Products, Denmark.
Notes
J Antimicrob Chemother 2000; 45: 920921
* Tel: +45-32-68-36-47; Fax: +45-32-68-38-73; E-mail: nfm{at}ssi.dk
References
1 . 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]
2 . Rosco. (1998). Users Guide Neo-Sensitabs, Susceptibility Testing, 10th edn. Rosco, Taastrup, Denmark.
3 . Donald, J. F. & Rimmer, D. M. (1980). An open evaluation of a 3-day course of pivmecillinam, in women (ten 200 mg tablets), with acute uncomplicated cystitis. Journal of International Medical Research 8, 11217.[ISI][Medline]
4 . Gordin, A., Kalima, S., Makela, P. & Antikainen, R. (1987). Comparison of three- and ten- day regimens, with a sulfadiazine trimethoprim combination and pivmecillinam in acute lower urinary tract infections. Scandinavian Journal of Infectious Disease 19, 97102.[ISI][Medline]
5 . Bint, A., Bullock, D., Reeves, D. & Wilkinson, P. (1979). A comparative trial of pivmecillinam and ampicillin in bacteriuria of pregnancy. Infection 7, 2903.[ISI][Medline]
6 . Sanderson, P. & Menday, P. (1984). Pivmecillinam for bacteriuria in pregnancy. Journal of Antimicrobial Chemotherapy 13, 3838.[Abstract]