Successful treatment with tigecycline of two patients with complicated urinary tract infections caused by extended-spectrum -lactamase-producing Escherichia coli

Sir, We read with great interest the letter by Nix and Matthias1 regarding pharmacokinetic considerations relating to tigecycline use in urinary tract infections (UTIs). We agree with the authors that tigecycline should not be used for UTIs when other therapies including aminoglycosides, carbapenems and colistin are options; however, in rare situations, tigecycline may be considered. In a recent study, Rodríguez-Baño et al.2 demonstrated that the susceptibility of all extended-spectrum β-lactamase (ESBL)-producing Escherichia coli to tigecycline was 100%. Since ESBL-producing E. coli is an increasing cause of community-onset bloodstream infections, they suggested that tigecycline might be an alternative in the treatment of non-UTIs. Here, we describe two patients with complicated UTIs caused by ESBL-producing E. coli, who were successfully treated with tigecycline. The first patient was a 44-year-old renal transplant recipient with end-stage renal disease (ESRD) due to diabetic nephropathy with recurrent renal transplant pyelonephritis with an ESBL E. coli. For the first two UTIs he was treated with meropenem with treatment durations of 2 and 6 weeks, respectively, but within 4 weeks he had a recurrent UTI with systemic symptoms. Urological evaluation did not show any anatomical abnormalities, but because of the recurrent UTIs a chronic prostatitis was suspected. It was decided not to treat him again with a carbapenem, but with tigecycline for 6 weeks, because tetracyclines are lipophilic and reach higher tissue levels in the prostate. The second patient was a 66-year-old female who was on haemodialysis due to ESRD caused by autosomal dominant polycystic kidney disease and who had recurrent UTIs with ESBL E. coli owing to infected renal cysts shown on positron emission tomography CT. Because she had allergies to β-lactam antibiotics and carbapenems, she was treated with tigecycline for 6 weeks. Five (Patient 1) and 4 (Patient 2) months after the end of treatment, both patients had not developed a new UTI. Tigecycline is a tetracycline derivative and has broad antimicrobial activity, fortunately often also against ESBL-producing microorganisms.2,3 Since only 30% of a dose is excreted in urine, it is not licensed for the treatment of UTIs. Furthermore, it is also not licensed for immunocompromised patients. However, with the increase in ESBL-producing microorganisms, sometimes no other treatment possibilities are present. In summary, we report two patients with complicated UTIs caused by ESBL-producing E. coli with possible foci in prostate and renal cysts, respectively, who were successfully treated with tigecycline. We think that with the worldwide increasing ESBL problem, further research with tigecycline for the treatment of UTIs is warranted. This study was carried out as part of our routine work. None to declare.