Change in antimicrobial susceptibility of Escherichia coli urinary tract isolates at a single institution over a period of 10 years

Fosfomycin: A First-Line Oral Therapy for Acute Uncomplicated Cystitis

Fosfomycin is a new agent to Canada approved for the treatment of acute uncomplicated cystitis (AUC) in adult women infected with susceptible isolates of E. coli and Enterococcus faecalis. We reviewed the literature regarding the use of oral fosfomycin for the treatment of AUC. All English-language references from 1975 to October 2015 were reviewed. In Canada, fosfomycin tromethamine is manufactured as Monurol® and is available as a 3-gram single dose sachet. Fosfomycin has a unique chemical structure, inhibiting peptidoglycan synthesis at an earlier site compared to β-lactams with no cross-resistance with other agents. Fosfomycin displays broad-spectrum activity against ESBL-producing, AmpC-producing, carbapenem-non-susceptible, and multidrug-resistant (MDR) E. coli. Resistance to fosfomycin in E. coli is rare (<1%). Fosfomycin is excreted unchanged in the urine by glomerular filtration with peak urinary concentration ~4000 µg/mL and remains at concentrations >100 µg/mL for 48 hours after a single 3-gram oral dose. No dosage adjustments are required in elderly patients, in pregnant patients, or in either renal or hepatic impairment. Fosfomycin demonstrates a favorable safety profile, and clinical trials have demonstrated efficacy in AUC that is comparable to ciprofloxacin, nitrofurantoin, and trimethoprim-sulfamethoxazole. Fosfomycin's in vitro activity against common uropathogens, including MDR isolates, its favorable safety profile including pregnancy patients, drug interactions, and clinical trials data demonstrating efficacy in AUC, has resulted in Canadian, US, and European guidelines/authorities recommending fosfomycin as a first line agent for the treatment of AUC.

Longitudinal surveillance of outpatient tetracycline, sulfonamide-trimethoprim and 'other' antimicrobial use in Canada, 1995 to 2010

INTRODUCTION

Monitoring the volume and patterns of use of antimicrobial agents is important in light of antimicrobial resistance.

OBJECTIVE

To assess the use of three antimicrobial groups - tetracycline, sulfonamide-trimethoprim and 'other' antimicrobials - within Canadian provinces over time.

METHODS

Prescription counts from 1995 to 2010 were acquired for the tetracycline and sulfonamide-trimethoprim groups of antimicrobials, and from 2001 to 2010 for the 'other' antimicrobial group. Linear mixed models were produced to assess differences among provinces and over time while accounting for repeated measurements. Prescription rate, defined daily dose per 1000 inhabitant-days and defined daily doses per prescription measures for the year 2009 were also compared with those reported by participating European Union countries to determine where Canadian provinces rank in terms of antimicrobial use among these countries.

RESULTS

Prescribing of all three groups varied according to province and over time. Tetracycline and sulfonamide-trimethoprim group prescribing were significantly reduced over the study period, by 36% and 61%, respectively. Prescribing of the 'other' antimicrobial group increased in all provinces from 2001 to 2010 with the exception of Prince Edward Island, although by varying amounts (10% to 61% increases).

DISCUSSION

The overall use of antimicrobials in Canada has dropped from 1995 to 2010, and the tetracycline and sulfonamide-trimethoprim groups have contributed to this decline. The use of the 'other' antimicrobials has increased, however. These results may suggest that switches are being made among these groups, particularly among the antimicrobials used to treat urinary tract infections.