<abstract xmlns="http://www.w3.org/1999/xhtml">

<p>Urinary tract infections are caused mostly by uropathogenic <italic>Escherichia coli</italic> strains. The aim of this paper was to assess the activity of fosfomycin <italic>in vitro</italic> against 74 <italic>E. coli</italic> strains isolated from urine samples of outpatients with acute cystitis. Minimum inhibitory concentration (MIC) was determined by the recommended method of serial drug dilution in Mueller-Hinton agar supplemented with glucose-6-phosphate (25 mg/L). The estimated MIC values were in the range of 1-32 mg/L. The prevalence of fosfomycin-sensitive strains was 45.9%, while that of fosfomycin-resistant strains – 54.1%. The time-kill assay was performed for a chosen clinical strain (MIC = 1 mg/L) in Mueller-Hinton broth also supplemented with glucose-6-phosphate in the presence of various concentrations of fosfomycin (0.5-64 mg/L). The bacterial population density was expressed as log CFU (colony forming units)/mL. The decrease of the bacterial population viability after 6h incubation was found with ∆log CFU/mL = 1.05-5.02, depending on fosfomycin concentration. However, bactericidal effect of this antibiotic (∆log CFU/mL >3) was observed only at the highest concentrations (32-64 mg/L). Moreover, after prolonged incubation (24 h), the re-growth of bacterial population revealed as the increase of its viability (∆log CFU/mL = 1.03-3.03) was observed at fosfomycin concentration in the range 0.5-32 mg/L, but not at 64 mg/L. This phenomenon may be due the presence of subpopulations of spontaneous mutants sensitive only to higher concentrations of this antibiotic comparing to MIC. The presented data confirm a need to monitor the sensitivity of uropathogenic <italic>E. coli</italic> strains to fosfomycin.</p>
</abstract>

Urinary tract infections are caused mostly by uropathogenic Escherichia coli strains. The aim of this paper was to assess the activity of fosfomycin in vitro against 74 E. coli strains isolated from urine samples of outpatients with acute cystitis. Minimum inhibitory concentration (MIC) was determined by the recommended method of serial drug dilution in Mueller-Hinton agar supplemented with glucose-6-phosphate (25 mg/L). The estimated MIC values were in the range of 1-32 mg/L. The prevalence of fosfomycin-sensitive strains was 45.9%, while that of fosfomycin-resistant strains – 54.1%. The time-kill assay was performed for a chosen clinical strain (MIC = 1 mg/L) in Mueller-Hinton broth also supplemented with glucose-6-phosphate in the presence of various concentrations of fosfomycin (0.5-64 mg/L). The bacterial population density was expressed as log CFU (colony forming units)/mL. The decrease of the bacterial population viability after 6h incubation was found with ∆log CFU/mL = 1.05-5.02, depending on fosfomycin concentration. However, bactericidal effect of this antibiotic (∆log CFU/mL >3) was observed only at the highest concentrations (32-64 mg/L). Moreover, after prolonged incubation (24 h), the re-growth of bacterial population revealed as the increase of its viability (∆log CFU/mL = 1.03-3.03) was observed at fosfomycin concentration in the range 0.5-32 mg/L, but not at 64 mg/L. This phenomenon may be due the presence of subpopulations of spontaneous mutants sensitive only to higher concentrations of this antibiotic comparing to MIC. The presented data confirm a need to monitor the sensitivity of uropathogenic E. coli strains to fosfomycin.

Fosfomycin activity <italic>in vitro</italic> against <italic>Escherichia coli</italic> strains isolated from urine specimens

Department of Pharmaceutical Microbiology

Current Issues in Pharmacy and Medical Sciences

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Fosfomycin activity  against  strains isolated from urine specimens

Urinary tract infections are caused mostly by uropathogenic Escherichia coli strains. The aim of this paper was to assess the activity of fosfomycin in vitro...

Fosfomycin activity in vitro against Escherichia coli strains isolated from urine specimens

Published Online: Dec 25, 2023

Page range: 217 - 220

Received: Jun 21, 2023

Accepted: Nov 12, 2023

DOI: https://doi.org/10.2478/cipms-2023-0037

Keywords
urinary tract infections, minimum inhibitory concentration, fosfomycin-resistance, fosfomycin-sensitive strains, re-growth

© 2023 Magdalena Zdzieblo et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Fosfomycin activity in vitro against Escherichia coli strains isolated from urine specimens

Published Online: Dec 25, 2023

Page range: 217 - 220

Received: Jun 21, 2023

Accepted: Nov 12, 2023

DOI: https://doi.org/10.2478/cipms-2023-0037

Keywordsurinary tract infections, minimum inhibitory concentration, fosfomycin-resistance, fosfomycin-sensitive strains, re-growth

© 2023 Magdalena Zdzieblo et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Keywords
urinary tract infections, minimum inhibitory concentration, fosfomycin-resistance, fosfomycin-sensitive strains, re-growth