Comparative Evaluation of Fosfomycin Activity with other Antimicrobial Agents against E.coli Isolates from Urinary Tract Infections

Abstract

Introduction: Fosfomycin is a broad spectrum anti-microbial agent with activity against various bacterial agents. It is a bactericidal antibiotic which interferes with cell wall synthesis. Fosfomycin is rapidly absorbed orally and majority of the drug is excreted unchanged in urine with very high concentration levels achieved in urine after a single oral dose. Urine levels remain high for prolonged period which makes it a suitable drug in the treatment of Urinary Tract Infections (UTI). E.coli is the most common organism causing the UTI. With the inappropriate and inadvertent use of higher antibiotics, these bacterial isolates have acquired multidrug resistance for which treatment options are limited. Aim: To evaluate the in-vitro activity of fosfomycin against uropathogenic E.coli and to compare its activity with the other anti-microbial agents. Materials and Methods: This study was a prospective study done in the Department of Microbiology SVS Medical College, Mahbubnagar from Jan 2016 to Mar 2016. A total of 564 urine samples from suspected UTI cases were processed during the Fosfomycin has a renal elimination of 95% and no tubular secretion occurs [4]. It has a relatively long elimination half-life, which varies between 4 and 8 hour [4]. Urine levels remain high for prolonged period which makes it a suitable drug in the treatment of UTI. Fosfomycin has good distribution into tissues, achieving clinically relevant concentrations in serum, kidneys, bladder wall, prostate, lungs, inflamed tissues, and other body fluids [3-6]. UTIs are the most common infections in any healthcare set-up with E.coli being the most common organism causing the infection [2]. With the inappropriate and inadvertent use of higher antibiotics, these bacterial isolates have acquired multidrug resistance and it has become much tougher than ever to treat these infections. As the antibiotic pipeline is empty with only few alternatives available for treating these resistant infections, old antibiotics like fosfomycin, nitrofurantoin, colistin have gained importance recently [7,8]. In the present study we have evaluated the fosfomycin activity against E.coli isolates from urine and compared with various other antimicrobial agents used for the treatment of UTIs. Materials and Methods This was a prospective study done in the Department of Microbiology SVS Medical College, Mahbubnagar from Jan 2016 to Mar 2016. The study was approved and ethical clearance was obtained by the Institutional Ethics Committee. A total of 564 urine samples study period out of which 170 E.coli were isolated. Identification of the organisms were done by routine biochemical testing and antibiotic sensitivity testing was done by Kirby-Bauer disc diffusion testing according to the CLSI guidelines (M100-S23). Results: A total of 170 E.coli isolates were tested for antibiotic susceptibility. Out of 170 isolates 60 (35.30%) were isolated from males and 110 (64.70%) from females with male to female ratio of 1:1.83. Majority of the isolates were obtained from the age group of 21-30 years (25.8%). Antibiotics like fosfomycin, imipenem and methenamine mandelate showed the highest sensitivity with all the isolates (100%) being susceptible to these drugs. Whereas, least sensitivity was observed for amoxyclav (15.2%) followed by cefixime (16.4%) and norfloxacin (21%). Fosfomycin has shown very good in-vitro activity against all the tested isolates when compared with many other antibiotics. Conclusion: In view of emergence of multidrug resistant pathogens, testing for old and forgotten antibiotics like fosfomycin is gaining importance. Because of its unique mechanism of action and low incidence of resistance it can be a potential therapeutic alternative in the treatment of UTI.

Keywords

• antibiotics
• drug resistance
• methenamine
• oral formulation