Beta Lactam/Beta Lactamase Inhibitor Combination in the Treatment of Urinary Tract Infections Caused by Extended Spectrum Beta Lactamase Producing Escherichia coli
Geeta Shakya M.D., Bishnu Upadhyaya M.Sc., Nisha Rijal M.Sc., Madhu K. Mahato M.Sc., Shailaja Adhikari M.Sc., Palpasa Kansakar Ph.D
ABSTRACT
Background: Extende d Spectrum Beta Lactamase (ESBL) producing strains often le ad to the failure of
empirical therapy, a common proble m in urinary tract infection (UTI). Though combination therapy ofbeta-lactam/beta-lactamase inhibitors (BL+BLI) is an alternative to combat resistance due to ESBL production,co- production of AmpC and other inhibitor resistant beta-lactamases may render them ineffective. Methods: We attempted to search for AmpC co-production and antimicrobial options for 100 uropathogenic
ESBL Escherichia coli by testing in vitro susceptibility towards three clinically used combinations of (BL+BLI)different generations of
fluoroquinolones, imipenem, cefepime, fosfomycin and amikacin.
Results: ESBL producers comprised 45% of uropathogenic E. coli isolated and 26% of these were AmpC co- producers. All ESBL strains were resistant to cefepime. Cefoperazone-sulbactam revea le d only mode rate
activity (44% resistance), while piperacillin-tazobactam (91% resistance) and ticarcillin-clalvulanate (100% resistance) showed poor in vitro activity. No isolates were susceptible to norfloxacin and gatifloxacin, and only 17% were susceptible to levofloxacin. Amikacin, fosfomycin, and imipenem showed good in vitro activity (98-100%susceptible ).
Conclusion: BL+BLI used in the study showed limited in vitro activity against ESBL E. coli. Fosfomycin, a non-traditional oral antibiotic mayserve as an alternative to carbapenems. New BL+BLI combinations that are effective against Class A and C beta-lactamases shou ld be explored. (J Infect Dis Antimicrob Agents
2014;31:69-77.)
Keyword : beta lactam, beta lactamases, Escherichia coli, ESBL, Multi-drug Resistance