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In vitro activity of cefpirome against selected clinical enterobacterial isolates with beta-lactamase-mediated
L S Tzouvelekis1, E Tzelepi, A F Mentis
1Dept. of Bacteriology, Hellenic Pasteur Institute, Athens, Greece.
Abstract:
Previous studies have shown that there is a high incidence of resistance to cephalosporins among enterobacteria isolated in Greek hospitals. This resistance is mainly due to either the derepression of chromosomal cephalosporinases or the acquisition of plasmids coding for SHV-5 type beta-lactamase. In the present study the activity of cefpirome against a number of enterobacteria (Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Enterobacter aerogenes and Serratia marcescens) possessing the mechanisms mentioned above was examined. Cefpirome was found active against all the strains characterized by stable derepression of chromosomal class-C enzymes. The antibiotic was less potent against strains expressing SHV-5 type beta-lactamase due to its hydrolysis by the enzyme. Also cefpirome exhibited good activity against E. aerogenes strains with reduced susceptibility to imipenem. These in vitro data suggest that cefpirome might be useful in treating infections caused by these resistant microorganisms that are frequently encountered in Greek hospitals.
Insights
Cefpirome shows activity against resistant enterobacteria in Greek hospitals, particularly those with derepressed chromosomal enzymes. However, its effectiveness is reduced against strains producing SHV-5 beta-lactamase.
Area of Science:
- Microbiology
- Infectious Diseases
- Pharmacology
Background:
- High incidence of cephalosporin resistance in enterobacteria from Greek hospitals.
- Resistance mechanisms include derepressed chromosomal cephalosporinases and SHV-5 beta-lactamase acquisition.
Purpose of the Study:
- To evaluate the in vitro activity of cefpirome against resistant enterobacteria.
- To assess cefpirome's efficacy against specific resistance mechanisms prevalent in Greek hospitals.
Main Methods:
- Testing cefpirome activity against clinical isolates of Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Enterobacter aerogenes, and Serratia marcescens.
- Characterizing strains based on resistance mechanisms: derepressed chromosomal class-C enzymes and SHV-5 beta-lactamase production.
Main Results:
- Cefpirome demonstrated activity against enterobacteria with derepressed chromosomal class-C enzymes.
- Reduced potency of cefpirome was observed against strains expressing SHV-5 beta-lactamase due to hydrolysis.
- Cefpirome showed good activity against Enterobacter aerogenes strains with reduced susceptibility to imipenem.
Conclusions:
- Cefpirome is active against enterobacteria possessing derepressed chromosomal class-C enzymes.
- SHV-5 beta-lactamase significantly reduces cefpirome's in vitro activity.
- Cefpirome may be a valuable therapeutic option for infections caused by these resistant enterobacteria in Greek hospitals.