Antimicrobial susceptibility of multidrug-resistant Gram negative bacteria to fosfomycin.
We evaluated the antimicrobial activity of fosfomycin against a randomly selected sample of 30 Klebsiella pneumoniae, 30 Pseudomonas aeruginosa, and 30 Acinetobacter baumannii multidrug-resistant, clinical isolates from patients in a general tertiary care hospital in Athens, Greece. Standard laboratory methods were used for susceptibility testing to commonly used antibiotics and the detection of extended-spectrum-beta-lactamase (ESBL) and metallo-beta-lactamase (MBL) production. The minimum inhibitory concentration (MIC) of fosfomycin for each isolate was determined by the agar dilution method. All K. pneumoniae isolates were both ESBL and MBL producers; all P. aeruginosa isolates were ESBL producers. The K. pneumoniae strains had fosfomycin MICs distributed across a range of 8-64 microg/ml; MIC(50) was 16 microg/ml and MIC(90) 32 microg/ml. The fosfomycin MICs of the P. aeruginosa strains had a distribution across a range of 4 to over 512 microg/ml; MIC(50) was 32 microg/ml and MIC(90) 128 microg/ml. The fosfomycin MICs of the A. baumannii strains had a distribution across a range of 64 to over 512 microg/ml; MIC(50) was 256 microg/ml and MIC(90) more than 512 microg/ml. Although standardized fosfomycin MIC interpretative breakpoints for the species studied are lacking, the findings of our study support the idea that fosfomycin may be further investigated as one among a decreasing list of therapeutic options for the treatment of infections due to multidrug-resistant strains of, primarily, K. pneumoniae and, secondly, P. aeruginosa.
Falagas
M E
ME
Alfa Institute of Biomedical Sciences, 9 Neapoleos Street, 151 23 Marousi, Athens, Greece. m.falagas@aibs.gr
Kanellopoulou
M D
MD
Karageorgopoulos
D E
DE
Dimopoulos
G
G
Rafailidis
P I
PI
Skarmoutsou
N D
ND
Papafrangas
E A
EA
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D024901:Drug Resistance, Multiple, Bacterial; D005578:Fosfomycin / Q000494:pharmacology*; D006090:Gram-Negative Bacteria / Q000187:drug effects* / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests; D018440:beta-Lactam Resistance / Q000235:genetics; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism*
D000900:Anti-Bacterial Agents; D005578:Fosfomycin; D001618:beta-Lactamases