title: Antimicrobial susceptibility of multidrug-resistant Gram negative bacteria to fosfomycin.
abstract: 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.
authors.affiliation: Alfa Institute of Biomedical Sciences, 9 Neapoleos Street, 151 23 Marousi, Athens, Greece. m.falagas@aibs.gr
authors.forename: M E
authors.initials: ME
authors.lastname: Falagas
authors.forename: M D
authors.initials: MD
authors.lastname: Kanellopoulou
authors.forename: D E
authors.initials: DE
authors.lastname: Karageorgopoulos
authors.forename: G
authors.initials: G
authors.lastname: Dimopoulos
authors.forename: P I
authors.initials: PI
authors.lastname: Rafailidis
authors.forename: N D
authors.initials: ND
authors.lastname: Skarmoutsou
authors.forename: E A
authors.initials: EA
authors.lastname: Papafrangas
mesh_terms: 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*
chemical_list: D000900:Anti-Bacterial Agents; D005578:Fosfomycin; D001618:beta-Lactamases