title: Effect of basic amino acids on susceptibility to carbapenems in clinical Pseudomonas aeruginosa isolates.
abstract: We evaluated effects of medium composition, including basic amino acid content and pH, on susceptibility to carbapenems such as imipenem, panipenem and meropenem, in clinical isolates of Pseudomonas aeruginosa. Susceptibility to carbapenems was reduced by basic amino acids in the medium, while susceptibilities to ceftazidime and aztreonam were not. Among carbapenems, susceptibility to panipenem was most sharply reduced by addition of basic amino acids to 1:16 Mueller-Hinton agar (MHA). In 174 of 175 clinical isolates, MICs for carbapenems were affected to different degrees by medium composition. One isolate, in which MICs for carbapenems did not differ between MHA and 1:16 MHA, showed reduced production of porin (OprD). Our results suggest that susceptibility to individual carbapenems, especially panipenem, is difficult to evaluate based on MICs for other carbapenems determined on MHA. For a better prediction of antibiotic efficacy, it may be important to evaluate the susceptibility for each carbapenem individually.
authors.affiliation: Division of Pharmacy, Hamamatsu University School of Medicine, Hamamatsu, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Muramatsu
authors.forename: Toshinobu
authors.initials: T
authors.lastname: Horii
authors.forename: Motoki
authors.initials: M
authors.lastname: Morita
authors.forename: Hisakuni
authors.initials: H
authors.lastname: Hashimoto
authors.forename: Takashi
authors.initials: T
authors.lastname: Kanno
authors.forename: Masato
authors.initials: M
authors.lastname: Maekawa
mesh_terms: D024361:Amino Acids, Basic; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001398:Aztreonam / Q000494:pharmacology; D015780:Carbapenems / Q000494:pharmacology*; D002442:Ceftazidime / Q000494:pharmacology; D003470:Culture Media; D006801:Humans; D006863:Hydrogen-Ion Concentration; D015378:Imipenem / Q000494:pharmacology; D000077731:Meropenem; D008826:Microbial Sensitivity Tests; D018272:Porins / Q000096:biosynthesis; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D013845:Thienamycins / Q000494:pharmacology
chemical_list: D024361:Amino Acids, Basic; D000900:Anti-Bacterial Agents; D015780:Carbapenems; D003470:Culture Media; D018272:Porins; D013845:Thienamycins; C077157:OprD protein, Pseudomonas aeruginosa; D015378:Imipenem; D002442:Ceftazidime; D000077731:Meropenem; D001398:Aztreonam; C039536:panipenem