title: High-level beta-lactamase activity in sputum samples from cystic fibrosis patients during antipseudomonal treatment.
abstract: The in vivo activity and source of beta-lactamase in sputum samples from 43 patients with cystic fibrosis (CF) during a 2-week antipseudomonal treatment were studied. A colorimetric method, based on the conversion of nitrocefin, was used for quantitation of the sputum beta-lactamase activity. beta-Lactamases in sputum were characterized by isoelectric focusing and inhibition profile and were compared with the beta-lactamases extracted from Pseudomonas aeruginosa isolated from the paired sputum samples. We found that the beta-lactamase activity increased to high levels in sputum from patients with CF during the course of piperacillin, ceftazidime, cefsulodin, or imipenem therapy. Aztreonam therapy lead to opposite results because the beta-lactamase activity decreased and aztreonam was able to mask beta-lactamase activity by acting as an inhibitor. All sputum beta-lactamases displayed characteristics indicative of a class I enzyme, identical to the beta-lactamases extracted from P. aeruginosa. The presence of beta-lactamase at such levels could lead to in vivo inactivation of beta-lactam antibiotics. This study supports the hypothesis that beta-lactamase production is an important in vivo resistance mechanism in P. aeruginosa-infected patients with CF.
authors.affiliation: Institute of Medical Microbiology, University of Copenhagen, Denmark.
authors.forename: B
authors.initials: B
authors.lastname: Giwercman
authors.forename: C
authors.initials: C
authors.lastname: Meyer
authors.forename: P A
authors.initials: PA
authors.lastname: Lambert
authors.forename: C
authors.initials: C
authors.lastname: Reinert
authors.forename: N
authors.initials: N
authors.lastname: Høiby
mesh_terms: D000293:Adolescent; D000328:Adult; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D002648:Child; D003550:Cystic Fibrosis / Q000150:complications / Q000201:enzymology*; D005260:Female; D006801:Humans; D007525:Isoelectric Focusing; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D011552:Pseudomonas Infections / Q000150:complications / Q000188:drug therapy / Q000201:enzymology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000201:enzymology / Q000302:isolation & purification; D013183:Sputum / Q000201:enzymology* / Q000382:microbiology; D001618:beta-Lactamases / Q000378:metabolism*; D047090:beta-Lactams
chemical_list: D000900:Anti-Bacterial Agents; D047090:beta-Lactams; D001618:beta-Lactamases