ABSTRACT. Inhibition of Pseudomonas cepacia (but not Pseudomonas aeruginosa) by &lactams was decreased in 5% C 0 2 in air compared with air alone. The effect of C 0 2 and p H (range, 6.0 to 8.0) on 8-lactam susceptibility, 8-lactamase expression, and outer membrane proteins was studied in isolates recovered from the sputum of children with cystic fibrosis. Incubation in 5% COz decreased the activity of piperacillin, piperacillin/tazobactam, and ceftazidime, although isolates were still clinically sensitive (minimum inhibitory concentrations < 16 mg/L). Cefpirome activity was markedly decreased from a minimum inhibitory concentration of 2.0 to greater than 64 mg/L. On highly buffered 3-(N-morpho1ino)-propane sulfonic acid media, b-lactam susceptibility was eliminated at pH greater 7.5. A 2-to 13-fold increase in @-lactamase activity was demonstrated after growth in 5% C 0 2 compared with basal aerobic levels for 13 of 15 clinical isolates. 8-Lactamase activity did not vary significantly with pH. Addition of imipenem to media (2.0 mg/L) resulted in hyperproduction of 8-lactamase (180-fold). Isoelectric points varied with cultural conditions, and all 8-lactamases detected were inhibited by clavulanate and tazobactam. Significant hydrolysis of piperacillin and ceftazidime could not be demonstrated. A 36-kD porin was present a t all pII tested. Thus, our strains of Pseudomonas cepacia were markedly affected by cultural conditions not normally used in standardized susceptibility tests. However, such conditions may be encountered in the pathologically altered infected lung in cystic fibrosis. (Pediatr Res 35: [299][300][301][302] 1994) Abbreviations O M P , outer membrane protein MIC, minimum inhibitory concentration MOPS, 3-(N-morpholino)-propane sulfonic acid HBMM, highly buffered M O P S media IS0, concentration of inhibitor required to inhibit enzymatic activity by 50% under defined assay conditionsPselidomonas cepacia has emerged as an important opportunist pathogen in pulmonary infections in children with cystic fibrosis (1-3) and its appearance is associated with increased morbidity and mortality (2). Many strains of P. ccpacia are
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2025 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.