cefoxitin and Cystic-Fibrosis

Mycobacteroides abscessus is an opportunistic pathogen in people with structural lung conditions such as bronchiectasis, chronic obstructive pulmonary disease, and cystic fibrosis. Pulmonary M. abscessus infection causes progressive symptomatic and functional decline as well as diminished lung function and is often incurable with existing antibiotics. We investigated the efficacy of a new tetracycline, omadacycline, in combination with existing antibiotics recommended to treat this indication, in a mouse model of M. abscessus lung disease. Amikacin, azithromycin, bedaquiline, biapenem, cefoxitin, clofazimine, imipenem, linezolid, and rifabutin were selected as companions to omadacycline. M. abscessus burden in the lungs of mice over a 4-week treatment duration was considered the endpoint. Omadacycline in combination with linezolid, imipenem, cefoxitin, biapenem, or rifabutin exhibited early bactericidal activity compared to any single drug. Using three M. abscessus isolates, we also determined the

Topics: Animals; Anti-Bacterial Agents; Cefoxitin; Cystic Fibrosis; Imipenem; Linezolid; Mice; Microbial Sensitivity Tests; Mycobacterium abscessus; Rifabutin; Tetracyclines

The in vitro activity of cefoxitin and imipenem was compared for 43 strains of the Mycobacterium abscessus complex, mostly isolated from cystic fibrosis patients. The MICs of imipenem were lower than those of cefoxitin, although the number of imipenem-resistant strains was higher according to the CLSI breakpoints. Strain comparisons indicated that the MICs of cefoxitin were significantly higher for Mycobacterium bolletii than for M. abscessus. The MICs of both β-lactams were higher for the rough morphotype than for the smooth morphotype. The clinical impact of the in vitro difference between the activity of imipenem and that of cefoxitin remains to be determined.

Topics: Anti-Bacterial Agents; Cefoxitin; Colony Count, Microbial; Cystic Fibrosis; Humans; Imipenem; Microbial Sensitivity Tests; Nontuberculous Mycobacteria; Respiratory Tract Infections

The incidence of pulmonary infections in children with cystic fibrosis caused by Pseudomonas cepacia, an organism which may possess an inducible beta-lactamase, has increased since 1978. Seven of 13 sputum isolates of P. cepacia from children with cystic fibrosis were classified as inducible by quantitative enzyme production following preincubation with 100, 200, or 400 micrograms/ml of cefoxitin. The recovery of inducible strains tended to be associated with recent ceftazidime therapy. Susceptibility to aztreonam, ceftazidime, and piperacillin alone or combined with the beta-lactamase inhibitors. YTR 830 or sulbactam, and isoelectric focusing for beta-lactamase were performed. Inducible isolates produced significantly more beta-lactamase than noninducible strains with or without the addition of cefoxitin. Noninducible isolates were more susceptible than inducible isolates to 8 micrograms/ml of piperacillin, a difference that was eliminated with the addition of either beta-lactamase inhibitor. Twelve of 13 strains produced a beta-lactamase band in the pH range of 7.9-8.1; no differences in satellite patterns were noted between the two groups of organisms. Increased production of beta-lactamase in the absence of an inducer may account for piperacillin resistance in P. cepacia in children with cystic fibrosis.

Topics: Analysis of Variance; Aztreonam; beta-Lactamase Inhibitors; beta-Lactamases; Cefoxitin; Ceftazidime; Child; Cystic Fibrosis; Humans; Isoelectric Focusing; Penicillin Resistance; Piperacillin; Pseudomonas; Sputum