Beta Lactam Resistance
Mostrando 25-36 de 307 artigos, teses e dissertações.
-
25. Occurrence of a beta-lactam-inducible penicillin-binding protein in methicillin-resistant staphylococci.
The mechanism of methicillin resistance was investigated in methicillin-resistant staphylococci (MRS) and in variants which had lost methicillin resistance. Phase-contrast microscopy showed that cells swelled at low concentrations of beta-lactam antibiotics in both MRS and variants which had lost methicillin resistance. Cells of variants which had lost methi
-
26. Beta-Lactamase Production and Resistance to Beta-Lactam Antibiotics in Nocardia
Although ampicillin has been suggested as a useful agent for the treatment of nocardiosis in man, little is known regarding the presence of beta-lactamase in Nocardia or its possible role in determining resistance to ampicillin and the other beta-lactam antibiotics. We have evaluated 55 isolates of Nocardia for susceptibility to five beta-lactam antibiotics
-
27. Beta-lactamase of Mycobacterium fortuitum: kinetics of production and relationship with resistance to beta-lactam antibiotics.
The kinetics of both intracellular and extracellular beta-lactamase production and the relationship between extracellular enzyme and in vitro susceptibility of Mycobacterium fortuitum to beta-lactam antibiotics have been studied. To this end we used a panel of stable nitrosoguanidine-induced mutants of M. fortuitum derived from the parental strain ATCC 19542
-
28. Efficacy of prophylaxis with beta-lactams and beta-lactam-beta-lactamase inhibitor combinations against wound infection by methicillin-resistant and borderline-susceptible Staphylococcus aureus in a guinea pig model.
Although some beta-lactams and beta-lactam-beta-lactamase inhibitor combinations exhibit activity against methicillin-resistant Staphylococcus aureus, there remains the concern that therapeutic failures may result from the selection of resistant subpopulations. The prophylactic use of these antibiotics in clean surgery, however, may prove adequate since woun
-
29. Beta-lactam resistance in Aeromonas spp. caused by inducible beta-lactamases active against penicillins, cephalosporins, and carbapenems.
Use of cefoperazone in a patient with Aeromonas caviae in the respiratory tract selected a mutant that constitutively produced beta-lactamase. This mutant, in contrast to its parental strain with an inducible beta-lactamase, showed enhanced resistance to newer cephalosporins and aztreonam. This observation suggested that species of Aeromonas, like those of o
-
30. Coagulase-negative staphylococci resistant to beta-lactam antibiotics in vivo produce penicillin-binding protein 2a.
Strains of coagulase-negative staphylococci were tested for in vivo resistance in a rabbit model of prophylaxis of endocarditis. Regimens of nafcillin, cefazolin, cefamandole, and vancomycin were compared for efficacy in the prevention of infection caused by two methicillin-resistant strains and a susceptible strain. For the two resistant strains, vancomycin
-
31. beta-Lactam-resistant Pseudomonas aeruginosa with modified penicillin-binding proteins emerging during cystic fibrosis treatment.
The emergence of beta-lactam-resistant strains of Pseudomonas aeruginosa in a cystic fibrosis patient treated with high-dose tobramycin and piperacillin was studied. Two serotypes, M and K, were present before treatment and persisted, with changes in their beta-lactam resistance spectra, during treatment. The resistance was correlated with changes in the pen
-
32. Outer membrane permeability in Pseudomonas cepacia: diminished porin content in a beta-lactam-resistant mutant and in resistant cystic fibrosis isolates.
Since beta-lactam resistance is a feature of Pseudomonas cepacia isolates causing pulmonary infections in cystic fibrosis (CF), this study was undertaken to determine whether alterations in beta-lactam permeability mediate drug resistance in this species. A beta-lactam-susceptible non-CF isolate (strain 75-26), a resistant mutant derived from 75-26 by select
-
33. Multiply resistant mutants of Enterobacter cloacae selected by beta-lactam antibiotics.
Mutants of Enterobacter cloacae, selected in vitro with ceftriaxone, ceftazidime, carumonam, or aztreonam, fell into several distinct classes. Three mutants highly resistant to nearly all beta-lactam antibiotics were stably derepressed for beta-lactamase production. Although no other changes could be detected, virulence in a mouse septicemia model was decrea
-
34. Patterns and mechanisms of beta-lactam resistance among isolates of Escherichia coli from hospitals in the United States.
To study the national distribution of beta-lactam resistance patterns and mechanisms among Escherichia coli organisms isolated in U.S. hospitals, 652 ampicillin-resistant (Am(r)) or ampicillin-intermediate (Ami) isolates were submitted to the Centers for Disease Control from March 1983 through July 1984 by nine hospitals participating in the National Nosocom
-
35. Comparative activities of newer beta-lactam agents against members of the Bacteroides fragilis group.
A nationwide susceptibility survey of 557 isolates of the Bacteroides fragilis group was continued in 1986. The most active beta-lactam drugs were imipenem and ticarcillin-clavulanic acid, which had 0.2 and 1.7% resistance, respectively. The rank order of activity of beta-lactam drugs was imipenem, ticarcillin-clavulanic acid, cefoxitin, piperacillin, moxala
-
36. Involvement of a 43-kilodalton outer membrane protein in beta-lactam resistance of Shigella dysenteriae.
A beta-lactam-sensitive strain (C152) of Shigella dysenteriae showed two major outer membrane proteins (OMPs) with M(r)s of 43,000 and 38,000, while the clinical isolate M2 lacked the 43,000-Mr OMP, which acted as a channel for beta-lactam antibiotics. Permeability of beta-lactams across the outer membrane (OM) of M2 was lower than that across the OM of C152