Beta Lactam Resistance
Mostrando 13-24 de 307 artigos, teses e dissertações.
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13. beta-Lactamases and beta-lactam resistance in Escherichia coli.
Escherichia coli strains determining 17 different plasmid-determined beta-lactamases were tested for resistance to new broad-spectrum beta-lactam antibiotics. Several beta-lactamases demonstrated enhanced resistance to cefamandole but only low-level resistance to other agents. High production of cloned E. coli chromosomal beta-lactamase, however, provided re
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14. Emergence of cross-resistance to beta-lactam antibiotics in fecal Escherichia coli and Klebsiella strains from neonates treated with ampicillin or cefuroxime.
Both ampicillin and cefuroxime therapy of neonates selected drug- and species-dependent beta-lactam resistance patterns in fecal strains of Escherichia coli and Klebsiella spp. This was in contrast to our previous findings that ampicillin, but not cefuroxime, contributed to the emergence of beta-lactam resistance also by the promotion of nosocomial spread of
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15. Mechanism of resistance of an ampicillin-resistant, beta-lactamase-negative clinical isolate of Haemophilus influenzae type b to beta-lactam antibiotics.
The mechanism of non-beta-lactamase-mediated beta-lactam resistance in a clinical isolate of Haemophilus influenzae type b was studied. This clinical isolate showed up to a 32-fold increase in MICs of a wide variety of beta-lactams, including moxalactam and cefotaxime, although no beta-lactamase activity was detected, even after attempted induction. Transfor
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16. Resistance to beta-lactams in Mycobacterium fortuitum.
It is widely assumed that the high level of intrinsic resistance to beta-lactam antibiotics exhibited by mycobacteria results from the combination of factors including permeability to the drugs, beta-lactamase production, and affinity for penicillin-binding proteins (PBPs). We conducted an evaluation of the second and third factors by isolating nitrosoguanid
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17. Beta-lactamases and detection of beta-lactam resistance in Enterobacter spp.
Enterobacter spp. are becoming increasingly frequent nosocomial pathogens, and beta-lactam-resistant strains are on the increase, especially among isolates recovered from intensive care units. Therefore, a study was designed to characterize the beta-lactamases produced by 80 isolates of E. cloacae, E. aerogenes, E. taylorae, E. gergoviae, E. sakazakii, E. as
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18. Interaction of Vibrio cholerae cells with beta-lactam antibiotics: emergence of resistant cells at a high frequency.
Unlike other gram-negative enteric bacteria, Vibrio cholerae cells were equally susceptible to penicillin and ampicillin and in general more susceptible than Escherichia coli to most of the beta-lactam antibiotics. The turbidity of penicillin-treated cultures contained to increase exponentially for about 3 h, although the cell viability declined rapidly with
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19. Can penicillins and other beta-lactam antibiotics be used to treat tuberculosis?
An increase in the number of tuberculosis cases caused by multiple-drug-resistant strains of Mycobacterium tuberculosis has stimulated search for new antituberculous agents. Beta-lactam antibiotics, traditionally regarded as ineffective against tuberculosis, merit consideration. Four major penicillin-binding proteins (PBPs) with approximate molecular sizes o
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20. Altered permeability and beta-lactam resistance in a mutant of Mycobacterium smegmatis.
Beta-lactam resistance in mycobacteria results from an interplay between the following: (i) beta-lactamase production, (ii) affinity of the penicillin-binding proteins (PBPs) for the drugs, and (iii) permeation of the drugs. A laboratory mutant of Mycobacterium smegmatis was studied in order to evaluate the roles of these factors in beta-lactam resistance. M
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21. Correlation between antibiotic resistance, phage-like particle presence, and virulence in Rhodococcus equi human isolates.
Rhodococcus equi is a gram-positive coccobacillus that appears to be emerging as a pulmonary pathogen in AIDS patients. In four human clinical isolates, two antibiotic resistance phenotypes were found to coexist: one beta-lactam resistant and the other beta-lactam susceptible. In vitro, beta-lactam-resistant mutants were obtained at a frequency of 1 x 10(-5)
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22. In vitro comparison of Pseudomonas aeruginosa isolates with various susceptibilities to aminoglycosides and ten beta-lactam antibiotics.
Susceptibilities of 98 clinical isolates of Pseudomonas aeruginosa, including 33 strains with known mechanisms of amikacin resistance, were tested by the agar dilution method against 10 beta-lactam drugs. Ceftazidime, imipenem, and cefsulodin had the greatest activity, regardless of the aminoglycoside susceptibilities. The strains which were highly resistant
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23. Characterization of three different beta-lactamases from the Bacteroides fragilis group.
beta-Lactamases from five strains of Bacteroides fragilis and two strains of Bacteroides uniformis, all resistant to beta-lactam antibiotics, were compared by means of isoelectric focusing and enzyme kinetic measurements. beta-Lactamases from the five B. fragilis strains were identical, whereas those from the two B. uniformis strains were distinguished from
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24. In vitro activity of N-formimidoyl thienamycin, moxalactam, and other new beta-lactam agents against Bacteroides fragilis: contribution of beta-lactamase to resistance.
N-Formimidoyl thienamycin (N-F-thienamycin) and moxalactam were compared with other currently available and investigational antibiotics against 100 clinical isolates of Bacteroides fragilis by an agar dilution method. N-F-thienamycin was the most active among the beta-lactam agents tested, with a minimal inhibitory concentration for 90% of isolates (MIC90) o