In-vitro susceptibilities of species of the Bacteroides fragilis group to newer beta-lactam agents.
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The in-vitro activities of imipenem and four beta-lactam-beta-lactamase inhibitor combinations were tested against 816 strains of the Bacteroides fragilis group, and compared with other anti-anaerobic agents. None of the strains was resistant to metronidazole, and only one was resistant to chloramphenicol. Mezlocillin and piperacillin were moderately active, while clindamycin was the least active. Rates of resistance varied between various species. The new beta-lactam agents tested showed excellent activity; piperacillin-tazobactam and imipenem were the most active. The emergence of strains that are resistant to these agents, observed in this study, suggests there is a need to perform periodic antimicrobial susceptibility tests. (+info)
AS-924, a novel bifunctional prodrug of ceftizoxime.
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To improve the oral absorption of ceftizoxime (CZX), 7beta-[(Z)-2-(2-aminothiazol-4-yl)-2-methoxyiminoacetamido]- 3-cephem-4- carboxylic acid, we synthesized and evaluated a novel series of bifunctional prodrugs, in which L-alanine was introduced into the aminothiazole-oxime moiety at the C-7 position of the various lipophilic esters of CZX. Among these prodrugs, pivaloyloxymethyl 7beta-[(Z)-2-(2-(S)-alanylaminothiazol-4-yl)-2-methoxyiminoa cetamido]-3-cephem-4-carboxylate hydrochloride (ceftizoxime alapivoxil, AS-924) was well absorbed after oral administration in experimental animals and showed potent therapeutic effects in mice infected with gram-positive and gram-negative bacteria. (+info)
Predicting susceptibility of Streptococcus pneumoniae to ceftriaxone and cefotaxime by cefuroxime and ceftizoxime disk diffusion testing.
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In this study, disk diffusion testing with ceftizoxime and cefuroxime was evaluated for use in predicting the susceptibility of Streptococcus pneumoniae to ceftriaxone and cefotaxime. Of the 194 isolates included in this study, 138 were susceptible, 34 were intermediate, and 22 were resistant to cefotaxime by MIC testing; 138 isolates were susceptible, 35 were intermediate, and 21 were resistant to ceftriaxone by MIC testing. A zone of inhibition around the cefuroxime disk of >/=32 mm correctly categorized 101 of 138 isolates as susceptible to cefotaxime and ceftriaxone. A zone of inhibition around the ceftizoxime disk of >/=26 mm correctly categorized 111 of 138 isolates as susceptible to cefotaxime and 114 of 138 as susceptible to ceftriaxone. We conclude that disk diffusion can separate S. pneumoniae isolates susceptible to ceftriaxone and cefotaxime from those that are not susceptible. Isolates not falling into the susceptible category by disk diffusion require additional testing to determine the MIC. (+info)
Gradual alterations in cell wall structure and metabolism in vancomycin-resistant mutants of Staphylococcus aureus.
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In five vancomycin-resistant laboratory step mutants selected from the highly and homogeneously methicillin-resistant Staphylococcus aureus strain COL (MIC of methicillin, 800 microg/ml; MIC of vancomycin, 1.5 microg/ml), the gradually increasing levels of resistance to vancomycin were accompanied by parallel decreases in the levels of methicillin resistance and abnormalities in cell wall metabolism. The latter included a gradual reduction in the proportion of highly cross-linked muropeptide species in peptidoglycan, down-regulation of the production of penicillin-binding protein 2A (PBP2A) and PBP4, and hypersensitivity to beta-lactam antibiotics each with a relatively selective affinity for the various staphylococcal PBPs; the PBP2-specific inhibitor ceftizoxime was particularly effective. (+info)
Effect of supplements with lactic acid bacteria and oligofructose on the intestinal microflora during administration of cefpodoxime proxetil.
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Thirty healthy volunteers in three groups participated in a study of the effect on the intestinal microflora of oral supplementation with Bifidobacterium longum, Lactobacillus acidophilus and oligofructose, an indigestible oligosaccharide, during oral administration of cefpodoxime proxetil bd for 7 days. Those in group A also received an oral supplement with c.1011 cfu of B. longum BB 536 and L. acidophilus NCFB 1748 and 15 g oligofructose daily, those in group B received a supplement with oligofructose only and those in group C received placebo, for 21 days. In all three groups there was a marked decrease in aerobic microorganisms, involving mainly a rapid and almost complete disappearance of Escherichia coli (P: < 0.05) during antimicrobial administration and, thereafter, an overgrowth of enterococci (P: < 0.05). The number of intestinal yeasts also increased significantly (P: < 0.05) in groups A and B over the same period. There was a dramatic decrease in anaerobic microorganisms on day 4 of administration, mainly caused by loss of bifidobacteria (P: < 0.05) in all groups. The number of lactobacilli also decreased but was significantly higher in group A than in group C at the end of cefpodoxime proxetil administration. Clostridium difficile was found in only one person from group A, but six persons each in groups B and C. Of the bifidobacterial strains isolated from the faecal samples in group A, one was similar to the strain of B. longum administered, but most volunteers were colonized by several different strains of B. longum during the investigation period. The administered strain of L. acidophilus was recovered from six patients in group A. (+info)
Detection of extended-spectrum beta-lactamases in klebsiellae with the Oxoid combination disk method.
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The Oxoid combination disk method for detecting extended-spectrum beta-lactamases (ESBLs) depends on comparing the inhibition zones of cefpodoxime (10-microg) and cefpodoxime-plus-clavulanate (10- plus 1-microg) disks. The presence of clavulanate enlarged the zones for all of 180 ESBL-producing klebsiellae by >/=5 mm, whereas zones for cefpodoxime-susceptible isolates and cefpodoxime-resistant isolates with AmpC and K1 beta-lactamases were enlarged by +info)
Improved detection of methicillin-resistant Staphylococcus aureus using phenyl mannitol broth containing aztreonam and ceftizoxime.
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We tested a phenyl mannitol broth containing ceftizoxime and aztreonam (PHMB(+)) for detection of methicillin-resistant Staphylococcus aureus (MRSA) with reference MRSA strains and, subsequently, with clinical samples (n = 1,098). All reference MRSA strains induced color change in PHMB(+) after 24 to 72 h of incubation. In a clinical setting, 40 MRSA strains were detected with PHMB(+), compared with only 23 detected with a routine method. Thus, this selective broth significantly (P < 0.001) improved the rate of MRSA detection. (+info)
Effect of experimental renal failure on the pharmacodynamics of cefoselis-induced seizures in rats.
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We investigated the effect of infusion rate and experimental renal failure on the pharmacodynamics of cefoselis (CFSL)-induced seizures. As an animal model of CFSL-induced seizures, male Wistar rats received an intravenous infusion of CFSL at one of three different rates (1.4-5.8 g/h/rat) until the onset of maximal seizures (which occurred after 8.0 to 36.0 min of infusion). Samples of cerebrospinal fluid (CSF), blood (for serum), and brain were obtained immediately after stopping infusion of CSFL. The serum concentration of CFSL at the onset of seizures increased with increasing infusion rate, but brain and CSF concentrations of CFSL at the onset of seizures were not affected by the infusion rate. Ureter-ligated (UL) and control rats received an intravenous infusion of CFSL at 1.4 g/h/rat until the onset of seizures. Then the same procedure as used to determine the effect of infusion rate on the concentrations of CFSL was carried out. Renal failure was associated with a significant decrease in the amount of CFSL required to induce seizures. Serum, brain, and CSF concentrations of CFSL in UL rats were significantly lower than those in control rats. These results indicate that the experimental strategy and animal model in this investigation would be useful to assess the effects of diseases and other variables on the pharmacodynamics of CFSL-induced seizures and that renal failure is one of the risk factors for neurotoxicity of CFSL. (+info)