Yale.edu

To investigate amoxicillin and metronidazole resistance of Helicobacter pylori, we compared putative resistance genes between resistant strains obtained in vitro and their sensitive parent strain. All metronidazole-resistant strains had rdxA mutations, and an amoxicillin-resistant strain had pbp1 and pbp2 mutations. By transforming PCR products of these mutated genes into antibiotic-sensitive strains, we showed that rdxA null mutations were sufficient for metronidazole resistance, while pbp1 mutations contributed to amoxicillin resistance of H. pylori.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11181392&dopt=Abstract antibiotic amoxicillin




Therapie. 2000 Nov-Dec;55(6):699-704.
[Delayed drug-induced hepatic injury. Evoking the role of amoxicillin-clavulinic acid combination]

[Article in French]

Mari JY, Guy C, Beyens MN, Ollagnier M.

Centre Regional de Pharmacovigilance de Saint-Etienne, Hopital de Bellevue, CHU de Saint-Etienne, 42055 Saint-Etienne, France.

Although infrequent, hepatitis associated with amoxicillin and clavulanic acid combination is probably underestimated. Except for cases with few symptoms, a time interval between stopping treatment and the first manifestations (jaundice in most cases), sometimes of several weeks, may hinder diagnosis. We report 9 patients who exhibited this characteristic. The delay between stopping treatment and the onset of hepatitis varied from 13 days to 6 weeks after stopping the drug. Other causes of jaundice were excluded. Male sex, advancing age, or prolonged treatment (more than 10 days) may increase the risk. Complete recovery occurs within 1 to 4 months after discontinuation of treatment. The mechanism is unclear. Clinical and biological signs of hypersensitivity may suggest an immunoallergic reaction.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11234465&dopt=Abstract antibiotic amoxicillin

nccs.res.in

Controlled drug delivery is gaining importance over the conventional methods of drug administration because of its inherent benefits. Self-regulated release from the delivery vehicle may enhance drug potency with a sustained action. The present study describes a novel hydrogel blend of polyacrylamide with chitosan for controlled delivery of antibiotics. Hydrogel was synthesized by cross-linking acrylamide-chitosan mixture (8:2 v/v) with N,N' methylene bisacrylamide. Hydrogel was characterized for surface morphology, hydrophilicity, pH-dependent swelling properties, cytotoxicity, and control release properties. Scanning electron microscopy (SEM) revealed the macroporous surface morphology of the matrix with average pore size at 104 +/- 7.61 mu. Hydrogel was found to be highly hydrophilic as assessed by octane contact angle (154.5 + 0.572) measurement. Hydrogel showed no cytotoxic effects on NIH3T3 and HeLa cells up to 40% of extract concentrations as determined by MTT and neutral red assay. This showed hydrogel biocompatibility and thus absence of deleterious effects of the hydrogel on cell viability and functionality. Hydrogels did not show any pH-dependent swelling profile, and they swelled considerably to achieve a swelling ratio of approximately 16.0 at the end of 24 hr. Amoxicillin was incorporated in the hydrogel matrix as a candidate antibiotic for release studies. In vitro release studies of amoxicillin revealed the sustained nature of delivery and matrix released 56.47 + 1.12% and 77.096 + 1.72% of amoxicillin at the end of 24 and 75 hr, respectively. Although in vivo studies are awaited, the present study provides enough documentation to consider polyacrylamide-chiotsan hydrogel as a possible candidate for controlled delivery of antibiotics.

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Am J Vet Res. 2001 Mar;62(3):326-30.
Screening method for identification of beta-lactams in bovine urine by use of liquid chromatography and a microbial inhibition test.

Musser JM, Anderson KL, Moats WA.

College of Veterinary Medicine, Department of Farm Animal Health and Resource Management, North Carolina State University, Raleigh 27606, USA.

OBJECTIVE: To develop a multiple-residue screening method for the detection of beta-lactams in bovine urine. ANIMALS: 6 clinically normal Holstein cows and 6 calves. PROCEDURE: Pooled urine obtained from cows was used as a negative-control sample or spiked with varying concentrations of 6 beta-lactam antibiotics. Urine samples were prepared for liquid chromatography by diluting 1 ml of urine with 9 ml of 0.01M KH2PO4, 0.01 M Na2PO4, and filtering. Filtrate (2,000 ml) was eluted with a mobile phase in a gradient program. A fraction corresponding to each beta-lactam of interest was collected and evaporated to < 1 ml, and water then was added to achieve a 1 ml volume. The collected fraction was tested, using a microbial inhibition test. Then, calves were fed milk spiked with a mixture of 5 beta-lactam antibiotics at a concentration 40X the FDA tolerance in milk. Three hours following the feeding, urine samples were obtained from the calves and tested, as described for the urine samples for the cows. RESULTS: The lowest concentrations of amoxicillin, ampicillin, cephapirin, cloxacillin, desfuroylceftiofurcysteine, and penicillin G that were consistently detected in urine were 100, 10, 100, 250, 1,000, and 10 ng/ml, respectively. Amoxicillin, ampicillin, cephapirin, cloxacillin, desacetylcephapirin, and penicillin G were detected in urine samples of 6/6, 5/6, 0/6, 6/6, 2/6, and 3/6 calves respectively, fed antibiotic-spiked milk. CONCLUSIONS AND CLINICAL RELEVANCE: The integrated method described can be used to detect or identify beta-lactam antibiotics in bovine urine. This method can be used to test cattle for beta-lactam residues.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11277195&dopt=Abstract antibiotic amoxicillin