From May 1996 to September 1997, 615 Pseudomonas aeruginosa strains isolated from patients in intensive care units collected from different Italian laboratories were studied. The susceptibility of piperacillin/tazobactam, in comparison with other antipseudomonal antibiotics, to their NCCLS breakpoints was evaluated: amikacin 79. 6%, carbenicillin 67.0%, ceftazidime 73.4%, ciprofloxacin 55.8%, imipenem 64.1%, piperacillin 88.1%, piperacillin/tazobactam 92.4% and ticarcillin/clavulanic acid 69.0%. Seventy-three strains were selected because of their resistance to piperacillin and the mechanisms underlying such a resistance were investigated. Isoelectric focusing and hydrolysis assays revealed the presence of 15 plasmid-mediated beta-lactamases. Chromosomal beta-lactamase derepression was demonstrated in 34 isolates. The remaining 24 piperacillin-resistant strains did not produce beta-lactamases and an 'intrinsic mechanism' of resistance was inferred. The piperacillin/tazobactam combination restored resistance in 25 piperacillin strains. Nine of these were derepressed for chromosomal beta-lactamase, 8 showed impermeability and 8 showed plasmid enzymes.

Drug Therapy, Combination↗

PubMedDate not supplied

Interaction of cefotetan and the metallo-beta-lactamases produced in Aeromonas spp. and in vitro activity.

Aeromonas spp. are increasingly being recognized as human pathogens. The presence of metallo-beta-lactamases in these organisms represents a potential problem in antimicrobial therapy. Mechanism-based inactivators of beta-lactamases are used to overcome the resistance of clinical pathogens to beta-lactam antibiotics, but no clinical useful inhibitors of the metallo-beta-lactamases are presently known. Studying the interaction between cefotetan and Aeromonas spp. producing metallo-beta-lactamase activity, we observed that cefotetan behaved as a transient inactivator for both the crude extracts of Aeromonas strains and the purified enzymes from Aeromonas hydrophila AE036 and Aeromonas schubertii MNSA20. The direct hydrolysis of cefotetan showed that it was a poor substrate for both purified enzymes. In view of the minimum inhibitory concentrations, cefotetan shows to be a useful antimicrobial agent against Aeromonas spp.

Aeromonas↗

PubMedDate not supplied

[Leukocyanidines and collagenases: in vitro enzyme inhibition activity].

OBJECTIVE: The matrix metalloproteinases (MMPs) play a key role in the extracellular matrix turnover. This protein family has been involved in some ocular pathologies such as glaucoma, diabetic retinopathy, macular degeneration, vitreous degeneration and corneal stroma ulceration cleaving all the matrix components. In the present study we evaluated the action of leucocyanidin from Vitis vinifera seeds as non toxic inhibitor of these proteinases. MATERIALS AND METHODS: To this purpose we used a fluorimetric method to evaluate the effect of this substance on the collagenase activity. We evaluated "in vitro" the inhibitory potency of the tested drug on type III collagenase activity, and the recover of the metalloprotease activity upon removal by dialysis of the inhibitor. RESULTS: The leucocyanidines extract (minimum procyanidines value of 95.0) resulted to be a good collagenase activity inhibitor showing an inhibition constant value, Ki, of 82 microM, evident index of affinity between the extract and the enzyme. Furthermore, the dialysis experiments demonstrated that the inhibitory effect persisted 24 h later, probably because the extract forms a stable complex with the enzyme. CONCLUSIONS: These results should be related to the pharmacokinetic profile of leucoanthocyanins, a family of natural polyphenols belonging to the class of bioflavonoids of grape seds extract (Vitis vinifera L.).

Collagenases↗

PubMedDate not supplied

[Metalloproteinase inhibition: therapeutic application in rheumatic diseases].

PURPOSE: Matrix metalloproteinases (MMPs) play an important role in the degradation of articular cartilage in several diseases, including osteorthritis and rheumatoid arthritis. Aiming at developing new drugs with selective inhibiting action against enzyme damaging the extracellular matrix, research is mainly directed towards the: 1) development of new drugs with specific inhibitory effect on MMPs; 2) better understanding of the pharmacologic profile of drugs already used in the treatment of rheumatic diseases, in order to identify those having an inhibiting action on degradative enzymes. MATERIALS AND METHODS: The interaction between rifamycins and collagenase type XI were studied using a fluorogenic substrate MOCAc-Pro-Leu-Gly-Leu-A2pr(Dnp)-Ala-Arg-NH2. RESULTS: In our experimental conditions rifamycins showed a marked inhibition capacity with a IC50 ranging from 13 to 20.7 microM. This inhibition was reversible after extensive dialysis. CONCLUSIONS: Our results indicate that the effects of rifamycins in rheumatoid arthritis may correlate to the inhibitory activity of these molecules on collagenase activity.

Arthritis, Rheumatoid↗

PubMedDate not supplied

Group report: representations in natural and artificial systems.

Explore the source record for details and available documents.

Animals↗