Associação de acido clavulanico a cefalosporinas frente a Staphylococus aureus produtores de beta-lactamase

AUTOR(ES)
DATA DE PUBLICAÇÃO

1998

RESUMO

Since the 40 s decade, with the coming of the clinical chemotherapy, there are already reports of bacterial resistance to drugs. This resistance is preoccupying, since it becomes more and more difficult the treatment certain infections associated to the those microrganisms. Countless attempts take place in the sense of finding new drugs or associations, or still new therapies trying minimize the emergence and the resistance manifestation. In that way, the aim of this study was to evaluate the association of clavulanic acid, a `beta ´-lactamases inhibitor that usually comes associated to penicillins, to cephalosporins, in the attempt of increasing its bactericidal action against bacterias producer or not of `beta ´-lactamases. Therefore, 160 rats were used, which receive surgicaly implants of PVC sponges. After 7 days of the implants, the animais received doses previously established of cephalexin (75 and 150 mg/kg - groups 1 and 2); cephalexin + clavulanic acid (75 / 37,5 and 150/75 mg/kg - groups 7 and 8); ceftriaxone (40 and 80 mg/kg - groups 3 and 4); ceftriaxone + clavulanic acid (40 / 20 and 80 1 40 mg/kg - groups 9 and 10) and still clavulanic acid separately (20 and 60 mg/kg - groups 5 and 6). One hour after the administration, the formed tissue was retired and disposed in Petri dishes, previously inoculated with `10 POT. 8´ c.f.u. of Staphylococcus aureus (`beta ´-lactamase producers [clinical isolate] or no producers [ATCC 25923]) in Muller Hinton Agar. After 24h of incubation, the formed inhibition halos were measured and scored for posterior analysis. Parallelly to that an in vitro study of the same ex vivo associations tested was accomplished in the attempt of reproducing the results. For the tests in vitro, a scale of dilutions was accomplished contends the microrganism, media and still decreasing dilutions of the drugs to be tested, an MIC. The statistical analysis show: in the `beta ´-lactamase absence, the cephalexin presents better results than the ceftriaxone, what is inverted when the microrganism in subject is producer of `beta ´-lactamase (P<0,05). Still, the addition of clavulanic acid doesn t interfere in the antibiotic action of the drugs when there is `beta ´-lactamase absence. In presence of the enzyme, the association was shown sinergic, increasing the bactericide action of the drugs, being revealed useful when the microrganism show resistance

ASSUNTO(S)

testes de sensibilidade bacteriana medicamentos - biodisponibilidade microbiologia farmaceutica antibioticos beta-lactamicos

ACESSO AO ARTIGO

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