Review of Pharmacokinetic, Pharmacodynamic and Clinical Studies with a Modern Combination of Amoxicillin/Sulbactam

Amoxicillin/sulbactam is a modern antimicrobial combination. This combination proved to be useful for the treatment of several infections caused by different microorganisms, mainly with the beta-lactamase-producing species. In this review we present the most relevant pharmacokinetic, pharmacodynamic and clinical information associated with its use.

Argentinian collaborative study on prevalence of erythromycin and penicillin susceptibility in Streptococcus pyogenes. The Argentinian Streptococcus Study Group

Two monthly studies on the prevalence of penicillin and erythromycin susceptibility of Streptococcus pyogenes were performed in May and October of 1994 in Argentina. A total of 58 centers from 27 cities participated in these studies. A total of 1072 isolates were tested by a diffusion method, although 595 isolates were tested both by the diffusion and an agar dilution method (n = 1767 isolates). No penicillin-resistant streptococci were found in our study (MIC100 = 0.03 microgram/ml). Only four isolates were confirmed as erythromycin resistant S. pyogenes (prevalence 0.14 and 0.28% in May and October 1994, respectively). Resistance in three isolates was due to an inducible mechanism, although in one strain a different phenotype was observed.

[Efficacy of gentamycin combined with beta-lactam antibiotics against penicillin-resistant and non-resistant Streptococcus agalactiae]

BACKGROUND

Evaluation of the incidence, tolerance and the bactericidal activity against penicillin, ampicillin, cefotaxime, gentamicin and the combination of penicillin plus gentamicin, ampicillin plus gentamicin, cefotaxime plus gentamicin and cefotaxime plus ampicillin in 22 clinical isolates of Streptococcus agalactiae.

METHODS

Killing curves were performed. The concentrations of antibiotics was selected taking into account its level in cerebrospinal fluid.

RESULTS

We detected 5 (22.7%) tolerant strains to penicillin and ampicillin and 2 of them (9.0%) were also tolerant to cefotaxime. Bactericidal activity was seen in a 100% of the strains against the association penicillin plus gentamicin, ampicillin plus gentamicin and cefotaxime plus gentamicin, being greater than the bactericidal activity against cefotaxime (77.3%), penicillin, ampicillin and cefotaxime plus ampicillin (54.5% respectively).

CONCLUSIONS

Considering the high incidence of tolerance and the deficient bactericidal activity of the beta-lactam antibiotics against tolerant and no tolerant strains, it seems necessary to include gentamicin in the treatment of Streptococcus agalactiae severe infections. Several studies of experimental models must be performed to verify in vivo, the in vitro results.