Amoxicillin concentration in pus from abscess caused by odontogenic infection

Antibiotic abscess penetration: fosfomycin levels measured in pus and simulated concentration-time profiles

The present study was performed to evaluate the ability of fosfomycin, a broad-spectrum antibiotic, to penetrate into abscess fluid. Twelve patients scheduled for surgical or computer tomography-guided abscess drainage received a single intravenous dose of 8 g of fosfomycin. The fosfomycin concentrations in plasma over time and in pus upon drainage were determined. A pharmacokinetic model was developed to estimate the concentration-time profile of fosfomycin in pus. Individual fosfomycin concentrations in abscess fluid at drainage varied substantially, ranging from below the limit of detection up to 168 mg/liter. The fosfomycin concentrations in pus of the study population correlated neither with plasma levels nor with the individual ratios of abscess surface area to volume. This finding was attributed to highly variable abscess permeability. The average concentration in pus was calculated to be 182 +/- 64 mg/liter at steady state, exceeding the MIC(50/90)s of several bacterial species which are commonly involved in abscess formation, such as streptococci, staphylococci, and Escherichia coli. Hereby, the exceptionally long mean half-life of fosfomycin of 32 +/- 39 h in abscess fluid may favor its antimicrobial effect because fosfomycin exerts time-dependent killing. After an initial loading dose of 10 to 12 g, fosfomycin should be administered at doses of 8 g three times per day to reach sufficient concentrations in abscess fluid and plasma. Applying this dosing regimen, fosfomycin levels in abscess fluid are expected to be effective after multiple doses in most patients.

Principles of Antibiotic Penetration into Abscess Fluid

Although drainage is considered the gold standard in abscess treatment, abscesses of different sizes and locations have been successfully cured by means of antibiotic treatment alone. The penetration of an antibiotic into an encapsulated purulent lesion is limited and highly dependent on the degree of abscess maturation. In fact, in vivo pharmacokinetic data demonstrate that substantial antibiotic concentrations can be reached within abscesses in humans and animals, provided the choice of an appropriate agent and an optimal dosing regimen. However, the efficacy of antibiotics in pus may be hampered by various factors like low pH, protein binding and degradation by bacterial enzymes. This article provides a comprehensive review on conservative abscess treatment, presenting clinical data on success rates of antibiotic therapy. Antibiotic concentrations measured in abscesses of humans and animals are outlined, and theoretical considerations on the understanding of pharmacokinetics and efficacy of antibiotics in abscesses are discussed.

Cefaclor concentration in pus from abscess caused by odontogenic infection after a single oral administration

1. Cefaclor concentrations in serum and pus from abscess of odontogenic infection after a single oral administration of 500-mg cefaclor were assayed and pus concentrations were compared with minimum inhibitory concentration (MIC) of oral streptococci isolated from odontogenic infection. 2. The mean peak concentrations in serum and pus were found at identical times, 1.5 hr after administration, which were 7.22 and 0.72 micrograms/ml, respectively. 3. The mean ratio of pus:serum concentration at the peak time was 0.10. 4. Most cefaclor concentrations in pus at the peak time (seven of nine cases) exceeded the MIC for 90% of oral streptococci (0.5 micrograms/ml).