Ceftriaxone Minimum Inhibitory Concentrations Research Articles

Can the clinical efficacy of different antibiotic dosage regimens in gonorrhoea be predicted from the gonocidal effect of the corresponding plasma level profiles simulated in vitro?

Two different gonococcal strains with equal minimum inhibitory concentrations of ceftriaxone are exposed to continuously changing concentrations of this antibiotic simulating the ones found in man after the single intramuscular application of different doses (1,000, 250, 125, 50 and 25 mg). In general the bactericidal effect on both strains decreases more or less steadily with decreasing concentrations of ceftriaxone. One of the strains, however, shows a markedly dropped bactericidal effect as soon as the dosage is further reduced from 250 mg. These findings agree with previous experience from clinical dose-range finding studies. Thus the in vitro model presented here may be valuable for predicting both the optimum dosage and the clinical efficacy of new treatment protocols for gonorrhoea.

Ceftriaxone. A new cephalosporin with aqueous humor levels effective against enterobacteriaceae.

One- or two-gram doses of ceftriaxone were administered intravenously to 30 patients before cataract extraction. With the 1-g dose, mean aqueous humor concentrations of 0.93 and 0.88 microgram/mL were found at approximately 2 and 12 hours after administration, respectively. With the 2-g dose, a mean level of 2.47 micrograms/mL was observed at two hours; levels of more than 2 micrograms/mL were found in two patients 13 hours after administration. Both the 1- and 2-g doses thus produce aqueous humor levels many times higher than the minimum inhibitory concentration of ceftriaxone for 90% of most Enterobacteriaceae, excluding Pseudomonas. Concentrations adequate for Staphylococcus aureus and Staphylococcus epidermidis were not, however, obtained.

Penicillinase-producing Neisseria gonorrhoeae isolates from different localities in south east Asia. Susceptibility to 15 antibiotics.

Sixty four penicillinase-producing Neisseria gonorrhoeae (PPNG) and 24 non-penicillinase-producing (non-PPNG) strains isolated from six different south east Asian localities were tested by the agar dilution method against 15 antibiotics. All isolates were susceptible to spectinomycin and sulphamethoxazole-trimethoprim (19:1 ratio). A large proportion of both PPNG and non-PPNG strains showed, however, a decreased susceptibility to tetracycline, kanamycin, and erythromycin: 49% with minimum inhibitory concentrations (MICs) of tetracycline greater than or equal to 2 micrograms/ml, 34% with MICs of kanamycin greater than or equal to 32 micrograms/ml, and 80% with MICs of erythromycin greater than or equal to 2 micrograms/ml. These MIC cut-off values were chosen since they are close to the highest concentrations of these antibiotics attainable in serum after drug administration. Resistance to these antibiotics was not related to penicillinase production and does not appear to be confined to gonococci isolated from one particular locality. Strains showing resistance concurrently to two or three of these drugs were often isolated from different south east Asian countries. All eight cephalosporins tested were effective against both PPNG and non-PPNG strains. On a weight to weight basis the new cephalosporins--namely, moxalactam, cefoperazone, cefotaxime, and ceftriaxone--were the most effective. In contrast to those of cefoxitin, cefuroxime, moxalactam, and cefoperazone the MICs of cefamandole, cefotaxime, and ceftriaxone were significantly affected when the inoculum size was increased from 10(3) to 10(6) colony forming units (cfu).

COMPARATIVE STUDY OF CEFTRIAXONE AND SPECTINOMYCIN FOR TREATMENT OF UNCOMPLICATED GONORRHOEA IN MEN

Single-dose ceftriaxone, 125 mg or 250 mg intramuscularly (IM), was compared with spectinomycin, 2 g IM, for treatment of men with uncomplicated urethral or anorectal infections due to penicillinase-negative Neisseria gonorrhoeae. Cure rates were 100% for 31 and 28 men treated with 125 mg and 250 mg ceftriaxone, respectively, and 97% for 58 men given spectinomycin. Among patients followed up for ≥14 days, post-gonococcal urethritis occurred in 25% of 44 men treated with ceftriaxone and 19% of 47 given spectinomycin (p=NS). The geometric mean minimum inhibitory concentration of ceftriaxone for 79 pre-treatment isolates of N gonorrhoeae was 0·0058 μg/ml, and all strains were inhibited by ≤0·063 μg/ml. Neither drug caused perceptible toxicity, but patient acceptance was greater for ceftriaxone than for spectinomycin. Ceftriaxone in a single dose of 125 mg is effective against uncomplicated urethral or anorectal gonorrhoea in men and may become a regimen of choice for this infection.