Biomedical subjects

R B Provonchee

Publications and source records attributed to R B Provonchee.

3 recordsLinked to original sources

PubMed1977

Synergistic activity of trimethoprim and amikacin against gram-negative bacilli.

The in vitro effect of trimethoprim on the inhibitory and bactericidal activity of amikacin against 20 strains each of Klebsiella pneumoniae and Serratia marcescens, 15 strains of Escherichia coli, and 10 strains of Pseudomonas aeruginosa was examined by the checkerboard technique in microtiter plates. Trimethoprim had a synergistic effect on the inhibitory and bactericidal activity of amikacin against the majority of non-pseudomonas strains tested. The mean +/- standard deviation fractional inhibitory concentration indexes were 0.59 +/- 0.19 for the Klebsiella strains, 0.48 +/- 0.18 for the Serratia strains, and 0.60 +/- 0.22 for the E. coli strains tested. Respective mean +/- standard deviation fractional bactericidal concentration indexes for these organisms were 0.55 +/- 0.17, 0.54 +/- 0.29, and 0.61 +/- 0.22. A total of 40% of the Klebsiella strains, 80% of the Serratia strains, and 46% of the E. coli strains had a fractional inhibitory concentration equal to or less than 0.25 for both of these antimicrobial agents and were considered to be synergistically inhibited by the combination. By applying this criterion to bactericidal activity, synergy was demonstrated against 50, 65, and 46% of these strains, respectively. All of the Enterobacteriaceae tested were inhibited by clinically achievable concentrations of trimethoprim and amikacin. Antagonism was not demonstrated with any of the organisms tested. Trimethoprim had no antibacterial effect on the Pseudomonas strains and did not alter amikacin's activity against these bacteria.

Amikacin↗

PubMed1976

Effect of clindamycin on the in vitro activity of amikacin and gentamicin against gram-negative bacilli.

The in vitro effect of clindamycin on the inhibitory and bactericidal activity of amikacin (BB-K8) and gentamicin against Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa was examined by the checkerboard technique in microtiter plates. Clindamycin (15 mug/ml) produced statistically significant increases in the minimal bactericidal concentrations of amikacin and gentamicin against E. coli and Klebsiellae at 2 and 4 h of incubation. The minimal bactericidal concentration against P. aeruginosa was not affected. Higher concentrations of clindamycin (20 to 25 mug/ml) reduced the minimal inhibitory and bactericidal concentrations of amikacin and gentamicin for E. coli at 18 h of incubation. The synergistic bactericidal activity of amikacin and carbenicillin against E. coli, but not P. aeruginosa, was also inhibited slightly by clindamycin (15 mug/ml). The clinical implications of this inhibition of the early bactericidal in vitro activity of aminoglycosides by clindamycin remain to be determined. Although these in vitro results have not been studied in clinical infections, it is conceivable that slight interference in early bacterial killing could alter the outcome of infection in the immunosuppressed patient.

Amikacin↗

PubMed1974

Rapid method for determining serum bactericidal activity.

To screen large numbers of sera, a method was devised which utilizes the Steers-Foltz replicator which is usually used to determine minimal inhibitory concentration for antibiotics. Each of the wells (9 by 15 mm) of the replicator is filled with 0.06 ml of serum, 0.02 ml of a 10(5) suspension of organisms, and 0.02 ml of diluent (tris(hydroxymethyl)aminomethane-hydrochloride buffer, pH 8.4). The mixtures are incubated for 3 h, and samples are taken at 0, 1, 2, and 3 h by stamping duplicate nutrient agar plates (approximately 0.04 ml from each well). Plates are incubated overnight, and bactericidal activity is estimated by visual inspection of bacterial growth at each site for each sampling time. Results obtained with 28 serum-organism pairs paralleled standard pipetting-pour plate methods. The replicator method for determining bactericidal activity allows for the testing of a large number of samples and requires negligible amounts of serum.

Blood Bactericidal Activity↗