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V F Thomsen

Publications and source records attributed to V F Thomsen.

8 recordsLinked to original sources
PubMed1992

Screening method for beta-lactamase substrate profiles.

A disc diffusion method, based on the idea of Klundert, for screening of substrate profiles of beta-lactamases was developed in order to perform epidemiological studies. The method was tested against 30 different reference beta-lactamases and 59 clinical isolates known to produce TEM-1, SHV-1 and BRO-1. The reproducibility and discriminating power of the disc diffusion method made it possible to differentiate between eight types of substrate profiles for the 30 reference beta-lactamases and to differentiate between TEM-1, SHV-1 and BRO-1 from clinical isolates. In combination with analytical isoelectric focusing the disc diffusion method gives a reliable identification of beta-lactamases.

Anti-Bacterial Agents↗
PubMed1992

In vitro activity of teicoplanin and vancomycin against gram-positive bacteria from human clinical and veterinary sources.

The minimum inhibitory concentration (MIC) of teicoplanin and vancomycin was determined by the agar dilution method for 186 Gram-positive bacteria from human clinical and veterinary sources. Teicoplanin MIC values were less than or equal to 4 micrograms/ml for 94% of staphylococci (group A, n = 52) and less than or equal to 2 micrograms/ml for all streptococci, enterococci, aerococci and pediococci (group B, n = 75). Seventy-eight percent of Gram-positive rods, Rhodococcus and Leuconostoc spp. (group C, n = 59) were inhibited by 4 micrograms/ml. Teicoplanin resistance (MIC greater than or equal to 16 micrograms/ml) was demonstrated for all Nocardia strains and for some strains of Lactobacillus, E. rhusiopathiae, Leuconostoc, and S. haemolyticus. Cross-resistance between teicoplanin and vancomycin was observed for all Nocardia strains and for some strains of Lactobacillus, E. rhusiopathiae, and Leuconostoc. Three methicillin-resistant S. haemolyticus strains were either resistant or intermediately susceptible to teicoplanin and susceptible to vancomycin. Eight strains (motile enterococci four, E. rhusiopathiae three and Leuconostoc sp. one) were susceptible to teicoplanin and resistant to vancomycin. Teicoplanin disc diffusion on Danish Blood Agar with NeoSensitabs (Rosco), PDM AB Biodisc and locally prepared discs revealed a wide range of zone diameters in groups B and C. The relation between MIC values and zone diameters for teicoplanin was analysed by the error-rate bounded method. Zone size interpretive criteria as suggested by the manufacturers (greater than or equal to 15 mm) produced 2.7% (95% confidence limits 0.9-6.2%) and 1.6% (95% confidence limits 0.3-4.6%) very major errors for NeoSensitabs and PDM-disc, respectively. Using a zone size breakpoint for susceptibility of greater than or equal to 25 mm for NeoSensitabs and greater than or equal to 20 mm for PDM-disc, the proportions of very major errors were 0.5% (95% confidence limits 0.0-3.0%) at the expense of 5.9% (95% confidence limits 3.0-10.3%) indeterminate strains that belonged to E. rhusiopathiae, Leuconostoc, Lactobacillus and S. haemolyticus. However, using these zone size breakpoints five major errors (beta-haemolytic streptococci, group B three, S. aureus one, Leuconostoc sp. one) were observed for NeoSensitabs and two major errors (beta-haemolytic streptococcus, group B one, Leuconostoc sp. one) were observed for PDM-disc. Susceptibility testing against teicoplanin among these taxa should therefore include a determination of MIC.

Animals↗
PubMed1991

The antibacterial activity of a siderophore. 2. The influence of deferoxamine alone and combined with ascorbic acid on the activity of antibiotics against Staphylococcus aureus.

The in vitro activity of deferoxamine (DFO) combined with cephalothin, gentamicin, cefotaxime, vancomycin, and fusidic acid, in the presence or absence of the reductant ascorbic acid (AA) was investigated against Staphylococcus aureus by a macrobroth dilution technique and killing curve kinetics. DFO and in particular DFO + AA lowered the MICs of cephalothin, gentamicin, cefotaxime, and fusidic acid for most of the strains and in some instances also the MICs of vancomycin. To characterize the interaction between DFO or DFO + AA and antimicrobials we applied the growth constants of logarithmic growth phase. Generally DFO acted synergistically with cephalothin, gentamicin, vancomycin, and fusidic acid, particularly in the presence of AA, and in some cases synergy was demonstrated with cefotaxime, too.

Anti-Bacterial Agents↗
PubMed1989

Evaluation of Stuart's transport medium containing penicillinase. An in vitro study. Brief report.

An in vitro study was performed to evaluate the value of penicillinase in Stuart's transport medium. Swabs were taken from serum broth cultures of Staphylococcus aureus, Escherichia coli and Proteus rettgeri, incubated with cefuroxime. Following 24 hours' storage in the transport medium, the recovery of P. rettgeri was significantly higher from Stuart's transport media containing penicillinase in a concentration of 100,000 units/ml, than from swabs stored in Stuart's medium without penicillinase. Although susceptible to cefuroxime, we did not find the same effect on S. aureus and E. coli, presumably because these strains had higher MIC values than the P. rettgeri strain tested.

Bacteria↗
PubMed1986

Susceptibility testing with disc diffusion for new cephalosporins: pre-diffusion revisited.

The purpose of the present study was to investigate the effect of 20-hour pre-diffusion, i.e. placing the antibiotic-containing discs on the agar for 20 hours prior to inoculation, as compared to direct diffusion, i.e. placing the discs on the agar immediately after inoculation, for the newer 3. generation cephalosporins as represented by ceftazidime and ceftriaxone. Regression lines (zone sizes vs. inhibitory concentrations, as measured by plate-dilution) were constructed for three groups of bacteria chosen because of their differences in growth characteristics on agar: E. coli (n = 50), Enterobacter sp. (n = 35), and streptococci (n = 51). The results for both cephalosporins were: 20-hour pre-diffusion produced larger zones than direct diffusion, regression studies for 20-hour pre-diffusion as compared to direct diffusion resulted in greater variation in zone sizes, numerically lower slopes, lower residual variances and higher correlation coefficients, and regression lines were significantly different for the 3 groups of bacteria with direct diffusion but not so with 20-hour pre-diffusion. Considering the interpretation of zone sizes with disc diffusion for the cephalosporins tested, 20-hour pre-diffusion was superior to direct diffusion.

Ceftazidime↗
PubMed1976

Bacteriology and antibiotics in acute suppurative otitis media.

One hundred and forty-seven patients with acute suppurative otitis media, were divided into three groups and treated with antibiotics (azidocillin, ampicillin, and cephalexin). The therapeutic effect was assessed bacterioloically by swabbing from the aural discharge and from the nasopharynx on the first, second, third, and seventh day after initiation of treatment. In addition, the concentration of antibiotic in the aural discharge and in the nasopharynx was determined. As compared with other published materials, there was a common occurrence of Haemophilus influenzae and S. Aureus. Hemolytic streptococci are less common than prior to the advent of antibiotics. Pneumococci disappeared in all cases from the aural discharge in the course of the first three days. The effect upon Haemophilus was slower. In the nasopharynx the effect was questionable, and no effect was obtained upon other bacteria. The clinical course could not be correlated to the bacterial findings except that resistant bacteria were found in all cases with persisting discharge.

Ampicillin↗