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K Fuursted

Publications and source records attributed to K Fuursted.

35 records · Page 2Linked to original sources
PubMed1995

DNA fingerprinting and phenotyping of Mycobacterium tuberculosis isolates from human immunodeficiency virus (HIV)-seropositive and HIV-seronegative patients in Tanzania.

With the purpose of determining whether the risk of infection with a particular clone of Mycobacterium tuberculosis is influenced by the human immunodeficiency virus (HIV) status of the host, we analyzed and compared 68 mycobacterial isolates obtained from HIV-seropositive patients with tuberculosis (TB) in Dar es Salaam, Tanzania, with 66 mycobacterial isolates obtained from HIV-seronegative patients with TB in the same geographical region by using both DNA fingerprinting and classical phenotyping methods. One hundred one different IS6110 fingerprinting patterns were observed in the 134 isolates. The level of diversity of the DNA fingerprints observed in the HIV-seropositive group was comparable to the level of the diversity observed in the HIV-seronegative group. Resistance to a single anti-TB drug was found in 8.8% of the tested isolates, and 3.2% of the isolates were resistant to more than one anti-TB drug. The drug susceptibility profiles were not significantly difference between the two groups of isolates compared in the present study. Phenotypic characteristics which classify M. tuberculosis strains as belonging to the Asian subgroup correlated with a low IS6110 copy number per isolate. However, the occurrence of Asian subgroup strains was not associated with the HIV status of the patients. The results of the study suggested an equal risk of infection with a defined M. tuberculosis clone for HIV-seropositive and HIV-seronegative individuals.

AIDS-Related Opportunistic Infections↗
PubMed1993

Comparison of growth and susceptibility testing of pyrazinamide in different Bactec media using strains of the M. tuberculosis complex.

The aim of this study was to evaluate and compare growth and susceptibility testing of pyrazinamide (pza) in different Bactec media using 85 strains of the M. tuberculosis complex. Fifty-four were clinical isolates of M. tuberculosis, of which 34 strains were selected as they failed to grow in primary pza susceptibility testing. Fourteen were strains of M. bovis, 10 were different strains of M. bovis BCG, five were strains of M. africanum, and two were strains of M. microti. The following Bactec media were evaluated: (1) Bactec PZA test medium, (2) acidified Bactec 12B medium with pH reduced to 5.6, (3) acidified 12B medium supplemented with fresh egg yolk, (4) acidified 12B medium supplemented with a commercial egg yolk enrichment. Demonstration of pyrazinamidase activity was included for comparison. All strains of M. tuberculosis, M. microti and M. africanum were inhibited by pza at 100 micrograms/ml, and all strains of M. bovis and M. bovis BCG were found to be resistant to pza at 100 micrograms/ml. Bactec PZA test medium supported growth for all 85 strains tested. The two egg yolk-supplemented media supported growth in all strains except one strain of M. microti, and acidified but otherwise unsupplemented Bactec 12B medium supported growth in 64 strains (75%). A pza sensitivity test result could be obtained within one week in > 79% of strains. An overall correlation of 89% between susceptibility to pza and demonstration of pyrazinamidase activity was demonstrated.

Amidohydrolases↗
PubMed1992

Detection of mycobacteria from blood and bone marrow: a decade of experience.

This study reports our experience with methods used at our department from 1981 through 1990 for detection of mycobacteria in blood and bone marrow specimens. Direct inoculation on Lowenstein Jensen media was replaced by Isolator lysis-centrifugation followed by inoculation on conventional solid media, and the Bactec 12B and Bactec 13A systems. A total of 3033 specimens were analyzed. A total of 137 mycobacterial isolates were obtained from 42 patients, all HIV-positive except one. Mycobacteremia caused by M. avium-intracellulare (83%), M. tuberculosis, M. scrofulaceum and M. kansasii was found. Of 680 blood specimens tested by the last three methods, 7.6% were found to be positive by at least one method and revealed recovery rates of 6.8% for the Isolator-solid media system, 3.4% for the Isolator-12B system and 6.9% for the 13A system (all isolates MOTT). Mean detection times for 21 cultures found positive by all three methods were 23.6, 23.3 and 17.7 days for the Isolator-solid media, Isolator-12B and 13A systems, respectively, with a significantly shorter detection time for the 13A system. Low degree (less than 1 cfu/ml) mycobacteremia (MOTT) caused delay in the Isolator-solid media and the 13A systems and no detection in the Isolator-12B system. Antituberculous therapy significantly prolonged the detection times for MOTT in the 13A system in contrast to the other systems.

Bacteremia↗
PubMed1992

Susceptibility of strains of the Mycobacterium tuberculosis complex to fusidic acid.

The activity of fusidic acid was studied in 40 strains of M. tuberculosis (of which 20 strains were mono- or multiresistant to standard antituberculosis drugs) and 10 strains of M. bovis. Minimum inhibitory concentration (MIC) was determined by the radiometric (BACTEC) broth method. The MIC for the 50 strains varied between 8 and 32 mg/l, with a MIC90 of 16 mg/l for M. tuberculosis and a MIC90 of 32 mg/l for M. bovis. Minimal bactericidal concentration (MBC, defined as the lowest concentration of fusidic acid which killed 99% or more of the population) varied between 32 mg/l and 500 mg/l, with a MBC90 of 250 mg/l for M. tuberculosis and 500 mg/l for M. bovis. No cross-resistance to other antituberculosis drugs (ethambutol, isoniazid, rifampicin, streptomycin, pyrazinamide, ofloxacin, ciprofloxacin) was observed as strains resistant to one or more standard antituberculosis drugs were as susceptible to fusidin as sensitive strains of M. tuberculosis. No synergism or antagonism could be demonstrated when fusidic acid was combined with either ethambutol, isoniazid, rifampicin or streptomycin against strains of M. tuberculosis resistant to one or more standard antituberculosis drugs. Addition of pooled human serum to the medium increased both MIC and MBC by factors of 4 and 8 at serum concentrations of 10% and 50%, respectively. Single-step mutation to high-level resistance to fusidic acid at a frequency of less than 1.7 x 10(-8) could be readily selected at four times the MIC. These fusidic acid-resistant organisms had a generation time 2.0-2.7 x longer than their parent organisms.

Drug Combinations↗
PubMed1989

Evaluation of the combination effects of ampicillin or vancomycin combined with streptomycin, gentamicin, tobramycin or netilmicin against enterococci.

Seven strains of Streptococcus faecalis, of which two possessed high-level resistance to streptomycin (MIC greater than or equal to 2000 mcg/ml), and two strains of Streptococcus faecium were evaluated with respect to killing-effect and duration of post-antibiotic effect (PAE) of ampicillin and vancomycin in combination with streptomycin, gentamicin, tobramycin and netilmicin. No synergistic combination effects were seen with the two strains highly-resistant to streptomycin or with the two Streptococcus faecium strains to netilmicin and tobramycin. When these strains were excluded, no significant difference in average killing could be detected between the four aminoglycosides. The mean prolongation in recovery period of susceptible strains was significantly longer with combinations of ampicillin and netilmicin or streptomycin as compared with either gentamicin or tobramycin. A similar relationship was seen for combinations of vancomycin with the four aminoglycosides.

Ampicillin↗
PubMed1989

Synergism and mechanism of subinhibitory concentration of streptomycin on Streptococcus faecalis.

The influence of various incubation conditions on synergism with cell wall-active agents combined with streptomycin was studied in a Streptococcus faecalis strain. It could be shown that both a synergistic increased killing effect and a synergistic prolongation of post-antibiotic effect (PAE) were not dependent on an active process, as they occurred both in an anaerobic atmosphere and when an electron transport inhibitor (sodium azide) was added to the media. Moreover, it was demonstrated that if a drug, alone or in combination with streptomycin, had a PAE, there was an increased susceptibility to a subinhibitory concentration of streptomycin (1/4xMIC) when added to a culture recovering from its PAE. These findings confirm the commonly held belief in a mechanistic mechanism of synergism: That cell wall-active agents modify in some way the cell-envelope, thereby enhancing aminoglycoside uptake and killing in Streptococcus faecalis.

Ampicillin↗
PubMed1989

Further studies on post-antibiotic effect and synergism in two strains of Streptococcus faecalis.

The differences in the synergistic potential for either killing effect or increase in duration of post-antibiotic effect (PAE) seen with various beta-lactam-aminoglycoside combinations in two strains of Streptococcus faecalis were further studied to examine this relationship in more detail. It was seen that a strain which produced a synergistic increase in recovery period (PAE greater than or equal to 0.5 h), comparing the beta-lactam antibiotics alone and when combined with streptomycin, showed increased sensitivity (greater than or equal to 1 log10 reduction in viable counts) to a subinhibitory concentration of streptomycin added to a culture recovering from the PAE; this was not demonstrated with a strain showing no increase in PAE when briefly exposed to a combination therapy, although its corresponding killing curve was clearly synergistic. Moreover, it was seen that the differences in the synergistic prolongation of recovery period when combining various aminoglycosides at 1/4 x MIC with ampicillin were consistent with the different duration of PAE with the particular aminoglycoside alone at the MIC.

Ampicillin↗
PubMed1988

Outbreak of infection with Achromobacter xylosoxidans from contaminated intravascular pressure transducers.

Achromobacter xylosoxidans contaminating transducers caused 15 cases of hospital infection. In the eight patients with bacteraemia the interval from inoculation to fever was an average of 6.6 days. All the infected patients recovered. Computerization of laboratory records allowed retrieval of previous isolates, and review of clinical records focused the problem on patients with cardiac and aortic diseases. The problem arose from the re-use of disposable equipment after disinfection with a benzalcone.

Aged↗
PubMed1988

Synergistic effect of ampicillin or vancomycin in combination with decreasing concentrations of streptomycin against enterococci.

The extent of synergistic killing and duration of the post-antibiotic effect (PAE) was evaluated in streptomycin-susceptible strains of Streptococcus faecalis and Streptococcus faecium with 20 mcg/ml of ampicillin or 10 mcg/ml of vancomycin in combination with decreasing concentrations of streptomycin (20, 10, 5, 2, 1, 0.5 mcg/ml). The bactericidal activity or duration in recovery period declined progressively in a linear pattern with decreasing concentrations of streptomycin. One log10 or greater reduction in viable counts was seen with streptomycin concentrations of 2 mcg/ml or higher with both ampicillin and vancomycin. A synergistic increase in recovery period (PAE greater than or equal to 0.5 h) of ampicillin or vancomycin was observed with concentrations of streptomycin in excess of 2 mcg/ml and 1 mcg/ml, respectively. These results suggest that lower dosage of streptomycin in the therapy of enterococcal infections will probably result in a higher relapse rate.

Ampicillin↗
PubMed1988

Comparative killing activity and postantibiotic effect of streptomycin combined with ampicillin, ciprofloxacin, imipenem, piperacillin or vancomycin against strains of Streptococcus faecalis and Streptococcus faecium.

Nine strains of Streptococcus faecalis and Streptococcus faecium were studied with respect to ampicillin, ciprofloxacin, imipenem, piperacillin, vancomycin and streptomycin. Two strains were highly resistant (MIC greater than or equal to 2,000 micrograms/ml) to streptomycin. Evaluation and comparison of the killing activity with killing curves, and duration of the postantibiotic effect (PAE) after exposure for 1 h with regrowth curves was done with combinations of antibiotics or alone. The overall killing effect of ciprofloxacin with streptomycin was antagonistic, whereas synergism (greater than or equal to one log10 decrease in viable counts) was observed in streptomycin-susceptible strains with combinations of streptomycin and ampicillin, imipenem, piperacillin or vancomycin. In addition, prolongation of PAE (greater than or equal to 0.5 h) was seen only in streptomycin-susceptible strains. Thus, seven (100%) strains showed a synergistic increase in PAE to combinations with ampicillin and vancomycin, three (43%) to imipenem, four (57%) to piperacillin, but none to the combination of streptomycin and ciprofloxacin. A significant correlation was observed between the magnitude of increased killing and the extent of increase in recovery period with combinations of streptomycin with either ampicillin or vancomycin.

Ampicillin↗
PubMed1987

Post-antibiotic effect of ciprofloxacin on Pseudomonas aeruginosa.

The post-antibiotic effect of ciprofloxacin on five strains of Pseudomonas aeruginosa was examined. Ciprofloxacin demonstrated rapid bactericidal action at concentrations achievable in serum. After removal of the drug persistent suppression of bacterial growth followed by regrowth was observed for all strains after exposure of the organisms to various concentrations of ciprofloxacin for limited periods of time (0.25-3 h). The duration of this post-antibiotic effect increased with the concentration of the drug and duration of exposure up to a point of maximal response. This point was reached after approximately 2.2 h using a ciprofloxacin concentration 5-10 times the MIC and 1-2 h of treatment.

Ciprofloxacin↗
PubMed1987

Analysis of the interaction between piperacillin and ciprofloxacin or tobramycin against thirteen strains of Pseudomonas aeruginosa, using killing curves.

Time-kill studies were made with thirteen strains of Pseudomonas aeruginosa, comparing the activity of ciprofloxacin plus piperacillin with the combination of tobramycin and piperacillin. Synergism was demonstrated in an equal number of strains with both combinations. No antagonism was demonstrated. The reproducibility of the killing-curve method suggests that at least two different concentrations should be used and that a decrease in viable counts below 2 log10 after 24 hours does not exclude a synergistic action.

Ciprofloxacin↗
PubMed1987

Post-antibiotic effect and killing activity of ciprofloxacin against Staphylococcus aureus.

The effect of ciprofloxacin on eight strains of Staphylococcus aureus were examined. A post-antibiotic effect was observed in all strains, varying between 1.65 and 2.75 hours, with concentration of ciprofloxacin at 5 times the Minimum Inhibitory Concentration (MIC) exposed for 1 hour. Killing-kinetic studies at 5 times the MIC showed a decrease in the numbers of organisms by approximately 2.1 log10 after 6 hours, independent of the growth phase. A significantly increased susceptibility of S. aureus to the bactericidal activity of ciprofloxacin during recovery from the PAE-phase was demonstrated.

Ciprofloxacin↗
PubMed1987

Comparison of the post-antibiotic effect of Streptococcus faecalis and Streptococcus faecium with ampicillin alone or combined with streptomycin: studies on a novel type of antimicrobial interaction.

Determination of post-antibiotic effect (PAE) and time-kill studies were made with twelve strains of Streptococcus faecalis and nine strains of Streptococcus faecium, comparing the effect of ampicillin alone with a combination of ampicillin and streptomycin at achievable serum concentrations. Bactericidal synergism (greater than or equal to one log10 decrease in viable counts) and prolongation in PAE (greater than or equal to 0.5 h) were demonstrated in all streptomycin-susceptible strains (Minimum inhibitory Concentration less than 2000 mcg/ml), whereas only one of five highly streptomycin-resistant strains exhibited a synergistic effect. A significant correlation between the magnitude of increased killing and the increase in recovery period by the combinations of ampicillin and streptomycin was demonstrated.

Ampicillin↗
PubMed1986

Population analyses of the susceptibility to ciprofloxacin of eight clinical strains of Pseudomonas aeruginosa.

Population analyses of the susceptibility to ciprofloxacin of eight strains of Pseudomonas aeruginosa, including mucoid strains and strains resistant to aminoglycosides or anti-Pseudomonas beta-lactams, were carried out. All strains were sensitive as judged by the broth-dilution technique, but four strains were found to yield resistant mutants with a frequency of less than 10(-6). Two strains yielded mutants homogeneously sensitive to ciprofloxacin at a level 8-16 times the MIC of the parent strains. Two other strains yielded mutants resistant to different higher concentrations of ciprofloxacin. One of these mutants was examined for production of ciprofloxacin-inactivating enzyme; no enzyme production could be detected. Cross-resistance was found with another quinolone antibiotic, ofloxacin, but not with aminoglycosides or beta-lactam antibiotics.

Ciprofloxacin↗
PubMedDate not supplied

Detection of penicillin resistance in Streptococcus pneumoniae by diffusion tests.

Four different diffusion tests used to detect penicillin resistance in Streptococcus pneumoniae were evaluated for 34 penicillin-susceptible pneumococci (MIC < 0.1 microgram/ml), 35 intermediate pencillin-resistant (MIC 0.1-1.0 microgram/ml) and 23 penicillin-resistant strains (MIC > 2 micrograms/ml). The 1 microgram oxacillin disk from AB Biodisk, the 1 microgram oxacillin Neo-Sensitabs from Rosco, the 5 micrograms penicillin Low Neo-Sensitabs and the penicillin E test were tested on Mueller-Hinton blood agar, PDM Antibiotic Sensitivity Medium II supplemented with blood, and Danish Blood Agar. MICs obtained by the agar dilution method were used as reference. The 1 microgram oxacillin AB Biodisk was able to separate all the penicillin-susceptible pneumococci correctly from those with reduced penicillin susceptibility (MIC > or = 0.1 microgram/ml), whereas use of the 1 microgram oxacillin Neo-Sensitabs resulted in high frequencies (14-29%) of intermediate penicillin-resistant strains interpreted as penicillin susceptible. The 5 micrograms penicillin Low Neo-Sensitabs proved completely useless for detecting penicillin resistance in pneumococci. High rates of agreement (82-93%) were found between the penicillin E test and the reference MIC determination method on all the tested media.

Diffusion↗