| 1. |
- Nyhlén, Anna
(författare)
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Antibiotics in patients on chemotherapy; aspects on pharmacokinetic and pharmacodynamic interactions with antineoplastic drugs
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aims of these studies were to investigate the pharmacokinetics of two beta-lactam antibiotics in patients with fever and cytostatic-induced neutropenia and the influence of cytostatic-induced gastrointestinal damage on the absorption of co-trimoxazole. Furthermore to study the pharmacodynamic interactions between antibiotics and antineoplastic drugs and the impact of antineoplastic drugs on the intestinal microflora. Methods: Kinetic data were obtained by model-independent methods for the beta-lactam antibiotics and by population-based methods for co-trimoxazole. Bacterial killing curves and postantibiotic effects (PAE) of different antibiotics alone and in combination with antineoplastic drugs were studied in vitro. Faecal samples were obtained from patients with acute leukaemia on different cytostatic regimens before, during and after treatment and were cultured quantitatively and qualitatively. Results and Discussion: The faster elimination of meropenem and ceftazidime in our patients compared to historical controls results in shorter times above MIC for the most common pathogens. A dose interval of 6 h seems safer than the commonly used 8 h interval, since serum concentrations should stay above MIC for most of a dose interval in these immunocompromised patients. No correlation was found between the degree of cytostatic-induced gastrointestinal damage and the bioavailability of co-trimoxazole, indicating that the dose of co-trimoxazole needs not be adjusted in these patients.Antibacterial effect and PAEs of the combinations of antibiotics and antineoplastic drugs did not differ markedly from the effects of the antibiotics alone. In the presence of 5-FU and doxorubicin, the antibacterial effect of tobramycin was increased against S. aureus. The PAEs of meropenem and ciprofloxacin against S. epidermidis were synergistically prolonged by 5-FU. This might be due to inhibition of slime production in these strains by 5-FU. The antineoplastic regimens caused only minor changes of the intestinal microflora.
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| 2. |
- Nyhlén, Anna, et al.
(författare)
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Bactericidal Effect of Combinations of Antibiotic and Antineoplastic Agents against Staphylococcus aureus and Escherichia coli.
- 2002
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Ingår i: Chemotherapy. - : S. Karger AG. - 0009-3157 .- 1421-9794. ; 48:2, s. 71-77
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Tidskriftsartikel (refereegranskat)abstract
- Background: The bactericidal effect of some antibiotic and antineoplastic agents commonly used in clinical practice was investigated to analyse whether the combinations act synergistically, have indifferent or antagonistic antibacterial effects compared to the effect of the antibiotics alone. Methods: The rate of killing of meropenem, ceftazidime and tobramycin was studied against six different strains of Staphylococcus aureus and Escherichia coli, and the results were compared to the rate of killing of the antibiotics in combination with the cytostatic drugs doxorubicin, etoposide and 5-fluorouracil (5-FU). Results: Tobramycin showed synergy against two strains of S. aureus after 3 h in the presence of 5-FU and against one strain of S. aureus in the presence of doxorubicin. Meropenem induced an antagonistic bactericidal effect against one isolate of S. aureus after 24 h. Ceftazidime expressed an indifferent bactericidal effect together with the cytostatic agents. The antineoplastic agents had no impact on the bacterial killing of any of the antibiotics against E. coli. Conclusions: Tobramycin expressed a significantly better bactericidal effect against S. aureus after 3 h in the presence of doxorubicin and 5-FU than tobramycin alone. Meropenem expressed antagonism against one clinical strain of S. aureus, but the cytostatic drugs did not affect the killing of other strains tested. Ceftazidime expressed indifferent bactericidal activity together with the antineoplastic agents.
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| 3. |
- Nyhlén, Anna, et al.
(författare)
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Impact of combinations of antineoplastic drugs on intestinal microflora in 9 patients with leukaemia.
- 2002
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Ingår i: Scandinavian Journal of Infectious Diseases. - : Informa UK Limited. - 1651-1980 .- 0036-5548. ; 34:1, s. 17-21
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Tidskriftsartikel (refereegranskat)abstract
- The impact of antineoplastic drugs on the intestinal microflora was studied in 9 patients with acute leukaemia during chemotherapy and in 5 patients also during chemotherapy-induced neutropenia. Quantitative and qualitative microbiological analyses of faecal samples obtained before and during chemotherapy showed significantly increased counts of Bacteroides spp. in 3/9 patients and, during neutropenia, significantly increased counts of yeasts in 2/5 patients; however, the intestinal microflora was stable in most patients.
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| 4. |
- Nyhlén, Anna, et al.
(författare)
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Postantibiotic effect of meropenem and ciprofloxacin in the presence of 5-fluorouracil
- 2002
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Ingår i: Chemotherapy. - 0009-3157. ; 48:4, s. 182-188
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Tidskriftsartikel (refereegranskat)abstract
- Background: The postantibiotic effect (PAE) of meropenem and ciprofloxacin was studied in the presence of the antineoplastic agent 5-fluorouracil (5-FU). The purpose of the study was to investigate whether the PAEs of the combinations differed from the PAEs of the antibiotics alone. Methods: The PAEs of the combinations of 5-FU plus meropenem or ciprofloxacin were determined with viable counts against four reference strains of Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Escherichia coli and two clinical isolates of S. epidermidis. The results were compared with the PAEs of the antibiotics drugs and 5-FU alone. The gram-positive strains were tested for slime production, both alone and in the presence of 5-FU. Results: Against two of the three tested strains of S. epidermidis, the combination of ciprofloxacin and 5-FU gave a synergistic prolongation of the PAE in comparison with the PAEs induced by the drugs alone. The combinations showed indifference against the other bacteria. The combination of meropenem and 5-FU had a synergistic PAE against one of the three tested strains of S. epidermidis and an additive effect against E coli but showed indifference against the rest of the strains. Conclusions:The presence of 5-FU did not influence the PAEs of the antibiotics against most of the tested strains, but caused a synergistic prolongation of the PAEs induced by ciprofloxacin and meropenem against some of the tested strains of S. epidermidis. 5-FU inhibited slime production in the same S. epidermidis strains, which might have contributed to the longer PAE.
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