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Selection of Resistant Streptococcus pneumoniae during Penicillin Treatment In Vitro and in Three Animal Models.

Knudsen, Jenny Dahl; Odenholt, Inga LU ; Erlendsdottir, Helga; Gottfredsson, Magnus; Cars, Otto; Frimodt-Møller, Niels; Espersen, Frank; Kristinsson, Karl G. and Gudmundsson, Sigurdur (2003) In Antimicrobial Agents and Chemotherapy 47(8). p.2499-2506
Abstract
Pharmacokinetic (PK) and pharmacodynamic (PD) properties for the selection of resistant pneumococci were studied by using three strains of the same serotype (6B) for mixed-culture infection in time-kill experiments in vitro and in three different animal models, the mouse peritonitis, the mouse thigh, and the rabbit tissue cage models. Treatment regimens with penicillin were designed to give a wide range of T>MICs, the amounts of time for which the drug concentrations in serum were above the MIC. The mixed culture of the three pneumococcal strains, 107 CFU of strain A (MIC of penicillin, 0.016 µg/ml; erythromycin resistant)/ml, 106 CFU of strain B (MIC of penicillin, 0.25 µg/ml)/ml, and 105 CFU of strain C (MIC of penicillin, 4... (More)
Pharmacokinetic (PK) and pharmacodynamic (PD) properties for the selection of resistant pneumococci were studied by using three strains of the same serotype (6B) for mixed-culture infection in time-kill experiments in vitro and in three different animal models, the mouse peritonitis, the mouse thigh, and the rabbit tissue cage models. Treatment regimens with penicillin were designed to give a wide range of T>MICs, the amounts of time for which the drug concentrations in serum were above the MIC. The mixed culture of the three pneumococcal strains, 107 CFU of strain A (MIC of penicillin, 0.016 µg/ml; erythromycin resistant)/ml, 106 CFU of strain B (MIC of penicillin, 0.25 µg/ml)/ml, and 105 CFU of strain C (MIC of penicillin, 4 µg/ml)/ml, was used in the two mouse models, and a mixture of 105 CFU of strain A/ml, 104 CFU of strain B/ml, and 103 CFU of strain C/ml was used in the rabbit tissue cage model. During the different treatment regimens, the differences in numbers of CFU between treated and control animals were calculated to measure the efficacies of the regimens. Selective media with erythromycin or different penicillin concentrations were used to quantify the strains separately. The efficacies of penicillin in vitro were similar when individual strains or mixed cultures were studied. The eradication of the bacteria, independent of the susceptibility of the strain or strains or the presence of the strains in a mixture or on their own, followed the well-known PK and PD rules for treatment with ß-lactams: a maximum efficacy was seen when the T>MIC was >40 to 50% of the observation time and the ratio of the maximum concentration of the drug in serum to the MIC was >10. It was possible in all three models to select for the less-susceptible strains by using insufficient treatments. In the rabbit tissue cage model, a regrowth of pneumococci was observed; in the mouse thigh model, the ratio between the different strains changed in favor of the less-susceptible strains; and in the mouse peritonitis model, the susceptible strain disappeared and was overgrown by the less-susceptible strains. These findings with the experimental infection models confirm the importance of eradicating all the bacteria taking part in the infectious process in order to avoid selection of resistant clones. (Less)
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Contribution to journal
publication status
published
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in
Antimicrobial Agents and Chemotherapy
volume
47
issue
8
pages
2499 - 2506
publisher
American Society for Microbiology
external identifiers
  • pmid:12878511
  • wos:000184449800018
  • scopus:0041767539
ISSN
1098-6596
DOI
10.1128/AAC.47.8.2499-2506.2003
language
English
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yes
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ae4e90b6-e8d7-4c49-a084-0225eb8cfaec (old id 116363)
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http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12878511&dopt=Abstract
date added to LUP
2007-07-24 16:13:00
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2018-10-03 11:35:41
@article{ae4e90b6-e8d7-4c49-a084-0225eb8cfaec,
  abstract     = {Pharmacokinetic (PK) and pharmacodynamic (PD) properties for the selection of resistant pneumococci were studied by using three strains of the same serotype (6B) for mixed-culture infection in time-kill experiments in vitro and in three different animal models, the mouse peritonitis, the mouse thigh, and the rabbit tissue cage models. Treatment regimens with penicillin were designed to give a wide range of T>MICs, the amounts of time for which the drug concentrations in serum were above the MIC. The mixed culture of the three pneumococcal strains, 107 CFU of strain A (MIC of penicillin, 0.016 µg/ml; erythromycin resistant)/ml, 106 CFU of strain B (MIC of penicillin, 0.25 µg/ml)/ml, and 105 CFU of strain C (MIC of penicillin, 4 µg/ml)/ml, was used in the two mouse models, and a mixture of 105 CFU of strain A/ml, 104 CFU of strain B/ml, and 103 CFU of strain C/ml was used in the rabbit tissue cage model. During the different treatment regimens, the differences in numbers of CFU between treated and control animals were calculated to measure the efficacies of the regimens. Selective media with erythromycin or different penicillin concentrations were used to quantify the strains separately. The efficacies of penicillin in vitro were similar when individual strains or mixed cultures were studied. The eradication of the bacteria, independent of the susceptibility of the strain or strains or the presence of the strains in a mixture or on their own, followed the well-known PK and PD rules for treatment with ß-lactams: a maximum efficacy was seen when the T>MIC was >40 to 50% of the observation time and the ratio of the maximum concentration of the drug in serum to the MIC was >10. It was possible in all three models to select for the less-susceptible strains by using insufficient treatments. In the rabbit tissue cage model, a regrowth of pneumococci was observed; in the mouse thigh model, the ratio between the different strains changed in favor of the less-susceptible strains; and in the mouse peritonitis model, the susceptible strain disappeared and was overgrown by the less-susceptible strains. These findings with the experimental infection models confirm the importance of eradicating all the bacteria taking part in the infectious process in order to avoid selection of resistant clones.},
  author       = {Knudsen, Jenny Dahl and Odenholt, Inga and Erlendsdottir, Helga and Gottfredsson, Magnus and Cars, Otto and Frimodt-Møller, Niels and Espersen, Frank and Kristinsson, Karl G. and Gudmundsson, Sigurdur},
  issn         = {1098-6596},
  language     = {eng},
  number       = {8},
  pages        = {2499--2506},
  publisher    = {American Society for Microbiology},
  series       = {Antimicrobial Agents and Chemotherapy},
  title        = {Selection of Resistant Streptococcus pneumoniae during Penicillin Treatment In Vitro and in Three Animal Models.},
  url          = {http://dx.doi.org/10.1128/AAC.47.8.2499-2506.2003},
  volume       = {47},
  year         = {2003},
}