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Three Dimensional Checkerboard Synergy Analysis of Colistin, Meropenem, Tigecycline against Multidrug-Resistant Clinical Klebsiella pneumonia Isolates.

Stein C, Makarewicz O, Bohnert JA, Pfeifer Y, Kesselmeier M, Hagel S, Pletz MW - PLoS ONE (2015)

Bottom Line: Recent clinical studies of KPC-blood stream infections revealed that colistin-based combination therapy with a carbapenem and/or tigecycline was associated with significantly decreased mortality rates when compared to colistin monotherapy.Adding a third antibiotic did not result in further increased synergistic effect in these strains.Antagonism did not occur.

View Article: PubMed Central - PubMed

Affiliation: Center for Infectious Diseases and Infection Control, Jena University Hospital, Erlanger Allee 101, D-07747, Jena, Germany.

ABSTRACT
The spread of carbapenem-non-susceptible Klebsiella pneumoniae strains bearing different resistance determinants is a rising problem worldwide. Especially infections with KPC (Klebsiella pneumoniae carbapenemase) - producers are associated with high mortality rates due to limited treatment options. Recent clinical studies of KPC-blood stream infections revealed that colistin-based combination therapy with a carbapenem and/or tigecycline was associated with significantly decreased mortality rates when compared to colistin monotherapy. However, it remains unclear if these observations can be transferred to K. pneumoniae harboring other mechanisms of carbapenem resistance. A three-dimensional synergy analysis was performed to evaluate the benefits of a triple combination with meropenem, tigecycline and colistin against 20 K. pneumoniae isolates harboring different β-lactamases. To examine the mechanism behind the clinically observed synergistic effect, efflux properties and outer membrane porin (Omp) genes (ompK35 and ompK36) were also analyzed. Synergism was found for colistin-based double combinations for strains exhibiting high minimal inhibition concentrations against all of the three antibiotics. Adding a third antibiotic did not result in further increased synergistic effect in these strains. Antagonism did not occur. These results support the idea that colistin-based double combinations might be sufficient and the most effective combination partner for colistin should be chosen according to its MIC.

No MeSH data available.


Related in: MedlinePlus

Schematic set-up of three-dimensional checkerboard technique.Concentrations of each drug increase towards the arrow. The FICI values were determined for each combination: meropenem / tigecycline, meropenem / colistin, tigecycline / colistin and meropenem / tigecycline / colistin.
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pone.0126479.g001: Schematic set-up of three-dimensional checkerboard technique.Concentrations of each drug increase towards the arrow. The FICI values were determined for each combination: meropenem / tigecycline, meropenem / colistin, tigecycline / colistin and meropenem / tigecycline / colistin.

Mentions: Bacterial cells were cultivated overnight at 35°C at constant rotation (200 rpm) in MH broth. The overnight cultures were adjusted to 0.5 McFarland (equivalent to 108 CFU/mL) and diluted 1:100 with broth to obtain a 106 CFU/mL suspension. For the checkerboard assay, the broth microdilution method was modified by including some additional antibiotic concentrations. Into each well of a standard microwell plate 100 μL of the 106 CFU/mL bacterial suspensions were transferred and mixed with an equal volume of antimicrobial solution. For each strain and antibiotic the selected concentration ranges depended on previously determined MICs. In total, 11 dilution steps of meropenem, 7 dilution steps of tigecycline and 6 dilution steps of colistin were analyzed (Fig 1). The microwell plates were incubated at 35°C for 16–20 h and interpreted according to EUCAST breakpoints for Enterobacteriaceae. Each test was performed at least in duplicate and included a growth control without addition of any antibiotic.


Three Dimensional Checkerboard Synergy Analysis of Colistin, Meropenem, Tigecycline against Multidrug-Resistant Clinical Klebsiella pneumonia Isolates.

Stein C, Makarewicz O, Bohnert JA, Pfeifer Y, Kesselmeier M, Hagel S, Pletz MW - PLoS ONE (2015)

Schematic set-up of three-dimensional checkerboard technique.Concentrations of each drug increase towards the arrow. The FICI values were determined for each combination: meropenem / tigecycline, meropenem / colistin, tigecycline / colistin and meropenem / tigecycline / colistin.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4465894&req=5

pone.0126479.g001: Schematic set-up of three-dimensional checkerboard technique.Concentrations of each drug increase towards the arrow. The FICI values were determined for each combination: meropenem / tigecycline, meropenem / colistin, tigecycline / colistin and meropenem / tigecycline / colistin.
Mentions: Bacterial cells were cultivated overnight at 35°C at constant rotation (200 rpm) in MH broth. The overnight cultures were adjusted to 0.5 McFarland (equivalent to 108 CFU/mL) and diluted 1:100 with broth to obtain a 106 CFU/mL suspension. For the checkerboard assay, the broth microdilution method was modified by including some additional antibiotic concentrations. Into each well of a standard microwell plate 100 μL of the 106 CFU/mL bacterial suspensions were transferred and mixed with an equal volume of antimicrobial solution. For each strain and antibiotic the selected concentration ranges depended on previously determined MICs. In total, 11 dilution steps of meropenem, 7 dilution steps of tigecycline and 6 dilution steps of colistin were analyzed (Fig 1). The microwell plates were incubated at 35°C for 16–20 h and interpreted according to EUCAST breakpoints for Enterobacteriaceae. Each test was performed at least in duplicate and included a growth control without addition of any antibiotic.

Bottom Line: Recent clinical studies of KPC-blood stream infections revealed that colistin-based combination therapy with a carbapenem and/or tigecycline was associated with significantly decreased mortality rates when compared to colistin monotherapy.Adding a third antibiotic did not result in further increased synergistic effect in these strains.Antagonism did not occur.

View Article: PubMed Central - PubMed

Affiliation: Center for Infectious Diseases and Infection Control, Jena University Hospital, Erlanger Allee 101, D-07747, Jena, Germany.

ABSTRACT
The spread of carbapenem-non-susceptible Klebsiella pneumoniae strains bearing different resistance determinants is a rising problem worldwide. Especially infections with KPC (Klebsiella pneumoniae carbapenemase) - producers are associated with high mortality rates due to limited treatment options. Recent clinical studies of KPC-blood stream infections revealed that colistin-based combination therapy with a carbapenem and/or tigecycline was associated with significantly decreased mortality rates when compared to colistin monotherapy. However, it remains unclear if these observations can be transferred to K. pneumoniae harboring other mechanisms of carbapenem resistance. A three-dimensional synergy analysis was performed to evaluate the benefits of a triple combination with meropenem, tigecycline and colistin against 20 K. pneumoniae isolates harboring different β-lactamases. To examine the mechanism behind the clinically observed synergistic effect, efflux properties and outer membrane porin (Omp) genes (ompK35 and ompK36) were also analyzed. Synergism was found for colistin-based double combinations for strains exhibiting high minimal inhibition concentrations against all of the three antibiotics. Adding a third antibiotic did not result in further increased synergistic effect in these strains. Antagonism did not occur. These results support the idea that colistin-based double combinations might be sufficient and the most effective combination partner for colistin should be chosen according to its MIC.

No MeSH data available.


Related in: MedlinePlus