Combating the melioidosis pathogen using antibiotics in combination with silver nanoparticles
Melioidosis is an infectious disease caused by the Gram-negative bacillus bacterium, Burkholderia pseudomallei. Due to the emerging resistance of B. pseudomallei to antibiotics, including ceftazidime (CAZ), the development of novel antibiotics and alternative modes of treatment has become an urgent issue. Here, we demonstrate an ability to synergistically increase the efficiency of antibiotics through their combination with silver nanoparticles (AgNPs).
Combinations of four conventional antibiotics, including CAZ, imipenem (IMI), meropenem (MER), or gentamicin sulfate (GENT), with AgNPs were tested for their bactericidal effects against three isolates of B. pseudomallei, including 1026b, H777, and 316c, using the microdilution checkerboard method of antibiotic and AgNPs mixing. Morphological changes in the bacteria after treatment with the combined antibiotic-AgNPs was observed using scanning electron microscopy (SEM).
The combination of four antibiotics with AgNPs gave fractional inhibitory concentration (FIC) index values and fractional bactericidal concentration (FBC) index values ranging from 0.312 to 0.75 µg/mL and 0.252 to 0.625 µg/mL, respectively, against the three isolates of B. pseudomallei. SEM imaging revealed damage to the bacterial cell structure at the minimal inhibitory concentration (MIC) and FIC levels, while extreme severe cellular damage was observed at the FBC level. Surprisingly, at the FBC level, the bacteria produced large amounts of fibers that are the components of biofilm.
The study clearly shows that most of the combinatorial treatments exhibited synergistic antimicrobial effects against all three isolates of B. pseudomallei. The highest enhancing effect was observed for GENT with AgNPs. We also found that the combination of these antibiotics with AgNPs restored their bactericidal potency in the bacterial strains previously shown to be resistant to the antibiotic. The observed synergistic activities of conventional antibiotics with AgNPs suggest that it might also be possible to achieve equivalent or higher levels of bacterial cell death with lower concentrations of antibiotics using the combined treatments. These results support the use of the antibiotic/AgNPs combination as an alternative design strategy for new therapeutics to more effectively combat melioidosis.
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Posted 28 May, 2020
Combating the melioidosis pathogen using antibiotics in combination with silver nanoparticles
Posted 28 May, 2020
Melioidosis is an infectious disease caused by the Gram-negative bacillus bacterium, Burkholderia pseudomallei. Due to the emerging resistance of B. pseudomallei to antibiotics, including ceftazidime (CAZ), the development of novel antibiotics and alternative modes of treatment has become an urgent issue. Here, we demonstrate an ability to synergistically increase the efficiency of antibiotics through their combination with silver nanoparticles (AgNPs).
Combinations of four conventional antibiotics, including CAZ, imipenem (IMI), meropenem (MER), or gentamicin sulfate (GENT), with AgNPs were tested for their bactericidal effects against three isolates of B. pseudomallei, including 1026b, H777, and 316c, using the microdilution checkerboard method of antibiotic and AgNPs mixing. Morphological changes in the bacteria after treatment with the combined antibiotic-AgNPs was observed using scanning electron microscopy (SEM).
The combination of four antibiotics with AgNPs gave fractional inhibitory concentration (FIC) index values and fractional bactericidal concentration (FBC) index values ranging from 0.312 to 0.75 µg/mL and 0.252 to 0.625 µg/mL, respectively, against the three isolates of B. pseudomallei. SEM imaging revealed damage to the bacterial cell structure at the minimal inhibitory concentration (MIC) and FIC levels, while extreme severe cellular damage was observed at the FBC level. Surprisingly, at the FBC level, the bacteria produced large amounts of fibers that are the components of biofilm.
The study clearly shows that most of the combinatorial treatments exhibited synergistic antimicrobial effects against all three isolates of B. pseudomallei. The highest enhancing effect was observed for GENT with AgNPs. We also found that the combination of these antibiotics with AgNPs restored their bactericidal potency in the bacterial strains previously shown to be resistant to the antibiotic. The observed synergistic activities of conventional antibiotics with AgNPs suggest that it might also be possible to achieve equivalent or higher levels of bacterial cell death with lower concentrations of antibiotics using the combined treatments. These results support the use of the antibiotic/AgNPs combination as an alternative design strategy for new therapeutics to more effectively combat melioidosis.
Figure 1
Figure 2
Figure 3