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Outer membrane alterations in Pseudomonas aeruginosa after five-day exposure to quinolones and carbapenems
P Cipriani1, A Giordano, A Magni
1Department of Clinical Microbiology I, Faculty of Medicine and Surgery, La Sapienza University of Rome, Italy.
Abstract:
A Pseudomonas aeruginosa strain (P.aeruginosa), recently isolated in clinical practice, was tested to evaluate the changes induced in the minimal inhibitory concentration (MIC) values and in the outer membrane (OM) components by a five-day exposure to sub-MIC concentrations of the quinolones ciprofloxacin and PD-131.628 and the carbapenems imipenem and meropenem. The treated strain showed a thirty two-fold increase in MIC values for quinolones and a sixteen-fold increase for carbapenems. The electrophoretic profile of the OM proteins of the strain treated with quinolones showed that ciprofloxacin induces loss of the 47 Kd protein band, whereas PD-131.628 modifies the protein pattern of the strain only after five days of exposure. The carbapenems engendered disappearance of the same protein band. Qualitative lipopolysaccaride (LPS) analysis did not reveal any change after antibiotic treatment of the strain, whereas the 2-keto-3-deoxyoctonic acid (KDO) assay showed considerable reduction in the strain treated with sub-MIC doses of meropenem. It can therefore be safely stated that the D2 protein plays an important though not exclusive role in enhancing strain resistance against the two classes of antibiotics tested in our study.
Insights
This study shows that exposing Pseudomonas aeruginosa to low antibiotic doses significantly increases its resistance to quinolones and carbapenems. A specific outer membrane protein (D2) appears crucial for this enhanced bacterial resistance.
Area of Science:
- Microbiology
- Bacterial Resistance
- Drug Discovery
Background:
- Pseudomonas aeruginosa is a significant opportunistic pathogen.
- Antibiotic resistance in P. aeruginosa is a growing clinical concern.
- Outer membrane proteins play a role in bacterial antibiotic resistance.
Purpose of the Study:
- To investigate the effects of sub-inhibitory concentrations of quinolones and carbapenems on P. aeruginosa.
- To analyze changes in minimal inhibitory concentration (MIC) values and outer membrane (OM) components.
- To identify potential mechanisms of antibiotic resistance in P. aeruginosa.
Main Methods:
- Exposure of P. aeruginosa to sub-MIC concentrations of ciprofloxacin, PD-131.628, imipenem, and meropenem for five days.
- Determination of MIC values for quinolones and carbapenems.
- Analysis of OM protein profiles using electrophoresis.
- Qualitative lipopolysaccharide (LPS) analysis and 2-keto-3-deoxyoctonic acid (KDO) assay.
Main Results:
- A 32-fold increase in MIC values for quinolones and a 16-fold increase for carbapenems was observed.
- Ciprofloxacin treatment led to the loss of a 47 kDa OM protein band; carbapenems caused the disappearance of the same band.
- PD-131.628 modified the OM protein pattern after five days.
- LPS analysis showed no changes, but meropenem treatment significantly reduced KDO levels.
Conclusions:
- The D2 protein plays a significant role in P. aeruginosa resistance to quinolones and carbapenems.
- Sub-MIC antibiotic exposure can induce rapid resistance mechanisms in P. aeruginosa.
- Understanding these resistance mechanisms is vital for developing new antimicrobial strategies.