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Effect of antibiotics on mucoid strains of Pseudomonas aeruginosa
Abstract:
A study of the susceptibility to 18 antibiotics has been performed on 47 mucoid strains comparatively to 71 fried-egg strains of Pseudomonas aeruginosa. The minimal inhibitory concentration was determinated by agar dilution method. On the whole, the mucoid strains were more sensitive to antibiotics than the fried-egg strains. The more effective antibiotics were carbenicillins, aminosids, colistin and tetracyclines. However, this drug susceptibility of mucoid strains were heterogeneous. The results of a statistical analysis demonstrated that the strains of P. aeruginosa were distributed into two classes: a first class clustered very sensitive strains to most antibiotics and a second class clustered more resistant strains. The mucoid strains were included almost equally into the two classes (respectively 45% and 55%). The fried-egg strains were more homogeneous, since 89% of these strains were in the resistant class. The antibiotics which distinguished the best between the two classes were: tobramycin, netilmicin, amikacin, colistin and tetracyclines. A study of the phenotypes and associations of resistances has been equally performed.
Insights
Mucoid Pseudomonas aeruginosa strains showed greater antibiotic sensitivity than fried-egg strains. Statistical analysis revealed two distinct strain classes: highly sensitive and resistant, with mucoid strains distributed more evenly between them.
Area of Science:
- Microbiology
- Pharmacology
- Infectious Diseases
Background:
- Pseudomonas aeruginosa exhibits diverse phenotypes, including mucoid and fried-egg variants.
- Understanding antibiotic susceptibility differences between these phenotypes is crucial for effective treatment.
Purpose of the Study:
- To compare the antibiotic susceptibility of mucoid and fried-egg strains of Pseudomonas aeruginosa.
- To identify antibiotics that effectively differentiate between these strain types.
Main Methods:
- Agar dilution method was used to determine the minimal inhibitory concentration (MIC) for 18 antibiotics.
- Statistical analysis was employed to classify strains based on resistance patterns.
Main Results:
- Mucoid strains were generally more sensitive to antibiotics than fried-egg strains.
- Fried-egg strains predominantly fell into the resistant class (89%), while mucoid strains were more evenly distributed (45% sensitive, 55% resistant).
- Tobramycin, netilmicin, amikacin, colistin, and tetracyclines best distinguished between the two strain classes.
Conclusions:
- Phenotypic differences in Pseudomonas aeruginosa, such as mucoid versus fried-egg forms, correlate with distinct antibiotic resistance profiles.
- Targeted antibiotic selection may be necessary depending on the P. aeruginosa phenotype identified.