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Updated: Aug 9, 2025
Replication of the Ordered, Nonredundant Library of Pseudomonas aeruginosa strain PA14 Transposon Insertion Mutants
Published on: May 4, 2018
Phenotypic and genotypic characterization of clinical Pseudomonas aeruginosa
Pedduru V Mallikarjuna1, Biranthabail Dhanashree1
1Department of Microbiology, Kasturba Medical College, Mangalore, Manipal Academy of Higher Education, Manipal, India.
Objectives:
Pseudomonas aeruginosa is an opportunistic pathogen that can cause many nosocomial infections. Biofilm formation, drug resistance, and motility contribute to virulence in P. aeruginosa. This study assessed the colistin minimum inhibitory concentration (MIC), biofilm formation, presence of mod A and psl A genes, and types of motilities in multidrug-resistant (MDR) and multidrug-susceptible (MDS) P. aeruginosa.
Methods:
Sixty-two P. aeruginosa from pus and 18 from urine samples were studied for their susceptibility to commonly used antibiotics, colistin MIC by agar dilution, and biofilm-forming ability by the microtiter plate method. All MDR and MDS P. aeruginosa isolates were tested for the presence of mod A and psl A genes by PCR, and different types of motilities using specific media.
Results:
Among the 40 MDR and 40 MDS isolates, 17 each were colistin-resistant and 23 each were colistin-intermediate. Nine MDR pus isolates and three MDR urine isolates showed all three types of motilities. Thirteen MDS pus isolates and four MDS urine isolates showed both swimming and swarming motility. MDS isolates did not show twitching motility. A higher number of MDR strains were strong biofilm producers (n = 19), whereas a higher number of MDS strains (n = 24) were moderate biofilm producers (p = 0.023). Twenty-seven MDR and twenty-eight MDS isolates were positive for both mod A and pslA genes. Among the strong biofilm-forming pus isolates, a greater number of MDR isolates (n = 13 each) had modA and pslA genes compared to MDS isolates (modA p = 0.017; pslA p = 0.014).
Conclusions:
Our findings clearly showed a statistically significant association among strong biofilm formation, modA, pslA genes, and drug resistance in P. aeruginosa isolated from clinical samples. Additional studies are needed to explore other genes and factors responsible for weak and moderate biofilm formation and drug resistance.
Insights
Multidrug-resistant Pseudomonas aeruginosa strains show stronger biofilm formation linked to modA and pslA genes. This association highlights key factors in virulence and drug resistance in clinical isolates.
Area of Science:
- Clinical Microbiology
- Bacterial Pathogenesis
- Molecular Biology
Background:
- Pseudomonas aeruginosa is an opportunistic pathogen causing significant nosocomial infections.
- Biofilm formation, drug resistance, and motility are critical virulence factors in P. aeruginosa.
- Understanding the genetic basis of these traits is crucial for combating P. aeruginosa infections.
Purpose of the Study:
- To assess colistin minimum inhibitory concentration (MIC), biofilm formation, and the presence of modA and pslA genes.
- To compare these characteristics between multidrug-resistant (MDR) and multidrug-susceptible (MDS) P. aeruginosa isolates.
- To investigate the types of motility in MDR and MDS P. aeruginosa.
Main Methods:
- Analyzed 62 P. aeruginosa from pus and 18 from urine samples.
- Determined antibiotic susceptibility, colistin MIC, and biofilm-forming ability.
- Utilized PCR for modA and pslA gene detection and specific media for motility assays.
Main Results:
- A significant association was found between strong biofilm formation, modA and pslA genes, and drug resistance in P. aeruginosa.
- MDR strains showed a higher prevalence of strong biofilm production compared to MDS strains.
- Both MDR and MDS isolates carried modA and pslA genes, with higher numbers in strong biofilm-forming MDR isolates.
Conclusions:
- Strong biofilm formation, modA, and pslA genes are significantly associated with drug resistance in clinical P. aeruginosa isolates.
- These findings provide insights into the virulence mechanisms of P. aeruginosa.
- Further research is needed to identify other genes and factors contributing to biofilm formation and drug resistance.
