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[Loss of antibiotic sensitivity of Pseudomonas aeruginosa strains during treatment]
M L López-Yeste1, J Chaves, J Garau
1Servicio de Microbiología, Hospital Mútua de Terrassa, Barcelona.
Background:
Loss of sensitivity to betalactamic, quinolones and aminoglucoside antibiotics has been described during treatment of infections produced by strains of Pseudomonas aeruginosa. Sixteen nosocomial strains isolated over a year during which sensitivity to one or several antibiotics of the above mentioned groups had been lost during the course of treatment were studied.
Methods:
The strains were identified by conventional techniques. Sensitivity to antibiotics was studied by determination of the minimum inhibitory concentration in solid medium, according to the guidelines of the National Committee for Clinical Laboratory Standards. Plasmidic beta-lactamases were identified by analytic isoelectric focusing. Hyperproduction of chromosomic lactamase was studied by a qualitative technique. The 0 antigens were studied against rabbit antisera. The pyocinetype was determined according to the Fyfe method. Plasmids were detected by alkaline lysis extraction and electrophoresis in agarose gel.
Results:
The 16 strains in which changes in sensitivity were observed during the course of treatment represent 4.47% of all P. aeruginosa isolates during one year. Loss of sensitivity to betalactamic antibiotics was observed in 10 strains, in one to aminoglucosides, in two to ciprofloxacin, simultaneously to aminoglucosides and ciprofloxacin in one and to betalactamic and ciprofloxacin in another two. Six of the 13 patients (46%) required a change in antibiotic treatment.
Conclusions:
The convenience of following the sensitivity of the strains of Pseudomonas aeruginosa isolated in a patients is suggested to thereby avoid therapeutic failure and the potential danger of clonal dissemination of the strains which have lost sensitivity.
Insights
Antibiotic resistance in Pseudomonas aeruginosa strains can emerge during treatment, leading to therapeutic failure. Monitoring bacterial sensitivity is crucial to prevent the spread of resistant strains and ensure effective patient care.
Area of Science:
- Clinical microbiology
- Infectious diseases
- Antimicrobial resistance
Background:
- Pseudomonas aeruginosa infections are a concern in nosocomial settings.
- Loss of antibiotic sensitivity during treatment has been observed.
- This study focused on 16 nosocomial P. aeruginosa strains exhibiting reduced sensitivity.
Purpose of the Study:
- To investigate the phenomenon of acquired antibiotic resistance in Pseudomonas aeruginosa during patient treatment.
- To identify the patterns of resistance development against key antibiotic classes.
- To assess the clinical implications of this resistance.
Main Methods:
- Strain identification using conventional microbiological techniques.
- Antibiotic sensitivity testing via determination of minimum inhibitory concentration (MIC).
- Characterization of beta-lactamases, O antigens, pyocinetype, and plasmid analysis.
Main Results:
- Acquired resistance was observed in 4.47% of P. aeruginosa isolates over one year.
- Resistance primarily affected beta-lactam and quinolone antibiotics.
- Nearly half of patients (46%) required a change in antibiotic therapy due to resistance.
Conclusions:
- Continuous monitoring of P. aeruginosa sensitivity is recommended to prevent treatment failures.
- Early detection of resistance can mitigate the risk of clonal dissemination.
- Proactive management strategies are essential for combating antimicrobial resistance.