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[Clinical implications of the O-antigen serovar E and drug resistance in persistent Pseudomonas infection]
M Yamashita1, K Morikawa, M Kuroda
1Department of Clinical and Laboratory Science, Fukui Medical School.
Abstract:
We studied bacteriological parameters in patients with persistent Pseudomonas aeruginosa (PA) infection, including distribution of the PA O-antigen serovars, incidence of serovar conversion during treatment and relationship between these serovars and susceptibility to antibiotics. PA was identified using an automated bacterial identification system (Avantage Microbiology Center, Abbot Lab., USA) and the PA O-antigen serovar was performed with a monoclonal serovar diagnostic kit (Mei-Assay Pseudomonas Aeruginosa, Meiji Seika, Tokyo). Antibiotic susceptibility was evaluated by minimum inhibitory concentration according to the NCCLS method. The PA was isolated in 14.7% of the total of 1,900 isolates in our hospital from April, 1987 to March, 1988, and was most frequently isolated from urine specimens (51.9%), followed by sputum (40.0%). The serovar E was isolated in 57 (36.3%) of 157 PA strains tested, followed by the serovar B (21.0%) and G (17.8%). The serovar E was widely distributed in the wards of hematology (55.6%), neurosurgery (54.2%) and urology (42.3%). The serovar E showed high resistance rates to many antibiotics: 62.5% to piperacillin; 58.3%, cefsulodin; 58.3%, cefoperazone; and 70.8%, gentamicin. Serovar conversion during treatment was noticed in 8 of 24 patients with persistent PA infection. Three of 5 patients in whom the serovar had converted to the serovar E died. These results suggest that PA infection with the serovar E, especially with that converting from another serovar is an unfavorable prognostic sign.
Insights
Pseudomonas aeruginosa (PA) serovar E is frequently found in hospitals and shows high antibiotic resistance. Serovar conversion to E during treatment indicates a poor prognosis for patients with persistent PA infections.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Clinical Bacteriology
Background:
- Persistent Pseudomonas aeruginosa (PA) infections pose significant clinical challenges.
- Understanding the epidemiology and characteristics of PA serovars is crucial for effective treatment.
- Antibiotic resistance patterns associated with specific PA serovars require investigation.
Purpose of the Study:
- To investigate the distribution of PA O-antigen serovars in clinical isolates.
- To determine the incidence of serovar conversion during treatment for persistent PA infections.
- To analyze the relationship between PA serovars, antibiotic susceptibility, and patient outcomes.
Main Methods:
- Bacteriological parameters were analyzed, including PA identification using an automated system.
- PA O-antigen serovar determination was performed using a monoclonal diagnostic kit.
- Antibiotic susceptibility was evaluated via minimum inhibitory concentration (MIC) according to NCCLS guidelines.
Main Results:
- PA was isolated from 14.7% of 1,900 hospital isolates, predominantly from urine (51.9%) and sputum (40.0%).
- Serovar E was the most prevalent (36.3%), followed by serovars B (21.0%) and G (17.8%), with serovar E widespread in hematology, neurosurgery, and urology wards.
- Serovar E exhibited high resistance rates to piperacillin (62.5%), cefsulodin (58.3%), cefoperazone (58.3%), and gentamicin (70.8%).
- Serovar conversion during treatment occurred in 8 of 24 patients; 3 of 5 patients who converted to serovar E died.
Conclusions:
- Pseudomonas aeruginosa serovar E is a significant pathogen associated with high antibiotic resistance.
- Serovar conversion to E during persistent PA infection is linked to unfavorable patient outcomes.
- Targeted surveillance and treatment strategies for serovar E infections are warranted.