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[Comparative activity of azlocillin on Pseudomonas species excluding Pseudomonas aeruginosa]
Abstract:
The minimal inhibitory concentrations (MIC) of three acylureidopenicillins (azlocillin, mezlocillin, piperacillin) and three third generation cephalosporins (cefotaxime, cefoperazone, cefsulodin) against 249 randomized strains of Pseudomonas spp. representing 10 species other than Pseudomonas aeruginosa, were determined by the agar dilution method in Mueller-Hinton agar and compared by parametric statistical tests. Fresh clinical and environmental hospital isolates belonged to the following species: P. fluorescens (35), P. putida (37), P. stutzeri (17), P. mendocina (4), P. cepacia (37), P. pickettii (22), P. acidovorans (36), P. diminuta (5), P. paucimobilis (23), P. maltophilia (37). Azlocillin inhibited over 88% of Pseudomonas spp at 64 mg/l or less. This good antipseudomonal activity in vitro was comparable to those of piperacillin and cefotaxime with a minimal inhibitory concentrations 50 value of 8 mg/l. Against these Pseudomonas spp, the ranking order of activity was azlocillin = piperacillin = cefotaxime greater than cefoperazone greater than mezlocillin greater than cefsulodin. Like piperacillin or cefotaxime, azlocillin, was effective against ticarcillin--and aminoglycoside--resistant Pseudomonas spp. Against P. maltophilia and P. cepacia, the two Pseudomonas spp other than P. aeruginosa that are important pathogens in opportunistic infections and in their vast majority are resistant to amino glycosides, azlocillin was significantly active. Only in the case of P. maltophilia, cefoperazone had a lower minimal inhibitory concentrations 50 (8 mg/l vs. 32 mg/l).
Insights
Azlocillin demonstrated strong in vitro activity against various Pseudomonas species, comparable to piperacillin and cefotaxime. This antibiotic was effective against resistant strains, including opportunistic pathogens like Pseudomonas maltophilia and Pseudomonas cepacia.
Area of Science:
- Microbiology
- Infectious Diseases
- Pharmacology
Background:
- Pseudomonas species, excluding Pseudomonas aeruginosa, are significant in hospital-acquired infections.
- Many of these non-aeruginosa Pseudomonas strains exhibit resistance to common antibiotics like ticarcillin and aminoglycosides.
- Understanding the in vitro susceptibility patterns of these pathogens is crucial for effective treatment strategies.
Purpose of the Study:
- To determine the in vitro antimicrobial activity of acylureidopenicillins and third-generation cephalosporins against a diverse collection of non-aeruginosa Pseudomonas species.
- To compare the efficacy of azlocillin, mezlocillin, piperacillin, cefotaxime, cefoperazone, and cefsulodin against these clinically relevant Pseudomonas isolates.
- To evaluate the activity of azlocillin against antibiotic-resistant strains, particularly opportunistic pathogens like P. maltophilia and P. cepacia.
Main Methods:
- Agar dilution method using Mueller-Hinton agar was employed to determine minimal inhibitory concentrations (MIC).
- A total of 249 randomized clinical and environmental isolates from 10 different non-aeruginosa Pseudomonas species were tested.
- Parametric statistical tests were used to compare the antimicrobial activities of the tested agents.
Main Results:
- Azlocillin inhibited over 88% of tested Pseudomonas spp. at MICs of 64 mg/l or less, showing potent antipseudomonal activity.
- The ranking order of in vitro activity was azlocillin = piperacillin = cefotaxime > cefoperazone > mezlocillin > cefsulodin.
- Azlocillin demonstrated significant activity against ticarcillin- and aminoglycoside-resistant Pseudomonas spp., including P. maltophilia and P. cepacia.
Conclusions:
- Azlocillin exhibits excellent in vitro activity against a broad range of non-aeruginosa Pseudomonas species, making it a valuable therapeutic option.
- Its efficacy against antibiotic-resistant strains, including important opportunistic pathogens, highlights its clinical relevance.
- Azlocillin, piperacillin, and cefotaxime represent the most active agents tested against the studied Pseudomonas species.