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[Comparative activity of ticarcillin-clavulanic acid and various beta-lactams against Pseudomonas maltophilia]
1Institut de Bactériologie, Faculté de Médecine, Université Louis Pasteur, Strasbourg.
Abstract:
An increase is observed in the isolation of P. maltophilia as a casual agent of nosocomial infection, particularly in hospitalized immunocompromised patients. These infections are associated with the acute problem of their treatment as most of the P. maltophilia strains are generally resistant to many of the commonly used antimicrobial agents, including those active against Pseudomonas aeruginosa: beta lactams, aminoglycosides and imipenem. This resistance is correlated with two inducible beta lactamases (L1, pI = 6.9; L2, pI = 8.4). Azlocillin, piperacillin, cefoperazone, ceftazidime, latamoxef, ticarcillin, ticarcillin and clavulanic acid in combination were tested against 93 P. maltophilia isolates by disk diffusion testing and agar dilution technique. The association of clavulanic acid with ticarcillin resulted in better MIC values for ticarcillin (MIC 50 = 32, MIC 90 = 128). 96% of strains were sensible to the breakpoint of 128 mg/l. Other beta lactam antibiotics showed a loss of activity except for latamoxef (67% of strains susceptible to 4 mg/l) which is a potent inhibitor of both beta-lactamases. According to these results, the combination of clavulanic acid with ticarcillin may be useful in the treatment of P. maltophilia acquired hospital infections.
Insights
The study found that combining ticarcillin with clavulanic acid effectively treated hospital-acquired infections caused by drug-resistant Pseudomonas maltophilia. This combination shows promise for managing these difficult-to-treat infections.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Antimicrobial Resistance
Background:
- Pseudomonas maltophilia is an increasing cause of hospital-acquired infections, especially in immunocompromised patients.
- Most P. maltophilia strains exhibit resistance to common antibiotics, complicating treatment.
- Antibiotic resistance in P. maltophilia is linked to inducible beta-lactamases (L1 and L2).
Purpose of the Study:
- To evaluate the efficacy of various beta-lactam antibiotics, alone and in combination with clavulanic acid, against P. maltophilia isolates.
- To determine the minimum inhibitory concentrations (MICs) of tested antibiotics and combinations.
- To identify potential treatment options for P. maltophilia nosocomial infections.
Main Methods:
- Disk diffusion testing and agar dilution techniques were used.
- Ninety-three clinical isolates of P. maltophilia were tested.
- Susceptibility testing included azlocillin, piperacillin, cefoperazone, ceftazidime, latamoxef, and ticarcillin/clavulanic acid.
Main Results:
- Ticarcillin combined with clavulanic acid demonstrated improved MIC values (MIC50 = 32, MIC90 = 128), with 96% of strains susceptible to 128 mg/l.
- Latamoxef showed activity, with 67% of strains susceptible to 4 mg/l, indicating it is a potent beta-lactamase inhibitor.
- Other beta-lactam antibiotics exhibited reduced activity against the tested P. maltophilia strains.
Conclusions:
- The combination of ticarcillin and clavulanic acid shows significant potential for treating P. maltophilia hospital-acquired infections.
- Latamoxef is a viable option due to its potent beta-lactamase inhibition and activity against susceptible strains.
- Further investigation into these combinations is warranted for effective management of P. maltophilia infections.