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In vitro bactericidal activities of gentamicin, cefazolin, and imipenem in peritoneal dialysis fluids
D C Halstead1, J Guzzo, J A Giardina
1Department of Microbiology, HealthEast Laboratories, Allentown Hospital-Lehigh Valley Hospital Center, Pennsylvania 18105.
Abstract:
Continuous ambulatory peritoneal dialysis is an important modality of therapy for patients with renal disease. However, peritonitis continues to be a major risk factor and is usually treated by intraperitoneal administration of antimicrobial agents. Few data are available concerning the stability of antimicrobial agents in peritoneal dialysis solution beyond 48 h. Our investigation was designed to establish the chemical and biological stability of gentamicin alone and in combination with cefazolin in peritoneal dialysis solution at 6 and 72 h by an immunoassay and by an in vitro bactericidal test against American Type Culture Collection (Rockville, Md.) strains of Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus epidermidis. In addition, uninfected peritoneal dialysis effluent was inoculated with three American Type Culture Collection strains and gentamicin or imipenem. Gentamicin alone or in combination with cefazolin was not altered chemically and was bactericidal for Staphylococcus spp. but not P. aeruginosa. In contrast, imipenem was active against both Staphylococcus spp. and P. aeruginosa. Undefined factors other than inactivation of gentamicin may be responsible for the lack of bactericidal activity and treatment failure of Pseudomonas infections.
Insights
Gentamicin and cefazolin in peritoneal dialysis solution remain stable but are not fully effective against Pseudomonas aeruginosa. Further research is needed to understand treatment failures in peritonitis caused by this pathogen.
Area of Science:
- Nephrology
- Infectious Diseases
- Pharmacology
Background:
- Continuous ambulatory peritoneal dialysis (CAPD) is a vital renal replacement therapy.
- Peritonitis is a significant complication of CAPD, often treated with intraperitoneal antibiotics.
- Limited data exist on the long-term stability and efficacy of antibiotics in dialysis solutions.
Purpose of the Study:
- To assess the chemical and biological stability of gentamicin and cefazolin in peritoneal dialysis solution.
- To evaluate the in vitro bactericidal activity of these agents against common peritonitis-causing bacteria.
- To investigate potential reasons for treatment failures in Pseudomonas aeruginosa peritonitis.
Main Methods:
- Chemical stability assessed by immunoassay at 6 and 72 hours.
- Biological stability evaluated using in vitro bactericidal tests.
- Tested against Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus epidermidis strains.
Main Results:
- Gentamicin and cefazolin showed chemical stability in peritoneal dialysis solution up to 72 hours.
- These antibiotics were bactericidal against Staphylococcus species but not Pseudomonas aeruginosa.
- Imipenem demonstrated activity against both Staphylococcus species and Pseudomonas aeruginosa.
Conclusions:
- Gentamicin and cefazolin are chemically stable in peritoneal dialysis solution but lack consistent bactericidal activity against Pseudomonas aeruginosa.
- Factors beyond antibiotic inactivation may contribute to treatment failures in Pseudomonas peritonitis.
- Alternative or adjunctive therapies may be necessary for effective management of Pseudomonas peritonitis in CAPD patients.