In vitro bactericidal activities of gentamicin, cefazolin, and imipenem in peritoneal dialysis fluids

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.

Influence of carbon dioxide on growth and antibiotic susceptibility of coagulase-negative staphylococci cultured in human peritoneal dialysate

“…It is well known that isolates from CAPD patients with peritonitis often grow poorly or not at all in the fresh acidic dialysis fluid that is instilled into the peritoneal cavity (11,14). Furthermore, the composition of this fluid changes rapidly during dialysis, and so many workers have instead used PUD as a culture medium (8)(9)(10)(11)(12)(13)(14)16). The pH of PUD quoted in these references ranged from 7.0 to 8.6.…”

“…The pH of PUD quoted in these references ranged from 7.0 to 8.6. In addition, some workers have centrifuged, filtered, or acidified the fluid prior to use (9)(10)(11)(12)14). In no case was it reported that increased levels of carbon dioxide were used during culture.…”

“…Significantly different conditions have been employed in the study of microbial growth and antibiotic activity in PUD (8)(9)(10)(11)(12)(13)(14)16). It is clear that a comparison of studies using such different approaches cannot be easily made.…”

“…fluid represents a step closer to these conditions. The peritoneal cavities of patients undergoing continuous ambulatory peritoneal dialysis (CAPD) represent a unique growth environment for potential pathogens, and therefore in vitro studies of peritonitis-causing isolates have employed used peritoneal dialysis fluid (PUD) as a culture medium (8)(9)(10)(11)(12)(13)(14)16). In addition to differences in growth kinetics, we have shown unique phenotypic changes in staphylococcal cell surface characteristics associated with growth in PUD (17,19; S. P. Denyer, M. C. Davies, J.…”

Peritoneal Fluid Titer Test for Peritoneal Dialysis-Related Peritonitis

“…Finally, there is evidence in vitro that antibiotic activity is different in dianeal fluid than in standard broth. Significant impairment in the activities of aminoglycosides, fluoroquinolones, cephalosporins, and vancomycin has been shown in the comparison of MICs and minimum bactericidal concentrations in dianeal fluid to standard broth (12,28,30,31,33).…”