Laboratory studies on coagulase-negative staphylococci from CAPD-associated peritonitis

Area of Science:

• Microbiology
• Infectious Diseases
• Pharmacology

Background:

• Coagulase-negative staphylococci are a common cause of peritonitis in patients undergoing continuous ambulatory peritoneal dialysis (CAPD).
• Understanding antibiotic activity in both broth and used dialysate is crucial for effective treatment of CAPD-associated peritonitis.

Purpose of the Study:

• To compare the static and kinetic activities of selected antibiotics against coagulase-negative staphylococci isolated from CAPD patients.
• To assess antibiotic efficacy in both standard broth and used dialysate environments.

Main Methods:

• Antibiotic susceptibility testing (static and kinetic) was performed on 23 strains of coagulase-negative staphylococci.
• Tests were conducted in both sterile broth and used peritoneal dialysis fluid.
• Bacterial isolates were characterized by biotyping and phage typing.

Main Results:

• Vancomycin demonstrated effectiveness against all isolates, comparable to flucloxacillin and cefuroxime, though some cefuroxime resistance was noted.
• Gentamicin was rapidly bactericidal against 60% of sensitive strains.
• Fusidic acid showed limited bactericidal activity and significant resistance, while rifampicin led to the emergence of resistance.
• Combination therapies (clavulanic acid/amoxycillin, sulbactam/ampicillin) exhibited good static activity.
• Staphylococcus epidermidis biotype SII was predominant, but no correlation between biotype and antibiotic resistance was found.

Conclusions:

• Vancomycin, flucloxacillin, and cefuroxime are effective options for treating CAPD peritonitis caused by coagulase-negative staphylococci.
• Gentamicin is a viable option for susceptible strains.
• Fusidic acid and rifampicin present challenges due to resistance and emergence of resistance, respectively.
• Antibiotic choice should consider both static and kinetic activity in the peritoneal dialysis environment.