β-Lactam antibiotics and vancomycin inhibit the growth of planktonic and biofilm Candida spp.: an additional benefit of antibiotic-lock therapy?

The aim of this study was to evaluate the effects of cefepime, meropenem, piperacillin/tazobactam (TZP) and vancomycin on strains of Candida albicans and Candida tropicalis in planktonic and biofilm forms. Twenty azole-derivative-resistant strains of C. albicans (n=10) and C. tropicalis (n=10) were tested. The susceptibility of planktonic Candida spp. to the antibacterial agents was investigated by broth microdilution. The XTT reduction assay was performed to evaluate the viability of growing and mature biofilms following exposure to these drugs. Minimum inhibitory concentrations (MICs) ranged from 0.5 mg/mL to 2 mg/mL for cefepime, TZP and vancomycin and from 0.5 mg/mL to 1 mg/mL for meropenem and the drugs also caused statistically significant reductions in biofilm cellular activity both in growing and mature biofilm. Since all of the tested drugs are commonly used in patients with hospital-acquired infections and in those with catheter-related infections under antibiotic-lock therapy, it may be possible to obtain an additional benefit from antibiotic-lock therapy with these drugs, namely the control of Candida biofilm formation.