Antimicrobial activity of oritavancin and comparator agents when tested against Gram-positive bacterial isolates causing infections in cancer patients (2014-16)

Comparative In Vitro Activity of New Lipoglycopeptides and Vancomycin Against Ocular Staphylococci and Their Toxicity on the Human Corneal Epithelium

PURPOSE

The purpose of this study was to assess the potential of new lipoglycopeptides as novel topical therapies for improved treatment of recalcitrant ocular infections. We evaluated the in vitro antimicrobial activity of oritavancin, dalbavancin, and telavancin compared with vancomycin (VAN) against a large collection of ocular staphylococcal isolates and their cytotoxicity on human corneal epithelial cells (HCECs).

METHODS

Antimicrobial susceptibility testing was performed by broth microdilution against 223 Staphylococcus spp. clinical isolates. Time-kill kinetics were determined for methicillin-resistant strains of Staphylococcus aureus (MRSA) (n = 2) and Staphylococcus epidermidis (MRSE) (n = 1). In vitro cytotoxicity assays were performed with AlamarBlue and live/dead staining on HCECs.

RESULTS

All new lipoglycopeptides showed strong in vitro potency against ocular staphylococci, including multidrug-resistant MRSA strains, with dalbavancin showing a slightly higher potency overall [minimum inhibitory concentration (MIC) 90 0.06 μg/mL] compared with telavancin and oritavancin (MIC 90 0.12 μg/mL), whereas VAN had the lowest potency (MIC 90 2 μg/mL). Oritavancin exerted rapid bactericidal activity within 1 h for MRSA and 2 h for MRSE. All other drugs were bactericidal within 24 h. At a concentration commonly used for topical preparations (25 mg/mL), cytotoxicity was observed for VAN after 5 min of incubation, whereas reduction in HCEC viability was not seen for telavancin and was less affected by oritavancin and dalbavancin. Cytotoxicity at 25 mg/mL was seen for all drugs at 30 and 60 min but was significantly reduced or undetected for lower concentrations.

CONCLUSIONS

Our study demonstrates that new lipoglycopeptides have substantially better in vitro antimicrobial activity against ocular staphylococcal isolates compared with VAN, with a similar or improved toxicity profile on HCECs.

Antimicrobial resistance in nephrology

The prevalence of antimicrobial resistance among many common bacterial pathogens is increasing. The emergence and global dissemination of these antibiotic-resistant bacteria (ARB) is fuelled by antibiotic selection pressure, inter-organism transmission of resistance determinants, suboptimal infection prevention practices and increasing ease and frequency of international travel, among other factors. Patients with chronic kidney disease, particularly those with end-stage renal disease who require dialysis and/or kidney transplantation, have some of the highest rates of colonization and infection with ARB worldwide. These ARB include methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus spp. and several multidrug-resistant Gram-negative organisms. Antimicrobial resistance limits treatment options and increases the risk of infection-related morbidity and mortality. Several new antibiotic agents with activity against some of the most common ARB have been developed, but resistance to these agents is already emerging and highlights the dire need for new treatment options as well as consistent implementation and improvement of basic infection prevention practices. Clinicians involved in the care of patients with renal disease must be familiar with the local epidemiology of ARB, remain vigilant for the emergence of novel resistance patterns and adhere strictly to practices proven to prevent transmission of ARB and other pathogens.