Effect of Nanosulfur Against Multidrug-Resistant Staphylococcus pseudintermedius and Pseudomonas aeruginosa

Multidrug resistance (MDR) has significantly increased in the past decades and the use of nanotechnology has opened new venues for novel treatments. Nanosulfur is a potent antimicrobial agent and a cheaper alternative to other nanomaterials. However, very few studies have been published on its activity against MDR organisms. Therefore, the goal of this in vitro study was to assess cytotoxicity, antimicrobial, and anti-biofilm activity of nanosulfur (47 nm, orthorhombic) against clinical isolates of MDR Staphylococcus pseudintermedius (SP) and Pseudomonas aeruginosa (PA) in planktonic and biofilm state using canine skin explants. Nanosilver (50 nm, spherical) was tested as a comparative control. Concentrations between 1866.7 and 0.11 mu g/mL of both nanoparticles were tested. The ultrastructure of nanosulfur was assessed via electron microscopy. Both types of nanoparticles showed no direct cytotoxicity on a canine keratinocyte cell line. In the planktonic phase, nanosulfur was able to inhibit or kill (6-log(10) reduction of CFU) 7 of 10 MDR-SP isolates at 233.3 mu g/mL, whereas, when in hiofilm state, 6 of 10 isolates were killed at different concentrations (233.33 to 1866.7 mu g/mL). Nanosilver did not show any antimicrobial or anti-biofilm activity at any concentrations tested. Both types of nanoparticles were ineffective against MDR-PA in either state. Ultrastructurally, nanosulfur was present in individual nanoparticles as well as forming larger nanoclusters. This is the first study showing an antimicrobial and anti-biofilm activity of nanosulfur for MDR-SP in absence of cytotoxicity. Nanosulfur has the potential to be used in veterinary and human medicine as effective, safe, and cheap alternative to antimicrobials and anti-biofilm agents currently available.

Automated summary

Nanosulfur exhibits antimicrobial and anti-biofilm activity against multidrug-resistant Staphylococcus pseudintermedius, while being ineffective against multidrug-resistant Pseudomonas aeruginosa. Nanosulfur has the potential to be used as an alternative to antimicrobials and anti-biofilm agents in veterinary and human medicine.