minocycline and endolysin

MRSA is the predominant pathogen responsible for fatal burn wound infection in patients. Antibiotic resistance and its ability to form biofilms on the surface of burn wounds limit the use of antibiotics to contain this pathogen. The results of present study have shown that single dose of combination therapy of endolysin MR-10 (50μg/s.c) and minocycline (50mg/kg/orally) resulted in 100% survival of group of mice with systemic MRSA infection. Maximum reduction in bacterial load in various organs was observed in the group that received combination therapy. In comparison to control, a significant reduction (p<0.01) of 4.82, 1.81, 1.51, 1.2 logs was observed in skin, blood, liver and spleen respectively, by 3rd day post infection. As a result of which, all organs became sterile thereby protecting mice from mortality. Histopathological analysis corroborated our findings showing no signs of inflammation and bacterial infection in the group that received combination therapy. Treatment of localized burn wound infection with combination therapy resulted in early resolution of infection followed by fast healing. The group that received combination therapy showed complete resolution of infection in less than 10days. Moreover, the skin samples obtained from animals treated with combination therapy showed no myeloperoxidase (MPO) activity on 10th day post treatment. In combination therapy group, ∼98% wound contraction was observed by 12th day followed by complete closure of wound within ∼14days. The histopathological analysis showed no signs of inflammation and infection. Collagen staining revealed early signs of re-epithelization of epidermis and signs of collagen regeneration in-group that received combination therapy. Hence, this study suggests that the combined therapy of endolysin MR-10 and minocycline is a better option in controlling burn wound infections.

Topics: Administration, Oral; Animal Structures; Animals; Anti-Bacterial Agents; Bacterial Load; Burns; Disease Models, Animal; Drug Therapy, Combination; Endopeptidases; Female; Histocytochemistry; Injections, Subcutaneous; Methicillin-Resistant Staphylococcus aureus; Mice, Inbred BALB C; Minocycline; Sepsis; Staphylococcal Infections; Survival Analysis; Time Factors; Treatment Outcome; Wound Infection

Lysins are novel class of anti-infectives which are derived from bacteriophage. In the present study, the potential of previously characterised phage borne endolysin MR-10 in eradicating methicillin-resistant Staphylococcus aureus (MRSA) biofilm was evaluated. Scanning electron microscopic examination showed that both ica-positive and ica-negative MRSA formed equally potent mature biofilm. Different approaches were employed to eradicate the young as well as older biofilm formed by both types of MRSA strains. Our results showed a significant decrease (p < 0.01) in biofilm count on sequentially treating the MRSA biofilm with minocycline (4 μg/ml) for 3 h followed by treatment with endolysin MR-10. Since endolysin can act effectively irrespective of the metabolic status of the cells hence, they are capable of killing the rapidly growing cells (log phase cells) as well as non-dividing (stationary phase) cells. As a result they are effective in eradicating the younger and older biofilm. On staining the ica-positive MRSA biofilm with wheat germ agglutinin (WGA)-Alexa Flour 350, reduction in poly-intercellular adhesion (PIA) content was observed in comparison to control biofilm. In addition, a significant decrease (p < 0.01) in extracellular DNA (eDNA) content of ica-negative MRSA biofilm was also observed. Further, Live/Dead Baclight™ staining also showed presence of higher population of dead cells after treatment with minocycline and endolysin MR-10. Hence, our results showed that using minocycline sequentially with endolysin, MR-10 can effectively eradicate both young as well as older biofilm formed by ica-positive and ica-negative MRSA.

Topics: Adhesins, Bacterial; Anti-Bacterial Agents; Bacteriophages; Biofilms; Endopeptidases; Methicillin-Resistant Staphylococcus aureus; Minocycline