Comparative Efficacy of an Engineered Cationic Peptide against E. fecalis

OBJECTIVE: Engineered cationic peptides (eCAPS) have been reported to have significant antibacterial activity, particularly against the Gram positive isolates. Here, we wanted to study eCAP activity against clinically isolated vancomycin susceptible and resistant E. faecalis from necrotic root canals and substantiate its reported rapid activity (minutes).

METHODS: A macrotiter method was used to detect rapid efficacy of the eCAP. Variables included: 1) vancomycin resistance of E. fecalis, 2) time of activity (2 min-24 hrs) and 3) molarity of eCAP at four concentrations: 0.25, 0.5, 1.0 and 3.0 uM. Calculations were based on best fit curve for: 1) linear regression using Y = MX + B, 2) polynomial regression using Y = MX2 + MX + B, 3) log reduction and 4) area graph of log reduction.

RESULTS: The eCAP evaluated showed noticeable (~80%) killing activity in the first two minutes with a corresponding log reduction of 0.36 at 1 uM and 1.45 at 3 uM. Significant killing (greater than 90%) was achieved at four minutes with corresponding log reduction of 1.3 at 1 uM and 2.51 at 3 uM. Greater than 95% killing for both vancomycin susceptible and resistant E. fecalis occurred in six to eight minutes. Linear and polynominal regression highlighted greatest log reduction for VRE, with the lowest concentration of 0.025 uM maintaining effective activity for either strain.

CONCLUSION: eCAP had remarkable, rapid, activity independent of vancomycin resistance, being superior to the traditional endodontic irrigants based on published data for rapidity in % killing and log reduction.