Abstract Staphylococcus aureus and Staphylococcus epidermidis have microbial surface components recognizing adhesive matrix molecules (MSCRAMM) adhesion proteins that enhance their biofilm formation ability, as well as virulence factors that influence morbidity and mortality in hospital settings. In this work, four peptides analogous of the peptide LL-37 that were evaluated to inhibit biofilm formation and its action potential on the expression of MSCRAMM proteins in clinical isolates through different tests, such as crystal violet, PCR and qPCR. In total, 96.8% of S. aureus were strong in biofilm formation in contrast to 48.4% of S. epidermidis. sdrG and sdrF genes were present in 100% of S. epidermidis strains and in all isolates. In S. aureus, specific genes that code for MSCRAMM proteins were detected: clfA (89%), clFB, sdrC and fnBA (94%). The peptides did not show hemolytic or cytotoxic activity. In this study, it was evidenced that of the peptides DLL37-1 at a 5 µM concentration was an efficacious antimicrobial agent and depicted greater biofilm inhibition in both bacterial species. Exhibiting a significant inhibition rate in S. aureus, this peptide caused a negative regulation in the expression of the genes clfA and sdrC, showed greater biological activity.

Resumen Objetivo: estandarizar una qPCR para la determinación de T. pallidum en muestras de suero de pacientes con sífilis gestacional y congénita. Materiales y métodos: se optimizó una qPCR con sonda para la amplificación del gen TpN47 en muestras de suero, se evaluó la sensibilidad, especificidad y eficiencia analítica de la técnica. Se comparó con pruebas serológicas (VDRL y TPPA) y se calculó índice de concordancia Kappa. Resultados: la qPCR mostró un límite de detección de 0.113 femtogramos, especificidad analítica del 100% y fidelidad de 104%. Se evidenció correlación optima en la prueba, sugerida por un r2 de 0.99 y un valor p <0,0001 de la qPCR. Se observó acuerdo entre las pruebas serológicas y moleculares. Conclusiones: se desarrolló una herramienta molecular prometedora con buena sensibilidad, óptima especificidad analítica y gran potencial diagnóstico para la detección y hallazgo de T. pallidum subsp. pallidum, a través de la amplificación del gen TpN47 en muestras clínicas de pacientes con diagnóstico presuntivo de sífilis gestacional y congénita.

Abstract Objective: to evaluate a qPCR to detect T.pallidum in serum samples from patients with gestational and congenital syphilis. Methodology: qPCR with probe was optimized for the amplification of the TpN47 gene in serum samples, the sensitivity, specificity and analytical efficiency of the technique were evaluated. It was compared with the serological tests (VDRL and TPPA) and the Kappa concordance index was calculated. Results: the qPCR showed a detection limit of 0.113 femtograms, an analytical specificity of 100% and an accuracy of 104%. Optimal correlation was evidenced in the test, suggested by an r2 of 0.99 and a p value <0.0001 of the qPCR. An agreement was observed between serological and molecular tests. Conclusion: a promising molecular tool was developed with good sensitivity, excellent analytical specificity and great diagnostic potential for the detection and finding of T. pallidum subsp. pallidum, through the amplification of the TpN47 gene in serum from patients with gestational and congenital syphilis.