VALIDATION OF A RAPID MALDI-TOF MS PROTOCOL FOR DIRECT BACTERIAL IDENTIFICATION FROM BLOOD CULTURES IN A PUBLIC HOSPITAL IN LIMA, PERU

Cucho Espinoza C.; Rivero Rodríguez L.; Yali Rivera J.M.; Condori Zevallos M.S.; Meneses Claudio J.P.J.; Abanto Pino J.C. · Revista de la Facultad de Medicina Humana (2026) · DOI: 10.25176/rfmh.v26i2.8258

Resumen

Introduction: Rapid bacterial identification from positive blood cultures is essential to improve sepsis management, especially in resource-limited settings. This study evaluated a rapid MALDI-TOF MS protocol using serum separator gel tubes. Objective: To assess the agreement between a rapid MALDI-TOF MS protocol applied directly from blood culture bottles and standard identification by MALDI-TOF MS from isolated colonies. Methods: A prospective diagnostic accuracy study was conducted, including 292 positive blood cultures collected between January and December 2023. The rapid method was compared with the standard MALDI-TOF MS method from colonies. Samples were processed using serum separator gel tubes, and agreement was assessed using Cohen's kappa coefficient and time to result. Results: A total of 292 positive blood cultures were analyzed: 52.8% were Gram-negative bacilli, 43.5% Gram-positive cocci, and 3.7% Gram-negative coccobacilli. The rapid protocol achieved correct identification in 93.6% of cases. Identification rates were 94.7% for Gram-negative isolates and 58.1% for Gram-positive isolates with scores ≥1.7. Agreement was excellent, with kappa values of 0.92 for Gram-negative bacteria and 0.89 for Gram-positive bacteria. The rapid method significantly reduced time to result compared with the standard method (42.72 vs. 1247.12 minutes; p<0.0001). Conclusions: The protocol showed high agreement and significantly reduced identification time, representing a cost-effective alternative for laboratories in resource-limited settings.

Instituciones: Universidad Nacional Mayor de San Marcos; Universidad Ricardo Palma