Antimicrobial resistance in cardiac surgery: a narrative review of pathogens, mechanisms, diagnostics, and therapeutic frontiers

Infections following cardiac surgery represent a significant cause of morbidity and mortality, exacerbated by the global rise of antimicrobial resistance (AMR). The pathogen landscape has shifted from a dominance of Gram-positive organisms such as methicillin-resistant Staphylococcus aureus (MRSA) to include a critical threat from multidrug-resistant (MDR) Gram-negative bacteria, including carbapenem-resistant Enterobacterales (CRE), Pseudomonas aeruginosa, and Acinetobacter baumannii. This review summarizes current knowledge on key pathogens, their resistance mechanisms, and evolving diagnostic and therapeutic strategies in the cardiac surgery setting. The review highlights the impact of mobile genetic elements and biofilms on infection persistence, particularly on prosthetic materials such as heart valves, pacemakers, and grafts. Advanced diagnostics, including rapid molecular methods like multiplex polymerase chain reaction (PCR) and next-generation sequencing (NGS), allow for faster pathogen and resistance detection. However, their clinical utility requires careful stewardship to avoid misinterpretation. Novel antibiotics offer important treatment options for MDR organisms but face emerging resistance challenges. Furthermore, complex pharmacokinetic and pharmacodynamic (PK/PD) alterations during cardiopulmonary bypass can lead to subtherapeutic drug concentrations, undermining efficacy. Effective AMR management in cardiac surgery demands a multidisciplinary approach that integrates rapid diagnostics, evidence-based pharmacotherapy, source control, and antimicrobial stewardship. Ongoing innovation in therapeutics, personalized dosing, and diagnostics remains vital to improving outcomes and preserving antibiotic efficacy in this vulnerable patient population. Future research into anti-biofilm therapies and other non-traditional approaches is critical.