Multidrug-Resistant Bacteremia in Northern Taiwan: Focusing on Prognostic Factors and Antimicrobial Susceptibility to Minocycline and Rifampin.

Purpose: is an emerging multidrug-resistant pathogen associated with high mortality, particularly in healthcare-associated bacteremia. Treatment is complicated by frequent species misidentification and limited availability of effective antibiotics. This study aimed to investigate the clinical characteristics, predictors of early and late mortality, and antimicrobial resistance profiles, including associated resistance genes.

Patients And Methods: A retrospective cohort study was conducted from 2018 to 2022 at a center in northern Taiwan, involving patients with bacteremia. Demographic and clinical data, including comorbidities and laboratory parameters, were collected. Clinical severity was assessed using the Pitt bacteremia score. Bacterial isolates were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and species-specific polymerase chain reaction. Antimicrobial susceptibility was determined using broth microdilution, and resistance genes were detected by PCR.

Results: The 14-day and 28-day mortality rates after admission were 35% and 40%, respectively. The 14-day mortality rate was associated with high Pitt bacteremia scores, chronic kidney disease, anemia, and hyperbilirubinemia. Anemia and high Pitt bacteremia scores were consistently associated with 28-day mortality. Most isolates were phenotypically resistant to β-lactams, fluoroquinolones, and trimethoprim-sulfamethoxazole, while susceptibility to minocycline (1.6%) and rifampin (9.5%) was preserved. The detected resistance genes included multiple determinants ( , and ), with a notable absence of .

Conclusion: bacteremia is associated with higher mortality and multidrug resistance. Prognosis is significantly influenced by host factors and specific laboratory findings. Given the high resistance of these bacteria to traditional antibiotics, minocycline and rifampin may serve as key treatment options when susceptibility is confirmed. Further studies are needed to validate their clinical efficacy, dosing, and combination strategies.