Clinical Use of Parenteral Fosfomycin: The Mersin Experience

The global increase in carbapenem-resistant Enterobacteriaceales (CRE) species and non-fermentative Gram-negative bacilli causing healthcare-associated infections is a serious public health problem. Polymyxins and fosfomycin have regained importance, but their monotherapy effectiveness is limited. High-dose parenteral fosfomycin may cause hypernatremia due to high sodium content. This study aims to share clinical experiences with parenteral fosfomycin use. This retrospective, observational study in a tertiary university hospital included 37 patients (≥18 years) who received IV fosfomycin for at least 48 hours. The clinical efficacy of fosfomycin and the effects of creatinine on the changes in glomerular filtration ratio (EGFR) in sodium and potassium were evaluated. 67.6% of the patients were male, mean age 56.7±20.3 (18-87). 43.22% of cases were in the intensive care unit. Main indications were bone-joint infections (44.5%) and device-related infections (21.8%). All patients had at least one multidrug-resistance (MDR) growth ( A.baumannii 59.5%, K.pneumoniae 43.2%). 97.3% received combination therapy. Treatment success was 64.9%, with 48.6% mortality. There was no significant change in creatinine, e-GFR, and potassium values during treatment (p>0.05), hypernatremia increased significantly (p=0.001). Fosfomycin was used rationally, mainly in combination therapy for confirmed MDR infections. Despite no usage limitations in guidelines, empirical treatment was only initiated for urinary tract infections. MDR Gram-negative bacilli are increasing, causing treatment failures and mortality in critical or chronic cases. Hypernatremia, also detected in our study, was a significant concern, highlighting the need for sodium restriction and close monitoring during treatment, especially in elderly patients.