Retrospective Evaluation of Intravenous Fosfomycin in Multi-drug Resistant Infections at A Tertiary Care Hospital in İstanbul

Introduction: Fosfomycin has started to be used again as a possible therapeutic alternative in cases injected with resistant bacterial pathogens. Its primary mechanism of action is inhibition of the first step of cell wall synthesis; This mechanism is effective against both Gram-positive and Gram-negative bacterial groups. However, its clinical efficacy against bacteria that develop multidrug resistance is largely unknown. Therefore, we aimed to evaluate the clinical and microbiological efficacy of intravenous Fosfomycin in a tertiary care center. Methods: The group of adult patients aged 18 years and over who applied to the hospital between January 2018 and December 2022 and were given intravenous fosfomycin therapy for at least 24 hours due to any infection were retrospectively analyzed.Results: 71 patients were included in our study. The female/male ratio of these patients was 35/36, and the mean age was 61.5±17.0 (18-84). The avarage time to treatment was 10.6 days (11.3-+11.4). 22 patients (31%) from Intensive Care Unit and 49 (69%) patients from other clinics were included in the study. 18 bacteremia (26%), 15 pneumonia (21%), 14 wound infections (19%), 13 ventilator-associated pneumonia (18%), 5 urinary tract infections (UTI) (8%), 4 abdominal infections (6%) and 2 endocarditis (3%). Detected causative microorganisms were 18 Extensively Drug-Resistant (XDR) Klebsiella pneumoniae, pandrug resistan Klebsiella pneumoniae (17.5%), 5 MRSA (12.5%), 5 pandrug resistan Pseudomonas aerinosa (12%), 4 Escherichia coli (10%), 1 Acinetobacterbaumanii (2.5%) and 1 Enterobacter spp. (2.5%). Looking at the underlying diseases, one of our patients had diabetes mellitus and another patient had chronic renal failure. Mean procalcitonin (PCT) and C reaktive protein (CRP) (cutoff value0.5 ng/mL) values were 2.53±1.2 ng/ml and 89.7±21.9 mg/dl, respectively. Median sodium (Na), potassium (K), AST, ALT, and creatinine values of the patients before and after fosfomycin IV treatment were calculated and there was no statistically significant difference.Clinics combined with fosfomycin IV were as follows: 31 meropenem (44%), 15 colistin (26%), 18 tigecycline (26%), 3 vancomycin (4%), 3 amikacin (4%) and 1 daptomycin (1%). Conclusions: According to the results of our study, it was seen that Fosfomycin is a safe and effective option in the treatment of multidrug-resistant infections. Accordingly, our results are compatible with the literature.