Aim:Gram-negative nosocomial meningitis is difficult to treat because bacteria have become increasingly resistant to most common antibiotics. Attaining effective antibiotic concentration is difficult when treatment is given intravenously (IV), because blood-brain barrier decreases antibiotic penetration. Due to this reason, intrathecal (IT) and intraventricular (IVT) antibiotics have been subjects evaluated in past studies. In this study, we aimed to evaluate the gram-negative nosocomial meningitis cases which were treated with IT/IVT antibiotics.Material and Methods:Medical records were reviewed for IT/IVT antibiotherapy. Gram-negative nosocomial meningitis cases treated with IT/IVT antibiotherapy additional to systemic antibiotics were included. All patients’ sex, age, SOFA scores, surgical history, cerebrospinal fluid (CSF) culture results, CSF cell counts, systemic and IT/IVT antibiotics, their dosages and duration, CSF culture sterility and sterility time, 28-day mortality due to meningitis, and all other causes were recorded and analyzed.Results:Thirteen patients were included between 2014 and 2018. Most common microorganism was Acinetobacter baumannii (A.baumannii) (8/13). IT/IVT antibiotics were chosen according to susceptibility. Colistin was used in eight patients, amikacin was used in four, and one patient used amikacin and colistin consecutively. Culture negativity could not be achieved in two patients. Eight patients clinically improved but five patients had no clinical response. 28-day mortality due to infection occured in 2 of 13 patients (15%). 28-day all-cause mortality occured in 3 of 13 patients (23%). Conclusion:In our study, CSF culture negativity rate was high. IT/IVT antibiotic therapy should be considered as an effective and acceptable treatment option, especially in patients who do not respond to standard IV antibiotherapy.