The use of antibiotics to treat bacterial infections is becoming less and less effective year by year due to the increasing resistance of bacteria. The microbial evolutionarily acquired resistance to antibiotics increases the threat to man's life due to difficulties regarding effective therapies to fight infections. Therefore, apart from treatment, it is necessary to introduce appropriate prophylaxis which limits the multiplication of bacterial colonies on everyday use objects. Due to the antibiotic resistance phenomenon, it is important to find a new material with antibacterial properties for FDM 3D printing in medical applications. The work contains research on a new chemical compound used as an additive to thermoplastics. The rhodamine derivative was synthesized via the 4-diphenylaminobenzaldehyde reaction with 1.3-indendione in a boiling mixture of EtOH/H2SO4. The obtained chemical compound was used as a bacteriostatic modifier of the polycarbonate (PC) properties, as such a modification enables application e.g. for medical device housings or for surfaces frequently touched by people. The modifier and the commercially available polymer were compounded with a high-temperature screw extruder and a filament for FDM 3D printer was created. The modified polymer revealed antibacterial properties relative to Escherichia coli and good thermal stability during the processing.