Surfactants may affect the treatment of lower respiratory tract infections. In addition, other bodily fluids such as urine and serum can also affect antimicrobial activity. Therefore, the effects of detergent, urine, and serum on the antibacterial activity of a novel β-lactam/β-lactamase inhibitor combination of cefepime-enemetazobactam (FPE) were determined. 10 clinical isolates Klebsiella pneumoniaeand quality control strains Klebsiella pneumoniae ATCC 700603 and Escherichia coli NCTC 13353 was tested. Minimum inhibitory concentration (MIC) determination (all strains) and time kill curves (TKC) of FPE and piperacillin-tazobactam (TZP) with or without the surfactant formulation Survanta® (SUR; 1% v/v) (one clinical isolate) was measured. and Curosurf® (CUR; 1 mg ml-1).Determination of daptomycin MIC against Staphylococcus aureus ATCC 29213 in the presence and absence of detergent was used as a positive control. In addition, the effect of growth media supplemented with pooled human urine or serum was also assessed by MIC testing. As expected, medium supplemented with SUR increased the daptomycin MIC. Staphylococcus aureus ATCC 29213. In contrast, detergent did not affect the antibacterial activity of FPE against the Enterobacterales isolates tested. TKC experiments also revealed no effect of CUR on the antibacterial activity of FPE. These results indicate that the antibacterial activity of FPE is unaffected in the presence of pulmonary surfactant. Furthermore, FPE was not affected by media supplemented with urine or serum.