Recce Pharmaceuticals (ASX:RCE) said its R327 therapy candidate showed antibacterial activity against multidrug-resistant Acinetobacter baumannii in a study of the therapeutic efficacy of R327 in a validated model of hospital/ventilator-acquired pneumonia, according to a Wednesday Australian bourse filing.

Around 40 female mice, assigned to seven treatment groups, received, via intranasal drops or nebulization, either R327, placebo, saline, or meropenem, a "last resort" treatment, which can cause severe liver injury, per the filing.

At 24 hours post-infection, animals treated with R327 showed a significant reduction in bacterial load in the lungs compared with both the untreated and placebo groups. Both intranasal and nebulised R327 significantly reduced colony-forming units.

Nebulized R327 treatment resulted in a four-log reduction, corresponding to over 99.99% lower bacterial burden in the lungs and achieving bacterial counts approaching the lower limit of detection.

Meropenem also reduced bacterial numbers, but it can only be delivered intranasally due to solubility constraints, it added.

Recce's shares rose 2% in recent trading on Wednesday.