Antibacterial Activity of Heteropolytungstates Against Proteus mirabilis

The emergence of multidrug‐resistant Proteus mirabilis ( P. mirabilis ) in urinary tract infections necessitates new antimicrobial strategies. Here, we investigated the in vitro antibacterial activity of several tungstophosphates, the monovacant Keggin ion PW 11 O 39 7− ( PW 11 ), the monovacant Wells–Dawson ion P 2 W 17 O 61 10− ( P 2 W 17 ), the complete Wells–Dawson ion P 2 W 18 O 62 6− ( P 2 W 18 ), and the Preyssler–Pope–Jeannin ion NaP 5 W 30 O 110 14− ( P 5 W 30 ), at physiological pH against P. mirabilis . Antibacterial efficacy was evaluated using agar well‐diffusion and broth microdilution assays. A structure–activity relationship was observed, with potency increasing in the order PW 11 < P 2 W 17 < P 2 W 18 < P 5 W 30 . The P 5 W 30 exhibited the highest inhibitory activity with the lowest minimum inhibitory concentration (MIC) of 0.78 mg/mL, corresponding to a POM concentration of 0.095 mM, whereas P 2 W 18 reached bactericidal levels with a minimum bactericidal concentration (MBC) of 12.5 mg/mL (2.57 mM).