Study of layered double hydroxides as bactericidal materials against Corynebacterium ammoniagenes, a bacterium responsible for producing bad odors from human urine and skin infections

If diapers are infrequently changed, they are subjected to an excess of hydration causing bad smells and skin irritation. These problems are mainly induced by a bacterium present in human urine, Corynebacterium ammoniagenes. The bacterial growth can be avoided by bactericidal agents, such as the anionic clays or layered double hydroxides (LDH) that can be modified chemically by introducing bactericidal ions, such as Zn cations, into the LDH lamellae arrangement. In this work, for the first time, the effectiveness of layered double hydroxides with various compositions as antibacterial agents against C. ammoniagenes was evaluated. Two in vitro procedures were carried out; the first was a modified Kirby Bauer method, and the second was a broth-dilution method for performing antimicrobial susceptibility. The layered double hydroxides were characterized by X-ray diffraction, FT infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and thermogravimetric and differential thermal analyses. The results show that layered double hydroxides containing copper or magnesium as divalent cations were not active against C. ammoniagenes, whereas those containing zinc, as a divalent cation presented excellent bactericidal activity; this being proven by a 98.1% reduction in the C. ammoniagenes colonies after 24 h of contact time with only 20 mg of LDH/mL or 99.9% reduction with 50 mg/mL.