In vitro activity of Houttuynia cordata against bacteria isolated from diabetic foot.

Background: Misuse of antibiotics makes it very easy for bacteria to become resistant to drugs. Houttuynia cordata (HC) has antibacterial, antiviral, analgesic, antioxidant, diuretic, hypoglycemic, and immune-enhancing properties.

Aim: To study the inhibitory effect of HC on Staphylococcus aureus and Pseudomonas aeruginosa isolated from tissue or pus specimens from patients with diabetic foot ulcers.

Materials and methods: Seventy-two patients with DFU were randomly divided into three groups and given treatment with methicillin (Met), meropenem (Mer), and HC, respectively. Analysis and identification of clinical isolates of Staphylococcus aureus and Pseudomonas aeruginosa using the Orbitrap Exploris™ 480. The drug susceptibility of four isolates to HC was studied by bacteriostatic test. The MIC and MBC of Houttuynia cordata against four isolates were determined using the broth microdilution method. The growth and time-kill curves of the bacteria were studied by bacterial inhibition experiments.The effect of Houttuynia cordata on the viability of H6C7 cells was examined by MTT assay.

Results: HC treatment improved clinical parameters of DFUs patients. The inhibition zone of S08 (MSSA) was 15.45 ± 0.12 mm, which was highly sensitive to Houttuynia cordata. The inhibition zone sizes of R11 (MRSA), P10 (CRPA) and D22 (MDRPA) were 12.64 ± 0.09 mm,13.42 ± 0.11 mm and 11.23 ± 0.08 mm, respectively. All of them were moderately sensitive to Houttuynia cordata. The MIC of S08,R11,P10 and D22 were 31.25,62.5,62.5 and 125 µg/mL, respectively. The MBCS of S08,R11,P10 and D22 were 500,1000,1000 and 1000 µg/mLrespectively.Bacterial growth curves and time-kill curves demonstrated that Houttuynia cordata significantly inhibited the growth of both bacteria. Cytotoxicity assay showed that Houttuynia cordata effectively inhibited bacteria without cytotoxicity to eukaryotic cells.

Conclusion: Houttuynia cordata exhibits promising antibacterial activity against both Staphylococcus aureus and Pseudomonas aeruginosa, including drug-resistant strains, without cytotoxic effects on eukaryotic cells. These findings support its potential as an alternative therapeutic agent for DFU-associated infections.