Oldenlandia diffusa Extract Inhibits Biofilm Formation by Haemophilus influenzae Clinical Isolates

Abstract

Oldenlandia diffusa has been empirically used as a therapeutic adjunct for the treatment of respiratory infections. To establish the basic evidence of its clinical usefulness, antimicrobial and biofilm inhibitory activities of an O. diffusa extract were examined against clinical isolates of Haemophilus influenzae, a major causative pathogen of respiratory and sensory organ infections. No significant growth inhibitory activity was observed during incubation for more than 6 h after the extract addition into a culture of H. influenzae. On the other hand, biofilm formation by H. influenzae, evaluated by a crystal violet method, was significantly and dose-dependently inhibited by the O. diffusa extract. Furthermore, the mRNA level of the biofilm-associated gene luxS of H. influenzae significantly decreased soon after the extract addition, and the suppressive effect continued for at least 2 h. At 2 h after the addition of the O. diffusa extract, the autoinducer in the culture supernatant was also significantly reduced by the O. diffusa extract in a dose-dependent manner. These results revealed that O. diffusa extract shows inhibitory activity against luxS-dependent biofilm formation but has no antimicrobial activity against planktonic cells of H. influenzae. Thus, O. diffusa extract might be useful as an adjunctive therapy for the treatment of respiratory infections caused by H. influenzae.

Otitis media pathogens – A life entrapped in biofilm communities

“…Natural and synthetic compounds have also been investigated for the control of biofilms formed by H. influenzae. For instance, pyrazol derivatives (Kosikowska et al 2014), chalcones (Kunthalert et al 2014), plant extracts (Wajima et al 2016), nitric oxide (Collins et al 2016), proteins (Dawe et al 2017), and honey (Newby et al 2018), among others, have shown positive effects.…”

Kampo medicines suppress the production of exfoliative toxins causing impetigo in Staphylococcus aureus

“…11 To discover agents exhibiting antivirulence activity other than antimicrobial agents, we have screened various herbal medicines, including the Kampo medicines. [12][13][14][15] Although some Kampo medicines were used successfully to treat pyogenic dermatitis, 16 no case was reported of patients with impetigo being treated by any Kampo medicines. Decreased production and virulence of ET lead to the alleviation of the symptoms of impetigo and prevent SSSS.…”

Shiunko and Chuoko, topical Kampo medicines, inhibit the expression of gehA encoding the extracellular lipase in Cutibacterium acnes

“…However, a heavy use of antibiotics causes an increase in bacterial resistance, limiting the continued use of antimicrobial treatment for acne . Some natural medicines with antimicrobial and antipathogenic activity have been reported . Kampo medicines, traditional Japanese herbal medicines, have been used for acne treatment.…”

“…6 Some natural medicines with antimicrobial and antipathogenic activity have been reported. 7,8 Kampo medicines, traditional Japanese herbal medicines, have been used for acne treatment. Of these, Keigairengyoto, Seijoboufuto and Jumihaidokuto are considered as one of the options in acne treatment guidelines.…”