Relationship between faecal metronidazole and lactoferrin concentrations to clinical response of patients with Clostridioides difficile.

Objectives: We investigated patients with Clostridioides difficile-associated diarrhoea to see if clinical resolution correlated with faecal concentrations of metronidazole or markers of inflammation.

Methods: Faecal metronidazole, lactoferrin and serum CRP were measured daily. These were then compared with clinical progress.

Results: Metronidazole concentration correlated with lactoferrin (ρ = 0.17, p = 0.015), CRP (ρ = 0.23, p < 0.001) and number of diarrhoeal stools per day (ρ = 0.29, p < 0.001). Lactoferrin correlated with CRP (ρ = 0.57, p < 0.001) and the number of diarrhoeal stools per day (ρ = 0.52, p < 0.001) as did CRP (ρ = 0.52, p < 0.001).

Conclusions: We found no association between cessation of diarrhoea and metronidazole or lactoferrin concentrations. There was a relationship between metronidazole concentrations and markers of inflammation and stool frequency.