In vivo bioluminescence to detect the attachment of L-forms of Listeria monocytogenes to food and clinical contact surfaces

A bioluminescent phenotype of Listeria monocytogenes was employed to study the adhesion and biofilm formation of both classical and L-forms to relevant food and clinical contact surfaces. Attachment of both parental (cell-walled) and L-forms to intravenous tubing and stainless steel was compared using viable counts and bioluminescence. Both cell types attached themselves to intravenous tubing and stainless steel. Parental cell numbers attached to intravenous tubing were 1 log higher than L-form numbers, and on stainless steel, attached L-form numbers were 1 log higher. Bioluminescence measurements yielded a pattern similar to viable count measurements. There was a clear relationship between light output of attached bacteria and their viability and, thus, a bioluminescent phenotype provides a rapid monitor of both microbial viability and biofilm formation by L-forms.