Evaluation of In Vitro Biofilm Formation of Leptospira Isolates From Human Samples at Four Different Time Frames

Biofilm is a group of bacterial cells that are formed through a complex network of intracellular communication, which gives new properties to those organisms, like increased protection and resistance to antimicrobial agents, and decreases the effectiveness of host immune responses. Detection of biofilm and evaluation of biofilm production at different time frames are important parameters for antimicrobial resistance, with no or delayed improvement in patient outcomes even after prolonged antimicrobial therapy.

This was an experimental research using 33 human Leptospira isolates. Biofilm formation was checked by a quantification method using 96-well polystyrene U-well plates. Biofilm formation was checked on days 5, 7, 14, and 21.

The biofilm optical density (OD) remained relatively low and stable on Day 5 (0.0703) and Day 7 (0.0674), with overlapping 95% Cls, suggesting no significant difference between these two time points. However, a marked increase was observed by Day 14, where the OD rose to 0.1189 (95%CI: 0.0986-0.1391), indicating a significant accumulation of biofilm. This upward trend continued through Day 21, with the highest mean OD recorded at 0.1826 (95% CI: 0.1596-0.2055). The widening confidence intervals on Days 14 and 21 reflect increased variability at later stages.

Human Leptospira isolates show potential for biofilm production in a time-dependent manner. In the present study, OD of biofilm remains low and stable on days 5 and 7, with a marked increase in OD seen on Day 14 and much on Day 21.