Cadmium modulates biofilm formation by Staphylococcus epidermidis

Area of Science:

• Microbiology
• Environmental Science
• Toxicology

Background:

• Staphylococcus epidermidis is a common cause of implant-associated infections.
• Biofilm formation by S. epidermidis contributes to its persistence and resistance to antibiotics.
• The impact of environmental factors like heavy metals on S. epidermidis biofilm formation requires further investigation.

Purpose of the Study:

• To investigate the effect of cadmium exposure on Staphylococcus epidermidis biofilm formation.
• To determine the influence of sub-toxic cadmium concentrations on bacterial viability and gene expression related to biofilm.

Main Methods:

• Bacterial cultures of S. epidermidis (ATCC 35984) were exposed to varying cadmium concentrations (0-50 µM).
• Biofilm formation was quantified, and bacterial viability was assessed.
• Confocal laser scanning microscopy (CLSM) was used to measure biofilm thickness.
• Quantitative Real-Time PCR (qRT-PCR) analyzed the mRNA expression of biofilm-associated genes (atlE, embp, aap, icaA, icaB).

Main Results:

• Low cadmium concentrations (1.56 and 3.13 µM) significantly stimulated S. epidermidis biofilm formation (p<0.001).
• CLSM revealed increased biofilm thickness (23 µm and 22 µm) at these concentrations compared to controls (17.8 µm).
• qRT-PCR showed significant up-regulation of key biofilm genes (atlE, embp, aap, icaA, icaB) at 3.13 µM cadmium.

Conclusions:

• Cadmium, even at low, sub-toxic levels, acts as an inducer of Staphylococcus epidermidis biofilm formation.
• These findings highlight a potential environmental risk factor contributing to S. epidermidis-related infections.
• Understanding cadmium's role in biofilm development is crucial for developing effective prevention and treatment strategies.