Biofilms on indwelling medical devices are a major public health concern due to their resistance to antimicrobial treatments and ability to cause infections. These biofilms consist of microorganisms attached to surfaces, often forming a matrix of extracellular polymeric substances. They are more resistant to antimicrobial agents than free-floating (planktonic) cells and can lead to serious infections such as those associated with central venous catheters, mechanical heart valves, and urinary catheters. Microorganisms that form biofilms on these devices include bacteria and yeasts, often originating from the patient's skin, healthcare workers, or environmental sources. Biofilms on urinary catheters, for example, can develop into multispecies biofilms over time, leading to urinary tract infections. Biofilms on central venous catheters are commonly composed of Staphylococcus epidermidis and Staphylococcus aureus, while those on mechanical heart valves are often caused by Staphylococcus epidermidis, Staphylococcus aureus, and gram-negative bacteria. Factors influencing biofilm formation include the type and number of microorganisms, the flow rate of fluids, and the physicochemical properties of the device surface. Biofilms are difficult to treat and can lead to severe infections, such as prosthetic valve endocarditis. Antimicrobial treatments, including silver-coated devices and antimicrobial agents, have been explored to prevent biofilm formation. Research is needed to develop better methods for detecting and measuring biofilms, as well as to understand their role in antimicrobial resistance and infection. Model systems are essential for studying biofilm processes on various devices. Additionally, understanding the communication between cells within biofilms could lead to more effective strategies for preventing and treating biofilm-related infections. Future research should focus on improving biofilm control strategies and clarifying the link between biofilm contamination and patient infections.Biofilms on indwelling medical devices are a major public health concern due to their resistance to antimicrobial treatments and ability to cause infections. These biofilms consist of microorganisms attached to surfaces, often forming a matrix of extracellular polymeric substances. They are more resistant to antimicrobial agents than free-floating (planktonic) cells and can lead to serious infections such as those associated with central venous catheters, mechanical heart valves, and urinary catheters. Microorganisms that form biofilms on these devices include bacteria and yeasts, often originating from the patient's skin, healthcare workers, or environmental sources. Biofilms on urinary catheters, for example, can develop into multispecies biofilms over time, leading to urinary tract infections. Biofilms on central venous catheters are commonly composed of Staphylococcus epidermidis and Staphylococcus aureus, while those on mechanical heart valves are often caused by Staphylococcus epidermidis, Staphylococcus aureus, and gram-negative bacteria. Factors influencing biofilm formation include the type and number of microorganisms, the flow rate of fluids, and the physicochemical properties of the device surface. Biofilms are difficult to treat and can lead to severe infections, such as prosthetic valve endocarditis. Antimicrobial treatments, including silver-coated devices and antimicrobial agents, have been explored to prevent biofilm formation. Research is needed to develop better methods for detecting and measuring biofilms, as well as to understand their role in antimicrobial resistance and infection. Model systems are essential for studying biofilm processes on various devices. Additionally, understanding the communication between cells within biofilms could lead to more effective strategies for preventing and treating biofilm-related infections. Future research should focus on improving biofilm control strategies and clarifying the link between biofilm contamination and patient infections.