Problem:
A 70-year-old patient with a peripherally inserted central catheter (PICC) develops a bloodstream infection. The organism is sensitive to the prescribed antibiotic based on laboratory testing. After 7 days of appropriate therapy, blood cultures remain positive. The provider suspects that bacteria have formed a biofilm on the catheter surface, preventing eradication of the infection. Which structural feature of the biofilm explains why this patient's infection persists despite appropriate antibiotic therapy? Need Assignment Help? Flagellar structures that enhance bacterial motility in the bloodstream Thick peptidoglycan layers that reinforce bacterial cell wall structure Phospholipid membranes that increase bacterial metabolic activity Extracellular polymeric substances that form a protective matrix