A study of nosocomial infections involving urinary catheters is performed. The study shows that the longer an indwelling urinary catheter remains, the higher the rate of symptomatic urinary tract infections (UTIs). Most of these infections are bacterial. Which of the following properties of these bacteria increase the risk for nosocomial UTIs?
Microbes form biofilms of sticky polysaccharide goo that adheres particularly well to artificial surfaces such as catheters. The biofilm helps isolate the organisms from inflammatory cells and limit the penetration of antibiotics. Bacterial enzymes, such as the hyaluronidases and streptokinases of streptococcal organisms, promote spread through tissues. Exotoxins of gram-positive organisms impart virulence through tissue damage. Bacteria have multiple mechanisms for exchanging genetic material that affords selective growth advantages. When the number of bacterial organisms increases, they sense this (quorum sensing) and turn on virulence genes. Organisms such as Staphylococcus aureus can express superantigens that non-selectively stimulate many T cell clones, leading to unregulated cytokine release and toxic shock.
Biofilm formation
Enzyme elaboration
Exotoxin release
Quorum sensing
Infectious Disease