Epithelial lining fluids contain high concentrations of the antiinfective proteins lysozyme, secretory phospholipase A2, the surfactant proteins A and D (SP-A and SP-D), as well as several types of antiinfective peptides.
In the case of antimicrobial activity, these antiinfective peptides/proteins appear to share a common mechanism of action, targeting the outer membrane, resulting in membrane disruption and dysfunction.
'Defensin' is the collective term for a large family of antiinfective peptides which, like cathelicidins, possess broad-spectrum antiinfective properties encompassing gram-positive and gram-negative bacteria, fungi and yeasts, as well as many enveloped and non-enveloped viruses.
Here the pathogen is bombard-ed by an array of two main types of toxic agents: (i) preformed antiinfective granule proteins; and (ii) newly synthesised reactive oxygen and reactive nitrogen species generated by the enzymes NADPH oxidase (acting in concert with the primary granule enzyme myeloperoxidase) and nitric oxide synthase, respectively.
Among these innovations are using antiinfective lubricants when inserting the catheter; soaking the catheter in an antiinfective antimicrobial-drug solution before insertion; regular metal cleansing or periodically applying antiinfective creams or ointments to metals; continuously irrigating the catheterized bladder with an antiinfective solution through a triple-lumen catheter; or periodically instilling an antiinfective solution into the collection bag (Table 4).
Two catheters impregnated with antiinfective solutions have been studied in randomized trials, one impregnated with the urinary antiseptic nitrofurazone (20) and the other with a new broad-spectrum antimicrobial-drug combination, minocycline and rifampin (21).
The first major advance for preventing CAUTI since the wide-scale adoption of closed drainage 35 years ago is the development of catheters with antiinfective surfaces.