Adequacy of sanitization and storage of catheters for intermittent use after washing and microwave sterilization

Clean intermittent catheterization is used to treat neurogenic bladders and it can be adequate to maintain sterile urine. Typically polyvinylchloride, individually packaged catheters are used but they are not intended for repeat use by the manufacturer. Antibacterial soap alone or combined with microwave heating was advocated to decrease pathogens and bacterial residue, which could inoculate the bladder from a colonized catheter. We assessed the efficacy of catheter sanitizing and storage for reuse.

Catheters were inoculated with a 24-hour broth culture of Escherichia coli and washed in antibacterial soap, washed and microwaved or immediately packaged (positive controls) and stored for 1, 3 and 7 days, respectively. Common packaging was used, including paper towels, sealable plastic bags or sealable rigid plastic containers. Each condition was assessed in triplicate via culture of the entire catheter contents, yielding a total of 27 catheters per sanitization method.

Antibacterial wash alone failed to sanitize 67% of catheters (6 of 9 with 2 of 3 positive per container) on day 1, 22% (2 of 9 with all positive catheters in a paper towel) on day 3 and 44% (4 of 9 with 1 in a paper towel and 3 in a plastic container) on day 7. For combined antibacterial wash and microwave heating the positive rate was 0% (0 of 9 catheters) on day 1, 22% (2 of 9 in a plastic container) on day 3 and 56% (5 of 9 with 3 in a paper towel, 1 in a plastic bag and 1 in a plastic container) on day 7. Positive untreated controls showed viable organisms throughout the test period.

Overall 44% of catheters (12 of 27) washed with antibacterial soap yielded E. coli vs 26% (7 of 27) with combined antibacterial soap-microwave treatment. The latter is a more effective but not an absolute way to sanitize catheters for intermittent use. Longer storage time increased the risk of E. coli growth on the catheters.