3-12 LOW RISK OF BACTEREMIA DURING CATHETER REPLACEMENT IN PATIENTS WITH LONG-TERM URINARY CATHETERS
The most important risk factor for urosepsis is pre-existing bacteriuria. Patients with long-term urinary catheters ultimately develop bacteriuria.
Does replacement of the catheter cause bacteremia?
Conclusion: Rarely.

STUDY

1. Analyzed clinical signs and symptoms and laboratory measurements during 120 routine catheter replacements in 39 geriatric patients. (Mean age 85)
2. All had bacteriuria—mainly enterobacteriaceae and enterococci.

RESULTS

1. Of 480 blood cultures (done at 5, 15, and 30 minutes after replacement) 5% were positive. However, the same species grew from both the blood and urine in only 5 catheter replacements. These were considered true catheter replacement bacteremias.
2. There were no significant differences in clinical or laboratory findings between patients with and without bacteremia. No patient met criteria for systemic inflammatory response syndrome.
3. Twelve blood cultures yielded coagulase-negative staphylococci (CNS). Although there was no CNS growth in the urine cultures of these patients, 16% of cultures of the removed catheter yielded CNS.
4. Urethral bleeding occurred in 3 of the 5 patients with bacteremia— none in 115 catheter replacements without bacteremia.

DISCUSSION

1. Similar to intravascular devices, transurethral catheters constitute a site for microbial adherence. Thick layers of bacterial biofilms have been observed on the surface of indwelling catheters. Bacteriuria is inevitable and continuous. (In the absence of catheters, bacteriuria in the elderly is often transient.)
2. Antimicrobial agents frequently fail to eradicate microorganisms in the urine of patients with long-term catheters.
3. In some nursing homes in Switzerland a single dose of trimethoprim-sulfamethoxalole or norfloxacin is given routinely during catheter replacement. There is no proof for the effectiveness of this approach.
4. In this study, bacteremia occurred in few patients after catheter replacement. All episodes were clinically irrelevant.
5. Antibiotic prophylaxis during catheter replacement is not indicated in geriatric patients with long-term urinary catheters.
6. Urethral bleeding, as a sign of mucosal lesion, was the only detectable risk for bacteremia. This occurs more frequently after traumatic replacement of a severely encrusted catheter.
7. Coagulase-negative staphylococci are part of the normal urethral flora. They adhere firmly to plastic surfaces. The authors hypothesized that CNS from the catheter surface may cause bacteremia if urethral damage occurs during catheter removal.

CONCLUSION
Bacteremia induced by routine replacement of long-term urinary catheters in geriatric patients is a rare event, most likely to occur if replacement causes bleeding. In this study such bacteremia did not have clinical relevance.

Archives Int. Med. March 10, 1997; 157: 521-25 Original investigation from University Hospitals, Basel, Switzerland

Comment:
The observation that the correlation between bleeding noted on removal of the catheter (due to mucosal trauma) and bacteremia is clinically significant. These patients should be more closely observed for urosepsis.
The avoidance of routine antibiotic prophylaxis is clinically and epidemiologically important.
Should prophylaxis be given to the subset of patients at risk for bacterial endocarditis? The latest recommendations of the American Heart Association on the prevention of bacterial endocarditis (JAMA June 11, 1997 comments (p 1797-98): Endocarditis prophylaxis is recommended for prostatic surgery, cystoscopy, and urethral dilation. "The rate of bacteremia following urinary tract procedures is high in the presence of urinary tract infection." "although bacteremia due to gram-negative bacilli is unlikely to cause endocarditis unless a prosthetic valve is present, it may nevertheless cause life-threatening sepsis. Therefore, an antimicrobial regimen effective against the infective urinary pathogen, eg, enteric gram-negative bacilli, in addition to the enterococcus, should be administered before the invasive genitourinary procedures."
The recommendations are not clear regarding catheter replacement. The table of p 1798 does not suggest prophylaxis, but the text suggests it should be given. I believe most clinicians would give prophylaxis in high risk patients during catheter replacement. RTJ

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