Journal
of Hospital
Infection
(1991) 18, l-3
EDITORIAL
Prophylaxis
for catheter related infection
urinary
tract
Much has been published on the prevention of catheter related urinary infection, yet the subject still provokes thought, research and speculation. In this issue, Hustinx et al. (p. 45) show that the concurrent use of appropriate antibiotics within the 48 hours before catheter removal reduced the risk of bacteriuria five-fold. This result, taking as an end point bacteriuria as such, without assessing clinical outcomes, confirms previous work’ and is not unexpected because of the high concentrations of these antibiotics in urine. It also highlights a recurring problem in the analysis of reports of methods to prevent catheter induced urinary tract infections (UTIs), which so often fail to describe what proportions of patients concurrently received antibiotics. As Hustinx et al. point out, in Kunin & McCormack’s2 trial of closed sterile drainage 84% of their patients received antimicrobials at some stage, and the relative contributions of antimicrobials and closed drainage are consequently less clear. In the survey of Hustinx et al. only 27% of the cases of bacteriuria were accompanied by pyuria. Thus, in most of their patients, only bacteriuria occurred following short-term catheterization. Bacteriuria plus pyuria usually indicates bacterial infection of the tissues of the urinary tract. Bacteria limited to the urine are not causing bladder infection and are not in contact with the blood stream and presumably the danger of bacteriuria by itself, as a cause of infection at distant sites, is less than when there is local tissue invasion. How often and how quickly do the bacteria introduced by the catheter actually invade the tissues of the urinary tract? Could bacteriuria simply reflect urethral organisms pushed into the bladder by the catheter and immediately washed out in the urine sample? Mechanical irritation of the urethra and bladder mucosae by the catheter can also result in pyuria; thus, a further marker along the route of the pathological consequences of catheterization is the development of symptoms of UTI, which distinguish mechanical irritation from bacterial infection. The occurrence of bacteriuria following catheterization seems inevitable with time. The number of bacteria introduced by the catheter even in normal subjects,3 and the speed with which bacteriuria is established, demonstrate the powerful effect of the catheter. This is reflected in the long and unsuccessful history of attempts to prevent catheter induced urinary infection. Most preventative methods involving local disinfection and catheter related techniques have failed in routine use or are not yet practical. 0195-6701/91/050001+03
SO3.00/0
Q 1991 The Hospital
1
lnfectmn
So&t)
2
Editorial
Is it time to consider antibiotic prophylaxis for the problem, as Hustinx et al. suggest? In favour is the demonstrated fact that antibiotics can overcome of bacterial the powerful effect of the catheter; against is the problem resistance and the lack of data as to how often local tissue invasion and distant infection at sites outside the urinary tract actually occur. In the urinary tract bacteriuria by itself seems not to be damaging and usually disappears when the catheter is removed. Asymptomatic bacteriuria is common in elderly females and increases with age in males. It is repeated requiring in patients continuously present frequently catheterization or long-term catheterization. Trials of antibiotic prophylaxis in short-term catheterization have mostly shown no benefit. For long-term prophylaxis the frequency with which resistant organisms recommendation to treat only appear, has led to the almost universal symptomatic infection. Although in this situation tissue infection must be expected, most studies in elderly patients or those with neurogenic bladders support the conclusion that the interval between UTIs or pyrexias (which probably reflect bacteraemia) is tolerable when balancing against the cross-infection hazards and difficulty of treating resistant pathogens. Outside the urinary tract, prophylaxis relates particularly to two areas; the protection of operation sites and of implant prostheses from circulating bacteria originating in the urinary tract as a result of catheterization. Again, in assessing whether antibiotic prophylaxis could be worthwhile the difficulty lies in the lack of data as to how often operation fields and prostheses are contaminated in this way. In many operations the patient will already be adequately covered by antibiotic prophylaxis for the operation itself, but, for example, should patients undergoing clean operations receive prophylaxis if they are catheterized? Platt et aL4 have published suggestive evidence that antibiotic prophylaxis in hernia and breast surgery is beneficial; catheterization could be expected to increase the risk in these forms of surgery. In orthopaedic surgery, for example, Nelson’ found seven deep wound infections in 358 patients; three infected patients had the same organisms in their urine before surgery. It is not stated how many patients without wound infection had positive urine cultures before surgery although it is perhaps unlikely to have been as much as 43 %. There are other similar accounts in the orthopaedic literature and in such reports it must be accepted that the postoperative wound swabs reflect causative organisms rather than surface contamination of the wound from the perineum or urine. Should patients with cardiac, arterial, orthopaedic and other prostheses ? Anecdotal reports show that receive prophylaxis for catheterization infections of them from the urinary tract can happen, but estimates of the incidence and cost-effectiveness of prophylaxis will require multi-centre trials. Long-term catheterization implies long-term prophylaxis in these patients and the overriding problem remains of resistant organisms, which could equally well invade these sites.
Editorial
3
The prospect of long-term antibiotic prophylaxis in catheterized patients, whether for infection in the urinary tract, or more distantly, has a parallel in the prevention of recurrent cystitis. As a speculation, it might be worth testing the adage ‘take care of the urine and the bladder will look after itself in the context of catheterization. Antibiotics excreted through the kidney reach lo- to loo-fold higher concentrations in the urine than in serum. Would antibiotics in very low doses, sufficient to reach only 4- to 8-fold the MIC of infecting organisms in urine, be successful in preventing bacteriuria in the catheterized patient? Nitrofurantoin reaches adequate concentrations only in the urine, but is known to eliminate lower tract urinary infection in catheterized patients. At such low doses the levels of antibiotics outside the urine would possibly be too low to select resistant bacteria and disturb the normal flora of the bowel and elsewhere. Antibiotics appropriate for this approach would be those with good absorption and which do not lead to resistance. In long-term trials6 in non-catheterized patients norfloxacin and nitrofurantoin have been shown to prevent recurrent UT1 and to have a low incidence of resistant bacteria in the gut and urine. Would they perform equally well in low doses in catheterized patients? P. J. Sanderson
Department of Microbiology Edgware General Hospital Edgware Middlesex HA8 OAD References
1. Schaeffer antimicrobial
AJ, Story KO, Johnson SM. Effect of silver oxide/trichloroisocyanuric urinary drainage system on catheter associated bacteriuria. J Ural
acid 1988;
139: 69-73. 2. Kunin CM, McCormack RC. Prevention of catheter induced urinary tract infections by sterile closed drainage. N Engl J Med 1966; 1155-l 161. 3. Cohen A. A microbiological comparison of a povidoneiodine lubricating gel and a control as catheter lubricants. J Hasp Infect 1985; 6 (Suppl): 155-161. 4. Platt R, Zaleznik DF, Hopkins CC et al. Perioperative antibiotic prophylaxis for herniorrhaphy and breast surgery. N Engl J Med 1990; 322: 153-l 60. 5. Nelson CL, Green TG, Porter RA, Warren RD. One day versus seven days of preventive antibiotic therapy in orthopaedic surgery. Clin Orthop 1983; 176: 258-263. 6. Brumfit W, Smith GW, Hamilton Miller J. Norfloxacin versus macrodantin for the prophylaxis of recurrent urinary tract infection in women. Rev Infect Dis 1989; 11 (Suppl.): 1338.
of Hospital
Infection
(1991) 18, l-3
EDITORIAL
Prophylaxis
for catheter related infection
urinary
tract
Much has been published on the prevention of catheter related urinary infection, yet the subject still provokes thought, research and speculation. In this issue, Hustinx et al. (p. 45) show that the concurrent use of appropriate antibiotics within the 48 hours before catheter removal reduced the risk of bacteriuria five-fold. This result, taking as an end point bacteriuria as such, without assessing clinical outcomes, confirms previous work’ and is not unexpected because of the high concentrations of these antibiotics in urine. It also highlights a recurring problem in the analysis of reports of methods to prevent catheter induced urinary tract infections (UTIs), which so often fail to describe what proportions of patients concurrently received antibiotics. As Hustinx et al. point out, in Kunin & McCormack’s2 trial of closed sterile drainage 84% of their patients received antimicrobials at some stage, and the relative contributions of antimicrobials and closed drainage are consequently less clear. In the survey of Hustinx et al. only 27% of the cases of bacteriuria were accompanied by pyuria. Thus, in most of their patients, only bacteriuria occurred following short-term catheterization. Bacteriuria plus pyuria usually indicates bacterial infection of the tissues of the urinary tract. Bacteria limited to the urine are not causing bladder infection and are not in contact with the blood stream and presumably the danger of bacteriuria by itself, as a cause of infection at distant sites, is less than when there is local tissue invasion. How often and how quickly do the bacteria introduced by the catheter actually invade the tissues of the urinary tract? Could bacteriuria simply reflect urethral organisms pushed into the bladder by the catheter and immediately washed out in the urine sample? Mechanical irritation of the urethra and bladder mucosae by the catheter can also result in pyuria; thus, a further marker along the route of the pathological consequences of catheterization is the development of symptoms of UTI, which distinguish mechanical irritation from bacterial infection. The occurrence of bacteriuria following catheterization seems inevitable with time. The number of bacteria introduced by the catheter even in normal subjects,3 and the speed with which bacteriuria is established, demonstrate the powerful effect of the catheter. This is reflected in the long and unsuccessful history of attempts to prevent catheter induced urinary infection. Most preventative methods involving local disinfection and catheter related techniques have failed in routine use or are not yet practical. 0195-6701/91/050001+03
SO3.00/0
Q 1991 The Hospital
1
lnfectmn
So&t)
2
Editorial
Is it time to consider antibiotic prophylaxis for the problem, as Hustinx et al. suggest? In favour is the demonstrated fact that antibiotics can overcome of bacterial the powerful effect of the catheter; against is the problem resistance and the lack of data as to how often local tissue invasion and distant infection at sites outside the urinary tract actually occur. In the urinary tract bacteriuria by itself seems not to be damaging and usually disappears when the catheter is removed. Asymptomatic bacteriuria is common in elderly females and increases with age in males. It is repeated requiring in patients continuously present frequently catheterization or long-term catheterization. Trials of antibiotic prophylaxis in short-term catheterization have mostly shown no benefit. For long-term prophylaxis the frequency with which resistant organisms recommendation to treat only appear, has led to the almost universal symptomatic infection. Although in this situation tissue infection must be expected, most studies in elderly patients or those with neurogenic bladders support the conclusion that the interval between UTIs or pyrexias (which probably reflect bacteraemia) is tolerable when balancing against the cross-infection hazards and difficulty of treating resistant pathogens. Outside the urinary tract, prophylaxis relates particularly to two areas; the protection of operation sites and of implant prostheses from circulating bacteria originating in the urinary tract as a result of catheterization. Again, in assessing whether antibiotic prophylaxis could be worthwhile the difficulty lies in the lack of data as to how often operation fields and prostheses are contaminated in this way. In many operations the patient will already be adequately covered by antibiotic prophylaxis for the operation itself, but, for example, should patients undergoing clean operations receive prophylaxis if they are catheterized? Platt et aL4 have published suggestive evidence that antibiotic prophylaxis in hernia and breast surgery is beneficial; catheterization could be expected to increase the risk in these forms of surgery. In orthopaedic surgery, for example, Nelson’ found seven deep wound infections in 358 patients; three infected patients had the same organisms in their urine before surgery. It is not stated how many patients without wound infection had positive urine cultures before surgery although it is perhaps unlikely to have been as much as 43 %. There are other similar accounts in the orthopaedic literature and in such reports it must be accepted that the postoperative wound swabs reflect causative organisms rather than surface contamination of the wound from the perineum or urine. Should patients with cardiac, arterial, orthopaedic and other prostheses ? Anecdotal reports show that receive prophylaxis for catheterization infections of them from the urinary tract can happen, but estimates of the incidence and cost-effectiveness of prophylaxis will require multi-centre trials. Long-term catheterization implies long-term prophylaxis in these patients and the overriding problem remains of resistant organisms, which could equally well invade these sites.
Editorial
3
The prospect of long-term antibiotic prophylaxis in catheterized patients, whether for infection in the urinary tract, or more distantly, has a parallel in the prevention of recurrent cystitis. As a speculation, it might be worth testing the adage ‘take care of the urine and the bladder will look after itself in the context of catheterization. Antibiotics excreted through the kidney reach lo- to loo-fold higher concentrations in the urine than in serum. Would antibiotics in very low doses, sufficient to reach only 4- to 8-fold the MIC of infecting organisms in urine, be successful in preventing bacteriuria in the catheterized patient? Nitrofurantoin reaches adequate concentrations only in the urine, but is known to eliminate lower tract urinary infection in catheterized patients. At such low doses the levels of antibiotics outside the urine would possibly be too low to select resistant bacteria and disturb the normal flora of the bowel and elsewhere. Antibiotics appropriate for this approach would be those with good absorption and which do not lead to resistance. In long-term trials6 in non-catheterized patients norfloxacin and nitrofurantoin have been shown to prevent recurrent UT1 and to have a low incidence of resistant bacteria in the gut and urine. Would they perform equally well in low doses in catheterized patients? P. J. Sanderson
Department of Microbiology Edgware General Hospital Edgware Middlesex HA8 OAD References
1. Schaeffer antimicrobial
AJ, Story KO, Johnson SM. Effect of silver oxide/trichloroisocyanuric urinary drainage system on catheter associated bacteriuria. J Ural
acid 1988;
139: 69-73. 2. Kunin CM, McCormack RC. Prevention of catheter induced urinary tract infections by sterile closed drainage. N Engl J Med 1966; 1155-l 161. 3. Cohen A. A microbiological comparison of a povidoneiodine lubricating gel and a control as catheter lubricants. J Hasp Infect 1985; 6 (Suppl): 155-161. 4. Platt R, Zaleznik DF, Hopkins CC et al. Perioperative antibiotic prophylaxis for herniorrhaphy and breast surgery. N Engl J Med 1990; 322: 153-l 60. 5. Nelson CL, Green TG, Porter RA, Warren RD. One day versus seven days of preventive antibiotic therapy in orthopaedic surgery. Clin Orthop 1983; 176: 258-263. 6. Brumfit W, Smith GW, Hamilton Miller J. Norfloxacin versus macrodantin for the prophylaxis of recurrent urinary tract infection in women. Rev Infect Dis 1989; 11 (Suppl.): 1338.
