Catheter-associated urinary tract infection (CAUTI)

This might be the single most important investigation to perform in a patient with possible CAUTI.

• If the Foley catheter is dysfunctional, this creates a much higher risk of pyelonephritis, septic shock, and obstructive renal failure. Urinary obstruction is an emergent problem that requires immediate attention (e.g., replacement of the foley catheter).
• If the Foley catheter is draining urine normally, this makes the likelihood of an invasive bacterial infection much less likely .

how to evaluate the Foley catheter

• Ideally: POCUS to exclude a distended bladder:
  • The finding of a distended bladder indicates dysfunction of the Foley catheter . This indicates a true risk of pyelonephritis, septic shock, and obstructive renal failure.
  • A non-distended bladder indicates normal function of the Foley catheter.

  Bacteriuria in the presence of a well-functioning catheter is probably somewhat analogous to a drained abscess, in which drainage prevents additional infectious complications – Trautner BW and Morgan DJ (32324234)

  #3) replace Foley and check UA/Cx

  

  ⚠️ The Foley catheter should be replaced prior to obtaining a urine culture. Otherwise, the culture may be contaminated by bacterial growth within the foley catheter (which doesn't represent an invasive bacterial infection). This is recommended by the Infectious Diseases Society of America. (37902340)

  #4) evaluate urinalysis & culture data

  

  pyuria

  • Definition of pyuria?
    • Pyuria is generally defined as >10 WBC per high-power field . (31532742)
    • However, studies have used cutoffs varying between ~5-25 WBC per high-power field. (10724053, 35580716)

    urine culture

    • ⚠️ Over time, most urinary catheters will become colonized with bacteria (asymptomatic bacteriuria). This occurs at a rate of 3-10% per day, so nearly all patients catheterized for a month will have bacteriuria. (30241712) Consequently, the presence of bacteria doesn't necessarily indicate CAUTI.
    • >100,000 colony-forming units per ml of a uropathological bacteria is generally considered positive.

    other tests

    procalcitonin

    • The role of procalcitonin in UTI requires further research. However, it does appear that procalcitonin >0.5 is sensitive for the detection of urinary tract infection with bacteremia. (27979420, 25944771)
    • For patients in whom the clinical suspicion is low for CAUTI (e.g., no neutropenia, obstruction, or urologic surgery), a procalcitonin

    treatment of CAUTI

    when to start antibiotics?

    • It is unclear exactly when antibiotics should be started during the diagnostic evaluation for CAUTI.
      • For patients with clinical signs of septic shock or neutropenic fever, antibiotic initiation should not be delayed.
      • For patients with an isolated fever, antibiotics should generally be withheld pending additional investigation (fever isn't an indication for antibiotics!).

      initial antibiotic selection

      causative bacteria

      • Epidemiological studies of CAUTI show that most infections are caused by gram-negative bacilli:
        • E. coli may be most common (~25%).
        • Pseudomonas (~10-20%).
        • Klebsiella pneumoniae/oxytoca (~10%). (31532742)

        how broad does initial coverage need to be?

        • This is unclear.
        • If the patient is stable (e.g., febrile, but not shocked), then it's unnecessary to empirically cover every possible bacteria.
          • Note that CAUTI would only rarely lead to clinical shock – so if the patient is in septic shock then alternative sources should be aggressively pursued.

          initial coverage for stable patients

          • Consider any available data:
            • Urinalysis with positive nitrites suggests an enterobacteriaceae.
            • Urine cultures may reveal preliminary data (e.g., gram-negative rods).

            💡 Culture and sensitivity information should almost always be available within 48-72 hours. This should allow for narrowing and focusing of antibiotic therapy.

            antibiotic duration

            • Available studies suggest that a 5-7 day course is sufficient. (26402541, 37592966, 31532742)
            • For patients with neutropenia, pregnancy, or urological surgery longer courses could be considered.

            prevention

            avoid or limit Foley catheter placement

            • Review the need for a Foley catheter daily (similarly to ongoing review for a central line).

            alternatives to bladder catheterization?

            • These include a condom catheter for men or an external female collection device for women (e.g., PureWick).
            • Although intuitively these devices might seem safer, they are not supported by robust data among ICU patients.

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            questions & discussion

            To keep this page small and fast, questions & discussion about this post can be found on another page here.

            • Urinalysis should not be checked simply due to cloudy or odorous urine (Class A recommendation from Infectious Diseases Society of America). This probably represents colonization of the Foley bag, not invasive infection.
            • Be careful about blaming fever and sepsis on CAUTI. CAUTI is a rare cause of severe illness, so it's probable that something else is going on (e.g., ventilator-associated pneumonia or line infection). Prematurely anchoring on the diagnosis of CAUTI could cause another focus of infection to be overlooked.
            • Lower urinary tract symptoms (e.g., frequency, dysuria) may be due to irritation of the bladder by the catheter itself, rendering them nonspecific and unhelpful.

            Guide to emoji hyperlinks

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            References

            • 10724054 Tambyah PA, Maki DG. Catheter-associated urinary tract infection is rarely symptomatic: a prospective study of 1,497 catheterized patients. Arch Intern Med. 2000;160(5):678-682. doi:10.1001/archinte.160.5.678 [PubMed]
            • 20175247 Hooton TM, Bradley SF, Cardenas DD, et al. Diagnosis, prevention, and treatment of catheter-associated urinary tract infection in adults: 2009 International Clinical Practice Guidelines from the Infectious Diseases Society of America. Clin Infect Dis. 2010;50(5):625-663. doi:10.1086/650482 [PubMed]
            • 23878765 Cunha BA. Clinical approach to fever in the neurosurgical intensive care unit: Focus on drug fever. Surg Neurol Int. 2013;4(Suppl 5):S318-S322. Published 2013 May 6. doi:10.4103/2152-7806.111432 [PubMed]
            • 24479059 Al Montasir A, Al Mustaque A. Purple urine bag syndrome. J Family Med Prim Care. 2013;2(1):104-105. doi:10.4103/2249-4863.109970 [PubMed]
            • 25944771 Julián-Jiménez A, Gutiérrez-Martín P, Lizcano-Lizcano A, López-Guerrero MA, Barroso-Manso Á, Heredero-Gálvez E. Usefulness of procalcitonin and C-reactive protein for predicting bacteremia in urinary tract infections in the emergency department. Actas Urol Esp. 2015;39(8):502-510. doi:10.1016/j.acuro.2015.03.003 [PubMed]
            • 27979420 Yan ST, Sun LC, Jia HB, Gao W, Yang JP, Zhang GQ. Procalcitonin levels in bloodstream infections caused by different sources and species of bacteria. Am J Emerg Med. 2017;35(4):579-583. doi:10.1016/j.ajem.2016.12.017 [PubMed]
            • 29910547 Saran S, Rao NS, Azim A. Diagnosing Catheter-associated Urinary Tract Infection in Critically Ill Patients: Do the Guidelines Help?. Indian J Crit Care Med. 2018;22(5):357-360. doi:10.4103/ijccm.IJCCM_434_17 [PubMed]
            • 30241712 Shuman EK, Chenoweth CE. Urinary Catheter-Associated Infections. Infect Dis Clin North Am. 2018;32(4):885-897. doi:10.1016/j.idc.2018.07.002 [PubMed]
            • 31532742 Clarke K, Hall CL, Wiley Z, Tejedor SC, Kim JS, Reif L, Witt L, Jacob JT. Catheter-Associated Urinary Tract Infections in Adults: Diagnosis, Treatment, and Prevention. J Hosp Med. 2020 Sep;15(9):552-556. doi: 10.12788/jhm.3292 [PubMed]
            • 32324234 Trautner BW, Morgan DJ. Imprecision Medicine: Challenges in Diagnosis, Treatment, and Measuring Quality for Catheter-Associated Urinary Tract Infection. Clin Infect Dis. 2020 Dec 3;71(9):e520-e522. doi: 10.1093/cid/ciaa467 [PubMed]
            • 37902340 O'Grady NP, Alexander E, Alhazzani W, Alshamsi F, Cuellar-Rodriguez J, Jefferson BK, Kalil AC, Pastores SM, Patel R, van Duin D, Weber DJ, Deresinski S. Society of Critical Care Medicine and the Infectious Diseases Society of America Guidelines for Evaluating New Fever in Adult Patients in the ICU. Crit Care Med. 2023 Nov 1;51(11):1570-1586. doi: 10.1097/CCM.0000000000006022 [PubMed]