CAUTI - Catheter Associated Urinary Tract Infection.

U

rinary catheter is a device that is used to treat urinary incontinence by placing it inside the bladder through the urethra. The most common catheter used is the Foley’s catheter.

The diameter of the foley’s catheter is called as “FRENCH” unit.

Originally it is an open system where it is drained into an empty container. But closed systems are also present where the urine flows through the catheter into the closed bag.

The urinary tract infection caused by catheterization is called as CAUTI or Catheter Associated Urinary tract infection. It is caused in a hospital setting and is one of the most common infections occurring in the hospital after the patient is admitted. Hence it is one of the NOSICOMIAL infections.

It is defined as –

In patients with indwelling catheters (uretheral or suprapubic) or intermittent catheterization with –

1.    Presence of symptoms or signs compatible with UTI with no other identified source of infection.

2.    10³  colony forming units (CFU)/ml of 1 bacterial species in a single catheter urine specimen or in a midstream voided urine specimen from a patient whose catheter has been removed in previous 48 hours.

Pathogenesis –

Source of infection is either Intraluminal or Extraluminal.

a.     Intraluminal – break in closed drainage or contamination of collection bag urine.

b.    Extraluminal – Early at insertion or late by capillary reaction.

Source of micro-organisms is from Endogenous routes or Exogenous routes.

a.     Endogenous routes – Meatal, rectal, or vaginal colonization.

b.    Exogenous routes – Contaminated hands, of health-care workers

The percentage of organisms that infect while CAUTI –

Mechanism of CAUTI based on the prospective study of 1497 newly catheterized patients who had 235 new onset infection [courtesy of Tambyah, Halvorson and Maki. Mayo clinic Proc. 1999 Feb; 74(2): 131 – 6].

Mechanism of CAUTI	Gram positive cocci (n = 44)	Yeasts (n = 34)	Gram negative Bacilli (n = 37)	Overall (n = 114)
Extraluminal	79%	69%	54%	66%
Intraluminal	21%	31%	46%	34%

Formation of biofilms by urinary pathogens is common on catheter surfaces and collecting systems. This makes the bacteria resistant to antimicrobials.

Risk Factors –

1.    Prolonged catherization (>6 days)

2.    Female gender

3.    Catheter insertion outside operating room.

4.    Other active sites of infection.

5.    Diabetes.

6.    Malnutrition.

7.    Azotemia (creatinine level>2.0 mg/dL)

[ bold points indicative of the majority of the risk factors contributing towards the infection].

Clinical Features –

1.    Fever

2.    Chills

3.    Cloudy urine

4.    Bloody urine

5.    Strong urine odour

6.    Unexpected fatigue

7.    Vomiting

8.    Pressure, pain or discomfort in the lower back or stomach

9.    Urine leakage around the catheter

Diagnosis –

1.    Gold standard is urine culture.

2.    Dipstick and other things are not reliable as number of organisms is controversial.

Preventive measures –

1.    Insert catheters when conditions are appropriate.

2.    Maintain a closed system.

3.    Maintain urine flow.

4.    Hand hygiene and standard precautions to be followed.

5.    Use of aseptic methods for insertion of catheters.

6.    Do not use the catheters for prolonged duration, remove before 5-6 days and insert a new one.

7.    Use precoated catheters like nitrofurantoin coated catheters, or polymyxin coated catheters (but success rate of polymyxin coated catheter is low and thus was discarded).

8.    Use the catheter size that is appropriate to the patient’s urethra (e.g. if a patient require a catheter of size 14 Fr, use a 14 Fr catheter and avoid its contamination).

Conditions when catheterization is required –

1.    Acute urinary retention or obstruction.

2.    For accurate measurements in critically ill patients.

3.    End of the life comfort.

4.    Prolonged immobilization.

5.    Selected surgical procedures like in urological procedures.

6.    Healing of open sacral or perineal wounds.

Points to keep in mind for CAUTI –

1.    When to label a person as diagnosed with CAUTI? Only if the doctor diagnoses the patient as CAUTI and prescribes antibiotics within 48 hours or the first positive urine sample indicates the presence of bacterial.

2.     Are all patients who are catheter bound included in CAUTI? No. There are exceptions. Patients catheterized for operations or surgical procedures or those who are catheterized in the ER (emergency Room) are included.

3.    A patient undergoing a treatment of UTI and has a catheter is categorized as CAUTI? NO, Patients are excluded from CAUTI treatment when they are undergoing the UTI treatment (at the time catheter was inserted).

4.    Following catheter removal how many days does the patient requires follow up? 3 days

5.    If a patient has intermittent catheterization is, he a patient of CAUTI?  No, not until there are no signs of fever.