Catheter Associated Urinary Tract Infection (CAUTI)

Catheter Associated Urinary Tract Infection (CAUTI)

Definition

A Catheter-Associated Urinary Tract Infection (CAUTI) is a UTI occurring in a patient with:

An indwelling urinary catheter in place for >2 calendar days
OR
Catheter removed within the previous 48 hours

with:

Compatible symptoms/signs of UTI
AND
Significant bacteriuria.

Catheter-Associated Asymptomatic Bacteriuria (CA-ASB)

Bacteria in urine without symptoms.

Diagnostic threshold-≥10⁵ CFU/mL in catheter urine
WITHOUT symptoms.

Important Point- Do NOT treat routinely.

Exceptions:

Pregnancy
Before invasive urologic procedures
Selected neutropenic/transplant situations.

Duration and Risk of CAUTI

Duration	Risk
1 day	3–7% bacteriuria risk
1 week	10–30%
1 month	Nearly universal bacteriuria

Pathogenesis of CAUTI

Core Mechanism: Biofilm Formation

1. Catheter insertion-Introduces bacteria into bladder.Perineum → catheter → bladder → upper urinary tract

2.Organisms adhere to:Catheter surface,Uroepithelium.

3. Biofilm formation

Bacteria produce:Extracellular polysaccharide matrix.

Biofilm:Protects bacteria from:

Antibiotics
Host immunity

4. Ascending infection

Organisms ascend:Extraluminally OR Intraluminally.

5. Bladder colonization → pyelonephritis → bacteremia

Routes of Infection

Route	Mechanism
Extraluminal	Along catheter outside surface
Intraluminal	Through contaminated drainage system
Hematogenous	Rare

Biofilm Organisms

Common biofilm-formers:

Escherichia coli
Klebsiella pneumoniae
Pseudomonas aeruginosa
Proteus mirabilis
Enterococcus faecalis
Candida albicans

Etiology

A. Gram-Negative Bacilli (Most Common)

Organism	Important Features
E. coli	Most common overall
Klebsiella	ESBL producer
Proteus	Urease producer; stones
Pseudomonas	ICU/MDR pathogen
Enterobacter	Nosocomial resistant pathogen
Acinetobacter	Severe ICU infection

B. Gram-Positive Organisms

Organism	Notes
Enterococcus	Common in prolonged catheterization
Staphylococcus aureus	May suggest bacteremia
CoNS	Usually colonization

C. Fungal

Organism	Notes
Candida spp.	Common in ICU/diabetes/antibiotic exposure

Risk Factors

Catheter Factors

Duration of catheterization (MOST important)
Breaks in sterile system
Frequent manipulation
Large catheter size
Improper insertion technique

Patient Factors

Female sex
Diabetes mellitus
CKD
Immunosuppression
Malnutrition
Advanced age
Neurogenic bladder
Urinary obstruction

Hospital Factors

ICU stay
Broad-spectrum antibiotics
Prolonged hospitalization
Poor infection control

Clinical Features

A. Lower UTI Features

Fever
Suprapubic pain
Dysuria (if catheter removed)
Urgency/frequency
Flank discomfort
Delirium in elderly

B. Pyelonephritis Features

High-grade fever
Chills
CVA tenderness
Nausea/vomiting
Sepsis.

Cloudy urine ≠ CAUTI

Foul-smelling urine ≠ CAUTI

Pyuria alone ≠ CAUTI

These commonly indicate:

Colonization
Asymptomatic bacteriuria.

Diagnostic Criteria

CDC/NHSN Definition (Simplified)

Patient with:

Indwelling catheter >2 days
AND
≥1 symptom:

Fever
Suprapubic tenderness
CVA tenderness
Urgency/frequency/dysuria after removal
AND

Urine culture:

≥10⁵ CFU/mL (≥10³ CFU/mL by IDSA)
≤2 organisms.

Diagnostic Evaluation

1. Clinical Assessment

Assess:

Symptoms
Sepsis
Obstruction
Alternate fever source.

2. Urinalysis(Urine Analysis supports diagnosis but DOES NOT confirm CAUTI.)

Findings:

Pyuria
Leukocyte esterase
Nitrites
WBC casts (upper tract).

BUT:
⚠ Pyuria common even without infection.

Nitrite Test

Positive nitrite suggests:

Enterobacterales

E. coli
Klebsiella
Proteus

Negative nitrite DOES NOT exclude CAUTI.

3. Urine Culture

How to collect- Never from drainage bag.

Collect from:

Sampling port
AFTER:
Disinfecting port
Clamping briefly.

4. Replace Catheter Before Culture

If catheter present >2 weeks:
Replace catheter first.

Reason:

Removes biofilm
Improves culture accuracy
Helps treatment response.

5. Blood Cultures

Indications:

Fever
Sepsis
ICU patient
Suspected bacteremia.
Immunocompromised patients

6. Imaging

Not routine in uncomplicated CAUTI

Indications:

Persistent fever
Obstruction
Stones
Abscess
Fungus ball
Emphysematous pyelonephritis.

Imaging Modalities

Modality	Use
USG	Hydronephrosis
CT KUB	Stones/abscess
Contrast CT	Complicated pyelonephritis

Differential Diagnosis

Asymptomatic bacteriuria
Noninfectious fever
Drug fever
Pneumonia
CLABSI
C. difficile
Prostatitis
Vaginitis.

Management of CAUTI

PRINCIPLES

Confirm true infection
Remove/replace catheter
Obtain cultures
Start appropriate antibiotics
Control source.

Step 1: Catheter Management

MOST IMPORTANT NON-ANTIBIOTIC STEP

Remove catheter if no longer needed.

Replace catheter if:

Present >2 weeks
Obstructed
Encrusted
Biofilm suspected.

Step 2: Empirical Antibiotic Therapy

Drug/Class	Dose & Duration	Remarks
STABLE / NON-SEPTIC CAUTI
Nitrofurantoin	100 mg PO BD for 5–7 days	Lower CAUTI/cystitis only; good for E. coli, Enterococcus; avoid in pyelonephritis, sepsis, CrCl <30 mL/min
TMP–SMX (Trimethoprim–Sulfamethoxazole)	160 / 800 mg PO BD 160/800 mg PO BD for 7–14 days	Gram-negative CAUTI; avoid if high local resistance, hyperkalemia, severe renal dysfunction
Amoxicillin–Clavulanate	625 mg PO TDS or 1 g PO BDfor 7–14 days	Mild–moderate CAUTI; some Enterococcus coverage; poor ESBL coverage
Ciprofloxacin	500–750 mg PO BD or 400 mg IV BD for 5–14 days	Excellent urinary and tissue penetration; Pseudomonas coverage; avoid unnecessary use due to resistance/QT/tendon toxicity
Levofloxacin	750 mg PO/IV OD for 5 days	Complicated UTI/CAUTI with good response; broad gram-negative coverage
MODERATE TO SEVERE CAUTI
Ceftriaxone	1 − 2 g IV OD 1−2 g IV OD for 7–14 days	Hospitalized stable CAUTI; no Pseudomonas or ESBL coverage
Piperacillin–Tazobactam	4.5 g IV every 6 hours 4.5 g IV every 6 hours for 7–14 days	Severe/ICU CAUTI; covers Pseudomonas, Enterococcus, anaerobes; extended infusion preferred
Cefepime	2 g IV every 8–12 hr for 7–14 days	Severe gram-negative/Pseudomonas CAUTI; monitor for neurotoxicity in CKD
MANAGEMENT OF MDR/XDR CAUTI-ESBL Organisms
Meropenem	1 g IV every 8 hours 1 g IV every 8 hours for 7–14 days	Severe gram-negative/Pseudomonas CAUTI; monitor for neurotoxicity in CKD
Imipenem–Cilastatin	500 mg IV every 6 hr	ESBL severe CAUTI; higher seizure risk
Ertapenem	1 g IV OD	ESBL CAUTI without Pseudomonas risk

Gentamicin	5–7 mg/kg IV OD	Severe gram-negative CAUTI; combination therapy; nephrotoxicity/ototoxicity risk
Amikacin	15–20 mg/kg IV OD	MDR resistant gram-negative CAUTI
Ampicillin	1–2 g IV every 4–6 hr	Ampicillin-sensitive Enterococcal CAUTI
Amoxicillin	500 mg PO TDS	Oral step-down for Enterococcal CAUTI
Vancomycin	15 − 20 mg/kg IV every 8-12 hours 15−20 mg/kg IV every 8-12 hours	MRSA CAUTI; monitor AUC/MIC or troughs
VRE (Vancomycin Resistant Enterococcus)
Linezolid	600 mg PO/IV BD	VRE or MRSA CAUTI; thrombocytopenia and serotonin syndrome risk
Daptomycin	6–10 mg/kg IV OD	VRE/MRSA CAUTI; monitor CPK

Fluconazole	200–400 mg PO/IV OD for 14 days	Symptomatic Candida CAUTI; preferred for Candida albicans
Amphotericin B deoxycholate	0.3–0.6 mg/kg/day IV	Fluconazole-resistant Candida; nephrotoxic
Flucytosine	25 mg/kg PO QID	Combination therapy for resistant Candida
Fosfomycin	3 g PO every 48–72 hr × 3 doses	MDR lower CAUTI/ESBL cystitis; not for pyelonephritis/bacteremia
CRE (Carbapenem Resistant Enterobacterales)
Ceftazidime–Avibactam	2.5 g IV every 8 hr	CRE/XDR gram-negative CAUTI
Meropenem–Vaborbactam	4 g IV every 8 hr	Carbapenem-resistant Enterobacterales
Imipenem–Relebactam	1.25 g IV every 6 hr	Resistant Pseudomonas/CRE infections
Cefiderocol	2 g IV every 8 hr	Salvage therapy for highly resistant gram-negative CAUTI

Duration Summary

Clinical Situation	Recommended Duration
Rapid clinical response	5–7 days
Delayed response	10–14 days
Pyelonephritis	10–14 days
Bacteremic CAUTI	10–14 days
Candida CAUTI	14 days
Women <65 yrs after catheter removal	3 days

Adjust all according to:

Renal function
CRRT
Dialysis.

Short-Course Therapy

Possible in:

Non-severe infection
Rapid clinical improvement
Catheter removed.

Candida CAUTI

Usually Colonization

Do NOT treat asymptomatic candiduria routinely.

Treat only if:

Symptomatic
Neutropenia
Urologic procedure planned
Fungus ball(Obstruction)
Candidemia risk.
Renal transplant

Common Candida Species

Species	Important Features
Candida albicans	Most common
Candida glabrata	Azole resistance common
Candida tropicalis	More invasive in neutropenia
Candida parapsilosis	Biofilm formation
Candida krusei	Intrinsic fluconazole resistance
Candida auris	MDR nosocomial pathogen

Ophthalmologic Examination

Needed if candidemia present because of risk of: Candida endophthalmitis

Treatment

Catheter removal alone may clear candiduria.

Drug	Dose
Fluconazole	200–400 mg PO/IV daily 14 days
Amphotericin B 0.3–0.6 mg/kg/day IV	Resistant Candida-C. krusei,C. glabrata

Prevention of CAUTI

“Avoid unnecessary catheterization.”

Indications for Urinary Catheter

Appropriate Indications

Acute urinary retention
Accurate urine output in shock/ICU
Perioperative selected surgeries
Neurogenic bladder
Comfort in terminal care.

CAUTI Prevention Bundle

Measure	Importance
Hand hygiene	Essential
Aseptic insertion	Mandatory
Closed drainage system	Critical
Keep bag below bladder	Prevent reflux
Avoid breaks in system	Prevent contamination
Daily review of need	MOST effective
Early removal	Strongest preventive strategy

Antimicrobial Catheters

Examples:

Silver alloy
Nitrofurazone-coated.

May reduce short-term bacteriuria but:

Limited long-term benefit
Cost concerns.

Intermittent Catheterization vs Foley

Intermittent catheterization: Lower infection risk than chronic Foley.

Complications of CAUTI

Local Complications

Cystitis
Pyelonephritis
Prostatitis
Epididymitis
Perinephric abscess

Systemic Complications

Gram-negative bacteremia
Septic shock
MODS.

Mechanical Complications

Urethral trauma
Stricture
Bladder spasms
Hematuria
Stone formation.