Management of Pseudomonas aeruginosa Bacteriuria in Elderly Patients
This elderly patient with Pseudomonas aeruginosa at 10,000-50,000 CFU/mL should NOT be treated with antibiotics unless they have clear localizing urinary symptoms (dysuria, frequency, urgency) or systemic signs of infection (fever >100°F, rigors, hypotension). 1
Critical First Step: Distinguish Asymptomatic Bacteriuria from True UTI
The presence of bacteria in urine alone does not warrant treatment in elderly patients. 1
Asymptomatic bacteriuria occurs in approximately 40% of institutionalized elderly patients and causes neither morbidity nor increased mortality 2, 3
Treatment of asymptomatic bacteriuria only promotes antibiotic resistance without clinical benefit 2
For diagnosis of symptomatic UTI, the patient MUST have recent-onset dysuria PLUS at least one of the following: 4, 2
- Urinary frequency or urgency
- New incontinence
- Systemic signs (fever >100°F, shaking chills, hypotension)
- Costovertebral angle pain/tenderness of recent onset
Urine dipstick tests have only 20-70% specificity in elderly patients, making clinical symptoms paramount for diagnosis 1, 4
Pyuria and positive dipstick results do not indicate need for treatment without accompanying symptoms 2
If Treatment is Warranted: Antibiotic Selection for Pseudomonas aeruginosa
If the patient has true symptomatic UTI, obtain urine culture with susceptibility testing before initiating empiric therapy. 2
First-Line Empiric Options for Pseudomonas UTI:
Levofloxacin 750 mg once daily for 10 days is indicated for complicated UTI caused by Pseudomonas aeruginosa 5
Gentamicin IV (dosed by renal function and weight) is effective against Pseudomonas aeruginosa in serious urinary tract infections 6
- Requires monitoring of renal function and drug levels due to nephrotoxicity risk 6
- Particularly important in elderly with baseline renal impairment
Critical Considerations for Pseudomonas:
- Pseudomonas aeruginosa may develop resistance rapidly during treatment with fluoroquinolones 5
- Culture and susceptibility testing should be performed periodically during therapy to monitor for emerging resistance 5
- For documented Pseudomonas infections, combination therapy with an anti-pseudomonal β-lactam (such as ceftazidime or piperacillin/tazobactam) may be necessary for severe infections 5
Renal Function Assessment is Mandatory
Calculate creatinine clearance using Cockcroft-Gault equation before prescribing any antibiotic, as renal function declines by approximately 40% by age 70. 2
- Assess and optimize hydration status before initiating nephrotoxic therapy 2
- Adjust all antibiotic doses based on calculated creatinine clearance 2
- Avoid coadministration of nephrotoxic drugs with UTI treatment 2
- Recheck renal function in 48-72 hours after starting antibiotics 2
Common Pitfalls to Avoid
- Do not treat based solely on positive urine culture without symptoms - this leads to unnecessary antibiotic exposure and resistance 1, 2, 3
- Do not dismiss atypical presentations - elderly patients may present with confusion, functional decline, or falls rather than classic dysuria 1
- Do not use standard first-line UTI antibiotics (fosfomycin, nitrofurantoin, trimethoprim-sulfamethoxazole) for Pseudomonas, as these organisms are typically resistant 4, 5
- If patient has indwelling catheter - virtually all catheterized patients have bacteriuria; only treat if systemic signs are present, and change the catheter before collecting specimen 2, 7
Monitoring and Follow-up
- Evaluate for clinical response within 48-72 hours of initiating therapy 4
- Adjust treatment based on culture susceptibility results once available 5
- Monitor for drug-related adverse effects, particularly in patients with polypharmacy 1
- Consider that Pseudomonas can invade bladder epithelial cells, potentially complicating treatment response 8