Causes of Serratia marcescens Urinary Tract Infections
Serratia marcescens urinary tract infections (UTIs) are primarily associated with urinary catheterization, urologic procedures, and healthcare settings, with indwelling catheters being the most significant risk factor.
Primary Risk Factors
Catheter-Associated Infections
- Indwelling urinary catheters are the leading cause of S. marcescens UTIs 1, 2
- The duration of catheterization directly correlates with infection risk 1
- S. marcescens can form biofilms on catheter surfaces, making eradication difficult
- Improper catheter care and handling increases transmission risk
Healthcare-Associated Factors
- Hospital environment contamination, particularly in urology units 3, 4
- Contaminated equipment such as:
- Cross-contamination between patients via healthcare workers' hands 4
- Extended hospital stays, especially in urology wards 5
Patient-Specific Risk Factors
- Recent urologic surgery or procedures 5
- Advanced age 2
- Underlying chronic or debilitating medical conditions 2
- Immunocompromised status 6
- Previous antibiotic treatment, especially broad-spectrum antibiotics 2
- Incomplete bladder emptying or urinary retention 6
- Urinary tract abnormalities or obstruction 6
Microbiological Characteristics
S. marcescens has several characteristics that facilitate UTIs:
- Ability to develop multidrug resistance, particularly to aminoglycosides 5
- Capacity to form biofilms on medical devices
- Persistence in hospital environments
- Can survive in disinfectants if inadequately prepared
Transmission Patterns
- Patient-to-patient transmission via healthcare workers' hands 4
- Reservoir-to-patient transmission from contaminated equipment 4
- Chronically infected patients serve as reservoirs during multiple hospitalizations 5
Clinical Significance
While often considered a contaminant in catheterized patients without symptoms, S. marcescens can cause:
- Symptomatic UTIs
- Bacteremia with potential for severe complications 2
- Rarely, endocarditis (primarily in intravenous drug users) 7
- Sepsis with high mortality in vulnerable patients 2
Prevention Strategies
- Minimize duration of catheterization 1
- Use hydrophilic coated catheters 1
- Proper disinfection of urinary measurement equipment 4
- Strict adherence to hand hygiene protocols
- Prompt removal or replacement of catheters in infected patients 1
- Avoid prophylactic antimicrobials for catheterization 1
Common Pitfalls
- Dismissing S. marcescens as a contaminant in catheterized patients with risk factors 2
- Failure to identify and address the underlying source (contaminated equipment, etc.)
- Inadequate duration of therapy, especially when complications are present 6
- Not recognizing the potential for multidrug resistance 5
S. marcescens UTIs require thorough evaluation for underlying structural or functional abnormalities and appropriate antimicrobial therapy based on susceptibility testing, with particular attention to removing or replacing catheters when present.