What infections can Serratia marcescens cause?

Infections Caused by Serratia marcescens

Serratia marcescens is an opportunistic pathogen that causes a wide range of infections including bloodstream infections, pneumonia, urinary tract infections, endocarditis, skin and soft tissue infections, and ocular infections.

Common Infections Caused by S. marcescens

Respiratory Tract Infections

• S. marcescens is a significant cause of nosocomial pneumonia, particularly in ventilated patients and intensive care settings 1
• It ranks among the common gram-negative pathogens causing hospital-acquired pneumonia, following Pseudomonas aeruginosa, Klebsiella species, and Enterobacter species 1

Bloodstream Infections

• S. marcescens frequently causes bacteremia and bloodstream infections, especially in immunocompromised patients 2, 3
• These infections can progress to endotoxin shock and multiple organ failure due to its gram-negative nature 3
• Bloodstream infections have a high mortality rate, with studies showing attributable mortality rates of up to 60% in neonates 4

Endocarditis

• Though rare, S. marcescens can cause infective endocarditis with high mortality (47.2%) 5
• The mitral valve is most commonly affected, followed by the aortic valve 5
• Endocarditis caused by S. marcescens is associated with intravenous drug use and has higher rates of heart failure and embolic phenomena compared to other gram-negative bacterial endocarditis 5
• Cardiac surgery combined with prolonged antibiotic therapy is often necessary for treatment 6

Ocular Infections

• S. marcescens can cause keratitis and conjunctivitis, particularly in healthcare settings 2
• It is listed as a causative agent of endophthalmitis 1

Urinary Tract Infections

• S. marcescens is a recognized cause of urinary tract infections 7, 2
• The FDA has approved ciprofloxacin for treating urinary tract infections caused by S. marcescens 7

Skin and Soft Tissue Infections

• S. marcescens can cause wound infections and necrotizing soft tissue infections 6, 2
• Bone and joint infections can also be caused by this organism 7

Neonatal Infections

• S. marcescens is particularly problematic in neonatal intensive care units (NICUs) 2, 4
• In neonates, it can cause sepsis, pneumonia, meningitis, and gastrointestinal infections 2
• Outbreaks in NICUs have been reported with significant morbidity and mortality 4

Transmission and Risk Factors

• Healthcare-associated transmission often occurs via contaminated hands of healthcare workers 2, 4
• Environmental sources include contaminated water, sinks, antiseptics, and medical equipment 2, 3
• Risk factors include immunocompromise, critical illness, invasive procedures, and prolonged hospitalization 2
• Colonization of the respiratory and gastrointestinal tracts can lead to subsequent infection 2

Antimicrobial Resistance and Treatment

• S. marcescens has intrinsic resistance to several antibiotic classes and can develop multidrug resistance 2
• It possesses an inducible AmpC β-lactamase that can confer resistance to many β-lactam antibiotics 1
• Plasmid-mediated metallo-β-lactamases (such as IMP-type enzymes) can cause carbapenem resistance 1
• Treatment options include:
  • Extended-spectrum cephalosporins (e.g., ceftriaxone) 6, 8
  • Fluoroquinolones (e.g., ciprofloxacin) for susceptible strains 7
  • Carbapenems for serious infections 6
  • Aminoglycosides, often used in combination therapy 6, 5

Prevention and Control

• Early identification of colonized or infected patients is crucial 2
• Rigorous hand hygiene and contact precautions are essential control measures 2
• Environmental cleaning, particularly of water sources and sinks 2, 4
• Proper management of antiseptics and medical equipment 3
• Surveillance cultures may be useful during outbreaks 4