Serratia marcescens: Causes, Symptoms, Diagnosis, and Treatment of the Red-Pigmented Bacterium

Introduction Genus Serratia

The genus Serratia belongs to the family Enterobacteriaceae and consists of Gram-negative, facultatively anaerobic, rod-shaped bacteria. Members of this genus are widely distributed in nature, being found in soil, water, plants, and as opportunistic pathogens in humans. Serratia species are motile due to peritrichous flagella and are capable of producing a characteristic red pigment called prodigiosin (especially in Serratia marcescens). Serrata marcescens is commonly encountered in clinical specimens, especially cases of bacteraemia. Serratia species are motile Gram negative rods. Certain species of serrata marcescens produces red pigmented colonies on agar. Serratia is noted for its vibrant red color, it thrives in wet environments. It’s commonly seen in bathrooms as a red film over tiles and drains.

Medical Importance of Genus Serratia

1. Serratia marcescens:

Serratia marcescens a species of gram-negative, belongs to family Enterobacteriaceae, facultatively anaerobic, rod-shaped bacteria found in soil, water, food, and clinical specimens. It is a prominent opportunistic pathogen for hospitalized patients. Serratia marcescens grows in pH levels that range from 5 to 9. Serratia marcencens is well known for the red pigmentation it produces called prodigiosin. It is involved In hospital-acquired infections, particularly catheter-associated bacteremia, urinary tract infections and wound infections, and responsible for 1.4% of HAI cases in the United States. It is commonly found in the respiratory urinary tracts of hospitalized adults and in the gastrointestinal system of children. Rinsing and drying surfaces after use can also prevent the establishment of the bacterium by removing its food source and making the environment less hospitable.

2. Serratia liquefaciens:

Serratia liquefaciens growth on muller-hinton agar after day of incubation at room temperature. Serratia liquefaciens is a species of Gram-negative bacteria belonging to the genus Serratia. Gram-negative rods of serratia liquefaciens in gram staining of culture.

Virulence factors

Serratia species expresses a range of fimbrial haemagglutinins some strains express cell surface components causing the bacterial to be highly hydrophobic that may be involved in Adhesion to eukaryotic cell surfaces. An iron regulated hemolysin has been described, but the role for this toxin in the pathogenesis of the disease has not been demonstrated. Serratia species also express an enterobactin – mediated highly affinity iron uptake system. Extra cellular enzymes may be responsible for host tissue damage. Toxins resembling E. coli Verocytotoxin and heat labile toxin have been described.  

Pathogenesis and clinical manifestations

Most infections occur in hospital patients; they include infections of the urinary and respiratory tracts, meningitis, wound infections, septicemia and enocarditis. Serratia species can multiply at ambient temperatures in fluids containing minimal nutrients. Out breaks have followed the introduction of the organisms directly into the blood stream in contaminated transfusion fluids. The other Serratia species also occur commonly in natural environment, especially in water. The clinical manifestations of these infections include cellulitis, abscesses, fluctuant nodules, or granulomatous lesions. Skin infections extremely low and are typically observed in immunocompromised patients. Transmission is by direct contact.

Transmission of serratia marcescens

Direct contact, droplets is of S. marcescens have been found growing on catheters, and in supposedly sterile solution. Users of injection drugs.

Haw to diagnoses Serratia marcescens

Isolation and identification lactose fermenting red pigmented colonies on MacConkey or Eosin methylene blue agar and performing different biochemical tests can identify the organisms. 

Treatment serratia marcescens

Since isolates from hospital acquired infections are frequently resistant to multiple antibiotics, the choice of drugs depends on the results of sensitivity testing.

Conclusion

Serratia is a genus of Gram-negative, facultatively anaerobic bacteria within the Enterobacteriaceae family. The most clinically significant species is Serratia marcescens, which is an opportunistic pathogen associated with hospital-acquired infections such as urinary tract infections, pneumonia, wound infections, and septicemia.