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Serratia Marcescens is a human pathogenic species of Serratia. It is sometimes linked to disease in humans.  The disease is commonly known as either Serratia plymuthica, Serratia liquefaciens, Serratia rubidaea, Serratia odorifera, or Serratia fonticola.

Serratia Marcescens can be deadly in humans as documented in 1996 when the Center for Disease Control and Prevention (CDC) investigated the deaths of infants at the Baystate Medical Center in Springfield, MA. The Medical Center contacted the CDC when it discovered 32 infants infected with some form of the disease. Of the 32 infants infected, 2 babies died and others remained sick for an extended period of time. Infants are especially susceptible to invasive bacterial infections because their immune systems are unable to fully protect them.

The CDC determined the deadly bacteria was introduced to the neonatal intensive care unit of the medical center in 1994, probably transmitted by a healthcare worker or an infant patient.

In January of 1995 healthcare workers started carrying their own bottles of hand washing soap – individual 4 oz bottles. Many times the bottles were left near sinks, inverted so the opening was contacting the sink – like many people do with shampoo bottles. Investigators found the deadly Serratia Marcescens bacteria in cultures from 16 of the 52 soap bottles and the pathogen was discovered in cultures on 1 of the 15 sinks. The investigation uncovered that water was allowed to pool in and around the sink long enough for the bacteria to grow.

The Serratia Marcescens was allowed to survive in small pools of water at the sinks, and would have entered the soap bottles if the lids were not securely closed. The pathogen could then colonize the soap bottle. Tests of unopened soap bottles showed no sign of S. Marcescens.

Serratia Marcescens in a petri dishAnother very similar case occurred in United Arab Emirates in 2008, when 2 infants died from Serratia Marcenscens while in the Premature and Newborn Department of state-owned Al Wasl Hospital. Overcrowding and poor hospital staff training is believed to be the cause for not identifying the symptoms and treating the patients before it was too late.

The mother of one of the dead infants requested to move its twin brother to another hospital for treatment but was denied. Her story is very painful.

What is Serratia Marcescens: its discovery and history.
Weeping mother of infant killed by serratia marcenscensIn 1819, a Venetian pharmacist known as Bartolomeo Bizio, identified the bacterium and gave it the name Serratia Marcescens. Bizio dubbed it Serratia in honor of Italian physicist Serrati, the steamboat inventor, and Bizio decided on Marcescens (from the Latin word which means decaying) given that the bloody pigment was known to decay rapidly.

From 1906 up to the 1950s, doctors used Serratia Marcescens as biological marker for researching the propagation of microorganisms because the bacterium was usually considered innocuous. There are recorded incidents of the U.S. military testing Serratia Marcescens on U.S. citizens in the 1950s. After the military disclosed its testing, hospitals pointed to increased pneumonia diagnosis in the subsequent weeks and months, and some deaths occurred as a result. But after the 1960s, Serratia Marcescens was clearly identified as an harmful human pathogen and as pointed out in this article, it can be deadly.

Infant infected with Serratia MarcescensMany variations relating to Serratia marcescens are capable of generating a coloring known as prodigiosin, which varies in color from deep red to light red or pinkish, based on the age of the pathogen. It can develop in soil, water, bathroom facilities or in starchy food, where the pigmented bacterium are sometimes wrongly taken for blood spots. Several cases of infants infected with serratia marcescens were somewhat easier to diagnose due to the distinctive coloring.

Serratia Marcescens Symptoms

Here are some symptoms linked with Serratia Marcescens:

  • Chills
  • Fever
  • Sepsis (pus-forming bacteria in the body)
  • Infection (by pathogenic microorganisms)
  • Nausea
  • Vomiting
  • Shock
  • Convulsions
  • Bacteremia (bacteria in the blood)
  • Urinary tract infections
  • Empyema (collection of pus in a body cavity – especially around lungs and heart)
  • Lymphadenitis (inflammation of a lymphatic gland)
  • Endocarditis (inflammation of the endocardium – membrane around heart)
  • Meningitis Peritonitis (inflammation, pain and tenderness in the abdomen, vomiting, constipation, and moderate fever)
  • Respiratory distress
  • Death

Serratia Marcescens Treatment

When diagnosed with this bacteria, people ask “What is Serratia Marcescens” and are then relieved when it is treated with antibiotic therapy including ampicillin and macrolides. Most varieties of the bacterium are susceptible to amikacin, but there have been reports of resistance to gentamicin and tobramycin. However, we must not forget that S. Marcescens is deadly when not diagnosed and treated properly.

Comprehensive testing is required as new strains of the bacterium can be resistant to common treatment.

Home therapy may be an option when the patient is stable enough to be released from hospital.

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