Serratia is a genus of Gram-negative,facultatively anaerobic, rod-shaped bacteriaof the Enterobacteriaceae family.•This is a Gram negative rod that thrives inmoist environments.•It frequently contaminates solutions andhospital equipment and the humanreservoirs are the urinary and respiratorytracts as well as the gastrointestinal tract ofchildren.
The genus is named after SerafinoSerrati, an Italian physicist.
The most common species in the genus, S. marcescens, is normally the onlypathogen and usuallycauses nosocomial infections.However, rare strains of S. plymuthica,S. liquefaciens, S. rubidaea, andS. odoriferae have caused diseasesthrough infection.
* Members of this genus produce characteristicred pigment, prodigiosin , and can bedistinguished from other members of the familyEnterobacteriaceae by its unique production ofthree enzymes: DNase, lipase, and gelatinase.* In the hospital, Serratia species tend tocolonize the respiratory and urinary tracts, ratherthan the gastrointestinal tract, in adults.
•Serratia infection is responsible for about 2% ofnosocomial infections of the bloodstream, lowerrespiratory tract, urinary tract, surgical wounds,and skin and soft tissues in adult patients.•Outbreaks of S. marcescens meningitis, woundinfections, and arthritis have occurred in pediatricwards.•Serratia infection has caused endocarditis andosteomyelitis in people addicted to heroin.•Cases of Serratia arthritis have been reported inoutpatients receiving intra-articular injections.
•S. marcescens was once thought to be a non-pathogenicbacteria.•Because of the red pigment it produces, it was widelyused to trace bacterial transmission and to study settlingand drifting of bacteria in air currents.•In 1950 the US Navy conducted a secret experimentcalled “Operation Sea-Spray” to study wind currents thatmight carry biological weapons.•They filled balloons with S. marcescens and burst themover San Francisco.•Shortly thereafter, doctors in the area noted a drasticincrease in pneumonia and urinary tract infections.
•Some strains of S. marcescens are capable ofproducing a pigment called prodigiosin, whichranges in color from dark red to pale pink, dependingon the age of the colonies.•S. marcescens has a predilection for growth onstarchy foodstuffs, where the pigmented colonies areeasily mistaken for drops of blood.
•In 1819, Bartolomeo Bizio, a pharmacist fromPadua, Italy, discovered and named S.marcescens when he identified the bacterium as thecause of a miraculous bloody discoloration in acornmeal mush called polenta.•Bizio named Serratia in honor of an Italian physicistnamed Serrati, who invented the steamboat, andBizio chose marcescens (from the Latin word fordecaying) because the bloody pigment was found todeteriorate quickly.
•Since 1906, physicians have usedS marcescens as a biological marker for studyingthe transmission of microorganisms because, untilthe 1950s, this bacterium was generally considereda harmless saprophyte.•Only since the 1960s has S marcescens beenrecognized as an opportunistic pathogen inhumans.•Derivatives of prodigiosin have recently beenfound to have immunosuppressive properties andantitumor activity in vivo.
InternationalThe yearly incidence of Serratia bacteremia is1.03 per 100,000 population, with 47% ofepisodes having their onset in the community.The prevalence of Serratia species as a cause ofnosocomial infections is diminishing, but thesebacteria are still able to cause hospital outbreaks,especially in intensive care units.
Significance in endoscopyIf more evidence is required ofthe pivotal role ofadequate mechanical cleaning in endoscopereprocessing then it is provided by Serratiamarcescens.Several outbreaks of S. marcescens infection havebeen tracked to bronchoscopic transmission. In anoutbreak involving three fatalities, the instrumenthad been inadequately cleaned but then subjectedto a full ethylene oxide sterilising process,underlining the fact that any attempts at sterilisationor disinfection are likely to be ineffective in thepresence of inadequate cleaning.
Mortality/MorbidityIn a population-based studyof Serratia bacteremia, the 7-day and 6-monthmortality rates were 5% and 37%, respectively.Serratia meningitis and Serratia endocarditiscarry a high mortality rate.Serratia species cause less than 6% of cases ofhospital-acquired bacterial pneumonia.S marcescens causes 11% of burn-relatedsurgical wound infections.
DiseaseSignificant cause of health care associatedpulmonary, urinary, and surgical site infections.Mode of transmissionThe organism is usually transmitted from personto person via the nahds of HCWs or fromenvironmental reservoirs to patients.
SexMost (68%) episodes of Serratia bacteremiaoccur in males.AgeOutbreaks of Serratia infection occur inneonates and infants. In adults,mostSerratia infections are isolated, butoccasional nosocomial outbreaks occur.