Serratia marcescens an emerging pathogen

1. Serratia marcescensan emerging pathogen Dr.T.V.Rao MD Dr.T.V.Rao MD

2. Serratia marcescens • Serratia marcescens is a motile, short rod-shaped, Gram-negative, facultative anaerobe bacterium, classified as an opportunistic pathogen. It was discovered in 1819 by Bartolomeo Bizio in Padua, Italy. Bizio named the genus Serratia in honor of and Italian physicist named Serratia, and chose marcescens for the species name after the Latin word for decay. Serratia marcescens was first thought to be harmless (non-pathogenic). Dr.T.V.Rao MD

3. Gram negative bacillus 7 species S. marcescens most common Motile, often red pigment Environmental water, soil, plants, insects, animals Extracellular enzymes contribute to pathogenicity elastase, lecithinase, caseinase etc. May be antibiotic multi-resistant Serratia species Dr.T.V.Rao MD

4. Serratia marcescens • Serratia marcescens grows at 37°C, but it can grow in temperatures that range from 5–40°C. They grow in pH levels that range from 5 to 9 . Serratia marcescens is well known for the red pigmentation it produces called prodigiosin. Prodigiosin is made up of three pyrrole rings and is not produced at 37°C, but at temperatures below 30°C . • Many pathogenic strains are non pigment producers Dr.T.V.Rao MD

5. Serratia and nosocomial infections • Over the last 40 years, Serratia marcescens has become an important cause of nosocomial infection. There have been many reports concerning the identification, antibiotic susceptibility, pathogenicity, epidemiological investigations and typing of this organism Dr.T.V.Rao MD

6. S. marcescens contaminates • The growth of S. marcescens in the environment has been investigated in relation to water, disinfectants and plastics such as blood bags. Certain extracellular products are unique to S. marcescens. Pigment (prodigiosin) biosynthesis by S. marcescens has been investigated fully since the emergence of the organism as a cause of infection. Dr.T.V.Rao MD

7. Identification of S. marcescens • S. marcescens was defined by Grimont and Grimont as an oxidase-negative gram-negative bacillus producing DNAase. . S. marcescens is unable to ferment arabinose in peptone water, whereas all S. liquefaciens strains are arabinose-positive.. To confirm the identity of S. marcescens, a short series of sugars, including arabinose and raffinose, should be tested in tubes, Dr.T.V.Rao MD

8. Serratia marcescens an emerging pathogen • Serratia marcescens is a species of Gram-negative, rod-shaped bacterium in the family Enterobacteriaceae. A human pathogen, S. marcescens is involved in nosocomial infections, particularly catheter-associated bacteremia, urinary tract infections and wound infections,] and is responsible for 1.4% of nosocomial bacteremia cases in the United States.[3] It is commonly found in the respiratory and urinary tracts of hospitalized adults and in the gastrointestinal system of children. Dr.T.V.Rao MD

9. S. marcescens and biofilms • S. marcescens possessing type 1 fimbriae use biofilms to regulate quorum sensing . Biofilms are formed when S. marcescens aggregate together and attach to a surface . When these microbes aggregate together they can communicate with one another via quorum sensing. Serratia can benefit from biofilms because they are proposed to provide protection against external . Dr.T.V.Rao MD

10. Transmission on hands of staff most important mode of spread Occasional focal environmental source Infection usually occurs in compromised patients: Pneumonia in ventilated patients UTI in catheterised patients Post-operative wound infections Blood stream infection in patients with intravenous access devices Serratia marcescensInfection Issues Dr.T.V.Rao MD

11. Bacteremia / septicemia Meningitis ventriculitis, cysts cell count may be normal mortality 40% Pneumonia Urinary tract infection Soft-tissue infection Overall mortality 14% Serratia marcescensClinical Presentation Dr.T.V.Rao MD

12. Some Serratia are not pigment producers • The red pigment production is not present in all strains but in those that it is present, it can resemble red pigment. Dr.T.V.Rao MD

13. S.Marcescens and R- Factors • S.marcescens contain these R-factors which are a specific types of plasmid carries one or more genes that that confers resistance to different types of antimicrobial agents. The contribution of R-factors to the resistance of Serratia to various drugs has been studied as far back as 1969[23]. This study found that out of 22 multiple resistant strains, 21 were able to transfer some form of their resistance to others. This study also demonstrated that drug resistance was far more prevalent in Serratia than in any other commonly isolated member of the Enterobacteriaceae. Dr.T.V.Rao MD

14. Temperature sensitive R-factors • It was also found that not only did the R-factors mediate drug resistance to the strains that were once susceptible to certain drugs, but it further conferred additional resistance to drugs which the strains were already previously resistant to . Since then, other experiments have concluded that the transfer system of R-factors in Serratia marcescens may be temperature sensitive and more likely to occur between those organisms that are found to be more closely related phylogenetically. Dr.T.V.Rao MD

15. Treating the Serratia infection • Infections caused by S. marcescens may be difficult to treat because of resistance to a variety of antibiotics, including ampicillin and first and second generation cephalosporins . Aminoglycosides have good activity against S. rnarcescens, but resistant strains have-also been reported recently . Dr.T.V.Rao MD

16. Problem of drug resiatnce • While B-lactamase-mediated carbapenem resistance is rare among the Enterobacteriaceae, it has been described recently for clinical isolates of S. marcescens and Enterobacter cloacae. This resistance may arise from two mechanisms: first, high-level production of chromosomal AmpC cephalosporinases combined with substantially decreased outer-membrane permeability and second, the synthesis of /?- lactamases able to hydrolyse carbapenems Dr.T.V.Rao MD

17. Serratia and research on cancer • Recent study suggests that Serratia marcescensost3 produces a novel prodigiosin called MAMPDM ((2,2'-[3-methoxy-1'amyl-5'-methyl-4-(1"-pyrryl)]dipyrrylmethene))that may have an important impact on cancer treatment. This red pigment demonstrated a selective cytotoxic activity in cancer cell lines, but in contrast it revealed a reduced toxicity to non malignant cells. They came to the conclusion that Serratia marcescens may in one time be used as a source to develop an anti-cancer compound Dr.T.V.Rao MD

18. Growing importance of Serratia marcescens • S. marcescens is an opportunistic pathogen causing a plethora of nosocomial infections in humans and some cases have been reported in animals. Many strains have become resistant to a variety of drugs. Future research, should evaluate different measures to prevent outbreaks of Serratia marcescens by evaluating antibiotics and the mode of entry into the bacterium. Pathogenic pathways should be more fully defined to understand how resistant S. marcescens infections may become vulnerable to different treatment methods. Dr.T.V.Rao MD

19. Hand Hygiene and improved health standards will reduce Serratia infections Dr.T.V.Rao MD

20. Programme created by Dr.T.V.Rao MD for Medical and Health Care Professionals in the Developing World • Email • doctortvrao@gmail.com Dr.T.V.Rao MD