proteus by Dr j.jayaprakash Cuddalore.pptx

Proteus

1. PROTEUS Presented By Dr. J. Jayaprakash M.Sc., Ph. D., Head Of the Department, Department of Microbiology St. Joseph’s College of Arts and Science Cuddalore-01

2. TRIBE: PROTEEAE Proteus mirabilis and Proteus vulgaris Proteus is a group of bacilli that constitute the tribe Proteeae , which are non-lactose fermenters and are not considered as coliform bacilli. However , they are also normal intestinal commensals and opportunistic pathogens like coliforms. The name Proteus refers to their pleomorphism , after the Greek god Proteus who could assume any shape. The tribe Proteeae is classified into three genera: Proteus , Morganella and Providencia. Most of them, except for some Providencia strains, produce a powerful enzyme, urease, which rapidly hydrolyses urea to ammonia and carbon dioxide.

3. PPA Reaction A characteristic feature which distinguishes Proteeae from other enterobacteria is the presence, in all members of the tribe, of the enzyme phenyl alanine deaminase which converts phenyl alanine to phenyl pyruvic acid (PPA reaction). All of them , with few exceptions , are Gram-negative , non-capsulated, pleomorphic, motile rods.

4. Proteeae Resistant to K CN D eg ra de tyrosine Fai l to acidify lactose , dulc i tol or malonate D o not form arginine or lysine decarbo x ylase or b eta ga l ac to sidase MR-posi t ive and VP-negative

5. We il -Fe l ix reaction These bacilli posse s s s omatic O and flagellar H antigens, whi c h form the ba s is of Weil-Felix reaction for the diagnosis of few rickettsial infections. This is used as a diagno s tic t es t due to cross-reaction of these antigens (heterophile antigens) with some Rickettsiae. However , this te s t is not widely recommended now. Three non-motil e Proteus strains-OX2 , OX19 and OXK-are used in the agglutination test.

6. Proteus species - saprophytes. The y are found in decomposing animal matter, sewage , manured soil , human and anima feces . The y are frequently present on moist areas (perineal and axil lary regions , and anterior urethra) . The y are opportuni s tic pathogens, often nosocomial , commonly responsible for urinary and septic infections . The genus Proteus contain s two medically importan t species- Pr.mirabilis , which is an important urinary and nosocomial pathogen , and P r. vulgaris which is found much less commonly in human infections. A characteristic putrid odour described as ' fish y' or 'se m i n al' odo ur is produced in cultures .

7. Swarm in g Pr.mirabili s and Pr. v ulgaris swarm on solid culture media. Discrete colonies ar e seen in young cultures but thereafter actively motile cells spread on th e surface of the plate in succes s ive waves to form a thin filmy layer in concentric circles. This poses a problem in the laboratory , when mixed growth is obtained from clinical samples . Several methods have been used to inhibit swarming: namely , increasing the concentration of agar to 6 %, incorporating chloral hydrate (1 :500) , sodium azide (1 : 500) , alcohol (5-6 % ), sulphonamid e, and surface active agents or boric acid ( 1 : 1 000 ) in the medium. Swarming does not occur on MacConkey medium due to the presence of bile. Smooth, colourless colonies are formed on this medium .

8. Tre a t m ent Proteus species are resistant to many of t h e common antibiotics. An exception is Pr.mirab il is whic h is sensitive to ampicillin and cephalosporins . Amikaci n and ciprofloxacin are generally effective in t reatment of infections due to Providencia .

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