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3 Cards in this Set
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Proteus
Proteus mirabilis Proteus vulgaris
Produce enzyme phenylalanine deaminase which converts phenylalanine to phenylpyruvic acid
Swarming on agar plate Motile Non lactose fermenters on MacConkey agar produce colorless colonies XLD, HEK, SS- Lactose negative, May have black centers due to H2S
Fish pungent odour of colonies
Part of commensal in human intestine
Show pleomorphism
Identification Glucose - acids and gas Sucrose negative for Proteus mirabilis but positive for Proteus vulgaris H2S positive
TSI- K/A ,G, H2S for mirabilis A/A,G, H2S for vulgaris
Deaminase positive Urease positive - Christensen medium Indole- negative for mirabilis but positive for vulgaris Ornithine positive for mirabilis but negative for vulgaris
Motility - positive Swarms over BPA and obliterate other colonies Can use CNA( colistin nalidixic acid)/ PEA(phenylethyl alcohol) plates to grow gram positive and inhibit Gram -ve
Proteus mirabilis vs Proteus vulgaris Sucrose -ve. +ve Indole -ve. +Ve Ornithine +ve. -ve TSI K/A, G, H2S. A/A, G H2S Deaminase+. + Urease +. +
Naming of O and H antigens
H antigens/flagella antigen Grow on agar as thin films resembling film of breath on glass
O antigen Thin film not observed when grown on media
Clinical features P mirabilis more common, urinary and wounds, occasional septicemia, pneumonia, nosocomial outbreak
Pathogenesis
Struvite Stony bladder Produce urease-breaks down urea to Ammonia that damage renal epithelium and make urine alkaline-deposition of phosphate-renal calculi
Basis of Weil-Felix reaction Somatic antigen non motile Proteus strains OX2, OX19 from vulgaris, OXK from mirabilis cross react with antigen of rickettsiae species
Proteus antigens are used to detect heterophile antibodies in sera of patients suffering rickettsial infections
Laboratory diagnosis
Specimen according to type of infections Direct microscopy- gram positive pleomorphic bacilli
Pleomorphism- are gram negative coccobacilli occasionally bacilli and infilamentous forms
Odour- fishy smell
Swarming- ability to spread on surface of solid media
Swarming patterns- continuous and discontinuous swarming
Problem- tends to swarm and overgrow other bacteria
Mechanism of swarming- at colony margin, sparsely flagellated short vegetative cells, multinucleated densely flagellated, elongated cells-swarm cells
Swarm cells migrates to sarounding uninoculated
Transition from vegetative cells to swarm cells occur as a result of intracellular and extracellular signals
Method's of preventing swarming
Increase agar concentration to 6% Incorporation of alcohol, boric acid, chloral hydrate, sodium azide sulfonamides, surface active agent's Doesn't occur on MacConkey or CLED agar
Organisms swarming P mirabilis P vulgaris Serratia marcescens Vibrio parahemolyticus Clostridium tetani
Biochemical property
Both mirabilis and vulgaris Urease positive Citrate variable TSI alkaline/acid ,gas present h2s present MR positive but VP negative
Differences Indole positive in vulgaris but negative for mirabilis Ornithine decarboxylase negative for vulgaris but positive for mirabilis
Typing of Proteus Bacteriocin typing Bacteriophage typing Ribotyping
Denes phenomenon
If swarming of two Proteus isolates inoculated next to each other Merge completely- identical strains Remain separated- both strains are different
Treatment Susceptible to most antibiotics
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Providencia
Providencia rettgeri Providencia stuartii
Grey moist on blood agar Non lactose fermenters on MacConkey agar
XLD, HEK SS- Lactose negative without black centers due to no H2S
Identification Glucose -acid and small amount of gas H2s negative TSI K/A Deaminase (TDA,PDA) Positive Urease variable Ornithine negative from Morganella Indole positive
Clinical significance Urinary and wounds Nosocomial
Treatment Susceptible to most antibiotics
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Morganella
Morganella morganii Grey moist appearance on blood agar. Non lactose fermenters on MacConkey XLD HEK SS- Lactose negative, no black centers due to no H2S
Identification
Glucose - acids and small amount of gas H2S negative TSI K/A small amount of gas no H2S Deaminase positive Urease positive Indole positive Ornithine positive different from Providencia
Clinical significance
Urinary and wounds especially debilitated hospital patients
Treatment Susceptible to most antibiotics |
Shigella vs. Morganella Deaminase -ve. +ve Urease. -ve. +Ve TSI. K/A. K/A
Providencia vs Morganella vs Proteus Deaminase+. +. + Urease. +/-. +. +/- Ornithine. -. +. +/- H2S. -. -. + |
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Treatment of class Proteeae Often multi drug resistance Intrinsic resistance Nitrofurantoin, tigecycline, polymyxin Produce beta lactamases: extended spectrum beta lactamases and AmpC beta lactamases Effective drugs Aminoglycosides, fourth generation cephalosporin, carbapenems, fosfomycin Mirabilis more susceptible to antibiotics |
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