Gram Negative Bacteria Flashcards
Edward and Ewing classification of Enterobacteriacea
Escherichiae - E Coli, Shigella
Edwarsielleae - Edwardsidlla
Salmonellae - Salmonella
Citrobecterae - Citrobacter
Klebsielleae - Kleibsiella, Enterobacter, Serratia
Proteae - Proteus, Morganella
Yersinieae - Yersinia
Erwinieae - Erwinia
Gram Negative bacteria features
Non sporing
Aerobic
Peritrichous flagella
Glucose fermentation
Nitrate to Nitrite
Catalase +ve
Oxidase -ve
All Gram negative Bacteria arr motile except
Shigella
Salmonella gallinarum
Salmonella pullorum
All Gram negative organisms are Catalase positive except
Shigella dysenteriae - Catalse -ve
Classification of gram negative organisms on the basis of Lactose fermentation
Lactose fermenter
Non lactose fermenter
Late lactose fermenter
Examples of lactose fermenter
E coli
Kleibsiella
Enterobacter Citrobacter
Examples of Non lactose fermenter
Salmonella
Shigella
Proteus
Yersinia
Example of Late lactose fermenter
Shigella sonnei
Test for Lactose fermentation
MacConkey agar
CLED (Cystein lactose electrolyte deficient)
Eosin methylene blue
MacConkey agar consist of
PLANT
Peptone
Lactose - diff. Media
Agar
Neutral red - Indicator media
Taurocholate (Bile salts) - Selective media
MacConkey agar gives which color
Pretty Pink color
MacConkey agar is combination of
Differential media , indicator media and selective media
Indicator media for CLED
Bromothymol blue
CLED better than MacConkey agar because
It’s less inhibitory
Allow both gram Positive and gram negative to grow
CLED gives which color
Yellow
Eosin methylene blue shows which colonies and color
Blue Blackish colonies with green shin around it
Classification of Ecoli on the basis of Antigen
Somatic O (cell wall)
Capsular K antigen
Flagella H antigen
Toxins secreted by Ecoli
Hemolysin
Enterotoxins - Labile toxin, Stable toxin, Verocytotoxin/Shiga like toxin
Enterotoxin/Labile toxin fragments
Fragment A - increases cAMP
Fragment B - Binds to GM1 ganglioside
Labile in air
Stable toxin features
cGMP
Stable on ground
Mechanism of action of Shiga toxin or shiga like toxin
Decreases 60S ribosomes - decrease protein synthesis
Clinical features of Ecoli
UTI
Diarrhea
Meningitis
Sepsis
Pneumonia
Diarrheal strains of E Coli
EPEC(Enteropathogenic)
ETEC(Enterotoxigenic)
EIEC(Enteroinvasive)
EHEC(Enterohemorrhagic)
EAEC(Enteroaggregatory)
DAEC(Diffuselyadherent)
Enteropathogenic Ecoli causes
Pediatric/Infantile diarrhea (bcz it produces bundle forming pili) - Plasmid coded
Enteropathogenic Ecoli shows which lesion
Shows A/E Lesions (Attachment/Effacement lesion)
Enterotoxigenic Ecoli causes
Traveller’s Diarrhea
Large infectivity dose is needed
Colonisation factor antigen (CFA)