Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
11 Cards in this Set
- Front
- Back
|
Morphology and gram nature |
Short rods, gram negative. Also non - motile. |
|
|
Cultural characteristics |
They are aerobes and facultative anareobes. Colorless colonies on MacConkey agar, what does it indicates..I hope you know :p S.sonnei does forms pink colonies on over incubation, it is a late lactose fermenter |
|
|
Biochemical reactions |
Positive:Methyl red test, nitrate test, catalase, glucose fermentation without gas production, mannitol fermentation is crucial for classification. Negative: citrate utilization, lactose and sucrose not fermented, VP test negative. |
|
|
Antigens |
Antigenic structure simpler as compared to Salmonellae. Somatic'O' antigens. K antigens. Fimbrial antigens. |
|
|
Types 1. S.dysentriae |
Mannitol non fermenters, indole and catalase negative. Forms shiga toxin-causes neurotoxicity, enterotoxicity and cytotoxicity. |
|
|
S.flexneri |
has six serotypes from 1-6. Serotype 6 is always indole negative. has two more complex antigens- X and Y. |
|
|
S.boydii |
Resembles flexneri biochemically but not antigenically. Has 15 serotypes. |
|
|
Sh.sonnei |
Only type that ferments lactose. Indole negative. Occurs in two forms-phase 1 and phase 2. causes mildest form of bacillary dysentery |
|
|
Pathogenicity |
Infect epithelial cells of large intestine. Mechanism is enteroinvasive and they penetrate into lamina propria. Causes capillary thrombosis,leading to necrosis of epithelial causing transverse superficial ulcers. Bacteremia may also occur in severe cases. |
|
|
Complications |
Most often seen in infection due to S.dysentriae. Arthritis, toxic neuritis, conjunctivitis, parotitis. Children : intussusception (coiling and entangling of the loo[s of the colon) |
|
|
Treatment |
Oral rehydration. Nalidixic acid. Norfloxacin. mnemonic - Nano Other fluoroquinones. |
