Gram Negative Rods – Flashcards
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Unlock answers| Gram neg rods are divided into: |
1. enterics 2. nonfermenters 3. coccobacillary Gram neg rods |
| The largest group is the ... |
| ... ENTERICS. |
| Characteristics of enterics: |
1. gram neg 2. nonsporeforming 3. facultative anaerobic rods 4. ferment glucose 5. produce acid + gas 6. can grow in the intestinal tracts of warm-blooded mammals |
| The 3 groups of intestinal pathogens of enterics are: |
1. Salmonella 2. Shigella 3. Vibrio |
| Salmonella is an ... |
| ENTERIC |
| Shigella is an ... |
| ENTERIC |
| Vibrio is an ... |
| ENTERIC |
| The 4 diseases they cause are all manifested in the gastrointestinal disorder ... |
| DIARRHEA |
| Salmonella typhi causes... |
| TYPHOID FEVER! |
| The duration of typhoid fever is ... |
| several weeks. |
| How many stages does typhoid fever have? |
| 2 |
| The first stage of typhoid fever lasts ... |
| 1 - 2 weeks |
| Symptoms of the 1st stage of typhoid fever: |
- low-grade fever - constipation |
| In the 1st stage of typhoid fever, organisms can only be cultured from ... |
| the blood |
| In the 2nd stage of typhoid fever, organisms can only be cultured from ... |
| the stool |
| Symptoms of the 2nd stage of typhoid fever: |
- high fever - liquid, bloody stools |
| Necrosis = |
| tissue damage |
| Salmonella typhimurium causes ... |
| Gastroenteritis (food poisoning) |
| Result of gastroenteritis... |
diarrhea! (not as bad as typhoid fever) |
| Shigella causes ... |
| bacillary dysentery |
| Dysentery is ... |
| ... diarrhea containing white blood cells/pus |
| Shigella grows and multiplies in ... |
| the large intestine. |
| Vibrio cholorae causes... |
cholera! (endemic to Southeast Asia and India) |
| Vibrio produces a toxin that ... |
... radically upsets the ability of inestinal cells to contain water => HYPERSECRETION OF WATER => diarrhea => dehydration, acidosis, shock, death :( |
| All Gram neg organisms are ... |
PATHOGENIC (produce a fever) |
| Pathogenisity in due, in part, to ... |
| LIPOPOLYSACCHARIDES |
| Escherichia causes: |
1. #1 cause of UTIs 2. Septicemia (infection of blood stream) 3. Spinal meningitis in newborns 4. Abdominal and wound infections |
| Salmonella causes: |
1. Typhoid fever 2. Gastroenteritis 3. Osteomyelitis (infection of the bone) |
| Shigella causes: |
| 1. Bacillary dysentery |
| Citrobacter causes: |
| Abdominal and wound infections |
| Klebsiella causes: |
1. Severe enteritis in children 2. Preumonia and upper respiratory infections 3. UTIs of nosocomial origin |
| Serratia causes: |
| Thought to be innocuous, now implicated in pulmonary infections and septicemia. |
| Enterobacter causes: |
| Abdominal and would infections |
| Proteus causes: |
1. #1 cause of UTIs in males 2. abdominal and wound infections |
| All enterics are defined as being ... |
| OXIDASE NEGATIVE |
| Vibrio is oxidase... |
| positive! |
| The 6 tests discussed in lab are... |
1. MACCONKEY AGAR 2. TSI (Triple Sugar Iron Agar) 3. UREASE 4. INDOLE 5. CITRATE 6. OXIDASE TEST - Q-tip |
MACCONKEY AGAR: Polymicrobial = |
| numeous different organisms |
The most common Gram negative selective medium is ... |
| MACCONKEY AGAR |
MACCONKEY AGAR: Selective due to ... |
... BILE SALTS + CRYSTAL VIOLET |
MACCONKEY AGAR: Differential due to... |
| ph indicator, NETRAL RED. |
MACCONKEY AGAR: The plate tests for ... |
| lactose fermentation |
MACCONKEY AGAR: The plate indicates that an organism is a ... |
| GRAM NEG ROD |
Color of MACCONKEY AGAR |
| Pale pink |
MACCONKEY AGAR: Interpretation of results: positive = |
RED colonies Lactose fermenters |
MACCONKEY AGAR: Interpretation of results: negative = |
COLORLESS colonies non-lactose fermenters |
MACCONKEY AGAR: Interpretation of results: GROWTH = |
| gram neg rod |
| All pathogens are ... |
lactose negative *except Salmonella and Shigella |
| Color of TSI... |
| Red agar |
| TSI contains: |
1. 3 sugars 2. Sodium thiosulfate 3. Phenol red |
| TSI: Sodium thiosulfate detects organism that can produce... |
| H2S |
TSI: Phenol red: Alkaline = ... Acid = ... |
... RED (K) ... YELLOW (A) |
TSI: If an organism can only ferment glucose... |
- whole tube => initially yellow (because of the acid produced)
- once glucose is used up => fermentation stops
- respiration continues in slant => pH will rise
- in slant, acids are oxidized
- slant will turn back to red (alkaline)
- the butt will remain yellow (anaerobic) |
TSI: If an organism can only ferment glucose, the ratio is... |
| K/A |
TSI: If an organism can ferment glucose and lactose... |
- the whole tube => yellow
- glucose fermented 1st, then others
- tube remains yellow bc of acid |
TSI: If an organism can ferment glucose and lactose, the rate is ... |
| A/A |
TSI: If an organism can't ferment glucose... |
| ... it is not enteric! |
TSI: If an organism can't ferment glucose, the result will be... |
- pH won't fall - tube will remain red |
TSI: If an organism can't ferment glucose, it is called a ... |
| NON-FERMENTER! |
TSI: If an organism can't ferment glucose, the rate is ... |
K/K (nu sugar fermented) |
TSI: Gas production is detected by ... |
bubbles in the agar (many, few or even none) |
Which organisms produce hydrogen sulfide? |
Salmonella and Shigella (+ others) |
| Organisms produce H2S by ... |
| reducing thiosulfate! |
| The production of H2S is detected by ... |
FERROUS SULFATE (which produces a black precipitate, FeS) ; Black color will mask the color of the agar! |
| UREASE: Several organisms, but neither of the pathogens,;can split ... |
UREA -; AMMONIA due to the presence of urease. |
| N |
UREASE: Interpretation of results: ; |
+ - hot pink neg - light pink |
| INDOLE: Tryptophanase cleaves ...; |
| tryptophan -; indole! |
| UREASE: Presence of indole can be detected by the addition of ... |
| Kovac's Reagent |
| UREASE: Kovac's reagent reacts with indole to produce... |
| a cherry red color! |
| A few of the enterics can use citrate as the sole source of ... |
| CARBON and ENERGY for growth |
| CITRATE: Ammonium phosphate does what? |
release of ammonium ions increase in pH |
| CITRATE: pH indicator is ... |
Brom Thymol Blue (changes from green to blue above pH 7.6) |
| Which tests are part of the IMViC reactions used in water analysis? |
1. citrate 2. indole |
| IMViC stands for ... |
| Indole Methyl red Voges-Proskauer i Citrate |
IMViC: Methyl Red and Voges-Proskauer are rests of ... |
| fermentation products. |
| NONFERMENTERS are strict ... |
| aerobes! |
| NONFERMENTERS: Eg... |
- Pseudomonas - Alcaligenes - Acinetobacter - Moraxella |
| NONFERMENTERS: are environmental organisms. T/F |
| TRUE |
NONFERMENTERS: Pseudomonas aeruginosa causes: |
- UTIs - septicemia - upper and lower resp tract inf - wound and burn inf |
| What is the difference between Acinetobacter and Pseudomonas? |
| Acinetobacter is not as resistant to antibiotics as Pseudomonas is! |
| The pigment produced by Pseudomonas aeruginosa is called ... |
PYOCYANIN! (green, smells like grapes) |
| Characteristics of the Pyocyanin ... |
- diffusible - water soluble - green |
| Characteristic that separates Pseudomonas from other gram neg rods is that it is ... |
| OXIDASE POZ |
| The oxidase reaction tests for ... |
| ... the presence of cytochrome C! |
| Interpretation for Oxidase test: |
- poz: dark purple in less ;10 s - neg: no color change/purple in ;20 - questionable: purple in 10 - 20 s |
