Lesson 10: The Enterobacteriaceae Flashcards
Bacteria found in the Family Enterobacteriaceae (ESSEPY)
Escherichia
Shigella
Salmonella
Enterobacter
Proteus
Yersinia
Enterobacteriaceae are:
Gram-negative
Short rods
Non-sporulating
Facultative anaerobes
True
It is an agar used to isolate and differentiate organisms of Enterobacteriaceae family
MacConkey agar
MacConkey agar differentiates lactose fermenter coliforms from Non-lactose fermenters by what colors?
Lactose fermenter: Pink colored
Non-Lactose fermenter: Pale colored
Lactose Fermenters (CEEK)
Citrobacter
Escherichia
Enterobacter
Klebsiella
Are enterobacteriaceae Cytochrome C oxidase negative or positive?
Cytochrome C oxidase negative (-)
Non-Lactose Fermenters (ShYPS)
Shigella
Yersinia
Proteus
Salmonella
Are enterobacteriaceae catalase positive or negative?
Catalase positive (+)
Non-Lactose Fermenters
Nonmotile and Non-H2S producing
Shigella
Yersinia
Non-Lactose Fermenters
Motile and H2S producing
Proteus
Salmonella
True or False
Pseudomonas and other oxidase positive bacteria reduce NITRATE to NITROGEN GAS
True
True or False
Enteric bacteria usually reduces NITRATE to NITRITE
True
Oxidase positive bacteria (PAVAAFC)
Pseudomonas
Aeromonas
Vibrio
Alcaligenes
Achromobacter
Flavibacterium
Cardiobacterium
Characteristic antigen of Enterobacteriaceae
Enterobacterial Common Antigen
4 Enterobacterial Common Antigens
O: Outer membrane
H: Flagella
K: Capsule
Vi: Capsule of Salmonella
Does enterobacteriaceae produce acid from glucose and have the ability to ferment lactose?
Yes
Biochemical Tests to Identify Enterobacteriaceae family
IMVC Test
Motility Test
Triple Sugar Iron (TSI) Agar Test
Urease Test
It is a test used to determine the ability of bacteria to utilize sodium citrate as a carbon source and inorganic ammonium dihydrogen phosphate (NH4H2PO4) as the sole fixed nitrogen source
Citrate Utilization Test
Citrate medium most commonly used in the citrate utilization test is?
Formula of Simmons
Utilization of exogenous citrate requires the presence of citrate transport proteins known as?
Permeases
Upon uptake by the cell, citrate is cleaved by citrate lyase into?
Oxaloacetate and acetate
Oxaloacetate is metabolized into?
Pyruvate and CO2
Citrate Test: POSITIVE (SPPECKS)
Serratia marcescens
Providencia
Proteus mirabilis
Enterobacter spp.
Citrobacter freundii
Klebsiella pneumoniae
Salmonella (other than Typhi and Parathypi A)
Under alkaline conditions, pyruvate is metabolized to?
Acetate and formate
At pH 7.0 and below, pyruvate is metabolized to?
Acetate + Lactate + CO2
or
Acetoin + CO2
Growth in Citrate Utilization Test results in the bromothymol blue indicator, turning from ______ to ______
Green to Blue
Bromothymol blue pH indicate has a color of what at neutral pH?
Forest green
An increase in medium pH to above 7.6, bromothymol blue changes to ____
blue
Positive result/Color in Citrate Utilization Test
Intense Prussian blue
Citrate Test: VARIABLE (PVV)
Proteus vulgaris
Vibrio cholerae
Vibrio parahaemolyticus
Citrate Test: NEGATIVE (SMESSY)
Shigella spp.
Morganella morganii
Escherichia coli
Salmonella Typhi
Salmonella Paratyphi A
Yersinia enterocolitica
4(p)-dimethylaminobenzaldehyde reacts with indole to produce what colored compound?
Red-colored compound
It is a test used to determine the ability of an organism to split amino acid TRYPTOPHAN
Indole Test
Tryptophan is hydrolyzed by this enzyme to produce 3 possible end products, one of which is Indole.
Tryptophanase
Indole production is detected by what reagents?
Kovac’s or Ehrlich’s reagent
This is found in Kovac’s or Ehrlich’s reagent that reacts with Indole to produce a “Red-colored” compound
4(p)-dimethylaminobenzaldehyde
Two methods used in Indole Test
Conventional Tube Method
Spot Indole Test (detects rapid indole producing organisms)
In the Conventional Tube Method for Indole Test, how much Kovac’s reagent is added to the broth culture?
0.5 mL of Kovac’s reagent
Results of Conventional Tube Method for Indole Test
Positive:
Negative:
Positive: Pink colored ring
Negative: No color change (E.g. Klebsiella pneumoniae)
It is a type of Indole Test used to determine the presence of the enzyme tryptophanase
Spot Indole Test
In the Spot Indole Test, the piece of filter paper is saturated with?
1% para-dimethylaminocinnamaldehyde reagent
In the Spot Indole Test, when tryptophan releases indole and reacts with “cinnamaldehyde”, it produces what color compound?
Blue-green compound
Spot Indole Test Results:
Positive:
Negative:
Positive: Blue Color within 30 seconds
Negative: No color change / Slightly Pink color
Indole: POSITIVE (PEMP)
E. coli
P. vulgaris
M. morganii
Providencia
Klebsiella species: (Indole Test)
Positive:
Negative:
Positive: K. oxytoca
Negative: K. pneumoniae
Citrobacter spp: (Indole Test)
Positive:
Negative:
Positive: C. koseri
Negative: C. freundii
Proteus spp: (Indole Test)
Positive:
Negative:
Positive: P. vulgaris
Negative: p. mirabilis
Indole Positive for Klebsiella, Citrobacter, and Proteus spp. (OKVIP)
klebsiella Oxytoca
citrobacter Koseri
proteus Vulgaris
Indole Positive
3 commonly used agar for Indole Test (SIM, MIU, MIO)
Sulfide-indole-motility medium (SIM)
Motility-indole-urease medium (MIU)
Motility-indole-ornithine medium (MIO)
What is the most accurate way to determine bacterial motility?
Microscopy
This method is a commonly used microscopic technique to check the motility test
Hanging drop method
Non-motile, gram-positive cocci, enterococci (2)
E. faecium
E. faecalis
Motile, gram-positive cocci, enterococci (2)
E. gallinarum
E. casseliflavus/E. flavescens
A test to differentiate:
Vibrio species (gram-negative motile curved rod)
Aeromonas species (gram-negative motile rod)
Distilled water motility test
Aeromonas species will grow on MacConkey agar and sometimes on Thiosulfate-Citrate-Bile Salts-Sucrose agar, producing what colony color?
Yellow colonies
Methyl Red Results:
Positive:
Negative:
Positive: Red after addition of MR, pH at or below 4.4 from fermentation of glucose
Negative: Yellow after addition of MR, pH above 5.1 from the fermentation of glucose
True or False
Vibrio species and Aeromonas species are oxidase positive (+)
True
Result of Distilled Water Motility Test for Vibrio and Aeromonas spp
Vibrio: immobilized on distilled water and motile on peptone water
Aeromonas: motile in both distilled and peptone water
A test that determines whether the microbe performs mixed acids fermentation when supplied glucose
Methyl Red (MR) Test
What color is methyl red above pH 5.1 and at pH 4.4?
above 5.1 = yellow
at 4.4 = red
Methyl Red (MR): POSITIVE (PYCESS)
Proteus spp.
Yersinia spp.
Citrobacter spp.
Escherichia coli
Shigella spp.
Salmonella spp.
In Methyl Red test, does an intermediate ORANGE color between yellow and red indicate a positive test?
No, it does not.
MR Test Positive: E.coli appearance
E. coli = red color appearance after addition of methyl red reagent
MR Test Negative: K. aerogenes appearance
K. aerogenes = lack of color change after addition of methyl red
Methyl Red (MR): Negative (SHEK)
Serratia marcescens
Hafnia spp.
Enterobacter spp.
Klebsiella pneumoniae
It is a test first observed the “RED” color reaction produced by appropriate culture media after treatment with potassium hydroxide. It was later discovered that the active product in the medium formed by bacterial metabolism is acetyl methyl carbinol, a product of the butylene’s glycol pathway
Voges-Proskauer Test
Members of Klebsiella-Enterobacter-Hafnia-Serratia group produce this as the chief end product of glucose metabolism
Acetoin (acetyl methyl carbinol)
In the presence of atmospheric oxygen and 40% potassium hydroxide, acetoin is converted diacetyl, and __________ serves as a catalyst to bring out a RED COMPLEX
alpha-naphthol
Voges-Proskauer Test Result
Positive:
Negative:
Positive: Red color at 15 minutes or more after the addition of the reagents indicating the presence of diacetyl, the oxidation product of acetoin
Negative: Copper like color (over 1 hour)
In Triple Sugar Iron Agar (TSI), what are the 3 sugar present?
Lactose
Sucrose
Glucose
TSI is a semi-solid media which means that?
It has both a slant and a butt
Concentration of Lactose, Sucrose, Glucose in TSI respectively?
10:10:1
or
1% : 1% : 0.1%
TSI is similar to Kligler’s iron agar (KIA) except that?
KIA has only 2 carbohydrates which is glucose and lactose
Interpretation of Triple Sugar Iron Agar Test:
*If lactose is not fermented but a small amount of glucose is
The oxygen-deficient butt: YELLOW
The less acidic slant: RED
Expected results of TSI Agar test:
Alkaline slant/no change in butt (K/NC)
Alkaline slant/Alkaline butt (K/K)
Alkaline slant/Acidic butt (K/A)
Acidic slant/Acidic butt (A/A)
(K/NC) Red/Red = glucose, lactose and sucrose non-fermenter
(K/K) Red/Red = glucose, lactose and sucrose non-fermenter
(K/A) Red/Yellow = glucose fermentation only, gas (+ or -), H2S (+or -)
(A/A) Yellow/Yellow = glucose, lactose and/or sucrose fermenter gas (+ or -), H2S (+ or -).
Phenol red in TSI is what color in acidic and in alkaline conditions?
Acidic: Yellow
Alkaline: Red
In the TSI agar, what is the indicator of acidification?
Phenol red
Interpretation of Triple Sugar Iron Agar Test:
*If lactose (or sucrose) is fermented
A large amount of acid is produced and turns the phenol red indicator YELLOW both in the butt and slant
Interpretation of Triple Sugar Iron Agar Test:
*If neither lactose/sucrose nor glucose is fermented
Both butt and slant: RED
Reaction of the organisms in the TSI: Salmonella, Proteus
Slant:
Butt:
Gas:
H2S:
Slant: Alkaline (K)
Butt: Acid (A)
Gas: Positive (+)
H2S: Positive (+)
Reaction of the organisms in the TSI: Pseudomonas
Slant:
Butt:
Gas:
H2S:
Slant: Alkaline (K)
Butt: Alkaline (K)
Gas: Negative (-)
H2S: Negative (-)
Reaction of the organisms in the TSI: Escherichia, Klebsiella, Enterobacter
Slant:
Butt:
Gas:
H2S:
Slant: Acid (A)
Butt: Acid (A)
Gas: Positive (+)
H2S: Negative (-)
Interpretation of Triple Sugar Iron Agar Test:
*If H2S is produced
Black color of ferrous sulfide is seen
Reaction of the organisms in the TSI: Shigella, Serratia
Slant:
Butt:
Gas:
H2S:
Slant: Alkaline (K)
Butt: Acid (A)
Gas: Negative (-)
H2S: Negative (-)
2 Medium used for Urease Test
Agar:
Broth:
Agar: Christensen’s Urea Agar (CUA)
Broth: Stuart’s Urea Broth (SUB)
What is the indicator used in Urease Test?
Phenol Red
UREASE TEST: Color change
Non-producer of urease enzyme
Slant and Butt remain LIGHT ORANGE
Which organisms in the urease test will hydrolyze urea RAPIDLY?
(within 1 or 6 hours of incubation)(ProProMo)
Proteus spp.
Morganella morganii
Providencia stuartii strains
In the urease test principle, when urease splits urea in the presence of water to release ammonia and carbon dioxide, the ammonia combines with carbon dioxide and water to form ammonium carbonate which turns the medium alkaline, this will turn the indicator phenol red from its original organ yellow color to?
Bright pink
Note: When the medium turns alkaline, phenol red will convert from yellow to PINK
Urease test results in routine diagnostic laboratories are read within how many hours?
Within 24 hours
Which organisms in the urease test will have a DELAYED POSITIVE?
(6 hours of incubation which will be intense during further incubation) (EnKle)
Enterobacter spp.
Klebsiella spp.
Which organisms in the urease test will have a NEGATIVE result?
(Remain a YELLOWISH color)
Escherichia coli.
Humans are most likely to be infected with what strain of E. coli?
E. coli O157:H7
Urease positive organisms (PUNCH)
Proteus
Ureaplasma
Nocardia
Cryptococcus neoformans/Corynebacterium spp.
Helicobacter pylori
Diagnostic utility of Urease Test: Explain
- Proteus spp. and Enterobacteriaceae
- Helicobacter pylori and tissue biopsy material
- Cryptococcus neoformans and Candida albicans
- Urea breath test: Helicobacter pylori
- Proteus spp. which is urease positive is differentiated from Enterobacteriaceae family which are non-lactose fermenting
- Crushed tissue biopsy is placed into urease broth and if it is positive, there is the presence of Helicobacter pylori
- Cryptococcus neoformans is a rapid urease producer while Candida albicans are not
- Presence of Helicobacter pylori based on urease activity, highly sensitive and specific
UREASE TEST: Color change
Urease enzyme producer
Slant changes from LIGHT ORANGE to MAGENTA
Urease positive bacteria (PCCHB)
Proteus
Cryptococcus
Corynebacterium
Helicobacter pylori
Brucella
Who discovered E. coli after isolating it from the feces of newborns?
Theodor Escherich
Where is the primary habitat of E.coli?
Gastrointestinal tract (GIT)
It is the largest group of bacteria living in the intestine
E. coli
E. coli helps with the absorption of what nutrients in the colon?
Vitamin K and other vitamins
Gram stain of E. coli?
Gram-negative bacilli
What is the TYPE of E.coli that is fimbriated and are present in both motile and non-motile strains.
Type 1 (hemagglutinating & mannose-sensitive)
What is the major cell wall antigen of E. coli?
Heat Stable LPS
What antigen of E. coli is:
“Flagellar Antigen”
Heat and alcohol labile (non-resistant)
Monophasic
H antigen
What antigen of E. coli is:
“Somatic Antigen”
Heat stable, resistant to boiling up to 2 hours and 30 mins
Surface of the Outer Membrane
O antigen
What antigen of E. coli is:
“Capsular Antigen”
Heat labile
Acidic polysaccharide antigen present in the envelope
Inhibits “phagocytosis”
K antigen
How can K antigen be removed?
By boiling
What antigen of E. coli is:
“Fimbrial Antigen”
Heat labile (non-resistant)
Present in the Fimbriae
F antigen
Identify if Nutrient Agar, Blood Agar, MacConkey Agar, EMB Agar, m-ENDO Agar, or Liquid Media for E.coli
“Large, circular, low convex”
Grayish, White
Moist
Smooth and Opaque
2 forms: Smooth and Rough form
Nutrient Agar (NA)
What form of E. coli is emulsifiable in saline?
Smooth form
What causes E. coli to have S-R variation?
Repeated subculture
Identify if Nutrient Agar, Blood Agar, MacConkey Agar, EMB Agar, m-ENDO Agar, or Liquid Media for E.coli
“Big, circular”
Gray
Moist
Beta hemolytic
Blood Agar (BA)
Identify if Nutrient Agar, Blood Agar, MacConkey Agar, EMB Agar, m-ENDO Agar, or Liquid Media for E.coli
“Green Metallic Sheen”
Eosin Methylene Blue (EMB) Agar
What type of hemolysis do E. coli form on Blood Agar?
Beta hemolysis
Identify if Nutrient Agar, Blood Agar, MacConkey Agar, EMB Agar, m-ENDO Agar, or Liquid Media for E.coli
“Circular”
Moist, smooth and of entire margin
Flat and Pink colonies
Lactose fermenting colonies
MacConkeye Agar (MAC)
What does CFA mean for E. coli?
Colonization factor antigen
True or False
Most infections of E. coli are endogenous except for neonatal meningitis and gastroenteritis
True
Identify if Nutrient Agar, Blood Agar, MacConkey Agar, EMB Agar, m-ENDO Agar, or Liquid Media for E.coli
“Green Metallic Sheen”
Metabolize lactose with the production of “Aldehyde and Acid”
m-ENDO Agar
Identify the E. coli pathotype (ETEC, EPEC, EHEC, EIEC, EAEC, DAEC)
“common cause of bacterial diarrheal disease”
“acute watery diarrhea in infants and adults”
“Pathogenesis: attachment to intestinal mucosa mediated by fimbrial protein called CFA” and elaboration of heat-stable and heat-labile enterotoxins”
“No person to person contamination”
ETEC (Enterotoxigenic E. coli)
Identify if Nutrient Agar, Blood Agar, MacConkey Agar, EMB Agar, m-ENDO Agar, or Liquid Media for E.coli
“Homogenous turbid growth within 12-18 hours”
Rough (R) form agglutinate spontaneously
Sediment on bottom of test tube
Pellicle formed on the surface (>72 hours)
Heavy deposits are formed which disperses on shaking
Liquid Media
Identify the Biochemical properties of E. coli
IMVC:
Urease:
Motility:
Catalase:
Carbohydrate fermentation:
IMVC: Indole and Methyl Red Positive
IMVC: Voges-Proskauer and Citrate Negative
Urease: Negative (-)
Motility: Positive (+)
Catalase: Negative (-)
Carbohydrate fermentation: Positive (+)
Identify the E. coli pathotype (ETEC, EPEC, EHEC, EIEC, EAEC, DAEC)
“Frequently causes infantile diarrhea and occasionally causes sporadic diarrhea in adults”
“non-toxigenic and non-invasive”
“Person to person spread is seen”
“Attachment to intestinal mucosa is through cup-like projections called pedestals”
Enteropathogenic E. coli (EPEC)
2 Classes of Enterotoxins produced by ETEC
Heat-stable toxins (STa and STb)
Heat-labile toxins (LT-I and LT-II)
What heat-stable toxin of ETEC is associated with human disease?
STa
What are the 2 groups of E. coli that cause enteric disease?
Enteropathogenic E. coli (EPEC)
Shiga toxin-producing E. coli (STEC)
Cluster of virulence genes of EPEC and STEC are located on a chromosomal pathogenicity island called?
Locus of enterocyte effacement (LEE)
These are produced on the intestinal epithelium coded by LEE gene which leads to the DISRUPTION of brush border epithelium causing increased secretion and watery diarrhea
A/E Lesions (Attaching and Effacing lesions)
Identify the E. coli pathotype (ETEC, EPEC, EHEC, EIEC, EAEC, DAEC)
“These are heterogenous collection of strains characterized by their autoagglutination in a ‘stacked-brick’ arrangement over the epithelium of the small intestine and in the colon”
“These are one of the few bacteria associated with Chronic Diarrhea and growth retardation in children”
Enteroaggregative E. coli (EAEC)
Most strains of EAEC are ___ untypeable but ___ typeable
O = untypeable
H = typeable
True or False
For EHEC, ingestion of FEWER than 100 bacteria can produce disease and spread person-to-person?
True
EAEC adheres to what cells that form a “stacked-brick” fashion?
HEP-2 cells (Human epidermal cells)
What are the other names of Enterohemorrhagic E. coli?
Verocytotoxin-producing E. coli (VTEC)
Shiga toxin-producing E. coli (STEC)
2 types of Shiga toxin produced by EHEC/VTEC/STEC?
Stx1 (Shiga toxin 1)
Stx2 (Shiga toxin 2)
This strain of enteroaggregative strain has caused major outbreaks in Germany.
Produces a “Shiga-like toxin and can cause HUS”
E. coli 0104: H4
Identify the E. coli pathotype (ETEC, EPEC, EHEC, EIEC, EAEC, DAEC)
“The strains are closely related by phenotyping and pathogenic properties to Shigella”
“The bacteria are able to invade and destroy the colonic epithelium, producing a disease characterized initially by watery diarrhea”
“A minority of patients progress to the dysenteric form of disease, consisting of fever, abdominal cramps, and blood and leukocytes in stool specimens”
“Can progress into ulceration”
Enteroinvasive E. coli (EIEC)
What are examples of treatments for Enteric E. coli (Pathotypes) as a substitute for prophylaxis?
Ciprofloxacin
Trimethoprimsulfamethoxazole
It is a disorder characterized by acute renal failure, thrombocytopenia, and microangiopathic hemolytic anemia and is associated with EHEC
Hemolytic Uremic Syndrome (HUS)
Identify the E. coli pathotype (ETEC, EPEC, EHEC, EIEC, EAEC, DAEC)
“All members of this group are defined by the presence of Shiga toxin”
“Some but not all are LEE positive and form A/E cytopathology, resembling EPEC strains”
“Most common in warm months, and highest incidence is in children younger than 5 years old”
Enterohemorrhagic E. coli (EHEC)
Identify the E. coli pathotype (ETEC, EPEC, EHEC, EIEC, EAEC, DAEC)
“Recognized as the 6th class of diarrheagenic E. coli and appear as a heterogenous group”
“Ability to adhere to HEp-2 cells in a diffuse pattern in which the bacteria uniformly cover the entire cell surface”
“Capable of causing diarrheal disease, primarily in children aged 2-6 years”
Diffusely-adherent E. coli (DAEC)
Pathogenic strains of EIEC are primarily associated with a few restricted O serotypes which are?
O124
O143
O164
Who is the bacteriologist that was named after the Klebsiella spp?
Theodor Albrecht Edwin Klebs
Klebsiella pneumoniae was initially known as?
Friedlander’s bacterium
“Brick-red” or “Currant Jelly sputum”, were known to be caused by Friedlander’s bacillus or?
Klebsiella pneumoniae
What strains of K. pneumoniae are considered global priority pathogens?
ESBLs (Extended-spectrum beta-lactamases)
Carbapenemases
True or False
K. pneumoniae are:
Catalase: Positive
Oxidase: Negative
Lactose fermenter
Mucoid colonies
Non-motile
True
It is the most frequently isolated Enterobacter species from man and animals feces
Enterobacter cloacae
Colony characteristic of Klebsiella pneumoniae:
Blood Agar:
MacConkey Agar:
Blood Agar: Mucoid, non-hemolytic
MacConkey: Mucoid, lactose-fermenting (pink colored)
What are notable opportunistic pathogens of Enterobacter? (SAGAC)
E. sakazakii
E. aerogenes
E. gergoviae
E. agglomerans
E. cloacae
IMVC for Klebsiella pneumoniae
IMVC Positive:
IMVC Negative:
IMVC Positive: Indole and Methyl Red
IMVC Negative: Voges-Proskauer and Citrate
A species of Enterobacter that can behave as an opportunistic pathogen in immunologically compromised patients.
E. agglomerans
True or False
The bacteria below are considered to be OPPORTUNISTIC pathogens and NOT ENTERIC
E. cloacae
E. sakazakii
E. aerogenes
E. agglomerans
E. gergoviae
True
A species of Enterobacter that have been implicated in a long term-nosocomial outbreak of urinary tract infections
E. gergoviae
A species of Enterobacter that is often commensal without clinical significance and is occasionally a pathogen causing neonatal meningitis and bacteremia
E. sakazakii
Recommended Media for E. coli: Culture and Maintenance
Blood Agar 5%
TSA Agar
Nutrient Agar
Serratia are positive for these Biochemical Tests (DGLO)
DNAse
Gelatinase
Lipase
ONPG
True or False
For differential of E. aerogenes and E. cloacae, they are BOTH POSITIVE for Ornithine decarboxylase
True
True or False
For differential of E. aerogenes and E. cloacae, they are BOTH NEGATIVE for Alginate Utilization Test
True
Differential Test: E. aerogenes
Lysine decarboxylase:
Arginine dihydrolase:
Urease:
Lysine: Positive (+)
Arginine: Negative (-)
Urease: Negative (-)
Media used for Selective Isolation of Hafnia alvei (5)
EMB (Eosin Methylene Blue)
MacConkey Agar
Hektoen Enteric Agar
SS (Salmonella-Shigella Agar)
XLD Agar (Xylose Lysine Deoxycholate)
Differential Test: E. cloacae
Lysine decarboxylase:
Arginine dihydrolase:
Urease:
Lysine: Negative (-)
Arginine: Positive (+)
Urease: Weakly positive
It is the most common clinical isolate and most important human pathogen in Serratia species
S. marcescens
Colonies of this bacteria and are non-lactose fermenters and may resemble SALMONELLAE
Most strains are translucent or colorless
Media containing sucrose: Red or Pink colonies
Hafnia alvei
Media used for Maintenance of Hafnia alvei (1)
CTA (Cystine Tryptic Agar) at room temperature for up to 1 year
3 species of Serratia best known for clinical infections
S. marcescens
S. liquefaciens
S. odorifera
IMVC reaction of Serratia spp
IMVC: - , - , + , +
Media used for culture of Hafnia alvei (2)
Tryptic Soy Agar
Blood Agar 5%
An opportunistic pathogen which is one of the common cause of UTI and are associated with “Infection-Induced Renal Stones”
Proteus
Certain strains of Proteus vulgaris produce O antigens that are shared by some rickettsiae which are?
OX-19
OX-2
OX-K
Proteus strains are used in this agglutination test for serum antibodies produced against rickettsiae of the typhus and spotted fever groups
Weil-Felix Test
Why is the urease enzyme produced by Proteus species play a major role in the production of infection induced urinary stones?
The ammonia produced after breakdown of urea forms struvite stone formation (magnesium ammonium phosphate)
Recurrent UTI with urease-producing organisms forms “STAGHORN CALCULI” in the kidney
What is the only difference of Proteus mirabilis and Proteus vulgaris in IMVC?
P. mirabilis = Indole negative (-)
P. vulgaris = Indole positive (+)
Between Blood Agar and MacConkey Agar, which does Proteus swarm?
Blood agar = swarms
MacConkey = does not swarm
Several methods to inhibit swarming of proteus
Increased agar concentration from 1-2% to 6%
Choral hydrate (1:500)
Sodium azide (1:500)
Boric acid (1:1000)
Using of Cysteine Lactose Electrolyte Deficient (CLED) as a medium instead of Blood Agar and MacConkey Agar for URINE samples
When two different strains of P. mirabilis swarm on the same agar plate, a visible demarcation line with lower cell density forms at the intersection, and this line is known as? (Hint: named after Louis Dienes)
Dienes Line or Dienes phenomenon
Some Morganella strains appear hemolytic when cultured on BA, while others produce what color pigmentation?
Reddish-brown pigmentation
Culture Media for Morganella spp. (2)
TSA and BA 5%
Maintenance Media for Morganella spp. (2)
Tryptic Soy Agar - short term
Lyophilization - long term
Selective Isolation Media for Morganella spp (4)
MacConkey Agar
EMB Agar
Selenite Broth
Tetrathionate Broth
Providencia IMVC result:
IMVC: + , + , - , +
Identify bacteria based on Macroscopic Appearance:
Large
Dull gray colonies
Non-swarming
Colorless on enteric agar
Providencia spp.
Selective Isolation Media for Citrobacter (9)
MacConkey
EMB
XLD
Selenite Broth
Tetrathionate Broth
SS Agar
Deoxycholate Agar
Brilliant Green Agar (BGA)
Bismuth Sulfite Agar (BSA)
Example of Enteric Agars (3)
EMB Agar
HE Agar
SS Agar
Strains of Providencia _________ and Providencia _________ may produce wound and burn infections
P. stuartii and P. rettgeri
2 species of the genus Salmonella
S. enterica
S. bongori
Common habitat is Extraintestinal tracts (stool samples) of humans and animals (particulary “Poultry”
Providencia spp.
Maintenance agar for Citrobacter
Nutrient Agar
TSA
Brucella with 20% Glycerol
Skim Milk (storage at -70C)
Lyophilization (long term preservation)
Culture Media for Providencia spp. (2)
Tryptic Soy Agar
Blood Agar 5%
Selective Isolation Media for Providencia spp.
Simmons Citrate Agar (SCA)
MacConkey Agar
Tergitol Agar
CHROMtm UTI
Culture Media for Citrobacter (3)
Nutrient Agar
TSA
BA
Recommended pH for Media of Citrobacter
6.8 - 7.2
Maintenance Media for Providencia spp.
TSA or BA5%
Brucella with 20% Glycerol or Skim Milk (Long term storage at -70C)
Lyophilization for preservation
2 Classification of Salmonella based on their serotype
Typhoidal and Non-Typhoidal
Most cases of foodborne disease in humans are caused by bacteria belonging to what Salmonella subspecies?
Salmonella enterica
Only Salmonella that lives in HUMANS: Human acquired
Salmonella typhi
It is acquired by consuming contaminated meat or animal products (EGGS)
Salmonella
True or False
Salmonella typhi or S. typhi have no complex nutritional requirements and readily grow in an ordinary media like Nutrient Agar medium (NA)
True
Examples of Selective Medium for Salmonella and Shigella
DCA medium
SS Agar medium
Wilson & Blair bismuth sulfite medium
XLD medium
Tetrathionate broth
Selenite F broth
Trypticase and Nutrient broth (Liquid Medium)
What type of hemolysis does Salmonella typhi present in Blood Agar?
Gamma hemolysis (no-hemolysis)
Colony color: Grayish-white
These species of Shigella are more resistant because they can tolerate low temperature if adequate moisture is present
Shigella sonnei
For feces specimen, these 2 are the commonly used for the isolation of Salmonella typhi
Selentie F broth
Tetrathionate broth
Causative agent of bacillary dysentery (stool containing blood and pus)
Shigella
In Xylose Lysine Dextrose Agar (XLD) medium, what are the results expected?
Red: due to the fermentation of xylose which lowers the pH of the medium
Pink or Red: presence of Phenol Red
Black center: production of Hydrogen sulfide (H2S)
Deoxycholate Citrate Agar medium result for Salmonella typhi
Colorless because it is NLF
Shigella are differentiated by what antigen?
O antigen
MacConkey Agar for Shigella:
Pale and Yellowish (Non-lactose fermenting)
Exception: S. sonnei being late lactose fermenting (turns pink)
Subgroup of Shigella:
named after “Sonne” in Germany
Ferment lactose and sucrose late
Indole negative
Causes “mildest form” of bacillary dysentery
Subgroup D (Shigella sonnei)
Subgroup of Shigella:
consists of dysentery bacilli
resembles S. flexneri biochemically, but not antigenically
named after “Boyd” who discovered it from India
Isolates “least frequently”
Subgroup C (Shigella boydii)
It is a clinical condition of multiple etiology characterized by frequent passage of blood-stained mucopurulent stool
Dysentery
Subgroup of Shigella:
Named after “Flexner” from Philippines
Mannitol fermenting shigella
Subgroup B (Shigella flexneri)
Subgroup of Shigella:
mannitol non-fermenting
Forms a “toxin”
3 types of toxic activity (Neurotoxicity, enterotoxicity, cytotoxicity)
Subgroup A (Shigella dysenteriae)
Shigellosis has high death rate especially in young children. Most deaths are caused by?
S. dysenteriae type 1
These virulent factors of Y. pestis inhibit phagocytosis and intracellular killing of bacterium inside macrophages
V antigen (protein)
W antigen (acidic lipoprotein)
The “Best” selective media for Shigella and have “RED” colonies
XLD (Xylose Lysine Deoxycholate) Agar
4 structures or subgroup of Shigella
Subgroup A (Dysenteriae)
Subgroup B (Flexneri)
Subgroup C (Boydii)
Subgroup D (Sonnei)
These consists of many proteins which facilitates secretion of virulent factor of Y. pestis in host cells
Resist phagocytic killing and inhibits production of cytokines, which results in reduced inflammatory immune response to infection
Type III secretion system (TTSS)
It is a broth which enrich S. sonnei and S. flexneri but inhibitory to other Shigella
Selenite F-broth
3 pathogenic Yersinia spp.
Y. pestis
Y. pseudotuberculosis
Y. enterocolitica
It is a heat labile protein produced only in the virulent strains when cultures are incubated at 37C in Y. pestis
F1 antigens
This Yersinia spp. is responsible for “RED-MOUTH” , “PINK MOUTH” , or “PINK OR RED THROAT” of salmon and trout
Yersinia ruckeri
These are proteins in nature possessing some properties of BOTH exotoxins and endotoxins
Murine toxins (active in rats and mice)
Yersinia spp. which is the most important cause of food borne illness
Yersinia enterocolitica
What Yersinia species caused the Plague (Black Death)?
Yersinia Pestis
Yersiniosis is caused by what serogroups of Yersinia enterocolitica?
O:3
O:5
O:8
O:9
O:27
True or False
habitat of Y. pestis are found in dogs, squirrels, rabbits, mice, and etc
True
It refers to the endotoxin and murine toxins found in culture filtrates or cell lysates of Yersinia pesits
Plague toxin
These are di-polysaccharide found in the cell wall and is responsible for many of the systemic manifestation of the disease caused by Y. pestis
Endotoxin
Christensen’s Urea Agar for Yersinia
Y. enterocolitica =
E. coli =
Y. enterocolitica = Pink color (urease positive)
E. coli = no color (urease negative)
Bile Esculin Agar (Yersinia spp.)
Y. enterocolitica =
Enterococcus faecalis =
Y. enterocolitica = esculin negative (absence of black color) (except biotype 1A)
Ent. faecalis = esculin positive (black color)
