Lesson 10: The Enterobacteriaceae Flashcards by Merch Paul Eli Silvederio

Bacteria found in the Family Enterobacteriaceae (ESSEPY)

Escherichia
Shigella
Salmonella
Enterobacter
Proteus
Yersinia

How well did you know this?

Not at all

Perfectly

Enterobacteriaceae are:

Gram-negative
Short rods
Non-sporulating
Facultative anaerobes

True

How well did you know this?

Not at all

Perfectly

It is an agar used to isolate and differentiate organisms of Enterobacteriaceae family

MacConkey agar

How well did you know this?

Not at all

Perfectly

MacConkey agar differentiates lactose fermenter coliforms from Non-lactose fermenters by what colors?

Lactose fermenter: Pink colored
Non-Lactose fermenter: Pale colored

How well did you know this?

Not at all

Perfectly

Lactose Fermenters (CEEK)

Citrobacter
Escherichia
Enterobacter
Klebsiella

How well did you know this?

Not at all

Perfectly

Are enterobacteriaceae Cytochrome C oxidase negative or positive?

Cytochrome C oxidase negative (-)

How well did you know this?

Not at all

Perfectly

Non-Lactose Fermenters (ShYPS)

Shigella
Yersinia
Proteus
Salmonella

How well did you know this?

Not at all

Perfectly

Are enterobacteriaceae catalase positive or negative?

Catalase positive (+)

How well did you know this?

Not at all

Perfectly

Non-Lactose Fermenters
Nonmotile and Non-H2S producing

Shigella
Yersinia

How well did you know this?

Not at all

Perfectly

Non-Lactose Fermenters
Motile and H2S producing

Proteus
Salmonella

How well did you know this?

Not at all

Perfectly

True or False

Pseudomonas and other oxidase positive bacteria reduce NITRATE to NITROGEN GAS

True

How well did you know this?

Not at all

Perfectly

True or False

Enteric bacteria usually reduces NITRATE to NITRITE

True

How well did you know this?

Not at all

Perfectly

Oxidase positive bacteria (PAVAAFC)

Pseudomonas
Aeromonas
Vibrio
Alcaligenes
Achromobacter
Flavibacterium
Cardiobacterium

How well did you know this?

Not at all

Perfectly

Characteristic antigen of Enterobacteriaceae

Enterobacterial Common Antigen

How well did you know this?

Not at all

Perfectly

4 Enterobacterial Common Antigens

O: Outer membrane
H: Flagella
K: Capsule
Vi: Capsule of Salmonella

How well did you know this?

Not at all

Perfectly

Does enterobacteriaceae produce acid from glucose and have the ability to ferment lactose?

Yes

How well did you know this?

Not at all

Perfectly

Biochemical Tests to Identify Enterobacteriaceae family

IMVC Test
Motility Test
Triple Sugar Iron (TSI) Agar Test
Urease Test

How well did you know this?

Not at all

Perfectly

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

How well did you know this?

Not at all

Perfectly

Citrate medium most commonly used in the citrate utilization test is?

Formula of Simmons

How well did you know this?

Not at all

Perfectly

Utilization of exogenous citrate requires the presence of citrate transport proteins known as?

Permeases

How well did you know this?

Not at all

Perfectly

Upon uptake by the cell, citrate is cleaved by citrate lyase into?

Oxaloacetate and acetate

How well did you know this?

Not at all

Perfectly

Oxaloacetate is metabolized into?

Pyruvate and CO2

How well did you know this?

Not at all

Perfectly

Citrate Test: POSITIVE (SPPECKS)

Serratia marcescens
Providencia
Proteus mirabilis
Enterobacter spp.
Citrobacter freundii
Klebsiella pneumoniae
Salmonella (other than Typhi and Parathypi A)

How well did you know this?

Not at all

Perfectly

Under alkaline conditions, pyruvate is metabolized to?

Acetate and formate

How well did you know this?

Not at all

Perfectly

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 1. Proteus spp. and Enterobacteriaceae 2. Helicobacter pylori and tissue biopsy material 3. Cryptococcus neoformans and Candida albicans 4. Urea breath test: Helicobacter pylori

1. Proteus spp. which is urease positive is differentiated from Enterobacteriaceae family which are non-lactose fermenting 2. Crushed tissue biopsy is placed into urease broth and if it is positive, there is the presence of Helicobacter pylori 3. Cryptococcus neoformans is a rapid urease producer while Candida albicans are not 4. 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)