NON ENTERIC GASTROINTESTINAL PATHOGEN Flashcards by Antea Eper

Comma/curved bacillus

Vibrio

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It is found in brackish or estuarine water, and marine water or salt water. It is temperature sensitive (> 20°C) and it can be isolated from algae, plankton, fish and shellfish.

Vibrio

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Facultative anaerobe, monotrichous, halophillic organism (halophilic except V. cholerae and R. mimicus)

Vibrio

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Vibrio spp. are halophilic except…

V. cholerae and R. mimicus

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Microscopic appearance of Vibrio

Gram negative short, curved rod
Asporogenous

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Susceptibility test for Vibrio spp.

150ug VIbriostatic disk on MHA or TSA (01/29)

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Virbio mode of acquisition

Consumption of raw or undercooked seafoods

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Diseases /Infection associated with Vibrio

Cholera, wound infection, septicemia and necrotizing fasciitis

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Smooth, opaque, Iridescent with a greenish hue (CAP)
a or ß hemolysis (BAP)

Oxidase (+)
Reduce nitrates to nitrite
Glucose fermenter, NLF
Motility test: polar sheated flagella (broth)
Peritrichous, unsheated flagella (solid media)

Vibrio

Reduce nitrates to nitrite except V. metschnikovii
Glucose fermenter, NLF except V. vulnificus

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Vibrio spp. that causes the most severe disease

V. vulnificus

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The causative agent of cholera/asiatic cholera/epidemic cholera

V. cholerae 01

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The single flagellum Is covered with lipopolysaccharide sheath. It has rapid darting or shooting-star motility.

Vibrio cholerae

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Vibrio cholerae has caused Cholera epidemic (_____strains) and seven pandemics (______ strains)

01 and 0139 strains
01 strains

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Epidemic V. cholerae 01 biogroups

Classical
El tor

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VP (-); do not agglutinate chicken RBC, susceptible to polymixin B (50kg)

Classical V. cholerae 01

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VP (+); agglutinate chicken RBC; resistant to polymixin B (50/g).

El tor V. cholerae 01

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Vibrio cholerae potent enterotoxins

Cholera toxin (CT)
Zot toxin
Ace toxin

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Vibrio cholerae virulence factor

Choleragen

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String test reaction of Vibrio cholerae

Mucoid “stringing” reaction

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Vibrio cholerae antigenic structures

Somatic O and Flagellar H (V. cholerae subgroups)

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Virbio cholerae TSI reaction

A/A, (-) gas, (-) H2S

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Mode of acquisition of Cholera

Mainly through contaminated water
Ingestion of improperly preserved food like seafoods (shellfish), milk and ice cream

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It is an acute diarrheal disease with rice-watery stool (10-30x of defecation/day)

Cholera

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2 functional units of choleragen

Enzymatic A subunit Intestinal receptor-binding B subunit

How does choleragen stimulate diarrhea?

A subunit choleragen enters the intestinal epithelial cells and activates the enzyme adenylate cyclase by the addition of an ADP-ribosyl group in a way similar to that employed by diptheria toxin

Responsible for the stimulation of hypersecretion of water and chloride ions while Inhibiting absorption of sodium ions, leading to massive fluld loss (10-15 liters) and electrolytes

Choleragen

____ provides the attachment to mucosal cells for cholera toxin release

Toxin-coregulated pili (TCP)

Allows for the penetration of the mucosal layers

Mucinase

The second most common Vibrio species Implicated in gastroenteritis

Vibrio parahaemolyticus

 It is the etlologic agent of "summer diarrhea" in Japan

Vibrio parahaemolyticus

Vibrio parahaemolyticus pandemic strain

V. parahaemolyticus serotype Us:K6

Vibrio parahaemolyticus mode of acquisition

Eating contaminated seafoods like oyster, scallops, crabs, lobsters and shrimps, and even sardines

Vibrio parahaemolyticus virulence factor

Heat-stable hemolysin

The phenomenon wherein hemolysis is induced by hemolysins

Kanagawa phenomenon

Bacteria associated with kanagawa phenomenon

Vibrio parahaemolyticus

Selective medium for Vibrio parahaemolyticus

Wagatsuma agar (high-salt mannitol medium)

Strains of Virbio parahaemolyticus that can lyse human RBCs is known as…

Konagawa toxin positive.

It was commonly referred to as the "lactose-positive" Vibrio

Vibrio vulnificus

Second to V. cholerae in terms in producing serious type of Vibrio-associated infection

Vibrio vulnificus

Infections caused by Vibrio vulnificus

Primary septicemla and wound Infections

Mode of acquisition of Vibrio vulnificus

Eating raw oysters and fish (Tilapla)

The least pathogenic Vibrio for humans and is not commonly Isolated.

Vibrio alginolyticus

Vibrio spp. that is a strict halophile (I% to 10% NaCl). It can be an occupational hazard to fishermen and sailors. 

Vibrio alginolyticus

Specimen for Vibrio

Stool Rectal swab Pus Tissue

Transport medium for Vibrio species

Only Cary-Blair medium

Vibrio spp. require media containing O5% NaCl except…

V. cholerae and V. mimicus

Vibrio that tolerates up to 10% NaCl

Virbrio alginolyticus

Pathogenic vibrio grows as ___ on Mac Conkey agar

NLF

Alkaline peptone water with 1% NaCl (pH 8.5) can be inoculated (at least 20 mL) and incubated for ______________ before subculturing to TCBS

5-8 hours at 35ºC

Which Vibrio spp. are sucrose fermenters (yellow colonles on TCBS):

V. cholerae V. alginolyticus V. metschnikovii

Which Vibrio spp. are nonsucrose fermenters (green colonies on TCBS):

V. mimicus V. vulnificus V.parahemolyticus V. damsela

Reagent used for string test

0.5% Sodium desoxycholate

It differentiates Vibrio spp from Aeromonas spp

String test

Positive reaction of string test

Lysis of cells (Vibrio) - releases DNA, which can then be pulled up into a string (viscous string) using an Inoculating loop

Susceptibility test for Vibrio

Vibriostatic test - 0/129 (2,4-dlamino-6,7-dilsopropylpteridine)

It is used to separate vibrios (susceptible) from other oxidase-positive, glucose fermenters like aeromonads (resistant). It will also differentiate V. cholerae 01 an non-01 (suscenptible) form other Vibrio spp. (resistant)

Vibriostatic test

LIA: K/K (+) Citrate; yellow colonies on TCBS = V. cholerae (+) Indole: V. cholerae, V. mimicus and V. vulnificus nev (+) cellobiose: V. vulnificus API 20E

Vibrio

Best test method for Vibrio spp.

API 20E

Found in fresh water, estuarine, chlorinated water, and can be isolated from meat products

Aeromonas

Causative agent of “red leg” disease in frogs

Aeromonas

Culture of Aeromonas

“Bulls eye colonies” apron-like pattern (CIN with 4 ug cefsulodin) LF (MAC — A. caviae)

Temperature in which Aeromonas can grow

4º-42º C

Extraintestinal infections caused by Aeromonas

Septicemia Meningitis Keratitis Wound infections

Most common Aeromonas isolate

Aeromonas caviae

Common Aeromonas isolates in GI infections

Aeromonas caviae

Common Aeromonas isolates is HUS

Aeromonas hydrophila Aeromonas veronii

It is the most recognized antecedent cause of Guillain-Barre syndrome

Campylobacter

 It is also an animal pathogen (cattle and swine) causing sterility and abortion

Campylobacter

Microscopic appearance of old cultures of Campylobacter

Faintly staining Gram-negative, small, curved or S-shaped rod may appear as coccobacilli

Microscopic appearance of enteric Campylobacter

Long spirals or seagull-wing shaped

Culture morphology of Campylobacter

Gray, flat, glistening, irregular, with a "tailing effect along the streak line" or "runny spreading" colonial growth

Mode of acquisition of Campylobacter

Ingestion of contaminated water, poultry and dairy products Handling pets Sexually transmitted

Enteric campylobacters

C. Jejuni C. coli C. lari

it is the most common cause of bacterial gastroenteritis worldwide acquired through eating contaminated chicken and turkey (does not multiply in food)

Campylobacter jejuni

It invades the epithellum of the small intestine, causing inflammation and secretes a toxin that is antigenically similar to the cholera toxin. It also causes septic arthritis (AIDS)

Campylobacter jejuni

It is slow growing, fastidlous and asaccharolytic; darting motility; unable to grow in 3.5% NaCl

Campylobacter jejuni

 Optimum temperature for Campylobacter jejuni growth

42°C

 Microscopic appearance of Campylobacter jejuni

Curved or seagull-winged shaped

 Infective dose Campylobacter jejuni

≥10,000 organisms

Campylobacter isolated most frequently from blood cultures (37°C incubation) and is rarely associated with gastrointestinal illness.

Campylobacter fetus

Specimens for the diagnosis of Campylobacter include feces, rectal swab, blood. What is the preferred specimen for Campylobacter spp. that cause enteric illness?

Stool samples Rectal swab Is a less-preferred specimen

Recommended counterstain for Campylobacter

Carbolfuchsin

If safranin is the secondary stain for Campylobacters, it should be applied for _________

2-3 minutes

Motility test for Campylobacter

Hanging Drop preparation: (+) darting motility

To observe the typical motility, organisms should be suspended in _______

Brucella or TSB

In blood culture, __ weeks incubatlon may be needed for detection of Campylobacter

2 weeks

Campylobacter Is detected effectively by

CO2 monitoring

___ is used for direct detection of C. jejuni and C. coli in fecal specimens

EIA

Are susceptible to the nonspecific bactericidal activity of normal human serum

C. jejuni

It is found in the GIT of mammals and birds

Helicobacter

Gram-negative spiral-shaped organisms (S-shaped) rods resembling campylobacter Motile (monopolar or multi-bipolar flagella) Microaerophillc Most specles have strong urease activity Oxidase and catalase (+) Strong urease activity

Helicobacter

It is the major cause of type B gastritis, peptic ulcer and gastric carcinoma

Helicobacter pylori

 Its motility allows this organism to escape acidity of the stomach

Helicobacter pylori

Plays a significant role in the survival of Helicopbacter pylori and growth by creating an alkaline microenvironment - generates ammonium from urea, thus neutralizing gastric acid

Urease enzyme

Bacteria that binds to Lewis antigen and to the monosaccharide sialic acid

Helicobacter pylori

Specimens for Helicobacter

Tissue biopsy material (Stuart's medium) Urine (ammonia testing) Feces Dental plaque

Tissue specimens should be maintained at ___ and processed within ___ of collection

4ºC, 2 hours

Transport medla for Helicobacter

Stuart's media, cystelne-brucella broth w/ 20% glycerol (tissue samples) and Isotonic saline with 4% glucose

What organism has excellent sensitivity and specificity with Urea breath test

Helicobacter

Metronidazole susceptibility test of Helicobacter pylori

Susceptible

NON ENTERIC GASTROINTESTINAL PATHOGEN Flashcards

(101 cards)