Vibrio and other Gram-negative bacilli

Vibrio

still infects gastrointestinal tract but is not considered as a gram-negative enteric bacilli

O1 & O139

Vibrio cholorae 2 epidemic serotypes

• Classical Vibrio cholorae

• El tor

O1 is Divided into 2 biotypes based on biochemical reactions

• Ogawa

• Inaba

• Hikojima

O1 biotype divided into 3 serotypes based on antigenic difference

Ogawa

containing A & B antigens

Inaba

containing A & C antigens

Hikojima

containing A,B, & C antigens

Clasical Vibrio cholerae

negative in Voges Proskauer at 22 °C,

negative in Chicken erythrocyte agglutination,

Polymyxin B sensitive, Group IV Cholera phage sensitive

El tor

positive in Voges Proskauer at 22 °C,

positive in Chicken erythrocyte agglutination,

Polymyxin B resistant, Group IV Cholera phage resistant

Vibrio

Gram-negative, oxidase positive, Comma-shaped, motile (monotrichous) , acid slant/acid butt, no gas, no H2S in TSI, Ferments Lactose slowly and is String test positive

• Endotoxin

• Enterotoxin

• Flagella

• Mucinase

Determinants of Pathogenicity for Vibrio

Endotoxin

Caused by baby gram-negative bacteria

Enterotoxin

Responsible for diarrhea in vibrio;

has subunits A (A1 &A2) & B

A1

Increase the cAMP —> loss of cell nutrients (Na, H2O,Cl, K, HCO3) / excretion of H2O and electrolytes

—> causing diarrhea

Subunit B

Attaches to the mucosal surface ; allows entry of subunit A into plasma membrane —> increased adenylate cyclase activity

Flagella

Acts as an adhesive & binds the bacteria to cellular surfaces

Mucinase

Enzyme that destroys mucin in intestinal tract; Enables organism to adhere to the cells pf the brush border of the gut or intestinal tract by dissolving the protective glycoprotein coating the intestinal cells.

10⁶ - 10¹¹ CFU

Infecting dose of Vibrio cholorae

Bile salts and organic acids

What environmental factors inhibit Vibrio cholerae growth in the intestine?

Humans

What are the primary reservoirs of Vibrio cholorae?

Houseflies and other insects

What are the carriers of Vibrio cholorae

Bacterium transmitted through contaminated 4Fs (humans to humans) and via contaminated water and food

Mode of Transmission of Vibrio cholerae

2-3 days; may be hours or a few days with a mean of 2-3 days

Incubation period of cholera

Symptoms of cholera

Mild diarrhea, Mucus and intestinal tissue visible in feces, Muscle cramps, Scaphoid abdomen, Vomiting, Loss of skin turgor, Weak pulse, Choleraic facies, Cholera cot

Choleraic Facies

Washerwoman's hand appearance, sunken eyeballs, Due to severe dehydration

Cholera Cot

Used by patients with cholera, hole in the bed with pail under it

Tellurite Taurocholate Gelatin Agar (TTGA) &

Thiosulfate Citrate Bile Salt Sucrose Agar (TCBS)

Culture media for Cholera

Tellurite Taurocholate Gelatin Agar

Flattened, transparent colonies surrounded by a cloudy halo

Thiosulfate Citrate Bile Salt Sucrose Agar

Culture medium of choice

Flat yellow colonies with opaque center and transparent periphery

• Darkfield microscopy

• Stool culture

• ELISA

• Latex agglutination test

Diagnosis of Cholera

Acid slant / acid butt , no gas

LACTOSE FERMENTER

Cholera in Triple sugar Iron

positive

Cholera in Oxidase Test

positive

Cholera in String test

Vibrio parahaemolyticus,

Vibrio vulnificus

Other vibrios

Vibrio parahaemolyticus

Gram-negative, motile, monotrichous, has halophilic vibrio naturally found in marine environment, commonly associated with seafood

Halophilic

Needs 2 % NaCl for optimum growth

4-30 hours, usually 12-24 hours

Incubation period for Vibrio parahaemolyticus

Abdominal pain, diarrhea, vomiting, mild fever

Symptoms of Vibrio parahaemolyticus

Acute gastroenteritis

Vibrio parahaemolyticus common cause is

Gastroenteritis

Self-limiting lasting about 3 days

Vibrio parahaemolyticus

Diarrhea is explosive & watery with no blood & mucus, accompanied by nausea & vomiting, abdominal cramps & sometimes mild (low) fever

Consumption of raw/undercooked seafood or cooked food that has been cross contaminated with bacteria without further cooking

Mode of Transmission for Vibrio parahaemolyticus

Isolation media containing 2% - 4% NaCl

Diagnosis of Vibrio parahaemolyticus

giving of fluids and electrolytes

Treatment for Vibrio parahaemolyticus

Thiosulfate Citrate Bile Salt Sucrose Agar

Culture media used for Vibrio parahaemolyticus

Vibrio parahaemolyticus

In Thiosulfate Citrate Bile Salt Sucrose Agar, it produces green smooth colonies

Vibrio vulnificus

Mostly causes outer ear infection (swimming) & wound infection,

Associated with raw oysters,

Common in warm brackish water, low salt

Bacteremia & Septicemia

what can Vibrio vunificus cause?

Campylobacter

Curved gram-negative rods that appear as comma or S-shaped, or “gull-wing shapes”, Motile and monotrichous, Oxidase positive, failure to grow at 25°C, Sensitive to nalidixic acid, Macroaorophilic, no spore and no capsule

Macroaerophilic

growing best in 5% oxygen rather than 20% present in the atmosphere

Campylobacter Jejuni

diarrhea, grows well at 42°C, major cause of diarrhea in the U.S.A

Campylobacter Intestinalis

Bacteremia,

Does not grow well at 42 °C

• Lipopolysaccharides with endotoxic activity

• Cytopathic extracellular toxins and enterotoxins

Virulence Factors of Campylobacter

(Fecal oral route)

Infection is by Oral route from food, drink, or contact with infected animals or animal products (milk, meat products)

Campylobacter Transmission

Campylobacter

Susceptible to Gastric acid

4-8 days

Incubation period for Campylobacter

Acute enteritis

1 week, stools remain positive for 3 weeks

Acute colitis

Inflammation of colon

Diarrhea, malaise, fever, acute abdominal pain, usually self-limiting

Symptoms of Campylobacter

Enterocolitis

Commonly due to Campylobacter jejuni

1-7 days incubation period,

Begins as watery, foul-smelling diarrhea followed by bloody stools accompanied by fever abdominal pain after an incubation period.

Production of diarrhea is similar to cholera

Systemic Infections

Due to Campylobacter intestinalis,

bacteremia

Skirrow’s medium

CAMPY-BAP

CAMPY-CVA

Medium for stool culture on blood agar

Flat, droplet-like, glistening and tend to spread along the direction of the streak on moist agar

Colonies of Campylobacter jejuni

Helicobacter pylori

Curved bacilli; lophotrichous flagella, very motile, fastidious, microaerophilic, use amino acids and fatty acids rather than carbohydrates to obtain energy, needs 10 % CO2 and 5% O2, Urease +, Catalase + Oxidase +,

grow at 37°C

• Urease

• Motility

• Mucinase

• Adherance factor

• Flagella

Virulence Factors of Helicobacter pylori

Gastritis & duodenal ulcer

Clinical Manifestation of Helicobacter pylori

• Gram-stain

• H&E; Warthin silver stain; Giemsa stain

• Culture

• Endoscopy and biopsy

• Urea breath test

• Catalase & Oxidase test positive

Laboratory Diagnosis of Helicobacter pylori