BIOL 201 Unit 5-6 Flashcards

Typhoid fever

Caused by Salmonella typhi

Salmonella typhi

Rod-shaped bacterium that grows only in humans (intestines and blood)

Typhoid toxin

Exotoxin produced by S. typhi

AB toxin

Type of toxin that contains two protein subunits: B-subunit and A-subunit

B-subunit

Binds to cell surface receptors, triggering endocytosis

A-subunit

The active toxin that damages the cell

S. typhi modes of transmission

Ingestion of contaminated food, milk, or water; contact with infected individuals; and flies that land on sewage

Typhoid Mary

Cook who infected 51 people, resulting in 3 deaths, isolated in 1907. Died from pneumonia after 26 years in quarantine

Convalescent patient

A carrier for 3 weeks to 3 months after recovery

Typhoid prevention

Good sanitization practices(sewer and water treatment), fly population control, treatment of carriers with antibiotics(Cipro), vaccination

List 3 symptoms of Typhoid fever:

Poor appetite, headaches, mild vomiting, slow heartbeat, fever (103-104 degrees F), lethargy, diarrhea/constipation, dehydration, chest congestion, abdominal pain, generalized aches

Pathogenesis of Salmonella typhi

1. Ingestion of contaminated food or water

2. invasion of small intestine, grows in macrophages and releases typhoid toxin and enters bloodstream

3. Carried by white blood cells to liver, spleen, and bone marrow

4. Multiply and reenters blood stream

5. Bacteria invades gallbladder and lymphatic tissue (multiplies again)

Ty21 (S. typhi vaccine)

vaccine given in oral capsule form (3 dosages), good for 1 year of protection. Available to US Army in 1908 and general public in 1914

Vi capsular polysaccharide (ViCPS)

Injected subunit vaccine with 72% efficacy for about 1.5 years

Vibrio cholerae

Comma shaped bacterium that causes cholera. Growth stimulated by NaCl

Primary habitat of V. cholerae

Marine ecosystems between 18-37°C

Cholera Exotoxin

A toxin secreted by V. cholerae that causes intestinal cells to secrete sodium, leading to diarrhea

Rice Water Diarrhea

Profuse, painless diarrhea and vomiting of clear fluid associated with cholera

Host Risk Factors for Cholera

Children are 10x more susceptible than adults; equal susceptibility in both sexes; low gastric acid levels increase risk

Which blood type is the most susceptible to cholera? The least susceptible?

People with O-type blood are the most susceptible, while AB-types are the least susceptible

Cholera Symptoms

1-3 day incubation period followed by mild to severe diarrhea, muscle cramps, vomiting, and weak pulse

Transmission of Cholera

Primarily fecal-oral route via contaminated water and food; rare person-to-person transmission

Treatment for Cholera

Rehydration and antibiotics(Cipro, Doxycycline, Azithromycin)

Prevention of Cholera

Includes treatment of diseased individuals, vaccines, sewage treatment, and provision of safe water

Vibrio parahaemolyticus, Vibrio vulnificus

Comma shaped marine organism that can infect through wounds and requires salt for growth

V. parahaemolyticus symptoms

watery diarrhea, abdominal cramping, nausea, vomiting, and fever

V. parahaemolyticus infection

occurs through ingestion of undercooked shellfish or exposure of open wounds

V. vulnificus symptoms

wound infections, soft tissue infections, bloodstream infections, fever, chills, skin lesions

V. vulnificus infection

occurs through ingestion of undercooked shellfish or exposure of open wounds

Incubation Period for Cholera

Symptoms appear 1-3 days after ingestion of V. cholerae

Cholera Toxin Encoding

Cholera toxin is encoded by a phage that infects V. cholerae

Sodium Requirement

Sodium is necessary for the growth of V. cholerae

Carriers of cholera

Houseflies and other insects

Reservoirs for cholera

Humans and contaminated water are the main reservoirs

Septic Shock

serious condition that involves V. vulnificus entering the blood stream, which can lead to organ failure