Bacteriology - Campylobacter, Vibrio, Helicobacter Pylori, Haemophilus

Campylobacter?

Gram-negative rod

- Both ends: flagellum "bipolar flagellum" -> enables motility of bacteria

- Thermophilic: thrive in > 42 degrees

- Microaerophilic - they require low conc. of O2, and high conc. of CO2

Reservoir and transmission of campylobacter?

Reservoir: GIT of animals, especially chicken/birds

Transmission: fecal-oral route, a zoonotic infection

Clinical syndromes?

Enteritis:

- Watery diarrhea to gross blood in stool

- C.jejuni is major causative agent

- Culture blood and stool for diagnosis

Bacteremia

- Can make its way to circulation

- C.fetus is responsible

- They are serum resistant

Reactive arthritis/Reiter syndrome:

- As a response to an infection in another part of the body

Possible consequence of C.jejuni?

Guillain-Barré syndrome

- Ascending paralysis

- Demyelination disorder

- Due to molecular mimicry

Treatment of Campylobacter?

Does not require treatment in enteric diseases

- However severe situations: azithromycin

Vibrio?

Gram-negative, comma shaped

- V. cholerae

- V. parahaemolyticus

- V. vulnificus

- Can grow in all temps

- Tolerate alkaline environments

- Oxidase positive

V. cholerae?

Found in water, transmitted by contaminated water

- Also fecal-oral route

V. parahaemolyticus and V. vulnificus - transmission?

Fecal-oral route

- Consumption of raw seafood - oysters

V. cholerae serotypes?

More than 140 O-serotypes

- O1 and O139 are most important

Virulence factor - V.cholerae?

Cholera toxin (endotoxin)

- Causes active secretion of water

- Massive loss of fluid

- Toxin-coregulated pilus

Clinical features - Vibrio?

Perfuse watery diarrhea

- 10-20L lost

V.vulnificus

- Fluminant bacteriaemia and cellulitis

- Have high fatality in alcoholics

Diagnosis - vibrio?

-TCBS agar plate w/ pH 9.0

Prevention - vibrio?

Two vaccines:

- Single dose, live oral

- Killed whole cell w/without toxin B subunit

Treatment - V.cholera?

- Rehydration

- Doxycycline

Helicobacter pylori?

Gram-negative curved rod

- Settles in pylorus of stomach

- Is oxidase positive

- Grows slowly

Virulence factors of H.pylori?

Urease

- Produce ammonia (as it does not tolerate acidity)

- Flagellums

- High motile

- Adhesins

Cytotoxins by H.pylori?

- CagA

- VacA

Transmission H.pylori?

Fecal-oral route

- From human to human

No zoonotic infection, no animals involved

Clinical features - H.pylori?

Gastritis (EMAG)

Ulcers - may develop in stomach or duodenum

Gastric adenocarcinoma - class one carcinogen, 50% of cases

- Cytotoxins

MALToma

Diagnosis - H.pylori?

Urease breath test

- swallow urea, measures CO2 production

Biopsy during endoscopy

CLO test

- 15 min

- test urease activity

Treatment of H.pylori?

Only provided for symptomatic patients

- PPI

- Clarithromycin

- Amoxicillin

Haemophilus?

Gram-negative

- H. influenzae

- H. parainfluenzae

- H. ducrey

- H. aegyptius

Is a coccobacillus

- Is exclusively a human pathogen

- Can be both encapsulated and non-encapsulated

H. influenzae culture?

Chocolate agar

- In addition, needs: NAD+, factor X and hematin

Does not grow on blood agar

Clinical syndromes - heaemophilus?

Pneumonia

Epiglottitis -> almost ALWAYS caused by H.influenzae

- Children

Otitis media

Meningitis

- Only caused by capsulated form bacteria

- Ass w/ type B capsule

Sepsis/septic arthritis:

Only in patients who are splenectomized/sickle cell anemia

What bacterial infections are dangerous for splenectomized patinents?

- H. influenzae

- N. meningitidis

- S. pneumoniae

H. parainfluenzae?

Requires only V factor for growth

- Bronchitis

- Otitis media

- Endocarditis

Ampicillin or amoxicillin

H. durcey?

Sexually transmitted

- Lesions on genitals

H. aegyptius?

Conjunctivitis (pink eye)

- Mostly in children

Prevention - haemophilus?

There is vaccine available

- Only contains a specific type of the capsular antigen; type B capsule

- Conjugated to the diptheria toxoid

Treatment haemophilus?

Beta-lactams for local infections

Ceftriaxone for meningitis

Rifampicin for prophylactic treatment