VIRBO

Question 1

Character of vibrio cholerae

Answer 1

1. Gram negative rod
2. Oxidase positive
3. Glucose & sucrose fermenter
4. Motile (flagella)
5. Acid labile
6. NON INVASIVE

Question 2

Hallmark characteristics of vibro species

Answer 2

Biochemical tests: Oxidase positive

Histology: curved (comma) gram negative rods

Question 3

Transmission of vibrio cholerae

Answer 3

faecal oral

Question 4

Treatment of vibrio cholerae

Answer 4

• oral rehydration therapy (replace electrolytes and fluid), severe cases may require IV infusion
• ciprofloxacin/tetracycline (reduces period of pathogen excretion & severity of diarrhoea)

Question 5

Virulence factor of vibrio cholerae

Answer 5

Cholera toxin

1. B subunit (immunogenic): binds to ganglioside receptor on the luminal membrane of enterocytes
2. A subunit: crosses the membrane and activates adenylate cyclase → over-production of cAMP, inhibits active reabsorption of Na+ and HCO3- and water & causes hypersecretion of Cl- and HCO3- with enormous water loss
   - note: strains which lack pili and do not have flagellum are not virulent

Question 6

Transmission of vibrio parahaemolyticus

Answer 6

Contaminated seafood

Question 7

Transmission of vibrio vulnificus

Answer 7

Contaminated seafood, contact between seawater and wounds

Question 8

Clinical presentation of vibrio vulnificus

Answer 8

Food poisoning: self limiting diarrhoea

Acute septicaemia in immunosuppressed individuals (high fever, hypotenion and multiple erythematous skin lesions which become hemorrhagic, necrotic and ulcerating)

Wound infections: cellulitis accompanied by edema, erythema and life-threatening necrosis

Question 9

Treatment of vibro vulnificus

Answer 9

Aggressive surgical wound debridement + combinations of doxycycline, ceftazidime and ciprofloxacin

Question 10

Characteristics of acinetobacter baumannii

Answer 10

NOT fastidious, gram negative rod

Found in the environment and is also normal skin flora

Question 11

Clincial presentation of acinetobacter baumannii

Answer 11

Nosocomial pneumonia due to immunocompromisation

ICU pneumonia, burn patients

Often resistant to multiple antibiotics

Question 12

Clinical presentation of bordetella species

Answer 12

Whooping cough

• catarrhal stage: resemble other respiratory infections
• paroxysmal stage: paroxysmal cough (lungs emptied in a series of cough before dragging in a fresh breath through a narrowed throat which produces the whoop)

Question 13

transmission of bordetella species

Answer 13

respiratory droplets

Question 14

character of legionella pneumophilia

Answer 14

fastidious gram negative bacteria

environmental, grows in water

Question 15

transmission of legionella pnuemophilia

Answer 15

infectious aerosol from colonised water source dispensers (NOT person to person, NOT airborne)

Question 16

clinical presentation of legionella pneumophilia

Answer 16

legionnaires’ disease: severe pneumonia frequently accompanied by confusion/extra-pulmonary manifestations

pontiac fever: brief influenza-like illness, less dangerous

Question 17

diagnosis of legionella pneumophilia

Answer 17

favourite test: antigen detection of urine

immunofluorescent stain on sputum
sample/bronchoalveolar lavage (BAL)

serology

Question 18

treatment of legionella pneumophilia

Answer 18

high dose IV erythromycin/azithromycin (macrolide) or with rifampicin

Question 19

treatment of bordetella species

Answer 19

erythromycin (reduces severity of illness if given before the paroxysmal stage)

Question 20

transmission of yesinia pestis

Answer 20

zoonosis (often through bite of rat flea as it infects rodents), respiratory droplets

Question 21

clincial presentation of yersinia pestis

Answer 21

bubo formation (painful swelling of lymph nodes) with subsequent invasion of bloodstream → pneumonia and septicaemia (plague)

Question 22

Transmission of burkholderia pseudomallei

Answer 22

Direct inhalation of aerosolised bacterium from surface soils and water
Direct inoculation: skin abrasions/contact with superficial wounds