Gram Negative Bacilli II

Question 1

Pseudomonas aeruginosa

Answer 1

Opportunistic pathogen
Cause of many HCAI
Very common in the environment
Minimal nutritional requirements
Much resistance to antibiotics
Complicated treatment

Question 2

Pseudomonas aeruginosa skin infections

Answer 2

Burns
Skin loss infections
Hot tub folliculitis
Ecthyma gangrenosum (necrotic skin lesions with bacteraemia)
Penetrating foot injuries

Question 3

Pseudomonas aeruginosa other infections

Answer 3

UTIs: from long-term urinary catheters
Otitis externa: swimmer’s ears
Eye infections: cornea trauma then exposure
Bacteraemia: similar to other GN, but higher mortality
Pulmonary infections: particularly cystic fibrosis

Question 4

Burkholderia

Answer 4

Much similarity to Pseudomonas (not normally as bad as Pseudomonas because not as many virulence factors)
In the Pseudomonadaceae.
Common environment isolate.
Opportunistic pathogen.
Minimal growth requirements
Highly adaptable - can grow in disinfectants
Antibiotic resistant.

Question 5

Burkholderia cepacia complex

Answer 5

‘Complex’ because many species but seem identical.
Environmental isolate - cause soft rot in alliums.
Low severity except for pulmonary infections: UTIs, bacteraemia, cystic fibrosis lung infections (poor prognosis).

Question 6

Burkholderia pseudomallei

Answer 6

Bad lung infections.
Causes ‘melioidosis’
Environmental isolate (soil, water, vegetation)
NT, SE Asia, India, Africa endemic infections
Opportunistic infections
At risk groups: alcoholics, diabetes, chronic renal disease, chronic lung disease.

Question 7

Melioidosis

Answer 7

B. pseudomallei usually inhaled.
Leading to pulmonary infection
Mild bronchitis to necrotising pneumonia
Progressing to septicaemia, death
Without treatment septicaemia mortality >80%
A subject of biological weapons research

Question 8

Vibrio

Answer 8

In the Vibrionaceae.
Gram-negative curved rods.
Require salt for growth. 
Prevalent in marine environments.
Important pathogens: C. cholerae, V. parahaemolyticus, V. vulnificus

Question 9

Vibrio cholerae

Answer 9

Cholera - a lethal gastroenteritis
Many epidemics in developing countries
3 to 5 million cases and 100,000 deaths per annum

Question 10

Vibrio cholerae reservoirs and infection.

Answer 10

GIT of humans, marine environments and consumption of contaminated water or food.

Question 11

Vibrio cholerae epidemic strains

Answer 11

01 and 0139 only. All make cholera toxin.

Question 12

Vibrio cholerae symptoms

Answer 12

Profuse watery 'rice water' diarrhoea
Vomiting
Abdominal cramps
Rapid dehydration
Bacteraemia

Mild and self-limiting to severe and fatal.
Morality of up to 60% without effective treatment.
Death from dehydration and electrolyte loss.

Question 13

Vibrio cholerae treatment

Answer 13

Rehydration and electrolyte replacement.

Question 14

Vibrio cholerae prevention

Answer 14

Good sanitation most effective
Prevent faeces mixing with drinking water
Vaccine: available but limited effectiveness.

Question 15

Vibrio parahaemolyticus

Answer 15

Most common bacterial gastroenteritis in Japan and SE Asia

Most common seafood associated gastroenteritis in USA

Question 16

Vibrio parahaemolyticus causes

Answer 16

From consumption of undercooked seafood (particularly oysters)
Also infection of wounds contaminated with dirty saltwater.

Question 17

Vibrio parahaemolyticus symptom

Answer 17

Main symptom is diarrhoea: watery, explosive and self-limiting.
Also nausea, vomiting, abdominal cramps, headache, low grade fever.

Question 18

Vibrio parahaemolyticus treatment and preventions.

Answer 18

Treatment: rehydration and electrolyte replacement.
Prevention: cook shell fish.

Question 19

Vibrio vulnificus

Answer 19

Infrequently isolated
Severe wound infections and gastroenteritis
Capsule allows bacteraemia
Septicaemia in 20-30% of cases
Mortality up to 50% for severe wound infections
Infections from: wounds contaminated with seawater, consumption of raw oysters.

Question 20

Haemophilus influenza

Answer 20

Lung infections