Gram-negative bacilli Flashcards

1
Q

What are the identifiable features of P. aeruginosa?

A

Oxidase positive, gram negative rod/bacilli

Produces green pigment

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1
Q

What is P. aeruginosa commonly associated with?

A
  1. Opportunistic infections - major cause of nosocomial infections
  2. Contact lens keratitis
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2
Q

What are some of the common nosocomial infections caused by P. aeruginosa?

A
  1. Pneumonia
  2. UTI
  3. SSTIs

All may progress to bacteraemia/septicaemia

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3
Q

What are some common community-acquired infections caused by P. aeruginosa?

A
  1. Malignant otitis externa - especially in elderly diabetic patients
  2. Contact lens keratits
  3. Nail infection
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4
Q

How is B. pseudomallei identifiable?

A

Gram-negative bacilli, grows as wrinkled colonies

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5
Q

What gram-negative bacilli infection is notifiable to MOH?

A

Burkholderia pseudomallei & V. cholerae infection

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6
Q

What does B. pseudomallei infection cause?

A

Melioidosis

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7
Q

What is the most common environmental source of B. pseudomallei infections?

A

Surface soil or water

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8
Q

What are the common clinical presentations of melioidosis?

A
  1. Septicaemia
  2. Pneumonia
  3. Chronic infection
  4. Abscesses
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9
Q

What are the groups at risk for melioidosis?

A
  1. Immuno-compromised - e.g. diabetics, 40-70% of patients have DM
  2. Occupations with exposure to soil and water
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9
Q

Is B. pseudomallei intracellular or extracellular?

A

Intracellular

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10
Q

How is melioidosis diagnosed?

A

Blood culture or serology

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11
Q

What are the 2 countries associated with B. pseudomallei infections?

A

North Australia and North-Eastern Thailand

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12
Q

What group of people is B. cepacia infamous for infecting?

A

Patients with cystic fibrosis

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13
Q

What is the main virulence factor of V. cholerae?

A

Cholera toxin

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14
Q

How are the Vibrio spp. transmitted?

A

Water & raw seafood

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15
Q

Which Vibrio spp. is associated with SSTIs, fascitis & septicaemia?

A

V. vulnificus

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16
Q

Which V. cholerae strain carries the cholera toxin?

A

Type O1 & Type O139

17
Q

What is the hallmark of cholera?

A

Ricewater stool; copious watery painless diarrhoea

18
Q

What is the main virulence factor of H. influenzae?

A

Antigenically distinct polysaccharide capsule

19
Q

Why is H. influenzae ‘fussy’?

A

Dependent on both X and V

20
Q

What are the invasive infections caused by H. influenzae type b?

A
  1. Meningitis
  2. Acute epiglottitis
  3. Septicaemia
  4. Pneumonia
  5. Osteomyelitis, septic arthritis
  6. Cellulitis
21
Q

How is H. influenzae prevented around the world?

A

Hib conjugated vaccine

22
Q

What agar is used to grow H. influenzae?

A

Chocolate agar

23
Q

What antibiotic should be given for severe H. influenzae infections?

A

Ceftriaxone (preferred) / Co-amoxiclav

Some H. influenzae strains produce beta lactamases and hence it is safer to give ceftriaxone from the beginning to minimise unresponsiveness to treatment due to AMR

24
Q

What antibiotic should be given for mild URTI infections caused by H. influenzae in the community?

A

Amoxicillin

25
Q

What disease is the HACEK group comonly associated with?

A

Endocarditis

26
Q

What disease does B. pertussis cause?

A

Pertussis or whooping cough

27
Q

How is pertussis diagnosed?

A

PCR

28
Q

How is pertussis prevented?

A

DTaP vaccine for children and pregnant women

29
Q

What is the history to take note of from a patient with Brucellosis?

A
  1. PUO
  2. Travel history to Middle East
  3. Drinking unpasteurized milk
30
Q

Which microbial infection is caused by cat scratches and lice?

A

Bartonella spp.

31
Q

What microbe is associated with animal bites (including cats & dogs)?

A

Pasteurella multocida

32
Q

Which microbial spp. causes the plague?

A

Yersinia spp.

33
Q

What is Legionella commonly associated with?

A

Water & aircon units

34
Q

What are the clinical presentations of a Legionella infection?

A
  1. Pneumonia
  2. Pontiac fever
35
Q

How is Legionella infection diagnosed?

A
  1. Urine antigen test
  2. Broncho-Alveolar Lavage culture -> immunofluorescent stain -> NAT
36
Q

What microscopic finding supports the diagnosis of Bacillary vaginosis?

A

Clue cells

37
Q

What infection is typically caused by Acinetobacter spp. and who are the at-risk groups?

A

Causes nosocomial pneumonia

Typically affects the immuno-compromised (ICU, burn patients)

38
Q

Treatment for melioidosis?

A

Ceftazidime or imipenem; 2 week IV

6 months oral maintenance

39
Q

Identifiable features of V. cholerae?

A

Curved GNR, yellow on TCBS

Thiosulphate Citrate Bile Salts & Sucrose

40
Q

Which bacteria grows ‘wrinkled’ colonies?

A

Burkholderia pseudomallei

41
Q

Which bacteria grows ‘mercury droplet’ colonies?

A

Bordetella pertussis

42
Q

What are the 2 criteria used to diagnose bacillary vaginosis?

A
  1. Amsel criteria
  2. Nugent criteria