Gram Negative Bacteria

Question 1

State 3 virulence factors for Bordetella pertusis

Answer 1

1. Filamentous haemagglutinin
2. Tracheal cytotoxin
3. Pertusis toxin

Question 2

What are the prevention steps that can be taken to prevent neisseria meningitidis?

Answer 2

1. Rifampicin chemoprophylaxis for close contacts of meningitis case
2. Meningococcal vaccine (capsule serotype A, C, Y, W135)

*source of bacteria is in nasopharynx and spread through droplet

Question 3

A 50-yo male diagnosed with gastritis. Urea breath test is positive. What is the organism causing it?

Answer 3

Helicobacter pylori

Disease:
•Gastritis
•Duodenal ulcer
•Gastric carcinoma

*person-to-person transmission via faecal oral route

Virulence factor:
•Protease
•Urease

Treatment:
•Proton-pump inhibitor + metronidazole

Question 4

A Jane Doe who is a sex worker is diagnose to have genital tract infection. Her genital specimen culture on Thayer-Martin agar shows gram -ve diplococci. What is the most likely etiological agent?

Answer 4

Neisseria gonorrheae

Also cause:
•Pelvic inflammatory disease
•Ophthalmia neonatrum

• Clue is growth on Thayer-Martin agar bc neisseria meningitidis only grows on chocolate agar.
• Glucose fermentation only (as opposed to neisseria meningitidis - glucose & maltose fermentation)

Virulence factor:
•Pili
•Lipooligosaccharide
•IgA1

Treatment:
•Ceftriaxone

Question 5

Name three coccobacilli organisms

Answer 5

1. Bordetella pertusis (Whooping cough)
2. Haemophilus influenzae
3. Haemophilus parainfluenzae (Endocarditis)
4. Haemophilus ducreyi (Chancroid)

Question 6

List all gram -ve curve rods

Answer 6

1. Vibrio cholerae
2. Campylobacter jejuni
3. Helicobacter pylori

Question 7

A Jane Doe was diagnosed with epiglottitis. Culture of her throat swab grew pleomorphic gram -ve coccobacili on chocolate agar. The most likely bacteria is

Answer 7

Haemophilus influenzae

Virulence factor:
•Endotoxin
•Polysaccharide capsule
•IgA protease

*Other diseases caused (mostly related to respi system)

1. Meningitis
2. Osteomyelitis
3. Otitis media
4. Pneumonia

Treatment for haemophilus influenzae:
•Amoxillin/ampicilin
•3rd gen cephalosporins (ceftriaxone, cefotaxime)

Prevention:
•Rifampicin chemoprophylaxis
•HiB vaccine

Question 8

Neisseria meningitidis is a cause of meningitis. What would be the virulence factors of the bacteria?

Answer 8

1. Polysaccharide capsule
2. Lipooligosaccharide (LPS)
3. IgA1 protease

• for neisseria gonorrhea - pili, lipo, IgA1
• also cause meningococcaemia

Question 9

Treatment: Erythromycin
Prevention: Erythromycin prophylaxis
Growth on Bordet-Gengou
Slide agglutination test

What is the possible bacteria?

Answer 9

Bordetella pertusis

Question 10

What are the diseases caused by moraxella catarrhalis?

Answer 10

1. Bronchitis
2. Bronchopneumonia
3. Sinusitis
4. Otitis media

Question 11

• Facultative anaerobes
• Grow easily on blood & MacConkey agar
• Oxidase negative
• Some are LF & nLF

The following are the properties for what organism?

Answer 11

Enterobacteriaceae (enteric bacilli)

Question 12

What are the diseases caused & the virulence factors of E. Coli?

Answer 12

1. UTI (pili)
2. Neonatal meningitis (K1 capsule)
3. Diarrhea
4. Cholera-like heat labile toxin

Virulence factors:
•Pili
•K1 capsule
•Enterotoxin

Question 13

These organisms cause:
•opportunistic infection in compromised host
•UTI
•RTI
•Pneumonia

Answer 13

• Klebsiella pneumoniae
• Enterobacter
• Serratia

Question 14

This organism swarms in blood agar.

It causes:
•UTI
•Septicaemia
•Hospital-acquired wound infection

Answer 14

Proteus

Virulence factor:
•Urease
•Endotoxin

Question 15

What is melioidosis and its etiological agent?

Answer 15

When it presents as lung infection & multiple abscesses in organs

•Burkholderia pseudomallei

Question 15

Disease:
•Intra abdominal sepsis
•Liver abscess
•Wound infection

Treatment:
•Metronidazole

What is the organism and its lab diagnosis?

Answer 15

Bacteroides fragilis

• Small, pleomorphic rods
• Foul odour
• Non-spore forming
• Anaerobic

Question 17

What does Shigella cause?

Answer 17

Dysentery

Question 18

Name two nonmotile enterobacteriaceae organisms.

Answer 18

• Shigella

* Klebsiella

Question 18

Virulence factors:
•Enterotoxin
•Mucinase
•Adhesins

Disease: Profuse water diarrhea

Treatment: Tetracycline & doxycycline

Lab test: Thiosulphate Citrate Bile Salts = Yellow colony & grow in alkaline condition

What is the organism?

Answer 18

Vibrio cholerae

Only in human reservoir

Question 20

What diseases do acinetobacter baumanni cause)

Answer 20

• Bacteraemia

* Ventilator-ass pneumonia

Question 21

• Infections of skin & burns
• RTI in cystic fibrosis
• Ventilator-ass pneumonia
• septicemia, UTI, Osteomyelitis, endocarditis (basically infections everywhere)
• Oxidase positive
• Produce green pigment
• Strict aerobes

What is the organism and its virulence factors)

Answer 21

Pseudomonas aeruginosa

Virulence factors:
•Endotoxin
•Exotoxin A
•Polysaccharide capsule

Question 22

S. Typhi - Thyphoid (antibiotic)
S. Parathyphi - Enteric fever (antibiotic)
S. Enteritisis - Diarrhea (symptomatic treatment)

What are the virulence factors for Salmonella sp?

Answer 22

• Vi capsular antigen -prevent complement binding
• Ability to invade gut mucosa

Prevention steps:
•Identify & treat carriers
•Vaccine for S. Typhi
•Hand hygiene
•Proper preparation of poultry n food