Microbiology

Question 1

What type of infections can Chlamydia cause?

Answer 1

STI
RTI
Occular infections

Question 2

Describe the life cycle of chlamydia

Answer 2

Consists of 2 forms
1. Elementary body = infectious form that is extracellular and then enters the host cell
Has rigid cell walls cross linked by disulphide bonds

2. Reticulate body = reproductive
   Fragile membrane
   Metabolically active
   Replicates intracellularly

Question 3

Which serotypes of Chlamydia Trachomatis cause Chronic follicular keratoconjunctivitis

Answer 3

Serovars A-C

Question 4

Which serotypes of Chlamydia Trachomatis cause STIs?

Answer 4

Serovars D-K

Question 5

Which serotypes of Chlamydia Trachomatis cause Inclusion conjunctivitis

Answer 5

Serovars D-K

Question 6

Which serotypes of Chlamydia Trachomatis cause LGV?

Answer 6

Serovars L1-L3

Question 7

How is C trachomatis transmitted to cause chronic follicular keratoconjunctivitis?

Answer 7

Transmitted by flies, contact, droplets or contaminated clothes

Question 8

What are the complications of Chronic follicular keratoconjunctivitis?

Answer 8

Multiple re-infaction can cause fibrosis as the follicles in the conjunctival epithelial cells heal by scarring
The eyelashes are pulled in and cause corneal scarring and blindness

Question 9

Red eye, cervicitis with some mucoid discharge - diagnosis?

Complications?

Answer 9

Inclusion body conjunctivitis with concurrent genital tract infection from C. trachomatis serovars D-K
- No corneal scarring or blindness.

Question 10

3 week old baby with red eye and acute watery, mucopurulent discharge.
Diagnosis
complications
treatment

Answer 10

Neonatal inclusion conjunctivitis
Can lead to infant pneumonia syndrome
Treat with oral erythromycin

Question 11

Why is doxycycline contraindicated in pregnant women and infants / children?
What can be used instead?

Answer 11

Causes yellow stained teeth

Instead, use Erythromycin for Chlamydia Trachomatis infection

Question 12

What is the treatment for chlamydia genital infection, inclusion conjunctivitis, LGV

Answer 12

Doxycycline in adults

Erythromycin in children

Question 13

How is Chlamydophila psittaci transmitted?

Answer 13

By inhalation of respiratory secretions or droppings from infected birds

Question 14

What infection is caused by chlamydia psittaci?

Answer 14

Atypical acute pneumonia, often bilateral + severe

Question 15

What is the treatment for Chlamydia psittaci infection?

Answer 15

Doxycycline

Question 16

What types of Chlamydia can cause pneumonia? Do they cause typical or atypical pneumonia?

Answer 16

C. Psittaci
C. Pneumonia
atypical pneumonia

Question 17

What does mycoplasma look like on gram stain?

Answer 17

Doesn’t show up

Question 18

Fried egg colonies

Answer 18

Mycoplasma

Question 19

How is mycoplasma pneumoniae transmitted?

Answer 19

Person to person by respiratory droplets. Prolonged shedding continues after the clinical illness has passed

Question 20

How do patients typically present with a mycoplasma pneumoniae pneumonia?

Answer 20

Atypical
Walking Pneuomia
Self-limiting, mild

Question 21

What extra-pulmonary symptoms can occur with mycoplasma pneumonia infection?

Answer 21

• Haemolytic anaemia with cold agglutinins ( mainly in sickle cell patients)
• Guillan Barre syndrome, encephalitis
• Erythema Multiforme Rash
• Myocarditis, pericarditis
• Raynaud’s phenomenon

Question 22

What is a potential consequence of Q fever in pregnancy?

Answer 22

High conc of coxiella burnetti infection in the placenta can cause abortion / stillbirths

Question 23

How is Coxiella burnetti transmitted?

Answer 23

Via inhalation of aerosols from contaminated soil or animal waste
From unpasteurised milk

Question 24

What is the IP for Coxiella burnetti?

Answer 24

2-5 weeks

Question 25

How does Q fever present if its not asymptomatic?

Answer 25

``` Acute - self-limiting febrile illness - atypical pneumonia - hepatitis - miscarriage or pre-term delivery Chronic - culture negative endocarditis ```

Question 26

Who is at risk of coxiella burnetti infective endocarditis?

Answer 26

Immunocompromised Women infected during pregnancy Prosthetic heart valves

Question 27

What is the treatment of Q fever in pregnancy?

Answer 27

Co-trimoxazole

Question 28

What lab test are done to diagnose Q fever?

Answer 28

NAAT PCR or serology | - will be culture negative

Question 29

What are the antibiotics of choice for infections from Chlamydia, Coxiella burnetti and Mycoplasma? why?

Answer 29

Doxycycline Erythromycin ( Macrolides ) Levofloxacin (Fluroquinolones) They are obligate intracellular pathogens and can't be targeted by their cell wall