18. b. Rickettsia, Coxiella and Mycoplasma

Question 1

How are the rickettsiae transmitted?

Answer 1

Via insects

Question 2

What species of rickettsia causes rocky mountain fever?

Answer 2

R. rickettsia

Question 3

What species of rickettsia cause typhus?

Answer 3

R. prowazekii and murine

Question 4

What gram stain are the rickettsia?

Answer 4

negative

Question 5

Where does rickettsia localise?

Answer 5

In endothelial cells of small blood vessels

Is an obligate intracellular pathogen

Question 6

What host factors increase the virulence of rickettsia?

Answer 6

Old age

G6PD deficiency

Question 7

What are the clinical features of a rickettsia infection?

Answer 7

Fever, headache
Intense myalgia
Rash
GI involvement
In typhus: bradycardia despite fever

Question 8

How is rickettsia diagnosed?

Answer 8

Weil-felix test on serology

Question 9

What antibiotic is used to treat rickettsia?

Answer 9

Doxycycline

Question 10

How does coxiella burnetii get into the body?

Answer 10

Inhalation of aerosols of contaminated placenta or ingestion of raw milk

Question 11

What disease is caused by coxiella burnetii?

Answer 11

Q fever

Question 12

What are the symptoms of acute Q fever?

Answer 12

50% asymptomatic
Flu-like
Pneumonia
Hepatitis

Question 13

What are the risks of Q fever in pregnancy?

Answer 13

Increases risk of intrauterine death
Grow retardation
Prem delivery

Question 14

What diseases are caused by chronic Q fever?

Answer 14

Culture negative endocarditis

Osteomyelitis and vascular graft infection

Question 15

What cell does Coxiella reside in?

Answer 15

Macrophages

Question 16

Which bacteria from this lecture produces spores?

Answer 16

Coxiella

Question 17

Which phase antigen of coxiella is highly infectious?

Answer 17

Phase 1

Only need one bacterium to cause infection

Question 18

How is Coxiella diagnosed?

Answer 18

Serology:
increase in phase 2 antibodies in acute infection
increase in phase 1 antibodies in chronic

Question 19

What biosafety level is needed for Coxiella?

Answer 19

3

Question 20

What is the treatment for an acute coxiella infection?

Answer 20

Doxycycline

Question 21

What is the treatment for a chronic coxiella infection?

Answer 21

Doxycycline and rifampicin for a prolonged period

Question 22

What diseases are caused by mycoplasma pneumoniae?

Answer 22

Upper and lower RTIs

Question 23

What precautions are needed for mycoplasma pneumoniae?

Answer 23

Droplet

Question 24

What age group is mycoplasma pneumoniae most common in?

Answer 24

Young children

Question 25

What are the symptoms of an m. pneumoniae upper RTI infection?

Answer 25

Cough
Pharyngitis
Rhinorrhoea
Ear pain

Question 26

What are complications of m. pneumoniae infection?

Answer 26

Haemolysis
Skin rash (Stevens Johnson syndrome)
Carditis
Encephalitis

Question 27

How is M. pneumoniae diagnosed?

Answer 27

PCR of sputum

Question 28

What is the treatment of M. pneumoniae?

Answer 28

Macrolides or doxycycline

Question 29

Where does M. hominis colonise?

Answer 29

Genital tract

Increases with sexual activity

Question 30

What disease is caused by M. hominis?

Answer 30

Chorioamnionitis (pelvic inflammatory disease)

Question 31

What diseases are caused by ureaplasma urealytium?

Answer 31

Postpartum and postabortal fever
Neonatal pneumonia
Bacteraemia
Abscesses

Question 32

How is M. hominis diagnosed?

Answer 32

culture

PCR

Question 33

How is M. Hominis treated?

Answer 33

Doxycycline