18. b. Rickettsia, Coxiella and Mycoplasma Flashcards
How are the rickettsiae transmitted?
Via insects
What species of rickettsia causes rocky mountain fever?
R. rickettsia
What species of rickettsia cause typhus?
R. prowazekii and murine
What gram stain are the rickettsia?
negative
Where does rickettsia localise?
In endothelial cells of small blood vessels
Is an obligate intracellular pathogen
What host factors increase the virulence of rickettsia?
Old age
G6PD deficiency
What are the clinical features of a rickettsia infection?
Fever, headache Intense myalgia Rash GI involvement In typhus: bradycardia despite fever
How is rickettsia diagnosed?
Weil-felix test on serology
What antibiotic is used to treat rickettsia?
Doxycycline
How does coxiella burnetii get into the body?
Inhalation of aerosols of contaminated placenta or ingestion of raw milk
What disease is caused by coxiella burnetii?
Q fever
What are the symptoms of acute Q fever?
50% asymptomatic
Flu-like
Pneumonia
Hepatitis
What are the risks of Q fever in pregnancy?
Increases risk of intrauterine death
Grow retardation
Prem delivery
What diseases are caused by chronic Q fever?
Culture negative endocarditis
Osteomyelitis and vascular graft infection
What cell does Coxiella reside in?
Macrophages
Which bacteria from this lecture produces spores?
Coxiella
Which phase antigen of coxiella is highly infectious?
Phase 1
Only need one bacterium to cause infection
How is Coxiella diagnosed?
Serology:
increase in phase 2 antibodies in acute infection
increase in phase 1 antibodies in chronic
What biosafety level is needed for Coxiella?
3
What is the treatment for an acute coxiella infection?
Doxycycline
What is the treatment for a chronic coxiella infection?
Doxycycline and rifampicin for a prolonged period
What diseases are caused by mycoplasma pneumoniae?
Upper and lower RTIs
What precautions are needed for mycoplasma pneumoniae?
Droplet
What age group is mycoplasma pneumoniae most common in?
Young children
What are the symptoms of an m. pneumoniae upper RTI infection?
Cough
Pharyngitis
Rhinorrhoea
Ear pain
What are complications of m. pneumoniae infection?
Haemolysis
Skin rash (Stevens Johnson syndrome)
Carditis
Encephalitis
How is M. pneumoniae diagnosed?
PCR of sputum
What is the treatment of M. pneumoniae?
Macrolides or doxycycline
Where does M. hominis colonise?
Genital tract
Increases with sexual activity
What disease is caused by M. hominis?
Chorioamnionitis (pelvic inflammatory disease)
What diseases are caused by ureaplasma urealytium?
Postpartum and postabortal fever
Neonatal pneumonia
Bacteraemia
Abscesses
How is M. hominis diagnosed?
culture
PCR
How is M. Hominis treated?
Doxycycline
