Infectious diseases Flashcards
What is Lemierre’s syndrome?
Jugular vein suppurative thrombophlebitis
Think in bacteraemia with Hx of pharyngitis and unremitting fever
Which organism often causes infection following fresh water exposure?
Pseudomonas aeruginosa
What does a positive HBsAg suggest?
Hepatitis B surface antigen
Suggests active infection, acute or chronic
What does a positive anti-HBs suggest?
Hepatitis B surface antibody
Suggests life-long immunity, either resolved infection or vaccination
What does positive anti-HBc IgM suggest?
Current infection
Positive 4-8 months after infection
What does a positive anti-HBc IgG suggest?
Resolution of acute infection
OR chronic infection (does not confer immunity)
How do HBsAg levels change over time?
Positive: 2-10 weeks after infection
Negative: 4-6 months after infection (positive anti-HBc may be the only marker of acute infection)
Positive: > 6 months after infection (signals chronic infection)
What does HBeAg reflect?
Marker of viral replication
Marker of infectibility/transmission
An abrupt onset of fever + rash + severe arthralgia and myalgia is characteristic of which disease?
Dengue fever
How is dengue fever transmitted?
Mosquitos
Most commonly in the tropics and subtropics
Fever + bradycardia + jaundice + bleeding is characteristic of which condition?
Yellow fever
What occurs once yellow fever progresses to severe disease?
Jaundice
Renal failure
Hepatic failure
Haemorrhagic complications
How is syphilis diagnosed?
- Non-treponemal test (non-specific anticardiolipin antibodies)
- Followed by confirmation with a treponemal test (detects treponemal antibodies)
OR
Direct detection of the pathogen (dark field microscopy, PCR)
What are two examples of a non-treponemal test?
Rapid plasma reagin (RPR)
Venereal disease research laboratory (VDRL)
Screening tool, can evaluate disease activity, monitoring response to treatment
What is an example of a treponemal test used for the diagnosis of syphilis?
Treponema pallidum particle agglutination (TPPA)
Fluorescent treponemal antibody absorption test (FTA-ABS)
When is direct detection of the pathogen by either dark field microscopy or PCR used for syphilis diagnosis?
When a sample can be obtained e.g., exudative chancre, condyloma
May be the only positive test in early primary syphilis
Which drugs are used for active TB?
2 months of daily
- Rifampicin
- Isoniazid
- Pyrazinamide
- Ethambutol
Followed by 4 months of daily
- Rifampicin
- Isoniazid
How is latent TB treated?
Isoniazid for 6-9 months
Decreases risk of progression
Eliminates risk of transmission
How is a diagnosis of clostridium difficile confirmed?
Detection of toxins in stool (enzyme immunoassay)
Or PCR OR EIA for C. difficile glutamate dehydrogenase antigen
From what species of parasite is malaria contracted?
Plasmodium
What type of mosquito carries malaria?
Anopheles
Which parasite causes the most severe form of malaria?
Plasmodium falciparum
Which medications are used to treat malaria?
Artemether + lumefantrine
