Flashcards in L9 - Gram negative Cocci, mycobacteria Deck (17)
What do you call an unexplained fever?
Pyrexia of unknown origin (PUO)
What are typical causes of PUO?
Autoimmune issues (24%)
None found (18%)
What are some zoonotic causes of fever?
Brucella, Q fever and Toxoplasma
When do you usually get infected with TB and when does disease normally manifest?
Usually infected in early childhood in a developing country
5% clinical disease within first year
2.5% in the second year
2.5% residual life time risk of re-activation
Which populations have high TB progression rates?
Where is the initial site of infection and where does it progress to?
Drains to regional lymph node where it calcifies and forms a Ghon complex
Post-primary disease occurs in the upper lobe
What do you do to diagnose TB?
Early morning sputa for three days, takes a long time to grow cultures though
Use mantoux/Quantiferon gold for exposure
What do you use to treat TB?
Combination of four drugs for six months if has a sensitive disease: (RIPE) Rifampicin, Isoniazid, Pyrazinamide and Ethambutol
Quinolones, macrolides, streptomycin used for resistant strains
What is the relationship between TNF-inhibitors and TB recurrence?
TNF is a major mechanism in killing of TB. inhibitors, used to treat rheumatoid arthritis, impair macrophage killing and so increase the likelihood of TB recurrence
How is TB transmitted?
Airbone. Droplet is only 1-5um, so stays in the air for long periods of time.
What is the 'most important' disease involving fever and a rash?
Describe the rash usually seen in patients with meningococcal disease
Puerperic rash, with big blobs of bleeding under the skin. Will also feature perticei, tiny purple spots which are from fragile capillaries bleeding
Describe the gram stain appearance of Neisseria meningiditis
Gram negative, diplococci. They are kidney bean shaped
Describe meningococcal pathogenesis
Initially colonises the nasopharynx - 5-20% of the population.
In a very small percentage, bacteria cross the mucosal barrier and cause bacteraemia. Once in the blood stream, patients may get septicaemia (20% mortality) or meningitis (5% mortality).
Prevention of intravascular survival of bacteria by complement system.
There is then opsonisation of opsonised organisms in spleen
Who is at 800 fold increased risk of Meningococcal?
Household contacts/kissing cousins of someone who is infected
Describe Meningococcal onset
Nonspecific: fever, muscle or joint aches, Rubelliform rash - 7-12 hours onset (median)
This progresses to a petechial rash, neck stiffness, photophobia, vomiting and drowsiness - median onset 13-22 hours