Infectious Diseases Flashcards
What organism causes Rheumatic fever?
Group A streptococcus
What are the major features of acute rheumatic fever?
- Carditis
- Poly arthritis
- Chorea - abnormal mvmt
- Subcutaneous Nodules
- Erythema Marginatum
What is the treatment for ARF?
- single dose benthazine penicillin or 10 days penicillin oral
- arthritis/fever - paracetamol or aspirin/naproxen once diagnosis confirmed
- carditis HF - bed rest, diuretics and restrict fluids
What is the vegetation in endocarditis? where are they most common?
(1) endothelium damage leads to platelet-fibrin deposition
(2) trauma and bacteraemia
both lead to adherence, colonisation and a mature vegetation
commonly aortic or mitral
What are high risk cardiac lesions that increase the chance of vegetations?
- Prosthetic heart valves
- Cyanotic congenital heart disease
- Previous infective endocarditis
- Mitral valve prolapse with significant regurgitation
What is the progression of infection that leads to heart failure?
- Infection spreads from base of vegetation forming abscesses
- Valve failure - perforation of leaflets and chord tendinae rupture
- Heart failure secondary to severe regurgitation
What are some classical features of endocarditis?
- Splinter haemorrhages
- sub-conjunctival haemorrhages
- Clubbing of the fingers
- Splenomegaly
- Osler’s Nodes
- Janeway lesions
- Roth spots
What investigations are required for a definitive diagnosis of endocarditis?
Routine blood tests - CRP/ESR Urine sediment Cxr ECG Echocardiography
Common causes of infectious rhinitis, pharyngitis and layrngitis
Rhinitis - adenovirus, rhinovirus
Pharyngitis - RSV, influenza, staph aureus, beta haemolytic strep
Laryngitis - RSV, H influenza, beta haemolytic strep
Routes of infection in respiratory tract infection
- aspiration
- inhalation
- haematogenous
Normal defence mechanisms of resp tract
- mucocilliary apparatus
- intact epithelial surfaces
- alveolar macrophage/inflammatory cells
How might pneumonia be classified?
Aetiological agent: strep pneumoniae, H influenza, moraxella catarrhalis, mycoplasma
Pathological/anatomical: lobar, bronchopneumonia
Syndromes: CAP, HCA, HA, chronic, necrotising and lung abscess
Bacterial cause of community acquired pneumonia
- strep pneumoniae
- haem influenza
- mortadella catarrali
- staph aureus
- klebsiella pneumoniae
- pseudomonas pneumoniae
- legionella pneumoniae
4 Stages of inflammatory response in acute bacterial pneumonia
- congestion - lung is heavy and boggy
- red hepatisation - firm, red, airless, exudate of RBC
- grey hepatisation - grey brown and dry lungs, persistence of fibrin and neutrophils
- resolution - exudate undergoes enzymatic digestion and debris absorbed
Atypical community acquired pneumonia causes
How do they manifest?
- mycoplasma pneumoniae
- influenza
- adenovirus
- rhinovirus
- VZV
- Chlamydia pneumoniae
May present as severe URTI, varied features
Health care associated pneumonia causes
- MRSA
- P. aeruginosa
Hospital acquired pneumonia causes
- enterobacteriaecea
- pseudomonas spp
- MRSA
- Strep pneumoniae
Which type of pneumonia is commonly polymicrobial?
Aspiration - often from gastric contents
Often causes necrotising pneumonia with abscess
Causes of pneumonia in immunocompromised host
- pseudomonas aeruginosa
- mycobacterium
- legionella listeria monocytogenes
- herpes
- CMV
Common agents of chronic pneumonia
- bacterial Mycoplasma tuberculosis
- actinomycetes
- nocardia
- fungal
What is primary, secondary, progressive and milliary tuberculosis?
Primary: inhaled bacilli implant and Ghon Focus forms, 95% of the time CMI controls it
Progressive primary - massive haematogenous dissemination
Or can remain latent until secondary TB
Secondary: apical consolidation, progressive fibrosis
Progressive pulmonary TB: expanded area of caseation, erosion into airway creates cavity
Milliary: systemic/pneumonia
HACEK organisms
Haemophilic parainfluenza Aggregatibacter actinomycetemcomitans Cardiobacterium hominis Eikenella corrodes Kingella Kingae
Common causes of bacterial endocarditis
- streptococci viridans
- Staph. aureus
Subacute and acute presentation of bacterial endocarditis
Subacute - weeks of low grade fever, anaemia, weight loss
Acute neurological event - CVA, meningitis, toxic encephalopathy
Classical features of bacterial endocarditis
- splinter haemorrhages
- clubbing
- splenomegaly
- Osler’s nodes
- Janeway lesions - palms/soles
- roth spots - eyes
Duke’s criteria for definitive diagnosis of endocarditis
2 major criteria: + blood culture for infective endocarditis, and evidence of endocardial involvement
OR 1 major and 3 minor OR 5 minor
Minor criteria: predisposition, fever, vascular phenomenon, immunologic phenomena, ECG, microbiological evidence
Empiris bacterial endocarditis treatment for native and prosthetic valve:
Native: IV ben.pen, + IV fluclox, + IV gentamicin
Prosthetic: IV vancomycin + IV gentamicin
Rheumatic fever
Post infectious immune mediated disease 2-4 weeks after GAS pharyngitis
Modified Jones criteria for RF
MAJOR Carditis Arthritis Subcutaenous nodules Syndenhams chorea Erthema margintum MINOR: arthralgia, fever, elevated ACP, evidence of GAS on culture, prolonged PR, previous ARF ---- NEED: 2 major or 1 major + 2 minor
Typical and atypical symptoms of pneumonia
Typical: fever, chills, cough, chest pain
Atypical: myalgia, arthralgia, headache, GI
Physical examination of pneumonia
- tachycardia
- elevated RR
- reduced O2 saturation
- reduced air flow in affected lung
- added sounds - crepitations etc
3 components in diagnosis of pneumonia
- blood test - FBC, inflamm markers, blood culture
- Radiology - CXR, CT
- Microbiological - sputum gram stain and culture, serological for antibodies 4x rise in IgM, and molecular like throat swab for PCR
Treatment for mild CAP
Amoxicillin oral
- use doxycycline or clarithromycin if atypical suspected
Treatment of moderate CAP
IV penicillin (ceftriaxone if allergy) - oral doxycycline/clarithromycin if atypical suspected
Treatment of severe CAP
IV ceftriaxone or penicillin
+ Azithromycin to cover atypical
+ Gentamicin often added IV
Treatment for aspiration pneumonia
IV metronidazole
Tazocin covers all
Health care associated pneumonia treatment
IV pipericillin-tazobactam (tazocin) OR IV cefepime
AND
IV gentamicin + IV vancomycin if MRSA suspected
