ID Flashcards
How can you distinguish between HIV dementia and Alzheimer’s disease?
Absence of higher cortical dysfunction such as aphasia, agnosia and apraxia, dysphagia help to distinguish from classical cortical dementia such as Alzheimer’s disease.
When are HIV infected patients at risk of OI and malignancy?
CD4 200-500: HZV, pneumococcal pneumonia, oral candidiasis, Tb
CD4 50-200: PJP, CNS toxoplasmosis, crytococcosis, kaposi’s sarcoma, NHL, PCNS lymphoma
CD4
Which haematology malignancy has the highest RF for developing invasive fungal infection?
AML Allogenic HSCT (part cord blood as source)
Which transplants have the highest risk fro developing fungal infections?
Heart, lung and liver transplant.
When is the Mantoux test considered positive?
> = 5 mm:
HIV or risk factors, close TB contacts, CXR evidence of TB.
=10mm
Indigent/homeless, residents of endemic Tb areas, residents of developing nations, IV drug use, chronic illness, NH, prisoners and health care workers
=15 mm for all other persons, BCG vaccination
How do you treat P. falciparum?
Riamet (Artemether and lumefantrine)
Malarone (Atovaquone + Proguanil)
Quinine sulphate + doxycycline
How do you treat severe malaria/chloroquinine resistant?
IV artesunate or
IV quinine
How do you Tx P. vivax, ovale, malariae?
Chloroquinine
Follow with 14 d course of primaquine for vivax and ovale
Exclude G6PD def prior to use of primaquine
MOA Artemether?
is metabolised to the active metabolite artenimol (dihydroartemisinin). Combination with lumefantrine acts in the food vacuole of the malaria parasite interfering with the conversion of haem to nontoxic haemozoin; also inhibits nucleic acid and protein synthesis.
How does Typhoid present (Salomella typhi)? Spread? Tx?
Clinical: Fever Abdo pain Constipation (not diarrhoea) Rose spots
Spread:
Faecal oral spread, usually water borne
Consider achlorydia in chronic setting
Tx:
Ciprofloxacin
Ceftriaxone
Azithromycin
Which organism is the likely cause of dental disease?
Strep viridans
Which organism is the likely cause of prolonged indwelling vas catheter and IVDU?
S. aureus
Which organism is the likely cause of procedures involving gut and perineum?
Enterococcus faecalis
Which organism is the likely cause of bowel malignancy?
Strep bovis
Which organism is the likely cause of soft tissue infection?
Staphlococci
Causes of culture negative endocarditis?
Coxiella brunette
Bortenella
Chlamydia
Legionella
What are the major and minor criteria for IE?
Dx criteria
2 major or 1 major + 3 minor or 5 minor
Major
1. +ve BC fro IE. Typical organisms growing in 2 cultures in absence of a primary focus
- ECHO evidence of mass, abscess, dehiscence
- Positive serological test fro Q fever
- New valvular regurgitation
Minor Fever>38 Vascular phenomena Immunoogoc phenomena Microbiological evidence Echo findings consistent with IE but not meeting the major criteria
What is the Tx for syphilis in patients with a penicillin allergy?
Doxycycline 100 mg PO BD
Are penicillins effective against Mycobacterium avium complex?
No
Increased number of which interleukins are associated with critical illness?
IL 6, 8, 15, interleukin 12p70
What are the histopathological changes associated with H1N1 virus infection?
varying degrees of diffuse alveolar damage with hyaline membranes and septal oedema, targets aleveolar lining cells (Type 1 and 11 pneumocytes) Tracheitis Necrotising bronchiolitis Pulmonary vascular congestion Alveolar haemorrhage
What is the explanation for the ability of the virus to cause severe viral pneumonitis in humans?
Ability to increase ex-vivo replication in human bronchial epithelium at 33C
What is the explanation for the ability of the virus to cause severe viral pneumonitis in humans?
Ability to increase ex-vivo replication in human bronchial epithelium at 33C
Which virus is responsible for (i) pandemics and epidemics, (ii) smaller localised milder outbreaks?
Influenza A
Influenza B
What is the pathophys of H1N1 virus?
The enzyme neuraminidase (N) present on the viral envelope facilitates cell penetration and the release of replicated viruses from the cell surface.
Influenza:
Localised outbreaks due to?
Epidemic and pandemic due to?
The annual influenza epidemics is best explained by which mechanism?
Localised outbreaks:
Antigenic drift in H and N influenza (local - A and B)
Epidemics and pandemics:
Antigenic SHIFT in H and N proteins (Influenza A).
What mechanism explains the new influenza A subtypes?
Antigenic SHIFT
List the gram +ve cocci
Staph
Enterococci
Strep
List the gram –ve cocci
Nessierua menin + gono
Moraxella
List the gram +ve bacilli (ABCDL)
Actinomyces Bacillus Clostridium Diptheria Listeria Remaining organisms are gram –ve bacilli (rods)
Which mutation in viral neuraminadase confers high level resistance to oseltamavir?
His275Tyr mutation
What is the likely cause of vancomycin resistance in enterococci?
Changes in cell wall to prevent binding
What is the mechanism of resistance of H. influenza?
production of beta lactamase
Do patients with a PFO require abx prophylaxis prior to Sx?
no
Which patients with cardiac conditions require IE abx prophylaxis before Sx ?
A prosthetic heart valve
Valve repair with prosthetic material
A prior history of infective endocarditis
Many congenital (from birth) heart abnormalities, such as single ventricle states, transposition of the great arteries, and tetralogy of Fallot, even if the abnormality has been repaired
What is the most common fungal infection in immunocompromised pts?
Candida
What is the mortality rate of invasive aspergillus infections in immunocompromised patients? What are the RF?
94% Neutropenia > 21d CMV GVH Corticosteroids RTx Diagnosis by PCR for Aspergillus. -ve pcr has high NPV
What is the Tx for MAC?
Ethambutol
Rifampicin
Clarithromycin
Do you get a rash with malaria?
no
When does the rash typically start for dengue?
3 days
Aetiology of dengue?
Flavavirus spread by the mosquito Aedes agyptii
Incubation of 3-14 d
What are the 3 syndromes of Dengue?
Classic
- abrupt fever, severe back pain, transitory maculopapular rash.
- defervescence and recrudescence of fever
Dengue haemmorhagic fever
- fever lasting 2-7 d
- hemorrhagic manifestation e.g. positive tourniquet test or spontaneous bleeding
- thrombocytopenia, Plts
What is the Mx of dengue?
Supportive
What are the lab findings for Dengue?
- neutropenia
- thrombocytopenia
- increased transaminases
- diagnosed by dengue serology (4 x rise in antibody titre over 2 weeks)
Main causes of fever in a returned traveller?
Dengue - rash
Malaria - no rash
Typhoid (S. typhi) - a type of enteric fever along with paratyphoid fever
Aetiology of Malaria?
Transmitted by female mosquito
P. falciparum- most common, most severe and highest mortality P. vivax P. ovale p. malariae - benign P. knowlesi - hyperparasitemia
How do you Dx Malaria?
Thick and thin films
Immunochromatographic test (ITC)
Antigen capture test - rapid diagnosis. High sensitivity for P. falciparum if > 100 parasites/uL
haemolytic anaemia
What is the Tx for P. viviax, oval and malaria?
chloroquine/hydroxychloroquine
Primaquine as anti-relapse therapy for 14 days after chloroquine
Tx for P. vivax chloroquine resistant?
Riamet (Arthemether-lumafantrine) 1st line in Indonesia, Timor, PNG, Solomon island and Vanuatu
What is the Tx for P. falciparum?
1st line- Riamet (Arthemether-lumafantrine)
2nd line - Malarone (Artovaquone and Proguinil)
3rd line - Quinine and doxy
What is the Tx for severe Malaria (jaundice, reduced LOC, anaemia, pulmonary odema, hypoglycaemia))?
IV artesunate
What is the Tx for malaria in pregnancy?
quinine and clindamycin
Chemoprophylaxis for Malaria (chloroquinine resistant or sensitive)?
Chloroquinine sensitive, use chloroquinine
Chloroquinine resistant, use atovoquone and proguinil
How do you Dx Schistosomia haematobium? What is it?
Trematode, found in Africa or middle east.
Eosinophilia - hallmark of disease
Stool culture - ova detected (at 40-50d of infection)
Urine culture - ova detected (at 40-50 d of infection)
Clinical presentation of Schistosomia haematobium?
fever chills cough urticarial rash hepatomegaly lymphadenopathy haematuria
Tx of Schistosomia haematobium?
Praziquantel
What causes Leptospirosis? How does it present? Dx? Tx? Complications?
Spirochete leptospira interrogans
fever, chills, myalgia, diarrhea, conjunctival suffusion
Dx- leptospira serology
Tx- amoxycillin, doxycline or Ceftriaxone
Complications- hemorrhage, jaundice, acute renal failure, aseptic meningitis
What is the most common cause of diarrhoea in an adult traveller to a developing country?
Enterotoxigenic E. coli (ETEC)
40-70% of traveller’s diarrhoea
Causes of watery diarrhoea?
ETEC
Vibrio cholera
Viral
Causes of bloody diarrhoea?
Shigella
Slamonella
Campylobacter
Entameba histolytica
Causes of prolonged diarrhoea?
Giardia
Crypto
What is the Tx of traveller’s diarrhoea, mild and mod?
Mild - fluids +/- loperamide
Mod- single dose azithromycin or single dose oral norfloxacin