General ID Flashcards
What factors affect Abx choice?
Patient- immunocompromised, allergies, drug interactions, compliance
Disease- Type of infection, previous M/C/S, known local pathogens and resistance, severity (ie PO vs IV), community vs hospital acquired
Hospital- Local protocols and guidelines
Which disease typically show pulse-temperature dissociation (ie relative bradycardia with raised temp)
Enteric fever
- Typhoid and Paratyphoid
Ebola virus disease
What is the stereotypical test for S. typhi in suspected typhoid fever?
Widal test
Immunoassay for Anti-S. typhi antibodies
Good in returned travellers, limited utility in endemic regions as cannot distinguish between current and previous infections
What are the typical tests to assess for Malaria?
- Thick/Thin blood smear (assess presence of parasite and what type)
- Blood film (assess for schistocytes)
- Malarial PCR
What is the empiric therapy for severe malaria?
Artesunate 2.4mg/kg IV or IM
What is the most common cause of diarrhoea in AIDS patients?
Cryptosporidium
However typical and very atypical organisms can also be the cause, need stool and blood cultures
What are the relevant points on history with occupational needle exposure?
- Was the skin breeched
- Was there visible bleeding
- Had the needle been used on a patient? was it visibly contaminated?
- Was the area immediately washed with soap and water
- Is the staff member vaccinated against Hep B and do they have appropriate antibody titres
- Is the source known to have HIV, Hep B or Hep C? are they likely to have it (sex worker, IVDU etc)?
What are the risk factors for an epidural abscess?
- IVDU
- Anything procedure causing bacteraemia (dental procedures, infected catheters, tatooing, acupuncture etc)
- Infective IE
- Lumbar puncture/epidurals or paraspinal steroid/anaesthetic injections
- Recent spinal surgery
- Diabetes
- Alcoholism
- HIV infection and any form of systemic immunocompromisation
- Trauma to the spine
- Infection near the site ie spine osteomyelitis, cellulitis over spine
What are the most common bacterial causes of epidural abscess
Staph aurea (63%)
Mycobacteria in resource poor areas
strep species
Gram -ve bacilli
What is the cross reactivity between penicillins, cephalosporins, carbapenems and monobactams?
- The cross reactivity is related to similar side chains and not a class effect (ie beta lactam core)
- For penicillins/cephalosporins with no similar side chains the cross reactivity is approx 1%, but closer to 40% if the side chains are similar.
- 3rd/4th/5th generation cephalosporins have the least cross reactivity with penicillins and vice versa
- Carbapenems as a group have <1% to close to 0% cross reactivity with other beta lactams
- Monobactams have no cross reactivity with other beta lactams
When should cephalosporins and carbapenems be completely disregarded as an option with a history of penicillin allergy?
- If the patient has a history of a serious Typle II/III/IV reaction
Serious type II (IgG mediated cell destruction)
- Haemolytic anaemia, neutropaenia, thrombocytopaenia
Serious type III (immune complex deposition, complement activation)
- serum sickness, drug induced vasculitis/nephritis
Serious type IV (T cell mediated)
- SJS/TEN, DRESS
Type I (IgE mediated)
- Anaphylaxis has less cross reactivity and wanes over the years (80% allergy resolved within 10yrs)
What is the typical adult regime for HIV PEP in Australia?
Tenofovir/Emtricitabine (Truvada) 300/200mg
PO daily
+/-
Dolutegravir 50mg PO daily
Continue for 28 days until GP/ID review
What is the dosing of Hep B immunoglobulin for PEP?
<30kg = 100 IU via IM route
or
>30kg = 400 IU IM
within 14 days of exposure
What is the indication for Hep B immunoglobulin in occupational exposure?
Known to be unimmunised
or
Hep B surface antibody titre <10IU
What are the most common causes of fever in a returned traveller?
Malaria
Dengue fever
Enteric fever (typhoid/paratyphoid)
Mononucleosis
HIV
Rickettsial infection
- Sub-Saharan Africa
Melioidosis
- North australia, southeast asia
Trypanosomiasis
- Africa
Leptospirosis
Japanese encephalitis
Influenza
Covid 19
CAP
MERS-Cov
- Arabian peninsula
Tuberculosis
- At least 3 month incubation
What are the key elements in a travel history?
When are children with measles considered to be infection from?
4 days prior to rash to 4 days after the onset of the rash
What are the features an specifics of VZV primary infection?
- Transmission via resp droplets and direct contact
- Incubation is 10-21 days
- Patient is infectious from 1-2 days prior to rash until all lesions are crusted over (usually day 5-6)
- Complications include pneumonia, shingles, neurological sequelae, secondary bacterial/HSV infection
When is VZV immunoglobulin recommended for primary infection?
- Up to 10 days post exposure
- special groups ie immunocompromised, pregnant women, neonates and premature infants
What is the initial management of a staff member with a needle stick injury?
What is the management and investigations for staff with needle stick injuries who aren’t immunised against Hep B?
What is the estimated risk of transmission of HepB/C and HIV with needle stick injuries?
What are the Duke Criteria for infective endocarditis?
Major
- Blood cultures x2 positive for typical endocarditis MO’s
- Evidence of endocardial involvement ie new murmur, +ve TOE or TTE
Minor
- Fever
- Predisposing heart conditions or injection drug use
- Vascular phenomena (strokes, bleeds, mycotic anuerysms, janeway lesions, petechiae, splinter Hx etc)
- Immunological phenomena (oslers nodes, Roth’s spots, GN, RF +ve)
- Evidence of infection (+ve inflammatory markers, +ve blood cultures but not major criteria etc)
What are the RF’s for IE?
- Age >60
- Male sex (3:2)
- IVDU
- Poor dentition/Dental infection
- Any structural heart disease
- Rheumatic heart disease
- Previous IE
- Indwelling vascular device
- PPM/ICD in situ
- Long term haemodialysis
- Cardiac bypass surgery
- HIV infection
What are the most common MO’s for IE?
- Staph aureus (31%)
- Strep Viridans (19%)
- Staph epidermidis (11%)
- Enterococci (11%)
- Strep Bovis (7%)
- HACEK (2%)
HACEK organisms
- Haemophilus aprophilus
- Actinobacilus sp
- Cardiobacterium hominis
- Eikenella corrodens
- Kingella Kingae
What is the typical dosing of meningitis prophylaxis for close contacts?
Confirmed N. meningitidis
- Ciprofloxacin 500mg PO daily
Confirmed H. influenzae
- RIfampicin 20mg/kg (max 600mg) PO daily
What is the empiric therapy for Infective Endocarditis before M/C/S is back?
Native Valve
- Benpen QID 60mg/kg (max 2gm)
- Fluclox Q4-6 50mg/kg (max 2gm)
- Gentamicin 7.5mg/kg
Artificial valve, post surgery, MRSA and IVDU
- Vancomycin 20-30mg/kg IV as loading dose
- Fluclox Q4-6hr 50mg/kg IV
- Gentamicin 7mg/kg IV, 4-5mg/kg IV if patient has renal failure
What are the risk factors for Listeria monocytogenes infection (ie meningitis)?
- Neonates
- > 50yo
- Immunocompromised
- Pregnant
- Debilitated
- Hazardous alcohol consumption
Treatment is with benzylpenicillin 1st line
2nd live if allergy is Bactrim
What are the different categories of severity for covid 19?
Mild
- Not requiring 02
- No lower respiratory tract disease
- Overall mild symptoms
Moderate
- LRTI symptoms BUT no 02 requirement (>92% RA)
- Mild to moderate symptoms
Severe
- Requires 02 (sats <92% RA) BUT no mechanical ventilation
- Infiltrate >50%, RR >30
Critical
- Requiring invasive ventilation
- May have multi-organ failure, ARDS, ECMO etc
What are the specific issues with overprescribing of antibiotics?
- Side effects
- Resistance
- Drug interactions (ie warfarin)
- Overall cost
- 2ndary infections ie C. difficile
- Alteration of persons microbiome
