Infections

Question 1

Surgical site infection -

Cause, organisms and Abx

Answer 1

Wound contamination.
Staph aureus. ?E coli, Pseudomonas, Haemolytic strep.
Flucloxacillin.

Question 2

Septic arthritis -

RF, presentation, Dx

Answer 2

Abnormal joint (RA), immunosuppression, bacteramia (DM, IVDU). 
Unwell, febrile, red hot swollen joint, usually knee, can't weight bear. 
Blood cultures before Abx. Asiprate joint (50,000 cells/mL), inflam markers. Imaging (effusion).

Question 3

Septic arthritis -

Bugs and Tx

Answer 3

Staph aureus 46%; Strep 22%; G- like E coli.

IV cephalosporin/fluclox.
MRSA: vanc.
Drain joint.

Question 4

Osteomyelitis

Answer 4

Local or haematogenous spread. Subacute Brodie abscess.
Pain, fever, local swelling.
MRI, bone biopsy.
Staph aureus.
Debride. Remove sequestra and infected bone.

Question 5

Prosthetic joint infection

Answer 5

Local from wound or systemic from UTI.
Staph, E coli.
Pain, joint failure, “joint was never right”.
Radiology: loosening. CRP mildly raised, some white cells in aspirate.
Replace joint again, use cement impregnated with Abx.

Question 6

Pyelonephritis Abx

Answer 6

IV, Broad spectrum,

eg. Co-amoxiclav + gentamycin.

Question 7

Define: Pyrexia of unknown origin

Answer 7

> 38.3 for 3 weeks, no Dx despite a week of intensive investigations

Question 8

Causes of classical PUO

Answer 8

• Infections
• Neoplasms
• Connective tissue diseases
• Undiagnosed conditions
• Abscesses, endocarditis, TB, complicated UTIs

Question 9

Causes of healthcare-associated PUO

Answer 9

• Surgery
• LRTI
• C diff
• IV line bacteraemia
• Drugs: vancomycin, serotonergics
• Immobilisation

Question 10

HIV-associated PUO

Answer 10

• Seroconversion
• TB / disseminated MAI
• PCP, CMV, cryptococcus, toxo, histoplasma
• KS
• Lymphoma

Question 11

PUO workup

Answer 11

Observe fever - try not to treat until cause known.
Take cultures before starting empirical Abx (even in neutropaenic sepsis) unless unstable.
Also:
- Vasculitis screen: pANCA, cANCA, Rho, La…
- Urine dip, Bence-Jones, casts
- Familial diseases eg. familial mediterranean fever, Fabry’s, cyclic neutropaenia
- Travel.

Question 12

Causes of fever in the returning traveller

Answer 12

• Malaria
• Dengue
• Typhoid
• Rickettsia
• Bacterial diarrhoea
• HIV seroconversion
• Viral haemorrhagic fevers.

Question 13

Clues to typhoid

Answer 13

Relative bradycardia, spleen, Rose spots.

Gallstones, immunosuppression.

Question 14

Signs of Malaria

Answer 14

Common: fever, spleen, nothing.
Rare: coma, shock, liver, focal neurology.

Question 15

Investigations for Malaria

Answer 15

Thick blood film: detect parasites. 
Thin blood film to tell species.
Various antigen tests. 
FBC: 70% low Plt, 30% anaemic. 
50% deranged LFTs.

Question 16

Malaria treatment

Answer 16

Mild:
Quinine + doxycycline
Severe:
Artemisin combination therapy

Question 17

Symptoms of Malaria

Answer 17

Fever + rigors, 
Flu-like, 
Headache, 
Back pain, 
Myalgia, 
N+V.

Question 18

Features of severe Malaria

Answer 18

Impaired consciousness,

Hb

Question 19

Rubella

Answer 19

DNA virus (togavirus)
Maculopapular rash - face then trunk = “three day measles”. Flu Sx. LNopathy.
20-50% sub-clinical.
Dx: serology on saliva.

Question 20

Congenital rubella syndrome

Answer 20

Infection before 10/40: deaf, retinopathy, cataracts, glaucaoma, heart disease, mental retardation.
Sometimes spontaneous abortion before 8/40.
No risk after 20/40.

Question 21

Parvovirus B19

Answer 21

Slapped cheek rash (erythema infectiosum).
Fever, malaise.
Transient aplastic crises, esp in Sickle and Spherocytosis.
Foetus before 20/40: 3% risk hydrops foetalis. Tx intrauterine transfusion. No risk after 20/40.

Question 22

Flu in pregnancy.

Answer 22

No congenital abnormalities,
but 5x stillbirth and 3x preterm delivery
(so vaccinate).

Question 23

Measles in pregnancy

Answer 23

IUD, miscarriage, preterm delivery, more maternal morbidity.