Investigation of specific infections Flashcards
Meningitis Investigation
Lumbar Puncture (LP) to collect Cerebrospinal fluid (CSF)
- Blood cultures (2 sets)
- Blood for bacterial PCR (S. pneumoniae and N. meningitidis)
- FBC, Clotting, U & E’s, LFT’s, Glucose, CRP
Encephalitis Investigation
- CSF requesting viral PCR specifically
Brain Abscess Investigation
- Local Sampling:
Pus: surgical biopsy/drainage = Gram, culture, sensitivity (PCR)
Ear – Acute Otitis Media Investigation
- Send pus if ear drum perforated
Ear – Acute Otitis Externa Investigation
- Ear swab: determine cause and sensitivity
Nose – Rhino-sinusitis (sinusitis) Investigation
Sample pus from operative sinus lavage (washing out sinus)
- FBC, Blood cultures in severe cases only
Throat – sore throat (pharyngitis) Investigation
- Send throat swabs only if evidence bacterial infection Additional tests: - EBV serology - Swab for Diphtheria - Pus if Quinsy abscess
Influenza Investigation
- Nose/ throat swabs – immunofluorescence
- PCR (sensitivity >90%, specificity 99%)
Pneumonia Investigation
- Severity assessment: CURB65 score
- Score of 2-5 (mod-sever) – sputum, blood cultures, atypical screen
Pulmonary TB Investigation
- Exposure testing – Mantoux, Interferon Gamma Releasing Assay
- If pulmonary symptoms – 3 sputum samples, microscopy/culture – 8 weeks, PCR
Localised skin infections Investigations
- Impetigo, erysipelas, cellulitis
- Wound swabs
- Needle aspirates from cellulitis
- Blood cultures – only positive in most severe 5%
Necrotising Fasciitis
Investigation
- Debride (remove) tissue - microscopy, cultures and sensitivity
- Blood cultures – 2 sets
- Bloods; FBC, U&Es, LFTs
Diabetic foot infection Investigation
- Mild infection – wound swabs
- Moderate-severe infection – debride (remove) white macerated wound and collect clean bone/tissue sample
Lower UTI – cystitis, upper UTI – pyelonephritis Investigation
- If dysuria and frequency, then 90% UTI
- Urine sample – WBC, RBC, epithelial cells, bacterial growth, sensitivities
- Kass criteria – threshold for “significant bacteriuria”
UTI – Prostatitis Investigation
Urine mainstay of investigation – post prostatic massage
UTI – Epididymo-orchitis Investigation
- Urine – cultures
- Urine – chlamydia and gonorrhoea NAAT
- If severe – bloods, blood cultures, USS +/- drainage
Infectious diarrhoea Investigation
- Stool sample taken (for parasites – need 3 stool samples)
- Bloods, blood cultures
- Abdo imaging
Helicobacter Pylori Investigation
- Antibody test - insensitive
- Stool antigen
- Urea breath test - gold standard for test of cure
- Biopsy urease test
- STOP PPIs (Proton pump inhibitors – antiacids; reduce stomach acid) BEFORE TESTING
Liver abscesses Investigation
- Pus sample
- Stool for OCP
- Blood cultures
- FBC, U&Es, LFTs, CRP
- Hydatid serology
- Imaging – USS, CT
Cholangitis/ cholecystitis Investigation
- Bloods – FBC, U&Es, LFTs, clotting, amylase
- Blood cultures
- Imaging – USS or CT
- Bile fluid or pus
Complicated Diverticulitis Investigation
- Pus from abscess
- Blood cultures
- FBC, U&Es, LFTs, clotting, amylase
- CT
Endocarditis Investigation
- THREE SETS OF BLOOD CULTURES – AT DIFFERENT TIMES during first 24hrs of suspected EC
- Bloods, cultures, microscopy
- Trans-thoracic Echo (TTE)
- Trans-Oesophageal Echo (TOE)
Vascular graft infections Investigation
- Three sets of blood cultures at different times
- CT, PET – scan fluids around graft/fistulae
- Tissue/ fluid from around graft for culture or PCR
Viral Hepatitis A, B, C Investigation
- Serology – antigen AND antibody detection
- PCR - presence of DNA/RNA = active infection
- Hep A – IgM (short term) and IgG (longer term) tested
- Hep B - acute infectious period followed by chronic period
- Hep C – only use IgG testing
Syphilis Investigation
- Detection by PCR (superseded dark ground microscopy)
- Serology: IgM in primary infection, treponemal specific antibody
