Infection Flashcards
How is HAP defined?
> 48hours since admission
What are the bacterial causes of pneumonia?
Streptococcal- COMMONEST Moraxella HiB Mycoplasma Legionella Klebsiella Chlamydia pneumonia/psittaci TB Pneumocystis jiroveci (HIV)
What viruses can cause pneumonia?
Influenza
Measles
VZV
What fungi can cause pneumonia?
Aspergillus
Candida
What are the commonest causes of HAP?
Staph Aureus
Gram -ve
What are the typical features of pneumonia?
Pleuritic chest pain Productive cough Dyspnoea Fever + rigors I/L Dull percussion Bronchial breathing Coarse crepitations ↑Tactile fremitus I/L
How is pneumonia investigated?
Bloods: FBC, Blood cultures, U&E, CRP ABG if sats <92% Sputum MC&S CXR: Consolidation Serology/PCR: Mycoplasma + Chlamydia Urine Ag: Legionella CURB65
What does CURB65 stand for? What do the scores correlate to?
Assesses severity & determines management: C: Confusion- AMTS <8/10 U: Urea- <7 R: RR >20 B: sBP <90 65: >65yo
0-1 = Mild (manage at home) 2 = Moderate (admit) >3 = Severe (ITUw/ IV Abx)
In pneumonia what does the colour of the sputum correlate to?
Rusty colour = Strep
Green/yellow
Black = Pneumoconiosis
How is pneumonia caused by Aspergillus treated?
Aflatoxin
How is a mild pneumonia treated?
Amoxicillin 500mg TDS for 5 days
Pen allergic: Clarithro/Doxy
How is a moderate or severe pneumonia treated?
Amoxicillin 500mg TDS + Clarithromycin (Macrolide) for 7-10days
CURB >3 = Co-Amoxiclav
How would an atypical pneumonia be treated? Why?
Macrolide OR Fluoroquinolones- Both act intracellularly:
<5d since admission: Co-Amox/ Cefuroxime
>5d since admission: Tazocin/ Cefuroxime
When in pneumonia would you consider a change in antibiotic?
Failure of ↓CRP in 72hours = Treatment Failure
What are the indications to not discharge a patient following pneumonia?
In PAST 24hrs pt has 2 of:
- Temp >37.5
- RR >24
- HR >100
- sBP <90
- O2 sats <90% ORA
- Inability to eat/drink without assistance
- Abnormal mental status
Is any follow-up required in pneumonia?
CXR at 6w
Which groups are at high risk of pneumonia caused by Klebsiella?
Alcoholics
Diabetics
Which groups are at high risk of pneumonia caused by pseudomonas?
Bronchiectasis
HAP (ITU post-surgery)
CF
What are the signs of pneumonia caused by Legionella?
Flu-like dry cough SOB HIGH fever HAEMATURIA Diarrhoea & vomiting Hepatitis Renal failure Confusion Coma
What are the complications of pneumonia?
T1RF Pleural Effusion Lung abscess Sepsis/Septicaemia Empyema AF HypoT
What is a pleural effusion?
Accumulation of fluid in pleural cavity
What is an empyema?
Pus (pH <7.2) in the pleural cavity
What are the 2 types of pleural effusion?
Transudative: <25g/L Protein
Exudative: >35g/L Protein
What are the causes of a transudative effusion?
↑hydrostatic (force of blood on vessel wall) ↓Oncotic pressure (↑solute in pleural space) HF/CCF Fluid overload Constrictive pericarditis PE Nephrotic syndrome Cirrhosis Malabsorption
What are the causes of a exudative effusion?
↑permeability of pleural surface +/- capillaries due to inflammation:
Infection – pneumonia, TB Infarction – PE
Inflammation – SLE, RA, pancreatitis
Malignancy– Lymphoma, mesothelioma, bronchial SCC, Mets – lung & breast
If someone had a chylothorax what differentials would you be worried about?
Lymphoma
Sarcoidosis
Amyloidosis
Cirrhosis
How is a pleural effusion investigated?
CXR Bloods: FBC, LDH & total protein USS guided aspiration LIGHT'S CRITERIA Percutaneous pleural biopsy Bronchoscopy
What should be commented on/tested when assessing a pleural aspirate?
Appearance: Clear/turbid/purulent/haemorrhagic
Odour
Protein: >35 = E, <25 = T, 25-35 = Light’s criteria
Cytology: Neut/Lymph/Mesothelial cells, giant multinucleated cells
Glucose: <3.3 = TB, RA, SLE, Malignancy, empyema
pH: <7.2 = CHEST DRAIN
LDH: Light’s criteria
Amylase: Raised
Immunology: RF, ANA, Complement
What is Light’s criteria?
Distinguish between transudative & exudative effusion
EXUDATIVE if one of:
- Pleuritic fluid protein/serum protein = >0.5
-Pleural LDH/Serum LDH = >0.6
-Pleural LDH >2/3rd upper limit of normal of serum LDH
How is a pleural effusion managed?
1) Chest drain
NEVER drain >1.5L = Pulm Oedema
2) Pleurodesis w/Tetracycline or talc if recurrent effusions
What condition needs to be considered in a female w/ a R pleural effusion?
Meig’s Syndrome:
- Ovarian fibroma
- Hypothyroid
- Ascites
- R pleural effusion
How does TB cause a systemic infection?
1o/LATENT: Macrophages in alveoli engulf bacteria + transport to Hilar LN to control spread
Some bacteria disseminates via lymphatics/blood to distant sites + small granulomas form around bacterium in body (lungs, kidney, spine, adrenals)
80% cases spont heal or encapsulate (fibrosis + calcification) and lie dormant (ghon focus)
2o/ACTIVE: When malnourished/ immunoS/elderly, Ghon focus reactivates
Spreads to lung apex (high O2 area)
Memory T-cells release +++ cytokines
Caseous necrosis & cavitation
TB disseminates via pulmonary venous system = systemic Miliary TB
How does primary TB present?
Asymptomatic
Fever/pyrexia of unknown origin
↓Weight/anorexia/FTT
Malaise/fatigue
How does secondary TB present?
60% Pulmonary: Chronic productive cough Purulent/blood-stained sputum Dyspnoea Palpable LN Night sweats + rigors
GU- commonest site outside of lungs: Sterile pyuria/haematuria Dysuria Loin pain Infertility (F) Swollen epididymis (M)
How is primary TB investigated?
1) Mantoux test: Tuberculin skin injection
<6mm = -ve
6-15mm = +ve (may be due to past infection)
>15mm = +ve (Highly suggestive of TB infection)
2) Interferon-gamma test
3) PCR
How is secondary pulmonary TB investigated?
PULMONARY:
1) CXR
2) Sputum sample x3: For MC&S, Ziel-Neelson stain
3) Bronchial lavage sample via bronchoscopy: if no sputum
What is seen on a CXR of someone with TB? What do each of these signs tell you?
I/L Hilar lymphadenopathy (Ghon focus) = 1o
Apical consolidation = 2o
Cavitating lesion = 2o
Reticular pattern/milliary lesions = 2o
Fibre-Calcification → Tracheal shift toward Miliary lesion
How is secondary GU TB investigated?
1) Urine MC&S
2) Early morning urine sample x3
3) Renal USS
How does secondary MSK present & how is it investigated?
Pain/Arthritis Osteomyelitis Abscess formation: Loin/psoas/spinal Nerve root compression Post disease (Infection of lumbar spine)
Ix: MRI/CT spine
How does secondary CNS present & how is it investigated?
TB meningitis Fever Headache Vomiting Abdo pain Drowsy/delirius Cranial nerve palsy/tremor
Ix:
LP = Fibrin web, mononuclear cells, ↓G, ↑P
CT/MRI head = Signs of ↑ICP
How does secondary Skin present?
Erythema Nodosum
Lupus Vulgaris: Face/neck
How does secondary Cardiac present & how is it investigated?
Pericardial effusion
Constrictive Pericarditis
Ix: ECHO
How is latent TB managed?
Rifampicin + Isoniazid = 3m
OR
Isoniazid = 6m
How is active TB managed?
RIPE Abx for 2m: R: Rifampicin 3/w I: Isoniazid 3/w P: Pyrazinamide 3/w E: Ethambutol 3/w CONTINUATION PHASE: Abx x2 for 4m: Rifampicin + Isoniazid
What is given in addition to Abx in TB meningitis treated?
Dexamethasone
CONTINUATION PHASE = 1yr
What TB prophylaxis can be given?
BCG vaccine: <35yo + at risk
Abx to close contacts: Rifampicin/Isoniazid for 6m or both for 3m
