Infectious Diseases Flashcards
(207 cards)
1
Q
Definition of pneumonia
A
Infection of lung tissue causing inflammation and sputum filling the airways and alveoli.
2
Q
What are the types of pneumonia
A
- Community Acquired Pneumonia (CAP)
- Hospital Acquired Pneumonia (HAP)
- Aspiration pneumonia
- Atypical pneumonia
3
Q
Symptoms of pneumonia
A
- SOB
- cough with purulent sputum
- fever
- haemoptysis
- pleuritic chest pain
- delirum
- sepsis
4
Q
Signs of pneumonia
A
Characteristic chest signs
* bronchial breath sounds = harsh breath sounds due to consolidation
* focal coarse crackles = air passing through sputum
* dullness to percussion - lung collapse &/or consolidation
Sepsis secondary to pneumonia
* tachypnoea
* tachycardia
* hypoxia
* hypotension
5
Q
How is the severity of pneumonia assessed?
A
CURB-65 (CRB-65 out of hospital)
* Confusion: abbreviated mental test ≤8 or disorientated
* Urea >7
* RR ≥ 30
* BP: SBP <90 or DBP ≤60
* Age ≥65
0-1 = mild, consider treatment at home
≥2 = moderate, consider hospitalisation
≥3 = severe, consider intensive care assessment
6
Q
Common bacterial causes of pneumonia
A
- streptococcus pneumoniae (50%)
- haemophilus influenzae (20%)
7
Q
Other bacterial causes and associations of pneumonia
A
- moraxella catarrhalis in the immunocompromised or chronic pulmonary disease
- pseudomonas aeruginosa in patients with cystic fibrosis or bronchiectasis
- staphylococcus aureus in patients with cystic fibrosis
8
Q
Causes of atypical pneumonia
A
Mycoplasma pneumoniae
* can cause rash = erythema multiforme (pink ring, pale centre)
* can cause neurological symptoms
Chlamydophila pneumoniae = mild to moderate chronic pneumonia and wheeze
Coxiella burnetii = typically contracted from contact with infected birds
Legionella pneumophila
* caused by infected water supplies or air conditioning units
* Can cause SIADH = hyponatraemia
9
Q
Investigations for pneumonia
A
- Basic Obs
- CXR
- Bloods: FBC, U+E, LFT, CRP, blood culture
- Sputum culture
- O2 sats, ABG if <92% or severely unwell
10
Q
Abx for CAP
A
- Mild-moderate: amoxicillin PO. Clarithromycin or doxycycline if allergic.
- Severe: co-amoxiclav, cefuroxime, or cefotaxime IV (or levofloxacin if allergic), plus clarithromycin IV
- If hospitalised, start within 4 hrs. Monitor response to treatment with CRP
11
Q
Abx for HAP
A
- Piperacilin/tazobactam, 3rd generation cephalosporin, meropenem, or levofloxacin IV.
- Co-amoxiclav is a PO alternative or stepdown
- Add vancomycin or teicoplanin or linezolid if MRSA suspected
12
Q
Abx for aspiration pneumonia
A
clindamycin, levofloxacin, or piperacilin/tazobactam
13
Q
Duration of abx in pneumonia
A
- 5 days total usually sufficient
- longer if remains febrile or unstable, or for certain pathogens e.g. pseudomonas
- If starting IV, review after 48 hrs for possible PO stepdown
14
Q
Supportive care in pneumonia
A
- oxygen
- fluids
- paracetamol
15
Q
Prognosis of pneumonia
A
- fever should resolve within 1 week
- cough and SOB may take up to 6 weeks to resolve
- fatigue may persist up to 3 months
16
Q
Complications of pneumonia
A
- Respiratoy failure
- sepsis and septic shock
- uncomplicated parapneumonic pleural effusion, empyema, or lung abscess
- Death: 1% in community, 10% if admitted
17
Q
Pathophysiology of infective endocarditis
A
- infection of the endocardium, usually a (prosthetic or native) valve (mitral or aortic), usually following transient bacteraemia and turbulent flow past valve
- leads to formation of vegetation on valves containing bacteria, fibrin and platelets
18
Q
Causes of infective endocarditis
A
- bacterial: strep viridans, staph aureus
- fungal: candida, aspergillus
- non-infective: cancer, SLE
19
Q
Key features of infective endocarditis
A
Murmer (85%) + fever
20
Q
Septic signs and symptoms of infective endocarditis
A
- fevers, rigors and night sweats
- malaise
- weight loss
- splenomegaly
- clubbing
21
Q
Signs of subacute infective endocarditis
Usually due to immune-complex depositions and vasculitis
A
- Petechiae and splinter haemorrhages
- Janeway lesions: painless plantar/palmar lesions
- Osler’s nodes: painful infarcts in distal phalanges
- Roth spots: retinal haemorrhages with pale centre
- Glomerulonephritis
22
Q
Risk Factors for infective endocarditis
A
Increased turbulent flow
* valve disease
* prosthetic valves
* structural disease: unrepaired PDA, VSD
* rheumatic heart disease
Increased pathogen entry and bacteraemia
* IV drug use
* haemodialysis
* dermatitis
Chronic disease
* Diabetes
* Kidney disease
23
Q
Investigations in infective endocarditis
A
Blood cultures
* 3 sets from different sites before starting abx
* within 6 hours if subacute, within 1.5 hrs if acute
* 90% sensitive
Bloods
* FBC: normocytic anaemia
* ↑ neutrophils
* ↑ ESR/CRP
* Rheumatoid factor may be +ve (due to IE itself or RA)
Heart investigations
* Echo: transthoracic, then transoesophageal if -ve
* CXR: cardiomegaly
* ECG: ↑PR interval. Monitor to decide whether surgery required
Urinalysis: microhaematuria
24
Q
Duke Criteria in Infective Endocarditis
A
Diagnosis requires any 1 of:
* 2 major
* 1 major plus 3 minor
* 5 minor
Major Criteria
* +ve blood culture x2 or persistent
* +ve echo: vegetation, abscess, new regurgitation, or prosthetic valve dehiscence
Minor criteria
* RF +ve
* fever
* vascular immune-complex signs
* +ve blood culture (x1)
* +ve echo for other abnormality
25
Acute Management of Infective Endocarditis
**Abx as soon as blood cultures taken:**
* 4-6 weeks, including at least 2 weeks IV initially
* Empiric therapy and for streptococci: benzylpenicillin (or amoxicillin) + gentamicin
* staph. aureus: flucloxacillin if native valve, add rifampicin and gentamicin if prosthetic valve
**Surgery:**
* Debridement, repair or replacement required in 20%
* Indications: refractory HF, persistant sepsis or emboli, or fungal IE
26
Bacterial causes of meningitis
* <3 months old = Group B strep
* 3 months - 45 yrs = neisseria meningitidis
* > 45yrs = strep. pneumoniae
* other causes = staph. aureus, e. coli, h. influenzae
* Listeria monocytogenes: may occur in pregnancy, neonates, the alcohol misusers
27
Viral causes of meningitis
* enteroviruses; coxsackie, echovirus
* herpes simplex, HSV2 more than HSV1
* Mumps
* Measles
28
Fungal causes of meningitis
* Cryptococcus neoformans
* it has an insidious onset
29
Non-infectious causes of meningitis
* cancer: carcinomatous meningtitis
* drugs: co-amoxiclav, NSAIDs, IVIg, azathioprine
* Inflammatory and autoimmune sarcoidosis, SLE, Behcet's
30
Epidemiology of meningitis
* 40% of cases of bacterial meningitis are in children aged <15 years
* Commonest in first few months of life, affecting 1/2000 per year, then incidence drops to around 1/100,000 per year for the rest of life
31
Symptoms of meningitis
* Classic triad: fever, stiff neck, headache/altered mental status
* vomitting
* photophobia
* mottled skin
* confusion
* seizures
* rigors
* cold hands and feet
32
Signs of meningitis
* Kernig's sign: with hip and knee flexed, pain limits passive extension of the knee
* Brudzinskis sign: neck flexion leads to involuntary hip and knee flexion
* Both are around 10% sensitive and 90% specific for meningitis
* Cerebral oedema = loss of consciousness, papilloedema, and focal CNS signs
Meningococcaemia
* petechiae and purpura: look carefully all over including backs of legs etc
* septic shock: hypotension, ↓ capillary refill
* DIC
33
Risk Factors for meningitis
* immunosuppression, including complement deficiencies and asplenia
* Skull fracture or anatomical defects
* crowding: university halls, military barracks, Hajj
34
Investigations for meningitis
Bloods
* ↑WBC, ↑CRP
* U&Es and LFTs
* Blood culture +/- N. meningitidis PCR
* Coag: DIC
Lumbar puncture:
* CT and opthalmoscopy 1st if ↑ICP suspected
* Bacterial CSF: ↑polymorphs, ↑proteins, ↓glucose, bacteria on culture, gram stain. Listeria can be mixed polymorphs and lymphocytes
* TB CSF: ↑lymphocytes, ↑protein, ↓glucose, ZN stain +ve
* Viral CSF: ↑lymphocytes, viral PCR +ve
Other investigations
* Throat swab for N. meningitidis
* CXR: pneumococcal pneumonia, TB
35
Acute Management of meningitis
* resuscitate, including oxygen and fluids
* broad spectrum IV abx stat, e.g. cefotaxime. Add amoxicillin if age>50 or <3 months. Benzylpenicillin IM if pre-hospital
* dexamethasone IV if >3months old: ↓neurological complications, but doesn't affect mortality
36
Public health measures for meningitis
* notify public health about any case of meningitis or meningococcaemia
* isolate patient
* prophylactic abx: single dose of ciprofloxacin or 2 days of rifampicin. Give to all close contacts from the last 7 days, regardless of vaccination status
37
Complications of meningitis
* short term: ↑ICP, shock, DIC, subdural effusions, SIADH, seizures, venous sinus thrombus
* long term: cranial nerve palsies, deafness, limb amputation, memory or cognitive problems
38
Prognosis of meningitis
* 5% mortality rate in meningococcal
* 25% mortality rate in pneumococcal
* 35% mortality rate for listeria
39
What is encephalitis
Inflammation of the brain
40
Viral Causes of encephalitis
Most common
* Herpes simplex (HSV1>HSV2)
* VZV
* EBV
Others
* CMV
* HIV seroconversion
* measles
* mumps
* arboviruses (west Nile, Japanese, tick borne, St Louis)
* rabies
41
Other causes of encephalitis
* Autoimmune
* Idiopathic
* bacterial meningitis --> meningoencephalitis
* TB
* protozoa: malaria
* fungal: Aspergillus,Cryptococcus
42
Epidemiology of encephalitis
* annual incidence: 1/20,000
* Most common under 1 year old or over 65
43
Signs and Symptoms of Encephalitis
* Initially non-specific: fever, headache, nausea, vomiting, malaise
* Neuro symptoms: seizures, odd behaviour or confusion, ↓level of consciousness, focal signs
44
History for Encephalitis
include travel and bite exposure
45
Investigations for encephalitis
Bloods
* blood culture
* serum viral PCR
* If suspected: toxoplasma IgM, malaria film
Image with MRI or contrast-enhanced CT
* Temporal lobe inflammation: usually HSV or autoimmune
* meningeal irritation: meningoencephalitis
Special tests
* LP: ↑protein (most causes), ↑lymphocytes (viral, autoimmune), ↑PMNs (bacterial), ↓glucose (bacterial). Identify pathogen with viral PCR and gram stain
* EEG: optional
46
Management of Encephalitis
* Aciclovir IV stat to cover HSV. Continued for 14-21 days if HSV confirmed
* Consider ganciclovir for CMV if immunocompromised
* anticonvulsants for seizures
* autoimmune encephalitis: immunosuppressants (steroids, IVIg, plasma exchange) and treat for any underlying cancer
* If infectious notify public health authorities
47
Complications of encephalitis
* Short term: seizures, ↑ICP, SIADH, diabetes insipidus
* Long term: neurological complications, including motor and cognitive problems
48
Prognosis of encephalitis
* 10% mortality overall
* For HSV, treatment reduces mortality from >50% to 20%
49
Pathogens that cause gastroenteritis
* Viral: norovirus, rotavirus, astrovirus, adenovirus
* Bacteria: campylobacter jejuni, salmonella (usually S. enteriditis), shigella, E. coli, vibrio cholera, clostridium difficile
* protozoa: giardia, cryptosporodium, cyclospora, entamoeba
50
Transmission of gastroenteritis
* most are faecal-oral, and can be person to person, water-borne or foodborne
* some are zoonotic
* campylobacter, shigella and giardia can be sexually transmitted, especially in MSM
51
Signs and symptoms of gastroenteritis
* acute diarrhoea and/or vomitting
* anorexia
* malaise
* fever
* weight loss
52
Investigations in gastroenteritis
* most cases require minimal if any
* stool culture and microscopy if there is bloody stool, the patient is immunocompromised, there is recent travel to the developing world, or symptoms are prolonged (>7 days)
* Basic bloods if unwell: FBC (↑WBC), U&E (dehydration), CRP, LFT
53
Management of gastroenteritis
most cases do not require admission and can be managed at home with regular oral fluid intake
Inpatient management
* fluids (PO or IV)
* anti-emetics or anti-diarrhoeals if severe (do not give in dysentry)
* abx if systemically unwell or immunocompromised. Ciprofloxacin (campylobacter, salmonella, shigella) or tetracycline (V. cholera)
Infection control
* isolate patients with D+V
* any food poisoning or suspected food poisoning is a notifiable disease
54
Complications of gastroenteritis
* lactose intolerance
* Guillian-Barre syndrome
* Reactive arthritis
* Haemolytic uraemic syndrome after E. coli
55
Pathophysiology of C. diff infection
* gram +ve anaerobic bacillus
* transmitted by spores from people or the environment
* often follows abx course, especially clindamycin, cephalosporins or quinolones, which eliminate gut commensals (usually post 4-9 days, but can be up to 8 wks)
56
Presentation of C. diff infection
* Profuse watery diarrhoea. Bloody stool can occur but is rare
* abdominal pain and tenderness
* fever
57
Investigations in C. diff infection
* ↑WBC, sometimes very elevated. ≥15 = severe c. diff
* U&E. AKI = severe c. diff
* Stool PCR ± toxin immunoassay to confirm
58
Management in c. diff infection
* Stop any abx which may be causing it
* none-severe and sever: vancomycin PO = 1st line, fidaxomicin PO if vancomycin ineffective
* Life-threatening (shock, ileus, or megacolon): vancomycin PO/PR ± metronidazole IV. May need colectomy if there is toxic megacolon
* Consider faecal microbiota transplantation for recurrent disease
59
Complications of C. diff infection
* pseudomembranous colitis
* toxic megacolon
60
What is bacteriuria
bacteria in urine. may or may not be symptomatic
61
What is a UTI
significant bacteriruria (≥100,000 colony forming units/mL in MSU) + symptoms
62
What is a complicated UTI
UTI in the presence of certain risk factors, including renal or urinary tract abnormality, voiding difficulty, ↓ kidney function, indwelling catheter, immunosuppression, or virulent organism
63
Pathogens that cause UTIs
* E. coli (90%)
* Staph. saprophytics: occurs in sexually active women
* proteus mirabilis: suggests kidney stones
* enterococcus facealis: causes prostatis
* Klebsiella: usually in catheterised patients
* Staph. aureus: from haematogenous spread
* STIs: chlamydia, gonorrhoea
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Epidemiology
* annual incidence: 1/10 women, 1/100 men
* Lifetime risk: 1/2 women, 1/20 men
* Risk increases with age
* Although less common in men, they account for 40% of UTI hospitalisations
65
Symptoms of UTIs
* cystitis (lower UTI): frequency, urgency, dysuria, nocturia, haematuria, suprapubic ache
* acute pyelonephritis (upper UTI): fever ± rigors, loin pain, systemically unwell (e.g. vomiting)
66
Signs of UTIs
* fever
* suprapubic or loin tenderness
* cloudy or smelly urine
* swollen, boggy, tender prostate (prostatitis)
* Discharge (STI urethritis)
67
Risk Factors for UTIs
* demographic: female, age
* pregnancy
* pathogen exposure: sexually active, catheter
* stagnant flow: obstruction (prostate, stones), retention, extended holding
* infection prone states: diabetes, immunosuppression
68
Other differential diagnoses alongside UTI signs/symptoms
* overactive bladder
* STIs
* non-infectious inflammation: atrophic vaginitis, interstitial cystitis
* vaginitis
* stones
* bladder or renal cancer
69
Investigations for UTIs
Urine dipstick:
* nitrites or leukocytes esterase +ve
* if +ve: start treatment and send MSU for M,C&S
* If -ve: send MSU anyway if strong clinical suspicion, male, child, pregnant or immunosuppressed
MSU MC+S
* Microscopy shows leukocytes ± bacteria
* If <100,000 CFU/mL but pyuria (>20 WBC/mm3) = sterile pyuria (prev. treated UTI, prostatitis, STI, TB, appendicitis, bladder tumour, stones, PKD)
* if many different organisms, suspect contaminated (not mid-stream) and repeat MSU
Further investigations if indicated
* pyelonephritis: FBC, U+E, CRP, blood cultures
* Blood glucose to rule out diabetes
* Imaging: kidney US (obstruction/hydronephrosis), post-void bladder US, CT KUB (stones)
70
General Approach to manage UTIs
* Abx if symptomatic
* paracetamol +/or NSAIDs for symptom relief
* remove catheter if present
71
Treatment of lower single UTI in women
* nitrofurantoin (if eGFR≥45) or trimethoprim PO for 3 days
* pregnancy: treat even if asymptomatic. Nitrofurantoin 1st line (unless at term), amoxicillin or cefalexin 2nd line, all PO for 7 days
* any other complicated UTI: trimethoprim or nitrofurantoin PO for 7 days
72
Preventing recurrent UTI in women
* behavioural and lifestyle: increase daily water intake, pre/post coital washing, avoid spermicides and diaphragm
* consider vaginal oestrogen if post-menopausal
* prophylactic abx if very disruptive: nitrofurantoin if eGFR≥45 or trimethoprim PO taken post-coitus if sex-related, otherwise daily
73
Urology referral and imaging indications for UTI
* failure of other measures
* has risk factors for urinary tract abnormality: obstructive symptoms, history of stones, urinary tract surgery, gynae cancer
* immunosuppressed
* recurrent UTI with haematuria: urgent referral for suspected cancer
74
Treatment of lower UTI in men
* nitrofurantoin (if eGFR≥45) or trimethoprim PO 7 days for cystitis
* ciprofloxacin PO for 2-4 wks if there if prostatis, IV if severely unwell
75
Treatment for upper UTI
* most upper UTIs are uncomplicated and can be managed with PO abx (cefalexin or ciprofloxacin for 7-10 days)
* if there is no response within 24hrs, signs of sepsis or in complicated UTI = hospitalisation and consider IV abx, e.g. 2nd-3rd generation cephalosporin or ciprofloxacin
76
Complications of UTIs
* infectious spread: pyelonephritis, perinephric or intrarenal abscess, prostatis, sepsis
* Kidney: AKI, hydronephrosis
* recurrence: 1 in 3 women, usually reinfection (new pathogen)
77
Prognosis of UTIs
symptoms resolve in 3-4 days with an effective abx, vs 5-7 days without treatment (or with a resistant organism)
78
What is cellulitis
Inflammation of dermis and subcutaneous tissue. Most commonly group A strep, then staph aureus
79
Signs and symptoms of cellulitis
Skin:
* inflammation: painful, red, hot, swollen
* poorly demarcated
* precipitating lesion: trauma, ulcer, bite, skin damage from chronic condition
* may have associated skin abscess
non-dermal features:
* lymphadenopathy
* systemic symptoms: fever
80
Common sites for cellulitis
* lower legs (NOTE: bilteral lower leg cellulitis is rare, consider venous eczema)
* canula site
81
Risk factors for cellulitis
* previous cellulitis
* chronic disease: diabetes, chronic kidney disease or liver disease, cancer
* immunodeficiency
* venous insufficiency
* age
* skin disease, e.g. tinea pedis
82
Investigations for cellulitis
Affected area:
* look for portal of entry and ask about trauma
* draw around edge of area to monitor progress
* swab for culture only needed for severe/resistant infections, or unusual exposures (penetrating injury, water-born, acqiured abroad)
Bloods if systemic symptoms:
* ↑WBC and ↑CRP
* Blood cultures
Investigate associated conditions
* foot Xray for osteomyelitis
* D-dimer, ultrasound and Well's score if suspected DVT
83
Management of cellulitis
Abx
* flucloxacillin PO for 5-7 days 1st line for most
* if penicillin allergyc, doxycycline or clarithromycin PO
* if near eyes or nose, or for human/animal bite wounds, co-amoxiclav PO
* if severe, cefuroxime, ceftriaxone, flucloxacilling, co-amoxiclav, or clindamycin IV
* if MRSA, vancomycin, tecioplanin or linezolid IV
Analgesia
* simple analgesia PO
* leg elevation can ease pain
If at cannula site
* remove cannula, resite, and culture needle tip
84
Complications of cellulitis
* thrombophlebitis
* sepsis
* toxic shock syndrome
* lymphangitis and secondary lymphoedema
* cavernous sinus thrombosis if facial
85
pathophysiology of necrotizing fasciitis
* Bacteria enters through a break in the skin following surgery, trauma, IV injection, or insect bite
* Infection spreads rapidly across fascial layer, leading to tissue death of fascia and subcutaneous tissue
86
Types of necrotizing fasciitis and common causes
* Polymicrobial (type 1)
* Monomicrobial (type 2) = Group A strep, with tissue destruction driven by exotoxins A, B & C
87
Risk factors for necrotizing fasciitis
* IV drug use
* diabetes
* obesity
88
Signs and symptoms of necrotizing fasciitis
* Rapidly expanding, inflammed area of skin. May progress to bullae and dusky, purplish discolouration
* severe pain out of proportion to skin signs
* skin crepitus: crackly on palpation
* sepsis and systemic symptoms
89
Investigations in necrotizing fasciitis
* Bloods: ↑WBC, ↑CK, ↑lactate
* XR, CT, or MRI may help aid diagnosis, showing gas in soft tissue
90
Management of necrotising fasciitis
* urgent surgical debridement
* IV abx: carbapenem + clindamycin ± MRSA coverage (e.g. vancomycin)
91
What is septic arthritis
bacterial infection of a joint that can rapidly destroy it
92
common pathogens that cause septic arthritis
* staph. aureus
* N. gonorrhoea
* gram -ve bacilli
93
Signs and symptoms of septic arthritis
* acute monoarthritis: hot, red, swollen, painful joint. May be immobile
* Most commonly affects knee
* Fever, systemically unwell
94
Risk factors for septic arthritis
* RA
* diabetes
* immunosuppression
* kidney failure
* joint replacement
95
Investigations for septic arthritis
Bloods and microbiology
* FBC and CRP
* Joint aspiration: gram stain and culture
* blood culture
Imaging
* XR should be done but is often normal
* CT and MRI is more sensitive but only used if there is diagnostic uncertainty
96
Management of septic arthritis
* Abx for 4-6 weeks , initially IV for 2 weeks. Flucloxacillin for staph. aureus, vancomycin for MRSA, or cefataxime for N. gonorrhoea or gram -ve bacilli. Start after joint aspiration
* drainage of joint if severe. This may involve serial aspirations if the joint is easily accessible (knee, elbow), or open washout in theatre if less accessible (e.g. hip)
* splinting
97
Pathophysiology of osteomyelitis
* Infection can come from direct/contiguous spread (cellulitis, abscess, trauma, surgery prosthesis), or haematogenous spread, which is commoner in kids, patients with urinary catheters, or TB
* Once infected, leukocytes enter bone, releasing enzymes which cause bone lysis and leave necrotic areas known as sequestra. New bone often forms around this
* Chronic osteomyelitis if >6 months of infection
98
Pathogens that cause osteomyelitis
* Staph. aureus = most common
* Less common = strep. pyogenes (kids), H. influenzae (kids), gram -ve bacilll (elderly)i, pseudomonas aerguinosa (IV drug users)
99
General features of osteomyelitis
* Local inflammation
* pain
* slight effusion of neighbouring joints
* systemic symtoms
* can be asymptomatic in diabtes due to neuropathy
100
Signs and symptoms of vertebral osteomyelitis
* localised spine inflammation
* Chronic back pain, which may be worse at rest and at night
* there is often associated discitis
101
Risk factors for osteomyelitis
Portal for pathogen entry
* Trauma: open fracture or orthopaedic surgery
* surgical prostheses
* IVDU
Diseases
* TB
* diabetes
* peripheral vascular disease
* immunosuppression
* alcoholism
* sickle cell disease
102
Investigations for osteomyelitis
Blood and microbiology
* ↑WBC/ESR/CRP
* bone culture is gold standard
* also culture blood, pus, and local joint effusion
* look for cause e.g. urine
Imaging
* X-ray: dark area in bone, soft tissue swelling. Signs may be minimal in acute infection
* MRI provides clearer picture if diagnosis is uncertain
103
Management of osteomyelitis
* abx for 6 weeka, IV then PO, Flucloxacillin ± fusidic acid or rifampicin in first 2 weeks
* Debridement to drain pus and remove sequestra if severe
* chronic osteomyelitis may require 12 weeks of abx and extensive surgery
104
Complications of osteomyelitis
* septic arthritis
* fracture
* deformity
105
Epidemiology of malaria cases imported to the UK
* 1500 cases annually, many from those visiting family members in country of origin
Species
* Plasmodium falciparum: 80%, usually Africa
* Plasmodium vivax: 10%, usually South Asia
* Plasmodium ovale & Plasmodium malariae: 10%
106
General signs and symptoms of malaria
* Fever: all tertian (48-hourly) except quartan (72-hourly) in P. malariae. These classic patterns aren't always seen
* rigors
* headache
* diarrhoea and vomitting
* hepatosplenomegaly
107
Signs and symptoms of falciparum malariae
* Flu-like prodrome: myalgia, malaise, headache, anorexia
* irregular fever initially
* Jaundice
108
Signs and symptoms of complicated falciparum malaria
* Mortality approaches 100% if sever and untreated
* cerebral malaria: altered mental status, seizures, coma, decerebrate posturing, ↑plantars, teeth-grinding
* AKI
* Bleeding: haemoglobinuria (blackwater fever), DIC, retinal haemorrhages
* Metabolic: hypoglycaemia, metabolic acidosis
* ARDS and pulmonary oedema
* splenic rupture
* shock
109
Investigations to diagnose malaria
Blood films
* serial testing: up to 3 times if 1st -ve
* Thick film - quick yes or no malaria - and thin film - which subtype
* Also shows parasitaemia (%RBCs afected) and stage, with imminent decline in patient condition due if there are ↑shizofonts. Dangerous if parasitaemia >2%, life threatening if >5%
* Simple but less sensitive antigen detection kits are available too
110
Investigations to do in malaria patients
Bloods:
* FBC: anaemia, low platelets (due to increased spenic activity during haemolysis = increased clearance)
* Coag: DIC
* Hypoglycaemia
* ABG: metabolic acidosis
* U+E: AKI
Other tests:
* urinalysis: blood
* blood cultures to rule out bacterial sepsis
111
Prophylaxis for malaria
* Start 1 week before to check for side effects, and continue until 4 weeks after
Areas without chloroquinine resistance
* chloroquinine (daily) + proguanil (weekly)
Areas with chloroquinine resistance (any 1 of)
* atovaquone/proguanil. Few side effects and is taken from 1 day before
* doxycycline
* mefloquine (Larium): once weekly
Also
* long sleeves dusk till dawn
* mosquito nets
* DEET repellent
112
Treatment for malaria
* P. vivax, P.ovale & P. malariae: chloroquinine + primaquine
* Uncomplicated P. falciparum: 1st line artemether/lumefantrine (Riamet). 2nd line: quinine/doxycycline, or atovaquone/proguanil
* Complicated P. falciparum (cerebral, renal, or shock): artesunate IV (preferably), or quinine IV + doxycycline IV/PO. Careful monitoring of fluid, lactate, U+E. Transfuse if anaemic
113
Complications of malaria
* P. vivax & P. ovale can remain dormant in the liver as hypnozoites and relapse years later. Cause tropical splenomegaly syndrome if recurrent
* P. malariae can lielow in blood for years, with or without symptoms
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Side effects of chloroquine
* Headache
* psychosis
* retinopathy
* Contraindication: epilepsy
115
Side effects of primaquine
* epigastric pain
* triggers haemolysis in G6PD deficiency (check 1st and give atovaquone/proguanil if +ve)
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Side effects of atovaquone/proguanil
* abdo pain
* nausea
* dizziness
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Side effects of mefoquine
* nauea
* dizziness
* insomnia
* vivid dreams
* psychosis
* Contraindication: epislepsy, psychosis
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Side effects of doxycycline
* photosensitivity
* diarrhoea
* oesophagitis
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What pathogen causes TB
Infection by one of the Mycobacterium tuberculosis complex: M. tuberculosis, M. bovis, or M. africanum
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How is TB spread
Respiratory transmission
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Histological finding in TB
Caseating granuloma that can spread to local lymph nodes
122
Systemic features of TB
* fatigue
* malaise
* fever
* night sweats
* weight loss
* anorexia
* immunosuppression
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Signs and symptoms of pulmonary TB
* Chronic productive cough ± haemoptysis, clubbing
* can progress to pneumonia, pleural effusion, lobar collapse, and bronchiectasis
* accounts for 60% of TB causes in UK
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Signs and symptoms of genitourinary TB
* frequency, dysuria, loin/back pain, haematuria
* can progress to renal TB, salpingitis, epididymitis, and cystitis
* 2nd most common TB presentation in UK
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Other types of TB (apart from pulmonary and genitourinary)
* Skeletal TB: most commonly affects spine (Pott's disease). Can lead to vertebral collapse
* Skin TB (aka lupus vulgaris): rough nodules, often on the face or shin which are +ve for AFB, scrofula (cold cervical lymphadenopathy), erythema nodosum, erythema multiforme
* Peritoneal TB: abdomincal pain, diarrhoea, vomiting, ascites
* TB meningitis: neurological signs are usually preceded by weeks of systemic symptoms
* TB pericarditis: acute or constrictive pericarditis
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Signs and symptoms for miliary TB
* affects multiple organs so symptoms are varied
* there are often retinal signs
127
Risk factors for TB
* contact with infected individuals
* South Asian or African
* Homeless
* Immunosuppressed, including HIV and extremes of age
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What is the first line investigation in TB
CXR, get it even in extrapulmonary TB
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CXR findings in primary TB infection
* Distinct Ghon fous in the middle zone, or an area of patchy consolidation. Sometimes the parenchymal focus is too small to detect
* Extra-parenchymal findings: ipsilateral hilar lymphadenopathy (especially in kids), effusion (especially in adults)
* these signs may resolve following successful immune response, leaving just calcified nodies in 1/3
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CXR findings in secondary TB infection
* cavitating lesion (air-filled) in the apices, especially in the right
* other signs including patchy consolidation and linear or nodular opacities
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CXR findings in miliary TB
* Diffuse 1-10mm shadows throughout lung fields
* The term miliary is used to describe a CXR where there are more nodules than can be easily counted
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Microbiological Investigation in TB
Getting samples:
* pulmonary: 3 sputum samples (including 1 early morning), idaelly spontaneous. Otherwise induce with nebulised saline or do bronchoalveolar lavage.
* extra-pulmonary: aspirate or biopsy lymph nodes, ascites, organs, pus, urine, or CSF
Investigations
* MC+S: AFB smear and microscopy usually involves Ziehl-Neelson staining which is around 65% sensitive. Culture in a Lowenstein-Jenson medium typcially takes 4-8 weeks and is around 80% sensitive
* NAAT allow diagnosis a week earlier than culture, with a similar sensitivity
* PCR for rifampicin resistance
* Histology of biopsies for caseating granuloma
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Immunological testing in TB
Methods
* Mantoux (aka PPD): a tuberculin skin test. A delayed hypersensitivity response to tuberculin develops from 2-10 weeks after primary infection. Also +ve post BCG vaccination
* Interferon gamma release assays (IGRA): measures T cell response to TB antigens.
Uses and limitations
* Bother are around 80% sensitive
* cannot distinguish between latent and active TB
* more useful for screening contacts than diagnosis. Mantoux usually first, then confirmed with IGRA, or use IGRA first in those with previous BCG
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Other investigations for TB (apart from CXR, Microbiological & Immunological testing)
* HIV screening
* Basic bloods - FBC, LFT, U+E - may show systemic and extrapulmonary disease, and are required for baseline values before starting treatment
* imaging for suspected extrapulmonary TB: CT/MRI (CNS, abdo, bone), US (pericardial, lymph nodes, GU), XR (bone)
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Infection control in active TB
* Notify public health authorities
* screen close contacts
* for pulmonary TB, isolate patient in a single room, ideally negative pressure, for first 2 weeks of treatemnt. Have them wear msak if they leave the room.
* Masks and gowns for healthcare workers are only needed for aerosol-generating procedures like sputum induction of bronchoscopy, or for multiple drug resistant TB
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Drug treatment in active TB
* Treat before confirmation by culture if clinical suspicion is high. Consider continuing treatment even if culture is negative but clincal signs are strong
* 6 months treatment with RIPE (rifampicin, isoniazid, pyranizamide & ethambutol) = 4 for 2 months, 2 for 4 months
* Add further 6 months of dual therapy for meningeal TB
* Add steroids for meningeal and pericardial disease
* consider directly observed therapy (DOT) to increase adherance
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management in latent TB
Offer treatment to those with latent TB plus any 1 of:
* close contacts with active TB
* At high risk of progression to active TB: immunosuppressed, aged <5yrs, alcoholic, IVDU, diabetes or CKD
* immigrants from high incidence countries
* healthcare workers
Drug options
* 3 months isoniazid + rifampicin
* 6 months isoniazid monotherapy if need to avoid rifampicin e.g. on antiretrovirals
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Prevention of TB
Mantoux/IGRA screening for:
* Healthcare workers who are unvaccinated or from high incidence countries
* close contacts (household partner) of people with active TB
* Immigrants from high incidence countries
Actions
* If -ve, give BCG
* If +ve, asses for active TB and treat latent/active TB as needed
* in older immigrants, benefits of BCG (if age >35) and latent TB treatment (if age >65) may be smaller so are not routinely indicated
BCG vaccine
* redues infection risk by 25% and active TB risk by 70% (in children)
* in addition to those identified through screening, give to children at risk
* also offer to those at high risk through occupational exposure
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Side effects of rifampicin
* hepatitis (so stop if increase bilirubin)
* orange urine/tears
* P450 inducer (inactivates warfarin and contraceptive pill)
* flu-like symptoms
140
Side effects of isoniazid
* hepatitis
* agranulocytosis
* P450 inhibitor
* peripheral neuropathy can result from pyridoxine depletion, so give supplements to all
141
Side effects of pyrazinamide
* hepatitis
* arthralgia
142
Side effects of ethambutol
* optic neuritis
* colour vision goes first, so check it using Ishihara charts before starting
143
What type of virus is HIV
A single stranded, RNA retrovirus
144
How is HIV transmitted
* sex (including oral)
* IV drug use
* blood transfusions
* vertically
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How does HIV enter cells
* attaches to CD4 T cells and macrophages
* Then integrates into DNA
* moves to lymph nodes
146
Time of course of HIV infection
* 1-6 weeks post-infection, seroconversion illness occurs, similar to infectious mononucleosis
* Then latent as the immune system mounts partial response but CD4 count drops progressively. During this time 30% develop persistent (> 3mnths) generalised lymphadenopathy
* after around 10 years, infections and cancers begin to develop
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Stages of HIV
Normal CD4 count is about 800 cells/mm3
* Stage 1 ≥ 500
* Stage 2 < 500
* Stage 3 < 200
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Signs and symptoms of seroconversion illness
* lymphadenopathy
* pharyngitis
* systemic: fever, malaise
* pain: myalgia, headache
* maculopapular rash
* lasts 1-2 weeks
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Respiratory presentation of HIV
* Pneumocystis jiroveci. Fungal infection that causes dry cough, sweats, SOB and desaturation on exertion, but no chest signs
* Other fungal infections: aspergillus, cryptococcus, histoplasma
* TB: pulmonary TB or atypical and disseminated forms such as miliary TB and TB meningitis
* Strep and staph pneumonia
* CMV
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Neurological presentation of HIV
* Toxoplasma encephalitis: protozoal infection. Focal neurological signs
* Cryptococcal meningitis: fungal infection. Causes insidous, chronic meningitis, usually without stiff neck
* Primary cerebral lymphoma
* progressive multifocal leukoencephalopathy: JC virus infection
* HIV dementia: neurological decline in multiple domains, in the absence of other infection
* HIV peripheral neuropathy
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Skin presentation of HIV
* Kaposi's sarcoma: due to human herpes virus 8. Purple papules on the face, mouth, back, lower limbs, or genitalia. Can also affect GI and respiratory tract
* Multi-dermatomal zoster (shingles)
* Recalcitrant psoriasis
152
HIV presentation in the mouth
* oral and oesophageal candidiasis
* oral hair luekoplakia: non-malignany white growths on the lateral tongue due to EBV
* HSV and aphthous mouth ulcers
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GI presentation of HIV
* Cryptosporidiosis: protozoa. Chronic diarrhoea
* CMV colitis
* HIV wasting syndrome: unexplained weight loss >10%
* Mycobacterium avium complex (MAC): GI, lung or disseminated
* Fungal: cryptococcus, histoplasma
* Other bacteria: salmonella, shigella
* Hepatitis B and C
154
Cancers in relation to HIV
B-cell lymphoma: EBV related
Cervical and anal cancers: HPV related
Lung cancer
Head and neck cancers
155
HIV presentation in the eye
CMV retinitis. Mozarella pizza sign on fundoscopy
156
Infections by CD4 level in HIV
* 200 - 500:
* 100 - 200:
* 50 - 100:
* <50:
* 200 - 500: TB, candida, VZV, Kaposi's, other pneumonias
* 100 - 200: PCP, histoplasmosis, PML
* 50 - 100: atypical TB, CMV, retinitis/colitis, toxoplasmosis, cryptosporidiosis, cryptococcal meningitis
* <50: MAC
157
Investigations to make a HIV diagnosis
* Serum HIV combined antibody + p24 antigen test screen, then confirm with Western Blot. 50% detectable within 1 month of infection, and nearly all by 6 months
* If +ve, screen for: TB, hepatitis A-C, syphilis, Toxoplasma, CMV
* Genotype testing to guide drug treatment
* Pregnancy test for women
* Baseline bloods: FBC, U&E, LFT, lipids, glucose
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Tests for specific presentations in HIV
* PCP:
* Toxoplasma:
* Cryptococcal meningitis:
* PCP: CXR shows bilateral interstitial infiltrates
* Toxoplasma: contrast-enhancing lesions on CT/MRI brain
* Cryptococcal meningitis: cryptococcal antigen in CSF and serum
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Monitoring in HIV
* 3 to 6 months: CD4 count, HIV quantitative RNA PCR (viral load), FBC
* Annual: U&E and LFTs, lipids, glucose
160
Lifestyle and preventative management of HIV
* counseling to prevent high-risk sexual behaviour. Lifelong condom use traditionally recommended, but good evidence that those with undetectable viral load cannot transmit even during condomless sex.
* Assistance with partner notification and contact tracing
* Vaccines: heptatitis A and B, annual flu, pneumococcal vaccine, HPV. Avoid live ones if CD4<200
161
Combination antiretroviral therapy for HIV
* Triple therapy: {2 x NRTI} + {NNRTI or protease inhibitor or integrase inhibitor}
* Research suggests clear benefits of starting treatment as soon as diagnosis is made
162
Common side effects of antiretroviral therapy
GI
* Diarrhoea and vomiting
* Hepatitis, especially nevirapine
Skin
* Mild rash
* In rare cases, hypersensitivity or SJS/TEN
Metabolic
* Lipodystrophy: fat reduction peripherally (head and limbs) but gain centrally. Seen with protease inhibitors, but possible with all
163
Common drug interactions with ART
* AEDs: phenytoin and carbamezapine should be avoided
* Sildenafil: use lower dose
* Lorazepam should be avoided
164
Definition of Pyrexia of Unknown Origin (PUO)
* Temperature >38 degrees for > 3 weeks, which is still undiagnosed after 1 week of hospital investigation
* Sub-types of fever of unknown origing: neutropenic, HIV, nosocomial
165
Causes of PUO
* Infection: abscess (chest/abdo/pelvic), infective endocarditis, TB, osteomyelitis, UTI, biliary infection, non-bacterial
* Connective tissue disease: polymyalgia rheumatica, temporal arteritis, adult-onset Still's disease, SLE, RA, PAN
* Cancer: lymphoma, leukaemia, renal cell cancer
* Others: drugs, IBD, PE, sarcoidosis, amyloidosis, thyrotoxicosis, Addison's
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Important infections to rule out for fever in a returning traveller
* malaria
* typhoid and paratyphoid fever
* influenza, HIV, viral hepatitis
167
Fever in a returning traveller: DDx if short incubation (<10 days)
* influenza
* Arboral: yellow fever, dengue
* Rickettsial infection
* relapsing fever
* leptospirosis
168
Fever in a returning traveller: DDx if intermediate incubation (10-21 days)
* malaria
* enteric fever: typhoid and paratyphoid
* viral haemorrhagic fever
* leptospirosis
169
Fever in a returning traveller: DDx if long incubation (>3 weeks)
* malaria
* acute shistosomiasis
* Viral: hepatitis A-E, HIV seroconversion
* Protozoal: african trypansomiasis, amoebic liver abscess
* TB
* rabies
170
Fever in a returning traveller: DDx if Carribean and Latin America
* arboviruses: dengue, Zika, yellow fever
* malaria in certain areas
* bacterial: bartonellosis
* Fungal: histoplasmosis
171
Fever in a returning traveller: DDx if South Asia
* arboviruses: dengue
* bacterial: enteric fever
* malaria
172
Fever in a returning traveller: DDx if Sub-saharan Africa
* Malaria
* bacterial: Ricketsial infection, enteric fever
* arboviruses: dengue, yellow fever
* helminths: acute shistosomiasis
* viral haemorrhagic fever: Ebola, Marburg, Lassa
173
What are the 5 moments of hand hygiene
BARFS
* **B**efore patient contact
* Before **A**sceptic technique
* **R**ight after patient contact
* After body **F**luid contact
* After patient **S**urroundings contact
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What are some notifiable diseases
* CNS: meningitis, encephalitis
* Respiratory: TB, Legionnaires, whooping cough, anthrax, SARS
* GI: food poisoning, haemolytic uraemic syndrome, infectious bloody diarrhoea, cholera, diptheria, enteric fever (typhoid, paratyphoid)
* Skin: leprosy, plague, small pox
* Neurological: rabies, botulism, tetanus
* malaria
* measles, mumps, rubella
* Infectious group A strep infections
* yellow fever
* viral haemorrhagic fever
175
Examples of gram +ve cocci
* staphylococcus
* streptococcus
* enterococcus
176
Examples of gram +ve bacilli
* clostridium (anaerobe)
* listeria monocytogenes
177
Examples of gram -ve cocci
* neisseria
* moraxella
178
examples of gram -ve bacilli
* E. coli
* Shigella
* Salmonella
* Campylobacter jejuni
* helicobacter pylori
* haemophilus influenzae
179
Mechanism of Action of penicillins
* inhibits synthesis of peptidoglycan layer of bacterial cell wall
* Some bacteria produce beta-lactamase and require the use of beta-lactamase resitant (BLR) penicillins
180
Side effects of penicillins
* Rash
* diarrhoea (esp. co-amoxiclav)
* hypersensitivity: anaphylaxis, serum sickness
* encephalopathy
* renal: AIN, crystalluria (amoxicillin)
* liver: cholestasis (flucloxacillin)
181
Contraindications of penicillins
* hypersensitivity
* reduce dose in renal impairment
182
Examples of penicillins
* amoxicillin
* co-amoxiclav
* flucloxacillin
183
Mechanism of Action of cephalosporins
beta lactam = inhibits synthesis of peptidoglycan layer of bacterial cell wall
184
Contraindications of cephalosporins
* hypersensitivity
* potentiates warfarin
* don't cover anaerobes
* autoimmune haemolytic anaemia
185
Examples of cephalosporins
* cefalexin
* cefuroxime
* ceftriaxone
* cefepime
186
Mechanism of action of carbapenems
beta lactam = inhibits synthesis of peptidoglycan layer of bacterial cell wall - with beta-lactamase resistance
187
Side effects of carbapenems
* neuro: headache, dizziness, seizure
* GI: diarrhoea and vomiting
* haematological: anaemia, eoisinophilia, decreased WBCs
188
Contraindications of carbapenems
* pregnancy
* breast feeding
189
Examples of carbapenems
* imipenem
* meropenem
190
Mechanism of action of aminoglycosides
inhibits protein synthesis at the bacterial 30S ribosome site
191
Contraindications and interactions of aminoglycosides
* pregnancy
* furosemide
* myasthenia gravis: exacerbates weakness
192
side effects of aminoglycosides
* ototoxicity
* nephrotoxicity
193
examples of aminoglycosides
* gentamicin
* streptomycin
194
Mechanism of action of tetracyclines
inhibits protein synthesis at the bacterial 30S ribosome site
195
Side effects of tetracyclines
* photosensitivity
* diarrhoes and vomiting
196
Contrainidications of tetracyclines
* pregnancy
* breast feeding
* children <12 yrs
* kidney failure
197
Examples of tetracyclines
* doxycycline
* tetracycline
* tigecycline
198
Mechanism of action of macrolides
inhibits protein synthesis at the bacterial 50S ribosome
199
Side effects of macrolides
* GI: nausea, vomiting, and diarrhoea
* hepatotoxicity
* rash
200
contraindications for macrolides
potentiates
* warfarin
* statins
* theophylline
* ergotamine
* carbamezapine
201
Examples of macrolides
* azithromycin
* erythromycin
* clarithromycin
202
Mechanism of action of quinolones
inhibits bacterial DNA synthesis via topoisomerase II or DNA gyrase inhibition
203
contraindications of quinolones
pregnancy
204
Side effects of quinolones
* GI: diarrhoea and vomiting, C. diff
* Neuro: headache, dizziness, seizure risk in those with epilepsy, peripheral neuropathy
* MSK: tendon rupture, arthralgia
* CV: increased QT, aortic dissection and rupture
* rash
* raised LFTs
205
Examples of quinolones
* ciprofloxacin
* levofloxacin
* moxifloxacin
206
Mechanism of action of glycopeptides
inhibits synthesis of peptidoglycan layer of bacterial cell wall
207
examples of glycopeptides
* vancomycin
* teicoplanin
