infection Flashcards
Define malaria
infection with protozoan Plasmodium usually transmitted with female Anopheles mosquito bite.
Life cycle of malarial parasite
- mosquito injects plasmodium (sporozoites) into bloodstream
- Invasion and replication of parasites in hepatocytes
- released into bloodstream and enter + infect RBCs to replicate (SYMPTOMS)
- => form Gametocytes taken up when another mosquito feeds and develops into sporozoites in mosquito gut
- then moves to salivary gland to be passed on to human the next bite
Which populations have innate immunity to malaria
- sickle cell anaemia
- GP6D deficiency
- pyruvate kinase deficiency
- thalassemia
presenting symptoms of malaria
symptoms are cyclical
- high fever (39+)
- headache
- flu-like symptoms (lethargy, fatigue)
- severe sweating
- shivering cold
*travel history (incubation period 1yr)
features of severe malaria (e.g. cerebral malaria)
- impaired consciousness
- seizures
- altered respiration
examination findings of malaria
- check for signs of severe malaria (impaired consiousness, seizures, altered respiration)
- basic obs (pyrexia)
- jaundice
- hepatosplenomegaly
- pallor (anaemia)
investigations + findings for suspected malaria
- THIN/THICK blood film
- bloods (FBC, LFT, U&Es, ABG)
- urinalysis (check for blood/ protein)
What groups are at risk of developing severe malaria?
- children
- pregnant women
- elderly (>65)
- immunocompromised (HIV)
Management for malaria
- anti-malarial drugs (depending on plasmodium type)
- monitor other contacts for malaria (NOTIFIABLE DISEASE => to public health authorities)
Define sepsis
Life threatening organ dysfunction caused by dysregulated host response to infection
Causes of sepsis
Infection => stimulates immune response =>
Vasodilation + increased capillary refill => raised bp (usually respiratory/ UTI => CXR)
Risk factors for sepsis
Immunocompromised
Diabetics
Elderly
Catheter
Open wound
IV drug user
How to assess for SEPSIS? + symptoms
- less time to do history/ examination => treat immediately
- A=> E approach for initial assessment of SEPSIS
- Airway
- Breathing- cyanosed, high RR, low O2
- Circulation- febrile, warm/ cold peripheries, long capillary refill time
- Disability- confused
- Everything (fever, rashes, blood glucose, fever)
Other Symptoms:
- high resp rate (tachypnoea)
- low bp
- fever
- tachycardia (high HR)
- malaise/lethargy
- nausea/vomiting/ diarrhoea
- low urine output = marker of AKI
How to diagnose sepsis? (Criteria)
QSOFA score - 2/3= SEPSIS
- Altered mental status (GCS<15)
- increased resp rate (>22)
- Low systolic bp (<100)
NEWS2 =/>5 = SEPSIS
Investigations for sepsis
Bedside
- hourly urine output
- blood glucose
- ECG - rule out MI
- Urinalysis - check for UTI
Bloods:
- blood cultures
- Venous blood gas => serum Lactate (marker of severity/ tissue hypoperfusion)
- FBC- check for thrombocytopenia (worse prognosis)
- U&E- check for renal dysfunction
- LFT- high bilirubin (organ dysfunction)
- high CRP (not specific)
- Clotting screen- elevated PT/APTT
Imaging:
- CXR - check for Respiratory tract infection
Treatment for SEPSIS (SEPSIS 6- give OAF, take LOB/ BUFALO)
- inform senior
1. Give 3 - oxygen- >94% (vasodilation in lungs)
-broadspectrum IV antibiotics- within hour - IV fluids- increase preload/stroke volume => increase O2/blood delivery to tissues
*over oxygenation => hyp
- Take 3
- blood cultures (give antibiotics before)
- lactate (see if they need ITU)
- urine output (measure fluid balance so not giving too much fluid)
Define HIV
infection of the human immunodeficiency virus
Transmission of HIV
- sexual contact (heterosexual mainly)
- blood contact (mother=>baby during intrauterine, breastfeeding), needle sharers, blood transfusions, organ transplantation.
pathophysiology of HIV
- HIV binds to CD4+ T cells via gp120 receptors
- reverse transcriptase codes the viral genome => incoporates into hosts DNA
- HIV multiples => T cell death => depletion
Presenting symptoms + signs of HIV
- Seroconversion (self-limiting)
- fever
- night sweats/ chills
- sore throat , encephalitis, diarhhoea
- SIGNS: lymphadenopathy, oral ulcers, rashes, - early/ asymptomatic
- quite well
- can get lymphadenopathy/ oral thrush/ weight loss - AIDS- syndrome of secondary diseases due to immunodeficiency
Direct complications of HIV
- Neurological- polyneuropathy, dementia
- Lung- interstitial pneumonitis
- Heart- cardiomyopathy
- Haematology- anaemia
- GI- anorexia
- Eyes- cotton wool spots
Secondary complications of HIV (from immunodeficiency)
- bacterial infection (TB, pneumococcal, skin)
- viral infection (HPV, VSZ)
- fungal infection (canadiadis, cryptococcus)
- protozoan (toxoplasmosis)
- tumours (kaposi sarcoma, SCC)
Investigations + findings for HIV
- HIV test (HIV antibodies, PCR test for viral RNA, viral load, CD4 count)
- CXR- Pneumocystic pneumonia
- brain CT or MRI, LP - Cryptococcal meningitis
- colonoscopy and biopsy - CMV (colitis)
- brain CT or MRI- Toxoplasmosis
- stool microscopy- Cryptosporidia
Management of HIV
Combo of Anti-retroviral therapies (ARTs)
- nucleoside reverse transcriptase inhibitor (NRTIs)
+ 1 of
- integrase inhibitor (INI)
- non-nucleoside reverse transcriptase inhibitor (NNRTI)
- boosted protease inhibitor (PI)
What should be given for potential/future exposure to HIV
pre-exposure prophylaxis (prEP) ARTs
Define infectious mononucelosis (glandular fever) and it’s main cause
- infection mainly caused by Epstein-Barr virus
- aka kissing disease
- usually transmitted via saliva (kissing)/ sex
- mild in children, severe in adults
Presenting symptoms of infectious mononucleosis
- fever
- sore throat (pharyngitis)
- regional lymphadenopathy (tender, non-erythematous)
- malaise (unwell)
Examination findings of infectious mononucleosis
- pyrexia
- regional lymphadenopathy
- splenomegaly
- signs of hepatitis (jaundice, hepatomegaly)- adults more likely to have
Investigations for infectious mononucleosis
Bedside: Throat swab
- positive heterophile antibodies (Paul Bunnel test)- IgM AB agglutinate red cells of other animals(non-specfic)
- EBV antibodies (specific + sensitive)
Bloods:
- FBC- raised WCC, Hb-anaemia
- LFTs- raised AST,ALT (hepatitis)
Imaging
- Abdomen Ultrasonography - detect splenomegaly
- CT abdo - detect splenic rupture
Management of infectious mononucleosis
- hydration
- analgesia (paracetomol/ ibuprofen -NSAID)
- antipyretics
- Lifestyle - stop alcohol, avoid physical contact with others (kissing, sports => splenic rupture)
For severe disease:
Upper airway obstruction => corticosteroid (prednisilone)
Thrombocytopoenia => corticosteroid/ IV imunoglobulin
Why avoid giving antiboitics in infectious mononucelosis
- can cause antibiotoic induced rash
Complications of infectious mononucleosis
- splenic rupture
- Viral meningitis
- thrombocytopenia - corticosteroids
- depression
- Guillan- Barre syndrome
- Burkitt’s lymphoma (cancer)
define herpes simplex virus
sexually transmitted disease spread by direct contact
- HSV1(most common)
- HSV2
Types of herpes
- oral- ulcers on nose/lips (herpes labialis) or pharyngeal/oral mucosa (gingivostomatitis)
- genital- ulcers on external genetalia
- ocular- inflammation of eye usually blepharoconjuctivitis
- herpetic whitlow- infection o finger
symptoms of genital herpes
- usually asymptomatic
- fever, malaise
- multiple painful blisters around genetalia
- usually burst and leave ulcers
- urethral,vaginal discharge
symptoms of oral herpes
- fever, sore throat, lymphadenopathy
- painful, burning, itching
- blisters around the nose/mouth (herpes labialis)
- blisters in pharyngeal/oral mucosa (gingivostomatitis)
symptoms of ocular herpes
- mainly asymptomatic
- red, watery eye
- blurred/reduced vision
- hazy cornea
- irregular pupils (uveitis)
management of herpes
genital
- anaesthetic
- fluids to dilue urine
- oral acyclovir
ocular
- refer to opthamologist => topical anti-virals
oral
- analgesia
- oral acyclovir
- avoid triggers (stress, sunlight)- suncream lip balm
complications of herpes
- worse in immunocompromised individuals
- eczema herpetica
- erythema multiforme (target shaped lesions)
- herpetic whitlow
- eye disease
- meningitis/ encephalitis
define varicella zoster
- chicken pox is caused by infection of varicella zoster virus
- spread by direct contact/droplet infection
- incubation period of <3 weeks
symptoms of varicella zoster virus
- fever, malaise, fatigue
- nausea, myalgia, headache, decreased appetitie
- followed by small, red itchy widespread rash which start on chest/face/back
- forms itchy blisters <5 days
management of varicella zoster virus
- paracetamol
- topical calamine lotion (for itch)
- chlorophenamine (anti-histamine - for itch)
- fluids, soft clothes, short nails to avoid scratching
if severe complications/ pregnant/immunocompromised
- oral acyclovir
complications of varicella zoster virus
Children:
- bacterial skin infection (impetigo, cellulitis, erysipeles, necrotising fasciitis)
- neurological (Reye’s, cerebellar ataxia, encephalitis, myelitis)
Adults (more severe complications/ hospitalised)
- hepatitis
- encephalitis
- pneumonia
Long term: VZV stays dormant in spinal ganglia => activated in adults as herpes zoster virus (shingles)
differentials for chicken pox
Widespread Rashes
- herpes zoster (painful unilateral blotchy rash)
- herpes simplex
- coxsacchie virus (hand,foot,mouth disease)
- drug induced
- contact dermatitis
- measles (fever/watery eyes=> red blotchy rash first on forehead)
Other infection
- impetigo (yellow crusting in face, contagious)
- scabies- bite (itchy, red rash)
- syphillis -STI (cold sores => hair loss, sore throat, rash)
- TSS
Skin diseases
- guttate psoriasis (small, round scaly spots)
- erythema multiforme- allergy (symmetrical red raised lesions)
- dermatitis herpetiformis- coeliac disease (intense,itchy,blistering rash)
- steven johnson (rare)- allergy (fever => blistering rash => skin peels and heals)
- henoch-schonlein purpura - IgA vasculitis
