1. Breach of integrity of host barrier 2. Bacterial toxin release 3. Mediator release 4. Effects of excessive mediators - Exotoxin: Th1 -> pro-inflammatory -> septic shock + MODS - Endotoxin: Th2 -> anti-inflammatory -> immunoparalysis

- Weight loss - Lymphadenopathy - Opportunistic infection: thrush, skin, oral - (Primary infection) Flu-like

- Serum (acute/recovery phase) - antigen/antibody presence - CD4 lymphocyte count ( symptomatic) - PCR assay (viral load)

Lifelong antiretroviral therapy - Reverse transcriptase inhibitors - Integrase inhibitor - Protease inhibitor Prevention: - Education and behaviour - Pre- and post-exposure prophylaxis

Infection Flashcards by Emma Brandie

Infective gastroenteritis

Inflammation of stomach and intestines due to infection

- 3+ stools in 24 hours +1 (fever, vomiting, abdominal pain, blood/mucus)

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Non-inflammatory gastroenteritis

Secretory enterotoxin mediated. Watery diarrhoea.

Enterotoxigenic E. Coli (travellers)
Bacillus
Staph aureus
Rotavirus
Norovirus
Giardia
Cryptosporidium
Vibrio cholera

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Inflammatory gastroenteritis

Toxin damage and mucosal destruction. Bloody diarrhoea + pain/fever etc

E. Coli (SLT)
Campylobacter
Shigella
Salmonella
Staph aureus
Entamoeba histolytica
Adenovirus
C. Diff - prevent (4C’s)

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Infective gastroenteritis investigations

Assess hydration
Inflammatory features (bloods)
Routine stool culture (campylobacter, E. Coli O157, Salmonella, Shigella)
Specific stool culture
PCR (viral)
Stool microscopy (parasite)
Blood culture
Renal function
Imaging

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Infective gastroenteritis management

Hygiene (prevention)
Rehydration
Fasting
Antimicrobials
Tx of complications
Metronidazole for parasitic

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Haemolytic-uraemic syndrome (HUS)

Acute renal failure
Haemolytic anaemia
Thrombocytopenia
Bloody diarrhoea, fever, vomiting, weakness following E. Coli O157 infection

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Post-campylobacter infection

Polyneuritis

- Reactive arthritis

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Sepsis-3

Life-threatening organ dysfunction (q-SOFA>2) due to dysregulated host response to infection (usually bacterial)

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Sepsis mechanism

Breach of integrity of host barrier
Bacterial toxin release
Mediator release
Effects of excessive mediators
- Exotoxin: Th1 -> pro-inflammatory -> septic shock + MODS
- Endotoxin: Th2 -> anti-inflammatory -> immunoparalysis

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qSOFA

Systolic BP < or = 100 mmHg
Altered mental status
RR > or = 22

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Sepsis investigations

Bloods:

FBC
LFTs
Coagulation
U&Es
CRP
lactate

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Sepsis-6

ABCDE
Take 3:
- Blood cultures
- Serum lactate
- Urine output 
Give 3:
- IV antibiotics
- IV fluids 
- Oxygen

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Septic shock

Fluid refractory hypotension requiring vasopressors to maintain MAP >65 mmHg with serum lactate >2 mmol/L

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HIV virological mechanism

Viral surface glycoproteins (gp120) bind to CD4 glycoprotein on host cell surface
Virus penetrates host cell and releases RNA
Reverse transcription
Transcribed DNA incorporated into host genome

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HIV aetiology and spread

Sexual transmission
Blood exposure - IVDU, needlestick, transfusion
Vertical transmission
Organ donation

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HIV symptoms

Weight loss
Lymphadenopathy
Opportunistic infection: thrush, skin, oral
(Primary infection) Flu-like

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HIV investigations

Serum (acute/recovery phase) - antigen/antibody presence
CD4 lymphocyte count (<200 -> symptomatic)
PCR assay (viral load)

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HIV management

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Lifelong antiretroviral therapy

Reverse transcriptase inhibitors
Integrase inhibitor
Protease inhibitor

Prevention:

Education and behaviour
Pre- and post-exposure prophylaxis

Blood or body fluid exposure

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Hand hygiene
Encourage bleeding
Hep B > Hep C > HIV

Pyrexia of Unknown Origin

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> 38 degrees
- Caused by pyrogens acting on the hypothalamic thermoregulatory centre (vasoconstriction, decreased peripheral heat loss)

PUO classifications

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Classical
Nosocomial
Neutropenic
HIV associated

Staphylococcus aureus bacteraemia

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Gram +ve cocci in bloodstream (toxin or non-toxin mediated)
Any infection, broken skin
Examination: fever, hypotension, tachycardic/pnoea
Microscopy, cultures and imaging
IV antibiotic therapy

Outbreak

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2 or more cases of infection linked in time and place

IPC: prevent
Surveillance: detect and identify

Infection chain

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Infectious agent
Reservoir
Portal of exit
Transmission
Portal of entry
Susceptible host

Breaking infection chain

1. Diagnose and treat 2. Cleaning, disinfection and sterilisation 3. Hand hygiene, PPE, resp hygiene 4. Hand hygiene, PPE, cleaning etc, isolation, food safety 5. Hand hygiene, PPE, first aid, removal of devices (e.g. catheter) 6. Immunisations, education

Mode of transmission examples

- Direct contact: E. Coli - Aerosol: COVID, influenza - Ingestion: campylobacter, norovirus, C. diff - Vector-borne: Lyme, malaria

Influenza virology

RNA virus - Surface proteins haemagglutin antigen (attach host cell) and neuraminidase antigen (virion release) - Antigenic shift (H/N mutations)

Influenza transmission

Seasonal - winter - Airborne (droplet) - Contact

Influenza symptoms and complications

``` Incubation: 2-4 days - Fever - Cough - Fatigue/myalgia (weakness) - Headache - Sore throat Note: influenza like illness (WHO) - fever and cough in <10 days ``` Complications: acute bronchitis, pneumonia (CURB65), peri/myocarditis, polyneuritis

Influenza investigations

``` Viral nose/throat swabs Blood culture CXR Bloods ABG ```

Influenza management

- Oxygen if needed (<92%) - Neuraminidase inhibitors: Oseltamivir - Vaccination, PPE and hand/resp hygiene

Fungal infections

Opportunistic!! - Impaired immune system - Chronic disease - ICU

Fungal species

Aspergillus Candida Cryptococcus

Aspergillus infection

Invasive pulmonary aspergillosis - Acute, Sub-acute, Chronic (>3 mth), Allergic - Airborne

Aspergillosis symptoms

- Fever - Chest pain - Cough - Haemoptysis - Dyspnoea

Aspergillosis investigations

- Sputum culture - Biopsy - CT chest - Blood cultures - Bloods (IgG/E)

Candida infection

Candidiasis - Mucocutaneous: moist areas - Invasive (gut commensal) Risk Factors: - Antibiotic use - Impaired immune system - neonate, illness - Chronic disease - Medical devices/surgery

Candida investigations

- Fever + chills that doesn't improve with antibiotics - Bloods - Blood cultures - Clinical: oral candidiasis (thrush) etc

Cryptococcus infection

Cryptococcosis - Aerosol from environment - Organism can cross blood-brain barrier (cryptococcal meningoencephalitis)

Cryptococcosis symptoms

From asymptomatic to pneumonia (chest pain, cough, fever) - Headache - Confusion - Visual disturbances - Coma

Cryptococcosis investigations

CSF - Culture (and cryptococcus antigen) - Protein (high) - Glucose (low) Blood - Culture and antigen

Antifungals

IV (...azoles) 1. Amphotericin B formulations 2. Azoles 3. Echinocandins 4. Flucytosine

Zoonosis

Infections that are naturally transmitted between vertebrae animals and humans - Virus: rabies, ebola, yellow fever - Bacterias: salmonella, campylobacter, Toxoplasma - Parasites - Fungi

Rabies

Viral zoonose | - Bite of infected animal (dogs, bats etc)

Infection Flashcards

(44 cards)