Infectious disease Flashcards
What is sepsis
Body launches a large immune response
Get systemic inflammation that affects the functioning of organs
What is septic shock
When arterial BP drops enough to cause organ hypo-perfusion (systolic BP < 90 despite fluids)
Get buildup of lactate (organs undergoing anaerobic respiration)
Treatment: aggressive IV fluid regime, refer to HDU/ITU (for inotropes)
What is severe sepsis
Sepsis with organ dysfunction
Hypoxia, oliguria, AKI, thrombocytopenia, coagulation dysfunction, hypotension, hyperlactaemia
What are the risk factors for sepsis
Extremes of age
Chronic conditions
Immunosuppression
Recent surgery or trauma
Pregnancy or peripartum
Indwelling medical device
How might sepsis present
High NEWS
Signs of potential source (cellulitis, wound discharge, cough…)
Non-blanching rash
Reduced urine output
Mottled skin
Cyanosis
Arrhythmia
Tachycardia often first sign
Elderly often confused and drowsy
Immunosuppressed patients may have normal obs despite being very unwell
What investigations are needed for sepsis
FBC, U&Es LFTs, CRP, clotting
Blood cultures
ABG
Urine dip
CXR
Lumbar puncture (if suspect meningitis)
Go through sepsis 6
Give oxygen
Give broad spectrum antibiotics
Give IV fluids
Take lactate
Take blood cultures
Take urine output
How do chest infections typically present
Cough
Sputum production
Shortness of breath
Fever
Lethargy
Crackles
What are the most common causative organisms for chest infections
Streptococcus pneumoniae
Haemophilus influenzae
Which organisms cause chest infections in cystic fibrosis
Pseudomonas aeruginosa
Staphylococcus aureus
What are the causative organisms for atypical pneumonia
Legionella pneumophila
Chlamydia psittaci
Mycoplasma pneumoniae
Chlamydophila pneumoniae
Q fever (coxiella burnetii)
What are the antibiotic choices for chest infections
Community: amoxicillin
Alternatives: erythromycin, clarithromycin, doxycycline
Atypical bacteria: clarithromycin, levofloxacin, doxycycline
How might lower UTIs present
Dysuria
Suprapubic pain/discomfort
Frequency
Urgency
Incontinence
Confusion (in old/frail)
How might pyelonephritis present
Fever
Loin, suprapubic, and back pain
Feeling generally unwell
Vomiting
Loss of appetite
Haematuria
Renal angle tenderness
What would be the abnormalities on urine dipsticks in UTIs
Nitrites (gram negative break down nitrates to nitrites)
Leukocytes (rise in infection)
What are the causative organisms of UTIs
E coli
Klebsiella pneumoniae
Enterococcus
Pseudomonas aeruginosa
Staphylococcus saprophyticus
Candida albicans
What duration of antibiotics need to be used in UTIs
3 days: simple UTIs in women
5-10 days: immunosuppressed, anatomical abnormality, impaired kidney function
7 days: men, pregnant women, catheter-relates
What are the antibiotic choices in UTIs
Community: trimethoprim, nitrofurantoin
Alternatives: amoxicillin, cephalexin
How are UTIs managed in pregnancy
7 days: nitrofurantoin (first line, but avoid in 3rd trimester), amoxicillin, cefalexin
Higher risk of: pyelonephritis, premature rupture of membranes, preterm labour
What are the NICE guidelines for managing UTI pyelonephritis
In community, 7-10 days of: cefalexin, co-amoxiclav, trimethoprim, ciprofloxacin
How might skin/soft tissue infections present
Erythema
Hot
Tense
Thickened
Oedema
Bullae
Golden-yellow crust (staph aureus infection)
What are the causes of skin/soft tissue infections
Staph aureus
Group A strep (mostly strep pyogenes)
Group C strep (mostly strep dysgalactiae)
MRSA
What is the Eron classification
NICE assessment of severity of cellulitis
Class 1: no systemic toxicity or comorbidity
Class 2: systemic toxicity or comorbidity
Class 3: significant systemic toxicity or comorbidity
Class 4: sepsis, or life-threatening
When should skin/soft tissue infections be admitted
All class 3 or 4 infections (need IV antibiotics)
Consider for: frail, very young, immunocompromised
What are the antibiotics used for skin or soft tissue infections
Flucloxacillin (first line, IV or oral)
Clarithromycin
Clindamycin
Co-amoxiclav
What are the common causative organisms of intra-abdominal infections
E coli
Klebsiella
Enterococcus
Streptococcus
What is septic arthritis
Infection within a joint
An emergency (mortality of 10%)
Important complication of joint replacement
How might septic arthritis present
Single joint affected
Rapid onset
Hot, red, swollen, painful
Stiff, reduced range of motion
Systemic symptoms (fever, lethargy, sepsis)
Which bacteria commonly cause septic arthritis
Staphylococcus aureus
Neisseria gonorrhoea
Streptococcus pyogenes
Haemophilus influenzae
E coli
What are the differentials for septic arthritis
Gout
Pseudogout
Reactive arthritis
Haemarthritis
What is the management for septic arthritis
Low threshold for suspicion (until ruled out by joint fluid examination)
Follow local hot joint policy
Empirical IV antibiotics: until sensitivity testing comes back
3 - 6 weeks of antibiotics
Who is offered the influenza vaccine
> 65s
Young children
Pregnant women
Chronic conditions
Healthcare workers
Carers
How might influenza present
Fever
Coryzal symptoms
Lethargy and fatigue
Anorexia
Muscle and joint aches
Headache
Dry cough
Sore throat
How is influenza diagnosed
Nasal/throat swab
What is the management for influenza
Only for those at risk of complications: oral oseltamivir (5 days), inhaled zanamivir (5 days)
Need to start within 48 hours of symptoms
Can give post-exposure prophylaxis to high risk patients (10 days of antivirals)
What are the complications of influenza
Otitis media
Sinusitis
Bronchitis
Viral pneumonia
Secondary bacterial pneumonia
Worsening of chronic conditions
Febrile convulsions
Encephalitis
What are the viral causes of gastroenteritis
Rotavirus
Norovirus
Adenovirus
What are the bacterial causes of gastroenteritis
E coli (0157 produces shiga toxin, get haemolytic uraemic syndrome, bloody diarrhoea, avoid antibiotics (higher risk of HUS))
Campylobacter jejuni (travellers’ diarrhoea, can treat with azithromycin or ciprofloxacin)
Shigella (bloody diarrhoea, can get haemolytic uraemic syndrome, can treat with azithromycin or ciprofloxacin)
Salmonella (raw eggs/poultry, watery diarrhoea)
Bacillus cereus (rice, cramps, vomiting, diarrhoea, self resolves in 24 hrs)
Yersinia enterocolitica (from pork)
Staph aureus (eggs, dairy, meat)
Giardia (from animals, chronic diarrhoea, treat with metronidazole)
What is the management for gastroenteritis
Good hygiene
Immediately isolate patient
Microscopy, culture and sensitivity of faeces
Do a fluid challenge
Rehydration solution
Stay off work/school for 48 hrs after resolution)
Do not give antidiarrhoeals or antiemetics
What are some post-gastroenteritis complications
Lactose intolerance
IBS
Reactive arthritis
Guillain-Barre syndrome
What are the common causative organisms of bacterial meningitis
Neisseria meningitidis
Streptococcus pneumoniae
Group B strep
What is meningococcal septicaemia
When meningococcal bacteria infect the bloodstream
Causes a non-blanching rash
Can cause: DIC, subcut haemorrhage
How might bacterial meningitis present in adults
Fever
Neck stiffness
Vomiting
Headache
Photophobia
Altered consciousness
Seizures
How might bacterial meningitis present in neonates and babies
Non-specific signs and symptoms
Hypotonia
Poor feeding
Lethargy
Hypothermia
Bulging fontanelles
What are the NICE guidelines for lumbar puncture in neonates and babies
Under 1 month with a fever
1 - 3 months with fever and generally unwell
Under 1 with unexplained fever and features of serious illness
What are the special tests for bacterial meningitis
Kernig’s sign
Brudzinshi’s sign
What is the management for bacterial meningitis
Community: children need stat IM/IV benzylpenicillin before transfer to hospital
Hospital: blood cultures, lumbar puncture, send blood tests for meningococcal PCR, low threshold for treating
Antibiotics, steroids (reduce neurological damage)
Notifiable disease
What is the post exposure prophylaxis for bacterial meningitis
Single dose of antibiotics
Close prolonged contact with someone 7 days prior to onset of illness
What are the causes of viral meningitis
Herpes simplex
Enterovirus
Varicella zoster
What is the management for viral meningitis
Send CSF for viral PCR testing
Usually only supportive treatment needed
May need antivirals
What are the complications of meningitis
Hearing loss
Seizures and epilepsy
Cognitive impairment
Memory loss
Focal neurological deficits
What is the disease course of TB
Droplet inhalation spread
Granulomas containing bacteria from around the body
Active TB: active infection in various parts of the body
Latent TB: immune system encapsulates sites of infection, stop disease progression, becomes secondary TB when reactivates
If immune system unable to control disease: disseminated TB
Severe disease: miliary TB
How might TB present
Chronic, gradually worsening symptoms
Lethargy
Fever
Night sweats
Weight loss
Cough
Haemoptysis
Lymphadenopathy
Erythema nodosum
Spinal pain (Pott’s disease of the spine)
What are the risk factors for TB
Known contact with active TB
Immigrants from high TB areas
Close contact with countries with high TB rates
Immunosuppression
Homeless
Drug use
Alcoholics
Who is the BCG vaccine offered to for TB
Neonates from UK areas with high TB
Neonates with relatives from high TB countries
Neonates with family history of TB
Unvaccinated children and adults with close TB contacts
Unvaccinated children and young adults recently arrived from high TB country
Healthcare workers
What are the investigations for TB
Ziehl-Neelsen staining
Mantoux test: shows previous immune response, get a ‘bleb’ under skin, test for active disease if have positive result
Interferon-Gamma release assay (IGRA): mix blood sample with TB antigen, used to diagnose latent TB
CXR
Cultures
Nucleic acid amplification test
What would be seen on CXR in TB
Primary TB: patchy consolidation, pleural effusion, hilary lymphadenopathy
Reactive TB: patchy or nodular consolidation with cavitation, usually in upper zones
Disseminated miliary TB: ‘millet seeds’ uniformly throughout lung fields
What is the management for latent TB
No treatment in healthy people
If at risk of reactivation: isoniazid and rifampicin for 3 months, or rifampicin for 6 months
What is the management for acute TB
RIPE
Rifampicin for 6 months (causes red urine/tears and hepatotoxicity)
Isoniazid for 6 months (causes peripheral neuropathy and hepatotoxicity)
Pyrazinamide for 2 months (causes gout and hepatotoxicity)
Ethambutol for 2 months (causes colour blindness and reduced visual acuity)
Which cells does HIV destroy
CD4+ T helper cells
How is HIV transmitted
Unprotected anal, vaginal or oral sex
Vertical transmission
Open wound exposure to infected blood or bodily fluids
What is AIDS-defining illness
Due to end-stage HIV infection
CD4 count drops so low that get opportunistic infections and malignancies
How can HIV be tested for
Antibody blood test (P24 antigen)
Patients can self-sample (get online kit, post sample)
PCR for HIV RNA (can get a viral load)
What monitoring is needed for HIV
Viral load
CD count: low count = higher risk of opportunistic infection, 500 - 1200 = normal, < 200 = end stage HIV/AIDS
What treatment is needed for HIV
Give antiretroviral therapy (ART) irrespective of viral load
Aim: get CD4 normal CD4 count and undetectable viral load
HAART medications
Prophylactic co-trimoxazole
Closely monitor for cardiovascular disease
Yearly smear tests
Avoid live vaccines
What are the medications in HAART management of HIV
Protease inhibitors
Integrase inhibitors
Nucleoside reverse transcriptase inhibitors
Non-nucleoside reverse transcriptase inhibitors
Early inhibitors
How might malaria present
Incubation of 1-4 weeks
Fever, night sweats, rigors
Malaise
Myalgia
Headache
Vomiting
Pallor (due to haemolytic anaemia)
Hepatosplenomegaly
Jaundice (due to rupturing RBCs)
How is malaria diagnosed
Malaria blood film (3 samples sent over 3 consecutive days, 48 hour cycle of malaria being released into bloodstream)
Often see deranged bloods (anaemia, thrombocytopenia, leukopenia, abnormal LFTs)
How is malaria managed
Falciparum malaria: admit to treat (deteriorate very quickly)
Oral options for uncomplicated malaria: riamet, malarone, quinine sulphae, doxycycline
IV options for severe disease: artesunate, quinine dihydrochloride
What are the complications of falciparum malaria
Cerebral malaria
Seizures
Reduced consciousness
AKI
Pulmonary oedema
DIC
Severe haemolytic anaemia
Multiorgan failure
Death
What are some antimalarials that may be used for prophylaxis
Malarone
Mefloquine
Doxycycline
What are some common infection presentations after travel
Fever
GI symptoms
Jaundice
Reticuloendothelial changes
Respiratory symptoms
Rash
What are some common causes of fever in a returned traveller
Malaria
Dengue fever
Typhoid fever
Which travel infections occur at 0 - 10 days
Dengue
Rickettsia
Viral
GI
Which travel infections occur at 10 - 21 days
Malaria
Typhoid
Primary TB
Which travel infections occur at > 21 days
Malaria
Chronic bacterial infections
TB
Parasitic infections
Where is typhoid fever common
Asia
South America
How might typhoid fever present
Fever
Anorexia
Malaise
Vague abdominal discomfort
Altered bowel habits
Dry cough
Pulse-temperature dissociation
Hepatosplenomegaly
Rose-spots on skin
What investigations are needed for typhoid fever
FBC (leucopenia, lymphopena)
CRP (raised)
Isolate organism from cultures
What is the management for typhoid fever
Antibiotics
What is the definition of pyrexia of unknown origin
Temperature > 38 on multiple occasions
Illness for > 3 weeks
No diagnosis despite > 1 week of inpatient investigations
What are the common causes of pyrexia of unknown origin
Infective (TB, abscess, infective endocarditis, brucellosis)
Autoimmune/connective tissue (adult onset Still’s disease, temporal arteritis, Wegner’s granulomatosis)
Neoplasia (leukaemia, lymphoma, renal cell carcinoma)
Other (drugs, VTE, hyperthyroidism, adrenal insufficiency)
Who should be screened for basic STIs
All known to have an STI
All requesting a test
All known to be at high risk
