Infectious diseases Flashcards
Define sepsis
Large immune response to an infection, causing systemic inflammation and organ dysfunction
Define septic shock
- When arterial BP drops despite adequate fluid resus
- This causes organ hypoperfusion, leading to anaerobic respiration and lactate rises.
How is septic shock diagnosed ?
- Low mean arterial pressure (below 65 mmHg) despite fluid resuscitation (requiring vasopressors)
- Raised serum lactate (above 2 mmol/L)
How is septic shock managed on ITU when fluid resus is inadequate ?
- Vasopressors (e.g. noradrenaline)
- They cause vasoconstriction, increasing systemic vascular resistance and in turn MAP
what is an early sign of sepsis ?
Tachypnoea
what is the sepsis 6 done in anyone with suspected sepsis
- > 3 treatments : oxygen, empirical broad-spectrum Abx, IV fluids
-> 3 tests : serum lactate, blood cultures, urine output
what are the target SATs for anyone on oxygen ?
- 94-98%
- 88-92% in COPD
Presentation of a lower UTI (7)
- Dysuria
- Suprapubic pain
- Frequency
- Urgency
- Incontinence
- Cloudy or foul-smelling urine
- Confusion in older and frail patients
Most common cause of UTI
E. coli = gram-negative, anaerobic, rod shaped bacteria
When should a urine culture be sent over just a urine dipstick in UTI ? (5)
- Women aged > 65 years
- Recurrent UTI (2 episodes in 6 months or 3 in 12 months)
- Pregnant women
- Men
- Visible or non-visible haematuria
What does the results of a urine dipstick suggest based on leukocytes / nitrites
- Nitrities or leukocytes + RBCs = UTI
- Nitrites + leukocytes = UTI
- Nitrites only = UTI
- Leukocytes only = culture
How is a UTI managed in non pregnant women ? ?
- Check local Abx guideline
- Trimethoprim or nitrofurantoin for 3 days
- Send MSU culture if >65 yrs or visible / non visible haematuria
How is a UTI managed in a pregnanct woman ?
- Send MSU culture
- 7 day course !
- 1st = nitrfurantoin UNLESS 3rd trimester
- 2nd = cefalexin or amoxacillin (if sensitivities known)
what is the effect of nitrofurantoin and trimethoprim if given at the wrong time in pregnancy ?
- Nitrofurantoin = avoid in 3rd trimester = neonatal haemolysis
- Trimethoprim = avoid in 1st trimester = folate antagonist = neural tube defects
How is a UTI managed in man ?
- 7 days of nitrofurantoin / trimethoprim
- MSU culture
what is the management of asymptomatic bacteriuria in pregnancy women
- 7 day course of Abx
- MSU culture for test of cure
Clinical features of pyelonephritis (triad +3)
- Triad : fever, loin pain, N&V
- Loss of appeitite
- Haematuria
- Renal angle tenderness
how is pyelonephritis managed ?
- Should have SMU sent before
starting 7-10 days Abx - Cefalexin
- Co-amoxiclav / trimethoprim if culture results available
what is cellulitis and its most common causes (2) ?
- Infection of the skin and soft tissue
- Streptococcus pyogenes (most common - inc in DM)
- Staphylococcus aureus
How does cellulitis present ?
- Erythema
- Warm or hot to touch
- Swelling
- Systemically unwell : fever, malaise, nausea
- Bullae in severe disease
What is the eron classification of cellulitis
- Class 1 – no systemic toxicity or uncontrolled comorbidity
- Class 2 – systemic toxicity or comorbidity
- Class 3 – significant systemic toxicity or significant comorbidity
- Class 4 – sepsis or life-threatening infection
Management of eron class I cellulitis
- Oral flucloxacillin (Doxycycline if pen allergic)
Management of eron class III or IV cellulitis
- Admit
- Oral/IV co-amoxiclav, oral/IV clindamycin, IV cefuroxime or IV ceftriaxone
How is cellulitis managed in a pregnant woman ?
- Oral erythromycin
what kind of bacteria are streptococci and when are they clinically important ?
- Gram positive cocci
- Alpha haemolytic = streptococcus pneumoniae (pneumonia)
- Beta haemolytic = Group A streptococcus pyogenes -> cellulitis, impetigo, tonsilitis
what causes TB and what staining is required when culturing?
- Mycobacterium tuberculosis = “rod shaped acid-fast bacilli”)
- Zeihl-Neelsan staining = bright red against a blue background
Define the different outcomes when TB enters the body
- Immediate clearance of the bacteria
- Primary active tuberculosis = active infection after exposure
- Latent tuberculosis = presence of the bacteria without being symptomatic or contagious
- Secondary tuberculosis = reactivation of latent tuberculosis to active infection, usually occurs in the apex of the lungs when a pt becomes immunocomprimised
what are the 2 screening tests for latent TB ?
-> Mantoux test (>=6mm = +ve)
-> Interferon-gamma release assay (IGRA)
what is used to diagnose TB in active disease ?
- CXR
- Sputum smear : 3 samples and 50-80% sensitive
- Sputum culture = gold standard (more sensitive) but takes 1-3 weeks. Used to assess drug sensitivites
- NAAT - rapid diagnosis (1-2 days)
What are common findings on CXR in TB ?
- Primary tuberculosis - bilateral hilar lymphadenopathy.
- Reactivated tuberculosis = upper lobe cavitation (gas-filled spaces),
- Disseminated miliary tuberculosis = millet seeds uniformly distributed across the lung fields.
How is active TB managed ?
- R : Rifampicin for 6 mnths
- I : Isoniazid for 6 mnths
- P : Pyrazinamide for 2 mnths
- E : Ethambutol for 2 mnths
what should be prescribed alongside isoniazid ?
- Pyridoxine (vitamin B6) -> prevents peripheral neuropathy caused by isoniazid
How is latent TB managed ?
EITHER
- Isoniazid and rifampicin for 3 months
- Isoniazid for 6 months
Common SE of rifampicin
- Red / orange discolouration of urine / tears
Common SE of Isoniazid
Peripheral neuropathy
Common SE of pyrazinamide
- Hyperuricaemia = gout and kidney stones
Common SE of ethambutol
- Optic neuritis
what is the typical presentation of TB ?
- Usually causes pulmonary disease
- Cough
- Haemoptysis
- Lethargy
- Fever or night sweats
- Weight loss
- Lymphadenopathy
what is the typical presentation of malariua ?
- Fever (up to 41) spiking every 48 hours.
- Fatigue
- Myalgia
- Headache
- N&V
what is seen on examination in malaria ?
- Pallor due to the anaemia
- Hepatosplenomegaly
- Jaundice
What are the treatment options for severe or complicated malaria ?
- IV Artesunate (1st choice)
How is malaria tested for ?
- 3 thick & thin blood films at least 24hrs apart should be sent
- Thick films are used to calculate the parasitaemia
- Parasitaemia >2% is associated with increased chance of developing severe disease
what are the features of severe malaria in an adult (7)
- Schizonts on blood fim
- Parasitaemia >2%
- Hypoglycaemia
- Acidosis
- Temp >39
- Severe anaemia
Causes of meningitis in 0-3 mnths
- Group B Streptococcus (most common cause in neonates)
- E. coli
- Listeria monocytogenes
Causes of meningitis in 3mnths - 6 yrs
- Neisseria meningitidis
- Streptococcus pneumoniae
- Haemophilus influenzae
Causes of meningitis in 6 yrs - 60 yrs
- Neisseria meningitidis
- Streptococcus pneumoniae
Causes of meningitis in >60 yrs
Streptococcus pneumoniae
Neisseria meningitidis
Listeria monocytogenes
Causes of pneumonia in the immunosuppressed
Listeria monocytogenes
Define meningitis, meningococcal meningitis and meningococcal septicaemia
- > Inflammation of the meninges
-> Meningococcal meningitis : inflammation of meninges and CSF
-> Meningococcal septicaemia : bacterial infection is in the bloodsteam -> can lead to non blanching rash.
what are the common viral causes of meningitis ?
Enteroviruses (e.g., coxsackievirus)
Herpes simplex virus (HSV)
Varicella zoster virus (VZV)
HSV / VZV = aciclovir
What is the usual presentation of meningitis
- Fever
- Neck stiffness
- Vomiting
- Headache
- Photophobia
- Altered consciousness
- Seizures
what 2 tests suggest meningeal irritation ?
-> Kernig’s : flex one hip and knee to 90 degrees, then straighten knee keeping hip flexed. +ve = pain or resisted movement
- > Brudzinski’s : flexing chin to chest whilst laying flat = hips and knees flex involuntarily
CSF findings in bacterial meningitis
- Appearance : cloudy
- Protein : high
- Glucose : low
- WCC : high neutrophils
- Culture : bacteria
CSF findings in viral meningitis
- Appearance : clear
- Protein : normal or mildly raised
- Glucose : normal
- WCC : high lymphocytes
- Culture : negative
CSF findings in fungal meningitis
- Appearance : cloudy
- Glucose : low
- Protein : high
- WCC : high lymphocytes
Management of suspected meningitis with non blanching rash in community
IM benzylpenicillin
- <1yr = 300mg
- 1-9 yrs = 600mg
- > 10 yrs = 1200mg
management of pt with suspected meningitis without indication for delayed LP
- IV access → take bloods and blood cultures
- LP within 1st hr. (CI in the presence of a rash)
- IV antibiotics
- IV dexamethasone
Management of meningitis <3 mnths
Intravenous cefotaxime + amoxicillin (or ampicillin)
Management of meningitis >3mnths - 50 yrs
IV 2g ceftriaxone (cephlasporin)
Management of meningitis >50 yrs
- IV ceftriaxone + amoxicillin (risk of listeria)
what is deemed as a contact to someone with meningitis and what are they given ?
- Prolonged contact within 7 days before illness onset
- Single dose of ciproflaxacin (500mg)
5 complications of meningitis
- Hearing loss
- Seizures and epilepsy
- Cognitive impairment and learning disability
- Memory loss
- Focal neurological deficits, such as limb weakness or spasticity
What should CSF be sent for after doing a LP for suspected meningitis ?
- WCC
- Red cell count
- Protein
- Gram stain & culture
- Glucose
- Viral PCR
- Meningococcal & Pneumococcal PCR
What antibodies are associated with increased risk of c.diff
- Clindamycin
- Ciprofloxacin (and other fluoroquinolones)
- Cephalosporins
- Carbapenems (e.g., meropenem)
what are the features of c.diff
- Diarrhoea, nausea and abdo pain
- If severe = colitis = dehydration and systemic symptoms (tachycardia, hypotension).
what 2 tests re used for c.diff diagnosis
- Present of c.difficile antigen in stool (c.diff PCR)
- Presence of c.diff toxin in stool = diagnostic
what is first and second line management of c.diff
- Oral vancomycin for 10 days
- 2nd = oral fidaxomicin
How is recurrent c.diff infection managed ?
- within 12 weeks of symptom resolution: oral fidaxomicin
- after 12 weeks of symptom resolution: oral vancomycin OR fidaxomicin
how is life threatening c.diff managed
oral vancomycin AND IV metronidazole
(suggested by hypotension, ileus, toxic megacolon or CT evidence severe disease)
What can be considered in patients who’ve had 2 or more previous episodes of c.diff infection ?
faecal microbiota transplant
Give 4 complications of c.diff infection
- Pseudomembranous colitis
- Toxic megacolon
- Bowel perforation
- Sepsis
Most common organism found in central lime infections and is it coagulase negative or positve
- Staphylococcus epidermis
- Gram +ve cocci but coagulsae negative
Common presentation of bacillus cereus infection
- Short incubation period (24 hrs)
- Commonly caused by rice
- Crampy abdo pain, vomiting and diarrhoea
6 AIDs defining illnesses with underlying bacterual causes
- Gastreoenteritis caused by cryptosporidium parvum
- Pneumonia caused by pneumocystis jiroveci
- Loss of vision with cytomegalovirus retinitis
- HIV related encephalopathy
- Mycobacterium TB
- Invasive cervical cancer
Presentation of yellow fever
Flu like illness -> brief remission -> jaundice and haematemesis
What is the criteria for receiving varicella zoster immunoglobulin (VZIG) if exposed to chickenpox?
- Significant exposure to chickenpox or herpes zoster
- Clinical condition that increases the risk of severe varicella; this includes immunosuppressed patients, neonates and pregnant women
e.g. long-term steroids, methotrexate and other common immunosuppressants - No antibodies to the varicella virus
Cause of lyme disease
Spirochaete Borrelia burgdorferi and is sread by ticks
First line test for suspected lyme diease
ELISA antibodies to Borrelia burgorferi
Management if early lyme disase
Doxycycline
Amoxicillin if pregnanct
Management of disseminated lyme disease
Ceftriaxone
Early features of lyme disease
- Erythema migrans (bulls-eye rash)
- Headache, lethargy, fever, arthralgia
Late features of lyme disease
- Cardivascular : heart block, peri/myocarditis
- Neurological : facial nerve palsy, radicular pain, meningitis
Diagnosis and management of influenza
- Nasal / throat swab with PCR testing
- Tx : Oseltamivir (TAMIFLU)
2 viral causes of gastroenteritis
Rotavirus
Noravirus
Each cause most associated with :
- Foreign travel
- Raw eggs / poultry
- Old fried rice
- Small intestines of mammals
- Undercooked pork
- Campylobacter jejuni
- Salmonella
- Bacillus
- Giardia
- Yersinia
3 features of HUS
Anaemia
AKI
Low plts
2 causes of HUS
Shigella
E.coli 0157
4 complications of HUS
- Lactose intolerance
- GBS
- IBS
- Reactive arthritis
5 complications of malaria that would also then classify as severe malaeia
- Cerebral malaria (seizures, coma)
- Acute renal failure
- ARDS
- Hypoglycaemia
- DIC
Cause of type 1 and 2 necrotising fascitis
- 1 : Mixed anaerobes and aerobes (post surgery in diabetics) = most common
- 2 : Caused by strep pyogenes
Management of necrotising fascitis
IV ABx
Immediate surgical debridement
do you treat asymptomatic bacteria in catherised pts
No
what kind of vaccine is the BCG vaccine and what should be tested beforehand ?
- Live attenuated
- Tuberculin test
cause of pneumonia with cavitating lesion
Staphylococcus aureus
Who is affected by mycoplasma pneumoniae
younger people
Complication of mycoplasma pneumoniae
Cold autoimmune haemolytic anaemia
what antibiotics are used in animal and human bites
Co-amoxiclav
(doxycyline + metronidazole if pen allergic)
Skin finding in mycoplasma pneumonia
- Erythema multiforme = symmetrical target shaped rash with central blister
what are sewage workers at risk of ?
Leptospirosis
what kind of pneumonia does preceding influenza predispose to ?
Staphylococus aureus
Renal transplant + infection. Presenting with fever, bilateral pneumonia, derranged LFTs and lymphadenopathy. Likely cause ?
Cytomegalovirus
