INFECTIOUS DISEASE Flashcards
Name Gram +ve cocci
SSE
S Staphylococcus
S Streptococcus
E Enterococcus
Name Gram +ve bacilli/rods
Corny Mike’s List of Basic Cars
Corneybacteria
Mycobacteria
Listeria
Bacillus
Nocardia
Name Gram +ve anaerobes
CLAP
Clostridium
Lactobacillus
Actinomyces
Propionibacterium
Name Gram -ve cocci
NNM
Neisseria Meningitis
Neisseria gonorrhoea
Moraxella catarrhalis
Name Gram -ve bacilli/rods
Escherichia coli
Klebsiella pnuemoniae
Pseudomonas aeruginosa
Name Gram -ve coccobacilli
Haemophillus influenza
Antibiotics that inhibit bacterial cell wall synthesis?
Penicillin
Carbapenems
Cephalosporin
Vancomycin
Teicoplanin
Antibiotics that inhibit bacterial folic acid synthesis?
Trimethoprim
Sulfamethoxazole
Abx that stops bacterial nucleic acid synthesis ?
Metronidazole (v good for anaerobes)
Abx that inhibit bacterial protein synthesis ?
Macrolides
Clindamycin
Tetracyclines e.g. Doxyclycline
Gentamicin
Define sepsis
Life threatening organ dysfunction caused by a dysregulated host response to an infection
Define septic shock
Subset of sepsis with profound circulatory, cellular and metabolic abnormalities. Associated with greater risk of mortality than sepsis alone
Z2F: this is when arterial BP drops resulting in organ hypo-perfusion
How can septic shock be measured?
Systolic BP less than 90 despite fluid resuscitation
HYPERlactaemia - where lactate is >4 mmol/l
Pathophysiology of sepsis?
3 main parts: Cytokine - Coag - Lactate
Cytokines:
1) Pathogens recognised by macrophages, lymphocytes and mast cells
2) Cells release cytokines - cytokines activates other parts of immune system.
3) activation causes vasodilation
4) cytokines make endothelial lining of BV more permeable = so fluid leaks out —> get oedema and reduced intravascular vol.
5) oedema around BV means less O2 can reach tissues
COag:
6) Coag system is activated too!
7) fibrin deposits throughout circulation = also reducing tissue perfusion.
8) Platelets and clotting factors are used up to make clots —> causes thrombocytopenia, haemorrhages (so can’t make any other clots or stop bleeding). = DIC.
Lactate:
9) Get anaerobic resp as no O2 reaching tissues = so blood lactate rises. (as lactate is waste prod of anaerobic resp).
SEPSIS mnemonic
Slurred speech or confusion
Extreme shivering or muscle pain
Passing no urine (in 24hrs)
Severe breathlessness
I feel like I’m going to die
Skin mottled or discoloured
RF for developing sepsis?
V young or old - under 1, over 75
Chronic conditions e.g. COPD, DM
Immunosuppressed - chemo, immunosuppressants, steroids
Surgery, trauma, burns
Pregnancy, permpartum (just before or after birth)
Indwelling medical devices - catheter, cannula
Presentation of sepsis?
Scoring on NEWS.
What is involved?:
Temp, HR, RR, O2 sats, BP, consciousness level (AVPU)
Signs of sepsis on examination?
- Sources of infection - cellulitis, wound discharge, cough, dysuria
- Non blanching rash
- Mottled skin
- Cyanosis
- Arrythmia - new onset AF
Investigations for sepsis?
FBC - Wcc, neutrophils
U&Es - renal function, AKI
LFTs - liver function, liver is potential source of infection
CRP - assess inflammation
Coag screen/clotting - DIC
Blood cultures - bacteraemia
Blood gas - lactate, pH, glucose
Also could do:
- Urine dip and culture
- CXR
- CT scan abdo - suspect infection or abscess
- Lumbar puncture - suspect meningism
Management for sepsis
1) Assessed and treated within 1 hour of presentation
2) Perform sepsis 6:
Take blood lactate, take urine output, take blood cultures.
Give oxygen, broad spec abx, IV fluids
3) escalate - senior, HDU, ICU
Define neutropenic sepsis
Sepsis in pt with low neutrophil count of less than 1 x10(9) L
Causes of neutropenia in pts?
Anti- cancer chemo
Immunosupressants for RA - Hydroxychloroquine, Methotrexate, Sulfasalazine
Other immunosuppressants - Infliximab, Rituximab
Malaria treatment - Quinine
HyperThyroid treatment - Carbimazole
Why is neutropenic sepsis so urgent to manage?
Pts do not have immune system to fight infection - so are at high risk of death. Need emergency admission and management
Specific treatment for neutropenic sepsis
Immediate broad spec abx:
Piperacillin with tazobactam (tazocin)
What is osteomyelitis?
Inflammation of bone and bone marrow, usually caused by bacterial infections
Most common bacteria causing osteomyelitis?
Staphylococcus aureus
Risk factors for developing osteomyelitis?
Open fractures
Orthopaedic operations - esp w prosthetic joints
DM - esp w diabetic foot ulcers
Peripheral arterial disease
IV drug use
Immunosuppression
Presentation of osteomyelitis?
Fever
Gangrene
Pain and tenderness
Erythema
Swelling
Non-specific - w fever, lethargy, nausea and muscle aches
Investigations to do for suspected osteomyelitis?
MRI - best for establishing dx
XR - not good in early disease. Signs on XR = periosteal reaction, localised osteopenia, destruction of bone
FBC - raised WCC,
CRP, ESR
Blood cultures - causative organism and find abx sensitivity.
Management for osteomyelitis?
Surgical debridement of infected bone and tissues
ABx therapy- 4-6 weeks or 3-6 months in chronic osteomyselitis
If in prosthetic joint = prosthetic replacement surgery.
BNF recommendation for abx therapy of acute osteomyelitis?
6 weeks flucloxacillin +/- Rifampicin or fusidic acid for first 2 weeks
Alternative of flucloxacillin = Clindamycin. If MRSA related = vancomycin or teicoplanin
Name atypical bacteria that cause atypical pneumonia
Legions of Psittaci MCQs
Legionella pneumophila
Chlamydia psittacosis
Mycoplasma pneumoniae
Chlamydophila pneumoniae
Q fever - coxiella burneti
Abx options for MRSA?
Doxycycline
Clindamycin
Vancomycin
Teicoplanin
Linezolid
Cause of malaria?
Blood protozoan (single celled organism) parasite - Plasmodium species. Spread via bites from female Anopheles mosquito carrying the disease.
Types of Plasmodium species causing malaria?
Plasmodium falciparum
Plasmodium vivax
Plasmodium ovale
Plasmodium malariae
Presentation of malaria - symptoms?
NON SPECIFIC
Abrupt onset rigors
High fever
Sweats
Severe headache
Myalgia
Malaise
Nausea
Vomiting
Common bacteria that cause chest infections/pneumonia ( spell them too!)
Streptococcus pneumoniae
Haemophilus influenzae
Less common/opportunistic bacteria that cause chest infections/pneumonia and when?
Moraxella catarrhalis- in immunocompromised patients and those with chronic pulmonary disease
Pseudomonas aeruginosa- patients with CF or bronchiectasis
Staphylococcus aureus- In patients with CF
Main investigation for malaria?
Malaria blood film - need 3 to diagnose malaria
What do blood results for malaria show?
Anaemia
Thrombocytopenia
Leukopenia
Abnormal Liver enzymes
Chest infection presentation?
Cough
Sputum production
Fever
Lethargy
Crackles on the chest
Common bacteria that cause chest infections ( spell them too!)
Streptococcus pneumoniae
Haemophilus influenzae
Management for complicated or severe malaria?
(Dr Tom said this is more likely to come up in exam)
Has to be IV:
- Artesunate (most effective, but not licensed)
- Quinine dihydrochloride
- a parasite counts of more than 2% will usually need parenteral treatment irrespective of clinical state
- intravenous artesunate is now recommended by WHO in preference to intravenous quinine
- if parasite count > 10% then exchange transfusion should be considered
- shock may indicate coexistent bacterial septicaemia - malaria rarely causes haemodynamic collapse
Antibiotic for chest infection in community?
Amoxicillin or erythromycin or doxycycline
Complications from malaria by Plasmodium falciparum?
Cerebral malaria
Seizures
Reduced consciousness
AKI —> renal failure
Pulm oedema
DIC - disseminated intravascular coagulopathy
Severe haemolytic anaemia
Death
Blood film for malaria has been done. What other investigations to order?
Rapid antigen test
FBC - haemolysis, low HB, low platelets, thrombocytopenia
U&Es - AKI. high creatinine.
LFTs - ALT, jaundice (pre hepatic)
Glucose - reduced
Coagulation screen
Head CT if CNS symptoms - confusion - can see bleeding or signs of cerebral malaria
CXR - see ARDS
Management for uncomplicated malaria?
Admit P falciparum pts for treatment
Discuss with local ID unit
Oral options as follows:
1 Artemether with lumefantrine (called Riamet)
2 Proguanil and atovaquone (Malarone)
3 Quinine sulphate
4 Doxycycline
Management for complicated or severe malaria?
(Dr Tom said this is more likely to come up in exam)
Has to be IV:
- Artesunate (most effective, but not licensed)
- Quinine dihydrochloride
Main management for malaria with Plasmodium falciparum?
Admit
IV artesunate treatment
Monitor for complications.
Blood film for malaria has been done. What other investigations to order?
Rapid antigen test
FBC - haemolysis, low HB, low platelets, thrombocytopenia
U&Es - AKI. high creatinine.
LFTs - ALT, jaundice (pre hepatic)
Glucose - reduced
Coagulation screen
Head CT if CNS symptoms - confusion - can see bleeding or signs of cerebral malaria
CXR - see ARDS
Malaria prophylaxis advice to give pts?
Know where is high risk
Mosquito spray
Mosquito nets and barriers when sleeping
Antimalarial medication.
Exam patient with Chlamydophila pneumoniae?
School aged child with mild- moderate chronic pneumoniae and wheeze
Q fever exam patient?
Farmer with flu like symptoms
Q-fever linked to animal exposure and their bodily fluids
Chlamydia psittaci exam pt?
Parrot owner- contracted from infected birds
Define meningitis
Inflammation of the meninges
Gram stain of Neisseria meningitidis?
Gram negative diplococci
Symptoms of meningitis?
Signs of meningitis?
Symptoms: fever, headaches, photophobia, nausea and vomiting, seizures, drowsiness,
Signs: purpuric rash (non-blanching), neck stiffness
Common bacterial causes of meningitis in 6 years - 60 years?
Neisseria meningitidis
Streptococcus pneumoniae
Causes of meningitis? (i.e which pathogen groups?)
Viral
Bacterial
Fungal
Parasitic (v rare)
Bacterial meningitis is most clinically significant form because of its high mortality and morbidity
Most common bacterial cause of meningitis in neonates (0-3m)?
Group B Streptococcus (usually contracted during birth Group B strep that live harmlessly in the vagina).
Name of special tests to look for meningeal irritation?
Kernigs test
Brudzinki’s test
Describe Kernig’s test
Lying pt on back
Flex one hip and knee to 90deg
Slowly straighten knee while keeping hip flexed at 90deg
This creates stretch in meninges. If meningitis is present = spinal pain, or resistance to movement
Describe Brudzinki’s test
Pt lays flat on back
Examiner lifts pt’s head and neck off the bed and flex pt’s chin to chest
If meningitis is present = cause involuntary flex of hips and knees.
Most common cause of meningitis in older people ?
Listeria monocytogenes
Viral causes of meningitis?
Herpes simplex virus
Enterovirus
Varicella zoster virus
Causes of non-infective meningitis?
Malignancy (leukaemia, lymphoma and other tumours)
Chemical meningitis
Drugs (NSAIDs, trimethoprim)
Sarcoidosis
Systemic Lupus Erythematosus
Behcet’s disease
Investigations for meningitis?
Nice guidelines:
FBC
CRP
Coag screen
Blood culture
Whole-blood PCR
Blood glucose
ABG/VBG
Lumbar puncture - CSF analysis (if no signs of raised ICP)
Initial management of bacterial meningitis?
2g of IV ceftriaxone (or cefotaxime) twice daily.
Add IV amoxicillin if neonate or older person
Also require dexamethasone with 1st dose
Management of meningococcal meningitis?
Management of pneumococcal meningitis?
MM: Intravenous benzylpenicillin or ceftriaxone (or cefotaxime)
PM: IV ceftriaxone
If penicillin allergic = chloramphenicol IV
Management of meningitis with non-blanching rash in community setting before hospital transfer?
IM benzylpenicillin
Complications of meningitis?
Septic shock
DIC
Coma
Subdural effusions
SIADH
Seizures
Delayed complications : Sensorineural Hearing loss (most common), cranial nerve dysfunction, hydrocephalus, intellectual deficits, ataxia, blindness
Death
Patient with TB has insidious onset of personality change and headache. Also has N&V. What is top differential?
TB meningitis
Why does pt with miliary TB need lumbar puncture?
Exclude TB meningitis
Characteristics of CSF with bacterial meningitis:
Appearance?
Protein level?
Glucose level?
WCC?
Culture?
Appearance - cloudy
Protein level - high >1g
Glucose level - low; less than half of plasma.
WCC - neutrophils, 1000+
Culture - bacteria - diplococci, Gram -ve
Characteristics of CSF with viral meningitis:
Appearance?
Protein level?
Glucose level?
WCC?
Culture?
Appearance - clear (sometimes cloudy)
Protein level - normal/slightly raised
Glucose level - 60-80% of plasma
WCC - lymphocytes, 1000+
Culture - no bacteria culture
Characteristics of CSF with TB meningitis:
Appearance?
Protein level?
Glucose level?
WCC?
Appearance - clear, slightly cloudy. Fibrin web may develop.
Protein level - high >1g
Glucose level - low
WCC - lymphocytes, 1000+
Encephalitis features?
Fever, headache, psychiatric symptoms, seizures, vomiting
Focal features e.g. aphasia
Causes of encephalitis?
HSV-1 responsible for 95% of cases in adults
Where does encephalitis typically affect?
Temporal and inferior frontal lobes
Investigations + results for encephalitis?
CSF: lymphocytosis, elevated protein
PCR for HSV
Imaging: MRI is best- medial temporal and inferior frontal changes
Imaging normal in 1/3 of pts
ECG pattern: lateralised periodic discharges at 2Hz
Managment of encephalitis?
IV aciclovir should be started in all cases of suspected encephalitis
Prognosis of encephalitis?
Prompt treatment: 10-20% mortality
Untreated: 80% mortality
Aciclovir side effects?
Generalised fatigue/malaise (common)
Gastrointestinal disturbance (common)
Photosensitivity and urticarial rash (common)
Acute renal failure
Haematological abnormalities
Hepatitis
Neurological reactions
When should you suspect encephalitis?
Sudden onset behaviour changes, new seizures and unexplained acute headache with meningism
TB drug most likely to hepatotoxicity
Pyrazinamide
When is staph aureus likely to cause pneumonia?
After influenza
What causes diabetic foot disease?
secondary to neuropathy and peripheral artery disease
Why is diabetes a RF for peripheal arterial disease?
diabetes is RF for both microvascular and macrovascular ischaemia
Presentation of diabetic foot infection?
Neuropathy: loss of sensation
Ischaemia: lack of foot pulses, reduced ABPI, intermittent claudication
Complications: calluses, ulceration, cellulits, gangrene, osteomyelitis
What is low risk for diabetic foot disease?
No deformity, just calluses alone
What is moderate risk for diabetic foot disease?
deformity or
• neuropathy or
• non-critical limb ischaemia
What is high risk for diabetic foot disease?
Previous ulceration, previous amputation, on RRT, neuropathy + non-critical limb ischaemia, neuropathy + callus AND/OR defomity, non-critical limb ischaemia + callus AND/OR deformity
What is ankle brachial pressure index?
ratio of systolic BP in the lower legs to arms
What are the interpretations of ABPI?
> 1.2: may indicate calcified, stiff arteries. This may be seen with advanced age or PAD
- 0 - 1.2: normal
- 9 - 1.0: acceptable
< 0.9: likely PAD. Values < 0.5 indicate severe disease which should be referred urgently