Crash Course: Endocarditis, GI, UTI, SSI Flashcards
Define infective endocarditis
Infection, typically bacterial, of the endocardium
How is infective endocarditis classified by onset?
Subacute: classic indolent presentation
Acute: rapid onset, present septic
Prosthetic: high-risk 1-2m following valve replacement
How is infective endocarditis classified by valve affected?
L more common than R
Prosthetic valves are higher risk
TRICUSPID (R) affected in IVDU
What are the 3 classical signs of infective endocarditis?
Pyrexia of unknown origin
Constitutional Sx
New regurgitant murmur
What embolic phenomena manifest in infective endocarditis?
JANEWAY lesions: painless
SPLINTER HAEMORRHAGES
Septic emboli to brain, spleen, kidney- splenomegaly, haematuria
What immune phenomena occur in infective endocarditis?
ROTH spots
OSLER nodes: PAINFUL
Glomerulonephritis
What is the most common organism causing infective endocarditis in the UK vs the developing world?
UK: Staphylococcus aureus
DW: Streptococcus viridans
Which organism causing infective endocarditis is associated with recent prosthetic valve surgery?
Staphylococcus epidermidis
Which organism causing infective endocarditis is associated with colon tumours? Thus what investigations should be performed?
Streptococcus bovis
If culture +ve for S Bovis do colonoscopy
Which organisms causing infective endocarditis are culture negative?
HACEK organisms
Haemophilus
Aggregatibacter
Cardiobacterium
Eikenella
Kingella
Which organism causing infective endocarditis is associated with exotic birds?
Chlamydia psittaci
Which organism causing infective endocarditis is associated with farm animals?
Coxiella burnetti
Which organism causing infective endocarditis is associated with unpasteurised dairy?
Brucella spp.
What is the criteria used for diagnosing Infective endocarditis?
Duke criteria
2 Major
or
1 major + 3 minor
or
5 minor
What are the major criteria for diagnosing infective endocarditis?
BC’s +ve for infective endocarditis (at least 2 cultures, with typical organism)
Evidence of endocardial involvement on USS: new regurgitation + vegetation
What antibiotic regimen is used for infective endocarditis?
Initial ‘blind’: Amoxicillin + Gentamicin
S. aureus: Flucloxacillin + Vancomycin + Rifampicin
S. viridans: Benzylpenicillin
Give 4 indications for surgery in infective endocarditis
Continuing to worsen on Abx
Acute heart failure
Aortic root abscess: IE in aorta + developed abscess, suggested by PR prolongation
Prosthetic valve disease
What is non-infective endocarditis?
Endocardial vegetations without infection:
Mucin-producing adenocarcinomas (esp. Pancreatic adenocarcinomas)
SLE/ APLS = Libman-Sacks endocarditis
How can GI infection presentations be broadly split?
Infections limited to secretory GI Sx
Infections causing inflammation in the GI tract – dysentery
Infections causing systemic Sx
Give 4 causes of secretory GI disease. What is each associated with?
Bacillus cereus: Reheated RICE
Staphylococcus aureus: BBQ, short incubation as Sx caused by preformed toxin
Escherichia coli: Traveller’s diarrhoea
Vibrio cholera: Ricewater stool, comma- shaped bacterium
What is dysentery?
Bloody stool
Which organisms are associated with dysentery?
CHESS
Campylobacter jejuni: BBQs, longer incubation
Haemorrhagic E.coli
Entamoeba histolytica (Amoeba)
Salmonella enteritides: poultry, eggs
Shigella spp
Other than CHESS organisms, what can cause dysentery?
Yersinia enterocolitica
Non bloody or more often bloody diarrhoea
Often causes terminal ileitis + adenitis- can resemble appendicitis (RLQ pain)
Give 3 features of GI infection presentation due to Entamoeba histolytica
Dysentery
Chronic diarrhoea
Liver abscess
What is seen on histology in Entamoeba histolytica infection?
Flask shaped ulcers
Anchovy paste in abscess
What is used to treat Entamoeba histolytica?
Metronidazole
Give 2 features of GI infection presentation due to Giardia lamblia
Chronic diarrhoea
Malabsorption
What is seen on histology in Giardia lamblia infection?
Pear shaped trophozoites
What is used to treat Giardia lamblia?
Metronidazole
Which 2 organisms are associated with diarrhoeal illness in patients with HIV?
Cryptosporidium
Microsporidium spp
What causes Clostridium difficile?
Cephalosporins
Clindamycin
Ciprofloxacin
What investigations can be used to diagnose C difficile?
Stool C. difficile toxin
Visualise pseudomembrane
What is the treatment for first C. difficile infection? What is the treatment for first recurrence?
1st: Vancomycin PO
!st recurrence: Fidaxomicin PO
What is the treatment for further recurrence of C. difficile infection?
Consider faecal microbiota transplant
What is fulminant C difficile infection? What is the treatment for fulminant C. difficile infection?
In shock/ toxic megacolon
Vancomycin PO + IV metronidazole
Describe the appearance of C difficile on histology
Wet cornflake
Pseudomembranous colitis
In which scenarios is a UTI considered to be complicated?
Urinary tract abnormality
Pregnant
Immunocompromise
Instrumentation
How is UTI classified on severity?
Lower UTI/ cystitis: only affects bladder, classic Sx only
Pyelonephritis: infection ascends to kidney, fever, rigors, flank pain, systemically unwell
Pyonephrosis: pyelonephritis with obstruction, not producing urine. Hydroureter + enlarged kidney on USS
What is seen on urine dipstick in UTI?
Leukocytes ± nitrites ± haematuria
Nitrites specific for coliform UTIs
If -ve for nitrites, could still have a UTI, but probably not E coli
What is diagnostic of UTI on MC+S?
> 10^4 colony-forming units/ml any organism
> 10^3 colony-forming units/ml E. coli or Staph. saprophyticus
When is renal tract imaging performed in UTI?
if concern for complicated UTI
What could contaminate MC+S in potential UTI?
Epithelial squamous cells
Mixed growth
Organisms that don’t make sense e.g. S aureus
What are fried egg cells on MC+S? What are they indicative of?
Epithelial cells
Indicative of contamination
Why should you avoid urine dipsticks for diagnosing UTI in >65s?
Less reliable
Majority have bacteruria without infection/ Sx
Abx not indicated, may cause harm e.g. C diff risk
What is the most common cause of UTIs?
Escherichia coli
Which patient group is Staphylococcus saprophyticus associated with?
Young healthy women
What is Proteus mirabilis associated with on MC+S?
Struvite stones- affinity for calculi
What is Klebsiella aerogenes associated with on MC+S?
Catheterisation-adheres to plastic
Give 5 causes of sterile pyuria
TB
Sexually Transmitted Disease
Calculi
Catheterisation
Bladder neoplasm
What is the treatment for lower UTI?
Nitrofurantoin, Trimethoprim, Cephalexin
Uncomplicated: 3d
Complicated or Male: 7d
What is treatment for pyelonephritis?
Admit
IV Co-amoxiclav + Gentamicin
What is treatment for asymptomatic bacteriuria?
Do not treat unless pregnant
What must be checked before prescribing Trimethoprim for UTI?
Check if on Methotrexate (folate antagonist)
Do not give Trimethoprim if already on folate antagonist
What antibiotics can be used to treat UTI in pregnancy?
1st + 2nd Trim: Nitrofurantoin, Amoxicillin, Cephalexin
3rd Trim: Amoxicillin, (Trimethoprim) or Cephalexin
Why should Trimethoprim be avoided in the first trimester?
Teratogenic risk as it’s a folate antagonist
Why should nitrofurantoin be avoided at term?
Risk of neonatal haemolysis.
From most to least common give 4 causes of surgical site infection
Staphylococcus aureus
Escherichia coli
Streptococcus spp.
Pseudomonas
From most to least common give 3 causes of Osteomyelitis
Staphylococcus aureus
Streptococcus spp.
Escherichia coli
What organism is the most common cause of osteomyelitis and septic arthritis in sickle cell patients?
Salmonella
From most to least common give 3 causes of Septic arthritis
Staphylococcus aureus
Streptococcus spp.
Escherichia coli
From most to least common give 3 causes of prosthetic joint infection
Staphylococcus epidermidis (in first 2 months post-op)
Staphylococcus aureus
Streptococcus spp.
Escherichia coli
