Infectious Diseases Flashcards
What is the most common causative organism for infective endocarditis?
Staphylococcus aureus
Which pathogen is associated with poor dental hygiene in infective endocarditis?
Streptococcus viridans
Which pathogen is associated with prosthetic valves in infective endocarditis?
Staphylococcus epidermidis
Which pathogen is associated with colorectal cancer in infective endocarditis?
Streptococcus bovis
What are the risk factors of infective endocarditis?
Rheumatic valve disease (30%)
Prosthetic valves
Congenital heart defects
Intravenous drug users (IVDUs)
Dental work
Which valve is most commonly affected by infective endocarditis?
Mitral valve
Aortic > tricuspid > pulmonary
What are the symptoms of infective endocarditis?
Fever/sweats/chills/rigors
Malaise, arthralgia, myalgia, confusion, weight loss
Pyrexia, tachycardia, signs of anaemia
Clubbing
New valvular mumur
Haematuria
Vasculitis lesions
Splenomeagaly
What are the specific signs of infective endocarditis?
Roth spots
Osler nodes
Janeway lesions
Splinter haemorrhages
Which valve is affected in IVDU infective endocarditis?
Tricuspid
What investigations are performed in infective endocarditis?
Bloods -FBC, ESR, CRP
3 blood cultures 1 hour apart within 24 hours
Urgent transoeophageal echocardiogram
Dukes Classification
How many blood cultures are performed in the investigation of infective endocarditis?
3 blood cultures 1 hour apart within 24 hours
Aerobic bottle first before anaerobic
What is the initial blind therapy for infective endocarditis?
Native valve
amoxicillin, consider adding low-dose gentamicin
If penicillin allergic, MRSA or severe sepsis
vancomycin + low-dose gentamicin
If prosthetic valve
vancomycin + rifampicin + low-dose gentamicin
In addition to antibiotics what is added to management for infective endocarditis in prosthetic valve?
Anticoagulation
What are the complications of infective endocarditis?
Stroke (left-side)
PE (Right side)
Congestive heart failure
What are the features of UTIs?
Features dysuria urinary frequency urinary urgency cloudy/offensive smelling urine lower abdominal pain fever: typically low-grade in lower UTI malaise
What is the most common cause of UTI?
E.coli
Which pathogen can cause struvite stones in UTIs?
Proteus mirabilis
What are the risk factors for UTIs?
Age >50 years
Urine outflow obstruction -BPH, stones, strictures
Catheters
DM
Pregnancy
Immunosuppression
What are the signs and symptoms of pyelonephritis?
Rigours Flank pain Pyrexia Nausea and vomiting Acute confusional state
What are the signs and symptoms of cystitis?
Frequency, urgency Dysuria Haematuria Foul-smelling + cloudy urine Suprapubic pain or loin pain
What is the first-line investigation for urinary tract infections?
Dipstick urinalysis - positive nitrites/leukocytes/blood
Urine MC&S - via Mid-stream urine - DIAGNOSTIC
What do White cell casts in urine suggest?
Pyelonephritis
What ABx is prescribed in UTIs?
Trimethoprim (Avoid in pregnancy)
Nitrofurantoin
What is Malaria?
Infection with the protozoan plasmodium
What is the most common type of malaria?
Falciparum malaria
What are the symptoms of malaria?
Headaches Weakness Myalgia/Arthralgia Anorexia Cyclical fevers - paroxysmal of severe cold rigors followed by severe sweating
Signs
- Pyrexia
- Splenomegaly
- Haemolytic anaemia - dark urine
What are the investigations to diagnostically confirm Malaria?
Giemsa-stained thick and thin blood smears
Thick -detects parasites present
Thin - identifies species
What is the management of malaria?
Complicated/severe
- Artensunate
- Quinine
What are the main signs and symptoms of hepatitis?
Raised AST/ALT
Fever
Jaundice
What is the prodromal phase of viral hepatitis?
General fatigue Malaise Joint/muscle pain Low-grade fever GI upset- RUQ pain
What are the symptoms associated with the icteric phase of viral hepatitis?
Jaundice Pale stools Dark urine Pruritus Hepatomegaly RUQ pain
Which hepatitis is associated with chronic hepatitis?
B,C,D
How is HepA-E transmitted?
Faeco-oral transmission
Shellfish and contaminated water.
How is Hep B and C transmitted?
Sexual contact Blood borne Vertical transmission Needle-stick injury Associated with HIV
What is the management of acute viral hepatitis B?
Acute- supportive
What is the management for chronic viral hepatitis B?
Peginterferon Alpha-2-A
Antivirals (Tenofovir)
What is the management of chronic hepatitis C?
Sofobuvir
Daclatasvir
What do LFTs reveal in viral hepatitis?
Increased bilirubin Decreased albumin Raised ALT/AST Raised GGT Raised ALP
Clotting - Prolonged PT (INR) - A sensitive marker of significant liver damage
What radiological investigation is performed in diagnosing viral hepatitis?
Ultrasound scan
Which antibodies raise first in hepatitis A?
IgM
What investigation is performed to assess the degree of inflammation and liver damage in viral hepatitis?
Liver biopsy
Which hepatitis antibodies are raised in vaccinated Hep B?
Anti-HepB Surface antigen
Which hepatitis antibodies are raised in natural immune hepatitis B?
Anti-HbSAg
Anti HbC-Ag
Which hepatitis antibodies are raised in acute infection of HepB?
IgM anti-HbCAg
HbSAg
HbSAg + and Anti-HbCAg - suggests what?
Chronic infection
Which antigen is associated with chronic and acute hepatitis B?
HbSAg
What is gastroenteritis?
Inflammation of the gastrointestinal tract - caused by pathogens
What are the common viruses associated with gastroenteritis?
Norovirus
Rotavirus
What are the common bacteria associated with gastroenteritis?
Campylobacter Jejuni
E.coli
Salmonella
What are the symptoms of gastroenteritis?
Sudden onset diarrhoea Blood or mucous in the stool Faecal urgency Nausea/vomiting Fever + malaise Abdominal pain or cramps
Associated symptoms: Headache, myalgia, bloating, flatulence, weight loss, malabsorption
What is dysentery?
Blood in stool due to an infectious agent
Which infectious agents are associated with secretory diarrhoea?
Campylobacter Staph aureus Vibrio cholera E.coli Salmonella Bacillus cereus
What are the CHESS organisms responsible for causing dysentery (bloody diarrhoea)
Campylobacter/Clostridium difficile Haemorrhagic E.coli Entamoeba histolytica Shigella Salmonella
Which agents can potentiate C difficile?
Antibiotics (Second and third-generation cephalosporins and clindamycin)
PPI
Anti-peristaltic drugs
How is staph aureus diarrhoea caused?
Contaminated food 1-6 hours, short lived
How is bacillus cereus transmitted?
Reheated rice
Can cause cerebral abscess
How is E.coli caused?
Contaminated foods - associated with recent travel
How is salmonella transmitted?
Eggs, poultry, associated with constipation, multiplies in Peyer’s patches
What causative organism is associated with GBS?
Campylobacter
What strain causes haemorrhagic E.coli?
EHEC 0157:H7
What renal disorder is associated with ETEC?
Haemolytic uraemic syndrome
How is shigella transmitted?
Person-to-person contact
Poor sanitation
MSM
What examination findings are associated with gastreoenteritis?
Dry Mucous membranes, reduced skin turgor, cap
Reduced urine output - marker of dehydration
HR, BP - signs of shock
Temperature
What is the management for gastroenteritis (no systemic signs)?
Supportive therapy, bed rest, and electrolyte replacement with oral rehydration solution.
What is the management for gastroenteritis (systemic illness)?
Admit and give oral fluids
-Direct faecal smear, then culture
Definition of meningitis?
Inflammation of leptomeningeal (pia mater and arachnoid) coverings of the brain
Affects extremes of age
What are the most common bacterial causes of meningits?
Neisseria meningitidis
Streptococcus pneumoniae
Which is the most common viral of meningitis?
Coxsackie virus, HSV, enteroviruses
What type of bacteria is Neisseria meningitides?
Gram negative diplococci
What type of bacteria is streptococcus pneumonia?
Gram positive cocci
What is the classic triad of meningits?
Photophobia
Neck stiffness
Headache
What is the presentation of meningits?
Fever Tachycardia Hypotension Photophobia Neck stiffness Headache Non-blanching rash N&V
What does a non-blanching skin rash suggest in meningitis?
Meninogoccal stepicaemia
Neisseria meningitiidis
What is Brudzinki’s sign?
Passively flex at neck - severe neck stifness
What is Kernig’s sign?
Severe stiffness of the hamstrings and an inability to straighten the leg
What does a lumbar puncture reveal in bacterial meningitis?
Gram-negative diplococci
Numerous segmented neutrophils
What investigations are recommended in meningitis?
Two sets of blood cultures
-Imaging - CT to exclude intracranial pressure - to assess viability for lumbar puncture
What is the diagnostic investigation for meningitis?
Lumbar puncture - send the CSF sampling for MC&S and gram staining to confirm
What are the contraindications for a lumbar puncture?
Neurological signs suggested raised ICP
Superficial infection of the lP site
Coagulopathy
What CSF features are associated with bacterial meningitis?
Turbid
Very high-neutrophils
Raised protein
Low glucose
What features are associated with viral meningitIs (CSF)
Clear/cloudy appearance
High lymphocytes
Raised protein
Normal glucose
What features are associated with TB/fungal meningits?
Clear cloudy appearance - high lymphocytes
Raised protein
Low glucose
What is the first-line management for non-blanching rash/meningococcal septicaemia?
Admit/call an ambulance
Single-dose of IV benzylpenicillin
What ABx is prescribed in bacterial meningitis?
IV ceftriaxone
Consider corticosteroids - dexamethasone for bacterial meningitis
If the patient has affected consciousness in meningitis what should be given?
IV acyclovir (Suspect encephalitis)
What is the prophylaxis of meningitis?
Rifampicin or ciprofloxacin