Infectious Diseases Flashcards by Harroop Bola

What is the most common causative organism for infective endocarditis?

Staphylococcus aureus

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Which pathogen is associated with poor dental hygiene in infective endocarditis?

Streptococcus viridans

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Which pathogen is associated with prosthetic valves in infective endocarditis?

Staphylococcus epidermidis

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Which pathogen is associated with colorectal cancer in infective endocarditis?

Streptococcus bovis

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What are the risk factors of infective endocarditis?

Rheumatic valve disease (30%)

Prosthetic valves

Congenital heart defects

Intravenous drug users (IVDUs)

Dental work

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Which valve is most commonly affected by infective endocarditis?

Mitral valve

Aortic > tricuspid > pulmonary

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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

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What are the specific signs of infective endocarditis?

Roth spots
Osler nodes
Janeway lesions
Splinter haemorrhages

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Which valve is affected in IVDU infective endocarditis?

Tricuspid

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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

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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

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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

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In addition to antibiotics what is added to management for infective endocarditis in prosthetic valve?

Anticoagulation

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What are the complications of infective endocarditis?

Stroke (left-side)
PE (Right side)
Congestive heart failure

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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

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What is the most common cause of UTI?

E.coli

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Which pathogen can cause struvite stones in UTIs?

Proteus mirabilis

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What are the risk factors for UTIs?

Age >50 years
Urine outflow obstruction -BPH, stones, strictures

Catheters

Pregnancy

Immunosuppression

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What are the signs and symptoms of pyelonephritis?

Rigours
Flank pain 
Pyrexia
Nausea and vomiting 
Acute confusional state

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What are the signs and symptoms of cystitis?

Frequency, urgency
Dysuria
Haematuria
Foul-smelling + cloudy urine
Suprapubic pain or loin pain

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What is the first-line investigation for urinary tract infections?

Dipstick urinalysis - positive nitrites/leukocytes/blood

Urine MC&S - via Mid-stream urine - DIAGNOSTIC

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What do White cell casts in urine suggest?

Pyelonephritis

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What ABx is prescribed in UTIs?

Trimethoprim (Avoid in pregnancy)

Nitrofurantoin

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What is Malaria?

Infection with the protozoan plasmodium

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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