Cardiovascular infections (and CNS)

Question 1

ENDOCARDITIS

Answer 1

Infection of the endocardium or devices within the heart
History: lethargy, malaise, night sweats, anorexia, weight loss. If heart failure too then orthopnea. Risk factors: known heart disease, pacemakers, prosthetic valve.
Signs: fevers, splinter haemorrhages, oslers nodes, jane-way lesions, roth spots, conjunctival haemorrhages, splenomegaly,
Cause: step and staph
Diganosis: 3 blood cultures and differnt times, echocardiography,
Treat: antimicrobials and surgery.

Question 2

MYCOTIC ANEURYSM

Answer 2

Aneurysms resulting from or secondarily infected by microorganisms
Pathogenesis: haematogenous seeding, trauma to arterial wall and direct contamination, extension from a contiguous infection focus, secondary to septic micro emboli.
Presentation: usually systemic symptoms of infection
Clinical features: no localising symptoms, painless swelling or painful swelling. Can present acutely if burst / leaking.
Aetiology: salmonella spp, staph aureus, strep, pseudomonas aeruginosa, E.coli
Diagnosis: imaging an detection of bacteria within tissue
Management: surgical removal/ structuring swelling/ antibiotics

Question 3

INFECTED DEEP VEIN THROMBOSIS

Answer 3

Can be seeded with bacteria during bacteraemia or directly infected eg IVDU into femoral vein.
Presentation: symptoms, signs of DVT And systemic infection and Respiratory symptoms.
Aetiology: Depends on mechanisms but commonly S.aureus, strep and anaerobes in IVDU
Diagnosis: 3 blood cultures

Question 4

BACTERAEMIA

Answer 4

Definition: Bacteria in the blood. Bacteraemia + symptoms of infection = bloodstream infection
Types: Transient, intermittent e.g. pneumonia and continuous e.g endocarditis.
It is distinct from sepsis, which is the host response to the bacteria.

Question 5

BACTERIAL MENINGITIS

Answer 5

Medical emergency. One of top 10 causes of death worldwide
Definition: refers to inflammatory process of leptomeninges and CSF. (meningoencephalitis of brain parenchyma + meninges)
Treat: give empiric antibiotics even before diagnosis
Classified:
Acute pyogenic: usually bacterial meningitis
Aseptic: usually viral meningitis
Chronic: TB, spirochetes and cryptococcus
Pathogenesis: Haematogenous spread most common eg arterial rout. Or direct implantation e.g traumatic or iatrogenic. Local extension: secondary to established infections often sinuses or mastoid. Or along peripheral nerves, usually viruses such as rabies, herpes zoster.
Clinical features: headache, neck stiffness, photophobia, fever, vomiting, rash, varying levels of consciousness.
Common in: neonates, elderly, immunosuppressed.

Question 6

bacterial meningitis cause in different ages

Answer 6

Neonates: Strep algalactiae and E.coli
3months -18 years: H.influenzae, N.meningitis, s.pneumoniae
18-50: s.penuomniae, N. meningitis
Elderly: S.pneumoniae
Lab diagnosis: Blood cultures, lumbar puncture and CSF for microscpy, EDTA blood for PCR.
CSF abnormalities in bacterial meningitis: LOW GLUCOSE, HIGH PROTEIN

Question 7

BRAIN ABSCESS

Answer 7

A brain abscess is a focal suppurative process within the brain parenchyma (pus in the substance of the brain)
Direct spread from contiguous supportive focus eg ear, sinuses or Haematogenous spread from a distant focus.
Cause: Streptococcus milleri, Staphylococcus aureus after surgery, Anaerobes, Gram –ve bacteria.
Symptoms: headache, focal neurological deficit fever, fever, nausea, vomiting, seizures, neck stiffness.
Management: drainage, reduce intracranial pressure, obtain pus for microbiology  antibiotics
Need to use antibiotics that can penetrate the blood brain barrier eg penicillin’s. Gentamicin cannot.
Steroids given eg dexamethasone 15 mins before antibiotics.
Ampicillin, Penicillin, Cefotaxime, Ceftazidime, and Metronidazole achieve therapeutic conc. in intracranial pus

Question 8

TB MENINGITIS

Answer 8

Chronic presentation: Higher incidence in immigrant populations. Insidious onset. High frequency of complications, cranial nerve palsies. CSF shows lymphocytic response but polymorphs present too.
- High protein and low glucose in CSF.
Higher levels in TB drug resistance so implications for treatment.

Question 9

SYPHILIS (NEUROSYPHILLIS)

Answer 9

CNS infection invasion occurs early in patients.
Asymptomatic neurpsyphilis can occur at any stage. Early symptomatic forms can cause acute meningitis or meningovascular. Late symptomatic forms can cause general paresis. Diagnosed by blood and CSF serology

Question 10

HERPES ENCEPHALITIS

Answer 10

Definition: acute inflammatory process affecting the brain parenchyma. Viral infection is most common cause.
Symptoms: fever, headache, behavioural changes, altered level of consciousness focal neurological deficits (more common in here than meningitis). Seizures. Focal signs of epopilpsy features. 30% mortality with treatment and 70% without.
Incidence: 3.5-7.4 per 100,000 persons per year
Cause: Herpes simplex virus, adenovirus, enterovirus, rabies, measles, mumps
Most common cause of sporadic encephalitis in previously healthy. May be evidence of herpes infection of skin

Question 11

VIRAL MENINGITIS

Answer 11

Affects children and young adults. Milder symtoms and signs and may start as respiratory or intestinal infection then viraemia.
CSF show raised lymphocyte count and protein and sugar usually normal.
Aeitology: Enterovirses eg Echo. Paramyxovirus: Mumps. Herpes simples, VZV, adenovirus, and HIV.

Question 12

RABIES

Answer 12

Acute, progressive viral encephalitis. Highest cause fatality of any infectious disease. One of the most ancient diseases. Fastest rate of mortality. Once symptoms set in- death is imminent.
Pathogenesis: Virus enters through bite, grows at trauma site for a week and multiplies, then enters nerve endings and advances toward the spinal cord.
Clinical phases: prodromal phase->fever, nausea, vomiting, headache, fatigue, pain at wound.
Furious phase->agitation, disorientation, seizures, twitching, hydrophobia
Dumb phase->paralysed, disorientated. Progress to coma phase resulting in death