Infectious diseases Flashcards
1
Q
What is infective endocarditis
A
Infection of endocardium or vascular endothelium of heart
2
Q
Risk factors for infective endocarditis
A
- IV drug use
- IV cannula
- Poor dental hygiene
- Dental treatment
- Skin and soft tissue infection
- Cardiac surgery
- Pacemaker
- Prosthetic valves (aortic and mitral)
- Congenital heart disease
3
Q
Causes of infective endocarditis
A
- Staph. Aureus IVDU, diabetes and surgery
- Staph. Viridans dental problems
- Strep. Mutans poor oral dentition
- Pseudomonas aeruginosa
- Candida albicans immunocompromise
- Staph. Epidermis prosthetic valve
4
Q
Presentation of infective endocarditis
A
- Headache
- Fever
- Malaise
- Confusion
- Night sweats
- Joint pain and abscesses
5
Q
Examination findings in infective endocarditis
A
- Finger clubbing
- Roth spots = retinal haemorrhages with white or clear centres
- Osler nodes = tender nodules in digits
- Murmur
- Janeway lesions = haemorrhages and nodules in fingers
- Anaemia
- Nail haemorrhages (splinter)
- Emboli
- Embolic skin lesions = black spots on skin
- Petechiae = small red/purple spots caused by bleeds in skin
6
Q
Investigations of infective endocarditis
A
- Use Dukes criteria
- Blood cultures = 3 sets from different sites over 24 hrs before antibiotics started
- Bloods CRP and ESR raised, Normochromic and normocytic anaemia, Neutrophilia
- Urinalysis = Look for haematuria
- CXR = Cardiomegaly
- ECG = Long PR interval at regular intervals
- Transoesophageal echo Visualising mitral lesions and possible development of aortic root abscess
7
Q
Duke’s criteria for infective endocarditis
A
Major criteria:
- Persistently +ve blood culture for typical organisms
- ECHO shows vegetation, dehiscence, abscess
- New valvular regurgitation murmur
- Coxiella burnetii infection
Minor criteria:
- Predisposing heart condition or IVDU
- Fever >38
- Emboli to organs/brain, haemorrhages
- GLomerulonephritis, Osler’s nodes, Roth spots, rheumatoid factor
- Positive blood cultures that do no meet specific criteria
8
Q
Diagnosis using Duke’s criteria
A
2 major
1 major and 3 minor
5 minor
Histological findings
+ve gram stain or cultures from surgery or autopsy
9
Q
Management of infective endocarditis
A
- Consult microbiologist
- Antibiotic treatment for 4-6 weeks
o Staphylococcus = vancomycin and rifampicin
o Not staph = penicillin (Benzylpenicillin and gentamycin) - Treat complications = stroke rehab, abscess drainage
- Surgery = Removing valve and replacing with prosthetic one
o Operate if infection cannot be cured with antibiotics
o Operate to remove infected devices
o Operate to remove large vegetations before they embolise
10
Q
Prevention of infective endocarditis
A
Good oral health
11
Q
Complications of infective endocarditis
A
- Stroke
- Pulmonary embolus
- Bone infections
- Kidney dysfunction
- MI
- Arrhythmia
- Heart failure
- Heart block
12
Q
Risk factors for tuberculosis
A
- Origination from high-prevalence country
- Immunosuppression (HIV/medications)
- Homeless, alcoholics, IVDU, prisoners
- Children
- Malnutrition
- Smoking
- Close contact to someone with active TB
13
Q
Causes of tuberculosis
A
- Mycobacterium tuberculosis (aerobic acid-fast bacilli)
- Mycobacterium bovis
- Mycobacterium africanum
- Mycobacterium microti
14
Q
Presentation of TB
A
- Fever and night sweats
- Anorexia and weight loss
- Productive cough (>3weeks) with occasional haemoptysis
- Malaise
- Breathlessness
- Pleuritic pain
- Hoarse voice = laryngeal involvement
- Clubbing
- Erythema nodosum
- Consolidation (pleural effusion)
- Lymphadenopathy
- Bone/joint pains, back pain and joint swelling
- Abdo/pelvic pain, constipation, bowel obstruction
- Sterile pyuria
15
Q
CXR in TB
A
Cavitation
Pleural effusion
Mediastinal/hilar lymphadenopathy
Parenchymal infiltrates in upper lobes
16
Q
Other investigations in TB
A
Sputum culture (x3) Ziehl-Neelsen stain for acid and alcohol-fast bacilli = turns bright red against blue background
17
Q
Screening tests for TB
A
- Mantoux test = previous vaccination, latent or active TB
o If positive then indicated immunity and thus contact with TB - Interferon gamma release assays
o Used when no features of active TB but positive Mantoux test to confirm latent TB
18
Q
Causes of false negative mantoux test
A
immunosuppression
sarcoidosis
lymphoma
extremes of age
fever
hypoalbuminaemia
anaemia
19
Q
Risk factors for developing active TB from latent TB
A
silicosis
chronic renal failure
HIV positive
solid organ transplantation with immunosuppression
IVDU
haematological malignancy
anti-TNF Tx
previous gastrectomy
20
Q
Management of active TB
A
- Notify PHE and contact tracing
- Rifampicin (6 months)
- Isoniazid (6 months)
- Pyrazinamide (2 months)
- Ethambutol (2 months)
21
Q
Side effects of rifampicin
A
red urine, hepatitis, drug interactions
22
Q
Side effects of isoniazid
A
hepatitis and peripheral neuropathy
o Prescribe pyridoxine (vit B6) as well
23
Q
Side effects of pyrazinamide
A
hepatitis, hyperuricaemia (gout), rash
24
Q
Side effects of ethambutol
A
colour blindness and reduced visual acuity
25
Treatment of latent TB
o 3m isoniazid (with pyridoxine) and rifampicin <35y if hepatotoxicity concern
o 6m isoniazid (with pyridoxine) HIV or transplant
26
Prevention of TB
- Active case finding to reduce infectivity
- Test for other infectious diseases = HIV, Hep B/C
- Vaccination = Neonatal BCG
27
Epidemiology of infective diarrhoea
- Highest prevalence in South Asia and Africa
- Tends to be children and elderly
28
Risk factors for infective diarrhoea
- Foreign travel
- PPI and H2 antagonist use
- Crowded area
- Poor hygiene
- Immunocompromised
- Reduced gastric acid secretion
29
Causes of infective diarrhoea
- Viral = Rotavirus (children), norovirus (adults), adenovirus, astrovirus
- Bacterial = campylobacter jejuni, E.coli, salmonella, shigella spp, C. diff
- Parasitic = Giardia lamblia, Entamoeba histolytica, Cryptosporidium
30
Presentation of infective diarrhoea
- Watery diarrhoea
- Blood usually indicates bacterial infection (Salmonella, E.coli and shigella)
- Vomiting
- Abdominal pain
- Viral = Fever, fatigue, headache, muscle pain
- Life-threatening Toxic megacolon and perforation
31
Investigations for infective diarrhoea
- Low MCV and/or Fe deficiency = coeliac disease or colon cancer
- High MCV if alcohol abuse or decreased B12 absorption = coeliac disease or Crohn’s
- Raised WCC if parasites
- Raised ESR and CRP indicate infection, Crohn’s, UC or cancer
- Stool culture if suspect bacteria, parasites or C.diff toxin
- Sigmoidoscopy with biopsy
32
Management of infective diarrhoea
- Oral rehydration and avoid high-sugar drinks in children
- Antibiotics (C.diff)
o Oral vancomycin for 10 days
o Oral fidaxomicin (if recurrent infection within 12 wks)
o Oral vancomycin + IV metronidazole (Life-threatening)
- Anti-motility agents = loperamide hydrochloride
- Anti-emetics = metoclopramide
33
Cause of enteric fever (typhoid)
Salmonella (transmitted via faecal-oral route)
34
Presentation of enteric fever
- Headache
- Fever
- Arthralgia
- Relative bradycardia
- Abdominal pain, distension
- Constipation ± diarrhoea
- Rose spots
35
Management of enteric fever
Ciprofloxacin
36
Complications of enteric fever
- Osteomyelitis (esp in sickle cell)
- GI bleed/perforation
- Meningitis
- Cholecystitis
- Chronic carriage
37
Risk factors for cholera
- Foreign travel to Africa, Asia, Middle East and South America
- Shellfish
38
Cause of cholera
Vibro cholerae (gram neg)
39
Presentation of cholera
- Profuse ‘rice water’ diarrhoea
- Dehydration
- Hypoglycaemia
- Hypokalaemia
- Metabolic acidosis
40
Management of cholera
- Oral rehydration therapy
- Antibiotics: doxycycline, ciprofloxacin
41
Risk factors for legionella
- Air conditioning systems
- Foreign holidays
42
Presentation of legionella
- Flu-like symptoms (fever)
- Dry cough
- Relative bradycardia
- Confusion
- Lymphopaenia
- Hyponatraemia
- Deranged LFTs
43
Investigations for legionella
- Urinary antigen
- CXR mid-to-lower zone predominance of patchy consolidation, pleural effusions
44
Management of legionella
Erythromycin/clarithromycin
45
Cause of malaria
- Plasmodium falciparum (severe)
- Plasmodium vivax (benign)
- Plasmodium ovale
- Plasmodium malariae
46
Risk factors for malaria
- Foreign travel
47
Protective factors for malaria
- G6PD deficiency
- HLA-B53
- Absence of Duffy antigens
- Sickle cell trait
48
Presentation of malaria
- Fever on alternating days
- Headache
- Myalgia
- Hepatomegaly
49
Cause of Hepatitis A
Infective hepatitis caused by RNA picornavirus via ingestion of contaminated food or water
50
Risk factors for hepatitis A
- Shellfish
- Travellers
- Food handlers
- Household contact
- Sexual contact
- Overcrowding and poor sanitation facilitate spread
- Injecting drug use
51
Pathophysiology of hepatitis A
- Spread via faecal-oral route
- Short incubation period = 2-6 weeks
- Causes acute hepatitis only (3-6 wks)
- 100% immunity after infection
52
Presentation of Hep A
- Flu-like prodrome
- Abdominal pain (RUQ)
- Nausea and vomiting
- Anorexia
- Fever
- Malaise
- Jaundice
- Tender Hepatosplenomegaly
53
Investigations for Hep A
- Bloods = low WCC, raised ESR
- LFTs = raised serum bilirubin, bilirubinuria and raised serum AST/ALT
- Viral markers = Hep A virus antibodies, Anti-HAV IgM
54
Management of Hep A
- Supportive treatment = resolves in 1-3 months
- Basic analgesia
- Avoid alcohol
55
Prevention of Hep A
- Vaccination + booster 6-12m later
o People travelling to or going to reside in areas of high prevalence
o Chronic liver disease
o Haemophilia
o MSM
o IVDU
o Occupational risk: lab workers, sewage workers, work with primates
- Good hand hygiene
56
Risk factors for Hep B
- Healthcare personnel
- Emergency and rescue teams
- CKD/dialysis patients
- Travellers
- Homosexual men
- IV drug users
57
Transmission of Hep B
- Blood borne transmission
o Needle stick/sharing needles (IVDU, tattoos)
o Sexual intercourse
o Blood products
o Vertical transmission = mother to child in utero/soon after birth
- Horizontal transmission
o Particularly in children
o Minor abrasions or close contact with others
o HBV can survive on household articles (toys, toothbrushes) for prolonged periods of time
58
Pathophysiology of hep B
- HBV (DNA) found in semen and saliva
- Following infection, 1-10% of patients not clear virus chronic Hep B cirrhosis and decompensated cirrhosis and liver failure
- Both cirrhosis and chronic infection can lead to hepatocellular carcinoma
- Chronic Hep B will result in continuing hepatocellular damage
59
Presentation of Hep B
- Nausea
- Fever
- Malaise
- Anorexia
- Arthralgia
- Rashes = urticaria and polyarthritis affecting small joints
- After 1-2 weeks jaundice
- Hepatosplenomegaly
60
Investigations for Hep B
- HBsAg present 1-6 months after exposure
- HBsAg presence for more than 6 months = carrier status/ chronic infection
- Anti-HBs = immunity (exposure or immunisation), negative in chronic infection
- Anti-HBc = previous or current infection
- IgM anti-HBc = acute or recent infection, present for 6m
- HbeAg = marker of infectivity
61
Management of acute Hep B
o Supportive + monitor LFTs
o Avoid alcohol
o Manage close contacts by giving human normal immunoglobulin for Hep B and vaccination
o Monitor HBsAg at 6 months to ensure there is full clearance and no progression
o Majority will get spontaneous resolution and will not progress to chronic infection
62
Management of chronic Hep B
o SC pegylated interferon-alpha 2A weekly = immunomodulatory
o Oral Nucleos(t)ide analogues daily (tenofovir)= inhibit viral replication
63
Prevention of Hep B
- Antenatal screening of pregnant mothers
- Screening and immunisation of sexual and household contacts
- Universal childhood immunisation
- Universal screening of blood products
- Sterile equipment and universal precautions in healthcare
- Immunisation of healthcare workers and other risk groups
64
Complications of Hep B
- Cirrhosis
- Liver failure
- Hepatocellular carcinoma
65
Hep D
RNA virus that can only survive in patient with hep B transmitted by blood-borne
66
Risk factors for Hep C
- People with haemophilia treated before screening of blood products was introduced
- IV drug users
- Men, HIV, high viral load, alcohol = more severe infection
67
Presentation of Hep C
- Most acute infections asymptomatic
- 10% have mild flu-like illness
- Jaundice
68
Investigations for Hep C
- HCV antibody = Present with 4-6 weeks
o False negative in immunosuppressed and in acute infection
- HCV RNA = current infection
- Rise in aminotransferases
- Fibroscan for cirrhosis
- Ultrasound for hepatocellular carcinoma
69
Management of Hep C
- Acute HCV = conservative if viral load falling
- If HCV RNA doesn’t decline then SC Pegylated interferon-alpha 2A/B + oral ribavirin
- Interferon based drugs have many mental side effects so direct acting antiviral treatment without interferon better
- Triple therapy with direct acting antivirals (oral)
o NS5A inhibitor = ledipasvir
o NS5B = sofosbuvir
70
Prevention of hep C
- No vaccine
- Previous infection doesn’t confer immunity = re-infected
- Screen blood products
- Precaution when handling body fluid
- Lifestyle modification = needle exchanges
- Treatment and cure of ‘transmitters’
71
Hep E
RNA virus transmitted by faecal oral route usually spread by contaminated water, rodents, dogs and pigs
72
Risk factors for meningitis
- Immunocompromised renal failure
- Extremes of age
- Pregnant
- Bacterial endocarditis
- Crowding
- Diabetes
- Malignancy
- IV drug abuse
73
Causes of meningitis
- Adults and children
o Neisseria meningitides = gram-neg diplococci
o Streptococcus pneumonia
o Haemophilus influenza
- Pregnant women/older adults Listeria monocytogenes
- Neonates E.coli, Group B haemolytic streptococcus
- Immunocompromised
o Cytomegalovirus
o Crytococcus neoformans
o TB
o HIV
o Herpes simplex virus
- Other viral causes: non-polio enteroviruses, mumps, measles
74
Presentation of meningitis
- Triad = Headache, neck stiffness and fever
- Acute bacterial infection
o Onset typically sudden
o Intense malaise, fever, rigors, severe headache, photophobia and vomiting = within hrs/mins
o Patient irritable and prefers to lie still
o Papilloedema
o Positive Kernig’s and Brudzinski’s sign can appear within hrs
o Non-blanching petechial + purpuric skin rash = meningococcal septicaemia
o Altered mental state with high fever = often absent
o Neonates = hypotonia, poor feeding, lethargy, hypothermia, bulging fontanelle
- Viral meningitis
o Benign, self-limiting condition lasting 4-10 hrs
o Headache may follow for some months
o Photophobia
o Confusion
75
Investigations for meningitis
- Blood cultures before lumbar puncture
- Lumbar puncture at L4
o If unable to perform within 30 mins give empirical antibiotics
o Can give headache, paresthesia, CSF leak and damage to spinal cord
o <1m presenting with fever
o 1-3m with fever and unwell
o <1y with unexplained fever and other features of serious illness
- CT pre LP = Focal neurological signs
- Blood tests = FBC, U+Es, CRP, serum glucose
- Throat swabs
- Pneumococcal and meningococcal serum PCR
- If there is non-blanching petechial or purpuric rash = meningococcal septicaemia
o No lumbar puncture due to risk of coning of cerebellar tonsils and raised ICA
76
Management of meningitis
- If suspect bacterial meningitis, start antibiotics before tests come back
- Community IM/IV benzylpenicillin, transfer to hospital
- Bacterial meningitis
o IV ceftriaxone or IV cefotaxime
o If under 3m/over 50/immunocompromised then add IV amoxicillin = Listeria
o Oral dexamethasone for 4 days = reduce cerebral oedema, hearing loss
o Consider IV vancomycin in returning travellers or penicillin resistant
o Meningitis septicaemia = IV benzylpenicillin
77
Prophylaxis for contacts of meningitis
o Oral ciprofloxacin state = all ages and pregnancy
o Oral rifampicin = all ages but not pregnancy
78
Complications of meningitis
- Hearing loss
- Seizures and epilepsy
- Cognitive impairment and learning disability
- Memory loss
- Focal neurological deficits = limb weakness and spasticity
79
Normal CSF fluid from LP
Clear
Protein 0.2-0.4
Glucose 0.6-0.8
WCC <5
Culture neg
80
Bacterial CSF fluid in LP
Cloudy
>1.5g/L
Glucose <0.5
WCC >1000 + neutrophils
Bacterial culture
81
Viral CSF in LP
Clear
Mildly raised/normal protein
Normal glucose
WCC >1000 + lymphocytes
Negative culture
82
What is encephalitis
Infection and inflammation of brain parenchyma (frontal and temporal lobes)
83
Causes of encephalitis
- Herpes simplex virus 1 (children)
- HSV 2 (neonates)
- Varicella zoster,
- EBV,
- Cytomegalovirus,
- HIV,
- Polio, mumps, measles, rubella
- Non-viral = Bacterial meningitis, TB, Malaria
- Autoimmune
83
Presentation of encephalitis
- Triad = fever, headache and altered mental status
- Altered consciousness
- Altered cognition
- Unusual behaviour
- Acute onset of focal seizures
- Myalgia, fatigue, nausea
- History = Travel, Animal bite
- Focal neurological deficit = Hemiparesis and dysphasia
- Raised ICP and midline shift may occur resulting in coning
- Coma
84
Investigations for encephalitis
- Lumbar puncture = CSF for viral PCR (elevated lymphocytes)
- MRI after LP
o Shows areas of inflammation and swelling, generally in temporal lobes in HSV encephalitis
o May be midline shifting due to raised ICP
- CT head if LP contraindicated = GCS <9, haemodynamically unstable, active seizures, post-ictal
- Electroencephalography = Shows periodic sharp and slow wave complexes
- Throat and vesicle Swabs identify causative organism
- HIV testing
85
Management of encephalitis
- Immediate treatment with anti-viral before results=
o IV acyclovir = HSV, VSV
o IV ganciclovir = cytomegalovirus
- Anti-seizure medication = primidone
- If meningitis suspected = Emergency IM benzylpenicillin
- Repeat lumbar puncture
- Other viral causes supportive management
86
Complications of encephalitis
- Lasting fatigue and prolonged recovery
- Change in personality or mood
- Changes to memory and cognition
- Learning disability
- Headaches
- Chronic pain
- Movement disorders
- Sensory disturbance
- Seizures
- Hormonal imbalance
