Ch 14 - Infection & immunity Flashcards

1
Q

Bacterial meningitis: likely organisms in following age groups: neonates- 3 months (3), 1 month - 6 yrs (3), >6 yrs (2)

A

neonates - 3 months: GBS, listeria, E. coli
1 month - 6 yrs: N. meningitidis, H. influenza, S. pneumoniae
> 6yrs: N. meningitidis, H. influenza

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2
Q

Bacterial meningitis: features (8)

A
Fever, lethargy, poor feeding
Reduced consciousness
Purpuric non-blanching rash
Cushing's triad (ominous sign - reflex response to increased ICP): HTN + altered breathing pattern + bradycardia
Photophobia
Neck stiffness 
Kernig/ Brudzinski sign +ve
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3
Q

Bacterial meningitis: diagnosis is aided by LP; but when is LP contraindicated? (3)

A

Raised ICP signs e.g. coma, Cushing triad, papilloedema
Cardiorespiratory instability
focal neurology
Coagulopathy, thrombocytopenia

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4
Q

Describe the normal CSF characterstics seen on LP: appearance (1), WBCs (1), Protein (1), Glucose. Then do the same for meningitis: bacterial, viral, TB

A

Normal: clear, 0-5/mm3, 0.15-0.4 g/L, glucose > 50% of blood
Bacterial: turbid, raised polymorphs, increased protein, reduced glucose
Viral: clear, raised lymphocytes, normal/ slight increase in protein, normal/ slight decrease in glucose
TB: Turbid/viscous, raised lymphocytes, VERY HIGH protein & VERY LOW glucose

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5
Q

Management of Meningitis (bacterial) (2)

A

Febrile child with purpuric rash - dont risk it and give IM Benzylpenicillin + hospital transfer
IV Ceftriaxone

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6
Q

Viral meningitis: organisms (3), diagnosis (3)

A

Much less severe than bacterial & full recovery usual
Organisms: EBV, enterovirus, adenovirus, mumps (now less common due to MMR)
Diagnosis: PCR of CSF, stool cultrue, nasopharyngeal aspirate, throat swabs

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7
Q

Encephalitis: causes (4), features (3), management (2)

A

Causes: direct invasion of cerebrum by neurotoxic virus e.g. HSV, HHV6, post-infectious delayed brain swelling folowing abnormal immune response to an Ag (usually virus) e.g. chicknepox; HIV
Features - clinically cannot distinguish meningitis from encephalitis therefore treat both! Fevers, seizures, altered consciousness
Management - High dose IV acyclovir; HSV encephalitis can be devastating - CT/MRI may show temporal lobes atrophy

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8
Q

Toxic shock syndrome: 3 main characteristics, Causes (2), Features (4)

A

Triad: fever > 39, hypotension, diffuse erythematous macular rash.
Caused by S. Aureus or S. Pyogenes
Toxin can be released from infection at any site and acts as super ag.
Features - mucositis, D & V, renal impairment, liver impairment, clotting abnormalities

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9
Q

TSS: management (3)

A

Transfer to ICU
Surgical debridement of infected tissue
ABs - ceftriaxone & clindamycin (acts on bacterial ribsome to shut off toxin production)
IVIG - neutralize circulating toxin

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10
Q

PVL producing S. Aureus: what is the toxin (1), major risk of what (2)

A

Produces Panton-Valentine Leukocidin which causes recurrent skin + soft tissue infections
but can also cause NEC FASCIITIS & nec haemorrhagic pneumonia following an influenza like illness

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11
Q

Necrotizing Fasciitis/ Cellulitis: definition, Causes (2), Features (3), management (2)

A

Severe subcut infection from skin to fascia and muscle
Causes - PVL producing S. Aureues, S. pyogenes
Features - severe pain, central necrotic tissue, systemic illness
Managent - IVIG, surgical intervention

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12
Q

Meningococcal infection - features (3), prevention (1), risk of neuro damage compared to the other meningitis causing organisms

A

F - purpuric rash, necrotic centre
P - MenA, + Men C vaccine - Men B also available now
Long- term - lowest risk of neuro sequelae out of the 3 main causes of bacterial meningitis

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13
Q

Pneumococcal infection - why are young infants particularly at risk? what should be given to high risk infants?

A

Poor response in infants to encapsulated bacteria (the pneumococcal vaccine has reduced incidence of invasive disease)
Children at increased risk e.g. from hyposplenism should also be given daily prophylactic penicillin

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14
Q

Staph/GAS infections: impetigo; defintion, features (4), management (2)

A

D - localized highly contagious Staph or strep infection
(most common in young children where there is pre-existing skin disease e.g. atopic eczema)
F - lesions start as erythematous macules > become vesicular/ pustular > rupture of vesciles + exudation of fluid leads to characteristic confluent HONEY-COLOURED crusted lesions
M - Topical Abs e.g. Fucidic acid cream, narrow spec abs e.g. flucloxacillin,

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15
Q

Staph/GAS infections: Boils

A

infection of hair follicles/ sweat galnds, usually due to S. Aureus treat with ABs

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16
Q

Staph/GAS infections: Periorbital cellulitis - features (3), causes (2), management

A

D - fever + unilateral eyelid erythema + tenderness + oedema
C - other than strep/staph Hib, local trauma, dental abscess
M - IV abs

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17
Q

Staph/GAS infections: Scalded skin syndrome: defintion, features ( 5), management (2)

A

D - separation of epidermal skin through granular cell layers by exfloiative Staph toxin
F - tender flaccid bullae which rupture to show moist erythematous base, wide spread erythema + skin tenderness. Nikolsky sign - area of epidermis separates on gentle pressure
M - Flucloxacillin, analgesia, fluid balance

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18
Q

Staph/GAS infections: Scarlet fever: features ( 5), management (1), complications (3)

A

Caused by S. pyogenes
F - tonsilitis, fever, head sparing blanching punctate rash, furred tongue with enlarged papillae
M - Penicillin V/ Azithromycin
C - otitis media, post-strep GN, rheumatic fever

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19
Q

Human herpes viruses: HSV: type 1 & 2, treatment (1), ginivostomatitis - features (3), skin manifestations (2), eye disease (2), CNS infection (1)

A

HSV1 - oral/skin, HSV-2 genital
T - Acyclovir (viral DNA polymerase inhibitor)
Gingivostomatitis - most common primary HSV in children, vesicular lesions on lips, gums and tongue > progress to painful ulceration with bleeding + high fever. Child is miserable, resolves in 2 weeks. Treat symptomatically, acyclovir if requried
Eye disease - blepharitis (inflammation of eye lids) or conjunctivitis, can extend to involve cornea and lead to loss of vision
CNS - encephalitis

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20
Q

Human herpes viruses: VZV: avg incubation period (1), features (5), complications (4), management (3)

A

VZV is spread by resp droplets - highly infectious during viral shedding. Avg incubation period of 14 days.
F: start with fever, headache, malaise. 200-500 lesions appear on head & trunk, then progress to peripheries. Starts as papules > vesicles > pustules > crusts
Appear in crops for 3-5 days - if new rashes still forming after 10 days consider T cell defect
C - scar formation/ secondary infection if scratching, encephalitis, TSS, nec fasc. Also purpura fulminans (way more common with mengococcus) occurs due to vasculitis in skin + subcut tissue, due to production of anti-VZV abs which cross react with Protein S - inactivating it > dysregulation of fibrinolysis & increased risk of clotting
M - IV acyclovir, PO valaciclovir, VZIG if immunodeficient

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21
Q

Human herpes viruses: VZV - shingles; definition, features (2), recurrent shingles indicative of what?

A

D - reactivation of latent VZV (uncommon in children)
F - vesicular eruption in dermatomal distribution of sensory nerves - NOT associated with neuralgic pain
Recurrent/ multidermatomal shingles indicates T cell defect

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22
Q

Human herpes viruses: EBV: features (5)

A

EBV (also involved in pathogenesis of burkitt) has particular tropism for B cells and pharyngeal epithelial cells. Transmission is by oral contact, most infections subclinical. But sometimes can get a syndrome with:
F - fever, malaise, cervical lymphadenopathy, tonsillopharyngitis (usually quite severe - limiting oral ingestion), splenomegaly, hepatomegaly, petechiae in soft palate, maculopapular rash

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23
Q

Human herpes viruses: EBV diagnosis (3), management (2)

A

D - atypical lymphocytes on blood film, positive monospot test, anti-EBV IgM & IgG
M - symptomatic, steroids if airway obstruction due to tonsillopharyngitis (rare), dont give amoxicillin because can cause maculopapular rash (should resolve within 1-3 months)

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24
Q

Human herpes viruses: CMV; features (4), diagnosis (2), management (3)

A

CMV usually transmitted by saliva/ genital secretions/ breast milk. Causes mild/ subclin infections in normal hosts. Is imp in immunocompromised and fetus
F - retinitis, colitis, hepatitis, encephalitis, pneumonitis
D - atypical lymphocytes (owls eye inclusions), monospot negative
M - ganciclovir, Foscarnet, Cidofovir

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25
Q

Human herpes viruses: HHV 6/7 - Roseola Infantum; features (4)

A

F - high fever + malaise for few days > generalized macular rash appearing as fever wanes. May have febrile convulsion (commonest cause of febrile convulsions)

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26
Q

Human herpes viruses: HHV 8 - associated with what (1)

A

Kaposi sarcoma in HIV co-infected

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27
Q

Parvovirus B19: transmission (3), clinical syndromes (4)

A

Transmission - resp secretions from viraemic parents, vertical transmission mother to fetus, transfusion of contaminated blood products
B19 infects the erythroblastoid red cell precursors in BM & can cause range of clinical syndromes:
Asymp infection - common
Erythema infectiosum - most common; viraemic phase - fever, malaise, headache myalgia. Week later get ‘slapped cheek’ rash > progresses to maculopapular ‘lace’like rash on trunk & limbs
Aplastic crisis - most serious consequence occurs in haemolytic anaemias (increased RBC turnover) & immunocomprised
Fetal disease - fetal hydrops + death due to anaemia

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28
Q

Enteroviruses: generally cause (2), transmission (1)

A

They are mostly asymp/self-limiting
Usually cause fever and rash on trunk (blanching) + shin petechiae
Transmission is Faecal-oral

29
Q

Enteroviruses: HFMD (coxsackie A16 & enterovirus 71): features (2), management

A

Painful oral vesicles followed by palms/soles/ buttocks, mild systemic features
manage with fluids and analgesia

30
Q

Enteroviruses: Herpangina (Coxsackie) ; features (4) management

A

Vesicular ulcerated lesions on soft palate and uvula causing anorexia, dysphagia & fever
manage with fluids and analgesia

31
Q

Enteroviruses: meningitis/ encephalitis

A

aseptic meningitis, complete recovery expected

32
Q

Enteroviruses: Pleurodynia (bornholm disease) - features (3)

A

F - acute illness with fever, pleuritic chest pain & muscle tenderness. May hear pleural rub on examination - otherwise normal
Resolves within few days

33
Q

Measles: cause (1), Features (4), complications (4), prevention (1), management (2)

A

Morbilivirus
F - Koplik’s spots are pathognomic (white spots on buccal mucosa), coryza + fever + conjunctivitis, Rash - initially maculopapular and discrete > progress to blotchy + confluent
C - encephalitis, subacute sclerosing panencephalitis - rare but devastating; risk if

34
Q

Mumps: cause, features (5), diagnosis (1)

A

Mumps virus
F - starts with fever + malaise + parotitis. May get Orchitis, pancreatic involvement, meningitis/ encephalitis, ear ache
D - ELEVATED SERUM AMYLASE

35
Q

Rubella: cause, features (3), diagnosis (1), congenital infection ( 4)

A

Rubella virus
F - maculopapular (non-itchy) rash initally on face > spread to whole body fading in 3-5 days, suboccipital + post auricular lymphadenopathy
D - Rubella IgM
Congenital infection - cataracts, cardiac - PDA, ASD/VSD, retinopathy, microcephaly, deafness

36
Q

Prolonged fever: 4 infective causes & 4 non-infective

A

Infective - localized infection, deep abscess, IE, TB, bacterial e.g. typhoid
Non-infective - SLE, IBD, Sarcoid, Malignancy, vasculitis

37
Q

Kawasaki disease: definition, features (6)

A

D - systemic vasculitis affects 6months - 4yr olds; more common in Japanese & Afro-caribean
F - fever for > 5 days + 4/5 criteria: non purulent conjunctivitis, strawberry tongue/ cracked lips, palmar/ plantar erythema/desquamation, polymorphous exanthem, cervical LNpathy

38
Q

Kawasaki disease: Ix (4), management (2), complications (3)

A

Ix - clinical; WBC + ESR + CRP + platelets raised, Echo for coronary artery aneurysms
M - IVIG + high dose aspirin
C - Coronary artery aneurysms, gallop rhythm, myocarditis, sudden death

39
Q

TB: features (4)

A

mycobacteria that in most older children & half of infants is asymptomatic
F - in this case host IR fails to contain the bacilli, which spreads via LNS.
‘Ghon focus’ - lung lesion + LN
Fever, anorexia, weight loss
Hilar LNpathy. It can disseminate to bones, kidneys etc.

40
Q

TB: Ix (4)

A

CXR - ghon focus, lymphadeopathy, pleural effusion
Mantoux test - +ve if >10mm induration, or > 15mm induration (BCG given)
Sputum culture
Intereron gamma release assays (IGRA) - assess response of T cells to in vitro TB Ags (not found in BCGs - so a +ve result would indicate infection rather than vaccination)

41
Q

TB: management (1)

A

Rifampicin, Isoniazid, pyrazinamide, ethambutol (RIPE) for 2/12 > R & I for 4/12
if TB meningitis present give dexamethasone for 1 month

42
Q

Malaria: causes (4), features (4), diagnosis (2), management (2)

A

C - P. Falciparum , ovale, vivax, malariae
F - cyclical fever, D&V, flu-like symptoms, jaundice, anaemia, thrombocytopenia
D - thick blood film for identification of infection, thin for identification of organism
M - mild = quinine, severe - artemisinin-based combination therapy

43
Q

Typhoid: causes (2), features (4), management (2)

A

C - S. typhi/ paratyphi
F - D&V, headache, bradycardia, splenomegaly, rose spots
M - third generation cephalosporin / azithromycin

44
Q

Dengue: features (4), dengue haemorrhagic fever pathology (3)

A

F - fine erythematous rash, arthralgia, myalgia, high fever > secondary rash + desquamation
Dengue haemorrhagic fever - previously infected child has a subsequent infection with different viral strain > augmented infection severity > severe capillary leakage > hypotension + haemorrhagic manifestations
requires resusc

45
Q

Traveller’s diarrhoea (2 causes) and dysentery (4)

A

This is caused by change in gut flora, viruses e.g. rotavirus, E. Coli - treat with simple rehydration
Fever accompanied by loose stools with blood or mucus = dysentry - shigella, salmonella, Campylobacter, Entamoeba histolytica

46
Q

Viral haemorrhagic fever: causes (4)

A

Lassa, Ebola, Hanta virus, Crimean-Congo virus

47
Q

HIV: features (5), Ix (2), management (3)

A

F - lymphadenopathy, recurrent fever, hepatosplenomegaly, SPUR infections (serious, persistent, unusual, recurrent), parotid swelling, thrombocytopenia
Ix - if 18 months anti-HIV abs
M - HAART + co-trimoxazole, all routine vaccinations except BCG, MDT

48
Q

Methods to reduce HIV vertical transmission (4)

A

Use of maternal ante/peri/post natal ARV to maintain undetectable viral load
Avoidance of breast feeding
Active management of labour & delivery - no PROM or instrumentation
Csection if maternal viral load is detectable close to time of delivery

49
Q

Lyme disease: Cause (1), features early (4) late (4), diagnosis (1), Management (2)

A

Borrelia burgdorferi (from tick bite)
F - erythematous macule at site of tick bite > then develops classic painless red expanding lesion with bright red outer edge ERYTHEMA CHRONICUM MIGRANS. Early - myalgia, arthralgia, fever, malaise, LNpathy. Late - meningiencephalitis, crainl neuropathies (VII), myocarditis, heart block
Diagnosis - is clinical, & serology
M - Doxycyline if > 12 yr old, amoxicillin if

50
Q

T cell defects: presentation (3), SCID - mutation where

A

Severe or unsual viral & fungal infections + FTT in first months of life e.g. severe bronchiolitis, oral thrush, PCP
X-linked SCID - mutation in IL-2R chain on chromosome Xq13.1
Also HIV

51
Q

T cell defects: Wiskott-Aldrich triad

A

triad of thrombocytopenia + eczema + immune def (X-linked)

52
Q

T cell defects: DiGeorge - main immune defect, mutation

A

Maldevelopment of 5th branchial arch causing heart defects, facial defects, ABSENT THYMUS, hypocalcemia
Deleion of section on Cr 22

53
Q

T cell defects: Duncan syndrome (X-linked lymphoproliferative disease) main feature

A

Inability to respond to EBV - either succumb to infection or develop secondary lymphoma

54
Q

T cell defects: Ataxia telangectasia

A

Defect in DNA repair, also increased risk of lymphoma
cerebellar ataxia
developmental delay

55
Q

B cell defects presentation (2)

A

in 1st 2 yrs - severe bacterial inefctions, esp ear/sinus/pulmonary/ skin + FTT

56
Q

B cell defects: Bruton X-linked Agammaglobulinaemia

A

Abnormal Tyrosine Kinase gene > required for B cell maturation. Presents in 1st 6 months as infection with encapsulated organisms - affected growth

57
Q

B cell defects: Common variable immune def (CVID)

A

B cell def; low IgA/E/G, presents with recurrent bacterial infections

58
Q

B cell defects: Hyper IgM syndrome

A

B cells produce IgM but prevented from switching - CD40 ligand mutation

59
Q

B cell defects: selective IgA def

A

either asymp or recurrent ear/sinus/pulmonary infections

60
Q

Neutrophil defects: Presentation

A

REcurrent bacterial infections, abscesses, poor wound healing, invasive fungal infections e.g. aspergillosis, granulomas

61
Q

Neutrophil defects: Kostmann syndrome

A

Severe neutropenia - HAX-1 mutation

62
Q

Neutrophil defects: Chronic granulomatous disease

A

most X-linked recessive, defect in phagocytosis as fail to produce superoxide after ingestion of micro-organisms

63
Q

Neutrophil defects: Chediak-Higashi triad

A

Partial albimism + photophobia + nystagmus

64
Q

Leukocyte function defects: presentaiton

A

Delayed separation of umbilical cord, delayed wound healing, chronic skin infections and ulcers

65
Q

Leukocyte function defects: Leukocyte adhesion deficiency

A

Def of leukocyte surface adhesion molecules - CD18 & CD11b > inability of neutrophils to migrate to sites of infection/ inflammation

66
Q

Complement defects: presentation

A

Recurrent bacterial infections
SLE-like illness
Recurrent meningococcal infections

67
Q

Normal reaction following vaccination (3)

A

Swelling + discomfort at infection site +/- mild fever +/- mild form of disease

68
Q

Contraindications of Live vaccines

A

If child is IC

Has acute illness

69
Q

Contraindications for MMR vaccine

A

Neomycin allergy

anaphylaxis to egg