Ch 14 - Infection & immunity Flashcards Preview

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Flashcards in Ch 14 - Infection & immunity Deck (69):

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

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


Bacterial meningitis: features (8)

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
Neck stiffness
Kernig/ Brudzinski sign +ve


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

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


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

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


Management of Meningitis (bacterial) (2)

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


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

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


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

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


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

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


TSS: management (3)

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


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

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


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

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


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

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


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

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


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

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,


Staph/GAS infections: Boils

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


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

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


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

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


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

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


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

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


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

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


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

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


Human herpes viruses: EBV: features (5)

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


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

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)


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

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


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

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


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

Kaposi sarcoma in HIV co-infected


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

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


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

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


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

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


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

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


Enteroviruses: meningitis/ encephalitis

aseptic meningitis, complete recovery expected


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

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


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

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


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

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


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

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


Prolonged fever: 4 infective causes & 4 non-infective

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


Kawasaki disease: definition, features (6)

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


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

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


TB: features (4)

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.


TB: Ix (4)

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)


TB: management (1)

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


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

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


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

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


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

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


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

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


Viral haemorrhagic fever: causes (4)

Lassa, Ebola, Hanta virus, Crimean-Congo virus


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

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


Methods to reduce HIV vertical transmission (4)

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


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

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


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

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


T cell defects: Wiskott-Aldrich triad

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


T cell defects: DiGeorge - main immune defect, mutation

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


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

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


T cell defects: Ataxia telangectasia

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


B cell defects presentation (2)

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


B cell defects: Bruton X-linked Agammaglobulinaemia

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


B cell defects: Common variable immune def (CVID)

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


B cell defects: Hyper IgM syndrome

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


B cell defects: selective IgA def

either asymp or recurrent ear/sinus/pulmonary infections


Neutrophil defects: Presentation

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


Neutrophil defects: Kostmann syndrome

Severe neutropenia - HAX-1 mutation


Neutrophil defects: Chronic granulomatous disease

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


Neutrophil defects: Chediak-Higashi triad

Partial albimism + photophobia + nystagmus


Leukocyte function defects: presentaiton

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


Leukocyte function defects: Leukocyte adhesion deficiency

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


Complement defects: presentation

Recurrent bacterial infections
SLE-like illness
Recurrent meningococcal infections


Normal reaction following vaccination (3)

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


Contraindications of Live vaccines

If child is IC
Has acute illness


Contraindications for MMR vaccine

Neomycin allergy
anaphylaxis to egg