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Infection And Immunity Notes

Medicine Notes > Paediatrics Notes

This is an extract of our Infection And Immunity document, which we sell as part of our Paediatrics Notes collection written by the top tier of University Of Nottingham students.

The following is a more accessble plain text extract of the PDF sample above, taken from our Paediatrics Notes. Due to the challenges of extracting text from PDFs, it will have odd formatting:

Infection and Immunity Maybe look at the pictures of various rashes The Febrile Child See NICE guidance

*

Most have brief, self limiting viral infections or mild localised infections (otitis media, tonsillitis)

*

Clinical Features

o

Risk factors for infectionIllness of family membersIllness in the communityUnimmunisedRecent travel abroad (malaria, typhoid)Contact with animalsImmunodeficiencySickle cell disease, splenectomy, nephrotic syndrome increased susceptibility to

encapsulated organisms (Strep. pneumoniae, Hib, salmonella)

o

How if fever identified?In hospital it is measure at:

*

<4 weeks old - electic thermometer in the axilla

*

4 weeks - 5 years electric or chemical dot thermometer in the axilla or

infrared tympanic thermometer

*
o

Axillary temperature is 0.5oC less than body temperature

How old is the child?Febrile infants <3 months present with non specific clinical features (SEE neonatal

infection notes)*

Often have bacterial infection

*

Viral infections are uncommon due to massive maternal immunity

*

Should have vital signs measured and recorded

o

Temp

o

HR

o

RR

If no source is obvious require urgent investigation with septic screen and IV antibiotics

*

FBC, Blood culture

*

WCC

*

Acute phase reactant (CRP)

*

Urine

*

Consider (if red flags)

o

CXR,

o

Lumbar puncture,

o

Stool culture,

o

Serum electrolytes

o

Blood gas

o

Meningococcal and pneumococcal PCR on blood/CSF, PCR for viruses in CSF (HSV, enterovirus)o

Start parenteral antibiotics if:

*

<1 month old

*

13 months and unwell

*

13 months with altered WCC

How ill is the child?Measure

*

Temp

*

o

Fever >38 if <3 months

o

Fever >39 if 36 months

HR

*o

If raised can indicate SHOCK

*

RR

*

Cap refill

Assess for signs of dehydration

*

Prolonged cap refill

*

Abnormal skin turgor

*

Abnormal resp rate

*

Weak pulse

Is there a focus for infection?following:

When there is no apparent cause of infection the differential should include the

Diagnosis Meningococcal Disease

Meningitis

Symptoms and Signs Non blanching rash with one or more of:

*

Ill looking child

*

Lesions larger than 2mm (purpura)

*

CRT >3s

* Neck stiffness Neck stiffness Bulging fontanelle Decreased consciousness Convulsive status epilepticus

HSV Encephalitis

(Classic signs are often absent in infants) Focal neurology Focal seizures

Pneumonia

Decreased consciousness Tachypnoea

*

Neonate >60

*

Infant >50

*

Young child >40

Crackles Nasal flaring Chest indrawing Cyanosis UTI

Oxygen sats <95%
Vomiting Poor feeding Lethargy Irritability Abdominal pain Frequency / dysuria

Septic Arthritis / Osteomyelitis

Offensive urine / haematuria Swelling of a limb or joint Not using an extremity

Kawasaki Disease

Nonweight bearing Fever lasting longer than 5 days plus four of:

*

Bilateral conjunctival injection

*

Change in upper resp tract mucosa

*

Change

in

periphera

extremities

desquamation)

*

Polymorphous rash

*

Cervical lymphadenopathy

(oedema,

erythema,

Traffic Light System to Identify Serious Illness Colour

Green Normal

Amber Pallor

Red Pale, mottled, ashen or

Activity

Responds normally

Not responding normally

blue Unresponsive

Content, smiles

Decreased activity

Barely rousable

Prolonged

Weak,

Stays awake Awakens

quickly

when

stimulation

high

pitched

required to awaken

continuous cry

Nasal flaring

Grunting

Tachypnoea

Severe distress

roused Strong normal cry Normal

Breathing

Desaturation (<95%) in air Hydration

Normal

Chest crackles Dry mucous membranes

Reduced skin turgor

Poor feeding Reduced urine output Other

Generally normal

Capillary refill >3s Fever >5 days

Non blanching rash

No fever

Swelling of limb/joint

Fever at time of exam

New lump >2cm

Bulging fontanelle Neck stiffness Seizures Focal neurology Bile stained vomit

*

Management

o

o

o

o

Children with only green features and no definite diagnosis can be managed at homePerform UTI, assess for symptoms and signs of pneumoniaDo not perform routine blood tests or XR

Amber features and no diagnosisUrine test, FBC, Blood culture, CRP routinePerform CXR IF fever >39 and WCC raisedConsider lumber puncture if <1 year old

Any Red features and no diagnosisBlood culture, FBC, urine test, CRPLumbar puncture, CXR, electrolytes and blood gas as clinically deemed necessary

Parenteral antibiotics are given immediately to seriously unwell childrenThird generation cephalosporin (cefotazime, ceftriaxone) if >3 months old

or

?o

In infants;

*

Cefotaxime in septicaemia or meningitis

*

Ampicillin in listeria / Gp B strep

Aciclovir in HSV encephalitis

Antipyretics paracetemol or ibuprofenDo NOT use damp spongeDo NOT over or underdress the child

Septicaemia

*

Bacteria may cause a focal infection or proliferate in the blood stream leading to septicaemia

*

In septicaemia the host response involves release of cytokines and activation of endothelial cells leading to septic shock

*

Commonest cause is meningococcal infection (+/ meningitis)

o

Incidence has reduced due to immunisation

*

Pneumococcus is the commonest organism causing bacteraemia (not typically septic shock)

*

In neonates are group B strep or gram negative organisms

*

Clinical spectrum produced by 4 elements:

o

Capillary leakFrom presentation until day 24 vascular permeability massively increasesProtein enters intravascular space and urine causing severe hypovolaemiaInitial vasoconstriction to compensate but eventually decreased venous return and decreased cardiac output

o

CoagulopathySevere bleed tendency in meningococcaemiaPresents with severe thrombosis in microvasculature of the skin, often in a glove and stocking distribution, sometimes requiring amputation

o

Metabolic derangementProfound acidosis occurs with severe metabolic abnormalities including hypokalaemia, hypocalcaemia, hypomagnesaemia and hypophosphataemia

o

Myocardial failureFunction remains impaired even after t circulating volume is restored and metabolic abnormalities correctedGallop rhythm often audibleElevated CVP and hepatomegaly

?

Thought to result from direct damage with proinflammatory mediators, acidosis and hypoxia

*

Clinical Features

o

Fever

o

Poor feeding

o

Miserable, irritable, lethargy

o

History of focal infecition

o

Predisposing conditions

o

Tachycardia

o

Tachypnoea

o

Low BP

o

Purpuric rash (meningococcal septicaemia)

o

Shock

Age Neonate Infant Young Child Older Child

Normal 3050 2030 2030 1520

Age
<1 yr 25 years 5-12 years
>12 years

*

Tachypnoea
>60
>50
>40
>30

Beats/min 110160 95140 80120 60100

Management

o

Antibiotics

o

Fluids due to loss of plasma volume, may lead to pulmonary oedema

o

Circulatory support inotropic support due to poor myocardial contractility

o

DIC fresh frozen plasma and platelets

Shock

*

Cicrulation is inadequate to meet the demands of the tissues

*

Children require much higher fluid intake per kg than adults

o

*

Due to higher surface area to volume ratio and higher BMR

Clinical Features

o

Early

o

*TachynpnoeTachycardiaDecreased skin turgorSunken eyes and fontanelleDelayed capillary refillMottled pale, cold skinDecreased urine output

Late (decompensated0Acidotic (Kussmaul) breathingConfusionBlue peripheriesAnuriaHypotension

Management

o

Fluid resuscitation!!! (20ml/kg)

o

Oxygen if sats. <92%

Meningitis

*

Inflammation of the meninges

*

Inflammatory cells found in the CSF

*

Viral infections are the most common cause and are self resolving

*

Bacterial meningitis is severe

Bacterial Meningitis

*

80% are younger than 16

*

510% mortality

*

10% have long term neurological impairment

*

Peak incidence 624 months

*

Most cases under 4 yearrs

*

Pathogenesis

o

Colonisation and invasion of nasopharyngeal epithelium

o

Invasion of blood stream

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