Infectious Disease Flashcards
What is the septic screen in children?
Blood vulture
FBC including WCC
Acute phase reactant
Urine sample
Consider a CXR
Lumbar puncture (unless contraindicated)
Rapid antigen screen on blood/ CSF/ urine
Meningococcal and pneumococcal PCR on blood/CSF samples
PCR for viruses in CSF(HSV and enteroviruses)
What risk factors for infection do you want to ask about in
Illness of other family members Specific illness prevalent in commuNity Lack of immunisations Recent travel abroad Contact with animals Immunodeficiency
What are red flag features you should consider when a child is ill/has a fever?
Fever over 38 degrees if they are less than 3 months, or over 39 degrees if they are 3 months to 6 months of age.
Colour- if they are pale, mottled or cyanosed
Level of consciousness being reduced, neck stiffness, bulging fontanelle, status epilepticus, focal neurological signs or seizures
Significant resp distress
Bile stained vomiting
Severe dehydration or shock
What would the classic rash be for meningitis?
Non blanching purpuric rash
When looking at the febrile child, how can you find the focus of the infection?
Do a head to toe approach
Check fontanelles- meningitis/encephalitis?
Look at ENT sources- peri orbital cellulitis, otitis
Media, tonsillitis, upper respiratory tract infection
Look for any rashes on the chest and listen to the chest for pneumonia
Do a urine dip for A UTI
Look for signs of septicaemia (tachycardia, tachypnoea, poor perfusion, need to start ABx in clinical suspicion without waiting for culture results).
Look for abdominal pain/tenderness (appendicitis/pyelonephritis/hepatitis), look at joints for osteomyelitis or septic arthritis
Is there any diarrhoea (gastroenteritis, or if there is fever with blood and mucus in the stool- shigella, salmonella, campylobacter).
How should you treat seriously unwell children with a fever?
Parenteral antibiotics should be given immediately to seriously unwell children eg: a third generation cephalosporin such as: cefotaxime (<1 month old who have been discharged from hospital) or ceftriaxone (>1 month old)
Remember that in children under 1 month ampicillin is also added to cover for listeria infection.
What treatment is given if herpes simplex encephalitis is suspected?
Aciclovir
What are the early (compensated) signs of shock?
Tachypnoea Tachycardia Reduced skin turgor Sunken eyes and fontanelle Delayed cap refill (>2seconds) Pale, cold, mottled Temperature gap (>4degrees) Decreased urinary output
What are the late (decompensated) signs of shock?
Acidotic (kussmaul) breathing- this is deep and laboured Bradycardia Confusion/depressed cerebral state Blue peripheries Absent urine output Hypotension
How do you rescucitate a child in shock?
Initially you would give 0.9% saline or blood (20ml/kg) and you can give that two times if necessary, if there is no improvement then you take them to intensive care, if there is improvement then you correct the hypovolaemia.
How do you calculate the maintenance IV fluid requirements in children?
First 10kg= 100mls
Second 10kg= 50mls
Subsequent kg = 20mls
What should you do if there is no improvement following the initial fluid resuscitation or if there is progression of shock and Resp failure?
Paediatric intensive care unit should be involved and transfer arranged, the child may need:
Tracheal intubation and mechanical ventilation
Invasive monitoring of blood pressure
Inotropic support
Correction of haematological, biochemical and metabolic derangements
Support for renal failure
What is shock?
Insufficient blood flow to the tissues of the body as a result of problems with the circulatory system
What are the four types of shock?
Low volume
Cardiogenic
Obstructive
Distributive shock (sepsis)
What is sepsis?
Sepsis is the overwhelming and life threateninf response to an indection leading to poor perfusion to the tissues/organs.
What are the clinical features of septicaemia in terms of history and examination?
History- fever, focal infection, poor feeding, miserable, irritable, lethargic, predisposinf immunodeficiency (like sickle cell disease)
Examination- fever, tachycardia, tachypnoea, low BP, purpuric rash, shock, multiorgan failure
What are the management options of shock?
Children with septic shock like having organ failure may need to be transferred to PICU.
Antibiotic therapy must be started without delay, the choice should be based on the childs age and any predisposition to infection
Fluids- Central venous pressure monitoring and urinary catheterisation may be required to guide fluid balance assessment.
Inotropic support may be needed as inflammatory cytokines and circulating toxins may depress myocardial contractility
Disseminated intravascular coagulation
Abnormal blood clotting in sepsis leads to widespread microvascular thrombosis and consumption of clotting factors. If bleeding occurs then clotting derangement should be corrected with fresh frozen plasma, cryoprecipitate and platelet transfusions.
What are the signs and symptoms of candidiasis?
Wide range of symptoms
1) candidiasis of the skin- commonly occur in folds of the skin, lesions are usually rimmed with small, red based pustules
2) vulvovaginitis or vaginitis caused by candida
3) penis infected by candida
4) oral candidiasis (thrush)
Candida around nails, systemic candidas
What may discharge and a red eye be due to?
This may be due to a staphylococcal or streptococcal infection
How would you treat staphylococcal or streptococcal infections of the eye?
Can be treated with a topical antibiotic eye ointment- chloramphenicol or neomycin.
What may purulent discharge with conjunctival infection and swelling of the eyelids within the first 48 hours be due to?
Gonococcal infection
The discharge should be gram stained urgently, as well as cultured and treatment should be started immediately due to the loss of vision that can occur.
If gonococcal eye infection is present, how do you treat?
Due to penicillin resistance you would use a third generation cephalosporin given IV with frequent eye cleaning.
Chlamydia trachomatis can cause an eye infection, how does this usually present?
Usually presents with a purulent discharge, together with swelling of the eyelids at 1-2 weeks of age, but may also present shortly after birth.
The organism dan be identified with immunofluorescent staining
How do you treat chlamydia trachomatis eye infection?
Oral erythromycin for 2 weeks
Mother and partner also need to be checked and treated
What is the presentation of herpes simplex virus?
Presentation is any time up to 4 weeks of age
Localised herpetic lesions on the skin or eye, or with encephalitis or disseminated disease.
How can you treat HSV?
Aciclovir
If the woman has genital herpetic lesions at the time of delivery then an elective C section is indicated
If the woman has recurrent infections then vaginal delivery can be carried out as normaL.
What can H influenzae cause?
Important cause of systemic illness in children, including otitis media, pneumonia, epiglottitis, cellulitis, osteomyelitis and septic arthritis, was the second most common cause of meningitis in the UK. Immunizisation is highly effective and Hib now rarely causes systemic disease.
What is the presentation of periorbital cellulitis?
Erythema, tenderness, oedema of the eyelid or other skin adjacent to the eye
It is almost always unilateral
How do you get periorbital cellulitis?
It may follow local trauma to the skin.
In older children it may spread from a paranasal sinus infection or dental abscess
How do you treat periorbital cellulitis?
Should be treated promptly with IV abx such as high dose ceftriaxone to prevent posterior spread of the infection and causing orbital cellulitis
How would orbital cellulitis present?
Proptosis
Painful or limited ocular movement with or without reduced visual acuity
Orbital cellulitis may be complicated, what is it complicated with?
Abscess formation
Meningitis
Cavernous sinus thrombosis
What should be done if orbital cellulitis is suspected?
CT/MRI scan should be performed to assess the posterior spread of infection.
How does HSV enter the body?
HSV enters the body through the mucous membranes or skin and the primary infection may be associated with intense local mucosal damage.
There are eight known herpes viruses, what is HHV-8 associated with?
Kaposi sarcoma in HIV infected individuals.
What is the difference between HSV-1 and HSV-2 viruses?
HSV-1 is usually associated with lip and skin lesions
HSV-2 more commonly associated with genital lesions but both can cause both types
What is the most common form of primary HSV illness in children?
Gingivostomatitis
It usually occurs from ten months to 3 years of age
How does gingivostomatitis present?
Vesicular lesions on the lips, gums, anterior surfaces of the tongue and hard palate which often progress to extensive, painful ulceration with bleeding. There is high fever and the child is very miserable.
Dehydration may occur due to pain of eating and drinking
What is the treatment of gingivostomatitis?
Management is symptomatic but severe disease may need IV fluids and aciclovir.
Other than gingivostomatitis, what can herpes simplex virus cause?
Skin manifestations- mucocutaneous junctions eg: lips and damaged skin
Eczema herpeticum
Herpetic whitlows (painful pustules on the fingers)
Eye disease- blepharitis, conjunctivitis, corneal ulceration
CNS- aseptic meningitis, encephalitis
Pneumonia and disseminated infection in the immunocompromised
What is the pathophysiology of bacterial infection?
Bacterial infection of the meninges usually follows bacteraemia. Much of the damage caused by meningeal infection results from the host response to infection and not from the organism itself
The release of inflammatory mediators, activated leucocytes together with endothelial damage leads to cerebral oedema, raised ICP and decreased cerebral blood flow
The inflammatory response below the meninges causes a vasculopathy which results in cerebral cortical infarction, and fibrin deposits may block the resorption of CSF by the arachnoid villi which results in hydrocephalus.
What are the organisms that cause bacterial meningitis?
Neonatal to 3 months= group B streptococcus
E coli
1 month to 6 years: neisseria meningitides, strep pneumoniae, haemophilus influenza
> 6 years strep pneumonia, neisseria meningitides
What are the investigations for meningitis/encephalitis?
FBC and differential count
Blood glucose and blood gas (for acidosis)
Coagulation screen, CRP, U&Es, LFTs
Culture of blood, throat swab, urine, stool for bacteria
Rapid antigen test can be done on blood, CSF or urine
Samples for viral PCRS
Lumbar puncture for CSF unless contraindicated
If TB suspected then CXR, mantoux, and/or onterferon gamma release assay, gastric aspirates or sputum for microscopy and culture
What are the contraindications to lumbar punctures
Cerebal oedema cardiorespiratory instability Focal neurological signs Thrombocytopenia Local infection at the site of LP If it causes delay in starting antibiotics
It can cause coning of the cerebellum through the foramen magnum in these circumstances.
What are the cerebral complications of bacterial meningitis?
Hearing impairment Local vasculitis Local cerebral infarction Subdural effusion Hydrocephalus Cerebral abscess
What causes viral meningitis?
Enteroviruses
EBV
Adenoviruses
Mumps (rare due to the MMR)
What are the clinical features of mumps?
Incubation period is 15 to 24 days
Onset of the illness is with fever, malaise and parotitis
Only one side of the face may be swollen initially, but bilateral parotid involvement nay occur over the next few days. Parotitis is uncomfortable and children may complain of earache or pain on eating or drinking.
What is a common fear of mumps?
Orchitis
When it occurs its unilateral
What is malaria?
Infectious disease caused by members of the plasmodium family of protozoan parasites.
What is the most severe and dangerous plasmodium member family?
Plasmodium falciparum
How is malaria spread?
Spread through bites from the female anopheles mosquitos
How does malaria lead to haemolytic anaemia?
Sporozoites mature in the liver into merozoites which enter the blood and infect red blood cells. In red blood cells, the merozoites reproduce 48 hours after which the red blood cells rupture releasing loads more merozoites into the blood and causing a haemolytic anaemia.
This is why people with malaria have high fever spikes every 48 hours.
What are the non specific symptoms and signs of malaria?
Non specific symptoms: . Fever, sweats, rigors . Malaise . Myalgia . Headache . Vomiting
Signs:
. Pallor due to anaemia
. Hepatosplenomegaly
. Jaundice as bilirubin is released during the rupture of red blood cells
How do you diagnose malaria?
Malaria blood film which is sent in an EDTA bottle, the red top bottle used for a FBC
The malaria blood film will show parasites, the concentration and what type they are
3 samples are sent over 3 consecutive days to exclude malaria being released into the blood from red blood cells
The sample may be negative on days where the parasite is not released but becomes positive a day or two later when they are released from the RBCS
What is the management of malaria?
Oral options in uncomplicated:
Quinine sulphate
Doxycycline
IV options in severe or complicated
Artesunate
Quinine dihydrochloride
What are the falciparum complications?
Cerebral malaria Seizures Reduced consciousness AKI Pulmonary oedema DIC Severe haemolytic anaemia Multi organ failure and death
