Infectious Disease Flashcards
What is an inactivated vaccine ?
Involves giving a killed version of the pathogen. They cannot cause an infection and are safe for immunocompromised patients although they may not have an adequate response.
Examples - polio, flu vaccine, hepatitis A and rabies
What is a subunit and conjugate vaccine ?
Only contains parts of the organism used to stimulate an immune response. They also cannot cause infection and are safe for immunocompromised patients. For example : pneumococcus, meningococcus, hepatitis B, pertussis, Haemophilus influenza type b, HPV and shingles
What is a live attenuated vaccines ?
A weakened version of the pathogen. They are still capable of causing infection particularly in immunocompromised patients. For example :
Measles, mumps and rubella
BCG
Chicken pox
Nasal influenza
Rotavirus
What is a toxin vaccine ?
A toxin that is normally produced by a pathogen. They cause immunity to the toxin and not the pathogen itself. For example :
Diphtheria
Tetanus
What vaccines are given at the 8 week mark ?
6 in 1 vaccine - diphtheria, tetanus, pertussis, polio, haemophilus, type B (hiB) and hepatitis B
Meningococcal type B
Rotavirus
What is vaccine are given at the 16 week mark ?
6 in 1 vaccine
Meningococcal
What vaccines is given at the 12 week mark ?
6 in 1
Pneumococcal
Rotavirus
What vaccines are included in the 6 in 1 ?
Diphtheria
Tetanus
Pertussis
Polio
Haemophilus influenza
Type B (HiB)
Hepatitis B
What vaccines are given at the 1 year mark ?
2 in 1 - Haemophilus type B and meningococcal type c
Pneumococcal
MMR
Meningococcal type b
At what age is the influenza vaccine given ( nasal vaccine ) ?
2 - 8 years old
At what age is the HPV vaccine given ?
12-13 years old
What strains of HPV cause genital warts ?
6 and 11
What strains of HPV cause cervical cancer ?
16 and 18
How does inflammation throughout the body occur in sepsis ?
The causative pathogens are recognised by macrophages, lymphocytes and mast cells. These cells release vast amounts of cytokines such as interleukins and tumour necrosis factor to alert the immune system. This immune activation leads to further release of chemicals such as nitrous oxide that causes vasodilation. This causes inflammation.
How does sepsis cause oedema ?
Many of these cytokines cause the endothelial lining of blood vessels to become more permeable. This causes fluid to leak out of the blood into the extracellular space, leading to oedema and a reduction in intravascular space.
How does sepsis cause DIC ?
Activation of the coagulation system leads to deposition of fibrin throughout the circulation further compromising organ and tissue perfusion.
It also leads to consumption of platelets and clotting factors. This leads to thrombocytopenia, haemorrhages and an inability to form clots and stop bleeding. This is called disseminated intravascular coagulopathy.
Why is the lactate levels high in sepsis ?
Blood lactate rises as a result of anaerobic respiration in the hypo-perfused tissues with an inadequate oxygen. A waste product of anaerobic respiration is lactate.
What is septic shock ?
It is diagnosed when sepsis has lead to cardiovascular dysfunction. The arterial blood pressure falls, resulting in organ hypo-perfusion. Anaerobic respiration starts.
What is the management of septic shock ?
Treated aggressively with IV fluids to improve the blood pressure and tissue perfusion.
If this fails then a child should be escalated to high dependency or intensive care where inotropes can be given ( noradrenalin ).
What are the signs of sepsis in children ?
Deranged physical observations
Prolonged CRT
Fever or hypothermia
Deranged behaviour
Poor feeding
High pitched crying
Reduced consciousness
Reduced body tone
Skin colour changes
Shock - circulatory collapse
What is the immediate management of sepsis ?
Give oxygen if evidence of shock or oxygen sats below 94%
Obtain IV access
Blood tests - FBC, U&E’s, CRP, clotting screen, blood gas
Blood cultures
Urine dipstick
Antibiotics within an hour of presentation
IV fluids
What are some additional investigations to be performed depending on suspected infection for sepsis ?
CXR
Abdominal and pelvic USS
Lumbar puncture
Meningococcal PCR
Serum cortisol if adrenal crisis
What is meningitis ?
Defined as inflammation of the meninges.
Usually due to a bacterial or viral infection
How does neisseria meningitidis present on a gram stain ?
Gram negative diplococcus
What does a rash in meningitis suggest ?
It causes the non-blanching rash.
Caused by the infection causing DIC and subcutaneous haemorrhages.
What is bacterial meningitis ?
Inflammation of the meninges caused by a bacterial infection.
Most common cause - neisseria meningitidis and streptococcus pneumoniae.
What is the most common cause of bacterial meningitis in neonates ?
Group B strep ( GBS )
How does meningitis present ?
Fever
Neck stiffness
Vomiting
Headache
Photophobia
Altered consciousness
Non-blanching rash
Seizures
How do neonates present with sepsis ?
Hypotonia
Poor feeding
Lethargy
Hypothermia
Bulging fontanelle
What are 2 special tests you can perform to look for meningeal irritation ?
Kernig’s test
Brudzinski’s test
How do you perform Kernig’s test ?
Involves lying the patient on their back, flexing one hip and knee to 90 degrees and then slowly straightening the knee whilst keeping the hip flexed at 90 degrees.
This creates a slight stretch in the meninges.
In meningitis - Spinal pain or resistance to movement
What is Brudzinski’s test ?
Involves lying the patient flat on their back and gently using your hands to lift their head and neck off the bed and flex their chin to their chest.
In a Positive test the patient involuntarily flexes their hips and knees.
How should meningitis presenting in the GP be managed ?
Urgent stat injection ( IM or IV ) of benzylpenicillin prior to transfer to hospital.
Giving antibiotics should not delay transfer to the hospital.
How should meningitis be diagnosed ?
Lumbar puncture
Meningococcal PCR - quicker than a blood culture
How is meningitis treated ?
Under 3 months - cefotaxime plus amoxicillin
Above 3 months - cetriaxone
Dexamethasone also is used in bacterial meningitis
What is the usual choice of antibiotics in post exposure prophylaxis of meningitis ?
Single dose of ciprofloxacin
What are the most common causes of viral meningitis ?
Herpes simplex virus
Enterovirus
Varicella zoster virus
How is viral meningitis diagnosed ?
A sample of CSF from the lumbar puncture should be sent for viral PCR testing.
how is viral meningitis treated ?
Aciclovir can be used to treat suspected or confirmed HSV or VZV infection
How is a lumbar puncture performed ?
Involves inserting a needle into the lower back to collect a sample of CSF.
The needle is inserted into the L3-L4 space.
After performing a lumbar puncture what investigations should be performed when suspecting meningitis ?
Bacterial culture
Viral PCR
Cell count
Protein
Glucose
How does bacterial meningitis appear from a sample of cerebrospinal fluid ?
Appearance - cloudy
Protein - high
Glucose - low
WCC - high ( neutrophils )
Culture - bacteria
how does viral meningitis appear from a sample of CSF ?
Appearance - clear
Protein - mildly raised or normal
Glucose - normal
WCC - high ( lymphocytes )
Culture - negative
What are some complications of meningitis ?
Hearing loss
Seizures and epilepsy
Cognitive impairment and learning disability
Memory loss
Cerebral palsy
What is encephalitis ?
Inflammation of the brain which can be infective or non-infective ( autoimmune ).
What is the most common cause of encephalitis in children ?
Viral - herpes simplex virus 1 from cold sores
What is the most common cause of encephalitis in neonates ?
Herpes simplex type 2 from genital herpes contracted during birth
What are some other viral causes for encephalitis rather than the main one ?
Varicella zoster virus
Cytomegalovirus
Epstein Barr virus
How does encephalitis present ?
Altered consciousness
Altered cognition
Unusual behaviour
Acute onset of focal neurological symptoms
Acute onset of focal seizures
Fever
How is encephalitis diagnosed ?
LP sending CSF for viral PCR
CT scan
MRI scan
EEG recording
Swabs - throat and vesicle
HIV testing
What are some contraindications for having an LP ?
A GCS below 9
Haemodynamically unstable
Active seizures or post ictal
What is the management of encephalitis ?
IV antivirals :
- aciclovir for HSV or VZV
- ganciclovir for cytomegalovirus
What are some complications of encephalitis ?
Lasting fatigue and prolonged recovery
Change in personality or mood
Changes in memory and cognition
Learning disability
Headaches
Chronic pain
Movement disorders
Sensory disturbance
Seizures
Hormonal imbalance
What is infectious mononucleosis ?
A condition caused by infection with the Epstein Barr virus.
Commonly known as kissing disease or glandular fever
The virus is found in the saliva.
What are some features of infectious mononucleosis ?
Fever
Sore throat
Fatigue
Lymphadenopathy
Tonsillar enlargement
Splenomegaly ( rare cases - splenic rupture )
What are heterophile antibodies ?
In infectious mononucleosis the body produces heterophile antibodies which are antibodies that are more multipurpose and not specific to the EBV virus.
It takes up to 6 weeks to produce.
What are 2 tests that test for heterophile antibodies ?
Mono spot test
Paul-bunnell test
What is the management of infectious mononucleosis ?
Usually self - limiting
Illness lasts 2-3 weeks
Advise to avoid alcohol and contact sport
What are some complication of infectious mononucleosis ?
Splenic rupture
Glomerulonephritis
Haemolytic anaemia
Thrombocytopenia
Chronic fatigue
Certain cancers - Burkitt’s lymphoma
What is mumps ?
A viral infection spread by respiratory droplets.
Incubation period - 14 to 25 days
How does mumps present ?
Initial period of flu-like symptoms known as the prodrome.
Parotid swelling
Fever
Muscle aches
Lethargy
Reduced appetite
Headache
Dry mouth
What is the management of mumps ?
Supportive - rest, fluids and analgesia
Self limiting condition
How is mumps diagnosed ?
PCR testing on a saliva swab - antibodies
What is HIV ?
Refers to the human immunodeficiency virus that causes the infection that makes someone HIV positive.
What is AIDS ?
Refers to the acquired immunodeficiency syndrome that occurs at the end stages of HIV infection, once the infection has affected the immune system enough to make the person susceptible to recurrent and unusual infections.
What is the pathophysiology of HIV ?
An RNA retrovirus
The virus enters and destroys the CD4 T helper cells.
An initial flu like illness occurs within a few weeks of infection
The infection is then asymptomatic until a person becomes immunocompromised.
How is HIV transmitted ?
Unprotected anal, vaginal or oral sexual activity
Mother to child during pregnancy, birth or breastfeeding.
Mucous membrane, blood or open wound exposure to infected blood or bodily fluids.
What are the 2 options that exist for testing for HIV ?
HIV antibody screen
HIV viral load
When should you test for HIV in children ?
Babies to HIV positive
When immunodeficiency is suspected
Young people who are sexually active
Risk factors - needle stick injuries, sexual abuse or iV drug use
What is the management of HIV ?
Antiretrovirus therapy
Normal childhood vaccines
Prophylactic co-trimoxazole - protect against pneumocystitis jiroveci pneumonia
Treat opportunistic infections
What is the aim of antiretroviral therapy ?
To achieve a normal CD4 count and undetectable viral load.
What teams should be involved in paediatric HIV ?
Regular follow up to monitor growth and development
Dietician input for nutritional support
Parental education about the condition
Psychological support
Specific sex education in relation to HIV when appropriate
What is hepatitis b and how is it spread ?
A DNA virus transmitted by direct contact with blood or bodily fluids. It can be passed through shared contaminated household products such as toothbrush or contact between minor cuts. Can be vertical transmission.
What are some rare complications of chronic hepatitis B ?
Liver cirrhosis
Hepatocellular carcinoma
What does surface antigen ( HBsAg ) suggest about the HIV infection ?
Active infection
What does E antigen ( HBeAg ) suggest about the HIV infection ?
Marker of viral replication and implies high infectivity
What does core antibody ( HBcAb ) suggest about the HIV infection ?
Implies past or current infection
What does surface antibody ( HBsAb ) suggest about the HIV infection ?
Implies vaccination or past or current infection
What is given to babies to reduce the risk of contracting hepatitis B at birth when the mother is hepatitis B positive ?
Hepatitis B vaccine
Hepatitis B immunoglobulin infusion
What is the management of hepatitis B ?
Most children do not require treatment and are asymptomatic.
If there is evidence of hepatitis or cirrhosis treatment with antiviral medications may be considered.
What does the hepatitis B vaccine involve ?
Hepatitis B surface antigen
What is hepatitis C and how is it spread ?
RNA virus - spread by blood or bodily fluids
What are some complications of hepatitis C ?
Liver cirrhosis and associated complications
Hepatocellular carcinoma
How is hepatitis C tested for ?
Hepatitis C antibody - screening
Hepatitis C RNA - confirm the diagnosis of hepatitis C, calculate the viral load and identify the genotype.
What is the management of hepatitis C ?
Treatment in children involves pegylated interferon and ribavirin.
Typically delayed until adulthood.
How should a baby to a hepatitis C positive mother be tested and managed ?
Tested at 18 months of age using the hepatitis C antibody test
Breastfeeding has not been found to spread hepatitis C
If nipples become cracked or bleed breastfeeding should be stopped.
What is tonsillitis ?
Refers to inflammation in the tonsils.
What is the most common cause of tonsillitis ?
Viral infection
What is the most common bacterial cause of tonsillitis ?
Group A streptococcus - strep pyogenes
Strep pneumoniae
Haemophilus influenzae
What is Waldeyer’s tonsillar ring ?
In the pharynx at the back of the throat, there is a ring of lymphoid tissue.
6 areas of lymphoid tissue making up the adenoid, tubal, palatine tonsils and lingual tonsil
What are some features of tonsillitis in older children ?
Fever
Sore throat
Painful swallowing
What are some features of tonsillitis in younger children ?
Fever
Poor oral intake
Headache
Vomiting
Abdominal pain
What is seen on examination of tonsillitis ?
Red, inflamed
With or without exudate
What is the centor criteria and what are the featured examined for ?
Can be used to estimate the probability that tonsillitis is due to a bacterial infection
Fever over 38 degrees
Tonsillar exudates
Absence of cough
Tender anterior cervical lymph nodes
What is the fever pain score and what does it stand for ?
An alternative to the centor criteria and assessed probability of bacterial tonsillitis.
Fever
Purulence
Attended within 3 days of onset
Inflamed tonsils
No cough or coryza
What is the management of tonsillitis ?
Consider prescribing antibiotics or delaying it
Penicillin V for 10 days
Clarithomycin for if penicillin allergy
What are some complications of tonsillitis ?
Chronic tonsillitis
Peritonsillar abscess
Otitis media
Scarlet fever
Rheumatic fever
Post-strep glomerulonephritis
Post-strep reactive arthritis
