Infection Flashcards
Inactivated vaccines involve 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 are?
Polio
Flu vaccine
Hepatitis A
Rabies
Are inactivated vaccines safe in immunocompromised patients?
They cannot cause an infection and are safe for immunocompromised patients, although they may not have an adequate response.
Subunit and conjugate vaccines only contain parts of the organism used to stimulate an immune response. They also cannot cause infection and are safe for immunocompromised patients. Examples of subunit and conjugate vaccines are?
Pneumococcus
Meningococcus
Hepatitis B
Pertussis (whooping cough)
Haemophilus influenza type B
Human papillomavirus (HPV)
Shingles (herpes-zoster virus)
What are subunit and conjugate vaccines?
Subunit and conjugate vaccines only contain parts of the organism used to stimulate an immune response.
They also cannot cause infection and are safe for immunocompromised patients.
Live attenuated vaccines contain a weakened version of the pathogen. They are still capable of causing infection, particularly in immunocompromised patients.
What are ecamples?
Measles, mumps and rubella vaccine: contains all three weakened viruses
BCG: contains a weakened version of tuberculosis
Chickenpox: contains a weakened varicella-zoster virus
Nasal influenza vaccine (not the injection)
Rotavirus vaccine
Which types of vaccinations cannot cause infection and are therefore safe in immunocomprimised patients?
Inactivated vaccines
Subunit and conjugate vaccines
Toxin vaccines
How do toxin vaccines work and what are examples?
Toxin vaccines contain a toxin that is normally produced by a pathogen. They cause immunity to the toxin and not the pathogen itself. Examples are the diphtheria and tetanus vaccines.
At what ages are vaccines required?
8 weeks
12 weeks
16 weeks
1 year
Yearly from ages 2-8
3 years 4 months
12-13 years
14 years
What vaccines are given at 8 weeks?
6 in 1 vaccine (diphtheria, tetanus, pertussis, polio, haemophilus influenzae type B (Hib) and hepatitis B)
Meningococcal type B
Rotavirus (oral vaccine)
What vaccines are given at 12 weeks?
6 in 1 vaccine (again)
Pneumococcal (13 different serotypes)
Rotavirus (again)
What vaccines are given at 16 weeks?
6 in 1 vaccine (again)
Meningococcal type B (again)
What vaccines are given at 1 year?
2 in 1 (haemophilus influenza type B and meningococcal type C)
Pneumococcal (again)
MMR vaccine (measles, mumps and rubella)
Meningococcal type B (again)
Which vaccine is given yearly at 2-8 years?
Influenza vaccine (nasal vaccine)
What vaccines are given at 3 years and 4 months?
4 in 1 (diphtheria, tetanus, pertussis and polio)
MMR vaccine (again)
What vaccine is given at 12-13 years?
Human papillomavirus (HPV) vaccine (2 doses given 6 to 24 months apart)
Which vaccines are given at 14 years?
3 in 1 (tetanus, diphtheria and polio)
Meningococcal groups A, C, W and Y
When is the 6 in 1 vaccine (diphtheria, tetanus, pertussis, polio, haemophilus influenzae type B (Hib) and hepatitis B) given?
8 weeks, 12 weeks, 16 weeks,
When is the Meningococcal type B vaccine given?
8 weeks, 16 weeks, 1 year
When is the MMR vaccine given?
1 year
3 years 4 months
When is the Rotavirus vaccine given?
8 weeks, 12 weeks
When is the pneumococcal vaccine given?
12 weeks, 1 year
When and to whom is the BCG vaccination offered?
The BCG vaccine is offered from birth to babies who are at higher risk of tuberculosis.
These are babies with relatives from countries of high TB prevalence or who live in urban areas with a high rate of TB.
It may also be given to children arriving from areas of high TB prevalence or in close contact with people that have TB.
The current NHS HPV vaccine is Gardasil, which strains does this protect against?
Strains 6 and 11 cause genital warts
Strains 16 and 18 cause cervical cancer
Counselling parents on the HPV vaccination?
They are often upset because they believe this implies their daughter or son is sexually promiscuous.
Focus on the fact it needs to be given before they become sexually active and that it protects them from cervical cancer and genital warts.
HPV is very common and infection is the number one risk factor for cervical cancer.
What type of evidence supported the link between MMR and Autism?
Anecdotal
What is sepsis?
Sepsis is a syndrome that occurs when an infection causes the child to become systemically unwell.
It is the result of a severe systemic inflammatory response.
It is a life threatening condition and there should be a low threshold for treating suspected sepsis.
Pathophysiology of sepsis
The causative pathogens are recognised by macrophages, lymphocytes and mast cells.
These cells release vast amounts of cytokines, such as interleukins and tumor necrosis factor, to alert the immune system to the invader.
These cytokines activate other parts of the immune system.
This immune activation leads to further release of chemicals such as nitrous oxide that causes vasodilation.
The immune response causes inflammation throughout the body.
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 volume.
The oedema around blood vessels creates a space between the blood and the tissues, reducing the amount of oxygen that reaches the tissues.
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, as they are being used up to form the blood clots.
This leads to thrombocytopenia, haemorrhages and an inability to form clots and stop bleeding.
This is called disseminated intravascular coagulopathy (DIC).
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?
Septic shock is diagnosed when sepsis has lead to cardiovascular dysfunction.
The arterial blood pressure falls, resulting in organ hypo-perfusion.
This leads to a rise in blood lactate as the organs begin anaerobic respiration.
How is septic shock treated?
Septic shock should be treated aggressively with IV fluids to improve the blood pressure and tissue perfusion.
If IV fluid boluses fail to improve the blood pressure and lactate level, children should be escalated to the high dependency or intensive care unit where inotropes (such as noradrenalin) can be considered.
Inotropes stimulate the cardiovascular system and improve blood pressure and tissue perfusion.
What is the role of inotropes in HDU/ITU management of septic shock?
Inotropes stimulate the cardiovascular system and improve blood pressure and tissue perfusion.
Signs of paediatric sepsis?
Deranged physical observations
Prolonged capillary refill time (CRT)
Fever or hypothermia
Deranged behaviour
Poor feeding
Inconsolable or high pitched crying
High pitched or weak cry
Reduced consciousness
Reduced body tone (floppy)
Skin colour changes (cyanosis, mottled pale or
ashen)
What is meant by shock?
Shock involves circulatory collapse and hypoperfusion of organs.
There are NICE guidelines from 2019 that cover the assessment of children under 5 year with a fever. They recommend using a traffic light system for the assessment of serious illness in these children. This categorises children as green (low risk), amber (intermediate risk) or red (high risk). Read through the table in the NICE guidelines describing the features of each to familiarise yourself with the signs to look out for.
Patients are categorised based on examination findings in various systems, such as?
Colour: normal colour versus cyanosis, mottled pale or ashen
Activity: active, happy and responsive versus abnormal responses, drowsy or inconsolable cry
Respiratory: normal breathing versus respiratory distress, tachypnoea or grunting
Circulation and hydration: normal skin and moist membranes versus tachycardia, dry membranes or poor skin turgor
Other: other concerning signs, such as fever > 5 days, non blanching rash, seizures or high temperatures < 6 months
All infants under what age with a temperature of 38ºC or above need to be treated urgently for sepsis, until proven otherwise?
3 months
All infants under 3 months with a temperature of what need to be treated urgently for sepsis, until proven otherwise.
38 degrees Celsius or above
Paediatric sepsis - immediate management?
Give oxygen if the patient has evidence of shock or oxygen saturations are below 94%
Obtain IV access (cannulation)
Blood tests, including a FBC, U&E, CRP, clotting screen (INR), blood gas for lactate and acidosis
Blood cultures, ideally before giving antibiotics
Urine dipstick and laboratory testing for culture and sensitivities
Antibiotics according to local guidelines. They should be given within 1 hour of presentation.
IV fluids. 20ml/kg IV bolus of normal saline if the lactate is above 2 mmol/L or there is shock. This may be repeated.
Paediatric sepsis further management following initial management?
Chest xray if pneumonia is suspected
Abdominal and pelvic ultrasound if intra-abdominal infection is suspected
Lumbar puncture if meningitis is suspected
Meningococcal PCR blood test if meningococcal disease is suspected
Serum cortisol if adrenal crisis is suspected
Continue antibiotics for 5 – 7 days if a bacterial
infection is suspected or confirmed.
Alter the antibiotic choice and duration once a source of infection is found and an organism is isolated.
Bacterial culture and sensitivities can be very helpful in guiding antibiotics.
A microbiologist can provide advice on the choice and duration of antibiotics.
Consider stopping antibiotics where there is a low suspicion of bacterial infection, the patient is well and blood cultures and two CRP results are negative at 48 hours.
When should you consider stopping antibiotics in ?paediatric sepsis?
Low suspicion of bacterial infection,
Patient is well and blood cultures
Two CRP results are negative at 48 hours
What is infectious mononucleosis and what causes it?
Infectious mononucleosis (IM) is a condition caused by infection with the Epstein Barr virus (EBV).
It is commonly known as the “kissing disease”, “glandular fever” or “mono”.
This virus is found in the saliva of infected individuals.
Infection may be spread by kissing or by sharing cups, toothbrushes and other equipment that transmits saliva.
EBV is secreted in the saliva of infected individuals and can be infectious several weeks before the illness begins and intermittently for the remainder of the patient’s life.
Is infection with mononucleosis usually symptomatic?
Most people are infected with EBV as children, when it causes very few symptoms.
When infection occurs in teenagers or young adults, it causes more severe symptoms.
It is the symptomatic infection with EBV that is called infectious mononucleosis.
Typical symptoms are fever, sore throat and fatigue.
When are patients infectious with EBV?
EBV is secreted in the saliva of infected individuals and can be infectious several weeks before the illness begins and intermittently for the remainder of the patient’s life.
What might you suspect in an adolescent with a sore throat, who develops an itchy rash after taking amoxicillin?
Mononucleosis
EBV infection causes an intensely itchy maculopapular rash in response to amoxicillin or cefalosporins
Features of EBV infection?
Fever
Sore throat
Fatigue
Lymphadenopathy (swollen lymph nodes)
Tonsillar enlargement
Splenomegaly and in rare cases splenic rupture
In infectious mononucleosis, the body produces something called heterophile antibodies - what are these and when are they formed?
Antibodies that are more multipurpose and not specific to the EBV antigens.
It takes up to 6 weeks for these antibodies to be produced.
Which tests can be used to detect hetrophile antibodies?
Monospot test: this introduces the patient’s blood to red blood cells from horses. Heterophile antibodies (if present) will react to the horse red blood cells and give a positive result.
Paul-Bunnell test: this is similar to the monospot test but uses red blood cells from sheep.
Heterophile antibodies in ?IM - sensitivity and specificity
Almost 100% specific for infectious mononucleosis, however not everyone who has IM produces heterophile antibodies, and it can take up to six weeks for the antibodies to be produced. Therefore they are only 70 – 80% sensitive.
EBV - specific antibody tests?
The IgM antibody rises early and suggests acute infection
The IgG antibody persists after the condition and suggests immunity
Management and prognosis of infectious mononucleosis?
Infectious mononucleosis is usually self limiting. The acute illness lasts around 2 – 3 weeks, however it can leave the patient with fatigue for several months once the infection is cleared.
Patients are advised to avoid alcohol, as EBV impacts the ability of the liver to process the alcohol.
Patients are advised to avoid contact sports due to the risk of splenic rupture.
Emergency surgery is usually required if splenic rupture occurs.
Potential complications of infectious mononucleosis?
Splenic rupture
Glomerulonephritis
Haemolytic anaemia
Thrombocytopenia
Chronic fatigue
EBV infection is associated with certain cancers, for example?
Burkitt’s lymphoma.
What is HIV, what is AIDS?
HIV refers to the human immunodeficiency virus that causes the infection that makes someone HIV positive.
AIDS refers to the acquired immunodeficiency syndrome that occurs at the end stages of a HIV infection, once the infection has affected the immune system enough to make the person susceptible to recurrent and unusual infections.
AIDS is usually referred to in the UK as late stage HIV.
Basic pathophysiology of HIV?
HIV is an RNA retrovirus. HIV-1 is most common type. HIV-2 is rare outside West Africa.
The virus enters and destroys the CD4 T helper cells.
An initial seroconversion flu like illness occurs within a few weeks of infection.
The infection is then asymptomatic until it progresses and the patient becomes immunocompromised and beings developing AIDS defining illnesses and opportunistic infections, potentially years later.
How is HIV spread?
Unprotected anal, vaginal or oral sexual activity
Mother to child at any stage of pregnancy, birth or breastfeeding. This is referred to as vertical transmission.
Mucous membrane, blood or open wound exposure to infected blood or bodily fluids. This could be through sharing needles, needle-stick injuries or blood splashed in an eye.
How is mode of delivery determined to prevent HIV transmission to the baby in a mother who is HIV positive?
Normal vaginal delivery is recommended for women with a viral load < 50 copies / ml
Caesarean sections are considered in patients with > 50 copies copies / ml and in all women with > 400 copies / ml
IV zidovudine should be given during the caesarean if the viral load is unknown or there are > 10000 copies / ml
When should IV zidovudine be given to prevent HIV during c section?
IV zidovudine should be given during the caesarean if the viral load is unknown or there are > 10000 copies / ml
Under what viral loads is considered ‘safe’ for a vaginal delivery in terms of vertical HIV transmission?
< 50 copies / ml
What influences what prophylaxis treatment may be given to the baby born to a mother who is HIV positive?
High risk vs low risk - determined by viral load
High risk: mother has < 50 copies / ml
Low risk: mother has > 50 / ml
Prophylaxis of HIV following birth for a baby born to a mother with viral load of < 50 copies / ml
zidovudine for 4 weeks
Prophylaxis of HIV following birth for a baby born to a mother with viral load of > 50 copies / ml
zidovudine, lamivudine and nevirapine for 4 weeks
For how long following birth are babies born to mothers with HIV given prophylactic treatment?
4 weeks
HIV and breastfeeding?
HIV can be transmitted during breastfeeding, even if the mother’s viral load is undetectable.
Breastfeeding is never recommended for mothers with HIV, however if the mum is adamant and the viral load is undetectable, sometimes it is attempted with close monitoring by the HIV team.
What options exist for HIV testing?
HIV antibody screen: this tests whether the immune system has created antibodies due to exposure to the HIV virus. This is the standard screening test, but it can give false positive in babies of HIV positive mums, due to maternal antibodies that cross the placenta. It can take up to 3 months for antibodies to develop after exposure to the virus.
HIV viral load: this tests directly for viruses in the blood. This will never be falsely positive, but may come back as “undetectable” in patients on antiretroviral therapy.
Problem with HIV antibody screen in a baby, and why it occurs?
It can give false positive in babies of HIV positive mums, due to maternal antibodies that cross the placenta. It can take up to 3 months for antibodies to develop after exposure to the virus.
When screening a child for HIV, what are is the advantage and disadvantage of viral load testing?
This will never be falsely positive (unlike in antibody screen, where maternal antibodies may cross placenta), but may come back as “undetectable” in patients on antiretroviral therapy.
When to test children for HIV?
Babies to HIV positive parents
When immunodeficiency is suspected, for example where there are unusual, severe or frequent infections
Young people who are sexually active can be offered testing if there are concerns
Risk factors such as needle stick injuries, sexual abuse or IV drug use
Babies to HIV positive parents are tested how and when?
HIV viral load test at 3 months. If this is negative, the child has not contracted HIV during birth and will not develop HIV unless they have further exposure.
HIV antibody test at 24 months. This is to assess whether they have contracted HIV since their 3 month viral load, for example through breast feeding. If the 3 month test is negative and they are not breastfed, this should be negative.
Management of HIV in children?
Treatment should be coordinated by a specialist in paediatric HIV. The key principles of medical care are:
Antiretroviral therapy (ART) to suppress the HIV infection
Normal childhood vaccines, avoiding or delaying live vaccines if severely immunosuppressed.
Prophylactic co-trimoxazole (Septrin) for children with low CD4 counts, to protect against pneumocystis jirovecii pneumonia (PCP)
Treatment of opportunistic infections
The aim of antiretroviral therapy (ART) is to achieve a normal CD4 count and undetectable viral load. As a general rule, when a patient has a normal CD4 and undetectable viral load on ART, treat their physical health problems (e.g. routine chest infections) as you would an HIV negative patient. When prescribing medications check for interactions with the HIV therapy.
The paediatric HIV multidisciplinary team should be involved in:
Regular follow up to monitor growth and development
Dietician input for nutritional support when required
Parental education about the condition
Disclosing the diagnosis to the child is often delayed until they are mature enough
Psychological support
Specific sex education in relation to HIV when appropriate
In childhood HIV, treatment should be coordinated by a specialist in paediatric HIV. The key principles of medical care are what?
Antiretroviral therapy (ART) to suppress the HIV infection
Normal childhood vaccines, avoiding or delaying live vaccines if severely immunosuppressed.
Prophylactic co-trimoxazole (Septrin) for children with low CD4 counts, to protect against pneumocystis jirovecii pneumonia (PCP)
Treatment of opportunistic infections
The aim of antiretroviral therapy (ART) is to achieve a normal CD4 count and undetectable viral load. As a general rule, when a patient has a normal CD4 and undetectable viral load on ART, treat their physical health problems (e.g. routine chest infections) as you would an HIV negative patient.
When prescribing medications check for interactions with the HIV therapy.
What is mumps?
Mumps is a viral infection spread by respiratory droplets. The incubation period is 14 – 25 days. Mumps is usually a self limiting condition that lasts around 1 week. Management is supportive, and involves treating the complications if they occur.
How is mumps spread?
Respiratory droplets
What is the incubation period of mumps?
14-25 days
Usual course of mumps?
Incubation 14-25 days
1 week of self limiting symptoms
What aspect of the history is essentiel when considering ?mumps?
Taking a vaccination history is essential when considering a diagnosis of mumps. The MMR vaccine offers around 80% protection against mumps.
How does mumps present?
Patients experience an initial period of flu-like symptoms known as the prodrome. These occur a few days before the parotid swelling:
Fever
Muscle aches
Lethargy
Reduced appetite
Headache
Dry mouth
Parotid gland swelling, either unilateral or bilateral, with associated pain is the key feature that should make you consider mumps.
It can also present with symptoms of the complications, such as:
Abdominal pain (pancreatitis)
Testicular pain and swelling (orchitis)
Confusion, neck stiffness and headache (meningitis or encephalitis)
Potential symptoms of the complications of mumps?
Abdominal pain (pancreatitis)
Testicular pain and swelling (orchitis)
Confusion, neck stiffness and headache (meningitis or encephalitis)
Management of mumps?
The diagnosis can be confirmed using PCR testing on a saliva swab. The blood or saliva can also be tested for antibodies to the mumps virus.
Mumps is a notifiable disease, meaning you need to notify public health of any suspected and confirmed cases.
Management is supportive, with rest, fluids and analgesia. Mumps is a self limiting condition. Management of complications is also mostly supportive.
Complications of mumps?
Pancreatitis
Orchitis
Meningitis
Sensorineural hearing loss
What is hepatitis B and how is it spread?
Hepatitis B is a DNA virus. It is transmitted by direct contact with blood or bodily fluids.
This may occur during sexual intercourse or sharing needles, for example amongst IV drug users or tattoos. It can also be passed through sharing contaminated household products such as toothbrushes or contact between minor cuts or abrasions.
It can also be passed from mother to child during pregnancy and delivery. This is known as vertical transmission.
How does hepatitis B infection affect children differently from adults?
Most children fully recover from the infection within 2 months, however a portion go on to become chronic hepatitis B carriers. In these patients the virus DNA has integrated into their own DNA and they continue to produce the viral proteins. The risk of developing chronic hepatitis B after exposure is:
90% for neonates
30% for children under 5
Under 10% for adolescents
Most children with chronic hepatitis B are asymptomatic, with normal growth and development and normal liver function tests.
Less than 5% will develop liver cirrhosis and less than 0.05% will develop hepatocellular carcinoma before adulthood.
These risks increase once they enter adulthood.
What are the different antigens and antibodies tested for in relation to Hep B and what do they indicate?
Surface antigen (HBsAg) – active infection
E antigen (HBeAg) – marker of viral replication and implies high infectivity
Core antibodies (HBcAb) – implies past or current infection
Surface antibody (HBsAb) – implies vaccination or past or current infection
Hepatitis B virus DNA (HBV DNA) – this is a direct count of the viral load
What bacteria is commonly known as meningococcus?
Neisseria meningitidis is a gram-negative diplococcus bacteria
They are circular bacteria (cocci) that occur in pairs (diplo-)
What does a rough sandpaper rash which is spreading with flushed cheeks and strawberry tongue suggest?
Scarlett fever caused by an exotoxin produced by the streptococcus pyogenes (group A strep) bacteria.
How does Parovirus 19 infection present?
Parvovirus infection starts with mild fever, coryza and non-specific viral symptoms such as muscle aches and lethargy.
After 2 – 5 days the rash appears quite rapidly as a diffuse bright red rash on both cheeks, as though they have “slapped cheeks”.
A few days later a reticular mildly erythematous rash affecting the trunk and limbs appears that can be raised and itchy. Reticular means net-like.
Roseola infantum presentation?
It presents 1 – 2 weeks after infection with a high fever (up to 40ºC) that comes on suddenly, lasts for 3 – 5 days and then disappears suddenly.
There may be coryzal symptoms, sore throat and swollen lymph nodes during the illness.
When the fever settles, the rash appears for 1 – 2 days.
The rash consists of a mild erythematous macular rash across the arms, legs, trunk and face and is not itchy.
