Infections Flashcards
Where is the commonest site for infection in young children?
Respiratory tract
What can the symptoms of mild viral illness be similar to?
Symptoms of mild viral illness may be similar to serious bacterial infection
Viral illness can also be severe
Viral & bacterial illness may coexist / collaborate
Epidemiology of global burden influenza under 5s
2018 estimated influenza episode in under 5s 109.5 million ( 63.1-190.6)
Attributable ALRI hospital admission 870000
Attributable ALRI Hospital deaths 15,000 total death
Admission & mortality Improved from previous WHO 2008 statisitics due to role out of Pneumococcal conjugate vaccine
How does the influenza resp tract infection work?
Primary viral pneumonitis
Co infection with other virus/ bacteria
Pathway to secondary bacterial infection: chest .. Also ear & brain
Epidemiology of RSV in children under 5
33 million RSV LRTI
3.6 million RSV hopitalisation
457000 RSV attributable mortality 97% in low and middle income countries
Both RSV and influenza association with secondary bacterial infection
Impact of immunsition flu and pneumococoal on hospital admissions
Children source of infection to adults
Passive immunization RSV all infants: previously just risk group
Pregnancy immunization RSV: protects mum and young infants
What bacteria cause pharyngitis/ tonsilitis, epiglottitis and otitis media?
Pharygitis/tonsilits: Gp A Strep, adenovirus, EBV
Epiglotitis: Haemophilus influenza b
Otitis media: Pneumococcus, haemophilus, GpA Strep, moraxella
What bacteria cause croup, tracheitis, pneumonia?
Croup: Para flu..+
Tracheitis: S.aureus, GpA Strep,
Pneumonia: GpAStrep, Pneumococcus, S.Aureus ,Haemophilus influenza..(non b),TB.
What bacteria causes atypical pneumonia, broncholitis
Atypical pneumonia: mycoplasma, chlamydia
Bronchiolitis: RSV, rhino, flu, adeno paraflu, metapneumo
If there is a possible bacterial infection what should you do?
Use most appropriate antibiotic
… not so easy when you don’t know the cause
Narrow vs broad spectrum where possible
Obtain samples ( micro. & virology ) to help rationalize treatment
Document your plan and infection you think you are treating
Follow local guidelines
Infection control
How does the antimicrobial stewardship treatment algorithm work?
Start Smart - Dont start antibiotics in absence of clinical evidence of bacterial infection
1. Take drug allergy history
2. Initiate prompt effective antibiotic treatment
3. comply with prescribing guidance
4. Document clinical indication
5. Include review
Then focus
1. CLinical review and decision at 48-72 hours
2. If needed STOP antibiotic
3. IV to oral switch
4. change antibiotic
5. continue
6. OPAT
What are the difficulties with new antimicrobials in children?
Tolerability , formulation, toxicity & pharmacokinetics different in children
Studies in children more difficult to do
Paediatric access to new drugs may be 10 yrs behind adult availability
Need for parallel paediatric trials
Which diseases without treatment/ early ID may develop coronary artery aneurysms and risk of long term cardiac disease
VZV: self limiting but mortality if secondary infection staph or strep
Significant national increase in VZV & GpA strep 2022-23
Impetigo staph / strep vs HSV stomatitis, simple cold sore, severe if eczema occasionaly causes encephalitis, ( enterovirus may mimic hand foot and mouth )
Meningococcal sepsis
HSP
Kawasaki disease (KD): fever, rash, stomatitis, periphery change, adenopathy, conjunctivitis
Features of Kawasaki disease
Red bloodshot eyes
Red swollen hand and feet
Strawberry tongue
High fever
Rash on body
Common in infants
Treatment for Kawasaki disease
Typical
4/5 features
with 5 day of fever
ECHO
IVIG
Asprin
+/- steroids
What is sepsis?
Overwhelming life threatening response to an infection resulting in tissue damage, organ failure and death….”
“Body’s overactive toxic response to Infection”
Sepsis 6 in children
Fast breathing
fit or convulsion
Looks mottled, bluish or pale
Non blanching rash
Lethargic or difficult to wake
Feels cold to touch
Sepsis 3 in any child under 5
Is not feeding
Vomiting
Havent had a wee or wet nappy in 12 hours
Traffic light system for identifying risk of serious illness
Slide 21 of infection paeds
Treatment for sepsis in child under 3 months
Under 3 months: FBC, Blood culture, CRP, Urine cultur, other investigatiosn as indicated
Under 1 month: as above and Lumbar puncture (LP)
1-3 months LP if: Unwell or WBC <5 or >15
IV antibiotics:
All infants under 1 months and 1-3 months if unwell or WBC <5 or>15
Treatment for sepsis in child over 3 months
Child over 3 months
Red features: FBC, Blood culture, CRP, Urine culture
LP if clinical features or unwell
CXR consider if clinical features
Amber features: as for red unless experienced paediatrician reviews
CXR if WBC >20 and temp>39
Green features: urine test, no blood tests
2 week old
Fever 24 hours at home
Not feeding well
Crying constantly when awake and waking less often for feeds
Temp 38.5
Pale, cool peripheries
WBC 4 ( normal 5-10)
Neut 1.0,(low) lymphocytes 3.0 (normal)
CRP 50
U&E normal
LFT deranged
CSF WBC 200
Glucose reduced
Protein elevated
What does he most likely have?
Bacterial Meningitis
Features of bacterial meningitis
Raised cell count (neutrophils)
Raised protein
Low glucose
Bacteria identified in blood or CSF culture or PCR
Features of viral meningitis
Raised cell count (lymphocytes)
Normal protein
Normal glucose
Virus identified in CSF, stool, throat or blood
HSV encephalitis
Causes of meningitis/ encephalitis under 3 months old
< 3 months: GpB strep,
Also: Ecoli, Listeria, pneumococcus, meningococcus
Cefotaxime ( ceftriaxone) & amoxicillin
Herpes simplex: aciclovir,
Enterovirus
Causes of meningitis/ encephalitis over 3 months old
Meningococcus, pneumococcus ( haemophilus influenza non b ),
Cefotaxime / ceftriaxone
Herpes simplex: aciclovir,
Enterovirus
8 year old
Cold previous week
New fever
complaining of headache before going to bed
Sleepy, confused when woken
Neck stiff when examined
Cool peripheries
Poor Capillary return
Possible meningococcal septicaemia
Features of meningococcal septicaemia
Caused by meningococcus, usually GpB in UK now
GpC previously common, GpA common in Africa/ middle east, , W&Y increasing in UK*
Serogroup defined by polysaccharide capsule of organism with no cross protection between strains
May or may not have associated meningitis
Clinical presentation, rapid onset septic shock
Management cefotaxime/ ceftriaxone, early PICU
Septicaemia with other organisms may mimic: Pneumococcus, Toxin producing strains GpA Strep, Staph aureus
Symptoms of meningitis
Neck stiffness
Sensitivity to light.
( not reliable in young children)
Drowsy/ irritable
Vomit
Headache
Full fontaelle
Symptoms of meningitis septicaemia
Red/purple non-blanching rash.
Cold hands and feet.
Tachypnoea.
Flu like symptoms
4 month old
No previous health problems
Recurrent cough and noisy breathing past 3 days
Sl indrawing RR 60, nasal flaring, alert, well perfused
Temp 37.8
Bilateral crackles and wheese
What is it?
Bronchiolitis
What are some causes of bronchiolitis?
RSV
Paraflu
Influenza A/B
Rhinovirus
Adenovirus
H. Metapneumo
Corona ( various
4 month old
No previous health problems
Recurrent cough and noisy breathing past 3 days
Sl indrawing RR 60, nasal flaring, alert, well perfused
Temp 37.8
Bilateral crackles and wheese
weeks later
Never really got better
Not feeding well
Clearly lost weight since last admission
RR 60
Widespread crackles & respiratory distress
Temp 38.2
PICU team alerted
WBC 4 (neut 3.0, lymphocytes 1.0 ( 2.5-4))
CRP 23
Blood culture , urine culture no growth
still RSV +ve and now para flu +ve
IgG 1.5 ( 2.5-6)
IgA < 0.04
IgM <0.08 ( 0.5 – 1.5
What is up with the child?
Bronchial secretions PCP ( pneumocystis pneumonia/jirovecii)
“ opportunistic infection”
Immune deficiency in children
Infection common in children
Immune deficiency rare : Sever Combined Immune deficiency
(SCID) 1 in 50-60,00
Severe disease presenting in neonates/ infants, immunological emergency
Not just infectious presentation:
Failure to thrive, skin problems , chronic chest problems/organomegaly/adenopathy
Normal infant lymphocyte count >2.5
Newborn screening for SCID on neonatal dry blood spot “TRECs” indication of thymic out put since September 2021
Genetic Immune defects may present in older child/Adults
Immune defects associated with malignancy, autoimmunity and allergic disease
Pathophysiology of immune deficiency
-Inadequate number cell Number : X linked agammaglobulinaemia/ SCID/ Congenital neutropenia
-Defect in cell function: chronic granulomatous disease neutrophil function defect
Defect in cytokine production/ intracellular messaging
10 warning signs of primary immunodeficiency
- 4 or more new ear infections within one year
- 2 or more sinus infections in a year
- 2 or more months on antibiotics with little effect
- 2 or more pneumonia in a year
- Failure to gain weight or grow normally
- Recurrent deep skin or organ abcesses
- Persistent thrush in mouth or fungal infection in skin
- Need IV antibiotics to clear infections
- 2 or more deep seated infections including septicaemia
Epidemiology of Severe combined immunodeficiency
US Experience 2010-2013
11 programmes, > 3 million births
52 SCID, 1:58000 births
411 non SCID lymphopenia: Di George, Trisomy 21 CHARGE, Trisomy 18, Ataxia telangiectasia
False positive more likely in preterm infants
UK estimates annually: 266 false positive, 31 Lymphopenic not SCID, 17 SCID
Prevent 6.3 SCID deaths annually
Neonatal BCG: plan to delay to 6 weeks
Who do we investigate for SCID?
Frequent or unusually severe infections
Infection with unusual organism
Family history
Unusual inflammatory/ autoimmune or malignancy phenotype
Low threshold in children with underlying syndromic/ chromosomal problems with infection
What tests to do for SCID?
FBC : low total WBC, neutrophil or lymphocytes
Total Ig GAM +/-E
Responses to routine immunisations
Lymphocyte subsets: numbers of T and B cells
Lymphocyte function
Genetic panels
Treatment for SCID
Antibiotic / antiviral prophylaxis
Prompt treatment of infections
Replacement immunoglobulin ( usually subcutaneous infusion at home weekly)
Bone marrow transplant
Close Collaboration with other specialties : respiratory, rheumatology, gastroenterology, haematology, genetics
How do vaccines work
Generate immune response: T ( cell mediated) and B cells (antibody) for organism
Antibody against toxin
Induce immunological memory
Protein antigens stronger stimulation eg tetanus toxoid vs Polysaccharide capsule meningo/ Pneumo
Antibodies (B cell memory): easily measured
Specific T cell memory ( more difficult to measure)
Herd immunity
Protective not harmful immune response
How do passive immunity and active immunity work?
Passive immunity: HBIG, ,VZIG, Rabies Ig, HNIG RSV
Active:
Live attenuated : MMR, BCG, nasal flu, rotavirus
Inactivated: whole cell pertussis
Inactivated toxin: Diptheria, Tetanus
Recombinant components: acellular pertussis
Conjugate vaccine: Bacterial Polysaccharide+protein carrier
Cell wall/ envelope components: Flu, MenB
UK vaccine preventable diseases
Tetanus
Diptheria
Whooping cough
Polio
Measles
Mumps
Rubella
Hib
Men C
Prevnar 13
Pneumovax*
Meningococcus ACWY
Varicella*
TB*
Hepatitis B
Influenza*
Rotavirus
HPV
Men B
Rotavirus
Other meningitis vaccines
Gp B meningococcus (OMP veiscle) : Introduced Sept 2015
Impact on carriage unclear
GpACWY meningococcus : Summer 2015 (teens)
Haemophilus influenza B : Meningitis, epiglotitis
Vaccine introduced 1992, disease virtually disappeared
Pneumococcus: 100+ different serotypes
Most invasive disease UK caused by ( was caused by?) 13 serotypes in Prevnar 13 ( conjugate, immunogentic in infants 2010)
Meningitis, pneumonia, empyema, bacteraemia, otitis media still occur
Problems with serotype replacement
Pneumovax: 23 serotype, non immunogenic in infants , poor immune memory
Epidemiology of Pertussis (Whooping cough)
Vaccine introduced 1957
Scare in 1970s reduced vaccine uptake
wP vaccine replaced with less reactogenic vaccine acellular pertussis 2000
2012 14 infants died in UK
Unrecognsied burden of disease in adults / older children
September 2012 pertussis immunization offered to pregnant women
2013 3 Uk infant death all to infants of unimmunsied mothers
Now routine dTaP , Flu, and COIVD offered in pregnancy
250% increase in whooping cough 2023 ? Reduced pregnancy immunsiation & reduced population immunity
Immunisation challenges
Waning vaccine induced immunity
Herd immunity
Immunological memory
Infectious disease Epidemiology and reporting
Vaccine strategy
Anti vaccine campaigns/ vaccine hesitancy
Access to immunization
Conflict/ famine/ widening health inequality
COVID
UNICEF Apr 2023 67 million children missed out on vaccines past 3 years
What is the R value
R value < 1 : less than one person infected by an index case
Increasing R value increasing infectivity
Infectivity affected by degree of contact, duration of index illness & host and index vaccination status
Measles will infect 12-18 unimmunized exposed individuals
2 yrold
Arrived in UK 2 weeks ago from Sierra Leone to live with mum
Cranky, temp 39, RR 40, well perfused, no rash
Hb 7.8 (low), Pl 180 (low normal),
CRP 90
CXR bronchial wall thickening
Malaria film & rapid test x3 negative
Respiratory viral swabs sent
IV ceftriaxone ?
What is it
Typhoid
12 year old
Arrived in UK from Zambia 6 months ago
Chicken pox 4 weeks ago prolonged illness, 2 weeks antibiotics
Readmitted 2 weeks later
Cough, Temp 39, tachycardic, RR 50
Healing VZV scars
WBC 20 CRP 75
What other investigations do you want?
What other infections might a child born in sub-Saharan Africa be at risk of ?
Pneumococcus, GP A strep, Staphococcus aureus
Tuberculosis
Features of TB
Latent disease: asymptomatic, uninfectious, treat to prevent disease in future
Active disease ( symptomatic/ clinical evidence eg Xray, Lymphnodes): mortality high if untreated
Children often not infectious ( older children may be)
Diagnosis 1. symptoms: fever sweats wt loss cough 2. contact tracing 3. tests: sputum, tissue, X ray, Mantoux, IFN gamma blood tests
BCG some protection, predominantly against neonatal TB meningitis
Epidemiology of TB
9.4 x 106 cases TB annually world wide
1 x 106 in children but may be underestimate
Rates of TB overall are falling world wide
BUT incidence of Drug resistant TB increasing
Children still dying unnecessarily
Ongoing infection in children provides a pool for ongoing infection in the community
Risk of congenital (perinatal) infection
HIV* maternal Rx
Hepatitis B* Immunisation at birth
CMV: treatment of infant modifies disease
Rubella
HSV: intervention pre & peri-delivery but not screened
VZV: intervention if early neontal
TB* maternal Rx
Syphilis* maternal Rx
GpB strep*? Maternal peri-delivery Rx
HIV Features
With treatment should live relatively normal life to late adulthood
Transmission mother to infant 25% with no intervention
Pregnant mother given medication with controlled infection
Transmission in UK now «_space;1% due to screening and treatment in pregnancy
Increased risk if late presentation/ poor compliance/ country or origin higher rates of infection
C section necessary if detectable maternal virus
Infant medication 2-4 weeks
Breast feeding : not advised in UK but yes in resource poor setting
Infection still a risk if: mum not screened in pregnancy ORBreast feeding with detectable virus OR discordant couples
