Microbiology, infection, immunity, and allergy Flashcards
What is the main cause of UTIs in children?
E coli
What is the first line treatment for E coli UTI?
IV cefuroxime for 7 days
What is the oral switch with an E coli UTI?
Trimethoprim but may need full course IV
What is the worry with E coli UTIs?
Extended spectrum beta-lactamase producers - resistant to all penicillin and cephalosporins as will break them down
What are the alternative treatments for ESBL UTIs?
Meropenem - if suspect resistant and unsure of sensitivities (v broad spectrum)
Ideally - gentamicin
What should you be careful with with gentamicin?
Kidney function - often not an issue in children
How do you treat osteomyelitis/septic arthritis in over 3 months?
IV cefuroxime - liaise with microbiologists
Treat for min 6 weeks
IV -> PO switch once responding but patient led
Long term therapy - ?out patient antibiotic therapy
What might gram positive cocci in clusters that are golden on blood agar be?
S aureus
How do you treat MRSA?
IV teicoplanin/vancomycin
PO clindamycin/doxycycline (not under 12)
Depends on sensitivities
What is the first line treatment for bacterial meningitis/meningococcal sepsis?
IV cefotaxime/ceftriaxone
What investigations do you do for bacterial meningitis/menigococcal speticaemia?
Blood cultures
EDTA blood for PCR
CSF
What might gram negative diplococci be?
Neisseria meningitides
What prophylaxis do you give to meningitis contacts?
Ciprofloxacin stat dose
Rifampicin
What must you report to PHE?
All meningitis
All invasive meningococcal disease
All encephalitis
24/7
What might gram +ve diplococci, with alpha haemolysis that is optochin sensitive be?
Strep pneuominae
What is strep pneumoniae sensitive to?
IV benzylpenicillin or PO amox
What is the first line treatment for CAP?
Mild - oral amox
Severe - IV benzylpenicillin
Length depends on response
How common is infection?
Commonest single cause of admission of children to hospital
Younger > older children
Respiratory tract commonest site
May need antibiotic/antiviral treatment or just supportive care eg O2, fluids
Few rapid tests so treatment based on clinical picture
Symptoms of mild viral illness may be similar to serious bacterial infection
Viral illness can also be severe
What can cause pharyngitis/tonsilitis?
Group A strep, adenovirus, EBV
What can cause epiglotitis?
HiB
What causes whooping cough?
Pertussis
What can cause otitis media?
Pneumococcus, haemophilus, GpA strep, moraxella
What can cause croup?
Parainfluenza virus
What can cause tracheitis?
S aureus, Strep A, haemophilus
What can cause pneumonia?
Strep A, pneumo, staph, haemophilus, TB
What can cause atypical pneumonia?
Mycoplasma, chlamydia
What can cause bronchiolitis?
RSV, rhinovirus, flu, adenovirus, parainfluenza, metapneumo
What causes problems with varicella zoster virus?
Self-limiting but mortality if secondary infection staph or strep
What are the symptoms of HSV infection?
Stomatitis
Simple cold sore
Occasional encephalitis
Severe is eczema
What are the symptoms of Kawasaki disease?
Fever, rash, stomatitis
Periphery change
Adenopathy
Raised platelets
Coronary artery aneurysm
Unknown cause
What is important to remember with antibiotics?
Use the most appropriate antibiotic - not easy when you don’t know the cause
Narrow vs broad spectrum where possible
Minimum time period necessary
Follow local guidelines
Infection control
Start smart then focus PHE
Tolerability, formulation, toxicity and pharmacokinetics different in children
Paediatric access to new drugs may be 10 years behind adult availability
Need to come in a form that children can swallow
More vulnerable to antibiotic resistance
What investigations should you do for a child under 3 months with a fever without focus?
FBC
Blood culture
CRP
Urine culture
Other investigations as indicated
What investigations should you do for a child under 1 month with a fever without focus?
Same as child under 3 months
LP
When should you do a LP in a child 1-3 months of age?
Unwell or WBC < 5 or > 15
When should you give IV antibiotics?
All infants under 1 month and 1-3 months if unwell or WBC < 5 or > 15
What investigations should you do for a child under 1 month with a fever without focus?
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
- Urine test
- No bloods
What are the green features?
Normal colour
Responds normally to social cues
Content/smiles
Stays awake/awakens quickly
Strong normal cry/not crying
Normal skin and eyes
Moist mucous membranes
What are the amber features?
Pallor reported by parent/carer
Not responding normally to social cues
No smile
Wakes only with prolonged stimulation
Decreased activity
Nasal flaring
Tachypnoea
- RR > 50 age 6-12 months
- > 40 aged > 12 months
O2 sat < 95% OA
Crackles in chest
Tachycardia
- > 160 age < 12 months
- > 150 age 12-24 months
- > 140 2-5 years
CRT > 3 s
Dry mucous membranes
Poor feeding
Reduced urine output
Age 3-6 months temp > 39
Fever for > 5 days
Rigors
Swelling of limb or joint
Non-weight bearing limb/not using extremity
What are the red signs?
Pale/mottled/ashen/blue
No response to social cues
Appears ill to a healthcare professional
Doesn’t wake up or if roused does not stay awake
Weak, high-pitched or continuous cry
Grunting
Tachypnoea RR > 60
Moderate or severe chest indrawing
Reduced skin turgor
Age < 3 months temp > 38
Non-blanching rash
Bulging fontanelle
Neck stiffness
Status epilepticus
Focal neurological signs
Focal seizures
What CSF findings do you get for bacterial meningitis?
Raised white cell count (neutrophils)
Raised protein
Low glucose
Bacteria identified in blood or CSF culture or PCR
What CSF findings do you get for viral meningitis?
Raised white cell count (lymphocytes)
Normal protein
Normal glucose
Virus identified in CSF, stool, throat, or blood
HSV encephalitis
What are the main causes of bacterial meningitis in under 3 months olds?
Gp B strep
E coli
Listeria
Pneumococcus
Meningococcus
How do you treat bacterial meningitis in under 3 month olds?
Cefotaxime and amoxicillin
What are the main causes of viral meningitis in children?
HSV - acyclovir
Enterovirus
What are the main causes of bacterial meningitis in over 3 month olds?
Meningococcus
Pneumococcus
H influenza
How do you treat bacterial meningitis in over 3 month olds?
Cefotaxime/cetriaxone
What are the main symptoms of meningitis?
Neck stiffness
Photophobia (not reliable in young children)
Drowsy/irritable
Vomiting
Headache
Full fontanelle
What are the symptoms of septicaemia in children?
Red/purple non-blanching rash
Cold hands and feet
Tachypnoea
Flu like symptoms
What are the main causes of bronchiolitis?
RSV
Parainfluenza virus
Influenza A/B
Rhinovirus
Adenovirus
Bronchial secretions PCP (pneumocysitis pneumonia/jiroveci)
What is the immune function in children like?
Immune levels at 60% of total adult levels in baby
Newborns make IgM and some IgA but most of IgG is maternal
How common is immune deficiency?
1 in 2000 births underlying immune deficiency
1 in 50-60,000 severe immune defect
Severe disease presenting in neonates/infants, immunological emergency
What are the symptoms of immune deficiency?
Failure to thrive, skin problems, chronic chest problems, organomegaly/adenopathy
When should you investigate for immune deficiency?
Frequent/unusually severe infections, infection with unusual organisms, and family history
What tests should you do for immune deficiency?
FBC - low total WBC, neutrophil or lymphocytes
Total Ig GAM +/- E
Responses to routine immunisation
Lymphocyte subsets: numbers of T and B cells
Lymphocyte function
What is the treatment for immune deficiency?
Antibiotic/antiviral prophylaxis
Prompt treatment of infections
Replacement of immunoglobulin
Bone marrow transplant
What are the warning signs for primary immunodeficiency?
Most important family history
2 or more of
- 4 or more new ear infections within a year
- 2 or more serious sinus infections within a year
- 2 or more months on antibiotics with little effect
- 2 or more pneumonias within a year
- Failure of an infant to gain weight or grow normally
- Recurrent, deep skin or organ abscesses
- Persistent thrush in mouth or fungal infection on skin
- Need for IV antibiotics to clear infections
- 2 or more deep-seated infections including septicaemia
- A family history of primary immunodeficiency
How do vaccines work?
Induce immunity: T and B cells (antibody) specific for organisms/toxins
Induce immunological memory
Protein antigens stronger stimulation
Antibodies (B cell memory) easily measured
Specific T cell memory
Herd immunity
Name a live attenuated vaccine
MMR
BCG
Nasal flu
Rotavirus
Name an inactivated vaccine
Whole cell pertussis
Name an inactivated toxin
Diphtheria
Tetanus