Infectious Diseases Flashcards
What is sepsis?
SIRS +suspected or proven infection
What is severe sepsis and what is septic shock?
Severe sepsis=sepsis + organ dysfunction
Septic shock=sepsis + CVS dysfunction
What >2 of categories is needed for SIRS to be present?
- Temp
- WCC
- Tachycardia
- Tachypnoea
Why should you not focus too much on looking for hypotension in paediatrics when it comes to sepsis?
Incredibly late sign in children and only drop BP when in decompensated shock
Why do we worry specifically about infants <3 months in age?
- Increased risk of bacterial infection, sepsis, meningitis
- May have minimal signs and symptoms
- Presentation often non-specific
- May not mount a febrile response
- Deteriorate quickly
What risk factors would make you think of infection in an infant <3 months?
- Prematurity (<37/40)
- PROM
- Maternal pyrexia/chorioamnionitis
- Maternal GBS or previous child with GBS
- Maternal STI
What is the management of sepsis?
ABC (C=fluid bolus (20ml/kg 0.9%NaCl)
DEFG (Don’t ever forget Glc)=2ml/kg 10% dextrose
Abx:
- 3rd generation cephalosporin (e.g. Cefotaxime/Ceftriaxone)
- Add IV amoxicillin if <1month old (Listeria not covered - most common cause of sepsis meningitis in this age)
What bloods are done in sepsis?
FBC (leukocytosis, thrombocytopaenia)
CRP
Coagulation screen (DIC)
Blood gas (metabolic acidosis, raised lactate)-capillary or venous
Glc
Blood culture
What cultures are taken in sepsis?
Blood
Urine
CSF (including send to virology)
+/-stool (micro + virology)
If a child is presenting with sepsis with an unclear source what can a CXR be helpful for excluding?
Focal Pneumonia
What different organisms are responsible for sepsis in neonates <1 month compared to older infants & children?
Neonates:
- Group B strep
- E.coli
- Listeria monocytogenes
Older infants & children:
- Strep pneumoniae
- Neisseria meningitidis
- Group A strep
- Staph aureus
If any child <3 months with … unless its immediately post immunisation paediatricians want to see them
FEVER
What is meningitis and what is meningism?
Meningitis=A disease caused by inflam of the meninges
Meningism=The clinical signs & symptoms suggestive of meningeal irritation
Where does CSF lie?
Between arachnoid and pia mater
What is apnoea?
Pause in breathing lasting for >20 secs-unique to young infants
Sign of significant respiratory distress and reduced resp drive
What are the clinical signs of meningitis?
- Nuchal rigidity (Neck stiffness)=Palpable resistance to neck flexion
- Brudzinski’s sign=Hips and knees flex on passive flexion of the neck
- Kernig’s sign=Pain on passive extension of the knee
What are the causes of childhood meningitis?
- Bacterial
- Viral (mainly enterovirus)
- Fungal-neonates/immunocompromised
- Unknown/aseptic
What are the organisms cause bacterial meningitis?
Neonates (<1month)
- Group B strep
- E.coli
- Listeria
Older infants and children
- Strep pneumoniae
- Neisseria meningitidis
- Hemophilus influenzae type B (HiB)
How is H. Influenza carried and what is the type should be worried about?
Nasopharyngeal carriage
Small, non motile, gram -ve coccobacillus
Encapsulated H. influenza
(Non encapsulated=non typable H.influenzae (NTHI)-otitis media & sinusitis-rare for it to cause invasive infection)
Neisseria meningitidis is a gram -ve diplococcus in which humans are its only natural hosts. How is it transmitted?
Nasopharyngeal carriage
- Transmission via resp secretions
- Infection often follows viral URTI
- Polysaccharide capsule
Endotoxin (LPS)-big driver of the sepsis response
What are the risk factors for invasive meningococcal disease?
- Age <1 year or 15-24 years
- Unimmunised
- Crowded living conditions
- Household or kissing contact
- Cigarette smoking (active or passive)
- Recent viral/Mycoplasma infection
- Complement deficiency
Invasive meningococcal disease is rapidly progressive, what are some significant long term sequelae associated with it?
Amputation
Scarring
Hearing loss
Cognitive impairment/epilepsy
Streptococcus pneumoniae (Pneumococcus)-Gram +ve lancet shaped diplococcus, facultative anaerobe, polysaccharide capsule: where dose it colonise?
Colonises nasopharynx
Preceding URTI RF for invasive infection
Resp droplet transmission
What are the risk factors for invasive pneumococcal disease?
Age <2 years
Cigarette smoking (active or passive)
Recent viral URTI
Attendance at childcare
Cochlear implant
Sickle cell disease
Asplenia
HIV infection
Nephrotic syndrome
Immunodeficiency/Immunosuppression
What are the common neurological sequelae of pneumococcal meningitis?
- Hydrocephalus
- Neurodisability
- Seizures
- Hearing loss
- Blindness
What is the treatment of meningitis?
SAME TX AS SEPSIS!!!!
ABC
DEFG
Abx
What bloods should be done for meningitis?
FBC (leukocytosis, thrombocytopaenia)
U&Es, LFTs
CRP
Coagulation screen (DIC)
Blood gas (metabolic acidosis, raised lactate)
Glucose
Blood culture
Meningococcal/Pneumococcal PCR
LP is essential in meningitis when should it ideally be done?
Ideally prior to Abx but do not delay Abx if LP cannot be performed
When should you definitely not do a LP?
When there are signs of raised ICP
What should you request on an LP?
Microscopy
Gram Stain
Culture
Protein
Glucose
Viral PCR
What are the findings on LP of a bacterial meningitis?
- Turbid or purulent
- High opening pressure
- WCC increased (polymorphs)
- High protein
- Reduced Glc (<50% serum)-should do a blood sugar at the same time as doing LP
Are different organisms that cause bacterial meningitis treated for different durations?
They are indeedy
Majority of skin & soft tissue conditions are caused by what and what can both these organisms cause?
Staph (mainly S. aureus) or Strep (S. pyogenes)
Both organisms cause osteoarticular infection, bacteraemia, toxin-mediated diseases (Staphylococcal & Streptococcal Toxic Shock Syndrome (TSS))
Can be difficult to distinguish clinically
Is resistance a problem in Strep pyogenes?
Strep is universally S to penicillin
Strep is B haemolytic and has oropharyngeal carriage whereas staph aureus is?
Coagulase +ve and colonises skin and mucosa
How does staphylococcal scalded skin syndrome present?
- Usually <5yo
- Toxin mediated (exfoliatoxin)
- Initial bullous lesions
- Followed by widespread desquamation
- Mild fever
- Purulent conjunctivitis
What sign is indicated in staphylococcal scalded skin syndrome and how is the condition managed?
Nikolsky sign (rub over skin-sloughs off, desquamates under minimal pressure)
Mx=IV Flucloxacillin + IV fluids
What are the characteristics of scarlet fever (scarlatina)?
- 2-5 day incubation period
- Fever, malaise, sore throat
- STRAWBERRY TONGUE
- SANDPAPER RASH
- Skin peeling (desquamation)
How is scarlet fever managed?
Notifiable disease- inform public health
Phenoxymethylpenicillin (Penicillin V) 10 days
- Reduces duration and severity illness by ~1 day
- Reduces incidence of complications (quincy/acute rheumatic fever/post-streptococcal glomerulonephritis)
- Reduces transmission
What are the potential complications of scarlet fever?
Abscess formation -
retropharyngeal or peritonsillar (quincy)
Acute Rheumatic Fever
- most common cause acquired heart disease in children worldwide
- 2-3/52 after pharyngitis
- arthritis, carditis, chorea, erythema marginatum, subcutaneous nodules
Post-streptococcal glomerulonephritis
What is toxic shock syndrome (TSS) and what can it result in?
Acute febrile illness caused by Gram +ve bacteria (S. aureus & GAS) rapidly progressing to shock and multiorgan failure
Superantigen causes intense T cell stimulation
excessive immune activation
pro-inflammatory cytokine release (TNF-α, IL-1, IL-2, IFN-γ)
Case fatality
30-60% GAS
3-6% S. aureus
What are the clinical features of TSS?
Fever
Diffuse, maculopapular, ‘sunburn’ rash
Mucosal changes
- non-purulent conjunctivitis
- swollen lips
- strawberry tongue
Profuse diarrhoea (S. aureus)
Rapid progression to shock & multi-organ failure
- tachycardia
- prolonged CRT
- hypotension
- renal impairment
- transaminitis
- reduced GCS
How is TSS managed?
ABC
Fluid resuscitation +/- inotropes
Cultures
- Blood
- Throat swabs
- Wounds
IV Antibiotics
Flucloxacillin + Clindamycin
IVIG
Avoid NSAIDs (increases risk of necrotising fasciitis)
Surgical debridement
Staph and strep cause very similar patterns of infection except in what?
Except Scarlet Fever (exclusively GAS) & SSSS
Toxins are major … factors of staph and strep
VIRULENCE
What organism is scarlet fever unique to?
GROUP A STREP (GAS)
What are the predominant causes of skin & soft tissue infection?
Staph & strep infections
