Bacterial, fungal and protozoal infections in childhood Flashcards by Costanza Coronelli

Bacteria (prokaryotes)

0.2-2 micro M diameter
Single, circular chromosome
No nucleus
No organelles
Divide by binary fission

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Fungi, Protozoa (eukaryotes)

10-100 micro M diameter
Multiple, linear chromosomes
Membrane-bound nucleus
Membrane-bound organelles
Divide by mitosis

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Bacterial toxins- Exotoxins

Proteins secreted by pathogen

e.g. cholera diarrhoea

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Diphtheria

Corynebacterium diphtheriae
Sore throat
Fever

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Diphtheria toxin

Diphtheria toxin (A+B subunits)
–> inhibits protein synthesis
Heart- myocarditis, heart block
Nerves- difficulty swallowing, paralysis, diplopia

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Bacterial toxins- Endotoxin

Part of outer membrane of Gram-negative bacteria
Released during lysis of organism
Lead to macrophage activation

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Pathogenesis of Meningococcal Septicaemia

Activation of inflammatory cascade via LPS
IL-6 and TNF-alpha
Myocardial depression
Coagulopathy
Endothelial dysfunction –> capillary leak and shock

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Children differences to adults

Immunological- immaturity, lack of memory
Anatomical- thinner skin, shorter airways, anatomy of Eustachian tube –> otitis media
Exposure- hygiene, nursery/day-care

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Fever

Temp > 37.8
Mouth- 0.5 less than rectal temp
Armpit- 1 degree less than rectal temp
Ear- similar to rectal core temp

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Severe bacterial illnesses

Septicaemia
Meningitis
Pneumonia
Epiglottitis
Septic arthritis
Osteomyelitis
TB
Tetanus

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Common bacterial illnesses

Tonsillitis
Otitis media
UTI
Gastroenteritis
Impetigo

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Organisms that cause septicaemia + meningitis

Streptococcus pneumoniae
Neisseria meningitidis (group B + C, increase in group W in students)
Haemophilus influenzae B (HiB)

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Recognising septicaemia

Tachycardia
Tachypnoea
Prolonged capillary refill
Low BP (late sign)
Rash

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Clinical presentation meningitis

Not able to tolerate bright lights
Drowsy
Stiff neck

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Meningitis diagnosis

CSF- lumbar puncture

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CSF changes in meningitis- Bacterial

Cloudy
polys +++
Protein 0.2-1
<60% of blood glucose

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CSF changes in meningitis- Viral

Clear CSF
lymphs ++
Protein 0.15-0.45
Normal glucose

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CSF changes in meningitis- TB

Opalescent
lymphs ++
Protein 0.3-2
<60% of blood glucose

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Top 3 organisms in young infants

Group B Strep
E. Coli
Listeria

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Older children antibiotic

Ceftriaxone

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Young infant antibiotic (<3 months)

Cefotaxime or ceftriaxone

Amoxicillin also needed for listeria cover

Neonatal Sepsis

Maternal colonization with pathogens- colon, vaginal canal
Early onset- within 48 hours
Late onset- meningitis, bones and joints

Gram-positive Cocci

Staphylococcus
Streptococcus
Enterococcus

Gram-positive Bacilli

Corynebacterium
Listeria
Bacillus- cereus, anthracis
Clostridium- tetani, botulinum, difficile

Streptococcus Pneumoniae

Gram positive Normal flora in 5-70% people Diplococci

Immune defects predisposing to pneumococcal infection

Absent/non-functional spleen Hypogammaglobulinaemia HIV infection

Splenectomy

Vulnerable to encapsulated bacteria- Pneumococcus, HiB, Meningococcus Vaccination Lifelong penicillin daily

Non-invasive disease

Acute otitis media Sinusitis Conjunctivitis Pneumonia

Invasive disease

``` Septicaemia Meningitis Peritonitis Arthritis Osteomyelitis ```

Empyema management

Chest drain +/- urokinase | Video assisted thoracoscopic surgery

Pneumococcus vaccination

Pneumococcal polysaccharide vaccine - pneumovax (23 serotypes) Pneumococcal conjugate vaccine- prevenar (13 serotypes)

Tetanus

Gram positive bacillus Spores found in soil Tetanus toxin (exotoxin)- interacts with NMJ

Tetanus infection causes

Lack of maternal vaccination in pregnancy Use of unclean blade to cut cord Application of mud or dung to cord

Tetanus symptoms

``` Weak Lethargic Poor suck Spasms Fits ```

Fungi classification

>100,00 named species <500 cause disease Yeasts Moulds

Yeasts

e.g. Candida Unicellular, oval or round Asexual budding

Moulds

e.g. Aspergillus Filamentous fungi Branching filaments (hyphae)

Fungal disease in children

Superficial Mycoses- common, normal hosts | Invasive mycoses- rare, opportunistic infections in immunocompromised hosts

Superficial mycoses

Candidiasis- nappy rash, treat with topical antifungal e.g. Nystatin Tinea corporis- ring worm, treat with topical antifungal

Invasive mycoses

Candidaemia- Extremely preterm infant, can affect kidneys and brain, long course of IV antifungal Pulmonary aspergillosis- Child with chronic granulomatous disease

Defects in neutrophils

Low neutrophil count (neutropenia) | Impaired neutrophil function (e.g. chronic granulomatous disease)

Defects in T cells

Congenital (e.g. SCID) | Acquired (e.g. HIV infection)

Classification Protozoa

Sporozoa Amoebae Flagellates

Sporozoa

``` Plasmodium species (malaria) Toxoplasma gondii (toxoplasmosis) Cryptosporidium (diarrhoea) ```

Amoebae

Entamoeba histolytica (amoebic dysentery)

Flagellates

Giardia (diarrhoea, malabsorption) Trypanasoma (sleep sickness, Chagas) Leishmania

Malaria 4 main species

P. Falciparum- most severe, cerebral malaria P. vivax P. ovale P. malariae

Malaria in children

Can be non-specific- fever, lethargy, vomiting, diarrhoea | Severe disease- anaemia, resp. distress, cerebral malaria, hypoglycaemia

Malaria treatments

Artemisinin derivatives Combination treatment More rapid reduction in parasitaemia

Congenital toxoplasmosis

``` Toxoplasma gondii Sporozoa Oocysts excreted by cats pregnant women infected Multiply in pregnant women ```