Diphtheria. Differential diagnosis in patients with sore throat. Flashcards
what is the ETIOLOGY OF DIPHTHERIA ?
corynebacterium diphtheria
what are the CHARACTERISTICS OF CORYNEBACTERIUM DIPHTHERIA ?
gram positive
non sporulating
club shaped
bacillus
contains METOCHROMATIC GRANULES - stains red with blue dye
contains toxigenic and non toxigenic strains
EPIDEMIOLOGY OF CORYNEBACTERIUM DIPHTHERIA ?
occurs in patients 20 years of age or older
cutaneous diphtheria - usually seen in tropical regions
only reservoir are humans
peak during winter
what is the ROUTE OF INFECTION IN CORYNEBACTERIUM DIPHTHERIA ?
air-droplet
what is the PATHOGENESIS OF CORYNEBACTERIUM DIPHTHERIA ?
enters through resp droplets
colonizes the resp tract - resp diphtheria and less commonly
pre existing sin lesions - cutaneous diphtheria
toxigenic stains - ENCODES EXOTOXIN - DIPHTHERIA TOXIN - Diphtheria toxin is a heat-labile protein - destruction of the resp epithelium
deposition of necrotic epithelium with fibrinosuppurative exudate - causing a pseudomembrane over the pharynx , tonsils
edema of cervical lymph node and soft tissue - bull neck appearance - airway obstruction
systemic effects of toxins
fatty change and myocardial necrosis
nerve demyelination
what is the INCUBATION OF PERIOD COR CORYNEBACTERIUM DIPHTHERIA ?
in unionised - 4-14 days
resp diphtheria - 2-5 days
what are the CLINICAL MANIFESTATIONS OF C DIPHTHERIA ?
local - early stage
anterioir nasal diphtheria - bloody rhinorrhea
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tonislar and pharyngeal diphtheria
begins with sore throat
low grade fever
greyish white pseudomembrane of posterioir pharyngeal wall or the tonsils
- attempt to scrape the pseudomembrane exposes the underlying capillaries and causes heavy bleeding
this can be local or distributed along the tracheobronchial tress
= this membrane is very infectious
bull neck - cervical lymphadenopathy and swelling of soft tissue - airway obstruction - dyspnea
foul mouth odour
laryngeal dipheria - dyspnea , inspiratory stridor , hoarseness of voice
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systemic features due to dissemination of toxin -
cardiac - myocarditis -2/3rd patients arrhythmia congestive heart failure circulatory collapse galloping
reversible polyneuropathy -
Dysphagia and nasal dysarthria, facial and tongue numbness
-> cranial neuropathies causing oculomotor and ciliary paralysis
acute tubular necrosis - due to direct toxin effect or hypotension
adrenal insufficiency
septic arthritis
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diphtheria in eye - acute conjunctivitis
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diphtheria of ear - external auditory channel
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genital diphtheria
vulvovaginitis edema and tenderness
what are the CLINICAL MANIFESTATION OF CUTANEOUS DIPHTHERIA ?
scaly erythematous rash
impetigo
deep punched out ulcers - with necrotic sloughing or pseudomembrane formation
-no systemic effects
what is the DIAGNOSIS OF C DIPHTHERIA ?
pharyngeal swabs and culture -
microscopy - clustered in angular arrangements
culture media - cysteine tellurite agar - appear as black colonies
loftier medium - metachromatic granules
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identify the strain after culture confirms corynebacterium dptheria
elek test - c diphtheria grown in culture with antitoxin impregnanted filter paper - positive if strain toxigenic
or PCR to identify of the virus has the toxins gene
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myocarditis test - ECG and - ST-T wave changes , first degree heart block
cardiac markers - serum troponin 1
what is the TREATMNET OF C DIPHTHERIA ?
therapy should start immediately upon clinical suspicion - even before diagnostic confirmation !
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patient isolated as soon as possible
IM penicillin G then oral penicillin V when swallowing is possible for 14 days
or oral/iv ERYTHROMYCIN FOR 14 DAYS
immediate administration of diphtheria antitoxin - only neutralise the unbound toxin - therefore administered early int he course of the disease
but immediate- type - hypersensitivity must be ruled out -> they
would require desensitization before receiving antitoxin
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airway support
what is the PREVENTION OF C DIPHTHERIA ?
pre exposure
toxoid vaccine - formalin inactive toxin
4 forms of toxoid - DTap , Tdap , DT , Td
- diphtheria toxoid vaccine co administered with tetanus vaccine
DTaP (full-level DIPHTHERIA TOXOID, TETANUS TOXOID, and acellular
pertussis vaccine) is currently recommended for children up to the
age of 6
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Tdap is recommended for adolescents and adults
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immunization: 2, 4, 6, 15-18 moths and 4-6 years
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reimmunization: 11-12, 19 years and older, and a booster every 10
dd os diphtheria ?
faucial mononucleosis, streptococcal or viral pharyngitis and tonsillitis, Vincent’s angina, scarlet fever, and acute epiglottitis - toxin-producing C. ulcerans can cause typical respiratory diphtheria, requiring the same treatment
