micro 4 Flashcards
(40 cards)
corynebacterium diphtheria charcteristics
catalase positive club shaped rods gram positive palisade like immotile
corynebacterium diphtheria reservior
only humans
talk about diphtheria toxin
encoded by tox gene introduced into bacteria by lysogenic bacteriophage which is an exotoxin made of 2 subunits
A : has a catalytic region to inhibit elongation factor EF-2
B that has receptor binding and translocation
two main clinical presentations of diphtheria
respiratory and cutaneous
respiratory diphtheria
exaudative pharyngitis low grade fever and sore throat
pharyngeal exaudate is firmly adherent pseudomembrane in oropharynx after a week it gets dislodged and expectorated
bull neck
systemic spread of toxin causes myocarditis and neurotoxin
cutaneous diphtheria
papule that develops into chronic non healing ulcer
lab diagnosis of diphtheria
culture in tellurite contain media (HOYLE and TINSDALE )
toxigenicity test by ELEK or PCR for tox gene
most important treatment step for corynebacterium diphtheria
administration of antitoxin
antibiotic for corynebacterium diphtheria
penicillin and erythromycin
Bacillus anthracis charc and how is it acquired
gram positive , spore former
acquired by occupational exposure to herbivorous animals
main virulence factors of Bacillus anthracis
toxin component ;
PA , LF and EF
polypeptide capsule
role of each component of Bacillus anthracis toxin
PA ; cell binding and endocytosis
EF: increase camp
LF ; stimulate IL-1 and TNF alpha augment IR
ANTHRAX FORMS and charac
cutaneous (hide porters ) : commonest and least severe, 12 days after injury a pupule forms that then forms to blister then central necrosis and hemorrhage (BLACK ISCHAR) before falling
Gastrointes. : mucosal ulceration and mesentric LAP
inhalation ( wood sorter) : symp 2 months after spore entry (mediastinal infection and mediastinal LAP)
how is Bacillus anthracis diffrentiated from rest of Bacillus species
immotile
non hemolytic on sheep blood agar
medusa head
anthrax treated by
ciprofloxacin and doxycycline
bordetella pertussis charac
strict aerobic , gram - coccobacilli
does bordetella pertussis have any reservoir other than humans
no
pathogenicity of bordetella pertussis
attachment by protein adhesin ( pertactin , hemagglutinin) and fimbrie
tissue damage : dermonecrotic toxin (ischemia)
tracheal cytotoxin
systemic toxicity by pertussis toxin :
no control over adenylate cyclase cause increase in cAMP , hyperglycemia , lymphocytosis
bordetella pertussis incubation period
7-10 days
stages of bordetella pertussis clinical illness
- catarrhal (1-2 wks) : common cold , bacterial shedding is highest
- paroxysmal (2-4 wks) : whooping cough paroxsyms and lymphocystosis
- convalescent (3 wks) ; decreased paroxsymal intensity but complications ( pneumonia , seizures , encephalopathy)
how to detect bordetella pertussis on culture
on Bordet Gingou agar or regan lowe agar
what to do to decrease transmission and shorten disease course of bordetella pertussis
antibiotics within given 3 weeks of cough onset
first line of bordetella pertussis
macrolide ( azithromycin)
vaccine of bordetella pertussis
acellular pertussis toxoid vaccine (aP)
