Bordetellae & Mycolasmae Flashcards
Bordatellae genus
- Gram -
- coccobacilli
- obligate aerobe
- fastidious
- B. pertussis
- B. parapertussis
- B. bronchseptica
B. pertussis
- Encapsulated coccobacillus
- Motile (due to flagella)
- Slow growing on special selective medium
B. pertussis Virulence Factors
- Pertussis toxin
- Adenylate cyclase toxin
- Tracheal cytotoxin
- Pertactin
- Fimbria
- Filamentous hemagluttinin
B. pertussis Epidemiology
- Strict human pathogen
- Highly contagious
- Classically toddlers & young children
– Now >70% of deaths < 1 year
• Partially immune adolescents & adults are primary reservoir
– Milder symptoms mask disease
– “Just a cold”
•Resurgence in last 2 decades
B. pertussis Pathogenesis: Attachment
• Primarily cilia of bronchial epithelium:
-Pili, fimbriae, filamentous hemagglutinin
B. pertussis Pathogenesis: Virulence Factor Production
- Pertussis Toxin
- Adenylate cyclase
- Tracheal cytotoxin
B. pertussis Pathogenesis: Alteration of Host Cell Dynamics
- Ciliary dysfunction
- Non-ciliary impacts
B. pertussis Pertussis Toxin
B. pertussis Pertussis Toxin Effects
B. pertussis Adeylate Cyclase
B. pertussis Tracheal Cytotoxin
Bordetella Virulence Gene Regulation
- Expression is modulated in a two-component system by changes in specific environmental parameters, including temperature.
- The induction of virulence factors in B. pertussis is sequential, with adhesin expression (FHA and pili) preceding expression of factors involved in tissue injury (PT, AC).
- Multiple virulence genes respond to temperature and ionic changes.
B. pertussis Clinical Aspects
- 7-10 days incubation
- 3 Stages
- catarrhal
- paroxysmal
- convalescent
B. pertussis Catarrhal Stage
•In the catarrhal stage, the primary feature is a profuse, mucoid rhinorrhea, which persists for 1 to 2 weeks. The disease is most communicable at this stage, because large numbers of organisms are present in the nasopharynx and the mucoid secretions
B. pertussis Paroxysmal Stage
- The appearance of a persistent cough marks the transition from the catarrhal to the paroxysmal coughing stage. At this time, episodes of paroxysmal coughing occur up to 50 times a day for 2 to 4 weeks. The characteristic inspiratory whoop follows a series of coughs as air is rapidly drawn through the narrowed glottis.
- Vomiting frequently follows the whoop. Apnea may follow such episodes, particularly in infants. Marked lymphocytosis reaches its peak at this time, with absolute lymphocyte counts of up to 40,000/mm3
B. pertussis Convalescent Stage
•During the 3- to 4-week convalescent stage, the frequency and severity of paroxysmal coughing and other features of the disease gradually fade.
B. pertussis Complications
- The most common complication of pertussis is pneumonia caused by a superinfecting organism such as Streptococcus pneumoniae.
- Atelectasis is also common but may be recognized only by radiologic examination.
- Other complications are related to the venous pressure effects of the paroxysmal coughing and the anoxia produced by inadequate ventilation and apneic spells.
B. pertussis Diagnosis
B. pertussis Treatment
- Antimicrobial agents have little effect once coughing stage is reached (damage is done)
- Erythromycin in prodromal or catarrhal stage
B. pertussis Prevention
- Chemoprophylaxis – erythromycin for close contacts
- Immunization
- DTap for ypung children
- TDap for adults
Mycoplasma genus
- small, no cell wall
- M. pneumoniae
- M. genitalium
- M. ureaplasma
M. pneumoniae pneumonia
•Respiratory symptoms mild enough to function, but usually not severe enough for hospitalization
-Pharyngitis, sinus congestion, incubation period up to 3 weeks
M. pneumoniae pneumonia Diagnosis
- Culture: Eaton’s agar or similar complex medium; 7-12 days; “fried-egg” colonies
- Serology
- PCR
M. pneumoniae pneumonia Treatment
• Macrolides, Doxycycline
M. genitalium
