Haemophilus and Bordetella Flashcards
What is the gram stain for H. influenzae?
Gram (-) pleomorphic rod
What are the two things needed to grow H. influenzae on lab media?
Factors X (heme) and V (NAD)
How is H. influenzae transmitted?
By respiratory droplets or direct contact
What do the high-pathogenicity strains of H. influenzae have?
polysaccharid capsule
What serotypes of the capsule types causes the most severe disease?
Type B (Hib)–causes meningitis, pneumonia, spetic arthritis
What is the target for the H. influenzae vaccine?
Hib capsule of polyribosyl ribitol phosphate (PRP)
What is the unencapsulated strain of H. influenzae called and what does it cause?
NTHi–may cause local mucosal infections, can spread if untreated, and is NOT covered by the vaccine
What does the Hib serotype of the H. influenzae have in order to colonize the respiratory epithelium?
IgA protease–clears IgA from respiratory mucosa
What are the possible outcomes when pts develop meningitis from H. influenzae?
unvaccinated untreated mortality–90%
50% of survivors have neurological sequalae–deafness, developmental delay
What can the NTHi strain of the H. influenzae causes –the unencapsulated strain?
Pneumonia with biofilm formation in CF pts
Pneumonia, septic arthritis after untreated mucosal infection
Neonatal sepsis, maternal sepsis after vaginal delivery if NTHi is normal flora
What are the major complications caused by Hib strain of H. influenzae?
Meningitis–rapid onset
Cellulitis–usually on head or neck–may affect eyes
Otitis media, sinusitis–pain and swelling tympanic membrane
Epiglottitis–swollen cherry-red epiglottis, progressive respiratory difficulty
Septic arthritis–single large joints
What are the complications of NTHi–biotype 4?
Neonates–associated with prematurity, premature rupture of membranes, low birth weight, maternal chorioamniotis
-vertically acquired
Postpartum–sepsis with endometritis, turbo-ovarian abscess, chronic salpingitis
What is the tx for meningitis caused by H. influenzae?
Ceftriaxone
Meningitis in children >2 mo: add dexamethasone
What is the tx of upper-respiratory infection caused by H. influenzae?
Amoxicillin+clavulanate
OR
Trimethoprim+sulfamethoxazole
What its the tx for cellulitis, pericarditis, and septic arthritis caused by H. influenzae?
Surgical drainage in addition to:
Trimethoprim-sulfamethoxazole, cefuroxime axetil, cefixime, clarithromycin, azithromycin, or fluoroquinolones
What is the tx for otitis media caused by H. influenzae?
Amoxicillin
What type of vaccine is given for H. influenzae?
Capsular polysaccharide of type B conjugated to diphtheria toxoid or other carrier protein (Hib)
What is the gram stain of B. Pertussis?
Gram (-) rod
How is B. pertussis transmitted?
Respiratory droplets
What does B. pertussis cause?
Whooping cough–primarily in infants
What is related to the B. pertussis infection but has milder syms?
B. parapertussis
What attaches B. pertussis to cilia of epithelial cells lining the respiratory tract?
Filamentous hemagglutinin pilus
What does the pertussis toxin, an A-B subunit ADP-ribosylator cause?
Secondary attachment factor
Ciliostasis –kills ciliated cells–> less resistance to bacterial growth, cough
Inhibits chemokine signal transduction–Lymphocytosis
What does the tracheal cytotoxin from B. pertussis cause?
kills ciliated cells-ciliostasis
B. pertussis causes damaged cells and then the bacteria grows and produces what?
Mucopurulosanguineous exudate–compromises small airways
What are the risk factors for the development of an infection from B. pertussis?
Incomplete or absent vaccination Prematurity Underlying cardiac, pulmonary, neuromuscular, neurologic dz Asthma Obesity Pregnancy
What are the 3 stages of B. pertussis infection?
Stage 1: catarrhal–2 wks
Stage 2: Paroxysmal–2wks
Stage 3: Convalescence–2 months
What occurs during the 1st stage of B. pertussis infection?
Catarrhal stage 2 wks:
Nonspecific upper respiratory syms–congestion, sneezing, rhinorrea
Maximally contagious
What occurs during the 2nd stage of B. pertussis infection?
Paroxysmal stage 2 wks:
Intense coughing
–characteristic pattern–Series of hacking coughs, copious mucus production, inspiratory “whoop” as air rushes in past narrowed glottis
Infants turn blue
Children may turn red and vomit
What occurs during stage 3 of B. pertussis infection?
Convalescence stage 2 months:
Fatigue and chronic cough
What is seen when adults get B. pertussis infection?
Primary symtom is extremely prolonged upper respiratory infection with 110-day cough
Whoop and leukocytosis absent
What is seen on the bloodwork of children who have the B. pertussis infection?
Pronounced leukocytosis
What are the agar used to grow fastidious B. pertussis?
Regan-Lowe or Bordet-Gengou agar
May be negative if pt is immunized or already on antibiotics
What is given to prevent B. pertussis from progressing and transmitting?
Macrolides
What are the 2 vaccines available for B. pertussis?
Acellular vaccine–inactivated toxoid
Killed vaccine–whole heat-killed bacterium –> much longer-lived protection, but more pain and fever on vaccination – used outside US
What should be used for prophylactics if unimmunized pts are exposed to B. pertussis?
Erythromycin
What is needed every 10yrs for the B. pertussis vaccine to be effective?
Booster
