Bordetella and Haemophilus

Question 1

H flu bacteriology

Answer 1

• small, gram neg, pleomorphic rod
• nonmotile
• non spore forming
• grows on lab media with X and V (heme and NAD)- extracts from RBCs- blood loving
• human restricted
• transmitted by respiratory droplets or direct contact
• encapsulated and unencapsulated forms

Question 2

h flu bacteriology 2

Answer 2

• high pathogenicity strains have capsule
• 6 serotypes with capsules, type B (Hib) is most severe and causes meningitis, pneumonia, septic arthritis
• Hib capsule of polyribosyl ribitol phosphate (PRP) is target of vaccine
• unencapsulated strains (NTHi) cause local mucosal infections, can spread if untreated, not covered by vaccine
• asymptomatic carrier of Hib is rare, NTHi cp,,pm

Question 3

Hib pathogenesis

Answer 3

• colonization facilitated by IgA protease- clears IgA from resp mucosa
• once established, invades blood
• magnitude and duration of bacteremia determine severity of illness**
• meningitis-unvax/untreated mortality is 90%
• 50% of survivors have neuro sequelae

Question 4

Hib pathogenesis 2

Answer 4

• host defense is complement and anti-capsule antibody
• vaccination against capsule blocks and reverses infection at early bacteremic stage
• most infections in kids 6 mo- 6years
• maternal antibody wanes, kids can’t raise response
• disease may recur until effective memory response (5yo)
• rare in patients over 6 unless immunocompromised

Question 5

NTHi pathogenesis

Answer 5

• lacks capsule, but still has pili, attachment proteins, IgA protease
• pneumonia with biofilm formation in CF patients
• pneumonia, septic arthritis after untreated mucosal infection
• neonatal sepsis, maternal sepsis after vaginal delivery if NTHi normal flora

Question 6

Hib meningitis exam

Answer 6

• rapid onset fever, AMS, HA, stiff neck
• may be lethal in hours in infants
• LP for CSF culture and gram stain
• CT for subdural effusion if not responsive to antibiotics

Question 7

Hib cellulitis exam

Answer 7

• raised, indurated, tender area on head or nec
• needle aspirate for culture and gram
• may affect eyes, CT if it does

Question 8

Hib otitis media, sinusitis exam

Answer 8

-pain and swelling, bulging tympanic membrane

Question 9

Hib epiglottitis exam

Answer 9

• swollen, cherry red epiglottis
• progressive respiratory difficulty
• inability to swallow
• lateral neck radiograph once airway is secured

Question 10

Hib septic arthritis

Answer 10

• single large, red, angry joint

- side note- can also cause sepsis, pneumonia, pericarditis

Question 11

NTHi exam in neonates

Answer 11

• biotype 4
• associated with premies, premature rupture of membranes, low birth weight, maternal chorioamniotis
• presentation within 24 hours of birth
• vertically acquired
• nonspecific symptoms- bacteremia, sepsis, meningitis, pneumonia, conjunctivitis, cellulitis

Question 12

NTHi exam post partum mom

Answer 12

• sepsis with endometritis, tubo-ovarian abscess, chronic salpingitis
• take laproscopic fluid samples for culture and gram

Question 13

NTHi complications from local infection

Answer 13

• begins with mucosal infection of ear, eye, sinuses, bronchioles
• may cause invasive disease similar to Hib in combination with predisposing conditions:
• advanced age, alcoholism, malignancy, CF, asthma

Question 14

H flu lab diagnosis

Answer 14

• gram stain and culture relevant body fluids
• culture on chocolate (heated-blood) agar with and without factors X and V
• growth only with factors usually suffices for diagnosis
• proceed with antimicrobial sensitivity testing
• bio/immuno tests for typying- immune tests for capsule will still be positive after antibiotics begin
• septic arthritis- elevated sed rate and CRP

Question 15

H flu CSF with meningitis

Answer 15

• neutrophils
• decreased glucose
• increased protein
• capsular antigen
• positive gram stain

Question 16

H flu meningitis treatment

Answer 16

• ceftriaxone (3rd gen!)
• meningitis in kids >2 mo- add dexamethasone
• may change as results of sensitivity tests come back
• ongoing supportive care even after

Question 17

H flu URI treatment

Answer 17

-amoxicillin/clavulanate or trimethprim/sulfamethoxazole

Question 18

h flu treatment for cellulitis, pericarditis, septic arthritis

Answer 18

• surgical drainage in addition to choice of:

- Bactrim, cefuroxime axetil, cefisime, clarithromycin, azithromycin, fluoroquinolones

Question 19

H flu epiglottitis treatment

Answer 19

-intubation, same antibiotics

Question 20

h flu otitis media treatment

Answer 20

-amoxicillin

Question 21

H flu prevention

Answer 21

• vaccine!
• capsular polysaccharide of type B conjugated to diptheria toxoid or other carrier protein
• routine inoculation for 2-15 mo olds in US
• incidence is down 99% in vaccinated areas
• Hib meningitis is almost gone in US and Canada
• close contacts of an invasive disease patient receive prophylactic rifampin

Question 22

B pertussis bacteriology

Answer 22

• small encapsulated gram negative rod
• human restricted
• transmitted by respiratory droplets
• causes whooping cough, primarily in infants <2 years exposed by their mothers, ~4% unvaccinated fatality
• highly contagious, 80-90% of exposed develop symptoms, must isolate if admitted

Question 23

b pertussis bacteriology 2

Answer 23

• incidence and mortality fell 99% after introduction of vaccine in 1930s
• both have been rising since 1976, now appearing in adolescents and adults
• combination of surprisingly high need for boosters and vaccine refusers
• may be seen locally in infants too young to have finished course of vaccination
• B parapertussis is related, symptoms similar but milder

Question 24

B pertussis pathogenesis

Answer 24

• filamentous hemagglutinin pilus attaches bacteria to cilia of epithelial cells lining respiratory tract (target of aceullular vaccine)
• growing cells release:
• pertussis toxin, an AB subunit ADP ribosylator
• kills ciliated cells- less resistance to bacterial growth, cough (more droplets)
• inhibits chemokine signal transduction- lymphocytosis **
• tracheal cytotoxin- also kills ciliated cells

Question 25

B pertussis pathogenesis 2

Answer 25

- damaged cells and growing bacteria produce a mucopurulosanguineous exudate in the resp tract that compromises small airways - combines for paroxysmal cough that spreads more droplets - bacteremia is not a thing here - prognosis is good, complications minimal, if patient >6mo without complicating comorbidity (premie, cardiac, pilm, neuromuscular, neurologic disease) - in infants, pneumonia and oxygen deprivation complicate

Question 26

B pertussis exam

Answer 26

- patients are often afebrile but dehydrated - acute tracheobronchitis developing into severe paroxysmal cough - history of: - incomplete or absent vax - premie - underlying disease - asthma - obesity - pregnancy

Question 27

stage 1 of pertussis

Answer 27

- catarrhal - nonspecific URI symptoms - congestion - sneezing - rhinorrhea - maximally contagious

Question 28

stage 2 of pertussis

Answer 28

- paroxysmal - intense coughing - series of hacking coughs - copious mucous production - inspiratory whoop as air rushes past narrowed glottis - CNS anoxia and exhaustion may appear but are not lethal - infants turn blue, children may turn red and vomit

Question 29

stage 3 of pertussis

Answer 29

- convalescence | - fatigue and chronic cough

Question 30

pertussis exam in adults

Answer 30

- whoop may be absent - primary symptom is extremely prolonged URI with coughing - 100 day cough - secondary pneumonia may be lethal

Question 31

pertussis diagnosis on lab

Answer 31

- infants and kids show pronounced leukocytosis, up to 70% leukocytes - fastidious- can culture organism from nasopharyngeal swabs or aspirate on Bordet-Genhou agar during stage 1 or 2, grows very slowly, and may be negative if vax or on antibiotics - patient samples or cultures may be tested with specific antibodies, not rec because of low sens and sp - PCR and ELISA good but not universally available or standardized - adults with prolonged cough may have neg results

Question 32

b pertussis treatment

Answer 32

- macrolides prevent the disease from progressing and transmitting but do not spontaneously heal the respiratory lining - supportive care is required, observation of symptoms and assistance as needed - infants and some children will need to be admitted for supplemental oxygen and mucous suctioning with monitoring of heart and resp rate and oxygen levels during paroxysmal stage, droplet precautions will be needed for 5 days - steroids and albuterol have been used to control cough, but no studies have been performed on safety/efficacy of either

Question 33

B pertussis prevention

Answer 33

- acellular vaccine- genetically inactivated toxoid, filamentous hemagglutinin, pertactin, fimbriae types 2 and 3 - raises protective response very safely, used in US, being investigated for use in newborns - vax fam to prevent infant cases - booster for 12 year olds - DTaP and Tdap killed vaccine: whole heat killed bacterium. longer protection, but pain and fever on vax -linked to small risk of encephalopathy, used outside US -prophylactic erythromycin given to all exposed unimmunized and exposed small children regardless of vaccine status