Haemophilus and Bordatella Flashcards
H. influenzae bacteriology
small gram (-) pleomorphic rod. nonmotile. non spore forming. grows on lab media only with additions of factors X and V (blood loving bacteria). human restricted. transmitted by droplets or direct contact. 6 serotypes, type B is worst (Hib). can be encapsulated or unencapsulated (NTHi)
H. influenzae pathogenesis (Hib)
colonization facilitated by IgA protease. invades bloodstream. meningitis. neurological sequelae (deafness, developmental problems). host defense by complement and anti-capsule antibody. most infections in children 6mo-6yr, usually 6mo-1yr.
NTHi pathogenesis
lacks capsule needed for high pathogenicity, still has pili, attachment proteins, and IgA protease. pneumonia with biofilm in CF patients. pneumonia and septic arthritis after untreated mucosal infection. neonatal sepsis and maternal sepsis after vaginal delivery
Hib exam
meningitis. cellulitis (may effect eyes). otitis media, sinusitis (bulging tympanic membrane). epiglottitis. septic arthritis (of single large joints). history: vaccine? recent URI?
NTHi exam
in neonates: associated with prematurity, low birth weight. presents within 24hr of birth. vertically acquired. nonspecific symptoms (bacteremia, sepsis, meningitis, pneumonia, cellulitis, conjunctivitis).
Postpartum: sepsis with endometritis, tubo-ovarian abscess, chronic salpingitis, take fluid for gram and culture
untreated local infection: mucosal infection, may cause invasive disease similar to Hib if predisposed: alcoholism, old, malignancy, CF, asthma
H. influenzae lab
gram stain and culture. culture on blood agar with and without factors X and V. serotype by quellung. do antimicrobial sensitivity testing. tests available for typing. septic arthritis: increased erythrocyte sed rates and C reactive proteins. meningitis: CSF contains neutrophils, low glucose, increased protein, capsular antigen. gram (+) if not on antibiotics yet
H. influenzae treatment
meningitis: ceftriaxone. in kids, dexamethasone.
URI: amoxicillin + clavulanate, or trimetho + sulfametho
Cellulitis, pericarditis, septic arthritis: drainage and trimeth-sulfameth, cefuroxime, etc.
Epiglottitis: maintain airway, same antibiotics as above.
otitis media: amoxicillin
H. influenzae prevention
vaccine. capsular polysaccharide of type B conjugated to diphtheria toxoid. routine for kids 2-15mo in US.
B. pertussis bacteriology
small encapsulated gram (-) rod. human restricted. transmitted by respiratory droplets. whooping cough. highly contagious
B. pertussis pathogenesis
filamentous hemagglutinin pilus attaches bacteria to cilia of epithelial cells lining respiratory tract. growing cells release pertussis toxin, an ADP-ribosylator which kills ciliated cells and causes lymphocytosis. tracheal cyttotoxin also kills ciliated cells. damaged cells make a mucopurulosanguineous exudate which compromises small airways, causing cough. no bacteremia! good prognosis
b. pertussis exam
afebrile but dehydrated. acute tracheobronchitis turns into severe paroxysmal cough. history of incomplete or absent vaccine, prematurity, underlying disease, asthma, obesity, pregnancy
3 stages of symptoms of b. pertussis
1: 2 weeks: Catarrhal: nonspecific upper respiratory symptoms: congestion, sneezing, runny nose. max contagion
2: 2 weeks: paroxysmal coughing. inspiratory whoop as air goes past narrow glottis. infants turn blue, children turn red and barf
3: 2 months: convalescence: fatigue and chronic cough
b. pertussis exam
in adults: whoop may be absent. leukocytosis may be absent. primary symptom is prolonged URI with cough.
b. pertussis lab
pronounced leukocytosis. fastidious: slow growing culture. may be negative if patient is immunized or on antibiotics. PCR and ELISA good, but not standardized. adults with prolonged cough may have negative results
b. pertussis treatment
macrolides prevent disease from progressing and transmitting. supportive care required. admit for supplemental oxygen and mucus suctioning. corticosteroids and albuterol control cough.
