Haemophilus and Bordetella Flashcards
Very tiny GNRs, very fastidious, capnophilic
Haemophilus
Hemin/hematin, derived from RBCs, heat stable
X factor
NAD; Present in yeast extract (CHOC), RBCs contain this w/ an enzyme inactivator, produced by S. aureus, Neisseria, and S. pneumoniae
V factor
Why is a suspension first made in broth before testing for X and V factor?
To dilute any X factor carried over from the plate
These two medias do not contain any X or V factor
T. soy or Mueller Hinton agar
SBA contains which factors?
X only
Chocolate agar contains which factors?
X and V
Rabbit blood agar contains which factors?
X and V
Fildes enrichment contains which factors?
X and V
Rabbit or horse blood hemolysis looks for the presence of ____ hemolysis
Beta
Which two species are beta hemolytic?
H. haemolyticus and H. parahemolytics
Alternative test for determining X factor; eliminates problem of hemin carryover; fluorescence positive
Porphyrin test
Meningitis was the leading cause in young children before Hib vaccine and was caused by ____ ____
H. influenzae
This is a secondary invader after H. influenzae
Pneumonia
Infection from H. influenzae in the respiratory tract area
Otitis media, epiglottitis
Primary virulence factor of H. influenzae
Capsule
Serotypes of H. influenzae are based on the ____
Capsule
Encapsulated strains of H. influenzae are more likely to be ____, whereas nonencapsulated strains are ____ and often part of the normal respiratory flora
Invasive; noninvasive
Vaccination against invasive Type b strains of H. influenzae
Hib (“Haemophilus influenzae type b”) vaccine
Blood cultures are positive in vasive infections, smooth colonies on chocolate agar, requires both X and V factors, non-hemolytic on Rabbit blood agar
H. influenzae
Requires only V factor, hemolytic on rabbit blood agar
H. parahemolyticus
Requires only V factor, non-hemolytic on rabbit blood agar
H. parainfluenzae
Requires X and V facctors, hemolytic on rabbit blood agar
H. hemolyticus
Former strain of and identified as H. influenzae, causative agent of contagious conjunctivitis (“pinkeye”)
H. aegyptius
Biogroup of H. influenzae primarily in South America; agent of Brazilian purpuric fever (BPF) an ddpurulent conjuctivitis; high mortality rate
H. aegyptius
Not prt of normal flora; agent of “soft chancre” or “genital ulcer disease”; STD; painful ulcerative genital lesion; enlarged lymph nodes; very fastidious; slow grower (5-7 days) on chocolate agar
H. ducryei
HACEK group; indigenous to upper respiratory tract; fastidious; endocarditis, septicemia in immunocompromised patients
Aggregatibacter (Haemophilus) aphrophilus
Gram variable pleomorphic rods; common cause of bacterial vaginosis; can be sexually transmitted
Gardnerella vaginallis
↑ in pH of vaginal fluid (> 4.5), ↓ Lactobacillus (normal flora), overgrowth of seeral normal flora organisms, not an infection
Bacterial vaginosis
How can you diagnose bacterial vaginosis?
Culture is NOT useful; direct exam for “clue cells” (wet prep or gram stained); foul odor of clear, watery exudate; amine test in 10% KOH or vaginal pH > 4.5
Describe clue cells
Squamous epithelial cells plastered w/ variable rods
Does not require X or V factors; inhibition by SPS (sodium polyanethol sulfonate) disk, S. pneumoniae inhibition
G. vaginalis
Stain poorly, small GN coccobacilli,, noninvasive, does not require X or V factors
Bordetella
Agent of pertussis or “whooping cough”, spread by respiratory route
Bordetella pertussis
Toxin produced by organism in B. pertussis ____ ____, and causes accumulation of thick mucous
Paralyzes cilia
What are the 3 stages of pertussis?
- Catarrhal
- Paroxysmal
- Convalescent
Symptoms of a cold, duration of 1-2 weeks, the IDEAL time to culture, rhinorrhea, malaise, fever, sneezing, anorexia
Catarrhal stage
Characteristic cough/whoop, duration of 2-4 weeks, vomiting, leukocytosis
Paroxysmal stage
Duraction for (3-4 weeks) or longer; diminished paroxysmal cough, development of secondary complications such as pneumona, seizures, and encephalopathy
Convalescent stage
Describe pertussis in infants
Life-threatening, choking, apena, may not be a cough
Describe pertussis in adults
Hernia, broken ribs from coughing, often undiagnosed or misdiagnosed, high risk for transmitting disease to infants
Lab identification of B. pertussis by 4 methods
- Culture
- PCR
- Nasopharyngeal culture
- Cough plates
Recommended method for culture for B. pertussis
Nasopharyngeal culture using flexible calcium alginate or Dacron swabs
B. pertussis secretes ____ ____ which builds up and inhibits growth; how do we prevent this?
Fatty acids; charcoal or increased blood in medium to neutralize fatty acids
Which types of media are used to isolate colonies of B. pertussis?
- Bordet-Gengou (potato-glycerol w/ increased blood)
- Charcoal cephalexin blood agar
- Regan-Lowe agar (incubate 7 days)
- Amies (w/ charcoal) or Regan-Lowe transport media
Vaccines for infants vs. adults
DTaP for infants, TdaP booster for adults (aP = acellular pertussis, D = Diphtheria, T = tetanus)
Increased incidence of B. pertussis due to…
Non-immunized children, vaccines are serotype specific or short-lived, adults not receiving boosters
Small percentage of “whooping cough” cases, milder disease, brown pigment, may grow on SBA, MAC agar
B. parapertussis
Present in dogs (kennel cough) and other animals, mild respiratory infection, RAPID UREASE, cross reacts w/ B. pertussis and B. parapertussis on fluorescent Ab, may grow on SBA or MAC agar
B. bronchiseptica
If you don’t have any X factor, what can you use?
SBA
If you don’t have any V factor what can you do?
Add yeast to T. soy (Staph streak)
If you don’t have any XV factor, what can you do?
SBA w/ Staph streak (satellitism)
