Gram-negative coccobacilli Flashcards
How is Haempohilus ducreyi transmitted?
sexual contact
What are the clinical manifestations of Haemophilus ducreyi? (1)
chancroid-penile lesion that becomes a nonindurated painful ulcer with sharp margins (Compare with hard chancre of syphilus). May progress to infect lymph nodes, forming bubo.
How does Haemophilus vaginalis (Gardnerella) gram stain?
variable
What part of the world is most associated with Haemophilus ducreyi?
common in tropical countries
How does Haemophilus influenzae gram stain?
negative
What is the morphology of Haemophilus vaginalis (Gardnerella)?
coccobacilli
What lab findings are useful to help diagnose Haemophilus vaginalis (Garnerella)? (2)
positive whiff test (fishy odor after application of 10% KOH); clue cells
When is the H. influenzae vaccine given?
between 2 and 18 months of age
Name four diseases caused by H. influenzae.
epiglottitis, meningitis, otitis media, pneumonia
How does Haemophilus ducreyi gram stain?
negative
How is Bordetella pertussis transmitted?
human to human, repiratory droplets.
What lab findings are useful to help diagnose Bordetella pertussis? (3)
nasopharyngeal swab will give colonies that grow on Bordet-Gengou medium; small colonies glisten “like pearls”; PCR can make rapid identification.
What are the clinical manifestations of Haemophilus influenzae? (5)
otitis media-pain, fever, ruptured tympanic membrane (pus, blood). Also meningitis, sinusitis, pneumonia, acute epiglottitis.
What symptoms are associated with G. vaginalis infection? (3)
vaginosis-greenish vaginal discharge, fishy odour, not painful
What are the laboratory characteristics of G. vaginalis? (2)
pleiomorphic, gram-variable rods; clue cells-vaginal epithelial cells covered with bacteria are visible under a microscope
What is the morphology of Bordetella pertussis?
coccobacilli, encapsulated
Identify relevant epidemiology and risk factors associated with Bordetella pertussis. (2)
very contagious, mostly affecting young children.
How does Bordetella pertussis gram stain?
negative
What lab findings are useful to help diagnose Haemophilus influenzae? (2)
requires chocolate agar (lysed RBC’s that provide heme and NAD) to grow; Colonies grow as satellites next to S. aureus.
Which mechanism do pertussis toxin and choleratoxin have in common?
act via ADP ribosylation to permanently activate adenyl cyclase, resulting in increased cAMP.
T/F: H. influenzae causes the flu
false-influenza virus causes the flu
Identify the major virulence/toxicity factors associated with Bordetella perussis. (2)
filamentous hemagglutinin on pili help organism to stick to epithelium. Pertussis toxin stimulates G protein to raise [cAMP] in epithelial cells and also causes lymphocytosis by inhibition of chemokine receptors.
What is the morphology of Haemophilus influenzae?
coccobacilli
Identify the major virulence/toxicity factors associated with Haemophilus influenzae. (2)
secretes a protease that digests secretory IgA. Encapsulated strains can reach the meninges.
What is the morphology of Haemophilus ducreyi?
coccobacilli
Describe the clinical picture of Bordetella pertussis infection. (3)
pertussis (whooping cough)-7-10 days incubation followed by mild URT infection for 1 or 2 weeks and then a “whooping” cough that produces copious mucus. May be followed by vomiting.
