Term
| Haemophilus influenzae characteristics |
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Definition
gram negative rods (often coccobacilli)
non-motile
fastidious
facultative
virulent strains are encapsulated |
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Term
| Haemophilus influenzae frequently colonizes the human: |
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Definition
nasopharynx
most are non-capsulated
transmission: airborne/direct contact w/ secretions/fomites |
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Term
| virulence factors of Haemophilus influenzae |
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Definition
-type b capsule: linear polymer of polyribitol phosphate (PRP); prevent opsonization; assists immune evasion & systemic disease
-pili/non-pilus structure related to adherence? |
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Term
| Diseases caused by Haemophilus influenzae: |
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Definition
1. Haemophilus Meningitis: mainly among unimmunized; bacteremic spread from nasopharynx
2. Epiglottitis: pts appear sick, restless, pale/cyanotic, tachycardic, complete airway obstruction (rare due to HiB vaccination); swollen epiglottis/aryepiglottic folds |
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Term
| Diseases caused by unencapsulated forms of Haemophilus influenzae (non type able haemophilus influenzae?): |
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Definition
otitis media
conjunctivitis
sinusitis
pneumonia |
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Term
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Definition
| bacterium will not grow on commonly used agar (blood/nutrient) |
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Term
| identify Haemophilus influenzae |
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Definition
small gram- coccobacilli (CSF)
chocolate agar
needs X (hemin) & V (NAD) growth factors (tryptose agar plate)
*Haemophilus parainfluenzae only needs growth factor V |
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Term
| describe the Haemophilus influenzae satellite phenomenon |
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Definition
| H. influenzae can grow on blood agar in "satellite" orientation around Staphylococcus aureus colony (these colonies excrete NAD & supports Hi growth) |
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Term
| Name the disease caused by Haemophilus influenzae biogroup aegyptius |
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Definition
Brazilian purpuric fever
-initial conjunctivitis-->high fever, vomiting, abdominal px
-pediatric disease
-left untreated: (12-48h) petechiae, purpura, & shock-->death |
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Term
| characteristics and epidemiology of Haemophilus ducreyi: |
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Definition
genetically very different from other Haemophilus
highly fastidious coccobacillus (X factor req)
susceptible to dehydration (common among STI agents)
more common in men |
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Term
| What is the disease commonly caused by Haemophilus ducreyi? |
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Definition
Chancroid:
-genital ulcers/inguinal adenitis
-less common in US
-50% develop enlarged/tender inguinal lymph node
-multiple ulcers coalesce => giant ulcer
-progression: 4-7d(papule w/ surround edema); +2-3d(pustule-->ruptures); eventually is a sharply circumscribed ulcer (not indurated); painful & bleeds easily |
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Term
| Identify Haemophilus ducreyi |
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Definition
gram- coccobacilli "rice grain" morphology (swab lesion)
multiplex PCR for H. ducrey, T. pallidum, K. granulomatis, HSV 1&2 |
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Term
| Names of HACEK species: (similar to Haemophilus) |
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Definition
Haemophilus parainfluenzae (10% of bacteria in saliva)
Haemophilus aphrophilus
Haemophilus paraphrophilus
Actinobacillus actinomycetemocomitans
Cardiobacterium hominis
Eikenella corrodens
Kingella kingae |
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Term
| common cause of septic arthritis in children <24mo |
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Definition
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Term
| Name the pathogen that causes 3% community-acquired subacute endocarditis: |
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Definition
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Term
| HACEK species characteristics |
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Definition
gram- small rods
common normal flora of URT & oral cavity
not as fastidious as other Haemophilus |
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Term
| characteristics of Bordetella: |
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Definition
very small
strict aerobe
gram- coccobacillus
2 important species: pertussis & parapertussis |
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Term
| Bordetella pertussis characteristics |
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Definition
gram gram- coccobacilli slow-growth fastidious
non-motile
oxidize AA
carbohydrate NON-fermenter |
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Term
| epidemiology of Bordetella pertussis |
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Definition
pediatric pathogen
aeosols
humans ONLY reservoir
still endemic w/ vaccine |
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Term
| end effect of the virulence factors of Bordetella pertussis |
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Definition
bacterial attachment to tracheal cells
binding to phagocytic cells (CR3) |
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Term
| Bordetella pertussis produces which toxin in particular? |
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Definition
Pertussis toxin:
-bact adherence
-similar to cholera toxin (5 binding subunit & 1 active subunit; binding subunit attaches w/ host cell to insert enzymatic activity => ADP-ribosylation of G protein => incr [cAMP] => host cell secretes water) |
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Term
| pathogenesis of Bordetella pertussis: |
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Definition
| bacteria attach to nasopharyngeal epithelial cells (adhesin molecules) --> bact replication @ attachment site (making toxins) --> bacterial invasion --> bacteria live intracellularly (systemic effects due to toxin effects) |
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Term
| Describe the disease caused by Bordetella pertussis: |
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Definition
Whooping Cough:
-most common in pre-school/school-aged kids (clinical present variable by age)
-progress from common cold symp-->catarrhal stage-->paroxysmal phase (can last up to 3 mo)
-complications: bronchopneumonia, encephalopathy, hypoxia
-neurological events (seizures & encephalopathy) <= hypoxia or sleep apnea |
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Term
| What causes the hallmark paroxysmal cough? |
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Definition
Pertussis toxin?
Yes: vaccine w/ toxin only prevents disease
No: cough occurs in pts infected w/ B. parapertussis (does not produce pertussis toxin) |
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Term
| Identify Bordetella pertussis |
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Definition
culture mucous from posterior nasopharynx
requires enriched media (Bordet-Gengou or blood charcoal agar) AND V&X factors
intolerant: fatty acids => no cotton swabs
use dacron or Ca++alginate swabs
*Regan-Lowe charcoag agar better than B-G |
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Term
| characteristics/epidemiology of Legionella |
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Definition
gram-
pleomorphic coccobacilli
aquatic saprophyte: found in freshwater, air-conditioners, shower heads, lakes, streams
transmission: inhalation
risk factors: smoking, chronic pulm disease, alcoholism
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Term
| pathogenesis of Legionella |
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Definition
| enters lungs (aspiration/inhalation) --> pili/HSPs/outermem proteins attach to host cell --> binds alveolar macrophages => its own phagocyto --> prevent lysosome-phagosome fusion (via blocking acidification) --> replicates in cytosol until host cell rupture [CMI most important in fending off this intracellular pathogen] |
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Term
| diseases caused by Legionella |
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Definition
1. Pontiac fever
-acute self-limiting
-pneumonia does NOT develop
2. Legionnaires' disease (Pneumonia)
-usually atypical (non-productive cough)
-gastrointestinal symptoms
-systemic signs develop
-CXR: alveolar infiltrates
-diarrhea; high fever; hyponatremia; many neutrophils but no organism in gram stain of resp samples |
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Term
| identification of Legionella |
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Definition
very thin coccobacilli => stain poorly in sputum gram stain
fastidious (req Fe & cysteines)
*buffered charcoal yeast extract (BCYE) agar
fluorescent antibody test of sputum
fatty acid intolerant
antibodies detectable in urine (PCR based test common) |
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