Shared Flashcard Set

Details

Gram Negative Fastidious Rods
Haemophilus, HACEK group, Bordatella, Legionella
29
Microbiology
Graduate
04/03/2011

Additional Microbiology Flashcards

 


 

Cards

Term
Haemophilus influenzae characteristics
Definition

gram negative rods (often coccobacilli)

non-motile

fastidious

facultative

virulent strains are encapsulated

Term
Haemophilus influenzae frequently colonizes the human:
Definition

nasopharynx

most are non-capsulated

transmission: airborne/direct contact w/ secretions/fomites

Term
virulence factors of Haemophilus influenzae
Definition

-type b capsule: linear polymer of polyribitol phosphate (PRP); prevent opsonization; assists immune evasion & systemic disease

-pili/non-pilus structure related to adherence?

Term
Diseases caused by Haemophilus influenzae:
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

Term
Diseases caused by unencapsulated forms of Haemophilus influenzae (non type able haemophilus influenzae?):
Definition

otitis media

conjunctivitis

sinusitis

pneumonia

Term
fastidious bacterium
Definition
bacterium will not grow on commonly used agar (blood/nutrient)
Term
identify Haemophilus influenzae
Definition

small gram- coccobacilli (CSF)

chocolate agar

needs X (hemin) & V (NAD) growth factors (tryptose agar plate)

*Haemophilus parainfluenzae only needs growth factor V

Term
describe the Haemophilus influenzae satellite phenomenon
Definition
H. influenzae can grow on blood agar in "satellite" orientation around Staphylococcus aureus colony (these colonies excrete NAD & supports Hi growth)
Term
Name the disease caused by Haemophilus influenzae biogroup aegyptius
Definition

Brazilian purpuric fever

-initial conjunctivitis-->high fever, vomiting, abdominal px

-pediatric disease

-left untreated: (12-48h) petechiae, purpura, & shock-->death

Term
characteristics and epidemiology of Haemophilus ducreyi:
Definition

genetically very different from other Haemophilus

highly fastidious coccobacillus (X factor req)

susceptible to dehydration (common among STI agents)

more common in men

Term
What is the disease commonly caused by Haemophilus ducreyi?
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

Term
Identify Haemophilus ducreyi
Definition

gram- coccobacilli "rice grain" morphology (swab lesion)

multiplex PCR for H. ducrey, T. pallidum, K. granulomatis, HSV 1&2

Term
Names of HACEK species: (similar to Haemophilus)
Definition

Haemophilus parainfluenzae (10% of bacteria in saliva)

Haemophilus aphrophilus

Haemophilus paraphrophilus

Actinobacillus actinomycetemocomitans

Cardiobacterium hominis

Eikenella corrodens

Kingella kingae

Term
common cause of septic arthritis in children <24mo
Definition
Kingella kingae
Term
Name the pathogen that causes 3% community-acquired subacute endocarditis:
Definition
HACEK species
Term
HACEK species characteristics
Definition

gram- small rods

common normal flora of URT & oral cavity

not as fastidious as other Haemophilus

Term
characteristics of Bordetella:
Definition

very small

strict aerobe

gram- coccobacillus

2 important species: pertussis & parapertussis

Term
Bordetella pertussis characteristics
Definition

gram gram- coccobacilli slow-growth fastidious

non-motile

oxidize AA

carbohydrate NON-fermenter

Term
epidemiology of Bordetella pertussis
Definition

pediatric pathogen

aeosols

humans ONLY reservoir

still endemic w/ vaccine

Term
end effect of the virulence factors of Bordetella pertussis
Definition

bacterial attachment to tracheal cells

binding to phagocytic cells (CR3)

Term
Bordetella pertussis produces which toxin in particular?
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)

Term
pathogenesis of Bordetella pertussis:
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)
Term
Describe the disease caused by Bordetella pertussis:
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

Term
What causes the hallmark paroxysmal cough?
Definition

Pertussis toxin?

Yes: vaccine w/ toxin only prevents disease

No: cough occurs in pts infected w/ B. parapertussis (does not produce pertussis toxin)

Term
Identify Bordetella pertussis
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

Term
characteristics/epidemiology of Legionella
Definition

gram-

pleomorphic coccobacilli

aquatic saprophyte: found in freshwater, air-conditioners, shower heads, lakes, streams

transmission: inhalation

risk factors: smoking, chronic pulm disease, alcoholism

 

Term
pathogenesis of Legionella
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]
Term
diseases caused by Legionella
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

Term
identification of Legionella
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)

Supporting users have an ad free experience!