Fastidious Gram Negative Rods Flashcards
How could you identify a culture of Haemophilus influenzae?
gram stain?
motility?
growth requirements?
What cultures do they grow on?
where do they typically colonize?
mode of transmission?
- gram stain?
- gram negative coccobacilli (pleomorphic)
- motility?
- non-motile
- growth requirements?
- fastidious
- facultative
- X+V growth factors (hemin & NAD)
- Cultures grow on?
- Grow on chocolate agar
- do NOT grow on blood agar
- can grow on blood agar as satellite colonies around S. aureus (bc it excretes NAD & yields hemin from degradign RBC)
- where do they typically colonize?
- nasopharynx
- sample from CSF in patient with meningitis
- airborne transmission
What are the major virulence factors of Haemophilus influensae?
- pili and non-pilus structures (help w/ adherence)
- type b capsules contain ribose, ribitol, phosphate
- responsible for >95% invasive infections
- rare b/c Hib vaccine
- invasive disease in vaccinated ‘A’
- polyribitol phosphate (PRP) is a major virulence factor
- antiphagocytic, role in immune evasion & systemic disease
What disease is characterized by the following symptoms?
- initially mild URT disease (fever & systemic signs); headache; confusion
- high level bacteremia (in CSF & blood)
- patients is not immunized
What is the likely bacterial source?
meningitis
H. influenzae (serotype B)
What disease is characterized by the following symptoms?
- patient is 2-4 years old
- swollen epiglottis & aryepiglottic folds
- patients appear restless, pale, or cyanotic, tachycardiv
What is the probable bacterial cause?
Epiglottitis
H. influenzae (serotype b)
What disease is characterized by the following symptoms?
Problems with a single large, weight bearing joints in children
(was a most common cause in chldren younger than 2 before vaccine)
What is the probable bacterial cause?
Septic arthritis
H. influenzae
What disease can un-encapsulated (non-typeables) H. influenzae cause?
- pneumonia
- otitis media
- conjunctivitis
What are the 5 bacteria that are most likely to cause otitis media?
What disease is characterized byt the following symptoms?
initially conjuctivitis
days to weeks later – high fever, vomiting, abdominal pain
In 12-48 hrs - petechiae, purpura, shock–> death
What bacteria is the likely cause?
Brazilian purpuric fever
H. influenzae aegyptius
How could you identify a disease caused by H. ducreyi?
How well does it culture?
gram stain?
- Does not culture well
- gram stain of lesion maerial
- grma negative coccobacilli w/ PMN
What disease is characterized by the following symptoms?
4-7 days after sex papule w/ edema; then 2-3 days later it ruptures
painful genital ulcers and inguinal lymphadenitis in men
asymptomatic in women
Chancroid
Haemophilus ducreyi
susceptible to drying out
STD
What are the species members of the HAECK group?
- H. parainfluenzae
- H. aphrophilus
- H. paraphrophilus
- Aggregatibacter actinomycetemcomitans
- Cardiobacterium hominis
- Eikenella corrodens
- Kingella kingae
How could you identify culture containing one of the HAECK bacteria?
Gram stain?
Growth requirements?
Where are they naturally located?
- gram (-) small rods
- growth requirement
- fastidious – can grow slowly on blood agar
- Location
- URT & oral cavity
- 10% saliva bacteria
What are the major diseases caused by HAECK species?
- S/A endocarditis
- infection of the inner lining of the heart
- nonspecific symptoms (fever, malaise, shortness of breath)
- diagnosed by culture, echocardiography, history and symptoms
- Septic arthritis
- bite wound
- periodontal diseases
How could you identify a culture of Bordetella?
Gram stain?
growth requirement?
preferred agar?
How is it transmitted?
What disease does it cause?
If suspected, how should you take a sample?
- Gram stain
- gram (-) cocobacillus
- Requires X & V factors & enriched mediumm
- Regan-Lowe charcoal agar preferred over Bordet-Gengou
- Transmitted via aerosolized droplets
- Pertussis (whooping cough)
- use dacron or rayon swabs (not cotton)
- sensitive to FA (cotton swabs rich in FA)
- from posterior nasopharynx
What are the major virulence virulence factors employed by B/ pertussis?
- Adhesins
- Fha & Pertactin: agglutinates RBC
- Pertussis Toxin
- Toxins
- Pertussis Toxin: increases cAMP
- Adenylate cyclase: increases cAMP
- Trachael cytotoxin: kills ciliated cells
- LPS: lipid A or lipid X
What is the pathogenesis a pertussis infection?
Describe the progression of symptoms.
- Pathogenesis
- bacterial adhesion attach to ciliated cells
- They replicate at the site of attachment & persis intra-cellularly
- toxins produced are responsible for effects (lymphocytosis)
- Disease Progression
- Catarrhal stage: 7-10 days post exposure & lasts 1-2 weeks
- coryza, lacrimation, mild cough, low fever, and malaise
- Paryoxysmal phase:
- cough more frequent & spasmodic
- repetition >10 cough
- vomiting is frequent - ends with a whoop
- Convalescent stage: in 2-4 weeks; may last 1-3 months
- cough less frequent & severe
- can result in seizure & encephalopathy
- may be do to hypoxia
- or specific bacterial product
- Catarrhal stage: 7-10 days post exposure & lasts 1-2 weeks
How could you identify a sample of Legionellaceae pneumophila?
Gram stain?
growth requirement?
Agar?
mode of transmission?
natural location?
- Gram stain
- gram negative, pleomorphic (stain poorly)
- Growth requirement
- slow growth (3-5d)
- FA intolerant
- require cysteine
- Agar
- buffered charcoal yeast extract (BCYE) agar
- Transmitted through inhalatin of aerosols
- Found in freshwater environment
What is the pathogenisis of a Legionella infection?
- enters lungs through aspiration/inhalation
- OMPs help binding to alveolar macrophages & induce phagocytosis
- blocks acidification (prevents lysosome-phagosome fusion)
- remains intracellular (proliferates until cell ruptures)
- Severe disease in CMI defect 40+
