Aerobic Gram Negative Bacteria
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Associated with Tularemia, Potential bioterrorism agent, Skin ulcers at the site of inoculation, Lymph node infections, Eye infections, Lung infections, GI system infections, Intracellular bacteria resist phagocytosis
Faintly staining coccobacilli
Medium choice is glucose-cystine blood agar
Agglutination and directs fluorescent antibody tests are used to confirm
What biosafety level is required when handling specimens containing Francisella?
Biosafety level 3
What 4 species infect humans?
- B. melitenis
- B. abortus
- B. suis
- B. canis
What biosafety level is required when handling specimens with Brucella?
Biosafety level 3
Associated with Brucellosis (also known as undulant fever), Potential bioterrorism agent, Facultative intracellular parasite
Isolated from Blood and Bone marrow
Incubation period is 1-3 Weeks
Grows on buffered charcoal yeast extract (BCYE) and modified Thayer-Martin agars
Requires 10% CO2 and 3 weeks to grow
Confirmation tests are usually done serologically
Phage and dye sensitivity tests are used for ID to the species level
Gram stain - poorly stained coccobacilli, single or in pairs
Will NOT grow on MAC
Media used: Bordet-Gengou (potato infusion), Regan-Lowe (charcoal-horse blood agar), Media are often made selective by adding cephalexin
What are the 3 stages of pertussis (whooping cough)?
- 1) Catarrhal - general flu-like symptoms
- 2) Paroxysmal - Repetitive coughing episodes
- 3) Convalescent - Recovery phase
What media is used to grow Bordetella pertussis?
- Bordet-Gengou (potato infusion)
- Regan-Lowe (charcoal-horse blood agar)
- Media are often made selective by adding cephalexin
What clinical conditions are associated with Bordetella parapertussis?
Mild respiratory infections
What clinical conditions are associated with Bordetella bronchiseptica?
What are the tests and results used to ID Bordetella and it's sub-species?
- Gram stain - poorly stained coccobacilli, single or in pairs
- Most will grow on MAC - except B. pertussis
- Urease POS
- B. pertussis - Urease NEG
Associated with Cellulitis, Endocarditis, Gum disease
Grows well on SBA and Chocolate but not on MAC that show starlike centers
What subspecies of Pasteurella causes the most human infections?
Associated with Cellulitis, Osteomyelitis, Meningitis, Joint infections, Pneumonia
Grows on nonselective media but not MAC
Pleomorphic - Gram Negative Coccobacilli that may show bipolar staining
Very susceptible to penicillin
Associated with Abcesses of the oral cavity and Human bite wound infections
Approx. 50% of strains corrode or pit the agar
Requires hemin (Factor X) for growth unless 5-10% CO2 is present
When was Legionella found?
1st discovered in 1976 as the cause of pneumonia in people attending the American Legion convention in Philadelphia
What is the most common Legionella subspecies to cause human infections?
Legionella pneumophilia serogroup 1
Associated with Legionellosis (asymptomatic), Pneumonia (mild to severe), Legionnaires disease (primary pneumonia), Pontiac fever (mild with flulike symptoms)
Most common lab assay: Urine antigen test
Poorly staining gram negative bacilli but it is better to use 0.1% basic fuchsin as the counter stain instead of safranin
Most biochemical tests are NEG
Most species will autofluroesce when exposed to UV light
Direct fluorescent antibody test
Nucleic acid probes
What media is used to grow Legionella?
- Some will grow on Brucella blood agar (more nutritious than SBA
- Require L-cysteine for growth
What nutrient is needed for growth of Legionella?
What clinical conditions are associated with Chromobacterium?
Wound infections acquired from contaminated water or soil
What does Chromobacterium look like on a plate?
Purple or violet pigment on nutrient agar
Bacterial vaginosis (BV), UTIs, PID, Postpartum sepsis, May infect the newborn
Has Clue cells (epithelial cells with numerous bacteria attached)
Amsel and Nugent scoring systems are used to diagnose BV (because cultures alone are too sensitive)
What is the Amsel and Nugent scoring system?
- Used to diagnose Gardnerella vaginalis
- Approximately 50-60% of women who do NOT meet the criteria for BV are POS for G. vaginalis
Associated with Trench fever, Causes growth of neoplastic blood vessels in various parts of the body (bacillary angiomatosis), Endocarditis
Gram Neg curved bacilli
Spread by human lice
What bacteria is associated with the clinical conditions:
Bacillary peliosis hepatitis
Associated with endocarditis
Gram Stain: Short chains or pairs, or rosettes of irregularly staining bacilli with bulbous ends
Requires CO2 for initial isolation
Growth is enhanced in media containing yeast extract
Weakly Indole POS
Associated with Rat-bite fever (animal bites), Haverhill fever (ingestion of contaminated food and water), Blood infections, Synovial fluid infections, Abcess infections
Gram-negative pleomorphic bacillus
Grows on BAP (15% is optimal) incubated in CO2
Where are the spores located on Bacillus species and there characteristics?
- Centrally or Terminally located
- Bacterial spores can survive adverse conditions for prolonged periods of time
What are the pathogenic species of Bacillus?
- B. anthracis (anthrax)
- B. cereus (food poisoning and wounds)
Large, non-hemolytic colonies with filamentous projections - referred to as "Medusa-head" colonies
Straight bacilli with square ends (boxcar morphology) appearing in chains and singly with spores
Does not grow on PEA (phenylethylalcohol) at 24 hours
What are the clinical conditions associated with bacillus anthracis?
- Cutaneous anthrax - most common, characterized by necrotic skin lesions called black eschars
- Pulmonary anthrax - "Wool-sorter's disease", spread by the inhalation of spores from sheep's wool
- Gastrointestinal anthrax - Rarest form, spread by ingestion of spores
- Potential bioterrorism agent
Associated with Food poisoning, Wound infections, Opportunisitic eye, bone, and brain infections
Resistant to 10 microgram of penicillin
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