Bacillus Flashcards
Bacillus spp.
- Aerobic
-non acid fast - Spore forming
- catalase positive
- non branching
- 5% blood sheep agar, blood culture media, nutrient broths, PEA and CA media
Clostridium spp.
- Anaerobic
- non acid fast
- spore forming
- catalase negative
- non branching
Cutaneous Anthrax
- most human infections
- endosperm’s come in through break in the skin
- obtained from contact with animal products
- 2-6 incubation
- ring of vesicles appear that develop into an ulcer (eschar) on the skin
- no fever, fatal if lesions are on face and neck (obstructed airway)
- mortality rate of 1%
GI Anthrax
- ingestion of endospores
- eating raw or undercooked meat
1. Oral-pharyngeal lesions: sore throat , lymphadenopathy, edema of throat and chest
2. GI lesions: nonspecific symptoms that progress to abdominal pain, nausea, vomiting, anorexia, fever, bloody diarrhea, and hematemesis - mortality higher than cutaneous
Inhalation (Wool-sorters Anthrax)
- inhalation if endospores
- most deadly
- exposure to endospores from handling infected animal hides, hair, or fibers
- macrophages ingest these in the lungs and transport them to the lymph nodes
- flu like disease: fever, chills, fatigue, cough, nausea, vomiting
-then progression to respiratory distress, edema, cyanosis, shock, and death. - widened mediastinum
Injectional Anthrax
- happens through contaminated drugs, usually heroin (animal skins used to move drugs)
- skin site is bruised, no eschar
- leads to systemic dissemination and septic shock
-not seen in US
Anthracis Presumptive Identification
- large, non-hemolytic colony that stands up like a beaten egg (positive tenacity test)
- gram stain: large, gram positive rods
- catalase positive
- nonmotile
Anthracis Confirmatory Identification
- detection of antibodies by indirect hemagglutination and enzyme linked immunosorbent assays
-Multilocus Sequence Typing (MLST) - DNA microarrays
- MALDI-T identifies PA, EF, and LF proteins
-PCR is most rapid test: detects several targets on the chromosome and virulence plasmids (which code for the biosynthesis of the capsule)
Environment Location comparison
Both B. cereus and B. anthracis are found in soil
Mode of Transmission comparison
B. Anthracis:
- injectional, inhalation, GI, and Cutaneous
B. Cereus
- Trauma
- food borne illness (meats, vegetables, rice), immunocompromised, skin infections or systemic (endocarditis or septicemia), urinary or respiratory tract, HAI, contaminated drugs
Morphology Comparison
B. Cereus:
- beta hemolytic
- large feathery
- motile, non encapsulated
B. Anthracis
- gray, flat, irregular swirling projections “Medusa head”, ground glass appearance
- non-hemolytic (gamma)
- stands up like a beaten egg (positive tenacity test)
-non motile
- gram stain: large, positive rods
- catalase positive
Specimen Processing Comparison
- Heat or alcohol shock prior to plating and selects for spore forming bacilli
Anthracis
- leak proof primary container and secondary container prior to antibiotic therapy
- vesicular fluid from eschar, blood cultures, stool, CSF, pleural fluid, tissue, ascites fluid, sputum, bronchitis biopsy, or serum
- use formaldehyde prior to disposal: must alert cdc within 7 days upon ID
Bioterrorism select agent comparison
B. Anthracis
- category A agent: those presenting the highest risk to public health and national security because they are easily transmitted from person to person and have high mortality rates
B. Cereus
- not a select agent
Biohazard precautions comparison
- wash hands
- wear gloves
- mask, gown, eye protection
- take care to prevent injuries
- dispose of single use items properly
- ensure the reusable equipment is sterilized