gram-positive bacilli part one
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Gram-Positive Bacilli Part One. MLAB 2434: Microbiology Keri Brophy -Martinez. General Characteristics: Bacillus. Habitat Thermal springs, fresh and salt water, soil, on plants Aerobic Spore-formers Resistant to radiation, heat, disinfections, and desiccation - PowerPoint PPT PresentationTRANSCRIPT
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Gram-Positive BacilliGram-Positive BacilliPart OnePart One
MLAB 2434: MicrobiologyKeri Brophy-Martinez
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General Characteristics: General Characteristics: BacillusBacillus
Habitat◦Thermal springs, fresh and salt water,
soil, on plantsAerobicSpore-formers
◦Resistant to radiation, heat, disinfections, and desiccation
Mostly contaminants in clinical specimens◦EXCEPTION: Bacillus anthracis
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More on SporesMore on SporesProduced when the bacteria gets stressed
◦ Drying◦ Temperature extremes
Aid in organism’s survival
Heat shock induces spores◦ Temperature raised to 56o
Gram stain◦ Appear as clear areas within the bacterial cell
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SignificantSignificant Bacillus Bacillus Species SpeciesBacillus anthracis
◦ Agent of anthrax, a disease in livestock◦ Humans acquire infection by contamination of
wound or ingestion or inhalation of sporesBacillus cereus
◦ Causes food poisoning◦ An opportunist
Bacillus subtilis◦ Common laboratory contaminant◦ Used in sterility testing
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Bacillus anthracisBacillus anthracisCutaneous anthrax
◦ “Malignant pustule” (also called “black escher”)◦ Woolsorter’s disease/ Rag-pickers disease◦ Organisms gain access through cuts; localized
infection◦ Majority of cases in the world are cutaneous
Inhalation anthrax◦ Acquired through inhalation of spores◦ May result in respiratory distress and death
Gastrointestinal◦ Acquired by ingestion of contaminated raw meat◦ Usually fatal
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Bacillus anthracisBacillus anthracis: : Clinical Infections in Humans Clinical Infections in HumansCutaneous anthrax
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Laboratory DiagnosisLaboratory DiagnosisMedia
◦Most species grow well on SBA Most species beta-hemolytic, except B.
anthracis
◦No growth on MacConkey◦Fast growers◦Colony characteristics vary
Catalase positive
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Laboratory DiagnosisLaboratory Diagnosis
Goal in identification is to RULE OUT B. anthracis
If B. anthracis is suspect, MUST work under safety hood
Other Bacillus, identified to genus level ONLY
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Identification Identification of Bacillus of Bacillus anthracisanthracis
Microscopic morphology◦ Large, square-
ended gram-positive rods
◦ Bamboo appearance
◦ Spores may be absent in patient smears
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Identification Identification of Bacillus of Bacillus anthracisanthracis
Colony Morphology◦ Nonhemolytic on blood
agar; raised, large, grayish white, irregular, fingerlike edges
◦ “Medusa head” or “beaten egg whites”
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Bacillus cereusBacillus cereusFood poisoning
◦ Diarrheal syndrome Associated with meat, poultry, and soups Incubation period of 8 to16 hours Fever uncommon Resolves within 24 hours
◦ Emetic form Associated with fried rice Abdominal cramps and vomiting Incubation period of 1 to 5 hours Resolves in 9 hours
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Bacillus cereusBacillus cereusLocal infections
◦ Postsurgical/traumatic wounds◦ Burns◦ Eye infections
Rare conditions◦ Meningitis◦ Bacteremia◦ Endocarditis◦ Osteomyelitis
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Bacillus subtilisBacillus subtilis
Found in the environmentCommon laboratory and hospital contaminantUsed as a QC agent for sterilization procedures
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Key Characteristics of Key Characteristics of Bacillus SpeciesBacillus Species
Characteristic B. Anthracis B. Cereus Other Bacillus
Beta-hemolysis Negative Positive, Large zones
variable
Motility Negative Positive Positive
Pencillin Sensitive Resistant Variable
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ReferencesReferences http://www.atsu.edu/faculty/chamberlain/golden2000/
case5.htm http://chesschumpion.blogspot.com/2007/03/time-to-put-on-
your-thinking-caps.html http://en.wikipedia.org/wiki/File:Bacillus_subtilis_Gram.jpg https://labs.uhstx.com/clinical_int/dols/appb.htmlhttp://
www.iccb.state.il.us/pt3/mod/science/mod_bio111/mod10/p4.html
http://www.flickr.com/photos/microbeworld/sets/72157625392265538/detail/http://www.uaz.edu.mx/histo/pathology/ed/ch_9b/c9b_clue.htm
Kiser, K. M., Payne, W. C., & Taff, T. A. (2011). Clinical Laboratory Microbiology: A Practical Approach . Upper Saddle River, NJ: Pearson Education.
Mahon, C. R., Lehman, D. C., & Manuselis, G. (2011). Textbook of Diagnostic Microbiology (4th ed.). Maryland Heights, MO: Saunders.