BACTE LEC: GRAM POS BACILLI

What makes Gram-positive spore-forming bacilli resistant to extreme/injurious conditions?

Dipicolinic acid or calcium dipicolinate.

Does the ability of Bacillus and Clostridium to produce spores relate to their virulence?

No, their ability to produce spores has nothing to do with virulence.

What are the main characteristics of Genus Bacillus regarding oxygen requirement, catalase, and spores?

Gram (+), spore-forming, aerobic bacilli that produce endospores in the presence of oxygen.

What are the main characteristics of Genus Clostridium regarding oxygen requirement and catalase?

Strict anaerobes (though some are aerotolerant), catalase-negative.

What test is used to rapidly differentiate Bacillus and Clostridium?

Catalase test.

What reagent is used in the catalase test to differentiate Bacillus and Clostridium, and what is a positive result?

15% hydrogen peroxide (H2O2); positive result is vigorous bubbling / effervescence.

What is the catalase result for Bacillus?

Positive (+).

What is the catalase result for Clostridium?

Negative (-).

What is the oxygen requirement for Bacillus?

Aerobic (+).

What is the oxygen requirement for Clostridium?

Anaerobic (-) (some are aerotolerant).

What are the factors used for species differentiation within the genera of spore-forming bacilli?

Size of the vegetative cell, sporulation resulting in swelling of the vegetative cell, and biochemical analysis.

What is the routine isolation media for Genus Bacillus?

5% Sheep Blood Agar (SBA).

What media can be used for cultivation of Genus Bacillus besides SBA?

Chocolate agar (CAP), Phenylethyl alcohol agar (PEA), routine blood culture media, and commonly used nutrient broths.

Will Genus Bacillus grow on MacConkey agar?

No, it will NOT grow on MacConkey agar.

What are the incubation conditions and duration for Genus Bacillus?

Detectable growth within 24 hours at 35°C in ambient air or in 5% CO2.

How must Bicarbonate agar be incubated for Bacillus?

Incubated in CO2.

What is the selective media for Bacillus anthracis?

PLET (Polymyxin, Lysozyme, EDTA, Thallous Acetate).

What are the plated media options for Bacillus cereus?

MEYP (Mannitol Egg Yolk Polymyxin B agar) and PEMBA (Polymyxin B Egg yolk Mannitol Bromthymol blue Agar).

What is another name for Bacillus anthracis?

Anthrax bacillus.

Why is Bacillus anthracis considered the most significant Bacillus species?

It is a bioterrorism agent (Category A) that causes anthrax.

What category of bioterrorism agent is Bacillus anthracis?

Category A.

What are the virulence factors of Bacillus anthracis?

Capsule (Poly-gamma D-glutamate) and Exotoxin (with 3 components).

What is unique about the capsule of Bacillus anthracis?

It is composed of Poly-gamma D-glutamate, making it the only bacteria that do not have a polysaccharide capsule.

What is the function of the Bacillus anthracis capsule?

Antiphagocytic.

What stain is used for the Bacillus anthracis capsule?

M'fadyean stain (uses polychrome methylene blue) or India Ink.

What are the 3 components of the exotoxin of Bacillus anthracis?

Lethal factor, Edema factor, and Protective antigen.

What defines Category A bioterrorism agents?

Easily transmitted and can cause high mortality rate.

What are the examples of Category A bioterrorism agents?

Bacillus anthracis (gm + rod), Yersinia pestis (gm

What defines Category B bioterrorism agents?

Not easily transmitted as Category A, can cause low mortality rate.

What is an example of a Category B bioterrorism agent?

Brucella.

What defines Category C bioterrorism agents?

Emerging pathogens that can be engineered for mass spread in the future, can be reproduced or manufactured to be used in biological warfare.

What is an example of a Category C bioterrorism agent?

H1N1 (influenza virus).

What is Cutaneous Anthrax also known as?

Black eschar.

What is the mode of transmission for Cutaneous Anthrax?

Contact with infected spores while handling wool (from sheep).

What is the clinical progression of Cutaneous Anthrax?

From an erythematous papule to ulceration and formation of black eschar on skin at the site of spore penetration 2 to 5 days after exposure; may progress to toxemia and death.

What is the severity and occurrence rate of Cutaneous Anthrax?

Most common but least severe.

What is the mode of transmission for Pulmonary Anthrax?

Ingestion/Inhalation of spores while handling wool.

What are the symptoms of Pulmonary Anthrax?

Malaise with mild fever and non-productive cough progressing to respiratory distress, massive chest edema, cyanosis, and death.

What are the other names used to describe Pulmonary Anthrax?

Woolsorter's disease, Ragpicker's disease, Hide porter disease.

What is the mode of transmission for Intestinal Anthrax?

Ingestion of improperly cooked infected meat (spores).

What does Intestinal Anthrax cause and what areas does it affect?

Causes toxemia and overwhelming sepsis; affects either the oropharyngeal or the abdominal area.

What is the severity and occurrence rate of Intestinal Anthrax?

Least common but most severe.

How is Injectional Anthrax transmitted and who does it affect?

Associated with the use of contaminated drugs of abuse (i.e., Heroin) among addicts.

What Biosafety Level precautions are observed when processing specimens for Bacillus anthracis identification vs when cultured?

BSL-2 precautions when processing specimen; BSL-3 precautions when already cultured.

What are the microscopic features of Bacillus anthracis?

Non-motile, disjointed bamboo fishing rod / bamboo pole appearance (due to square ends), box car morphology on gram stain, centrally located spores, and (+) capsule.

Is box car morphology exclusive to Bacillus anthracis?

No, Clostridium perfringens is actually the one possessing said morphology.

What hemolysis does Bacillus anthracis exhibit on 5% SBA?

Gamma-hemolytic (non-hemolytic).

What is the colony consistency of Bacillus anthracis on plated media?

Beaten egg white consistency; colonies are very tenacious (viscous).

What is the colonial appearance of Bacillus anthracis on BAP?

Swirling projections or cut glass appearance giving it Medusa head, Lion head, or Comet tail appearance.

Is Medusa head appearance unique to Bacillus anthracis?

No, it is also exhibited by Clostridium septicum.

What pattern does Bacillus anthracis form in tube media (semi-solid gelatin media butt)?

Inverted fir tree or inverted pine tree pattern with slow liquefaction starting from top.

What pattern does Bacillus anthracis display when tested for penicillin susceptibility?

String of pearl pattern due to susceptibility/sensitivity to 10 units of penicillin on MHA.

How is the string of pearl test performed for Bacillus anthracis?

Prepare MHA media, add penicillin, inoculate the organism, and observe colonies under the microscope.

What is the Lecithinase test used for and what media is used?

Additional test to detect B. anthracis using Egg Yolk Agar (EYA) (plated media).

Is Egg Yolk Agar an isolation media?

No, it is used to detect production of lecithinase.

What is a positive result for the Lecithinase test?

Opaque zone around the colonies (milk colored).

What is the alias of Bacillus cereus?

Fried Rice Bacillus.

What is the alias of Bacillus subtilis?

Hay Bacillus.

Are Bacillus cereus and Bacillus subtilis motile or non-motile?

Both are motile.

What hemolysis do Bacillus cereus and Bacillus subtilis exhibit?

Beta-hemolytic.

What conditions are caused by Bacillus cereus toxins?

Food poisoning: Emetic form and Diarrheal form.

What symptom is frequent in the emetic form of B. cereus food poisoning?

Vomiting.

What specific toxin causes the emetic form of B. cereus food poisoning?

Cereulide.

What specific toxins cause the diarrheal form of B. cereus food poisoning?

CytK (Cytotoxin K or Hemolysin IV), HBL (Hemolysin BL), and NHE (Non-Hemolytic Enterotoxin).

What exotoxins/enterotoxins are produced by B. cereus that cause food poisoning?

Cholera-like toxin and pyogenic toxin due to consumption of contaminated rice mills.

What is the ideal/best specimen for testing Bacillus cereus?

Suspected food.

What is the ideal media and selective media for Bacillus cereus?

Ideal media: SBA; Selective media: BCM (Bacillus cereus Medium), MEYP/MYP (Mannitol Egg Yolk Polymyxin B agar), and PEMBA (Polymyxin B Egg yolk Mannitol Bromthymol Blue agar).

Is Bacillus cereus penicillin resistant or sensitive?

Penicillin resistant.

Is Bacillus subtilis a common pathogen?

No, it is a common lab contaminant and opportunistic pathogen (does not cause serious disease in healthy individuals); classified under BSL-1.

What is Bacillus subtilis a source of?

Bacitracin.

What infection does Bacillus subtilis cause in heroin addicts?

Eye infection.

Where is Bacillus subtilis a contaminant in blood processing?

Blood bank contaminant at room temperature (RT).

What is the most commonly encountered species of Bacillus in opportunistic infections?

Bacillus cereus (causing posttraumatic eye infections, endocarditis, and bacteremia).

What procedures are involved in Heat Shock Treatment for endospores?

Heat treatment at 70°C for 30 minutes or 80°C for 10 minutes to kill vegetative cells and retain spores for most Bacillus spp..

At what temperature and duration is heat shock treatment carried out for B. anthracis?

Lower temperatures: 62°C to 65°C for 15 to 20 minutes.

What risk level and organisms belong to BSL-1?

Minimal risk; Bacillus subtilis, Mycobacterium gordonae, soil microbes.

What risk level, modes of transmission, and organisms belong to BSL-2?

Moderate threat; Transmission via ingestion, percutaneous, & mucous membrane exposure (SHHESS); Staphylococcus aureus, HBV, HIV, Escherichia coli, Salmonella, Shigella.

What risk level, modes of transmission, and organisms belong to BSL-3?

High risk; Aerosol transmission/inhalation (BCsiFM); Bacillus anthracis, C. burnetii, Francisella tularensis, M. tuberculosis, Fungi (H. capsulatum, C. immitis).

What risk level and organism belong to BSL-4?

Extreme risk (life-threatening disease); Ebola virus.

What organism is used as a biological indicator for autoclaves?

Bacillus stearothermophilus.

What is the principle, ideal temperature, duration, and pressure for autoclaving monitored by B. stearothermophilus?

Principle: Steam under pressure; 121°C for 15-30 minutes or 15 psi.

What condition does Bacillus stearothermophilus cause in food spoilage?

Flat sour spoilage.

What appearance does Bacillus anthracis show on 5% SBA?

Medium-large, gray, flat, irregular with swirling projections ("Medusa head"); nonhemolytic.

What appearance do Bacillus cereus and Bacillus thuringiensis show on 5% SBA?

Large, feathery, spreading; beta-hemolytic.

What appearance does Bacillus mycoides show on 5% SBA?

Rhizoid colony that resembles a fungus; weakly beta-hemolytic.

What appearance does Bacillus megaterium show on 5% SBA?

Large, convex, entire, moist; nonhemolytic.

What appearance does Bacillus licheniformis show on 5% SBA?

Large blister colony; becomes opaque with dull to rough surface with age; beta-hemolytic.

What appearance does Bacillus pumilus show on 5% SBA?

Large, moist, blister colony; may be beta-hemolytic.

What appearance does Bacillus subtilis show on 5% SBA?

Large, flat, dull, with ground-glass appearance; may be pigmented (pink, yellow, orange, or brown); may be beta-hemolytic.

What are the characteristics of Bacillus mycoides on 5% SBA?

Produces rhizoid colonies appearing like fungus.

What is the commercial use of Bacillus thuringiensis?

Larvicidal; made commercially available as a component of pesticides/insecticides.

What differentiate Bacillus anthracis from Bacillus cereus regarding Hemolysis on SBA?

B. anthracis is gamma (-) hemolytic; B. cereus is beta (+) hemolytic.

What differentiate Bacillus anthracis from Bacillus cereus regarding Motility?

B. anthracis is non-motile (-); B. cereus is motile (+).

What differentiate Bacillus anthracis from Bacillus cereus regarding Penicillin susceptibility?

B. anthracis is Sensitive (S); B. cereus is Resistant (R).

What differentiate Bacillus anthracis from Bacillus cereus regarding Lecithinase production?

B. anthracis is (+); B. cereus is (+).

What differentiate Bacillus anthracis from Bacillus cereus regarding Fermentation of salicin?

B. anthracis is (-); B. cereus is (+/-).

What differentiate Bacillus anthracis from Bacillus cereus regarding Growth in penicillin (10 U/mL) agar?

B. anthracis is (-); B. cereus is (+).

What differentiate Bacillus anthracis from Bacillus cereus regarding String of pearl reaction?

B. anthracis is (+); B. cereus is (-).

What differentiate Bacillus anthracis from Bacillus cereus regarding Gelatin hydrolysis?

B. anthracis is (-); B. cereus is (+).

What differentiate Bacillus anthracis from Bacillus cereus regarding Growth on phenylethyl alcohol agar?

B. anthracis is (-); B. cereus is (+).