Practice Test for Gram Pos. Bacilli

What is the common name for Bacillus anthracis?

Anthrax bacillus.

What is the virulence factor of Bacillus anthracis?

D-glutamate capsule and the production of exotoxins (lethal factor, edema factor, and protective antigen).

How is Bacillus anthracis transmitted?

It is transmitted through contact with infected animals or animal products.

What diseases are caused by Bacillus anthracis?

Anthrax, including cutaneous anthrax, pulmonary anthrax (Ragpicker's disease), and intestinal anthrax.

What are the laboratory diagnostics for Bacillus anthracis?

String of pearl appearance on MHE agar, Gram stain showing boxcar morphology, and Medusa head colonies on BAP.

What are the two types of toxins produced by Bacillus cereus?

Enterotoxin and pyogenic toxin.

What are the two forms of disease caused by Bacillus cereus?

Diarrheal type (watery diarrhea) and emetic type (vomiting after consuming fried rice).

What is a key feature of Bacillus subtilis in the lab?

It is a common laboratory contaminant and the source of Bacitracin.

Which bacterium is known as the gas gangrene bacillus?

Clostridium perfringens.

What test is used to detect Clostridium perfringens' alpha toxin?

Lecithinase test (Naegler Reaction).

What are the diseases caused by Clostridium perfringens?

Food poisoning, gas gangrene, and myonecrosis.

What is the virulence factor of Clostridium tetani?

Tetanospasmin (neurotoxin causing spastic paralysis).

What is the common name for Clostridium tetani?

Tetanus bacillus or drumstick bacillus.

What disease is caused by Clostridium botulinum?

Botulism, which causes flaccid paralysis.

What is the common source of Clostridium botulinum infection?

Ingestion of preformed toxin in improperly processed canned goods.

What is a key diagnostic test for Clostridium difficile?

Cytotoxin detection and culture on CCFA agar, where colonies produce a horse stable odor.

What are the virulence factors of Clostridium difficile?

Toxin A (enterotoxin) and Toxin B (cytotoxin).

What are the main types of Clostridium infections?

Histotoxic (e.g., gas gangrene), neurotoxic (e.g., tetanus and botulism), and toxigenic enteric (e.g., Clostridium difficile infections).

What is the diagnostic test used for Clostridium perfringens?

Reverse CAMP test, showing enhanced hemolysis as an arrowhead zone of beta hemolysis.

What medium is used to culture Clostridium perfringens?

Duncan and Strong medium, known for producing spores and starch fermentation.

What disease does Clostridium tetani cause?

Tetanus, which includes risus sardonicus (sardonic smile) and muscle spasms.

What is the laboratory diagnosis for Clostridium botulinum?

Laboratory confirmation is done by demonstrating the toxin in stool, food, or wound, along with culturing the organism.

What are the common symptoms of botulism?

Flaccid paralysis, difficulty breathing, and muscle weakness, often due to the ingestion of preformed toxins.

How is Clostridium difficile acquired?

It is commonly acquired in hospitals, particularly by individuals receiving antibiotics that disrupt normal gut flora.

What is the key characteristic of Clostridium tetani spores?

The spores are terminally located, giving the bacterium a "drumstick" or "tennis racquet" appearance.

What medium is used to detect Clostridium difficile in culture?

Cycloserine Cefoxitin Fructose Agar (CCFA), which develops colonies with a horse stable odor.

What condition is associated with Clostridium difficile infection?

Pseudomembranous colitis, often caused by antibiotic treatment disrupting the gut flora.

What is the treatment option for severe gas gangrene caused by Clostridium perfringens?

Hyperbaric oxygen therapy, which increases oxygen levels to inhibit anaerobic bacterial growth.

What is the common name for Bacillus cereus and the associated disease?

Known as the "Fried Rice Bacillus," it causes food poisoning, particularly after consuming reheated fried rice.

How does Bacillus anthracis appear on plated media?

It forms colonies with a "Medusa head" or "lion head" appearance, and is non-hemolytic on blood agar.

What is the main clinical feature of cutaneous anthrax?

The formation of a "black eschar" at the site of infection, which is a black necrotic lesion.

What is the difference between the diarrheal and emetic forms of Bacillus cereus food poisoning?

The diarrheal form causes watery diarrhea without fever, while the emetic form causes profuse vomiting after ingesting reheated fried rice.

What is the virulence factor of Clostridium perfringens responsible for gas gangrene?

Alpha toxin, which causes tissue necrosis and gas production in muscle tissues.

How is Clostridium tetani neurotoxin (tetanospasmin) associated with its clinical symptoms?

Tetanospasmin blocks the release of neurotransmitters, leading to spastic paralysis, muscle rigidity, and characteristic muscle spasms.

What type of paralysis does Clostridium botulinum cause?

Flaccid paralysis, which is the opposite of the spastic paralysis caused by tetanus.

How does Clostridium botulinum toxin act on the body?

The toxin inhibits acetylcholine release at neuromuscular junctions, leading to muscle weakness and paralysis.

What are the characteristics of Clostridium difficile colonies on BAP (Blood Agar Plate)?

Colonies exhibit fluorescence under ultraviolet light and have a chartreuse (yellow-green) color.

What is the laboratory method used to confirm the presence of Clostridium difficile toxins in a patient sample?

Cytotoxin detection assay from freshly passed stool, which identifies Toxin A and Toxin B.

What specific feature distinguishes Bacillus anthracis spores?

Bacillus anthracis spores are centrally located and can remain viable in the soil and animal products for decades.

What laboratory technique is used to differentiate Bacillus species from Clostridium species?

The catalase test: Bacillus is catalase-positive, while Clostridium is catalase-negative.

What is the typical morphology of Bacillus anthracis on Gram-stained smears?

Bacillus anthracis has a boxcar-like morphology due to its square-ended bacilli, giving a "bamboo rod" appearance.

What is a key diagnostic test for Clostridium tetani?

Gelatinase test, which is positive for Clostridium tetani.

What is the preferred medium for culturing Clostridium perfringens?

Egg Yolk Agar (EYA), where it shows positive lecithinase activity, indicated by an opaque zone around the colonies.

What special staining method is used to visualize Bacillus anthracis spores?

The McFadyean's stain, used for identifying Bacillus anthracis in tissue samples and cultures.

What clinical condition is caused by Clostridium botulinum in infants?

Infant botulism, also known as "floppy baby syndrome," caused by the growth of C. botulinum in the intestines of infants.

What is the appearance of Clostridium tetani on culture media?

Initially alpha-hemolytic, C. tetani becomes beta-hemolytic on blood agar plates (BAP) as it grows.

How is Clostridium difficile typically treated in severe cases of infection?

Metronidazole or vancomycin is often used to treat severe Clostridium difficile infections, especially in cases of pseudomembranous colitis.

What condition is caused by Clostridium botulinum through foodborne infection?

Botulism, which occurs after consuming food contaminated with botulinum toxin, particularly improperly canned foods.