Internal Medicine_Infectious Diseases_3 Flashcards
Bacteria_Bacillus spp., Gardnerella
What is the morphology of Bacillus anthracis?
It is a gram-positive rod that grows in chains.
What type of capsule does Bacillus anthracis have?
A capsule made of poly-γ-D-glutamate (polypeptide).
What is the hallmark lesion of cutaneous anthrax?
A black eschar (necrotic lesion) surrounded by an erythematous ring.
The lesion is painless.
How does Bacillus anthracis appear on blood agar?
It does not undergo hemolysis (gamma-hemolytic).
What are the two major exotoxins produced by Bacillus anthracis?
Edema factor (EF):
The edema factor (EF) exotoxin of Bacillus anthracis is a calmodulin-dependent adenylate cyclase that converts ATP into CAMP, contributing to the establishment of infections. The adenylate cyclase increases intracellular cAMP, which leads to edema.
Lethal factor (LF):
The lethal factor (LF) exotoxin of Bacillus anthracis acts as a protease that targets mitogen-activated protein kinase (MAPK), resulting in the disruption of cellular signaling pathways and impairment of the host’s immune response, causing tissue necrosis.
What is “woolsorters’ disease”?
Pulmonary anthrax caused by inhalation of spores, historically associated with wool processing.
Historically, wool sorters were at risk of contracting pulmonary anthrax, also known as “woolsorters’ disease”, through inhalation of spores present in animal wool, although this transmission mode is now rare in developed nations.
What radiological finding is associated with inhalational anthrax?
Fever, pulmonary hemorrhage, mediastinitis, shock, and meningitis.
A widened mediastinum on chest X-ray will indicate hemorrhagic mediastinitis.
What is the standard treatment for anthrax?
Fluoroquinolones (e.g., ciprofloxacinor levofloxacin) or doxycycline.
Anthrax antitoxin.
Supportive care.
What is Bacillus cereus commonly associated with?
Food poisoning, especially from reheated rice.
Patients will experience emesis and diarrhea.
What is the pathogenesis of Bacillus cereus food poisoning?
Pre-formed enterotoxins in reheated food cause early-onset symptoms (1–6 hours after ingestion). Patients will experience Nausea, Vomiting, Diarrhea, and Abdominal cramps.
Bacillus cereus infection is classically associated with reheated rice (warm temperatures → spore germination → preformed enterotoxin production → early onset food poisoning).
What environmental feature makes Bacillus species resilient?
They are spore-forming, allowing survival under extreme conditions.
Are Bacillus species aerobic or anaerobic?
They are aerobic or facultative anaerobic.
What skin manifestation is associated with Bacillus?
Painless ulcer with a black eschar.
What is the treatment approach for Bacillus cereus
Supportive.
This is a self-limited disease.
What type of bacterium is Gardnerella vaginalis?
A gram-variable coccobacillus (stains either gram-positive or gram-negative).
What are clue cells, and how are they identified?
Vaginal epithelial cells coated with Gardnerella vaginalis bacteria, seen under microscopy in a wet mount.
