Medical Micro Bio Gram Positive

What type of bacteria is Clostridium botulinum?

Gram-positive, anaerobic, spore-forming rod

What disease does Clostridium botulinum cause?

Botulism

What is the major virulence factor of Clostridium botulinum?

Botulinum neurotoxin

What is the mechanism of botulinum toxin?

Blocks acetylcholine (ACh) release at the neuromuscular junction

What type of paralysis does botulism cause?

Flaccid paralysis

What is the classic progression of paralysis in botulism?

Descending paralysis

How is Clostridium botulinum transmitted?

Improperly canned foods, preserved foods, wound contamination, honey in infants

What food is associated with infant botulism?

Honey

What condition is associated with infant botulism?

Floppy baby syndrome

What are the signs and symptoms of botulism?

Blurred vision, diplopia, ptosis, dysphagia, weakness, respiratory failure

How is botulism diagnosed?

Clinical symptoms + toxin detection in serum, stool, or food

How is botulism treated?

Antitoxin + respiratory support

How is botulism prevented?

Proper food preservation and avoiding honey under age 1

What is the classic exam clue for botulism?

Honey + floppy baby OR canned foods + descending paralysis

Which neurotransmitter is blocked in botulism?

Acetylcholine (ACh)

What type of bacteria is Clostridium tetani?

Gram-positive, anaerobic, spore-forming rod

What disease does Clostridium tetani cause?

Tetanus

What is the virulence factor of Clostridium tetani?

Tetanospasmin toxin

What is the mechanism of tetanospasmin?

Blocks inhibitory neurotransmitters GABA and glycine

What type of paralysis does tetanus cause?

Spastic paralysis

Where are Clostridium tetani spores commonly found?

Soil, dust, and animal feces

How is Clostridium tetani transmitted?

Puncture wounds, contaminated wounds, burns, surgery

What are the signs and symptoms of tetanus?

Lockjaw (trismus), muscle rigidity, spasms, dysphagia, risus sardonicus, opisthotonos

What is trismus?

Lockjaw due to jaw muscle spasms

What is risus sardonicus?

Fixed grin from facial muscle spasm

What is opisthotonos?

Severe arching of the back from muscle spasms

How is tetanus diagnosed?

Clinical diagnosis

How is tetanus treated?

Tetanus immune globulin (TIG), metronidazole, wound care, supportive care

How is tetanus prevented?

Tdap/DTaP vaccination and boosters every 10 years

What is the classic exam clue for tetanus?

Rusty nail + lockjaw + spastic paralysis

What are the four types of tetanus?

Generalized, localized, cephalic, neonatal

What is generalized tetanus?

Most common form with widespread muscle spasms

What is localized tetanus?

Muscle rigidity near wound site

What is cephalic tetanus?

Rare form affecting cranial nerves

What is neonatal tetanus?

Tetanus in newborns due to contaminated umbilical stump

What type of bacteria is Clostridium perfringens?

Gram-positive, anaerobic, spore-forming rod

What diseases does Clostridium perfringens cause?

Gas gangrene (myonecrosis) and food poisoning

What is the major virulence factor of Clostridium perfringens?

Alpha toxin (lecithinase)

What does alpha toxin do?

Destroys cell membranes causing tissue necrosis

How is Clostridium perfringens transmitted?

Traumatic wounds, crush injuries, surgery, contaminated food

What are the signs and symptoms of gas gangrene?

Severe pain, swelling, tissue necrosis, foul odor, crepitus

What is crepitus?

Crackling sensation from gas in tissues

What food is associated with C. perfringens food poisoning?

Reheated meats and gravy

How is C. perfringens diagnosed?

Clinical symptoms + culture/gram stain

How is C. perfringens treated?

Surgical debridement + penicillin

What is the classic exam clue for C. perfringens?

Gas in tissue + crepitus

What type of bacteria is Clostridium difficile?

Gram-positive, anaerobic, spore-forming rod

What disease does Clostridium difficile cause?

Pseudomembranous colitis

What are the virulence factors of Clostridium difficile?

Toxin A and Toxin B

How does C. difficile infection occur?

Antibiotic use disrupts normal gut flora allowing overgrowth

What are risk factors for C. difficile?

Recent antibiotic use, hospitalization, elderly age

What are the signs and symptoms of C. difficile infection?

Watery diarrhea, abdominal pain, fever, pseudomembranes

What are pseudomembranes?

Yellow inflammatory plaques in the colon

How is C. difficile diagnosed?

Stool toxin testing

How is C. difficile treated?

Oral vancomycin or fidaxomicin

How is C. difficile prevented?

Hand hygiene and antibiotic stewardship

What is the classic exam clue for C. difficile?

Antibiotics followed by severe diarrhea

What type of bacteria is Bacillus anthracis?

Gram-positive, aerobic, spore-forming rod

What disease does Bacillus anthracis cause?

Anthrax

What are the major virulence factors of Bacillus anthracis?

Anthrax toxin and capsule

What is unique about the capsule of Bacillus anthracis?

Poly-D-glutamate capsule

What are the three forms of anthrax?

Cutaneous, inhalational, gastrointestinal

What is cutaneous anthrax?

Most common form with black eschar lesion

What are the signs and symptoms of inhalational anthrax?

Fever, cough, chest pain, widened mediastinum

What are the signs and symptoms of gastrointestinal anthrax?

Abdominal pain, vomiting, bloody diarrhea

How is Bacillus anthracis transmitted?

Animal products, inhaled spores, contaminated meat

How is anthrax diagnosed?

Culture, PCR, imaging

How is anthrax treated?

Ciprofloxacin or doxycycline

What is the classic exam clue for anthrax?

Black eschar OR widened mediastinum

What type of bacteria is Staphylococcus aureus?

Gram-positive cocci in clusters

What are the identifying characteristics of Staphylococcus aureus?

Catalase-positive, coagulase-positive, beta-hemolytic

What diseases does Staphylococcus aureus cause?

Skin and soft tissue infections, pneumonia, bacteremia, endocarditis, osteomyelitis, food poisoning, toxic shock syndrome

What are the major virulence factors of Staphylococcus aureus?

Protein A, coagulase, hemolysins, leukocidins, enterotoxins, TSST-1, exfoliative toxin

What does Protein A do?

Binds Fc portion of IgG to avoid phagocytosis

What does coagulase do?

Converts fibrinogen to fibrin to protect bacteria

What are the symptoms of S. aureus food poisoning?

Rapid vomiting after eating contaminated food

What foods are associated with S. aureus food poisoning?

Cream-filled pastries, mayonnaise-based foods, potato salad

What are the signs and symptoms of toxic shock syndrome?

Fever, rash, hypotension, multiorgan involvement

What toxin causes scalded skin syndrome?

Exfoliative toxin

What antibiotic-resistant strain of S. aureus is high-yield?

MRSA

How is S. aureus diagnosed?

Culture, gram stain, coagulase testing

How is S. aureus treated?

MSSA: nafcillin/oxacillin; MRSA: vancomycin

How is S. aureus prevented?

Hand hygiene and wound care

What is the classic exam clue for S. aureus?

Abscesses + MRSA + toxic shock

What type of bacteria is Staphylococcus epidermidis?

Gram-positive cocci in clusters

What are the identifying characteristics of S. epidermidis?

Catalase-positive, coagulase-negative

What diseases does S. epidermidis cause?

Prosthetic joint infections, catheter infections, prosthetic valve endocarditis

What is the major virulence factor of S. epidermidis?

Biofilm formation

What does the biofilm of S. epidermidis do?

Allows bacteria to stick to medical devices and resist antibiotics

What is S. epidermidis commonly associated with?

Indwelling catheters and implanted medical devices

How is S. epidermidis diagnosed?

Culture

How is S. epidermidis treated?

Vancomycin + removal of infected device

What is the classic exam clue for S. epidermidis?

Prosthetic device infection

What type of bacteria is Streptococcus pyogenes?

Gram-positive cocci in chains

What group is Streptococcus pyogenes?

Group A beta-hemolytic streptococcus

What diseases does Streptococcus pyogenes cause?

Pharyngitis, impetigo, cellulitis, erysipelas, necrotizing fasciitis, scarlet fever, rheumatic fever, post-strep glomerulonephritis

What are the virulence factors of S. pyogenes?

M protein, streptolysins, pyrogenic exotoxins

What does M protein do?

Prevents phagocytosis

What are signs and symptoms of scarlet fever?

Sandpaper rash + strawberry tongue

What is necrotizing fasciitis?

Flesh-eating disease