Other Gram Positives

Question 1

Family of Clostridium bacteria are all _(3 characteristics)

Answer 1

All form spores • All obligate anaerobes • All form toxins

Question 2

Clostridium tetani

Classic scenario & symptoms:

what does it do and how?

Answer 2

Classic scenario: barefoot on rusty/dirty nail or splinter

Classic symptoms • Lockjaw (trismus) • Risus sardonicus (forced grin due to spastic facial muscles)

Tetanus toxin produced (tetanospasmin) • Travels to spinal cord • Blocks glycine and GABA release by inhibitory neurons

“Renshaw cells:” inhibitory spinal cord interneurons

Question 3

Clostridium tetani Treatment & Treatment

Answer 3

Treatment for tetanus

Wound debridement • Metronidazole • Tetanus immune globulin (binds circulating toxin) • Benzos or neuromuscular blockers until toxin wears off

Tetanus toxoid used for vaccination

Question 4

Clostridium botulinum

spores are:

toxin does what?

Answer 4

Heat-resistant spores

Botulinum toxin • Works at neuromuscular junctions • Prevents Ach release (no muscle contraction) • Result: Floppy muscles (flaccid paralysis)

gene for toxin carried by bacteriophages

Question 5

3 types of Botulism

symptoms:

Answer 5

Food (toxin ingestion; usually adults)

Undercooked food • Canned food: anaerobic environment promotes growth • Watch for multiple sick adults after a meal

Infant (spores) • Ingestion of spores → growth in infant intestine • Watch for contaminated honey!

Wound (bacterial growth) • Infection with C. botulinum

Symptoms: 3 D’s • Diplopia, dysphagia, dysphonia

Question 6

Botulism Treatment & diagnosis

Answer 6

Diagnosis: • Often clinical • Spores and toxins sometimes detected in stool

Treatment: • Antitoxin blocks circulating toxin • Cannot block toxin already in nerves • Supportive care → toxin washout

Question 7

Clostridium perfringens

causes:

toxin:

Answer 7

Infects dirty wounds (gas gangrene) & causes food poisoning (undercooked meats) • Spores ingested → produce toxin • Late onset (8-22hrs) watery diarrhea • Contrast with S. aureus/B. cereus (preformed toxin) which also produce watery diarrhea but much quicker onset

Alpha toxin

Destroys muscle tissue and causes hemolysis • Phospholipase that acts on lecithin (lecithinase) • Degrades phospholipids in cell membranes

Question 8

Clostridium difficile

what does it do and when?

Answer 8

Ubiquitous spores in nature including soil

Ingestion not harmful with normal GI flora because Colonic flora prevent overgrowth of C. diff

Causes antibiotic-associated colitis.pseudomembranous colitis • Antibiotics alter normal gut flora • Favorable environment for C. diff growth

Question 9

Clostridium difficile toxin?

Answer 9

Not invasive: disease via toxins

Two toxins

Toxin A: Enterotoxin → watery diarrhea •

(more potent)**Toxin B: Cytotoxin → Cell necrosis/fibrin deposition • Both bind to GI cells and are internalized • Destroy cytoskeleton of GI cells → pseudomembrane

Question 10

Clostridium difficile colitis presentation and treatment:

Answer 10

Massive watery diarrhea • On endoscopy (rarely done): • Pseudomembrane formation (white-yellow plaques) • Mucosal ulcerations, fibrin, inflammatory cells •

Diagnosis • Stool detection of toxin A and B

Question 11

Treatment for Clostridium difficile colitis

Answer 11

Metronidazole • ORAL Vancomycin •(normally not given orally due to poor absorption but in this case thats what you want, need it to hangout for awhile to kill c diff)

Other therapy for severe, recurrent disease • Surgery • Stool transplant

Question 12

Corynebacterium diphtheria unique toxin feature:

Answer 12

Diphtheria Exotoxin

Not part of bacterial genome • Carried by β-prophage • “Lysogenic” phage → incorporates DNA into bacteria

mechanism of action: Inactivates elongation factor (EF-2) • EF-2 necessary for protein synthesis (translation) via ADP ribosylation

Question 13

Corynebacterium Features

has been referred to as:

special media:

diagnosis:

Answer 13

“Chinese character”

Special culture media required

Loeffler’s [Metachromatic (blue/red) granules] or Tinsdale (Tellurite plate) [Black colonies]

Elek test for** **toxin detection** **(for diagnosis) • Antitoxin-impregnated filter paper under agar

Bacterial toxin precipitates and can be visualized

Question 14

Diphtheria: signs/symptoms:

Absorption/dissemination of toxin can cause:

Answer 14

Sore throat, fever, lymphadenopathy

Gray-white membrane in pharynx

Absorption/dissemination of toxin can cause:

Myocarditis (heart failure, arrhythmias, heart block)

CNS disease (neuropathies)

Renal disease (renal failure)

Question 15

Diphtheria treatment:

Answer 15

Treatment (acute infection):

Penicillin • Diphtheria antitoxin (passive immunization) • Diphtheria toxoid (active immunization)

note: rare due to toxoid vaccination

Question 16

Listeria

Found in:

Facultative __ organism

whats unique about it:

Answer 16

Found in soil

Facultative intracellular organism

“Tumbling motility” • Move from cell to cell to avoid extracellular response • Polymerizes actin in cells to move (“actin rockets”)

Question 17

what does Listeria do (3 things)/who does it affect?

Answer 17

Gastroenteritis

Diarrhea, nausea, vomiting • Usually self limited • often from contaminated food • Undercooked meat, unwashed vegetables • Unpasteurized cheese/milk

Meningitis

Elderly or newborns

Infection in pregnancy

Bacteremia in 3rd trimester • Flu-like illness (fever, chills) • Often resolves without treatment • Rarely can cause fetal demise or newborn infection

likes to Multiply in cells with poor cell-mediated immunity • Neonates, HIV, organ transplant

Question 18

what is Granulomatosis Infantiseptica?

Answer 18

Listeria!

Severe in utero infection from Listeria • Disseminated abscesses and/or granulomas • Multiple organs: liver, spleen, lungs, kidneys, brain • Skin lesions (papules, ulcers) • Most babies stillborn or die soon after birth • Placenta shows distinctive inflammation • Chorioamnionitis • Villitis • Abscess formation

Question 19

Only bacteria with a polypeptide capsule?

Answer 19

Bacillus Anthracis

Most are polysaccharide • B. Anthracis capsule contains D-glutamate • Limits/prevents phagocytosis

Question 20

Bacillus Anthracis important features:

Answer 20

polypeptide capsule

Found in soil • Infects cattle, sheep, horses (and humans) • Farm workers at risk

Spores can be used as bioterrorism weapon

Produces two toxins: • Edema toxin • Lethal toxin

Question 21

Anthrax Toxins

Answer 21

Edema toxin (contains edema factor) • Mimics adenylate cyclase • Increases cAMP → fluid secretion

Lethal toxin (contains lethal factor) • Protease • Inhibits cell signaling • Causes apoptosis

Question 22

Anthrax Cutaneous disease

how does it happen, what is distinct about it and treatment?

Answer 22

Spores enter skin through cuts/abrasions →Vegetate → bacteria grows → Painless black ulcers forms** • Can progress to bacteremia and death • **Edema surrounds black ulcer from edema factor

Treatment: Ciprofloxacin, Doxycycline, Clindamycin

Question 23

Anthrax Pulmonary disease

aka

how does it happen?

symptoms?

treatment?

classic CXR finding:

Answer 23

“Woolsorters’ disease”

Inhalation of spores • Flu symptoms that rapidly progress

Pulmonary hemorrhage, mediastinitis, shock, death

Treatment: Multi-drug regimen, antitoxin

Classic CXR finding: widened mediastinum

Question 24

Bacillus Cereus: food to think about:

Answer 24

causes food poisoning from enterotoxins • Classically in undercooked/reheated rice • Heat-resistant spores may survive cooking • Cooked rice at room temperature allow bacteria to multiply • “Reheated rice syndrome”

Question 25

2 types of illness caused by Bacillus Cereus:

Answer 25

Emetic type

Direct ingestion of toxin: Cereulide

Abdominal cramps, nausea, and vomiting (rarely diarrhea) • 1 to 5 hours after ingestion • Classically occurs in rice dishes

Diarrheal type

Abdominal cramps and diarrhea (not vomiting) • 8 to 16 hours after ingestion • Caused by at several enterotoxins • Toxins are heat labile • Cooking food reduces risk of illness • Often from meats, vegetables, and sauces

Question 26

Actinomyces

where is it found?

what does it cause?

face thing to know:

treatment:

Answer 26

Normal oral flora • Also found in female genital tract

Anaerobe • Clusters into long filaments resembling fungi

Causes head/neck abscesses • In women, can cause IUD infections

Classically preceded by dental work/orofacial trauma • Facial mass present on exam • Often yellow center (yellow “sulfur” granules) • Often draining puss

Treatment: Penicillin +/- drainage

Question 27

Nocardia boring little things to know about it:

they are important because:

treatment:

Answer 27

Branching, filamentous (like Actinomyces) • Acid fast • Produces urease (can be used to identify bacteria) • Obligate aerobe (loves lungs!) • Found in soil

boring but important to know because it causes pneumonia(usually immunocompromised) and skin infections(immunocompetent) without any classic/unique signs so the giveaway will be in bugs description

treatment: TMP-SMX