Other gram positives Flashcards
1
Q
Clostridium all share these features
A
- All Gpos rods
- all form spores
- all are obligate anaerobes
- All form toxins
2
Q
Species of Clostridium to know
A
- C. tetani (tetanus)
- C. botulinum (botulism)
- C. perfringens (wound infections, food poisoning)
- C. difficile (diarrhea after antibiotic use)
3
Q
C. tetani features
A
- spores found in soil
- enter the body from a penetrating injury (nail/splinter)
- spores germinate into bacteria
- produce tetanus toxin (tetanospasmin)
- Travels to spinal cord
- Blocks glycine and GABA release from Renshaw cells (inhibitory spinal cord interneurons)
- symptoms
- Spasms
- Muscle contractions
- Rigidity
- Lockjaw (trismus)
- Risus sardonicus (forced grin due to spastic facial muscles)
4
Q
Tetanus Tx
A
- Wound debridement
- Metronidazole
- Tetanus immune-globulin (binds circulating toxin)
- Benzos or neuromuscular blockers until the toxin wears off
- Tetanus toxoid is used for vaccination
5
Q
C. botulinum features
A
- Ubiquitous organism
- Vegetables, fruits, seafood, soil
- Creates heat-resistant spores (up to 100oC)
- produces Botulinum toxin
- works at neuromuscular junctions and prevents ACh release resulting in floppy paralysis
- there are many different variants of the toxin and some are carried by bacteriophages
6
Q
Botulism types
A
- Food (toxin ingestion; usually adults)
- Infant (spores)
- Wound (Bacterial growth)
7
Q
Preformed toxin ingestion Botulism
A
- usually adults
- undercooked food
- canned food: anaerobic environment promotes growth
- watch for multiple sick adults after a meal
8
Q
Infant Botulism
A
- ingestion of spores -> growth in infant intestine
- Watch for contaminated honey
9
Q
Wound Botulism
A
C. botulinum bacterial growth in a wound
10
Q
Botulism features
A
- symptoms appear 12-48 hours post-ingestion
- Diplopia
- Dysphagia
- Dysphonia
- Dx
- often clinical
- spores and toxin are sometimes detected in stool
- Tx:
- Antitoxin blocks circulating toxin
- cannot block the toxin already in nerves
- supportive care until toxin washout
11
Q
C. perfringens features
A
- Widespread in nature, especially in soil
- Infects dirty wounds & causes food poisoning
- Causes Gas Gangrene (Clostridial myonecrosis)
- traumatic wound with vascular compromise
- Favorable environment for anaerobic growth
- Produces Alpha toxin
- destroys muscle tissue and causes hemolysis
- Phopholipase that acts on lecithin (lecithinase)
- Degrades phospholipids in cell membranes
12
Q
What is Alpha toxin
A
a toxin produced by Clostridium perfringens that is a phopholipase that acts on lecithin (is a lecithinase) and degrades phospholipids in cell membranes
13
Q
Gas gangrene
A
- caused by C. perfringens
- Alpha toxin
- severe pain at injury site within 24 hours
- skin tense and tender
- systemic symptoms
- fever
- hypotension
- shock
- Dx
- gas at injury site on imaging
- crepitus
- Tx
- surgical debridement
- Broad spectrum antibiotics
14
Q
C. perfringens food poisoning
A
- usually undercooked meats
- spores ingested so delay of (8-22 hours) before watery diarrhea
- Contrast with S. aureus/B cereus (preformed toxins) so symptoms happen much more quickly (3-6 hours)
15
Q
Features of C. difficile
A
- Ubiquitous spores in nature including the soil
- ingestion not harmful with normal GI flora
- colonic flora prevent overgrowth of C. diff
- Causes antibiotic-associated coolitis
- antibiotics alter the normal gut flora resulting in a favorable environment for C. diff growth
16
Q
Pseudomembranous colitis
A
- Caused by opportunistic pathogen C. difficile
- antibiotics disrupt normal gut flora allowing C. difficile to grow
- Not invasive infection but is due to two toxins that bind to enterocytes and internalize them
- Toxin A: Enterrotoxin -> watery diarrhea
- Toxin B (10x more potent than toxin A): Cytotoxin -> cell necrosis/fibrin deposition
- Toxins destroy the cytoskeleton of GI cells -> pseudomembrane
- Massive watery diarrhea
- endoscopy: pseudomembrane (white-yellow plaque), mucosal ulcerations, fibrin, inflammatory cells
- Dx: Stool detection of Toxin A and B
17
Q
Pseudomembranous colitis AKA
A
C. diff colitis
18
Q
Treatment of Pseudomembranous colitis
A
- Metronidazole
- ORAL vancomycin
- other therapy for severe disease
- Surgery
- Stool transplant
19
Q
Corynebacterium diphtheria
A
- Gpos non-motile non-spore forming curved rod with chinese character distribution
- Causes diptheria
- Produces Exotoxin
- diptheria exotoxin is not from part of the bacterial genome but is carried by a bacteriophage (lysogenic phage -> incorporates DNA to the bacteria)
- inactivates elongation factor 2 (EF-2) by adding ADP-ribosyl
- EF-2 is necessary for protein synthesis (translation)
- Unique lab diagnostic techniques
20
Q
Corynebacterium diphtheria culture media
A
- Loeffler’s or Tinsdale (Tellurite plate)
- black colonies on Tinsdale media
- Metachromatic (blue/red) granules on Loeffler’s media
21
Q
Corynebacterium diphtheria diagnostic test
A
- Elek test for toxin detection
- antitoxin-impregnanted filter paper under agar
- bacterial toxin precipitates and can be visualized
22
Q
Diphtheria
A
- caused by Corynebacterium diphtheria
- 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)
- Incidence is rare in the modern era due to vaccination with toxoid
23
Q
Diphtheria Treatment
A
- Penicillin
- Diphtheria antitoxin (passive immunization)
- Diphtheria toxoid (active immunization)
24
Q
Listeria features
A
- 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”)
- tends to infect poor cell-mediated immunity
- neonates
- HIV
- organ transplant
- In adults, often from contaminated food
- Undercooked meat, unwashed vegetables
- unpasteurized cheese/milk
- Likes cold temperatures
- neonates transplacental or transvaginal
25
Q
Listeria illnesses
A
- Gastroenteritis
- NVD
- usually self-limited
- Meningitis
- elderly or newborns
- Infection in pregnancy
- bacteremia in 3rd trimester
- flu-like illness (fever, chills)
- often resolves without treatment
- Rarely causes fatal demise or newborn infection
26
Q
Granulomatosis infantiseptica
A
- 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 inflammation
- Chorioamnionitis
- Villitis
- Abscess formation
27
Q
Bacillus group bacteria
A
- Bacillus anthracis
- Bacillus cereus
28
Q
Bacillus anthracis features
A
- only bacteria with polypeptide capsule
- most are polysaccharide
- contains D-glutamate
- Limits/prevents phagocytosis
- Found in soil
- Infects cattle, sheep, horses and humans
- farm workers are at risk
- spores can be used in bioterrorism
- produces 2 toxins
- Edema toxin
- Lethal toxin
29
Q
Bacillus anthracis toxins
A
- Edema toxin
- Activates adenylate cyclase
- increases cAMP-> fluid secretion
- Lethal toxin
- Protease
- inhibits cell signaling
- Causes apoptosis
30
Q
Anthrax cutaneous disease
A
- spores eter skin through cuts/abrasions
- vegetate -> bacteria grows
- painless black ulcers forms
- can progress to bacteremia and death
- Edema surrounds black ulcer from edema factor
- Tx
- Ciprofloxacin
- Doxycycline
- Clindamycin
31
Q
Anthrax pulmonary disease
A
- Pulmonary disease
- “woolsorter’s disease”
- Inhalation of spores
- Flu like symptoms that rapidly progress
- pulmonary hemorrhage, mediastinitis, shock, death
- Tx
- Multidrug regimen, antitoxin
- Imaging
- Wide mediastinum (aortic dissection causes this also but would have different symptoms)
32
Q
Bacillus cereus features
A
- Food poisoning from enterotoxins
- classically from undercooked or reheated rice
- bacteria frequently present in undercooked rice
- heat-resistant spores may survive cooking
- cooked rice at room temperature may allow to multiply
- “reheated rice syndrome”
33
Q
Types of B. cereus food poisoning
A
- Emetic type
- direct ingestion of toxin: Cereulide
- abdominal cramps, NV (rarely diarrhea)
- 1-5 hours post-ingestion
- classically occurs in rice dishes
- Diarrheal type
- Abdominal cramps and diarrhea (not vomiting)
- 8 to 16 hours after ingestion
- caused by eating several enterotoxins
- Toxins are heat labile
- cooking food reduces risk of illness
- often from meats, vegetables and sauces
34
Q
Actinomyces features
A
- 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 preceeded by dental work/orofacial trauma
- facial mass present on exam
- often yellow center (yellow “sulfur” granules)
- often draining pus
- Treatment:
- Penicillin +/- drainage
35
Q
Bacteria to know that resemble fungi
A
- Nocardia
- Actinomyces
36
Q
Nocardia features
A
- Branching filamentous (like actinomyces)
- acid-fast
- produces urease (can be used to identify bacteria)
- Obligate aerobe (loves lungs)
- found in soil
37
Q
Nocardia illnesses
A
- Pneumonia
- Skin infection
- brain abscesses
- Bacteremia
38
Q
Nocardia pneumonia
A
- immunocompromised pts
- inhalation of bacteria
- radiological findings
- nodules
- masses
- infiltrates
- lobar consolidation
- pleural effusions
- Tx
- TMP-SMX
39
Q
Nocardia Skin infection
A
- Immunocompetent pts
- often invades during gardening or farming
- manifestations
- ulcers
- cellulitis
- nodules
- abscesses
- Treatment
- TMP-SMX
40
Q
Nocardia drug of choice
A
TMP-SMX
