Gram positive rods

• Bacillus

  • B.anthracis -> anthrax, bioterrorism

  • B.cereus -> food poisoning (rice)

• Clostridium

  • C.tetani -> tetanus

  • C.botulinum -> botulismus

  • C.perfringens -> gas gangrene, food poisoning

  • C.difficile -> antibiotic assoc. diarrhea

• Corynebacterium

• Listeria

• Gardnerella

All aerobic except Clostridium (anaerobic)

Spores: Bacillus & Clostridium

Exotoxins: Bacillus & Clostridium & Corynebacterium

• sterilization at 121°C more than 15 minutes

• sporicidal disinfections

Antibiotics ineffective because there is only low metabolism & coat of the spore impermeable for antibiotics

• don´t stain with Gramstaining

• hollow structures in bacteria

  • sometimes no spores in clinical samples bc already activated

Clostridium tetani (Tetanus)

Clostridium perfringes (Gas gangrene)

Bacillus anthracis

Bacillus cereus

• blood agar culture -> no hemolysis (gamma)

  -> aerobic condition

• polypeptide capsule with poly D glutamic acid

• secretes 2 Exotoxins: Edema & lethal factor

• EF or LF (A subunit) always combined with protective antigen (B subunit)

• Edema factor (EF) -> binds to Protein antigen on cell -> EF i cell -> EF binds Clmodulin (CAD) -> active adenyl cyclase -> incr. intracellular cAMP -> more fluid in extracellular space -> edema

• Lethal factor (LF) -> cleaves MAPK (Mitogen act. phosphokinas) black eschar (necrotic lesion covered by crust)-> no cell growth

• cutaneous (trauma to skin; cut. anthrax)

• inhalation (pulm./inh. anthrax)

• ingestion (contaminated meat: GIS anthrax)

• injection (percutaneously; inj. anthrax)

• most common

• spore enters via injury (rarely insect)

• 1-7 days incubation

• 20% mortality if not treated -> with treatment survive 100%

• not communicable -> spores into lung but toxin rapid in mediastinal lymph nodes ->no transmission bc leaves lung

  -> hemorrhagic mediastinitis

• incubation 1-7 days (2months if small amount)

• 85-90% mortality ifno treatment (most deadly)

• vomiting, abdominal pain, bloody diarrhea

• incubation time 1-7 days

• mortality 50% if no treated

• due to drug usage f.e. heroine

• painless skin sore with black center after blisters/abscesses

Vesicular stage (day 5)

Eschar stage (day 12)

Ulcer stage (~2 months healed & scar)

• Prophylaxis & treatment

  • Ciprofloxacin

  • Doxycycline (alternative)

• vaccination not effective & many doses

• sterilization 120°C more than 15 min

• 2 hours disinfectant application

• Orf ecthyma contagiosum

  • viral disease

  • self-limited & spontaneous resolution in 4-8 weeks

Bacillus cereus

spores on grains when too much at room temperature -> germinate when repeated

• secretes 2 exotoxins

  1. similar fct to cholera (watery diarrhea)

  2. similar fct to Staphylococcal enterotoxin (super antigen)

• 2 syndromes

  • short incubation period (4h): nausea & vomiting

  • long incubation period (18h): watery nonbloody diarrhea

• no lab diagnosis

• prevent by safe food consideration

• symptomatic treatment

• Tetanus

• spores in soil; also when contaminated umbilicus or circumcision wound (neonatal tetanus)

• Exotoxin: Tetanospasmin

• carried intraaxonally to the CNS -> Blocks release of inhibitory mediators at the spinal synapses (glycine and GABA)

• results in muscle spasms, lockjaw, paralysis (majority spastic)

• Microscopy: terminal spore-tennis racket shape

  No culture

• Tetanus immunoglobulin TIG -> neutralizes

• prevention: Tetanus toxoid vaccine; clean & contaminate wound

• Clostridium botulinum -> Botulismus

• high risk: green beans, mushrooms, smoked fish

• prevention: sterilize cans, sufficient cooking

• Botulinum toxin = Protease

  -> blocks release of acetylcholine by cleaving needed proteins

• Paralysis, descending weakness, diplopia (double seeing)

• Dysphagia (swallowing pain)

• No fever

8 types

A B E most common human illness

A used for botox

• wound botulismus

  • due to injecting drugs -> skin popping

• infant botulismus

  • spores in honey dangerously for children <1

• no culture

• test uneatened food & patiens serum

• Food industry: mouse protection test

• treat with Antitoxin & Respiratory support

• Gas gangrene or food poisoning

• spores in soil, due to war, accidents, septic abortions

Alpha toxin (lecithinase) damages cell memebranes (also erthrocytes -> hemolysis) -> produce gas in tissues -> myonecrosis

• pain, edena, crepitation (crackling sound when palpating wound due to gas), hemolysis, jaundice, death

• Blood agar culture: Gram positive bacilli (α and β hemolysis)

• Treatment immediately when suspected bc risk of death

  • Wound debridement

  • Penicillin G

  • Hyperbaric oxygen

• 8-16 hr incubation period (Watery diarrhea, Cramp, Vomiting)

• No lab diagnosis, just symptomatic treatment

• Resolves in 24h

• pseudomembraneous colitis

  -> antibiotic assoc. nosocomial diarrhea (often during hospitalization)

• non-bloody diarrhea, fever, abdominal cramp, toxic megacolon

• dispiosis in microbiota due to antibiotic -> C. difficile survives & multiplies -> secretes 2 exotoxins

both glucosyl-transferase

1. Exotoxin A: Enterotoxin (potent neutrophil chemoattractant)

2. Exotoxin B: Cytotoxin (depolymerization of actin ->disrupt cytoskeleton -> death of enterocytes)

• disrupt epithelial-cell barrier

High risk: Clindamycin, Ampicillin, Cephalosporins, Fluoroquinolones, Amoxicillin-cotrimoxazole

Medium risk: Macrolides, Tetracyclines

• toxin detection

  • EIA (Enzyme immunoassay) for exotoxins

  • EIA stool antigen detection

  • PCR toxic gene DNA detection

  • cytotoxicity assay

  • colonoscopy

• Fluid replacement

• remove colon in life threatening cases

• fecal transplantation (rare)

• stop causative antibiotic and switch to f.e. Vancomycin, Methronidazol, Fidaxomycin

  • those still have low risk for causing disease