2nd term lectures,_bacilli[1]


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2nd term lectures,_bacilli[1]

  1. 1. 2010-20112nd Term 2nd Semester
  2. 2. Aerobic Gram-positive spore forming bacilli: Bacillus anthracis and other Bacillus species Bacillus anthracis  Aerobic , Gram positive, Spore forming bacilli  Causes anthracis, a zoonotic disease transmitted from animals to humans Definition of Cases in anthracis diagnosticsConfirmed Case: Clinically compatible confirmed by isolation of B. anthracis based on two laboratory testsSuspected Case: Clinically compatible with one supportive lab test
  3. 3. Three forms of anthracis disease Cutaneous anthracis  Usually forms black necrotic ulcer (eschar) Inhalational anthracis  Hypoxia and dyspnea, often with radiographic evidence of mediastinal widening. Most serious Gastrointestinal anthracis Abdominal distress, usually accompanied by bloody vomiting and diarrhea, followed by fever, septicemia (poorly cooked meat.
  4. 4. Cutaneous anthracisVesicle development Day 2 Day 4 Day2 Day 6 Day 10 Mediastinal Widening and Pleural Eschar formationsEffusion on Chest X-Ray in Inhalational Anthrax
  5. 5. B. anthracis: Presumptive Identification specimen (blood, CSF, etc.) Gram Positive Isolate on SBACapsule production Madusa Head Colony NonHemolytic NonMotile Spores Gram stain Malachite green
  6. 6. B. anthracis: Confirmatory Identification Isolate Capsule DFAPhage lysis Capsule antigen Horse Bicarbonate Cell wall blood media (M’Fadyean (M’Fadyean stain Stain) India ink stain)
  7. 7. Recommended Post-exposure Prophylaxis to Prevent Inhalational Anthrax Initial Therapy DurationAdults Ciprofloxacin 60 days 500 mg PO BID OR Doxycycline 100 mg PO BIDChildren Ciprofloxacin* 60 days 10–15 mg/kg PO Q 12 hrs Change to OR amoxicillin Doxycycline: if susceptible >8 yrs and >45 kg: 100 mg PO BID >8 yrs and <45 kg: 2.2 mg/kg PO BID <8 yrs: 2.2 mg/kg PO BID *Ciprofloxacin not to exceed 1 gram daily in children Patient information sheets at www.bt.cdc.gov
  8. 8. Cutaneous Anthrax Treatment ProtocolCategory Initial Therapy (Oral) DurationAdults Ciprofloxacin 60 daysw 500 mg BID OR Doxycycline 100 mg BIDChildren Ciprofloxacin** 60 daysw 10–15 mg/kg Q 12 hrs OR Doxycycline: >8 yrs and >45 kg: 100 mg BID >8 yrs and <45 kg: 2.2 mg/kg BID <8 yrs: 2.2 mg/kg BID **Ciprofloxacin not to exceed 1 gram daily in children. w60-day duration is to prevent inhalational anthrax. Patient information sheets at www.bt.cdc.gov *Source MMWR 2001;50:909–19
  9. 9. Inhalational Anthrax Treatment Protocol*Category Initial therapy (intravenous) DurationChildren Ciprofloxacin Switch to oral 10–15 mg/kg Q 12 hrs therapy when OR clinically Doxycycline appropriate: >8 yrs and >45 kg: Ciprofloxacin 100 mg Q 12 hrs 10–15 mg/kg Q 12 hrs >8 yrs and <45 kg: OR 2.2 mg/kg Q 12 hrs Doxycycline <8 yrs: >8 yrs and >45 kg: 2.2 mg/kg Q 12 hrs 100 mg BID AND >8 yrs and <45 kg: One or two additional 2.2 mg/kg BID antimicrobials <8 yrs: 2.2 mg/kg BID**Ciprofloxacin not to exceed 1 gram daily wContinue for 60 days (IV and po combined) Patient information sheets at www.bt.cdc.gov *Source MMWR 2001;50:909–19
  10. 10. Immune Protection Against Anthrax Live cellular vaccines  "Sterne" type live spore  Former USSR STI live spore  "Pasteur" type Sterile, acellular vaccines  US "anthrax vaccine adsorbed" (AVA)—not licensed for use in civilian populations  UK "anthrax vaccine precipitated" (AVP)
  11. 11. Other Bacillus species: B. cereus, B. subtlis Large, motile, saprophytic bacillus with Heat resistant spores Lab diagnosis – Demonstation of large number of bacilli in food Food poisoning (meat, poultry, and soups)  Diarrheal syndrome (Heat labile enterotoxin)  Emetic form (Pre formed heat and acid stable toxin) ( with fried rice)Bacillus subtilis Common laboratory contaminant
  12. 12. Anaerobic Gram-positive spore forming bacilli: 1. Closteridium perfringens: Gas gangrene and Food Poisoning Gram-positive, anaerobic, nonmotile, capsulated, spore-forming rods  Clostridium (Greek Kloster meaning spindle)  Spores if formed are oval, sub-terminal and non bulging Causes Gasgangrene: How?  Saccharolytics strongly ferment carbohydroates and produce acid and gas  Proteolytic digests proteins, blackening soul smell due to sulfur compounds, in addition to toxins food poisoning: How? (enterotoxin heat labile toxin produced in colon, -toxin responsible for necrotizing enterocolitis) toxin  Lyses of RBCs, platelets, leucocytes and endothelial cells that increased vascular permeability leading to Hepatic toxicity and myocardial dysfunction
  13. 13. clostridium perfringenes infection Gas gangrene necrotizing enterocolitis: Food poisoning in chicken
  14. 14. Diagnostics: Litmus Milk Reaction showing Saccharolytic and proteolytic properties of Cl. perfringnes 1- Acidic Reaction Fermented to Litmus Indicator Lactose Acid Pink Color in Milk 2- Basic Reaction Digestion Litmus IndicatorCasein Alkaline amines Blue Colorin Milk 2- Stormy fermentation Too much acid and gas
  15. 15. Anaerobic Media Thioglycollate broth  Sodium thioglycollate (Reducing agent, obsorbs O2)  Rezazurin (redox indicator, can be added)  Soft-liquid Agar Robertsons Cooked Meat Medium Meat particles of heart muscles contain hematin & glutathione reducing agent Anaerobic JarPlastic jar with a tightly fitted lid. Hydrogen isintroduced from commercially available hydrogen generator envelop.10 ml of water is added to envelop immediately before placing it in the jar. Hydrogen and carbon dioxide will release and react with oxygen in the presence of catalyst to form water droplet
  16. 16. Treatment of illness No specific treatment. Supportive care include:  Restore intravenous fluid, monitor urine, and control fever and pain  Consider hyperbaric oxygen therapy. Why?  Clostridia lack superoxide dismutase, making them incapable of surviving in the oxygen-rich environment created within a hyperbaric chamber. This inhibits clostridial growth Antibiotics as high doses of penicillin, Clindamycin may help The hallmarks of this disease are rapid onset of myonecrosis with muscle swelling, severe pain, gas production, and sepsis, so controlling these is priority
  17. 17. Clostridium tetani: Tetanus (meaning Contract in Greek) Gram-positive, anaerobic, motile, drum-stick spore- forming rod commonly found: Soil, GI tracts of animals, environments. Therefore, spores enter through animal bites, accidental cuts, punctures, wounds, burns, umbilical stumps, frostbite, and crushed body parts. Common disease symptoms:  Tetanospasmin – Heat labile neurotoxin blocks release of neurotransmitter (glycine)for muscular contraction; muscles contract uncontrollably. Tetanolysin, heat stable hemolysin  Death most often due to paralysis of respiratory muscles  Estimated human lethal dose(2.5 ng/kg). Diagnosis is mostly by physical, medical, clinical symptoms and immunization history
  18. 18. Types of Tenaus Generalized Tetanus: spreads to muscles of the face, neck and truck in usually a descending pattern. local tetanus: toxin reaches motor nerve endings, neurones of the peripheral nerve to the anterior horn cells, and cause local tetanus Ascending tetanus: toxins spreads upwards Neonatal tetanus: …generalized baby spasm.Usually if the mother has not been immunized.Cephalic Tetanus: Rare; from otitis media
  19. 19. Diagnosis, Prophylaxis, and treatment options Diagnosis: Gram stain  Spore are diagnostic, bigger than bacteria, and bulge as drum-stick  Diagnosis is mostly by physical, medical, clinical symptoms and immunization history Prophylaxis, and treatment options  Antitoxin therapy with human tetanus immune globulin; inactivates circulating toxin  Control infection with penicillin or tetracycline; and muscle relaxants  Supportive therapy (ventilator)  Vaccine available; booster needed every 10 years  Part of regular vaccination schedule:  Triple Vaccine DPT (Diphtheria, Pertussis, Tetanus)  Nowadays: DTaP-Polio-Hib
  20. 20. Principles of vaccination“Immunological Memory”
  21. 21. Recent schedule for Vaccination of Newborns in Saudi Arabia. Starting January 2008. Age at visit Vaccines • BCG At birth • HepB • IPV 2 - Months • [ DTP, HepB , Hib ] • OPV 4 - Months • [ DTP, HepB, Hib ] • OPV, 6 - Months • [ DTP, HepB , Hib ] • Measles ( mono ) 9 - Months • OPV ,MMR 12 - Months • Varicella • OPV 18 - Months • DTP, Hib • Hepatitis (A) 24 - Months • Hepatitis (A) 4 - 6 Years • OPV,DTP,MMR, Varicella.
  22. 22. Clostridium Botulism : Case Presentation An afebrile and alert patient reported at a local hospital with blurred and double vision, muscle weakness, drooping eyelids, slurred speech, and apparent difficulty swallowing was. Immediate treatment was suggested including: Antitoxin administration Supportive Care  mechanical ventilation  body positioning  Induced vomiting
  23. 23. Clostridium botulism (Botulus = sausage in Latin) Gram positive, anaerobic, Mobile, subterminal spore forming bacilli Three botulism Types:  Foodborne botulism  (incubation period ) 6 hours-8 days ( Preformed toxin ingested from contaminated food) home canned Food, honey, crushed wounds, drug injection  Infant botulism, foods such as honey  Wound botulism (incubation period) > 4 days
  24. 24. Mechanism of Botulism toxin Produce seven botulism toxins A –G  One of the exteremely potent toxins known 1 aerosolized gram could potentially kill 1 million people  Prevents release of neurotransmitter acetylecholine Toxin enters blood stream and binds to cholinergic nerves blocks release of acetylcholine and prevents muscle contractions resulting in descending paralysis starting with cranial nerves to downward to respiratory obstruction Toxin destroyed by boiling, but spores need higher temp
  25. 25. Botulism Laboratory Procedures Microscopic/culture not reliable, toxin detection and assay Toxin neutralization in mouse  serum, stool, gastric aspirate, suspect foods Isolation of C. botulinum  in food/faeces, wound, tissue, or gastric  Strict anaerobe, extremely sensitive to oxygen Clinical signs Electromyography also diagnostic
  26. 26. Prophylaxis and Treatment Immediate Intensive care once suspected clinically…  Ventilator for respiratory failure  trivalent antitoxin, administer gastric lavage,  metronidazole or penicillin eliminates veg form from GI, Botulinum antitoxin  Derived from equine source  Trivalent and bivalent antitoxins available through the CDC  Licensed trivalent antitoxin neutralizes type A, B, and E and botulism toxins Botulism immune globulin  Infant cases of types A and G
  27. 27. Therapeutic uses of Botulism Toxin Involuntary muscles, such as uncontroled eye movements Cosmetic useCaution required: 70 yrs old underwentbotulinum toxin injectionto the left inferior rectus muscle,Resulted in loss of the muscle
  28. 28. Clostridium difficile-Associated Diarrhea (CDAD) A group of long term facility patients who were under extended antibiotic treatment all suddenly developed watery diarrhea 10 to 15 times a day, dehydration, fever, loss of appetite, nausea, and abdominal pain/tenderness, and signs of pseudomembranous colitis (damaged tissues,mucus in feces). Upon a quick Gram staining, gram positive spore forming bacilli dominated in samples from all patients. Reason: Antibiotic overuse  Long term treatment with broad-spectrum antibiotics kills the other bacteria, allowing C. difficile to overgrow, produce enterotoxins that damage intestines, cause diarrhea and colitis
  29. 29. Clostridium difficile Gram positive, anaerobic spore forming, bacilli Normal resident of colon In the industrialized world, it is one of the most common diarrheal infections in hospitals and long-term care facilities Causes antibiotic-associated colitis  relatively non-invasive; treatment with broad-spectrum antibiotics kills the other bacteria, allowing C. difficile to overgrow Produces enterotoxins that damage intestines Major cause of diarrhea in hospitals Increasingly more common in community acquired diarrhea
  30. 30. Treatment and prevention Mild uncomplicated cases respond to fluid and electrolyte replacement and withdrawal of antimicrobials. Severe infections treated with oral vancomycin or metronidazole and replacement cultures Increased precautions to prevent spread