Post on 10-May-2015
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بسم الله الرحمن الرحيمبسم الله الرحمن الرحيم
FAMILY: BACILLIACEAEFAMILY: BACILLIACEAEProf. Khalifa Sifaw GhengheshProf. Khalifa Sifaw Ghenghesh
1. GENUS: 1. GENUS: BACILLUSBACILLUS
• Gram +ve bacilli
• Aerobic
• Spore-Forming
i. i. Bacillus anthracisBacillus anthracis• >> Anthrax.
• Large, Square - ended Rods, Arranged in Chains.
• Non-Motile.• Spores:• Capsule: – Purple Stained >> McFadyan's Method
(Polychrome Methylene Blue).
• Colonies on BA: "Medusa Head Appearance"
Bacillus anthracisBacillus anthracis
An electron micrograph of spores from An electron micrograph of spores from the Sterne strain ofthe Sterne strain of Bacillus anthracisBacillus anthracis
Bacillus anthracisBacillus anthracis McFaydean capsule McFaydean capsule stain, grown at 35stain, grown at 35ooC, in defibrinated C, in defibrinated
horse blood.horse blood.
DISEASE:• In Animals: >> Septicaemia.
• In Humans: i. Cutaneous Anthrax > Malignant pustule
ii. Pulmonary Anthrax (Wool-Sorter'sDisease).
iii. Gastrointestinal Anthrax.
Cutaneous AnthraxCutaneous Anthrax
Anthrax lesion on the skin of the Anthrax lesion on the skin of the forearm caused by forearm caused by Bacillus anthracisBacillus anthracis
PATHOGENESIS• Capsule > Invasiveness– D-glutamic acid
• Exotoxin (Plasmid mediated)i. Protective Factor (Antigen).
ii. Oedema Factor.
iii. Lethal Factor.
Blocks the Adenyl Cyclase Pathway > Increases vascular Permeability > Shock
LABORATORY DIAGNOSIS:• Specimens obtained from:
a malignant pustule, sputum, blood.
- Gram stain + fluorescent-antibody stain.
- Motility
- Capsule formation: Sodium bicarbonate +CO2
- String-of-pearls reaction:
- Mouse test:
- API
>> Demonstration of Abs to the organism:
Bicarbonate agar and blood agar Bicarbonate agar and blood agar plate cultures of plate cultures of Bacillus anthracisBacillus anthracis
Negative encapsulation: Blood agar and Negative encapsulation: Blood agar and bicarbonate agar plate cultures of bicarbonate agar plate cultures of
Bacillus cereusBacillus cereus
• TREATMENT– Penicillin, Ciprofloxacin
• IMMUNIZATION–Animals > Live spore vaccine
(Sterne strain)
–Workers at Risk of Exposure >
Anthrax Vaccine Absorbed (AVA) >> “Alum precipitated toxoid”
ii. ii. Bacillus cereusBacillus cereus
• Food Poisoning.
• Clinical Syndromes:
i. Severe Nausea &Vomiting.
ii. Abdominal Cramps & Diarrhoea.
PATHOGENICITY:>> Due to an Enterotoxin.
• Also Causes Disease in Patients with Underlying Disease.
• TREATMENT:
>> Tetracycline, Erythromycin.
• iii. B. subtilis:
• iv. B. stearothermophilus.
2. GENUS: 2. GENUS: CLOSTRIDIUMCLOSTRIDIUM
• Gram +ve bacilli
• Anaerobic,
• Spore Forming
- Spores:
Ink Stain of Sporulating Ink Stain of Sporulating ClostridiumClostridium--spores appear clear, vegetative cells darkspores appear clear, vegetative cells dark
i.i. Clostridium perfringens Clostridium perfringens
• Nonmotile
• Spores Not Produced in Ordinary Media.
• Aerotolerant Anaerobe.
• 5 Types: A - E
Gram stain of Gram stain of Clostridium perfringensClostridium perfringens
Exudate smear of Exudate smear of Clostridium perfringensClostridium perfringens
Tissue smear of Tissue smear of Clostridium perfringensClostridium perfringens
DISEASE:
• Clostridial Myonecrosis.
• Less Severe Wound Infections.
• Food Poisoning.
Patient with gas gangrenePatient with gas gangrene
LABORATORY IDENTIFICATION
• In Chopped Meat - Glucose Medium:
• On BA:
• On Egg Yolk Agar: >> Precipitation (Opalescence).
• Milk Media: Stormy Formation.
• Nagler Reacrion:
Blood agar plate with Blood agar plate with Cl. perfringensCl. perfringens characteristic double zone of hemolysischaracteristic double zone of hemolysis
PATHOGENICITY & CLINICAL INFECTION-Toxin: Acts on Lecithin-Containing Lipo-
protein Complexes in the Cell Membrane.
• Predisposing Factors:i. Trauma with Deep and Lacerated or Crush
Wounds of Muscle Etc.
ii. Require a Reduced Oxygen Tension and
Reduced Oxidation Reduction Potential
for Growth.
FOOD POISONING:
• Cl. perfringens Type A >> Enterotoxin.
> Acute Abdominal Pain and Diarrhoea.
LABORATORY DIAGNOSIS:• Important: Diagnosis of Clostridium
Myonecrosis Should Be Rapid and Made on Clinical Grounds.
i. Direct Smear and Gram Stain of Material
from Deep Within the Wound.
ii. Culture: Tissue Aspirates or Deep Swabs Taken from Affected Muscle.
TREATMENT:• Clostridium Myonecrosis:
i. Surgical Removal of All Infected and
Necrotic Tissue.
ii. Antibiotic and Antitoxin Therapy.
iii. Adminstration of Hyperbaric Oxygen.
• Food Poisoning:
Clostridia That May Be Associated
with Gas Gangrene:
• Cl. perfringens Type A• Cl. septicum• Cl. novyi Type A• Cl. histolyticum• Cl. Sordellii
Human case of malignant edema Human case of malignant edema caused by caused by Cl. septicumCl. septicum
ii. ii. Clostridium tetaniClostridium tetani
• > Tetanus.
• > Terminal Spores with Drumstick
Appearance.
• > Obligate Anaerobe.
Clostridium tetaniClostridium tetani Gram Positive RodsGram Positive Rods
Clostridium tetaniClostridium tetani
VIRULENCE FACTORS:• Tetanus Toxin (Tetanospasmin) >
Neurotoxin.
i. An Intercellular Toxin Released by
Cellular Autolysis.
ii. Inhibits the Release of Inhibitory
Transmitters.
iii. Toxoid.
CLINICAL INFECTION & PATHOGENESIS• "Tetanus is Generalized in Nature".
i. Unimmunized Rural Population.
ii. In Practice: Simple Puncture Wounds >
Nail, Splinter or Thorn.
iii. In Traumatic Wounds > Compound
Fractures, Dental Extractions, Etc.
iv. Tetanus Neonatrum:
v. Postoperative Tetanus:
Drawing of a Soldier dying of Drawing of a Soldier dying of Tetanus (Opisthotonos)Tetanus (Opisthotonos)
A patient presented with facial tetany. A patient presented with facial tetany. Note the contraction of the masseter and Note the contraction of the masseter and
neck musclesneck muscles
LABORATORY DIAGNOSIS:• > Diagnosis on Clinical Grounds.
TREATMENT:• i. Antitoxin.• ii. Debridement of Wound and Removal of • any Foreign Bodies.• iii. Pencillin >>> In Large Doses.• iv. Mild Tetanospasm: >>> Barbiturates.• v. Severe Cases: • >>> Use Curare - Like Agents.• >>> Tracheostomy.• >>> Careful Control of the
Environment.
PREVENTION:> Prompt and Adequate Cleaning of
Wounds.
i. Active Immunity.
ii. Passive Immunity.
iii. iii. Clostridium botulinumClostridium botulinum
• > Botulism.
• > Gram +ve, Spore Forming Bacilli.
• > Strict Anaerobe.
Gram Stain of Gram Stain of Cl. botulinumCl. botulinum, , Characteristic Long RodsCharacteristic Long Rods
A photomicrograph of A photomicrograph of Clostridium botulinumClostridium botulinum type A type A
Blood Agar Plate with Blood Agar Plate with C. botulinumC. botulinum
VIRULENCE FACTORS• Botulinum Toxin >>> Neurotoxin.–Serologically 8 Toxins >>
A, B, C1, C2, D, E, F & G.
> Affect the Cholinergic System > Blocks the Release of Acetylcholine (at Points in Peripheral Nervous System).
DISEASE IN HUMANS1. Food - Borne Botulism:> Incubation Period: 12-36 Hours to 8 days.
2. Infant Botulism:
LABORATORY DIAGNOSISi. Diagnosis Made Clinically.ii. Detection of Organism or Its Toxin in the Suspected Foodiii. Samples of Stool or Vomit
TREATMENT & PREVENTIONImportant: Specific Treatment Should
Begin as Quick as Possible.
>Polyvalent Antitoxin >>> Immediately.
>Physiological Support >>> ICU.
>NEVER Use a Swollen or Defective Can.
iv. iv. Clostridium difficileClostridium difficile
• Antibiotic Associated Colitis.
• Produce Two Major Protein Toxins
(A &B).
• Risk Factors: –Antibiotic Exposure.
–Old Age.
Clostridium difficileClostridium difficile
Scanning electron micrograph of Scanning electron micrograph of Clostridium difficleClostridium difficle
Intestinal Smear- Close Association Intestinal Smear- Close Association of of Cl. difficileCl. difficile with Neutrophils with Neutrophils
• Infection Can Be: –Endogenous or Exogenous.
• Nosocomial Spread: Due to Spores.
LAB DIAGNOSIS:1. Demonstration of Cytotoxin in Stool.
2. Isolation of the Microorganism.
TREATMENT:–Discontinuing Treatment.
–Vancomycin.