UII Gram Pos Spore-Form

7/27/2019 UII Gram Pos Spore-Form

1/30

Spore FormingGram-positive Bacilli

Titik Nuryastuti

Microbiology Department,Fac. of Medicine, UGM


2/30

SporesWhy do bacteria produce spores?

Survival

Classification

Definition = a resting cell, highlyresistant to dessication, heat, and

chemical agents; when returned tofavourable conditions bacteria re-activated, the spores germinate toproduce single vegetative cells.


3/30

SF Bacteria- Bacillus Aerobic, G+ rods in chains, spores are

located in center of the non-motile bacilli

Found in soil, water, air and vegetation Spores are viable for decades.

B. cereus produce enterotoxin and cause

food poisoning. B. anthracis infection in human through

injured skin (cutaneous anthrax), mucousmembranes (GI anthrax), or inhalation of

spores into lung.


4/30

Bacillus anthracis


5/30

Spores germinate in the tissue of entry,and growth of vegetative organisms

result in formation of a gelatinousoedema and congestion.

Spread via lymphatics to bloodstream

and multiply freely in blood and tissues. Capsulated, poly-D-glutamic acid

capsule is antiphagocytic

SF Bacteria- Bacillus


6/30

Anthrax toxin is made up of three proteins: Protective antigen (PA), edema factor (EF) and lethal

factor (LF).

Clinical finding : Cutaneous Anthrax(malignant pustule):

Generally occurs on exposed surfaces of the arms,face and neck through wound contamination by thespores of the organism. About 95% of the cases with

amortality rate 20% . Inhalation Anthrax(wool sorter disease):

About 5% of the cases with 85-90% mortality. Treatment: ciprofloxacin, penicillin G along with

gentamicin and streptomycin.

SF Bacteria- Bacillus


7/30

SF Bacteria-Bacillus Lab diagnosis :

Gram staining

Culture on Blood agar Speciment :

Fluid, pus, blood, sputum


8/30

SF Bacteria - ClostridiumAnaerobic, G+, motile rods

Their natural habitat is the soil or the

intestinal tract of human and animals,where they live as saprophytes

Found in soil, animal faeces.

Spores is placed centrally, subterminallyor terminally; most species are motilewith flagella.


9/30

SF Bacteria - Clostridium Many decompose proteins of form

toxins, some do both

Among the pathogens are theorganisms causing botulism, tetanus,gas gangrene, and pseudomembranouscolitis.

C. botulism, C. tetani, C. perfringens, C.difficile


10/30

SF Bacteria - Clostridium Many form colonies with a zone of

haemolysis on blood agar. C perfringens

typically produce multiple zones ofhaemolysis around colonies.


11/30

Identification

In most species, the spores are locatedcentrally, subterminally or terminally.

Most species of Clostridia are motilewith peritrichous flagella


12/30

Clostridium

Epidemiology Ubiquitous

Present in soil, water, sewage

Normal flora in GI tracts of animals andhumans

Pathogenesis Spore formation

resistant to heat, dessication, and disinfectants can survive for years in adverse environments Rapid growth in oxygen deprived, nutritionally

enriched environment Toxin elaboration (histolytic toxins, enterotoxins,

neurotoxins)


13/30

Clostridium botulinum

Epidemiology

Commonly isolated in soil and water

Human disease associated with botulinum toxin A, B,

E, F Pathogenesis

Blocks neurotransmission at peripheral cholinergic

synapses

Prevents release of acetylcholine, resulting in musclerelaxation

Recovery depends upon regeneration of nerve

endings


14/30

SF Bacteria C.botulinum C botulinum causes botulism

-Distinguished by antigenic type of toxin

Spores are resistant to 100C for many hours,diminished at acid pH or high salt.

Toxin - 7 antigenic varieties (AG). A, B, E(F) mainly harmful to human.

Botulinum toxin is absorbed from gut andbinds to receptors of presynaptic nervoussystem and cranial nerves.

Lethal dose to human 1-2 g.


15/30

SF Bacteria - ClostridiumPathogenesis

Most cases, through ingestion of uncooked

food. Toxin acts by blocking release of acetylcholine

at synapses and neuromuscular junctions flacid paralysis.

Symptoms such as visual disturbances,inability to swallow, speech problem; seldomwith no apparent GI symptoms; no fever.


16/30

Botulism

Clinical SyndromesFoodborne botulism

Associated with consumption of preformed toxin Home-canned foods (toxin A, B)

Preserved fish (toxin E) Onset of symptoms 1-2 days Blurred vision vision, dilated pupils, dry mouth, constipation Bilateral descending weakness of peripheral muscles; death

related torespiratory failure

Infant botulism Consumption of foods contaminated with botulinum spores 6-10% of syrups or honeys Disease associated with neurotoxin produced in vivo Onset of symptoms in 3-10 days

Wound botulism (skin popping)

Asymptomatic adult carriage


17/30

Botulism: Treatment

Treatment

Supportive care

Elimination of organism from GI tract Gastric lavage

Metronidazole or penicillin

Botulinum Immunoglobulin (BIG): pooled plasma from adults

immunized with pentavalent (ABCDE) botulinum toxoid

Trivalent equine Immunoglobulin (ABE)

Prevention

Prevention of spore germination (Storage


18/30

SF Bacteria - Clostridium

floppy baby = infant botulism. C botulinumspores in babies food.

Treatment antitoxins raised in horses.

Trivalent (A, B, E) antitoxin must be promptlyadministered intravenously with precautions;

plus adequate ventilations.


19/30

Clostridium tetani

Epidemiology Spores found in most soils, GI tracts of animals Disease in un-vaccinated or inadequately immunized Disease does not induce immunity

Pathogenesis Spore inoculated into woundTetanospasmin

Heat-labile neurotoxin Retrograde axonal transport to CNS Blocks release of inhibitory neurotransmitters (eg. GABA) into

synapses, allowing excitatory synapses to be unregulated. Thisresults in muscle spasms Binding is irreversible

Tetanolysin Oxygen labile hemolysin, unclear clinical significance


20/30

SF Bacteria C.tetani

Clostridium tetani cause tetanus.

Distinguishable by specific flagellar antigens.

Pathogenesis: Wound contamination, notan invasive organism. The toxins releasedfrom vegetative cells reaches the CNS and

rapidly becomes fixed to receptors in thespinal cord and brain stem and exerts theiraction.


21/30

C. tetani

Toxins: Tetanospasmin

binds to receptors on the presynaptic

membranes of motor neurons.

Clinical Findings: Incubation period:

4-5 days to many weeks. The diseaseis chacterized by tonic contraction ofvoluntary muscles.


22/30

Tetanus

Treatment

Debridement of wound

Metronidazole

Tetanus immunoglobulin

Prevention Vaccination with a series of 3 tetanustoxoid

Booster dose every 10 years


23/30


24/30

C. perfringens

Many different- toxin producing clostridia canproduce invasive infections(including myonecrosisand gas gangrene) if introduced into damaged tissue.About 30 species of clostridia may produce such aninfection, but the most common in invasive disease isC. perfringens(90%). An enterotoxin ofC.perfringensis a common cause of food poisoning.

Toxins: produce different types of toxins andenzymes that result in spreading infection. They

have lethal, necrotizing, and hemolytic properties. Pathogenesis: Wound contamination. Clinical Findings: Infection spreads in 1-3 days.

Crepitation in subcutaneous tissue and muscle, fever,tissue necrosis, hemolytic anemia, severe toxemia

and death.


25/30

Clostridial soft tissue infections

Crepitant cellulitis

Fascitis

Myonecrosis


26/30

Clostridial myonecrosis

Clinical course

Symptoms begin 1-4 days after inoculation and

progresses rapidly to extensive muscle necrosis andshock

Local area with marked pain, swelling, serosanguinousdischarge, bullae, slight crepitance

May be associated with increased CPK

Treatment Surgical debridement

Antibiotics

Hyperbaric oxygen


27/30


28/30

Clostridium difficile

Epidemiology Endogenous infection

Colonizes GI tract in 5% healthy individuals Antibiotic exposure associated with overgrowth ofC. difficile

Cephalosporins, clindamycin, ampicllin/amoxicillin Other contributing factors: agents altering GI motility,surgery, age, underlying illness

Exogenous infection Spores detected in hospital rooms of infected patients

PathogenesisEnterotoxin (toxin A)

produces chemotaxis, induces cytokine production andhypersecretion of fluid, development of hemorrhagic

necrosisCytotoxin (toxin B)

Induces polymerization of actin with loss of cellularcytoskeleton

d ff l l


29/30

C.difficilecolitis

Clinical syndromes Asymptomatic colonization Antibiotic-associated diarrhea Pseudomembranous colitis

Diagnosis Isolation of toxin Culture

Treatment Discontinue antibiotics

Metronidazole or oral vancomycin Pooled human IVIG for severe disease Probiotics (saccharomyces boulardii) New drugs (nitazoxanide, tolevamer) Relapse in 20-30% (spores are resistant)


30/30

The Genus

ClostridiumLeft. Stained pus from amixed anaerobicinfection. At least three different clostridiaare apparent. Right. Electron micrograph of

Clostridium tetani

C botul inum

C.perfringens

C tetani

C. dif fi cile

Documents

UII Gram Pos Spore-Form