4. Morphology
•
•
•
•
Gram positive bacilli in chains
Bacilli have characteristic squared ends
Bamboo stick appearance
Entire chain surrounded by polypeptide
capsule
• Spores donot stain by ordinary stain
• They are central – donot cause bulging
5.
6. Mc fadyean’s reaction
• Amorphous purplish material around
bacilli
• Represent capsular material
9. Growth charcteristics
• Aerobe
• On culture – raised, dull opaque, grayish
white colonies – frosted glass
appearance
• Edge of colony is composed of interlacing
chains of bacilli looking like matted hair –
medusa head appearance
• When grown with Penicillin added – the
cells become large, spherical and look like
string of pearls
14. Resistance
• Bacilli stay in bone marrow and skin
of dead animals for about a week
• Normal heat fixation may not kill
bacteria in blood smears
15.
16. • Spores are highly resistant to
chemical and physical agents
• Found in soil after 60 years
• Resistant to dry heat at 140 deg for
3 hours
• Resistant to boiling for 10 min
• They survive in 5% phenol for weeks
35. B. Cereus
• Cause of food poisoning
• Found in milk, cereals, spices, meat and
poultry
• Two types of food poisoning
– Acute – chinese fried rice – vomitting in 1-5
hrs after meal
– Chronic – After 8 hrs of ingestion
• Illnesses are mild – require no treatment
38. Gas gangrene
• Caused by Cl perfringens type A
• It is a rapidy spreading necrosis of
muscles
• Usually seen after extensive muscle
damage (contaminated) secondary
to trauma – road accidents, battle
field injury
41. Lab diagnosis
• Sample – muscle fragments or
necrotic debris
• Plated on appropriate culture media
42. Tetanus
• Characterised by tonic muscular
spasms, commencing at site and
slowly becoming generalised
• Disease follows injury too trivial to
be noticed
• Due to tetanospasmin toxin produced
by Cl tetani
52. types
• Food borne botulism
– eating food with pre formed toxin
– After 12 hrs of taking food
– Vomitting, constipation, difficulty in swallowing,
speaking, breathing
– Respiratory failure
• Wound botulism
– No gi manifestations
• Infant botulism
– Infants below 6 months
– Honey is an agent
– Poor feeding, pooling of oral secretions, loss of head
control
59. • Very resistant to common antiseptics
and disinfectants like dettol
• Susceptible to glutaraldehyde and
phenols
60. • Most common infection – otitis media
• In hospitals – wound infection, bed
sores, UTI following catheterisation
• Seen in equipments such as
respirators, endoscopes, bed pans,
lotions, eye drops