Post on 07-May-2015
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Spore forming bacteriaSpore forming bacteria
Dr. Dr. AshishAshish JawarkarJawarkar M.D.M.D.
TypesTypes• Aerobic – Bacillus• Anaerobic – clostridia
Bacillus – two major speciesB. Anthracis – causes AnthraxB. Cereus – food poisoning
B. B. AnthracisAnthracis• Morphology• Growth characteristics• Biochemical reactions• Resistance• Pathogenicity and virulence• Epidemiology• Diseases caused• Laboratory diagnosis• Treatment
MorphologyMorphology• 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
Mc Mc fadyeanfadyean’’ss reactionreaction• Amorphous purplish material around
bacilli• Represent capsular material
• Morphology• Growth characteristics• Biochemical reactions• Resistance• Pathogenicity and virulence• Epidemiology• Diseases caused• Laboratory diagnosis• Treatment
Growth Growth charcteristicscharcteristics• 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
Frosted glassFrosted glass
Medusa headMedusa head
String of pearlsString of pearls
• Morphology• Growth characteristics• Biochemical reactions• Resistance• Pathogenicity and virulence• Epidemiology• Diseases caused• Laboratory diagnosis• Treatment
ResistanceResistance• Bacilli stay in bone marrow and skin
of dead animals for about a week• Normal heat fixation may not kill
bacteria in blood smears
• 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
• Morphology• Growth characteristics• Biochemical reactions• Resistance• Pathogenicity and virulence• Epidemiology• Diseases caused• Laboratory diagnosis• Treatment
PathogenicityPathogenicity and virulenceand virulence• Capsule – helps to escape
phagocytosis• Toxin – leads to anthrax
• Morphology• Growth characteristics• Biochemical reactions• Resistance• Pathogenicity and virulence• Epidemiology• Diseases caused• Laboratory diagnosis• Treatment
EpidemiologyEpidemiology• Seen in animal handlers – those who
carry skin/hides on back • Hide porter disease
• Morphology• Growth characteristics• Biochemical reactions• Resistance• Pathogenicity and virulence• Epidemiology• Diseases caused• Laboratory diagnosis• Treatment
AnthraxAnthrax• Agent for bioterrorism
• Active outbreak in India – in sheep –near Tamilnadu-Andhrapradeshborder
• Causes cutaneous infections and meningitis
AnthraxAnthrax• Usually an occupational disease –
contact with infected animals• Types – cutaneous, pulmonary,
intestinal
CutaneousCutaneous anthraxanthrax
• Lesion called malignant pustule• Central area is black due to necrosis
– eschar• Resolves spontaneously
Pulmonary anthraxPulmonary anthrax• Hemmorhagic pneumonia• Hemmorhagic meningitis• Seen in people engaged in sorting
wool – wool sorters disease
Intestinal anthraxIntestinal anthrax• Seen in communities that eat dead
animals • Bloody diarrhoea
• Morphology• Growth characteristics• Biochemical reactions• Resistance• Pathogenicity and virulence• Epidemiology• Diseases caused• Laboratory diagnosis• Treatment
Lab diagnosisLab diagnosis• Sample
– Skin – biopsy/materia– Sputum– Stool
• Gram stain• Culture• Special test – direct fluoroscent antibody
test• PCR
• Morphology• Growth characteristics• Biochemical reactions• Resistance• Pathogenicity and virulence• Epidemiology• Diseases caused• Laboratory diagnosis• Treatment
B. CereusB. 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
ClostridiaClostridia• Gram positive, spore forming• Anaerobic
–Cl perfringens – gas gangrene–Cl tetani – tetanus–Cl botulinum – food poisoning–Cl difficile – acute colitis
• Clostridia – kloster - spindle
Gas gangreneGas 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
Clinical featuresClinical features• Increasing pain, edema and
tenderness of the affected limb• Accumulation of gas
Lab diagnosisLab diagnosis• Sample – muscle fragments or
necrotic debris• Plated on appropriate culture media
TetanusTetanus• 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
Different forms of tetanusDifferent forms of tetanus• Generalized tetanus
Local tetanusLocal tetanus
Cephalic tetanusCephalic tetanus• After a head injury or local infection• Trismus – lock jaw
Neonatal tetanusNeonatal tetanus• Infection follows unhygeinic practices
after delivery• Applying cowdung on umbilical
stump
• Diagnosis is clinical – by the time symptoms appear, organism is no longer present in lesion
TreatmentTreatment• Human tetanus immunoglobulin –
can neutralize toxin
PreventionPrevention• DPT vaccine
ClCl botulinumbotulinum• Produces neurotoxin• Causes paralysis• Used in treating wrinkles
typestypes• 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
ClCl difficiledifficile• Antibiotic associated diarrhoea
(clindamycin)• Disrupts normal flora• Psuedo membranous colitis
PseudomembranousPseudomembranous colitiscolitis
PseudomonasPseudomonas
P. P. aeruginosaaeruginosa• Pseudo – false• Monas – mono – single unit• Slender gram negative bacillus with
polar flagellum
• Produces bluish green pigment –pyocyanin on culture
• Very resistant to common antiseptics and disinfectants like dettol
• Susceptible to glutaraldehyde and phenols
• 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