Flashcards in Lecture 8 Deck (52):
Define Cl Tetani
a soil dwelling saprophytic organism- spores wide spread in soil- slender thin rods with tennis racket appearance
Portal of entry for Cl tetani
skin-through wound-like nail prick, road accidents where there is contamination of mud, skin popping in drug addicts
WHat does Cl tetani cause?
Tetanus- lock jaw
Can Cl tetani cause infection in newborns?
can occur through umbilical cord cutting, through circumcision in developing countries-- spores germinate at the wound
What do vegetative cells of Cl Tetani produce?
exotoxin which spreads through nerve fibers to spinal cord
What does exotoxin block release of?
glycine- inhibitory neurotransmitter- in spinal synapse causing muscle spasms (tetany)
Is vaccine effective for Cl Tetani?
YES- because only one Ag variety (sero type)
How is Tetanus defined?
characterized by spasm of skeletal muscles starting from face, hardening of facial muscles results in grim face
What is the hardening of facial muscles in Cl Tetani known as
What is spasm of muscles of mastification from Cl Tetani lead to?
Lock Jaw known as trismus
What does spasming of back muscles result in?
Arching of back known as Opisthotonus
What type of poisoning resembles the condition of Cl Tetanis
How do you treat tetanus?
Tetanus antitoxin serum to neutralize unbound toxins, penicillin and metronidazole may be useful- maintain adequate airway, muscle relaxants like valium
How do you prevent tetanus?
toxoid vaccine (DTaP) is available
What is the natural habitat of Cl Botulinum?
soil- spores are found in soil, found in contaminated vegetables, alkaline vegetables, spores germinate in anaerobic conditions
What is an indication that bacteria may be growing in canned vegetables?
swollen/bloated can tins
How do you get the Cl Botulinum toxins?
ingested- absorbed from gut and carried to neuromuscular junction
What does Cl Botulinum cause in a person and how?
flaccid paralysis- blocks release of acetylcholine- can cause paralysis of ocular muscles causing vision problems- respiratory failure when pharyngeal muscles are relaxed
Will Cl Botulinum present with a fever?
Can an infant get Cl Botulinum?
yes- contaminated honey- spores germinate in gut and cause silent death of an infant
Treatment for Cl Botulinum?
Trivalent antitoxin available- antitoxin made from horses and given with respiratory support
Prevention of Cl Botulinum
The tosin is relatively heat labile so boiling vegetables/food will inactivate toxins
What are some medical uses of Cl Botulinum?
to remove wrinkles on forehead or to relieve spastic torticollis (wry neck)
Describe Cl Perfringens
Gram + rod shaped, anaerobic spore forming bacterium
What 2 diseases can Cl Perfringens cause?
Gas gangrene and food poisoning
Describe gas gangrene
vegetable forms are members of normal flora of colon and vagina- spores are found in soil
Most common mode of contamination of Gas gangrene
wound contamination with soil/mud (war wounds, automobile accidents, septic abortion
How is the gas gangrene produced?
organism grows in traumatized tissues, produced alpha toxin which causes necrosis of muscle and RB cells and enzyme degradation produces gas in tissues
Results of Gas gangrene
pain, edema and cellulitis, crepitations, massive hemolysis, jaundice, renal failure, shock and death - high mortality rate
Treatment for gas gangrene
Penicillin G- wound should be derided- surgical amputation if necessary
How is Cl perfringens seen in colonies on agar plates?
culture grown in anaerobic conditions and produces double zone of hemolysis
Explain food poisoning from Cl perfringens
spores contaminated food- heat resistant and grow in large numbers in reheated meat dishes
Explain mode of food poisoning from Cl perfringens
After ingestion, sporulation occurs in gut and enterotoxin is liberated causing diarrhea
Treatment of food poisoning
symptomatic- ends with time
What is the most common nosocomial infection?
What does Cl difficile cause?
antibiotic associated pseudo membranous colitis
How is Cl difficile transmitted?
by fecal-oral route
Explain mode of infection of Cl difficile
antibiotics suppress normal flora allowing organism to over grow
Clinical manifestations of Cl difficile
it causes non bloody diarrhea, yellow white plaques in the colon visible by sigmoidoscopy
Treatment of Cl difficile
causative agent should be stopped, metronidazole and fluid replacement
Define toxic megacolon
paralysis of one segment of the colon- rare complication which may need surgical resection
Describe Corneybacterium Diptheriae
bacteria is club shaped, arranged in V or L forms, beaded appearance with granules- non motile (Chinese letter formation)
What is the source for Diptheriae?
humans are the only source
How is Diptheriae transmitted?
air born droplets
How does Diptheriae cause damage?
the organism produces an exotoxin, which causes damage to eukaryotic cell- any tissue can be affected
What disease does Corneybact. diphtheria cause?
Diptheria- local inflammation with fibrinous exudates that form tough, adherent, greyish white psuedomembrane over throat and tonsils, fever, sore throat, bulls neck
3 major complications caused by Diptheria
1. extension of membrane in larynx and trachea causing airway obstruction 2. myocarditis with arrhythmias and circulatory collapse 3. nerve paralysis (especially cranial)
Treatment for Diptheria
administration of antitoxin to neutralize unbound toxins, penicillin G and erythromycin, tracheostomy may be necessary , DPT vaccine
Define lysteria monocytogens
causes sepsis and meningitis in new borns as well as immunosupressed individuals (renal transplant)- present on animals, plants, soil, mainly food born infection
What does lysteria monocytogens cause?
abortion/premature delivery in pregnant women/flu/watery diarrhea symptoms
Can lysteria monocytogens affect babies?
YES- crosses over placenta and produces neonatal sepsis