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100 Cards in this Set
- Front
- Back
human bite wounds
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oral flora
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animal bite wounds
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oral flora
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infected burn wounds
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nosocomial species and skin flora
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soil contaminated wounds
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anaerobic spore formers (and fungi)
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surgical site infections
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normal flora variable by site of wound and healthcare staff hygiene practices
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Human bites
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S. aureus and other normal oral flora
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animal bites
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pasteurella multocida and other anaerobes
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What are the most common isolate from human bites?
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viridans streptococci
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Pasteurella characteristics
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aerobic, gram (-), bipolar, non-motile
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Are pasteurella penicillin sensitive?
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Yes
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Is pasteurella slow lr rapidly progressive?
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rapidly progressive
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Virulence factors for Pasteurella
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LPS, capsule, cytotoxin and iron acquisition proteins
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Agar growth and pasteurella
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Grows well on blood and chocolate, but poorly on MAcConkey
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What is the distinctive smell of pasteurella due to?
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indole production
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Pasteurella - Catalase and oxidase (positive/negative)?
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Positive
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Zone of coagulation
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nearest the heat source, includes dead tissue forming the burn eschar
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zone of stasis
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area adjacent to the necrotic tissue in the coagulation zone is viable but risk of ischemia because of perfusion defects
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zone of hperemia
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the third area, which consists of relatively normal skin with increased blood flow and vasodilation and minimal cellular injury
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Most common burn wound infection isolates: gram positive
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s. pyogenes (most common in the past), Staph aureus (currently most common)
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Most common burn wound infection isolates: gram negative
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Pseudomonas aeruginosa, klebsiella pneumoniae, acinetobacter baumannii
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Most common burn wound infection isolates: fungi
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aspergillus and Candida
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Aspergillus is associated with _______
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increased mortality
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What are the two most common phyla of bacteria found on the skin?
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actinobacteria and firmicutes (gram +) cocci or rods.
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Firmicutes and G + C ration
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Low G + C ration
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How are firmicutes and actinobacteria differentiated?
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low G+C= firmicutes
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firmicutes most commonly found on skin
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staph, strep, clostridium
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actinobacteria most commonly found on skin
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coryne bacteria, propionibacteria
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2 most common surgical site infections
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s. aureus (30%), coagulase (-) staph (14%)
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The most common isolates of surgical site infections are members of the ______
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skin and GI tract microbiota
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Staph epidermidis: gram stain
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+
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Staph epidermidis: motility
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non-motile
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Staph epidermidis: coagulase activity
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negative
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Staph epidermidis: hemolycity
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gamma (non hemolytic)
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Staph epidermidis: aerobicity/
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faculatative anaerobe
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Staph epidermidis: salt and temp tolerance
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both
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Stap epidermidis commonly causes infections of:
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prosthetic heart valves, catheters and shunts, prosthetic joints
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How are staph and strep differentiated?
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catalase test - staph = (+). Strep = (-)
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Does staph love it some salt?
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Yes
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Staph aureus: gram stain
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+
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Staph aureus: catalase
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+
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Staph aureus: aerobicity
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facultative anaerobe
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Staph aureus: hemolycity
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B-hemolytic
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Staph aureus: salt and temp toleranct?
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both
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Staph aureus: color?
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golden (aureus)
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Staph aureus: polysaccharide capsule key characteristic?
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anti-phagocytic
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Staph aureus: coagulase?
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+
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How are S. Aureus and S. epidermidis differentiated?
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coagulase test (aureus is +)
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B-hemolytic staph sensitivity to bacitracin?
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resistant
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beta-hemolytic group A strep sensitivity to bacitracin?
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sensitive
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diseases od s aureus
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scalded skin syndrome, folliculitis, furuncles (boils), carbuncles, wound infection
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burns-
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sterile for about 48 hours, then colonized with skin microbiota. After 5 to 7 days the wound becomes colonized with yeast and or gram + and gram - bacteria from environment
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furuncles
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extension of folliculitis- large painful raised nodules
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carbuncles
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occur when furuncles coalesce
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Protein A
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binds to Fc portion of circulatin antibodies having an anti opsinization effect. I makes S. auerus a "stealth" bacteria
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Collagen binding protein
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c n a
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fibronectin bindind proteins
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fnbA
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sialoprotein adhesin
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staph cytolytic toxins
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alpha, Beta, sigma, gamma, P-V leukocidin
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staph exfoliative toxins
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A and B
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staph enterotoxins
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A throuh E, G, H, I
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staph toxic shock toxin
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TSST-1 (toxic shock syndrome toxin
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Super antigens of staph
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exfoliative Toxin A, enterotoxins, TSST-1
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Super antigens (Sag) bind what?
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TCR and MHC2 simultaneously
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The cytolytic toxins:
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lyse cell membranes
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exfoliative toxins site of action
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break down desmosomes that hold cells together in the epidermis
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desmoglein
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one of the proteins that hold cells together that exfoliatve toxin targets
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hyaluronidase
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hyrdolses extracellular matrix
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staphylokinase
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dissolves clots
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lipase
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allows for survival in subaceuous areas of the body
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Dnase
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hyrdrolyzes abcess material reducing viscosity so that the bacterial cell does not get traped and eliminated
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coagulase
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clumps staph cells and converts fibrinogen to fibrin to cause formation of a fibrin layer around the cells to protect them from phagocytosis
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Clostridium genus: where found?
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soil, water, sewage and normal microbial flora of GI tract
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Clostridium genus: spore formers?
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Yes
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Clostridium genus: aerobicity?
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obligate anaerobe
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Clostridium genus: normally found with what organisms in infection?
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faculatative anaerobes or aerobic
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Clostridium genus: what they produce
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exotoxins, enterotoxins and neurotoxins
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C. perfingens: shape and gram staining, aerobicity
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large rectangular, gram + anaerobic rods
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C perfingens: can spores be present?
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Yes, but rarely
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C. perfingens: alpha toxin
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lyses erythrocytes, platelets and leukocytes
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C. perfingens: Beta toxin
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intestinal stasis progressing to necrotizing enteritis
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C. perfingens: Epsilon toxin
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increaes the vascular permeability of GI
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C. perfingens: Iota toxin
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necrotic activity and increases vascular permeability
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soft tissue diseases associated with C. perfringens
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cellulitis, fasciitis or suppurative myositis, myonecrosis or gas gangrene
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Diagnostic tests for C. perfringens: does it grow in solid media in 10% CO2 in air?
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NO
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Diagnostic tests for C. perfringens: B-hemolysis characteristics
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double zone of B-hemolysis is produce by theta and alpha toxins
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Diagnostic tests for C. perfringens: reverse cAMP test
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Positive
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Diagnostic tests for C. perfringens: catalase?
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Negative
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Diagnostic tests for C. perfringens: Presence of PMNs in smears?
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Absent
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Diagnostic tests for C. perfringens: Gas production in tissues?
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Positive
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Diagnostic tests for C. perfringens: Nagler reaction for lecithinase neutralization with antitoxin?
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Positive
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C. Tetani: virulence factors:
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rapid sporulation, tentanolysin, tetanospasmin
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tetanolysin
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an oxygen labile hemolysin
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tetanospasmin
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an A-B toxin responsible for disruption of neurotransmitter release - spastic paralysis including RISUS SARDONICUS (facial paralysis)
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C. Tetani: diseases
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generalized tetanus, localized tetanus, cephalic tetanus (cranial nerve palsy), neonatal tetanus
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What group is most affected by tetanus?
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neonates
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What contributes to neonatal tetanus?
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unvaccinated mother, home delivery, unhygienic cutting of the umbilical cord, infectious substances applied to the umbilical stump
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C. bot: where found
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wound and food
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C. bot: general characteristics
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large fastidious, spore forming, anaerobic, rods, GRAM POSITIVE
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C. bot: function of the botulism toxin
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blocks neurotransmission, results in flaccid paralysis
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C. bot: most common population?
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infants
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