export_ssti bacteria iii Flashcards

1
Q

Clostridium features

A

Gram-positive
Spore forming

Anaerobic

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2
Q

Four major species of Clostridium

A

C. perfringens (gangrene, diarrhea)
C. difficile (diarrhea, colitis)

C. tetani (tetanus)

C. botulinum (botulism)

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3
Q

C. perfringens features

A

Produces hydrogen and CO2 gas

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4
Q

C. perfringens alpha-toxin

A

Phospholipase that hydrolyzes lecithin and sphingomyelin

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5
Q

Suppurative myositis

A

Inflammation of muscle

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6
Q

Myonecrosis

A

Destruction of muscle

Gas gangrene most notably with P. perfringens

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7
Q

Gas gangrene disease progression

A

Begins as cellulitis, progresses to suppurative myositis, then myonecrosis, then dissemination

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8
Q

Diagnose and treat C. perfringens

A

Gram-positive rods WITHOUT leukocytes
Treatment must be immediate, as fatality is high

Surgical debridement, clindamycin

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9
Q

C. tetani features

A

Strict anaerobe

“Drumstick” appearance

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10
Q

C. tetani entry

A

Small, local infection provides source for tetinospasmin to travel to CNS

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11
Q

Tetanospasmin

A

Heat liable neurotoxin
Inactivates inhibitory neurotransmitters, causing spastic paralysis

Rapidly degraded in GI, unlike botulinum

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12
Q

Three major presentation of C. tetani infection

A

Generalized
Localized

Neonatal

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13
Q

Generalized tetanus

A

Lock jaw
Back spasms

Autonomic involvement is most severe

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14
Q

Localized tetanus

A

Confined to muscles at site of inoculation

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15
Q

Neonatal tetanus

A

Infected umbilical stump

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16
Q

Risus sardonicus

A

Sustained contraction of fascial muscles

Caused by tetanospasmin

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17
Q

Opisthotonic posturing

A

Spinal muscles affected by tetanospasmin

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18
Q

Treat C. tetani

A

Debridement of primary wound

Human tetanus Ig

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19
Q

Prevent C. tetani infection

A

Immunize with boosters

20
Q

Mycobacterium features

A

Gram-positive, ACID-FAST, aerobic
Lipid-rich cell wall

Non-spore forming, non-motile

Slow growing

21
Q

Mycobacterial cell wall components

A

Mycolic acids

LAM

22
Q

LAM

A

Structurally and functionally related to LPS

23
Q

Mycobacterium diseases

A

TB (M. tuberculosis, M. bovis, M. kansasii)

Leprosy (M. leprae)

24
Q

Pott’s disease

A

Skeletal muscle TB

Upper lumbar and lower thoracic vertebrae most affected

25
Q

Diagnose Pott’s disease

A

Immunocompromised, developing countries
“Gibbus” deformity

Positive PPD test
Granulomas

26
Q

TB host response

A

Th1 produce IFN-gamma, which stimulate macrophages to kill

Mycobacterium resists macrophages, and is walled off in granuloma

27
Q

Treat Mycobacterium

A

Combination of four antibiotics over several months

28
Q

M. leprae features

A

Targets macrophages and Schwann cells

Only reservoirs are humans and armadillos

29
Q

Two diseases of M. leprae

A

Tuberculoid

Lepromatous

30
Q

Tuberculoid leprosy host response

A

Th1

31
Q

Lepromatous leprosy host response

A

Th2 response

Abs ineffective, results in Hansen’s disease

32
Q

Diagnose leprosy

A

Lepromin test

Culture is IMPOSSIBLE - biopsy can be done

33
Q

Treat leprosy

A

Prolonged treatment with uncommon antibiotics

34
Q

Nocardia features

A

Aerobic, Gram-positive rod (but doesn’t take up stain well)
Weakly acid fast

Filamentous (resembles hyphae)

Aerial hyphae

35
Q

Mycetoma

A

SSTI caused by nocardia
Slow progression, painless

Foot is the most common site

36
Q

Other diseases caused by nocardia

A

Lymphocutaneous disease

Cellulitis and subQ abscesses

37
Q

Diagnose and treat nocardiosis

A

Hx involving exposure from environment

Treat with TMP-SMX

38
Q

Actinomyces israellii

A

Filamentous bacteria
Strict anaerobe

Opportunistic pathogen

Abscesses contain sulfur granules

Associated with dental work

Control with penicillin

39
Q

Diagnose and treat Actinomyces

A

Filamentous biopsy
Differentiate from nocardia based on acid-fast stain

Penicillin

40
Q

Acne vulgaris infection

A

Pilosebaceous unit affected

41
Q

Four elements of acne vulgaris pathogenesis

A

Follicular epidermal hyperproliferation
Excess sebum production

Inflammation

Presence and activity of Propionibacterium acnes

42
Q

Propionibacterium acnes features

A

Gram-positive rod
Anaerobic

Stimulates inflammation

43
Q

Treat acne vulgaris

A
Topical first
Oral antibiotics (doxycycline)

Isotrenoid (Accutane)

44
Q

Gingivitis

A

Inflammation of gingiva

Reversible

45
Q

Periodontitis

A

Chronic inflammatory disease
Includes gingivitis along with loss of CT ad bone support for teeth

Irreversible

46
Q

Gingivits and periodontitis causes

A

Bacteria in the dental plaques

Create inflammatory response in gingival tissue

47
Q

Dental caries causative agent

A

Streptococcus mutans (Viridans strep.) is dominant cause - acid products is the underlying causes