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Flashcards in micro skin intro Deck (41):
1

skin normal flora:


skin pathogens:

Propionibacterium acnes.
diphtheroids.
coagulase-negative staphylococci.

P. aeruginosa in axilla, perineum

2

Nail or nail bed lesions

Distal subungual onychomycosis.
White superficial onychomycosis (Leukonychia mycotica).
Proximal subungual onychomycosis found in patients with

3

Agents of Nail or nail bed infections

Half caused by fungi.
Tinea unguium (Onychomycosis) Ringworm of the nails: Trichophyton rubrum and
T. metagrophytes account for 90% of dermatophytic nail infections, Epidermophyton
no hair the remainder

Paronychial or onychomycotic candidosis/ Candidal onychomycosis (NOT a
dermatophytic manifestation) Candida sp./C. albicans.

GNR (esp. P. aeruginosa).

4

agents of Stratum Cornium (color change) infection

Pityriasis versicolor/Tinea versicolor:
Malassezia furfur
Hortaea (Exophiala) werneckii

5

agents of Keratin Layer infections

(Highly variable; papulosquamous to vesicular):
Ringworm/Dermatophyte fungi:
Microsporum, Epidermophyton, Trichophyton

6

Agents of Epidermis Including Hair and Sebaceous Gland infections

Maculopapular which may become  vesicular:
-Erythema infectiosum: Parvovirus B19,
-Exanthem subitum: HHV6, HHV7,
-Measles/Rubeola: rubeola/measles virus
-3-day Measles/Rubella: rubella virus
-Enteroviral infections: ECHOvirus (enteric cytopathic human orphan virus – many [31] serotypes);Coxsackie viruses (A and B - many [30] serotypes;) Enteroviruses 68- 71
-Karposi sarcoma: HHV-8,
-Chicken pox-Shingles: Varicella zoster virus (HHV3)

7

MORE Agents of Epidermis Including Hair and Sebaceous Gland infections

-Cold Sores: HSV-1 and 2
-Scarlet fever: Streptococcus pyogenes,
-Bullous impetigo: Staphylococcus aureus
-Epidemic impetigo: (Staphylococcus aureus, Streptococcus pyogenes)
-Dermatomycosis: Cutaneous Candidiasis

8

Agents of Hair Endothrix or Ectothrix infections

-White Piedra: Trichosporon biegelii resembles nits and lice- Ectothrix
-Tinea capitis: Microsporum and Trichophyton spp.- Ectothrix
-Black Piedra: Piedra hortai (resembles endothrix of Trichophyton)
-Tinea favosa: Trichophyton – endothrix.

9

agents of Hair and face (bearded areas of face) infections

Tinea barbae (Barber’ s itch): anthropophilic strains of Trichophyton rubrum and zoophilic strains of T. mentagrophytes or T. verrucosum
Microsporum, Epidermophyton

10

agents of Hair and scalp infections

Tinea capitis (Ringworm of the scalp and hair): Microsporum or Trichophyton species. M. audouinii and M. canis are responsible for most infections in US.

11

agents of Hair and scalp or Hair and glabrous skin infections

Tinea favosa (Honeycomb ringworm) T. schoenleinii.

12

Dermis: Lymphatic infections

Cervicofacial lymphadenitis in children (Mycobacterium haemophilum).
Erysipelas (Streptococcus pyogenes)
Sporotrichosis (Sporothrix schenckii)
Onchocerciasis, or River Blindness (Onchocerca volvulus)

13

agents of Hair follicle and sebaceous gland with surrounding tissue (Pustular lesions) infections

Acne vulgaris - inflammatory: Propionibacterium acnes
Folliculitis (Superficial infection of individual hair follicle and apocrine regions): S. aureus, GNR, M. furfur
Furuncles( boils): S. aureus
Carbuncles: S. aureus
Small Pox: Variola major virus
Tinea barbae: Microsporum, Epidermophyton, Trichophyton

14

agents of Subcutaneous fat and tissue infection

Cellulitis: bacteria, fungi, viruses
Ecthyma: B-hemolytic Streptococcus pyogenes
Erysipelas: B-hemolytic Streptococcus pyogenes
Sporotrichosis: Sporothrix schenckii
Mycetoma: bacteria and fungi [large numbers of various microorganisms are associated
with mycetoma formation including Actinomyces israelii]).
Lobomycosis/Lobo’s Disease: Loboa loboi
Chromoblastomycosis: fungi
Phaeomycotic cysts: over 30 different fungal agents
Onchocerciasis, or River Blindness: Onchocerca volvulus

15

Fascia infections

necrotizing fasciitis: S. pyogenes; mixed anaerobic infection, etc.

16

muscle infections: myonecrosis

-Gas gangrene/clostridial myonecrosis: Clostridium perfringens, etc.
-Pyomyositis: pyogenic infection of striated muscle with abscess formation: S. aureus
-Trichniosis helminthic infection of striated muscle - Trichinella spiralis.
-Rhabdomyolysis infection of striated muscle: Legionella; pneumococcus,
influenzavirus

17

muscle infections: myopathy

Rheumatic fever: an autoimmune disease due to cross-reactive bacterial (GAS) antigens, acute RF can also involve myocardium, not just valves. *Second most commonly acquired-heart disease in US children*

Kawasaki disease (AKA mucocutaneous lymph node syndrome): an acute vasculitis of infants and young children. *Most commonly acquired-heart disease (aortic aneurism) in US children*

Infectious Endocarditis

18

Infectious disease of muscle (All are rare): Acute myopathy: viral etiology

Influenza virus A, B;
Coxsackieviruses A, B (esp. type B);
HIV;
Human Parvovirus B19,
Parainfluenzavirus
adenovirus
mumps
echoviruses
polio viruses
herpes simplex virus 2
Epstein Barr virus
CMV
Hepatitis A or C.

19

Infectious disease of muscle (All are rare): Acute myopathy: bacterial etiology

S. aureus.
Streptococcus pyogenes (GAS).
streptococcal &/or polymicrobic infections.
Clostridia perfringens, type A.
actinomycetes.
MTB.
M. leprae.
Lyme disease.
syphilis.
Legionella.
diphtheria (heart).

20

Infectious disease of muscle (All are rare): Acute myopathy: fungal etiology

candidiasis, coccidioidomycosis, sporotrichosis

21

Infectious disease of muscle (All are rare): Acute myopathy: protozoans

toxoplasmosis
schistosomiasis
Trypanosoma cruzi and the inflammatory disease of the heart associated with
Chagas’ disease.

22

Infectious disease of muscle (All are rare): Acute myopathy: Helminths

Trichinosis - Trichinella spiralis - LEARN,
cysticercosis
echinococcosis.

23

Infectious disease of muscle: pyomyositis

abscess formation in striated muscle: S. aureus.

24

Infectious disease of muscle: rhabdomyolysis:

a clinical syndrome characterized by muscle pain, release of creatine kinase and myoglobin from muscle caused by:

infection (bacterial, most commonly Legionella spp.; viral, e.g., influenzavirus).
trauma
hyperthermia
ischemia
drugs
toxin,
electrolyte disorders.

25

infections of muscle: Kawaski disease

vasculitis

26

infections of muscle: myonecrosis- LEARN

monomicrobic:
a. C. perfringens, type A
b. S. aureus
c. GAS

polymicrobic.

27

G- rods (anaerobic bacteria)

Aggregatibacter (AKA Actinobacillus actinomycetemcomitans;(obligate anaerobe).
Bacteroides fragilis, ureolyticus, forsythus (obligate anaerobe).
Bilophila wadsworthia (obligate anaerobe).
Fusobacterium spp. (obligate anaerobe long rods with tapered ends).
Pasteurella multocida, pestis.
Porphyromonas gingivalis (obligate anaerobe).
Prevotella intermedia (obligate anaerobe).

28

G- Cell Wall Architecture (anaerobic bacteria)

Spirochetes ( internal flagella):
Treponema denticola, T. vincentii (obligate anaerobes)

29

G+ cocci (anaerobic)

Enterococcus faecalis, faecium. (cocci in pairs and chains -
aerotolerant anaerobes).

Peptostreptococcus spp. (obligate anaerobic, cocci in chains) Taxonomic validity of
grouping agents anaerobic, cocci in chains in this genus is in doubt.

Streptococci (cocci in chains - aerotolerant anaerobes):
-Streptococcus agalactiae – Group B strep (GBS),  hemolytic.
-Streptococcus bovis (GIT streptococci),  hemolytic.
-Streptococcus mutans, sanguis, salivarius, mitis (oral streptococci).
-Streptococcus pneumoniae – (lancet shaped diplococci,  hemolytic)
-Streptococcus pyogenes – Group A strep (GAS),  hemolytic

30

G+ rods

Bifidobacterium spp. (obligate anaerobe).
Clostridium species (short rod, anaerobic, spore former[endosores])
a. C. perfringens, type A
b. C. septicum
c. C. noveyi
-Lactobacillus spp. (box-car shaped, aerotolerant anaerobe).
-Gram-positive, thin, branching filaments with clubbed ends (Actinomycetes):
-Clubbed-shaped rod -- Propionibacterium acnes (anaerobe).

31

Gram-positive cell wall structure but stain Gram-variableGram-negative:

Rods/pleomorphic shapes: Gardnerella vaginalis (obligate anaerobe).

Curved rods: Mobiluncus morphotypes/spp. (obligate anaerobe).

32

risk: Recurrent hospital admissions

MRSA

33

risk: Contact sports, recurrent boils/abscesses, visiting certain states in the USA

MRSA; MSSA producing Panton-Valentine leukocidin

34

risk: DM

MRSA; MSSA; group B streptococci; anaerobes; Gram- negative bacilli

35

risk: neutropenia

Gram-negative bacilli; Pseudomonas aeruginosa

36

risk: bite wounds

human: Human oral flora (Ekinella)
cat: Pasteurella multocida
dog: Capnocytophaga canimorsus
rat: Streptobacillus moniliformis (also consider tetanus and rabies)

37

risk: animal contact

Campylobacter spp.; dermatophyte infection; Bartonella henselae; Francisella tularensis; Bacillus anthracis; Yersinia pestis

38

risk: water exposure

Vibrio spp.; Aeromonas hydrophila; Mycobacterium marinum; Ps. aeruginosa

39

risk: reptile contact

Salmonella spp.

40

risk: IVDU

MRSA; Clostridium botulinum; Clostridium tetani

41

risk: Travel to tropical regions of Africa or America

Leishmaniasis; cutaneous larva migrans; myiasis;
Cordylobia anthropophaga; Dermatobia hominis

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