Chapter 21, part A

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings

PowerPoint® Lecture Slide Presentation prepared by Christine L. Case

MicrobiologyB.E Pruitt & Jane J. Stein

AN INTRODUCTIONEIGHTH EDITION

TORTORA • FUNKE • CASE

Chapter 21, part AMicrobial Diseases of the Skin and Eyes


Skin

• Salt inhibits microbes• Lysozyme hydrolyzes

peptidoglycan• Fatty acids inhibit

some pathogens

Figure 21.1


• Line body cavities• Epithelial cells attached to an extracellular matrix• Cells secrete mucus• Some have cilia

Mucous Membranes


• Gram-positive, salt-tolerant bacteria• Staphylococci• Micrococci• Diphtheroids

Normal Microbiota of the Skin

Figure 14.1a


• Exanthem• Skin rash arising from another focus of infection

• Enanthem• Mucous membrane rash arising from another

focus of infection

Microbial Diseases of the Skin


Microbial Diseases of the Skin

Figure 21.2


• S. epidermidis• Gram-positive cocci, coagulase-negative

• Staphylococcus aureus• Gram-positive cocci, coagulase-positive• Leukocidin• Exfoliative toxin

Staphylococcal Skin Infections



Figure 21.3



• Folliculitis• Infections of hair follicles

• Sty• Folliculitis of an eyelash

• Furuncle• Abscess; pus surrounded by inflamed tissue

• Carbuncle• Inflammation of tissue under the skin



• Impetigo of the newborn

• Toxemia

• Scalded skin syndrome

• Toxic shock syndrome

Figure 21.4


• Streptococcus pyogenes

• Group A beta-hemolytic streptococci

• M proteins

Streptococcal Skin Infections

Figure 21.5


• Erysipelas

• Impetigo

Streptococcal Skin Infections

Figure 21.6, 7


• Streptokinases• Hyaluronidase• Exotoxin A,

superantigen• Cellulitis• Necrotizing fasciitis

Invasive Group A Streptococcal Infections

Figure 21.8


• Pseudomonas aeruginosa• Gram-negative, aerobic rod• Pyocyanin produces a blue-green pus

• Pseudomonas dermatitis• Otitis externa• Post-burn infections

Infections by Pseudomonads


Calculate the relative risk to determine the most likely source of Pseudmonas dermatitis

Exposure Exposed Not Exposed(a) Have

Rash(b) No Rash (c) Have Rash (d) No Rash

Restaurant 18 11 1 1

Arcade 10 6 9 6

Swimming pool

17 1 2 11

Exercise room

11 5 8 7

Hot tub 18 2 1 10

e = aa + b f = c

c + d Relative Risk = ef


What was the mostly likely source of this outbreak of Pseudmonas dermatitis?

Exposure Relative Risk

Restaurant 1.24

Arcade 1.04

Swimming pool 6.14

Exercise room 1.29

Hot tub 9.90


• Comedonal acne• Occurs when sebum channels are blocked with shed

cells• Inflammatory acne

• Propionibacterium acnes• Gram-positive, anaerobic rod• Treatment:

• Preventing sebum formation (isotretinoin)• Antibiotics• Benzoyl peroxide to loosen clogged follicles• Visible (blue) light (kills P. acnes)

• Nodular cystic acne• Treatment: isotretinoin

Acne


• Papillomaviruses• Treatment:

• Removal• Imiquimod (stimulate interferon production)• Interferon

Warts

Chapter 21, part A

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