Perspiration & Sebum contain

nutrients

salt inhibits

most microbes

Lysozyme hydrolyzes

peptidoglycan

fatty acids inhibit

some pathogens

Mucous Membranes:

• line body cavities (epithelial cells)
• are acidic
• have cilia

The outer portion of the skin (epidermis) contains:

keratin, a waterproof coating

Normal microbiota of the skin are gram(+) and salt tolerant:

• Staphylococci
• Micrococci
• Diptheroids

These anaerobes grow in hair follicles

Propionibacterium acnes

These aerobes grow on the skin surface

Corynebacterium xerosis

a yeast that grows on oily skin surfaces; cause of dandruff

Malassezia furfur

S. epidermidis

coagulase-negative

*the majority of skin microbiota*

S. aureus

coagulase-positive

S. aureus resistance:

• antibiotic-resistant
• lysozyme resistant
• resists opsonization (phagocytosis)

• leukocidin
• exfoliative toxin
• superantigen

S. aureus

Staph skin infections:

• folliculitis
• sty
• furuncle
• carbuncle
• impetigo

Folliculitis

• infections of the hair follicle

Sty

folliculitis of an eyelash

Furuncle

abscess

• pus surrounded by inflamed skin

Carbuncle

inflammation of the tissue under the skin

Impetigo

• crusting sores (nonbullous)
• spread by autoinoculation

Scalded Skin Syndrome (SSS)

• Bullous impetigo / Impetigo of a newborn

S. aureus

Toxic Shock Syndrome (TSS)

S. aureus

S. pyogenes

Group A beta-hemolytic streptococci

(GAS)

• S. pyogenes
• cause severe & rapid tissue destruction

S. pyogenes (GAS)

• hemolysins
• hyaluronidase
• streptolysins
• M proteins

Streptococcal TSS

SHOCK & ORGAN DAMAGE

Diseases caused by P. aeruginosa

• Otitis externa
• dermatitis
• burn infections
• respiratory infections

P. aeruginosa produces Pyocyanin

produces a blue-green pus

Buruli ulcer

Mycobacterium ulcerans

Buruli ulcer symptoms

• deep damaging ulcers
• exceeds incidence of leprosy

Viral disease of the skin:

• Warts
• Smallpox
• Monkeypox
• Chickenpox
• Shingles
• Herpes Simplex
• Measles (Rubeola)
• 5th Disease (Erythema Infectiosum)
• Roseola

Warts

Papillomaviruses

Treatment for Warts

Removal by:

• Cryotherapy
• Electrodessication
• Salicylic acid

Imiquimod, Bleomycin

Smallpox (variola)

orthopox virus

• erradicated by vaccination

Smallpox (variola) major ____% mortality

20% mortality

Smallpox (variola) minor ____% mortality

1% mortality

Chickenpox (varicella)

Varicella-zoster virus (HHV-3)

Chickenpox is transmitted

via respiratory route

Chickpox causes

pus filled vesicles

Chickenpox virus can lay dormant in

the dorsal root ganglia

The zoster-herpes virus, that affects the cutaneous sensory nerves

shingles

vaccine given to people who have been vaccinated for Chickenpox

Breakthrough varicella

Vaccination for Chickenpox

live attenuated vaccine

Herpes Simplex (HSV-1)

• oral & respiratory routes
• cold sores
• fever blisters

HSV-1: Herpes gladiatorum

vesicles on skin

HSV-1: Herpes whitlow

vesicles on fingers

HSV-2: Herpes encephalitis

• 70% fatality
• treatment - Acyclovir

HSV-1 remains dormant

trigeminal nerve

(facial nerve)

HSV-2 remains dormant in

sacral nerve ganglia

Measles (Rubeola)

• Measles virus
• transmitted via respiratory route

A rare complication of Measles:

Subacute Sclerosing PanEncephalitis (SSPE)

• 1 in 1,000,000 cases

Fifth Disease (Erythema Infectiosum)

HPV B19

• mild flu-like symptoms
• facial rash

List of skin rashes Fifth Disease derived from:

• Measles
• Scarlet Fever
• Rubella
• Filatov Dukes Disease

Roseola

HHV-6 & HHV-7

• fever, rash
• lasts 1-2 days

Cutaneous Mycoses

(ringworm, tineas)

Dermatomycoses

fungi that grow on keratin

Genera of cutaneous mycoses

• Trichophyton
• Microsporum
• Epidermophyton

Trichophyton

• hair
• skin
• nails

Microsporum

• hair
• skin

Epidermophyton

• skin
• nails

Treatment for cutaneous mycoses

• Miconazole
• Allylamine

Subcutaneous mycoses

Sporotrichosis

sporothrix schenchii

a fungus that penetrates the skin thru a wound

sporotrichosis

Sporotrichosis is treated with

potassium iodide (KI)

Candidiasis

candida albicans (yeast)

Candidasis occurs in

skin/ mucous membranes of GU tract & mouth

a yeast infection of the mucous in mouth

Thrush

Treatments for Candidasis

• Miconazole
• Nystatin

Systemic Candidasis is called

Fulminating Disease

Systemic Candidasis can be treated with

Fluconazole

Scabies

(Sarcoptes scabei)

• burrow in skin to lay eggs

Treatment for Scabies

topical insecticides

Pediculosis humanus capitas

head lice

Pediculosis humanus corporis

body lice

Pediculosis feed on

blood

Treatment for Pediculosis

topical insecticides

Diseases of the Eye:

• Conjunctivitis
• Ophthalmia neonatorum
• Chlamydia trachomatis

Conjunctivitis (pinkeye)

H. influenza

• unsanitary contact lens

Ophthalmia neonatorum

N. gonorrhoeae

• transmitted to baby's eye during birth
• treated with antibiotics at birth

Inclusion conjunctivitis (Chlamydia conjunctivitis)

Chlamydia trachomatis

• transmitted to baby's eye during birth
• spread thru swimming water

Treatment for conjunctivitis

Tetracycline

Trachoma

Chlamydia trachomatis

• causes permanent scarring of cornea

leading cause of worldwide blindness

Trachoma

What are the 2 bacterial Diseases of the eye that are transmitted to a newborn's eye during passage of the birth canal

1. Ophthalmia neonatorum
2. Chlamydia Conjuntivitis (inclusion)