Microbial Diseases of the Microbial Diseases of the Skin and Eyes Skin and Eyes

SkinSkin

The skin is generally inhospitable to the growth ofThe skin is generally inhospitable to the growth of

certain microbes but supports the growth of somecertain microbes but supports the growth of some

SaltSalt inhibits microbes inhibits microbes

LysozymeLysozyme hydrolyzes peptidoglycan hydrolyzes peptidoglycan

Fatty acids inhibit some pathogensFatty acids inhibit some pathogens

Mucous MembranesMucous Membranes

Line body cavitiesLine body cavities Epithelial cells attached to an extracellular matrixEpithelial cells attached to an extracellular matrix Cells secrete mucusCells secrete mucus Some have ciliaSome have cilia

Normal Microbiota of the SkinNormal Microbiota of the Skin

Gram-positive, salt-tolerant bacteriaGram-positive, salt-tolerant bacteria

StaphylococciStaphylococci

MicrococciMicrococci

DiphtheroidsDiphtheroids Vigorous washing reduce but does not eliminate Vigorous washing reduce but does not eliminate

the the normal microbiotathe the normal microbiota

- microorganisms in hair follicles & sweat- microorganisms in hair follicles & sweat

glands reestablish normal population afterglands reestablish normal population after

washing.washing.

Increase number of microorganism in moistIncrease number of microorganism in moist

areas of the body ( Armpits )areas of the body ( Armpits )

Body OdorBody Odor

Microbial Diseases of the SkinMicrobial Diseases of the Skin

Skin lesions & rashes does not necessarilySkin lesions & rashes does not necessarily

indicate infections of the skin but maybe indicate infections of the skin but maybe

manifestations of systemic disease.manifestations of systemic disease. ExanthemExanthem

Skin rash arising from another focus of Skin rash arising from another focus of infectioninfection

EnanthemEnanthem

Mucous membrane rash arising from Mucous membrane rash arising from another another focus of infectionfocus of infection

BACTERIAL DISEASES OF THE SKINBACTERIAL DISEASES OF THE SKIN

Staphylococcus & StreptococcusStaphylococcus & Streptococcus

1. Come in contact with the skin & are 1. Come in contact with the skin & are

adopted to the skin’s physiologicadopted to the skin’s physiologic

conditionsconditions

2. Produce invasive & damaging 2. Produce invasive & damaging enzymesenzymes

Staphylococcal Skin InfectionsStaphylococcal Skin Infections

StaphylococcusStaphylococcus

- spherical, Gram- positive- spherical, Gram- positive

- irregular grape-like clusters- irregular grape-like clusters

Types of Staph. Types of Staph.

1. Coagulase-positive1. Coagulase-positive

- produces - produces CoagulaseCoagulase – an enzyme – an enzyme

that clots fibrin.that clots fibrin.

- fibrin clot protects the organism from- fibrin clot protects the organism from

phagocytosisphagocytosis

2. Coagulase- negative2. Coagulase- negative

- does not produce Coagulase- does not produce Coagulase

- 90% of skin normal flora- 90% of skin normal flora

- pathogenic only when skin barrier is- pathogenic only when skin barrier is

broken ( Insertion & removal of catheter)broken ( Insertion & removal of catheter)

Staphylococcus epidermidisStaphylococcus epidermidis- Gram-positive cocci, coagulase-negative- Gram-positive cocci, coagulase-negative- found in human skin- found in human skin- found in catheters surrounded by slime - found in catheters surrounded by slime

layer of capsular materiallayer of capsular material- protection against dessication &- protection against dessication &

disinfectiondisinfection Staphylococcus aureusStaphylococcus aureus

- Gram-positive cocci, coagulase-positive- Gram-positive cocci, coagulase-positive

- most pathogenic - most pathogenic - forms golden yellow colonies- forms golden yellow colonies

Toxins produced by Staph. Aureus:Toxins produced by Staph. Aureus:

1. Leukocidin1. Leukocidin

2. Exfoliative toxin2. Exfoliative toxin

3. Enterotoxin3. Enterotoxin

Problems in Staph. Infection:Problems in Staph. Infection:

1. Dangers to surgical wounds1. Dangers to surgical wounds

- S. aureus is carried by hosp. staff & - S. aureus is carried by hosp. staff &

visitorsvisitors

2. Antibiotic resistance2. Antibiotic resistance

- only 10% are sensitive to Penicillin- only 10% are sensitive to Penicillin

3. Favorarable environment provided by nasal3. Favorarable environment provided by nasal

passages passages

4. Hair follicles as reservoirs4. Hair follicles as reservoirs

Staphylococcal Skin Infections:Staphylococcal Skin Infections:1. 1. FolliculitisFolliculitis

- Infections of hair follicles- Infections of hair follicles

Sty Sty

Folliculitis of an eyelashFolliculitis of an eyelash Furuncle ( Boil )Furuncle ( Boil )

Abscess; pus surrounded by inflamed Abscess; pus surrounded by inflamed tissuetissue

CarbuncleCarbuncle

Inflammation of tissue under the skinInflammation of tissue under the skin

Impetigo of the newbornImpetigo of the newborn

- Stap. Aureus- Stap. Aureus

- thin walled vesicles on the skin that - thin walled vesicles on the skin that rapturerapture

& crust& crust

Scalded skin syndromeScalded skin syndrome

- Stap. aureus toxin entering the - Stap. aureus toxin entering the bloodstreambloodstream

- newborn or children below 3yrs. Old- newborn or children below 3yrs. Old

- lesions develop into a bright red area then- lesions develop into a bright red area then

peels off peels off

Streptococcal Skin InfectionsStreptococcal Skin Infections

StreptococcusStreptococcus

- gram- positive, spherical, in-chains- gram- positive, spherical, in-chains

- causes a wide range of disease- causes a wide range of disease

- produces & secretes toxins, enzymes &- produces & secretes toxins, enzymes &

virulence factorsvirulence factors

ToxinsToxins & Enzymes produced:& Enzymes produced:

1. Streptokinase1. Streptokinase

2. Hyaluronidase2. Hyaluronidase

3. Deoxyribonucleases3. Deoxyribonucleases

4. Leukocidins4. Leukocidins

5. Erythrogenic toxins5. Erythrogenic toxins

6. Exotoxin A6. Exotoxin A

Streptococcal Skin InfectionsStreptococcal Skin Infections1. Erysipelas1. Erysipelas

- Streptococcus pyogenes- Streptococcus pyogenes

- starts as sore throat skin erupts - starts as sore throat skin erupts intointo

reddish patchesreddish patches

with raisedwith raised

marginsmargins

2. Impetigo2. Impetigo

- seen in toddlers & adults- seen in toddlers & adults

- associated with Staph. Infection- associated with Staph. Infection

3. 3. CellulitisCellulitis

- infection of the connective tissue with- infection of the connective tissue with

inflammation of the subcutaneous layer.inflammation of the subcutaneous layer.

4. Myositis4. Myositis – infection of the muscles – infection of the muscles

5. Necrotizing fasciitis5. Necrotizing fasciitis- Infection of the deeper layer of the sub-Infection of the deeper layer of the sub-

cutaneuos tissue and into the fasciacutaneuos tissue and into the fascia

Infections by PseudomonadsInfections by Pseudomonads

PseudomonadsPseudomonads

- Gram-negative, aerobic rod- Gram-negative, aerobic rod

- Widespread in soil, water & soap- Widespread in soil, water & soap

- Resistant to most antibiotics & disinfectants- Resistant to most antibiotics & disinfectants

Pseudomonas aeroginosaPseudomonas aeroginosa

- opportunistic pathogen- opportunistic pathogen

- produces - produces Endotoxin PEndotoxin P

- implicated in most nosocomial infection- implicated in most nosocomial infection

- indwelling medical tubes & devices- indwelling medical tubes & devices

mops, vases & diluted disinfectantsmops, vases & diluted disinfectants

Diseases caused by Pseudomonas:Diseases caused by Pseudomonas:

1. Pseudomonas dermatitis1. Pseudomonas dermatitis

- self-limiting rash (2wks), swimming pools &- self-limiting rash (2wks), swimming pools &

saunassaunas

- enters through the hair follicles- enters through the hair follicles

2. Otitis externa / Swimmers ear2. Otitis externa / Swimmers ear

- infection of the external ear- infection of the external ear

3. Post-burn infections3. Post-burn infections

- Pyocyanin produces a blue-green pus- Pyocyanin produces a blue-green pus

Tx: FluoroquinolonesTx: Fluoroquinolones

Silver sulfadiazineSilver sulfadiazine

AcneAcne Comedonal acneComedonal acne

Occurs when sebum channels are blocked with Occurs when sebum channels are blocked with shed shed cellscells

Inflammatory acneInflammatory acnePropionibacterium acnesPropionibacterium acnes

Gram-positive, anaerobic rodGram-positive, anaerobic rodTreatment:Treatment:

Preventing sebum formation (isotretinoin)Preventing sebum formation (isotretinoin)AntibioticsAntibioticsBenzoyl peroxide to loosen clogged folliclesBenzoyl peroxide to loosen clogged folliclesVisible (blue) light (kills P. acnes)Visible (blue) light (kills P. acnes)

Nodular cystic acneNodular cystic acneTreatment: isotretinoinTreatment: isotretinoin

VIRAL DISEASES OF THE SKINVIRAL DISEASES OF THE SKIN

Warts / VerrucaWarts / Verruca

- - PapillomavirusesPapillomaviruses, benign skin growth, benign skin growth

- person to person contact, sexually- person to person contact, sexually

Tx: RemovalTx: Removal

- Cold liquid nitrogen, - Cold liquid nitrogen, ElectrodessicationElectrodessication

Acid burningAcid burning

PoxvirusesPoxviruses

Smallpox (Variola)Smallpox (Variola)

- - Smallpox virus (Orthopox virus)Smallpox virus (Orthopox virus)

Variola majorVariola major has 20% mortality has 20% mortality

Variola minorVariola minor has <1% mortality has <1% mortality

- transmitted by respiratory route & infects- transmitted by respiratory route & infects

internal organsinternal organs

- Eradicated- Eradicated

- bioterrorism- bioterrorism

HerpesvirusesHerpesviruses

Chicken pox / Varicella zosterChicken pox / Varicella zoster

- - Varicella-zoster virus/Human herpes virus Varicella-zoster virus/Human herpes virus 33

- mild childhood disease- mild childhood disease

- low mortality rate, high if contracted later - low mortality rate, high if contracted later inin

lifelife

- Mortality is due to complications- Mortality is due to complications

- Encephalitis & Pneumonia- Encephalitis & Pneumonia

- Serious fetal damage in 2% cases if it - Serious fetal damage in 2% cases if it

occurs during pregnancyoccurs during pregnancy

Respiratory route localizes in skin after 2wksRespiratory route localizes in skin after 2wks

Infected skin is vesicularInfected skin is vesicular then fills with pus thenthen fills with pus then rapturesraptures Scab HealScab Heal Starts in the trunk then spreads to the extremitiesStarts in the trunk then spreads to the extremities Virus may remain latent in dorsal root gangliaVirus may remain latent in dorsal root ganglia

- Central nerve gangliion- Central nerve gangliion- persists as viral DNA ( antibodies cannot- persists as viral DNA ( antibodies cannot

penetrate the CNS)penetrate the CNS)

Shingles / Herpes zosterShingles / Herpes zoster- Reactivation of latent HHV-3 releases viruses - Reactivation of latent HHV-3 releases viruses that move along peripheral nerves to skin. that move along peripheral nerves to skin.- latent Varicella-zoster virus located at the- latent Varicella-zoster virus located at the

Dorsal root ganglion ( spine)Dorsal root ganglion ( spine)

Reactivated ( decades later ) - StressReactivated ( decades later ) - Stress Low resistanceLow resistance

Virions produced by reactivated DNAVirions produced by reactivated DNA move down peripheral nervesmove down peripheral nerves

Cutaneous Sensory Nerves of the skinCutaneous Sensory Nerves of the skin

( SHINGLES)( SHINGLES)

-Vesicles similar to chicken pox-Vesicles similar to chicken pox

-Unilateral( follows the cutaneous nerves)-Unilateral( follows the cutaneous nerves)

- Waist, face, upper chest, back- Waist, face, upper chest, back

- Severe burning, stinging pain for - Severe burning, stinging pain for monthsmonths

to years ( Post Herpetic Neuralgia)to years ( Post Herpetic Neuralgia)

- Adults- Adults

Herpes simplex 1 and Herpes simplex 2Herpes simplex 1 and Herpes simplex 2

Human herpes virus 1 and HHV-2Human herpes virus 1 and HHV-2- Oral/Respiratory & Skin contact- Oral/Respiratory & Skin contact- Cold sores or fever blisters (vesicles on - Cold sores or fever blisters (vesicles on

lips)lips)1. HHV-11. HHV-1

- Subclinical, Infancy- Subclinical, Infancy- - Herpes gladiatorumHerpes gladiatorum (vesicles on skin)(vesicles on skin) Herpes whitlowHerpes whitlow (vesicles on fingers) (vesicles on fingers)

HHV-1 can remain latent in HHV-1 can remain latent in trigeminal nervetrigeminal nerve gangliaganglia

2. HHV-22. HHV-2

- Genital herpes, Sexual contact- Genital herpes, Sexual contact

- Herpes encephalitis (HHV-2 has up to a - Herpes encephalitis (HHV-2 has up to a 70% 70% fatality rate)fatality rate)

- HHV-2 can remain latent in sacral nerve - HHV-2 can remain latent in sacral nerve ganglia ganglia

TX: AcyclovirTX: Acyclovir

Men WomenMen Women

Measles (Rubeola)Measles (Rubeola)

Measles virusMeasles virus Transmitted by respiratory routeTransmitted by respiratory route Incubation period: 10-12 daysIncubation period: 10-12 days Infectious even before symptoms occurInfectious even before symptoms occur Humans are the only known reservoirs Humans are the only known reservoirs Macular rash Macular rash Koplik's spotsKoplik's spots

- lesions in the oral cavity- lesions in the oral cavity- tiny red patches with central white specks- tiny red patches with central white specks

on the oral mucosa opposite the molars.on the oral mucosa opposite the molars.

Symptoms develop like common coldsSymptoms develop like common colds

Macular rash starts on the face then spreads toMacular rash starts on the face then spreads to

the trunk & extremitiesthe trunk & extremities

Prevented by vaccinationPrevented by vaccination

MMRMMR

- given age 1 yr- given age 1 yr Complications:Complications:

1. Middle ear infection1. Middle ear infection

2. Pneumonia2. Pneumonia

3. Subacute sclerosing panencephalitis 3. Subacute sclerosing panencephalitis

- males- males

- 1-10 yrs. After recovery from - 1-10 yrs. After recovery from measlesmeasles

Rubella (German Measles)Rubella (German Measles)

Rubella virusRubella virus Respiratory routeRespiratory route Incubation period: 2-3 wksIncubation period: 2-3 wks Milder disease than Rubeola often goesMilder disease than Rubeola often goes undetectedundetected Macular rash and feverMacular rash and fever Congenital Rubella Syndrome Congenital Rubella Syndrome

- severe birth defect if during 1- severe birth defect if during 1stst trimester trimester- Deafness, cataract, heart defect, mental- Deafness, cataract, heart defect, mental

retardationretardation

A 1905 list of skin rashes included #1-measles, A 1905 list of skin rashes included #1-measles, #2-scarlet fever, #3-rubella, #4-Filatow-Dukes #2-scarlet fever, #3-rubella, #4-Filatow-Dukes (mild scarlet fever), and #5-(mild scarlet fever), and #5-

Fifth Disease / Erythema InfectiosumFifth Disease / Erythema Infectiosum

- Human parvovirus B19 - Human parvovirus B19

- mild flu-like symptoms- mild flu-like symptoms

- facial rash “ Slapped cheek”- facial rash “ Slapped cheek”

RoseolaRoseola

- Human herpesvirus 6 - Human herpesvirus 6

- high fever and rash, lasting for 1-2 days- high fever and rash, lasting for 1-2 days

- recovery leads to immunity- recovery leads to immunity

FUNGAL DISEASES OF THE SKIN &FUNGAL DISEASES OF THE SKIN &NAILSNAILS

Cutaneous MycosesCutaneous Mycoses Dermatomycoses:Dermatomycoses: Tineas or Ringworm Tineas or Ringworm

Metabolize keratin Metabolize keratin

TrichophytonTrichophyton infects hair, skin, nails infects hair, skin, nails

EpidermophytonEpidermophyton infects skin and nails infects skin and nails

Microsporum Microsporum infects hair and skin infects hair and skin Treatment:Treatment:

Oral griseofulvinOral griseofulvin

Topical miconazoleTopical miconazole

CandidiasisCandidiasis

Candida albicans (yeast)Candida albicans (yeast) CandidiasisCandidiasis may result from suppression of may result from suppression of

competing bacteria by antibioticscompeting bacteria by antibiotics Occurs in skin; mucous membranes of Occurs in skin; mucous membranes of

genitourinary tract and mouthgenitourinary tract and mouth Thrush is an infection of mucous membranes of Thrush is an infection of mucous membranes of

mouthmouth Topical treatment with miconazole or nystatinTopical treatment with miconazole or nystatin

Microbial Diseases of the EyeMicrobial Diseases of the Eye

Conjunctivitis (pinkeye)Conjunctivitis (pinkeye)

- - Haemophilus influenzaeHaemophilus influenzae

- Various microbes- Various microbes

- Associated with unsanitary contact lenses- Associated with unsanitary contact lenses Neonatal gonorrheal ophthalmiaNeonatal gonorrheal ophthalmia

- - Neisseria gonorrhoeaeNeisseria gonorrhoeae

- Transmitted to newborn's eyes during - Transmitted to newborn's eyes during passage through the birth canal passage through the birth canal

- Prevented by treatment newborn's eyes - Prevented by treatment newborn's eyes with with antibiotics / Silver nitrate antibiotics / Silver nitrate

Chlamydia trachomatisChlamydia trachomatis

Inclusion conjunctivitisInclusion conjunctivitis

- Transmitted to newborn's eyes during - Transmitted to newborn's eyes during passage through the birth canal passage through the birth canal

- Spread through swimming pool water- Spread through swimming pool water

- Treated with tetracycline- Treated with tetracycline

TrachomaTrachoma

- Greatest cause of blindness worldwide- Greatest cause of blindness worldwide

- Infection causes permanent scarring; - Infection causes permanent scarring; scars abrade the cornea leading to scars abrade the cornea leading to blindness blindness

Herpetic KeratitisHerpetic Keratitis

- Herpes simplex virus 1 (HHV-1)- Herpes simplex virus 1 (HHV-1)

- Infects cornea, may cause blindness- Infects cornea, may cause blindness

- Treated with trifluridine- Treated with trifluridine Acanthamoeba keratitisAcanthamoeba keratitis

- Transmitted from water- Transmitted from water

- Associated with unsanitary contact lenses- Associated with unsanitary contact lenses