Module 5: Chapter 16

Question 1

16.1 The Skin and its Defenses

Question 2

the skin, together with the nails, hair, sweat and oil glands, forms the ___________ system.

Answer 2

integument

Question 3

total surface area of skin

Answer 3

1.5-2 square meters

Question 4

layers of skin from outer to inner

Answer 4

epidermis (stratum corneum) -> dermis -> subcutaneous layer

Question 5

composition of the epidermis (four or five distinct layers)

outer to inner

Answer 5

stratum corneum (dead cells that have migrated from the deeper layers - packed with keratin, layer replaced every 25-45 days)

below the stratum corneum are three or four more layers of epithelial cells

the lowest layer, stratum basale or basal layer: attached to the underlying dermis and is source for all of the cells that make up the dermis

Question 6

importance of keratin

Answer 6

gives epithelial cells ability to withstand abrasion, damage, and water penetration

Question 7

thickest skin is found on the _____________ and the thinnest is on the __________

Answer 7

1. plantar of the foot

2. eyelids

Question 8

dermis layer (middle layer)

Answer 8

composed of connective tissue (instead of epithelium)

• means it is rich in fibroblast cells and fibers such as collagen
• contains macrophages and mast cells
• harbors a dense network of nerves, blood vessels, and lymphatic vessels

—> damage to the epidermis generally does not result in bleeding, whereas damage deep enough to the dermis results in broken blood vessels.

*blister formation, the result of friction trauma, or burns, represents a separation between the dermis and epidermis

—> roots of hair are housed in follicles in the dermis, sebaceous oil glands and sweat glands are also in the dermis

Question 9

____________ of cells from the stratum corneum slough off every day, and attached microorganisms are also sloughed off

Answer 9

millions

Question 10

one of the most effective defenses of the skin is a class of molecule called \_\_\_\_\_\_\_\_\_\_ \_\_\_\_\_\_\_\_\_\_. 
---> they are positively charged chemical that act by disrupting the negatively charged membranes of bacteria; chiefly responsible for keeping the antimicrobial count on skin relatively low

Answer 10

antimicrobial peptides

Question 11

sebum

Answer 11

low pH, oil-based secretion of the sebaceous glands (due to high concentration antibodies); makes the skin inhospitable to many microorganisms

Question 12

lipids in sebum can serve as nutrients for normal microbiota, but breakdown of the fatty acids contained in lipids leads to toxic by-products that do what?

Answer 12

inhibit the growth of microorganisms not adapted to the skin environment

Question 13

why is sweat inhibitory to microorganisms?

Answer 13

because of its low pH and its high salt concentration

—> lysozyme is an enzyme found in sweat (and tears and saliva) that specifically breaks down peptidoglycan

Question 14

16. 1 outcomes
17. describe the important anatomical features of the skin
18. list the natural defenses present in the skin

Answer 14

1. keratin in the epidermis - protects the skin from damage, abrasion, and water penetration
   - collagen in the dermis for withstanding stretching
2. -antimicrobial peptides
   -low pH (sweat)
   -sebum
   -high salt and lysozyme in sweat
   sloughing off of microbes from stratum corneum

Question 15

16.2 Normal Biota of the Skin

Question 16

microbes that live on the surface of the skin must be capable of living in what conditions that are on the skin?

Answer 16

salty and dry conditions

Question 17

microbes can grow into dense populations in what places

Answer 17

moist areas and skin folds such as the underarm and groin areas

Question 18

normal microbiota also live in the protected environment of the ________ follicles and ______ ducts

Answer 18

hair

glandular

Question 19

fascinating info about skin normal biota

Answer 19

hundreds of species of microbes including well known pathogens inhabit out epidermis, dermis, and subcutaneous skin layers

also common for different species to favor different areas of our bodies, and for different people to have different species

—> seems common for an individual’s microbiota to remain relatively constant over time

Question 20

common fungal colonizers of skin

Answer 20

dermatophytes

Question 21

skin defenses

Answer 21

keratinized surface, sloughing, low pH, high salt, lysozyme, antimicrobial peptides

Question 22

normal biota of skin

Answer 22

Streptococcus, Staphylococcus, Corynebacterium, Propionibacterium, Pseudomonas, Lactobacillus; yeasts such as Candida

Question 23

16. 2 outcomes

1. list characteristics of the skin’s normal microbiota

Answer 23

• hundreds of species of microbes including some pathogens inhabit the epidermis, dermis, and subcutaneous skin layers
• different species favor different areas of the body
• different people have different species
• common for individuals’ microbiota to remain relatively constant over time

Question 24

16.3 Skin Diseases Caused by Microorganisms

Question 25

Methicillin-resistant Staphylococcus Aureus (MRSA)

Answer 25

common cause of skin lesions in non-hospitalized people, and hospitalized patients are more likely to acquire systemic infections, bloodstream infections from MRSA)

-even though the name mentions methicillin, the stain is resistant to multiple antibiotics

Question 26

Staphylococcus aureus r/t MRSA

Answer 26

S. aureus- gram-pos coccus, nonmotile

• much of its destructiveness is due to its array of superantigens
• can be highly virulent BUT also appears as normal biota on the skin of one third of the population

-strains that are methicillin-resistant also found on healthy people

• considered the sturdiest of all non-endospore-forming pathogens
• –> well-developed capacities to withstand high salt (7.5%-10%), extremes in pH, and high temps (60degrees C for 60 minutes)
• –> also remains viable after months of drying and resists the effect of many disinfectants and antibiotics

Question 27

signs + symptoms of MRSA

Answer 27

infections of the skin tend to be raised, red, tender, localized lesions, often featuring pus, and feeling hot to the touch
—> may localize around a hair follicle

*fever is a common feature

Question 28

transmission and epidemiology of MRSA

Answer 28

common contaminant of all kinds of surfaces you touch daily; on gym equipment, shavers, airplane tray tables, electronic devices

Question 29

Pathogenesis and Virulence Factors of MRSA (S. aureus)

Answer 29

all pathogenic S. aureus strains typically produce coagulase, an enzyme that coagulates plasma (highly diagnostic species characteristic)

other enzymes expressed by S. aureus include hyaluronidase (digests intracellular “glue”), staphylokinase (digests blood clots), nuclease (digests DNA), and lipases that help bacteria colonize oily skin surfaces

Question 30

Culture and dx of MRSA

Answer 30

PCR is routinely used to diagnose

• alternatively cultivation on blood agar is useful for dx
• for heavily contaminated specimens, selective media such as mannitol salt agar are used
• the production of catalase, an enzyme that breaks down hydrogen peroxide accumulated during oxidative metabolism, can be used to differentiate the staphylococci, which produce it, from the streptococci which do NOT
• key technique for separating S. aureus from other species of Staphylococcus is the coagulase test: by definition any staph isolate that coagulates plasma is S. aureus, all others are coagulase-negative

Question 31

Prevention and Tx of MRSA

Answer 31

prevention is only possible with good hygiene

• tx of infection often starts with incision of the lesion and drainage of pus
• antimicrobial tx should include more than one antibiotic (current rec’d in US: vancomycin, linezolid, or daptomycin)

Question 32

summary of MRSA (gram +)

Answer 32

• most common modes of transmission: direct contact, indirect contact
• virulence factors: coagulase, other enzymes (staphylokinase etc.), superantigens
• culture/diagnosis: PCR, culture and gram stain, coagulase and catalase tests, multitest systems
• prevention: hygiene practices
• tx: vancomycin, linezolid, or daptomycin; serious threat in CDC Ant. Resistant Report
• epidemiology: community associated MRSA infections most common in children and young to middle aged adults; incidence increasing in community/decreasing in hospitals

Question 33

Maculopapular Rash Diseases:

Measles (Rubeola)

Answer 33

-hundreds of thousands of children die every year, despite there being a vax

• signs & sx: sore throat, dry cough, headache, lymphadenitis, and fever; Koplik’s spots = oral lesions that appear as prelude to characteristic red maculopapular exanthem (an eruption of rash) that erupts on the head then progresses to the trunk and extremities + whole body covered
• Subacute Sclerosing Panencephalitis (SSPE), a progressive neurological degeneration of the cerebral cortex, white matter, and brain stem (incidence: 1 in less than a thousand in children who get measles before getting vaccinated)
• pathogenesis & virulence factors: virus implants in the resp mucosa and and infects the tracheal and bronchial cells -> travels to the lymphatic system where it multiplies and and then enters the bloodstream, a condition known as viremia
• -> the virus induces cell membranes of adjacent host cells to fuse into large syncytia (cells will no longer perform reg fx)
• -> virus disables cell-mediated immunity and delayed-type hypersensitivity
• -> tends to erase or diminish the immune system’s memory for the microbes
• transmission & epidemiology: measles is one of the most contagious infectious diseases, transmitted principally by resp droplets; human is only reservoir
• -> person is infectious during the periods of incubation, prodrome phase, and the skin rash but usually not during the convalescence phase
• culture & dx: disease can be diagnosed on clinical presentation alone, but if further identification is required an ELISA test is available that tests for pt IgM to measles antigen BUT PCR is also available
• prevention: MMR vaccine = contains live attenuated measles virus, ProQuad vax
• treatment: relies on reducing fever, suppressing cough, and replacing lost fluid
• -> complications require additional remedies to relieve neurological and resp sx and to sustain nutrient, electrolyte, and fluid levels
• -> vit A supplements recommended by some MDs

Question 34

Maculopapular Rash Diseases:

Rubella (latin for “little red”)

Answer 34

• relatively minor rash disease with few complications “3 day measles”
• -> exception is when in utero and can cause damage to fetus (women of childbearing years must be vaccinated before they plan to concieve)
• s&s: two clinical forms: postnatal infection (children or adults) and congenital infection (infection of fetus, expressed in the newborn as various types of birth defects)
• –>postnatal: rash of pink macules and papules first appears on face and progresses down trunk+extremities, resolving in about 3 days; adult rubella s often characterized by joint inflammation and pain rather than rash
• –>congenital: teratogenic virus; in first trimester = miscarriage/multiple permanent defects in newborn; cardiac abnormalities, ocular lesions, deafness, and mental/physical retardation in varying combinations

-causative agent: virus is Rubivirus in family Togaviridae; stops MITOSIS, induces APOPTOSIS, damages vascular endothelium (poor development of organs)

• transmission & epidemiology: contact with resp secretions and sometimes urine; virus spread through prodromal phase and up to a week after rash appears
• congenitally infected infants are contagious for a much longer period of time
• culture & dx: it mimics other diseases, so should not be diagnosed on clinical grounds alone; IgM antibody to rubella virus can be detected early using an ELISA technique or a latex-agglutination card
• prevention & treatment: attenuated rubella virus vaccine is usually given to children in the combined form of MMR or MMRV vax. at 12-15 months and a booster at 4-6 years years of age.

Question 35

Maculopapular Rash Diseases:
Fifth Disease (erythema infectiosum)

Answer 35

Causative Organism(s): Parvovirus B19
Most Common Modes of Trans: droplet contact; direct contact
Virulence Factors: —
Culture/Dx: usually diagnosed clinically
Prevention: —
Treatment: —
Distinguishing Features of Rash: “slapped face”; rash first, within two days spreads to limbs and trunk, tends to confluent rather than distinct bumps
Epidemiological Features: 60% of population seropositive by age 20; very contagious
Appearance of lesions: see picture in text (table 16.2)

Question 36

Maculopapular Rash Diseases:

Roseola (“sixth disease”)

Answer 36

Causative Organism(s): Human herpesvirus 6
Most Common Modes of Trans: unknown
Virulence Factors: ability to remain latent
Culture/Dx: usually diagnosed clinically
Prevention: —
Treatment: —
Distinguishing Features of Rash: high fever (105F) precedes rash stage; rash not always present (up to 70% of cases proceed without rash)
Epidemiological Features: nearly 100% seropositive; 90% of disease cases occur before age 2; common in young children/babies
Appearance of lesions: see picture in text (table 16.2)

Question 37

Maculopapular Rash Diseases:

Other conditions to consider (covered in later chapters)

Answer 37

Zika virus disease
Scarlet fever
Secondary syphilis
Rocky Mountain spotted fever

Question 38

Impetigo

“I-pet-and-skin-go”

Answer 38

superficial bacterial infection that causes the skin to flake and peel off

• not serious, but highly contagious (especially in children)
• can be caused S. aureus or Streptococcus pyogenes, or a mixture, or S. aureus takes over after a while

Trans: direct contact; fomites; mechanical vector transmission

Prevention: good hygiene

S & S: the lesion looks variously like peeling, crusty, and flaky scabs, or honey-colored crusts; found around face, mouth, extremities, anywhere on skin; very SUPERFICIAL and itches

• what complication is associated with untreated impetigo?
• glomerulonephritis

Question 39

Impetigo caused by Staphylococcus aureus (gram +)

Answer 39

virulence factors: exotoxins called exfoliative toxins A and B, which are encoded by a phage that infects some S. aureus strains

Transmission: direct and indirect contact

Virulence Factors:

• at least one of the toxins attacks a protein that is very important for epithelial cell-to-cell binding in the outermost layer of the skin; breaking up the protein=blistering of the skin and the breakdown of skin = spread of bacterium
• coagulase; other enzymes

Culture/Diagnosis: routinely based on clinical signs; when necessary, culture and Gram Stain, coagulase and catalase tests, multitest systems PCR

Prevention: hygiene

Tx: no tx in uncomplicated cases; topical ointments

Distinguishing Features: seen more often in older children, adults

Epidemiological Features: incidence approx. 2-5% in children in temperate climates; higher in tropical areas

Question 40

Impetigo caused by Streptococcus pyogenes (gram +)

Answer 40

Most Common Trans: direct and indirect contact
Virulence Factors: Streptokinase, plasminogen-binding ability; hyaluronidase, M protein
Culture/Dx: routinely based on clinical signs; when necessary, culture and Gram stain, coagulase and catalase tests, mutlitest systems, PCR
Prevention: hygiene
Tx: uncomplicated cases= no treatment; topical mupirocin or retapamulin; concerning threat
Distinguishing Features: Seen more often in newborns
Epidemiological Features: incidence approx. 2-5% of children in temperate climates; higher in tropical areas

• beta-hemolytic on blood agar
• S. pyogenes also caused Streptococcal pharyngitis (strep throat), scarlet fever, serious bloodstream infections, and poststreptococcal conditions such as rheumatic fever, and poststreptococcal glomerulonephritis

Question 41

Cellulitis

Answer 41

Causative Organism(s): 1. Streptococcus pyogenes (G+), 2. MRSA (G+), 3. other fungi or bacteria

Most Common Trans: Parenteral implantation

Virulence Factors:

1. Streptokinase, plasminogen-binding ability, hyaluronidase, M protein
2. Exfoliative toxin - A, coagulase, other enzymes

Culture/Dx: Based on clinical signs

Prevention: —

Tx:

1. Oral or IV antibiotic (penicillin); surgery sometimes necessary; erythromycin-resistant Streptococcus pyogenes = concerning threat
2. Oral or IV antibiotic (cefazolin, ceftriaxone, vancomycin, linezolid); surgery sometimes necessary; MRSA = serious threat
3. Aggressive treatment with oral or IV antibiotic; surgery sometimes necessary

Distinguishing Features: 1. — 2. — 3. More common in immunocompromised

Epidemiological Features: Incidence highest among males 45-64

S & S: pain, tenderness, swelling, and warmth; fever and swelling of the lymph nodes may also occur, lymphangitis (red lines leading away from the area affected)

Question 42

Staphylococcal Scalded Skin Syndrome (SSSS)

Answer 42

Causative Organism(s): Staphylococcus aureus B (G+)

Most Common Trans: direct contact, droplet contact

Virulence Factors: Exfoliative toxins A and B

Culture/Dx: histological sections; cultures performed but false negatives common because toxins alone are sufficient for disease

Prevention: eliminate carriers in contact with neonates

Tx: immediate systemic antibiotics (current rec: cloxacillin)

Distinguishing Features: split in skin occurs WITHIN epidermis; exfoliative toxins cause bullous lesions (fluid-filled blisters)

Epidemiological Features: mortality 1-5% in children; 50-60% in adults

• carriers can harbor bacteria in the nasopharynx, axilla, perineum, and vagina
• most common in newborns and babies

Question 43

Scrum Pox: Herpes Gladiatorum

Answer 43

often spread at the gym or by athletes such as wrestlers or rugby players
once infected = infected for life
direct contact spread, and indirect (fomites)

Question 44

Vestibular or Pustular Rash Diseases:

Chicken Pox

Answer 44

Causative Organism(s): Human herpesvirus 3 (varicella-zoster virus)

Most Common Trans: droplet contact, inhalation of aerosolized lesion fluid

Virulence Factors: Ability to fuse cells, ability to remain latent in genitalia

Culture/Dx: based largely on clinical appearance; PCR available

Prevention: live attenuated vaccine; there is also vaccine to prevent latent virus (shingles)

Tx: uncomplicated cases= no treatment; acyclovir for high risk

Distinguishing Features: no fever prodrome; lesions are superficial and in CENTRIPETAL distribution (more in center of body)

Epidemiological Features: Chickenpox: vaccine decreased hospital visits by 88%, ambulatory visits by 59%

• incubation period of 10-20 days, first symptoms are fever and an abundant rash that begins on the scalp, face, and trunk and radiates to the extremities
• –> skin lesions progress quickly from macules and papules to itchy vesicles filled with clear fluid, in days they will encrust and drop off

Question 45

Vesicular or Pustular Rash Diseases:

Smallpox

Answer 45

Causative Organism(s): Variola virus (enveloped DNA virus)

Most Common Trans: primarily droplet contact, indirect contact (fomites)

Virulence Factors: ability to dampen and/or avoid immune response

Culture/Dx: based largely on clinical appearance; if suspected refer to CDC

Prevention: live virus vaccine (vaccinia virus)

Tx: Tecovirimat, cidofovir (drugs)

Distinguishing Features: fever precedes rash, lesions are deep and in CENTRIFUGAL distribution (more on extremities)

Epidemiological Features: last natural case worldwide was in 1977; Category A Bioterrorism Agent

• S & S: infection begins with fever and malaise and later a rash begins in the pharynx, spreads to the face, and progresses to extremities
• –> initially rash is macular-> papular-> vesicular-> and pustular before eventually crusting -> SCARRING

*two principal forms of smallpox: variola minor and variola major (major is highly virulent form that causes toxemia, shock, and intravascular coagulation

—> those who survived smallpox nearly always develop LIFELONG IMMUNITY

Question 46

Shingles (latent chickenpox)
enveloped DNA virus
—> humans are only natural hosts for HHV-3

Answer 46

after recuperation from chickenpox, the virus enters into the sensory nerve endings of cutaneous spinal nerve branches, especially those that serve the skin of the chest and head
—> becomes latent in the ganglia and may reemerge as shingles (herpes zoster); characteristics asymmetrical distribution on the skin of the trunk or head

How does shingles develop: psychological stress, x-ray tx, immunosuppressive and other drug therapy, surgery, or a developing malignancy.

Virulence Factors: —> HHV-3 enters resp tract, attaches to resp mucosa, and then invades the bloodstream

• –> viremia disseminates the virus to the skin where the virus causes adjacent cells to fuse and eventually lyse, resulting in characteristic lesions
• –> the virus enters the sensory nerves at this site, traveling to the dorsal root ganglia

Prevention: live attenuated vaccine: Zostavax and Shingrix

Question 47

Variola Major (small pox) early signs

Answer 47

prodrome: high fever, malaise, rash emerges (first in the mouth); sometimes severe back and abdominal pain accompany this phase
- within 24 hours a rash appears and spreads throughout the body

by day 3 or 4 of the rash, the bumps become bigger and fill with thick opaque fluid
DISTINGUISHING FEAT: pustules are indented in the middle, and patients report feeling like there is a BB pellet in the middle

after two weeks most lesions will crust over —> patient remains contagious until last scab falls off b/c crusts contain the virus
—>lesions occur at the dermal level

—> patient ill during entire rash phase

Question 48

Variola minor (small pox)

Answer 48

has a rash that is less dense (than variola major) and is generally less ill then someone with variola major

Question 49

Large Pustular Skin Lesions

Leishmaniasis

Answer 49

Causative Organism(s): Leishmania spp. (protozoan)

Most Common Trans: biological vector (sand fly)

Virulence Factors: Multiplication within macrophages

Culture/Dx: usually microscopic visualization

Tx: sodium stibogluconate, pentamidine

Prevention: avoiding sand fly
—> no vaccine, avoidance of female sand flies is only prevention

Distinguishing Features: mucocutaneous and systemic forms

Epidemiological Features: untreated visceral leishmaniasis mortality rate is 100%; 10% for cutaneous leishmaniasis

—> no vaccine, avoidance of female sand flies is only prevention

Cutaneous leishmaniasis: localized infection of the capillaries of the skin caused by L. tropica

Question 50

Large Pustular Skin Lesions

Cutaneous Anthrax

Answer 50

• most common form and least dangerous version of infection with Bacillus anthracis
• –>caused by endospores entering the skin through small cuts or abrasions
• –> marked by production of a papule that becomes increasingly necrotic and later ruptures to form a painless black ESCHAR (dark, sloughing scab)

Causative Organism(s): Bacillus anthracis bacteria (G+)

Most Common Form of Trans: direct contact with endospores

Virulence Factors: endospore formation; capsule, lethal factor, edema factor

Culture/Dx: culture on blood agar; serology, PCR performed by CDC

Prevention: avoid contact; vaccine available but not widely used (rec’d only for high risk person and the military)

Tx: Ciprofloxacin, plus two additional antibiotics

Distinguishing Features: can be fatal

Epidemiological Features: untreated cutaneous mortality rate: 20%; treated mortality rate less than 1%; CATEGORY A BIOTERRORISM AGENT

Question 51

Cutaneous and Superficial Mycoses (fungal infection)

Ringworm

Question 52

group of fungi that cause infections of the skin and other integument components; they survive by metabolizing keratin

Answer 52

dermatophytes

Question 53

dermatophytes also _______ the immune system and its ability to respond to them

Answer 53

suppress

Question 54

transmission of ringworm

Answer 54

direct or indirect contact with humans or animals, some fungi can be acquired from the soil

Question 55

treatment for ringworm

Answer 55

ointments containing tolnaftate, miconazole, itraconazole, terbinafine, or thiabendazole are applied regularly for several weeks

Question 56

superficial mycoses

Answer 56

fungal infection involving the outer epidermal surface

endogenous (normal biota)

caused by Malassezia species

culture/dx: usually clinical; KOH can be used (potassium hydroxide)

no prevention
highest incidence among adolecscents

topical antifungals are tx

Question 57

16.4 the surface of the eye and its defenses

Question 58

conjunctiva

Answer 58

thin fluid-secreting tissue that covers the eye (except for the cornea) and lines the eyelid

—>secretes and oil and mucus containing fluid that lubricates and protects the eye surface

Question 59

cornea “windshield of the eye”

Answer 59

dome shaped central portion of the eye lying over the iris (colored portion of the eye)

—> has five to six layers of epithelial cells that can regenerate quickly of they are superficially damaged

Question 60

eye’s best defense

Answer 60

tears, which consist of an aqueous fluid, oil, and mucus (formed in the lacrimal gland)

Question 61

make up of tears

Answer 61

sugars, lysozyme, and lactoferrin

*last two have antimicrobial properties

Question 62

why does inflammation not occur in the eye

Answer 62

b/c it hinders vision, flooding the eye with lymphocytes and macrophages would cause blurred vision

Question 63

eyes are not covered by __________ epithelium

Answer 63

keratinized

Question 64

eye and immune privilege

Answer 64

the restriction or deduction of immune response in certain areas of the body that reduces the potential damage to tissues that a normal inflammatory response could cause

—> evolution of vertebrate eye has been toward reduced innate immunity and a corresponding inflammatory response as it harms the function of the eye

Question 65

16.5 normal biota of eye

Question 66

in many cases, ____________ is the most dominant genus of the eye

Answer 66

Corynebacterium

Question 67

16S rRNA analysis of the healthy eye microbiome has revealed a more _______ population, showing high _______ in the bacteria found

Answer 67

robust

diversity

Question 68

the microbiome of the eye can be compared to that of the ____.

Answer 68

skin

Question 69

defenses of the eye

Answer 69

mucus in conjunctiva and in tears

lysozyme and lactoferrin in tears (antimicrobial properties + flushing)

Question 70

16.6 Eye diseases caused by microorganisms

Question 71

injection of the conjunctiva

Answer 71

conjunctivitis - relatively common
caused by specific microorganisms that have a predilection for eye tissues, by contaminants that proliferate due to the presence of a contact lens or an eye injury, or by accidental inoculation of the eye by a traumatic event

Question 72

signs and sx of conjunctivitis

Answer 72

many different clinical presentations

• most bacterial infections produce a milky discharge
• viral infections tend to produce a clear watery exudate

—>typical for patient to wake up in the morning with eye “glued” shut by secretions

—>sometimes caused by allergic response and often produce clear fluid as well

Question 73

pink eye or

Answer 73

conjunctivitis

Question 74

viral conjunctivitis is commonly caused by ____________, and is more common in _________ whereas bacterial conjunctivitis is more common in ________.

Answer 74

1. adenoviruses
2. adults
3. children

Question 75

keratitis (more serious than conjunctivitis)

Answer 75

when damage of deeper eye tissues occurs and can lead to complete corneal destruction

—> any microorganism can cause this condition, especially after trauma to the eye

Question 76

cause of herpetic keratitis

Answer 76

a misdirected reactivation of oral herpes simplex virus type 1; upon reactivation it travels into the ophthalmic region instead of mandibular branch of the trigeminal nerve

Question 77

amoeba called _______________ has been causing serious cases of keratitis, especially in those who where contact lenses

Answer 77

Acanthamoeba

Question 78

treatment for HSV keratitis

Answer 78

topical trifluridine and/or oral acyclovir

Question 79

S. aureus and MRSA produce enzymes that breakdown ______ ______

Answer 79

hydrogen peroxide

Question 80

out of measles, rubella, leishmaniasis, and impetigo, which is most likely to be a polymicrobial infection

Answer 80

impetigo

Question 81

steps of diagnostic process in order

Answer 81

anatomic diagnosis, differential diagnosis, etiologic diagnosis

ADE

Question 81

steps of diagnostic process in order

Answer 81

anatomic diagnosis, differential diagnosis, etiologic diagnosis

ADE