Eye & Skin Infections

Question 1

Viral conjunctivitis

Answer 1

• Redness in the eye

- May have some pus

Question 2

Bacterial conjunctivitis

Answer 2

Has more pus, compared to viral conjunctivitis

- Sometimes might glue eyelids shut

Question 3

Keratitis

Answer 3

Inflammation of the cornea

- Pus production: bacterial > viral

Question 4

Blepharitis

Answer 4

Inflammation of the lid margins due to infection or trauma

- mild

Question 5

Stye

Answer 5

Infected eyelid glands + follicles

• Extremely painful
• Cold/hot compress; Polysporin eyedrops containing antimicrobials

Question 6

What bacteria often infects the eyelids?

Answer 6

Staphylococcus aureus

Question 7

Acanthamoeba keratitis

Answer 7

Pus forms under the conjunctiva membrane

• Pus increases overtime
• May cause blindness
• Must use sterile cleaning solutions

Question 8

Conjunctiva

Answer 8

The thin layer of mucous membrane lining the eyelids + covering the surface of the eye.
- Very susceptible to infection because it creates a warm, moist environment ideal for microbial growth

Question 9

Mechanical barrier of eye

Answer 9

Eyelid

Question 10

Chemical barrier(s) of the eye

Answer 10

Tears with lysozyme + IgA

Question 11

What is the largest organ in the body?

Answer 11

Skin

Question 12

Normal flora on skin

Answer 12

1: Staphylococcus epidermidis (opp.)

• Diptheroids: Corynebacterium sp. (aerobic; surface); Propionibacterium sp. (anaerobic; follicles + glands)
• Some yeast
• Mostly Gram (+) microorganisms

Question 13

Mucous membrane

Answer 13

Sheets of epithelial cells attached to a basement membrane that lines body cavities.

• Has fairly acidic pH, which normal flora like to live in

Question 14

What are barriers to microbial growth on the skin?

Answer 14

Physical: dry, high salt, sebum
Chemical: Lysozyme, antimicrobial peptides

Question 15

Normal flora on conjunctival surface

Answer 15

• Micrococcus (ex. S. epidermidis)
• Alpha-hemolytic streptococci
• Diphtheroids (ex. Corynebacterium sp.)

Question 16

Chlamydia trachomatis

Answer 16

Serotypes A-C cause “trachoma”

• Usually found in tropical environments
• Transmitted by flies
• Leads to blindness
• Multiple infections causes functional blindness

Serotypes D-K, LGV cause “inclusion conjunctivitis”
- When eye is infected by genital chlamydia

Question 17

Opathalmia neonatorum

Answer 17

Gonorrhea in the newborn eye (Vertical T.)
- Can cause blindness + system infection (if spread to vascular sys. =death)
Prevention: antimicrobial drops

Question 18

Name the different type of skin lesions

Answer 18

Vesicle: <1 cm
Bulla: >1 cm
Macule: flat red rash, fairly small
Pustule (papule): deep in the skin; very painful

Question 19

Staphyloccocus sp.

Answer 19

• Gram (+) cocci in CLUSTERS
• Non-motile, non-spore forming, +/- capsules
• S. aureus, epidermidis, saphrophyticus

Question 20

Staphylococcus aureus

Answer 20

Gram (+) cocci

• Produces coagulase, which converts fibrinogen to fibrin
• Yellow/golden colonies in BAP
• Superbugs: MSSA or MRSA
• Virulence factors: Coagulase, Adhesion molecules, Membrane damaging toxins, Protein A, DNase, Capsule

Question 21

Impetigo

Answer 21

Infection of the epidermal layer

• Caused by staphylococci + streptococci
• Often in newborns + young children
• Treatment: remove crusts, washing lesions, apply topical ABs, oral ABs if infection spreads

Question 22

Toxic Shock Syndrome (TSS)

Answer 22

Caused by S. aureus (TSST-1 superantigen; #1) and S. pyogenes (GAS)

• Initially associated with tampon use, but nowadays is due to surgery + IV drug users
• Treatment: IV ABs (oxacillin, unless MRSA)

Question 23

Scaled Skin Syndrome (SSS)

Answer 23

• Neonatal or secondary to TSS
• Exofoliative toxin in S. aureus attacks epidermal cell junctions, causing skin to loosen
• Redness in skin
• Begins as skin lesions, then spreads
• Treatment: IV ABs

Question 24

Streptococcus sp.

Answer 24

• Gram (+) cocci in CHAINS

- Alpha, Beta, Gamma groups based on hemolytic reactions in BAP

Question 25

Streptococcus pyogenes (GAS)

Answer 25

- Group A streptococci (GAS) - Beta-hemolytic - Has M-protein in cell wall, which evades phagocytosis + attachment to target tissues - Causes pharyngitis, tonsillitus, impetigo, cellulitis, erysipelas, "childbed fever", necrotizing fasciitis - Post-infectious complications: Acute glomerulonephritis; Rheumatic fever - Toxins: Spe, Erythrogenic - Enzymes: Protease, Streptokinase, Deoxyribonucleases, Hyaluronidase

Question 26

Describe the toxins and enzymes associated with GAS.

Answer 26

- Spe toxin: massive tissue damage + inflammation (necro. faciitis); superantigen - Erythrogenic toxin: rash of Scarlet fever; superantigen - Protease: IgA - Deoxyribonucleases: DNA - Hyaluronidase: CT - Streptokinase: dissolves blood clots (fibrin)

Question 27

Erysipelas

Answer 27

Infection of dermal layer of skin - Can begin as pharyngitis and progress to septicemia + death - Treatment: ABs

Question 28

Streptococcal Impetigo

Answer 28

Infection of epidermal layer - Often in newborns + young children - Treatment: remove crusts, wash lesions, apply topical ABs or oral ABs if infection spreads

Question 29

Necrotizing faciitis (flesh eating disease)

Answer 29

- Caused by S. pyogenes - Transmitted by direct contact - Main symptom: disproportionate pain to injury - Bacteria invades deep and destroys fascia, liquifies tissue as it progresses - Rapidly progressive, require quick diagnosis and treatment (debridement of necrotic tissue, ABs) - Mortality >40%, even with timely treatment

Question 30

HPV

Answer 30

Human Papillomavirus | - Warts

Question 31

How many viruses in Herpesvirus group are human pathogens?

Answer 31

8 | - HSV-1 (cold sores) & HSV-2 (genital) are Herpes "simplex" virus

Question 32

HSV-1

Answer 32

- Mostly children infected - Transmitted via oral route or direct contact - Causes cold sores - Remains latent in trigeminal n. ganglia, and flares up w/ stress

Question 33

Herpes gladitorium

Answer 33

- Transmitted by direct contact - Found on the body - Common in wrestlers

Question 34

Herpes whitlow

Answer 34

- Occupational hazard of healthcare workers | - Accidental contact with cold sore of an infected patient

Question 35

Measles

Answer 35

Systemic disease characterized with maculopapular rash - Caused by rubeola virus - One serotype, no latent/persistence - Complications w/ secondary bacterial infections: S. aureus pneumonia + ear infections, Blindness in children w/ Vit. A deficiency, SSPE (type of encephalitis) - Symptoms: begin as respiratory, then progresses to fever, malaise, anorexia, conjunctivitis, photophobia, myalgia - Koplik's spots on buccal mucosa - Muculopapular rash starting from ears to legs - Tracheobronchitis + pneumonia are common - Causes immunosuppression - Vaccine: Live attenuated (need booster for non-responders); MMRV (current) with 2 doses (12-15 m., then 4-6 yrs)

Question 36

What symptoms are characteristic of measles?

Answer 36

Koplik's spots on buccal mucosa and Maculopapular rash (ears to legs)

Question 37

Canine distemper and rinderpest viruses are closely related to what virus?

Answer 37

Rubeola virus that causes measles.