Diseases of Skin and Eyes

Antibiotics

• Broad/Narrow spectrum: Ex. Penicillin affects G+ but very few G-

• Action and families:– Penicillins: (amoxicillin) inhibit cell wall synthesis

• Some org. become resistant-produce penicillinase (β-lactamase)• HW: Augmentin?

– Cephalosporins: (cephalothin) inhibit cell wall synthesis• Resistant to penicillinases and effective against more G-

– Bacitracin: (Bacillus isolated from girl named Tracy) topical, effective primarily against staph. and strep.

– Increase in cases with penicillin resistant S. aureus

Date: 7 Feb 2003 Promed

A 10 year old previously well African-American boy was seen recently by our facility after suffering a fall 2 days earlier. He complained of fever, nausea, vomiting, and diarrhea for 2 days, had some right hip pain and was tachycardic. A chest and affected hip radiograph were unremarkable, and he was discharged with diagnoses of hip contusion and viral gastroenteritis. Two days later, he was seen again with the same symptoms as well as back and leg pains. A chest radiograph now showed large left lower lobe and small right upper pulmonary infiltrates. Over several hours, despite cefuroxime, ampicillin, and azithromycin, he developed multisystem failure and died.

A blood culture grew a methicillin resistant _Staphylococcus aureus_ (MRSA) that was sensitive to clindamycin, ciprofloxacin, trimethoprim-sulfamethoxazole, aminoglycosides, and vancomycin. Epidemiologically, this case was felt to represent a fatal septicemic episode of community acquired MRSA necrotizing pneumonia (confirmed on postmortem examination). The isolate is being examined for similarity to other community acquired MRSA strains.

Sheldon Landesman MDDirector, Infectious DiseasesBrookdale Medical CenterBrooklyn, New York

– Aminoglycosides: (Streptomycin, Neomycin, Gentamicin)

• inhibit protein synthesis, changes shape of 30s portion of ribosome

• broad spectrum, one of first discovered to have significant activity against G-

– Tetracyclines: (Terramycin, Tetracycline, Minocycline)

• Inhibit protein synthesis, prevent t-RNA from binding to mRNA, ribosomal complex

• Effective against both G+ and G-

– Macrolides: (Erythromycin) • inhibit protein synthesis, binds 50s portion of ribosome so

can’t move along mRNA• can’t penetrate G- cell wall, used for G+

– Quinolones and Fluoroquinolones: (Ciprofloxacin)• inhibit nucleic acid synthesis, inhibits DNA gyrase• Broad spectrum, not given to children, adolescents or pregnant

women because affect development of cartilage

– Sulfonamides: (combination of trimethoprim and sulfamethoxazole)

• inhibit synthesis of essential metabolites, similarity to PABA, a chemical necessary to make folic acid

• Example of synergism– When used in combination, only small percentage needed of

each drug compared to one drug alone– Combinations usually have broader spectrums– Reduces emergence of resistant strains

Bacterial Diseases

• Impetigo: most common skin infection in children– Signs and symptoms: local infections, characterized by

isolated pustules that become crusted and rupture– Transmission: mostly through contact, bacteria

penetrate skin through minor abrasion or insect bite– Causative agent: Strep. or Staph.– Rx: Topical antibiotic-Bactroban, Systemic

antibiotics-Cephalexin, Erythromycin– Source: www.nlm.nih.gov (medlineplus)

• Folliculitis: infection of hair follicle– Signs and symptoms: rash, pimples

surrounding hair follicule, itching, reddened skin area

– Transmission: result of injury or damage to hair follicle

– Causative agent: Staph.– Rx: Topical antibiotic-Bactroban, Systemic-

dicloxacillin or antifungal rx if necessary– Source: www.nlm.nih.gov (medlineplus)

• Toxic Shock Syndrome:

• severe disease caused by a toxin made by Staphylococcus aureus, characterized by shock and multiple organ dysfunction. – Signs and Symptoms:High fever, sometimes accompanied by

chills • Profound malaise • Nausea, vomiting and/or diarrhea • Diffuse red rash resembling a sunburn • Rash followed in 1 or 2 weeks by peeling of the skin, particularly the

skin of the palms or soles • Redness of eyes, mouth, throat • Confusion, seizures, headaches • Myalgias (muscle aches) • Hypotension (low blood pressure) (This is a sign of what?)• Organ failure (usually kidneys and liver)

• Causative agent: toxin produced by S.areus– TSST-1: superantigen (toxemia)– Risk factors include recent menstruation, recent use of barrier

contraceptives such as diaphragms and vaginal sponges, vaginal tampon use (especially prolonged), recent childbirth, recent surgery, and current S. aureus infection.

– Has declined in recent years since removal of super-absorbent tampons were taken off the market.

• Rx: intravenous fluids, blood pressure support, and dialysis (if severe kidney dysfunction is present). Antibiotic therapy is also used and in some cases, intravenous immunoglobulin may be required

– May be fatal in up to 50% of cases

– Source: www.nlm.nih.gov (medlineplus)

• TSLS: Toxic Shock Like Syndrome– Very similar to TSS

• Has become more prevalent now that TSS has decreased.

– Symptoms: same as TSS• Same symptoms as G- septic shock, except rash present

– Causative agent: S. pyogenes• SpeA, SpeB, SpeC (main toxin is SpeA)

• Superantigen

– RX: Same as TSS

• Possible connection between Scarlet Fever (caused by S. pyogenes), TSS, and TSLS

• Childhood disease. Famous case in 1800’s– Begins as pharingitis, organism begins to

produce toxin– Symptoms: pinkish-red rash, covers whole

body except palms and soles• Body’s reactions to circulating toxin• Tongue has spotted, strawberrylike appearance and

then loses upper membrane• Tongue becomes very red and enlarged• Affected skin frequently peels off

• Transmission: Inhalation of infective droplets– Decreased in frequency since use of Penicillin – Varies in severity and frequency with location– Now seeing connection with streptococcal skin

infections– Decrease in Scarlet fever, resulted in discovery

of TSS and later TSLS– Similar toxin? Same toxin?

• Necrotizing Fasciitis: severe type of tissue infection that can involve the skin, subcutaneous fat, the muscle sheath (fascia), and the muscle. It causes gangrenous changes, tissue death, systemic

disease, and frequently death – Signs and Symptoms:

• Severe pain in the area • swelling in the area • Discoloration in the area • May appear reddened, bronzed, bruised, or purple (purpuric) • Progresses to dusky, dark color

• Bleeding into the skin • Visible dead (necrotic) tissue • Skin color, patchy • Skin breaks (open wound) • Skin around the wound feels hot and looks reddened, raised, or discolored

(inflamed) • Oozing fluid ranging from yellowish clear or yellowish bloody to puslike

in quality • fever • General ill feeling (malaise)

• Causative Agent: Streptococcus (can also be caused by Mycobacterium ulcerans)

• Prevention: Clean any skin injury thoroughly. Watch for signs of infection such as redness, pain, drainage, swelling around the wound, and consult the health care provider promptly if these occur.

• Rx: Powerful broad-spectrum antibiotics must be administered immediately. They are given intravenously (in a vein) to attain high blood levels of the antibiotic in an attempt to control the infection. Surgery is required to open and drain infected areas and remove (debride) dead tissue. Skin grafts may be required after the infection is cleared. If the infection is in a limb and cannot be contained or controlled, amputation of the limb may be considered. Sometimes pooled immunoglobulins (antibodies) are given by vein to help fight the infection.

• Fatalities are high

• Source: www.nlm.nih.gov (medlineplus)

• Erysipelas: a type of (cellulitis) skin infection– Signs and Symptoms:

• An erysipelas skin lesion typically has a raised border that is sharply demarcated from normal skin. The underlying skin is painful, intensely red, hardened (indurated), swollen, and warm.

• Facial erysipelas classically involve the cheeks and the bridge of the nose.

• Blisters may develop over the skin lesion.

• Fever and shaking chills are common

– Causative Agent: Strep.

• Prevention: Avoiding cuts and scrapes may reduce the risk for the development of erysipelas

• Rx: The cornerstone of therapy is treatment with antibiotics such as penicillin, which are active against streptococci. – Depending on the severity, intravenous antibiotics may

be used. In less severe cases, oral antibiotics may be sufficient.

– In individuals who have recurrent erysipelas, long-term antibiotics may be required.

• Source: www.nlm.nih.gov (medlineplus)

Diseases of Eyes

• Bacterial– Neonatal Gonorrheal Opthalmia: serious form of

conjunctivitis• Symptoms: Acute infection with much pus formation

– At more advanced stages ulcers form on cornea

– infection carries high risk of blindness

• Causative Agent: Neisseria gonorrhoeae

• Transmission: acquired as infant passes through the birth canal

• Rx: oral Tetracycline or Erythromycin drops for prevention

– Inclusion Conjunctivitis: • Symptoms: swelling of eyelid, mucus and pus

formation

• Causative Agent: Chlamydia trachomatis

• Transmission: acquired in birth canal or in unchlorinated swimming pools

• Rx: Tetracycline ointment

– Trachoma: eye infection which may result in chronic scarring

and blindness if left untreated. (Also known as “pink eye”) • Symptoms: conjunctivitis

– discharge from the eye

– swollen eyelids

– turned-in eyelashes

– swelling of lymph nodes just in front of the ears

– Cloudy cornea

• Causative Agent: Chlamydia trachomatis

• Transmission: acquired via direct contact with eye or nose-throat secretions from affected individuals or by contact with inanimate objects which are contaminated with these secretions, such as towels or clothes. In addition, certain flies which have fed on these secretions can transmit trachoma

• Rx: Erythromycin, Tetracycline

• Viral Disease of Eye– Herpetic Keratitis: Herpes simplex keratitis is a

serious viral infection. It may have recurrences that are triggered by stress, exposure to sunlight, or any condition, disease or treatment which impairs the immune system.

– Symptoms: eye pain – Impaired vision – Eye redness – White patch on the cornea – Sensitivity to light – Increased tearing

• Causative Agent: Herpes simplex 1 (cold sores)• Transmission: problem for contact lens wearers especially• Rx: Trifluridine may be effective

– Protozoan Disease• Acanthameoba keratitis: frequently results in severe

eye damage– Symptoms: eye pain

• Impaired vision

• Eye redness

• White patch on the cornea

• Sensitivity to light

• Increased tearing

– Transmission: contact lenses

– Rx: Topical ointment (propamidine or miconazole), corneal transplant or eye removal may be required