Dermatological Conditions and Infectious Diseases

Acne

• Not contagious
• Causes: Overgrowth, overproduction of sebum stimulated by hormones
• Causative Agent: Propionibacterium acnes (normal flora in small amounts)
• Virulence Factor: Lipase
• Treatment: Cleansing; sometimes topical antibiotics

Boil

• Symptoms: Painful, purulent lesions
• Common for: MRSA (Methicillin-resistant Staphylococcus aureus)
• Causative Agent: Staphylococcus aureus
• Virulence Factors: Enzymes & toxins
• Diagnosis: Appearance & gram stain
• Treatment: Topical/oral antibiotics

MRSA

• Note: S. aureus gained methicillin resistance via plasmid
• Treatment: Use Vancomycin (VANC)

Impetigo

• Symptoms: Scabs that spread when picked
• Causative Agents: S. aureus or Streptococcus pyogenes (GAS)
• Virulence Factor: Exoenzymes that break down skin
• Diagnosis: Gram stain
• Treatment: Topical antibiotics

Abscess

• Symptoms: Purulence, swelling, often results from boil or cellulitis
• Causative Agents: S. aureus (including MRSA), GAS, VRE (vancomycin-resistant enterococci)
• Virulence Factors: Exoenzymes & toxins, PVL toxin, Hemolysin (VRE)
• Diagnosis: Gram stain (VRE cocci short)
• Treatment: Antibiotics + open & drain

Cellulitis

• Symptoms: Tight, hot, tender, painful, can exhibit lymphangitis (red streaks)
• Causative Agents: S. aureus, GAS, Pasteurella multocida, Bartonella henselae
• Virulence Factors: Deeper tissue enzymes & toxins
• Diagnosis: Gram stain
• Treatment: Antibiotics (oral or IV)

Staphylococcal Scalded Skin Syndrome (SSSS)

• Symptoms: Skin peeling, bullous lesions, primarily in babies
• Causative Agent: S. aureus
• Virulence Factors: Exfoliative toxins (ET-A, ET-B)
• Transmission: Spread by adults carrying S. aureus
• Treatment: Handwashing & antibiotics to prevent secondary infections

Scarlet Fever

• Symptoms: Strawberry tongue, Pastia lines (creases), rash absent around the mouth
• Causative Agent: GAS, begins as strep throat
• Virulence Factor: SpeA toxin
• Diagnosis: Culture/gram stain
• Treatment: Antibiotics

Chickenpox

• Symptoms: Macule-papule-vesicle-scab (POX), spread via aerosol or fluid
• Causative Agent: Varicella Zoster Virus (herpes virus)
• Virulence Factor: Latency
• Diagnosis: Appearance
• Treatment: Vaccine

Shingles

• Symptoms: Virus becomes latent in nerves, causes band-like lesions
• Causative Agent: Varicella Zoster Virus

Reye’s Syndrome

• Symptoms: Swelling in liver and brain, encephalopathy, confusion, seizures, hypoglycemia
• Cause: Viral infection combined with aspirin use

Fifth Disease

• Symptoms: Slap cheek, lacy rash, low fever
• Causative Agent: Parvovirus B19
• Note: Concern for pregnant mothers due to risk of transmission to fetus

Rubella

• Symptoms: Mild, macular rash, transmitted via respiratory or urine
• Causative Agent: Rubella virus
• Note: Teratogenic virus, transmitted in utero, covered by MMR vaccine

Measles

• Symptoms: Dry cough, conjunctivitis, Koplik’s spots, highly contagious
• Causative Agent: Measles Virus
• Virulence Factor: Syncytia formation
• Treatment: Symptom management, Vitamin A, MMR vaccine

Hand, Foot, and Mouth Disease

• Symptoms: Blister rash, potential nail loss
• Causative Agent: Coxsackievirus A16
• Virulence Factor: Viral

Warts

• Symptoms: Benign squamous epithelial growths, contagious
• Causative Agent: Human papillomavirus (HPV 1,2,3,4)
• Virulence Factor: Unregulated cell growth

Molluscum Contagiosum

• Symptoms: Pearly, plug-like lesions, can spread into clusters
• Causative Agent: Molluscum contagiosum virus (poxvirus family)

Ringworm (Cutaneous Mycoses)

• Symptoms: Scaly patches, circular lesions
• Causative Agents: Dermatophytes (multiple fungi)
• Diagnosis: Appearance or KOH test
• Treatment: Topical antifungals, hygiene

Tinea Versicolor

• Symptoms: Discolored patches
• Causative Agent: Malassezia furfur (fungal)
• Diagnosis: KOH test
• Treatment: Topical antifungals

Leishmaniasis

• Symptoms: Cutaneous, mucocutaneous, or systemic forms
• Causative Agent: Leishmania spp.
• Transmission: Spread by sand flies
• Diagnosis: Culturing for parasite
• Treatment: Antiparasitics

Gas Gangrene

• Symptoms: Tissue necrosis, anaerobic environment, "crunchy" texture
• Causative Agent: Clostridium perfringens
• Diagnosis: Smell, appearance, gram stain
• Treatment: Aggressive antibiotics & hyperbaric oxygen therapy

Anthrax

• Symptoms: Black eschar lesions, can be systemic
• Causative Agent: Bacillus anthracis
• Virulence Factors: Glutamate capsule, 3-part toxin
• Treatment: Immediate antibiotics

Styes

• Symptoms: Painful inflammation in sebaceous/lacrimal glands
• Causative Agent: S. aureus
• Treatment: Antibiotics, possible drainage

Conjunctivitis (Pink-eye)

• Symptoms: Discharge, bloodshot eyes
• Causative Agents: S. aureus, GAS, N. gonorrhoeae, Chlamydia
• Diagnosis: Appearance & discharge type
• Treatment: Varies based on type

Keratitis

• Symptoms: Gritty eye feeling, pain & light sensitivity
• Causative Agent: Herpes simplex virus (type 1)
• Treatment: Corticosteroids + antivirals

Trachoma

• Symptoms: Scarring, potential blindness
• Causative Agent: Chlamydia trachomatis (type A,B,C)
• Treatment: Antibiotics

Meningitis Overview

• Symptoms: Headache, stiff neck, increased WBC in CSF
• Diagnosis: Lumbar puncture for CSF
• Treatment: 3rd gen cephalosporins, steroids

Neisseria Meningitidis

• Symptoms: Sudden fever, flu-like symptoms
• Virulence Factors: Pili, capsule, LPS
• Most Dangerous: Type B, not covered by Menactra MCV4

Streptococcus pneumoniae

• Symptoms: Community-acquired pneumonia, otitis media
• Virulence Factor: Capsule
• Vaccine: Prevnar/Pneumovax

Haemophilus Influenzae

• Symptoms: Ear infections, sinusitis
• Virulence Factor: Capsule
• Vaccine: HiB

Listeria monocytogenes

• Symptoms: Foodborne, can affect elderly, infants
• Virulence Factors: Invasion, motility

Cryptococcus neoformans

• Symptoms: Gradual onset, respiratory symptoms, rash
• Diagnosis: Capsule stain on India ink

Coccidioides Immitis

• Symptoms: Pulmonary infection, potential 2ndary meningitis

Viral Meningitis

• Common in Children: Often caused by enteroviruses

Naegleria fowleri

• Symptoms: Meningoencephalitis, headache, fever, death
• Cause: Amoeba in warm water

Encephalitis Overview

• Symptoms: Behavior changes, vision loss, confusion
• Treatment: Aggressive antivirals, symptom management

Arbovirus Family

• Transmission: Insects, mosquitoes
• Common Variants: WNV, SLE, LaCrosse, Jamestown Canyon, Powassan, WEE/EEE

Other Viral Families

• Includes: Herpesvirus
• Treatment: Acyclovir

Rabies

• Symptoms: Progressive, zoonotic, fatal
• Forms: Furious and Dumb
• Treatment: Immediate antibodies and vaccine

Prion Diseases

• Characteristics: Converts normal proteins, leads to spongiform encephalopathies
• Examples: BSE, Creutzfeldt-Jakob disease, Kuru

Tetanus

• Symptoms: Lockjaw, rigid paralysis
• Causative Agent: Clostridium tetani
• Treatment: Antitoxin, VACCINE (DaPT)

Botulism

• Symptoms: Flaccid paralysis, respiratory compromise
• Causative Agent: Clostridium botulinum
• Treatment: Antitoxin

Urinary Tract Infections

• Bacterial VF: Urease, flagella, pili
• Diagnosis: Urinalysis, colony counts
• Types: E.coli UTI, Proteus species UTI, Staphylococcus saprophyticus UTI

Vaginitis and Vaginosis

• Symptoms: Itching, discharge
• Causative Agents: Candida albicans, Gardnerella vaginalis, Trichomonas vaginalis
• Diagnosis: KOH test for fungal
• Treatment: Antifungals, antibiotics

Prostatitis

• Symptoms: Pain, frequent urination
• Treatment: Broad-spectrum antibiotics

Sexually Transmitted Infections

• Include: Gonorrhea, NGU-2, Chlamydia, Syphilis, Herpes, HPV
• Diagnosis and Treatment: Varies by organism

General Notes on Treatment

• Antibiotics and Antivirals: Use specific, based on pathogen
• Resistance Issues: MRSA and VRE, use of last-line drugs
• Vaccines: Important prevention tool
• Hygiene Practices: Essential for prevention

Summary

This lecture covers a wide array of dermatological conditions and infectious diseases, detailing their symptoms, causative agents, virulence factors, diagnosis methods, and treatment options. Understanding these concepts is crucial for identifying and managing these health issues effectively.