Pathology and Infectious Disease Overview

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Questions and Answers

Which of the following statements accurately describes the concept of disease?

The invasion of pathogens in the body

A mild illness that resolves spontaneously

A temporary state of health

An abnormal state where normal body functions are disrupted (correct)

What is the first criterion of Koch's postulates?

The pathogen must be isolated from the environment

The pathogen must be invisible under a microscope

The pathogen should be present in every instance of the disease (correct)

The pathogen must be extracted from a healthy host

How are communicable diseases best defined?

Diseases that are caused by genetic factors

Diseases that can be transmitted only via direct contact

Diseases unable to be transferred between hosts

Diseases that can be spread from one host to another (correct)

What structure of the skin is primarily responsible for waterproofing?

Keratin Signup and view all the answers

What type of diseases are characterized by specific groups of signs and symptoms?

Syndrome Signup and view all the answers

What is the main characteristic of nonbullous impetigo?

It involves crusting sores that can spread by autoinoculation. Signup and view all the answers

Which of the following correctly characterizes a contagious disease?

A communicable disease that spreads easily and rapidly Signup and view all the answers

Which condition is associated with a blistering form of impetigo?

Scalded skin syndrome Signup and view all the answers

Which of the following components is NOT part of the normal microbiota of the skin?

Pathogenic bacteria Signup and view all the answers

What are the common symptoms of Toxic Shock Syndrome (TSS)?

Fever, vomiting, shock, and organ failure Signup and view all the answers

What is a primary virulence factor produced by Group A streptococci?

M proteins Signup and view all the answers

Which of the following best describes the structure of the epidermis?

Thin outer portion composed of epithelial cells Signup and view all the answers

Which disease is characterized by deep skin infection due to skin breaks?

Cellulitis Signup and view all the answers

What is the characteristic feature of erysipelas caused by Streptococcus pyogenes?

Infection of the dermal layer of the skin Signup and view all the answers

What is the most common cause of necrotizing fasciitis?

Streptococcus pyogenes Signup and view all the answers

Which statement about Streptococcus pyogenes is false?

It produces only endotoxins. Signup and view all the answers

What is the defining characteristic of bullae?

Vesicles larger than 1 cm in diameter Signup and view all the answers

Which bacterium is known for being antibiotic-resistant and often associated with severe skin infections?

Staphylococcus aureus Signup and view all the answers

Which of the following describes a furuncle?

Localized region of pus surrounded by inflamed tissue Signup and view all the answers

What percentage of normal skin microbiota is Staphylococcus epidermidis estimated to represent?

90% Signup and view all the answers

What is the primary transmission method for MRSA infections?

Direct contact with an infected wound or contaminated surfaces Signup and view all the answers

Which skin condition is characterized as folliculitis of an eyelash?

Sty Signup and view all the answers

Which of the following is NOT a skin abnormality mentioned?

Cysts Signup and view all the answers

What type of bacteria are Staphylococci classified as?

Gram-positive cocci in clusters Signup and view all the answers

What is the primary transmission method for Pseudomonas dermatitis?

Acquired in swimming pools Signup and view all the answers

What is a key characteristic of Mycobacterium ulcerans?

It produces the toxin mycolactone Signup and view all the answers

What type of acne is primarily caused by the digestion of sebum by Propionibacterium acnes?

Inflammatory acne Signup and view all the answers

Which condition is characterized by deep and damaging ulcers that may require amputation?

Buruli Ulcer Signup and view all the answers

Which of the following skin diseases is NOT primarily caused by a bacterium?

Smallpox Signup and view all the answers

What treatment is common for combating Propionibacterium acnes?

Antibiotics and benzoyl peroxide Signup and view all the answers

What is a prominent symptom of Otitis externa, caused by Pseudomonas aeruginosa?

Ear pain and inflammation Signup and view all the answers

Which of the following skin diseases primarily affects children and developing fetuses?

Chickenpox Signup and view all the answers

Study Notes

Pathology, Infection, and Disease

Pathology: The study of disease
Infection: The invasion of the body by pathogens
Disease: When the body is not functioning normally due to an abnormal state.

Koch's Postulates

Koch's postulates are used to prove that a specific pathogen causes a specific disease.
The same pathogen must be present in every case of the disease.
The pathogen must be isolated from the diseased host and grown in a pure culture.
The pathogen from the culture must cause the disease when inoculated into a healthy lab animal.
The pathogen must be isolated from the inoculated animal and must be the original species.

Infectious Disease Classification

Symptoms: Changes in bodily functions that patients experience, e.g., fatigue, nausea. Measurable changes in the body.
Signs: Changes in the body that can be measured or observed, e.g., fever, changes in white blood cell count.
Syndrome: A specific collection of signs and symptoms that are frequently associated with a disease.
Communicable disease: A disease spread from one host to another.
Contagious disease: A communicable disease that spreads easily and rapidly.
Noncommunicable disease: A disease that is not spread from one host to another.

Skin Structure and Microbiota

Epidermis: The thin, outermost layer of skin, composed of epithelial cells.
Keratin: A protein that provides a waterproof barrier to the outer layer of the epidermis (also found in hair and nails) .
Dermis: The thick layer of skin beneath the epidermis, primarily composed of connective tissue.
Normal skin microbiota: Includes gram-positive cocci (like staphylococci) and some yeasts. They are resistant to drying and high salt concentrations, often colonizing hair follicles or skin surfaces.

Microbial Skin Diseases - Characteristics

Vesicles: Small fluid-filled lesions.
Bullae: Vesicles larger than 1 cm in diameter.
Macules: Flat, reddened lesions.
Papules: Raised lesions.
Pustules: Raised lesions with pus.
Exanthem: A skin rash arising from a disease.

Bacterial Skin Diseases

Staphylococci: Gram-positive cocci in clusters; common skin bacteria. Includes Staphylococcus epidermidis and Staphylococcus aureus.
Streptococci: Gram-positive cocci in chains; a common cause of skin diseases and Streptococcus pyogenes.
Pseudomonas aeruginosa: Gram-negative, aerobic rod; opportunistic pathogen; can cause skin infections.
Mycobacterium ulcerans: Gram-positive; causes Buruli ulcer.
Propionibacterium acnes: Anaerobic microbe; common cause of acne.

Viral Skin Diseases

Warts: Caused by papillomaviruses; transmitted by contact.
Smallpox: Caused by Orthopoxvirus; eradicated thanks to vaccination.
Chickenpox: Caused by varicella-zoster virus; prevented by vaccine.
Shingles: Caused by varicella-zoster virus; reactivation of the latent virus; commonly in elderly, immunocompromised cases.
Herpes simplex: Caused by HSV-1 and HSV-2; transmitted via contact; causes cold sores and genital herpes.
Measles: Caused by rubella virus; transmitted via respiratory route; prevented by vaccine.
Rubella: Caused by rubella virus; transmitted via respiratory route; prevented by vaccine. (German measles)

Fungal Skin and Nail Diseases

Cutaneous mycoses: Superficial fungal infections of the skin and nails (caused by dermatophytes).
Athlete's foot: Fungal infection causing itchy rash.
Ringworm: Fungal infection causing circular rash.
Subcutaneous mycoses: More serious fungal infections that penetrate the stratum corneum (e.g., sporotrichosis).

Insect-Caused Diseases

Scabies: Caused by Sarcoptes scabiei mites; transmitted through close contact. Causes inflammatory skin lesions.
Pediculosis: Caused by lice (Pediculus humanus capitis - head lice and P.h. corporis - body lice)

Eye Diseases

Conjunctivitis: Inflammation of the conjunctiva, commonly caused by Haemophilus influenzae bacterium or in some cases viral or bacterial infections.
Ophthalmia Neonatorum: Transmission through birth canal (often due to untreated gonorrhea); inflammation of newborn eyes, potentially resulting in blindness.
Inclusion Conjunctivitis: Caused by Chlamydia trachomatis; transmitted through birth canal and can spread in swimming pools, in which case it's rare.
Trachoma: Caused by Chlamydia trachomatis; leading cause of blindness worldwide, transmitted through hand contact and flies.

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Description

This quiz explores the fundamentals of pathology, infection, and disease. It delves into Koch's postulates and the classification of infectious diseases based on symptoms and signs. Test your understanding of how pathogens affect the body and the criteria used to establish disease causation.