Bacterial Skin Diseases Overview

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Questions and Answers

What is a common initial symptom of MRSA infections?

Persistent dry cough

Small red bumps (correct)

Nausea and vomiting

Fever and chills

Which patient demographic is most commonly associated with hospital-acquired MRSA (HA-MRSA)?

Elderly and immunosuppressed patients (correct)

Children in daycare centers

Young, healthy athletes

Travelers returning from tropical regions

What distinguishes CA-MRSA from HA-MRSA?

Easier to treat than HA-MRSA

Exclusively found in long-term care facilities

Usually occurs in healthy individuals (correct)

Only affects children

What is a common treatment method for MRSA abscesses?

Draining and debriding abscesses Signup and view all the answers

What is the primary concern with Vancomycin-resistant MRSA, also known as Super-MRSA?

It poses significant treatment challenges Signup and view all the answers

What is the most common organism isolated from gas gangrene infections?

Clostridium perfringens Signup and view all the answers

Which of the following is NOT a symptom of gas gangrene?

Severe itching at the infection site Signup and view all the answers

What is the primary treatment for gas gangrene?

Surgical removal of dead tissue Signup and view all the answers

What portal of entry is associated with gas gangrene infections?

Introduction into dead (necrotic) tissue Signup and view all the answers

Which of the following factors increases susceptibility to gas gangrene?

Deep, lacerating wounds Signup and view all the answers

What is the primary cause of smallpox?

Orthopoxvirus Signup and view all the answers

How do the lesions of smallpox differ from those of chickenpox?

Smallpox lesions develop at once and look alike on any one part of the body. Signup and view all the answers

What was the recommended method for the prevention of smallpox?

Immediate vaccination Signup and view all the answers

What is a significant difference in the incubation period between smallpox and chickenpox?

Smallpox has a longer incubation period than chickenpox. Signup and view all the answers

Which of the following is not a poxvirus that causes human diseases?

Chickenpox Signup and view all the answers

What is the incubation period for chickenpox?

2 to 3 weeks Signup and view all the answers

Which of the following diseases is caused by the varicellovirus?

Chickenpox Signup and view all the answers

What is a common treatment for shingles?

Acyclovir Signup and view all the answers

What can trigger the recurrence of herpes lesions?

Stress Signup and view all the answers

In which stage of progression does smallpox reach the pustular stage?

9 days after onset of fever Signup and view all the answers

What should not be given to children with chickenpox to avoid Reye's syndrome?

Aspirin Signup and view all the answers

What is a characteristic symptom of herpes infections?

Slowly spreading skin lesions Signup and view all the answers

What is the primary portal of entry for the varicellovirus?

Respiratory tract Signup and view all the answers

What is the primary method of transmission for HHV-2?

Sexual contact Signup and view all the answers

What type of bacteria predominantly makes up the normal microbiota of the skin?

Gram-positive aerobic cocci Signup and view all the answers

Which method is NOT typically used for wart removal?

Oral antibiotics Signup and view all the answers

Which disease is NOT caused by Staphylococcus aureus?

Necrotizing Fasciitis Signup and view all the answers

What is a characteristic of normal skin microbiota?

They can become opportunistic pathogens. Signup and view all the answers

What percentage of children are typically asymptomatic carriers of HHV-1 by age 2?

80% Signup and view all the answers

How can HPV typically lead to cervical cancer?

By activating oncogenes Signup and view all the answers

Which condition is associated with the infection caused by Staphylococcus aureus?

Carbuncles Signup and view all the answers

Which technique is used to diagnose warts?

Direct observation Signup and view all the answers

What is the main consequence of MRSA infections?

They are resistant to many antibiotics. Signup and view all the answers

Which of the following bacterial diseases is categorized as life-threatening?

Necrotizing Fasciitis Signup and view all the answers

What signifies that a treatment for HSV-1 or HSV-2 is effective?

Control of symptoms Signup and view all the answers

Which area is NOT commonly affected by warts?

Internal organs Signup and view all the answers

What role does Malassezia play in the context of skin health?

It is a yeast found in the skin's normal microbiota. Signup and view all the answers

What was the notable achievement of Harald zur Hausen in relation to HPV?

Winning the Nobel Prize in Medicine Signup and view all the answers

Which of the following is a common consequence of skin bacterial infections?

Bacteremia. Signup and view all the answers

Study Notes

Normal Microbiota of the Skin

Skin microbes are typically harmless
They include Gram-positive aerobic cocci (Staphylococcus and Micrococcus), Gram-positive anaerobic bacilli (diphtheroids), and yeast (Malassezia)
These microbes cannot be fully removed by normal cleaning
Under specific conditions, skin microbes can become opportunistic pathogens

Bacterial Diseases of the Skin

Skin infections can range from mild to severe
Examples include folliculitis, staphylococcal scalded skin syndrome (SSSS), MRSA infections, necrotizing fasciitis, acne and gas gangrene.

Diseases Caused by S. aureus

Folliculitis, styes, carbuncles, scalded skin syndrome, impetigo, toxic shock syndrome, bacteremia, food poisoning, pneumonia.

Staphylococcal Virulence Factors

Enzymes: coagulase, lipase, β-lactamase (break down molecules to enhance bacterial growth and survival)
Phagocytic factors: slime layer, protein A (hinder immune response)
Toxins: cytolytic toxins (damage cells), leukocidin (damage leukocytes), TSS toxin (triggers symptoms)

Folliculitis

Infection of a hair follicle, commonly caused by Staphylococcus species
Manifests as a red, swollen bump on the skin, also sometimes in the eyelid (sty), with further spread potentially causing furuncles (boils) or carbuncles.
Characterized by infection directly within the hair follicle-facultatively anaerobic, salt tolerant, desiccation tolerant.
Folliculitis cases most often resolved when individuals clean their skin.

Staphylococcal Scalded Skin Syndrome (SSSS)

Skin layers separate due to exfoliative toxins produced by some strains of Staphylococcus aureus.
Characterized by skin peeling in sheets
Primarily affects infants and immunocompromised individuals.

Methicillin-resistant S. aureus (MRSA)

Resistant to methicillin and many other types of antibiotics.
Infections may manifest as small red bumps (folliculitis), progressing to deep, painful abscesses
Common in hospitalized patients and individuals in healthcare settings.
Abscess may lead to bone or organ penetration.
Treatment often involves draining abscesses and using antibiotics like vancomycin, with resistant forms increasingly common, known as Super-MRSA.

Necrotizing Fasciitis

Severe infection of connective tissue beneath the skin, often due to Streptococcus pyogenes (Group A Streptococcus).
Pain, swelling, and rapid tissue destruction are prominent symptoms.
Often initially misdiagnosed due to non-specific symptoms
Treated aggressively with surgical removal of infected tissue and use of antibiotics (including clindamycin and penicillin).

Acne

Caused mostly by Propionibacterium acnes, an organism typically found in sebaceous glands.
More common during adolescence, some affected later on.
Diagnosed by visual inspection of the skin
Treatment varies by severity, often including antimicrobial drugs, topical treatments, drugs that cause exfoliation, retinoic acid (like Accutane), and/or blue light exposure to destroy P. acnes.

Cat Scratch Fever

Infection from Bartonella henselae, a Gram-negative bacterium
Often transmitted through cat scratches or bites
Initial symptoms include localized swelling, red papules
May affect organs like optic nerves too.

Pseudomonas Infection

Caused by Pseudomonas aeruginosa, a Gram-negative bacterium
Often opportunistic, infecting compromised individuals
Identified by characteristics like green discoloration (due to pigment pyocyanin)
Treatment challenging due to antibiotic resistance.

Gas Gangrene

Caused by Clostridium species (anaerobic, Gram-positive bacilli that form endospores.)
Introduced into necrotic tissue via injury.
Characterized by rapid tissue destruction, often associated with traumatic wounds.
Incubation period 1-3 days.
Treatment: surgical removal of dead tissue and antibiotic therapy.

Smallpox vs Chickenpox

Distinguishing features in the appearance and progression of lesions
Different causative viruses (orthopoxvirus and varicellovirus)
Smallpox eradicated due to a highly effective vaccination program; chickenpox vaccine available.

Herpes Infections

Caused by various herpes viruses, either through break in skin or mucous membrane
Lesions that may recur due to ongoing viral infection within nerves
Treatment focused on relief of symptoms (such as antiviral medications)
Prevention challenging due to the frequent reactivation of latent form.

Warts

Benign growths caused by human papillomaviruses (HPVs).
Can develop on many parts of the body.
Typically transmitted by direct contact, but may persist even after initial resolution.

History of Coronaviruses

Several coronaviruses have caused various diseases, some mild (common cold), others serious like SARS, MERS, and COVID-19.
SARS-CoV-1 originated in Asia, MERS in Saudi Arabia.
COVID-19 originated in Wuhan, China
Variants of concern, like Delta and Omicron, have emerged and are prevalent.

COVID-19 Pathogenesis

Virus enters via ACE-2 receptors, mainly targeting lung tissues
Replication triggers inflammation response (cytokine storm)
Leading to severe symptoms of respiratory distress, blood clotting events, kidney, liver and other organ dysfunction
Some individuals have long-term complications (long COVID).

COVID-19 Diagnosis, Treatment and Prevention

Diagnosed with RT-PCR or Antigen tests
Treatment includes supportive care, antiviral medications, and sometimes experimental therapies
Prevention strategies include vaccines, hygiene, social distancing.

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Description

This quiz covers key concepts related to the normal microbiota of the skin, various bacterial diseases, particularly those caused by Staphylococcus aureus, and their virulence factors. Understand the balance between harmless skin microbes and those that can become opportunistic pathogens. Test your knowledge on symptoms, infections, and the impact of bacteria on skin health.