Microbiology Chapters 16–18: Skin, CNS & Bloodstream Infections

What are the primary physical barriers of skin defenses?

Keratin and intact epidermis, which resist abrasion and water penetration.

What role do shedding skin cells play in skin defenses?

They remove attached microbes, reducing colonization.

How does sebum contribute to skin defenses?

It inhibits pathogens and supports protective microbiota.

What is the function of lysozyme in skin defenses?

It breaks down bacterial peptidoglycan, aiding in bacterial killing.

What is the significance of skin microbiota?

They compete with pathogens, produce inhibitory products, and can become opportunistic pathogens if the skin is damaged.

What is MRSA?

Methicillin-resistant Staphylococcus aureus, a Gram-positive cocci in clusters.

What are common symptoms of a Staphylococcus aureus infection?

Red, painful lesions, pus, warm skin, and fever.

What distinguishes Staphylococcus aureus from Streptococcus pyogenes?

S. aureus is catalase positive and coagulase positive, while S. pyogenes is catalase negative and beta hemolytic.

What is the hallmark of Impetigo?

Honey-colored crusts on the skin.

What is the primary agent of Staphylococcal Scalded Skin Syndrome (SSSS)?

Staphylococcus aureus, caused by exfoliative toxins.

What is the hallmark of Measles (Rubeola)?

Koplik spots and a rash that starts on the face and spreads downward.

What is the transmission method for Chickenpox?

Varicella-Zoster Virus (HHV-3) is transmitted through respiratory droplets.

What is the primary feature of Shingles?

A painful unilateral dermatome rash due to reactivation of latent VZV.

What are the main defenses of the eye?

Tears, lysozyme, lactoferrin, blinking, and mucus.

What is the hallmark of bacterial conjunctivitis?

Milky/purulent discharge.

What is the primary cause of neonatal conjunctivitis?

Neisseria gonorrhoeae and Chlamydia trachomatis.

What is Keratitis?

A corneal infection that can be caused by HSV-1 reactivation.

What is the definition of Meningitis?

Inflammation of the meninges.

What are classic symptoms of meningitis?

Fever, headache, and stiff neck, along with photophobia and nausea/vomiting.

What is the hallmark of Neisseria meningitidis?

Gram-negative diplococci with a petechial rash.

What is the primary risk factor for Listeria monocytogenes infection?

Consumption of unpasteurized dairy and lunch meats.

What is the disease caused by Naegleria fowleri?

Primary Amoebic Meningoencephalitis (PAM).

What is the hallmark of Creutzfeldt-Jakob Disease?

Dementia, memory loss, and muscle spasms caused by misfolded prion proteins.

What distinguishes Tetanus from Botulism?

Tetanus causes spastic paralysis while Botulism causes flaccid paralysis.

What is the transmission method for Rabies?

Animal bite leading to saliva transmission.

What is the hallmark of Chickenpox rash?

Vesicles in various stages starting from the scalp/face/trunk to extremities.

What is the main complication of Staphylococcal Scalded Skin Syndrome?

Widespread skin peeling (desquamation).

What type of bacteria is Streptococcus pyogenes?

Beta-hemolytic bacteria.

What is the hallmark symptom of impetigo?

Honey-colored crusts.

What condition is indicated by red streaks in the skin?

Cellulitis (lymphangitis).

What are Koplik spots associated with?

Measles.

What is the common name for fifth disease?

Slapped-cheek syndrome.

What follows a high fever in roseola?

A rash.

What is a characteristic rash of shingles?

Dermatome rash.

What does black eschar indicate?

Cutaneous anthrax.

What causes neonatal conjunctivitis?

N. gonorrhoeae or C. trachomatis.

What type of rash is associated with meningococcal meningitis?

Petechial rash.

What is a major risk factor for Listeria infection?

Consumption of unpasteurized dairy during pregnancy.

What type of virus is poliovirus?

Nonenveloped RNA virus.

How does Naegleria enter the human body?

Through the nose.

What does rabies post-exposure prophylaxis (PEP) consist of?

HRIG and vaccine.

What is the result of tetanus infection?

Spastic paralysis.

What is the effect of botulism on the body?

Flaccid paralysis.

What complication can arise from measles?

Subacute sclerosing panencephalitis (SSPE).

What is Cryptococcus associated with?

AIDS and pigeon droppings.

What is the most important organism causing neonatal meningitis?

Group B Streptococcus.

What is bacteremia?

Presence of bacteria in the blood.

What is septicemia?

Bacteria actively growing and multiplying in the blood.

What is sepsis?

Systemic inflammatory response to bloodstream infection leading to organ dysfunction.

What is septic shock?

Massive inflammatory response causing severe hypotension and poor tissue perfusion.

What is the vector for malaria?

Female Anopheles mosquito.

What is the human stage of the malaria life cycle?

Asexual reproduction.

What is a major complication of malaria caused by P. falciparum?

Cerebral malaria.

What is the gold standard for diagnosing malaria?

Blood smear.

What is the primary target cell for HIV?

Helper T (CD4) cells.

What defines AIDS?

CD4 < 200 cells/µL or the presence of an AIDS-defining illness.

What is the classic feature of brucellosis?

Undulant fever.

What is the hallmark symptom of cat-scratch disease?

Papules and lymph node enlargement after a cat scratch.