Chapter 10_2 flashcards

Question 1

Staphylococcal Infections: Causative Organism & Characteristics

Answer 1

Staphylococcus aureus (most virulent), S. epidermidis, S. saprophyticus. Gram-positive cocci (form clusters). [cite: 33] S. aureus colonizes skin, vagina, nares, oropharynx. [cite: 33] Secretes toxins and proteases. [cite: 33]

Question 2

Staphylococcal Infections: Common Diseases & Resistance

Answer 2

S. aureus causes: Skin/soft tissue infections (abscesses, boils, cellulitis, impetigo, folliculitis), osteomyelitis, respiratory infections, endocarditis (IV drug users), septicemia, staphylococcal food poisoning. Antibiotic resistance: MRSA (methicillin-resistant), VRSA (vancomycin-resistant). [cite: 33]

Question 3

Streptococcal Infections: General Characteristics

Answer 3

Gram-positive cocci, often in chains. Several strains cause human infections. [cite: 34]

Question 4

Group A Beta-Hemolytic Streptococcus (GABHS / S. pyogenes): Virulence & Diseases

Answer 4

Secretes virulence factors (streptolysin S/O, streptokinase, exotoxins) causing beta hemolysis. [cite: 36] Causes: Pharyngitis (strep throat), scarlet fever, rheumatic fever, glomerulonephritis, skin infections, pneumonia, necrotizing fasciitis, toxic shock syndrome, PANDAS. [cite: 35, 36]

Question 5

PANDAS (Pediatric Autoimmune Neuropsychiatric Disorder Associated with Streptococcus)

Answer 5

Obsessive-compulsive disorder or tics appearing shortly after GABHS infection in children. May include anxiety, irritability, sleep problems, motor difficulties. [Text]

Question 6

Pneumonia (Bacterial): Streptococcus pneumoniae (Pneumococcus)

Answer 6

Most common cause of community-acquired pneumonia (CAP). [cite: 37] Gram-positive diplococci. [cite: 37] Colonizes nasopharynx. Antibiotic resistance common. Pneumococcal vaccine available. [cite: 37] Symptoms: High fever, rigors, productive cough, pleuritic chest pain, dyspnea. [Text]

Question 7

Pneumonia (Bacterial): Mycoplasma pneumoniae

Answer 7

Small bacteria, lacks cell wall. [cite: 38] Causes “walking pneumonia,” common in school-aged children/young adults. [cite: 38] Symptoms: Mild fever, sore throat, chills, cough, myalgias, headache, earache. [Text] Treatment: Specific antibiotics (e.g., tetracyclines). [Text]

Question 8

Pneumonia (Bacterial): Legionnaire’s Disease (Legionella pneumophila)

Answer 8

Gram-negative bacteria found in warm, moist air conditioning systems of large buildings. [cite: 38] Transmitted via aerosol mist (not person-to-person). [cite: 38] Symptoms: Dyspnea, chest pain, nonproductive cough, hemoptysis, fever, GI symptoms, headache. [Text]

Question 9

Pseudomonas Infection: Pseudomonas aeruginosa

Answer 9

Gram-negative rod. [cite: 40] Common in patients hospitalized >1 week (health-care acquired). [cite: 40] Can infect many systems, may be life-threatening. [cite: 40] Frequent cause of ventilator-associated pneumonia (VAP). [cite: 40] Treatment: Double antibiotic therapy. [Text]

Question 10

Bacterial Meningitis: General Signs & Diagnosis

Answer 10

More severe than viral. Common signs: Fever, nuchal rigidity (stiff neck), headache, photophobia. [cite: 41] Kernig’s and Brudzinski’s signs positive. [cite: 41] Diagnosis: Lumbar puncture for CSF analysis (elevated protein/WBCs, low glucose, culture). [cite: 41]

Question 11

Bacterial Meningitis: Neisseria meningitidis (Meningococcus)

Answer 11

Gram-negative diplococcus. [cite: 42] Transmitted by droplet. [cite: 42] May occur as meningococcemia first (rash, petechiae, purpura, gangrene). [cite: 42] Vaccine available. [cite: 42] Outbreaks in close quarters (dorms, military). [Text]

Question 12

Bacterial Meningitis: Haemophilus influenzae (Hib)

Answer 12

Gram-negative coccobacillus, subtype b most virulent. [cite: 42] Children and elderly most at risk. [cite: 42] Childhood immunization (Hib vaccine) has reduced incidence. [cite: 42] Can cause bacteremia, meningitis, cellulitis, epiglottitis, septic arthritis, pneumonia. [Text]

Question 13

GI Bacterial Infection: Salmonella (S. enterica, S. typhi)

Answer 13

Gram-negative rods. S. enterica causes gastroenteritis (vomiting, diarrhea often bloody). [cite: 43] S. typhi causes typhoid fever (high fever, cough, abdominal pain, watery diarrhea, cardiac issues, rose spots rash). [cite: 43] Transmission: Contaminated food (poultry, eggs), water, animals. [cite: 44]

Question 14

GI Bacterial Infection: Shigella (Shigellosis)

Answer 14

Gram-negative rods. Causes severe, bloody diarrhea (dysentery). [cite: 44] Complications: Hemolytic-Uremic Syndrome (HUS). [cite: 44] Transmission: Fecal-oral, direct contact (e.g., diaper changes in child care). [Text]

Question 15

GI Bacterial Infection: Escherichia coli (E. coli)

Answer 15

Gram-negative rods, many strains. [cite: 46] E. coli O157:H7 (enterohemorrhagic - EHEC) causes severe gastroenteritis, bloody diarrhea, can lead to HUS. [cite: 46] Lives in cattle intestines; transmission via undercooked meat, contaminated produce/water. [cite: 46] Uropathogenic strains cause UTIs. [Text]

Question 16

GI Bacterial Infection: Campylobacter jejuni

Answer 16

Gram-negative, helical-shaped. Common cause of gastroenteritis (diarrheal, usually self-limiting). [cite: 46] Transmission: Contaminated food (esp. poultry), animal feces. Complication: Guillain-Barré syndrome (rare). [Text]

Question 17

GI Bacterial Infection: Cholera (Vibrio cholerae)

Answer 17

Toxin-producing, flagellated bacterium. Causes profuse, watery “rice water” diarrhea. [cite: 47] Leads to rapid dehydration, electrolyte imbalance. Transmission: Contaminated water/food (fecal-oral). [cite: 48] Vaccines available. Treatment: Fluid/electrolytes, doxycycline. [cite: 50, 51]

Question 18

Diphtheria: Organism, Toxin & Key Feature

Answer 18

Corynebacterium diphtheriae. [cite: 52] Bacteria secretes toxin producing a gray-colored pseudomembrane in throat/respiratory tract, can cause obstruction. [cite: 52] Vaccine: DTaP/Tdap. [cite: 52]

Question 19

Pertussis (Whooping Cough): Organism, Toxin & Key Feature

Answer 19

Bordetella pertussis. [cite: 55] Produces toxin affecting ciliary action of respiratory tract. [cite: 55] Characterized by episodes of spasmodic, forceful coughing with an audible whoop. [cite: 55] Vaccine: DTaP/Tdap. [cite: 52]

Question 20

Tetanus (Lockjaw): Organism, Toxin & Key Feature

Answer 20

Clostridium tetani (spore-forming anaerobe found in soil). [cite: 55] Produces toxin blocking inhibitory neurotransmitters -> hyperactivity of neurons, intense muscle spasms (lockjaw, opisthotonus). [cite: 55] Vaccine: DTaP/Tdap/Td. [cite: 52, 53]

Question 21

Botulism: Organism, Toxin & Key Feature

Answer 21

Clostridium botulinum (spore-producing, toxin-secreting, found in soil). [cite: 56] Toxin affects neurons, causing descending flaccid paralysis (cranial nerves first). [cite: 56] Sources: Improperly canned foods, contaminated water, honey (infants). [Text] “Botox” is therapeutic form. [cite: 57]

Question 22

Clostridium difficile (C. diff) Infection

Answer 22

Spore-forming, toxin-secreting anaerobic bacterium. [cite: 58] Prolonged antibiotic use distorts normal GI flora, enabling C. diff overgrowth. [cite: 58] Toxins disrupt intestinal mucosa, forming pseudomembranes. Symptoms: Prolonged, frequent diarrhea; fever; abdominal pain. [Text]

Question 23

Clostridial Gas Gangrene: Organism & Pathophysiology

Answer 23

Clostridium perfringens (most common). [cite: 58] Causes myonecrosis (rapidly spreading necrotizing infection of muscle/tissue). [cite: 58] Toxin causes vascular injury, necrosis, hemolysis. Spreads ~2cm/hr. Usually in wound post-trauma/surgery. 100% fatal if untreated. [Text]

Question 24

Lyme Disease: Organism, Vector & Key Rash

Answer 24

Borrelia burgdorferi (spirochete). [cite: 59] Transmitted by deer tick. [cite: 59] Characteristic rash: Erythema migrans (painless, red macule expanding to target-like lesion). [cite: 59] Later: arthritis, nerve involvement (Bell’s palsy). [Text]

Question 25

Rocky Mountain Spotted Fever (RMSF): Organism, Vector & Key Rash

Answer 25

*Rickettsia rickettsii* (small, gram-negative bacillus). [cite: 60] Transmitted by dog tick or wood tick. [cite: 60] Rash: Red, spotted petechial rash, often appears day 6+, may involve palms/soles. [cite: 60] Causes increased vascular permeability -> edema, hypotension. [Text]

Question 26

Viral Infection: Common Cold

Answer 26

Caused by Rhinovirus, Coronavirus, Adenovirus. [cite: 61] Transmission: Direct contact, droplet. Symptoms: Rhinorrhea, sneezing. Usually self-limiting (4-9 days). [Text]

Question 27

Viral Infection: Influenza

Answer 27

Influenza virus types A, B, C (A causes most severe outbreaks due to mutation). [cite: 61] Transmission: Droplet, aerosols. [cite: 63] Symptoms: Abrupt onset fever, chills, headache, myalgias, arthralgias, cough, sore throat. [cite: 61] Seasonal vaccine due to high mutation rate. [cite: 62]

Question 28

Viral Infection: SARS-CoV-2 (COVID-19)

Answer 28

RNA virus with surface spikes. [cite: 67] Transmission: Person-to-person via droplets, surfaces. [Text] Incubation ~10 days. Symptoms: Fever, rhinorrhea, dry cough, SOB, weakness, fatigue, myalgias, anosmia/ageusia. [cite: 67] Severe: Pneumonia, ARDS, sepsis, cytokine storm, DIC, microthrombi. [Text] Vaccines available. [Text]

Question 29

Viral Infection: Epstein-Barr Virus (EBV) / Mononucleosis

Answer 29

Causes infectious mononucleosis. [cite: 68] Spread by oral secretions (virus infects oropharynx epithelium, salivary glands, B lymphocytes). [Text] Symptoms: Pharyngitis (often most prominent), severe fatigue, lymphadenopathy (cervical common), splenomegaly, fever. [cite: 68] Diagnosis: Heterophile antibody test (Monospot less accurate). [Text]

Question 30

Viral Infection: Cytomegalovirus (CMV)

Answer 30

Can cause asymptomatic infection, birth defects (congenital CMV - microcephaly, jaundice, retinitis), mononucleosis-like syndrome in adults, severe disseminated infection in immunocompromised (pneumonitis, retinitis, hepatitis, encephalitis). [cite: 68] Remains dormant post-infection. [Text]

Question 31

Viral Infection: Measles (Rubeola)

Answer 31

RNA virus. Highly contagious (respiratory droplets, airborne up to 2h). [Text] Symptoms: High fever, cough, URI, conjunctivitis, photophobia. [cite: 69] Pathognomonic: Koplik's spots in oral mucosa. [cite: 69] Maculopapular rash (head to toe). Leading cause of death in children worldwide. Prevention: MMR vaccine. [cite: 69]

Question 32

Viral Infection: Mumps

Answer 32

Paramyxovirus, droplet transmission. [cite: 69] Symptoms: Parotitis (swollen parotid gland - "gopher-like"), fever, sore throat. [cite: 69] Complications: Encephalitis, Orchitis (can result in sterility in males). [Text] Prevention: MMR vaccine. [cite: 69]

Question 33

Viral Infection: Rubella (German Measles)

Answer 33

RNA virus (Rubivirus), droplet transmission. [cite: 69] Symptoms: Rash (discrete red macules, face to extremities), fever, sore throat, rhinitis. Forchheimer’s spots (soft palate). Hallmark: Generalized tender lymphadenopathy. [Text] Major complication: Congenital Rubella Syndrome (CRS) if pregnant woman infected (microcephaly, blindness, heart defects). Prevention: MMR vaccine. [cite: 69]

Question 34

Viral Infection: Varicella Zoster (VZV) - Chickenpox

Answer 34

Causes chickenpox (childhood disease). [cite: 70] Transmission: Inhalation of airborne respiratory droplets. Highly contagious. Symptoms: Triad of rash, malaise, low-grade fever. Rash: Macules -> papules -> vesicles ("dewdrop on a rose petal") -> pustules -> crusts; often starts on scalp/trunk. Intense pruritus. Vaccine available. [cite: 70]

Question 35

Viral Infection: Varicella Zoster (VZV) - Shingles (Herpes Zoster)

Answer 35

Reactivation of dormant VZV (from prior chickenpox) in dorsal root ganglia, often in adulthood (stress, immunosuppression). [cite: 70] Symptoms: Painful, vesicular rash along a single nerve dermatome. Can lead to postherpetic neuralgia. Vaccine available for older adults. [cite: 70]

Question 36

Viral Infection: Erythema Infectiosum (Fifth Disease)

Answer 36

Caused by Human Parvovirus B19. [cite: 71] Common in childhood. Transmission: Droplet. Symptoms: Prodrome (headache, fever, pharyngitis). Classic "slapped-cheek" facial rash, then erythematous macular/morbilliform rash on extremities (lacy pattern when fading). Self-limiting. [cite: 71, 72]

Question 37

Viral Infection: Monkeypox

Answer 37

Caused by Monkeypox virus (Orthopoxvirus, similar to smallpox). [Text] Transmission: Close intimate contact (skin-to-skin with rash, body fluids, respiratory secretions), contaminated objects. Can be sexually transmitted. [Text] Symptoms: Resembles smallpox but with early lymph node enlargement. Fever, then vesicular rash (peripheral distribution). Lasts ~4 weeks. [Text] Smallpox vaccine offers prevention. [Text]

Question 38

Viral Infection: Herpes Simplex Virus (HSV-1 & HSV-2)

Answer 38

HSV-1 (common cold sore virus), HSV-2 (genital herpes). [cite: 72] Both cause acute (vesicular lesions with active virus) and latent infection (dormant in neurons, reactivates with stress/illness). [cite: 72] Transmission via direct contact with lesions/secretions. [Text]

Question 39

Viral Infection: Poliomyelitis (Polio)

Answer 39

Caused by Poliovirus. [cite: 73] Transmission: Fecal-oral. [cite: 73] Damages motor neurons. [cite: 73] Syndromes: Abortive (fever), Aseptic meningitis, Paralytic (asymmetrical flaccid paralysis, DTRs decreased/absent). [cite: 73] Vaccines available (injectable Salk, oral Sabin). Postpolio syndrome can occur later in life. [Text]

Question 40

Viral Infection: Hantavirus

Answer 40

Rodent-borne, transmission via inhalation of aerosolized virus from rodent urine/droppings/saliva. [cite: 74] Two syndromes: HFRS (hemorrhagic fever with renal syndrome - febrile, hypotensive, oliguric, diuretic, convalescent phases) and HCPS (hantavirus cardiopulmonary syndrome - more fatal, cardiovascular shock). [cite: 74]

Question 41

Viral Infection: West Nile Virus (WNV)

Answer 41

Spread by mosquito bites (mosquito bites infected bird, then human). [cite: 75] Range from asymptomatic to mild febrile syndrome to severe encephalitis/meningitis (highest risk in older, immunocompromised). [cite: 75] Symptoms: Fever, headache, body aches, swollen lymph nodes, rash. [cite: 76] Severe: Neck stiffness, disorientation, paralysis. [cite: 77] No vaccines/specific treatments. [cite: 75]

Question 42

Viral Infection: Ebola Virus

Answer 42

Filovirus causing severe hemorrhagic fever. [cite: 78] Zoonosis (primates, fruit bats), spread to humans by direct contact with blood/body fluids. [cite: 78] Symptoms: Vomiting, diarrhea, malaise, internal bleeding, fever. High mortality (up to 90%), death in 7-14 days. Immediate isolation needed. Experimental vaccine rVSV-ZEBOV. [cite: 78]

Question 43

Viral Infection: Marburg Virus

Answer 43

Filovirus causing Marburg hemorrhagic fever. [cite: 78] Similar to Ebola. Reservoir: African fruit bat. Transmission via contact with infected bodily fluids. [Text] Symptoms: Fever, headache, malaise -> rash -> jaundice, pancreatitis, delirium, hemorrhage. High mortality (up to 90%). No standard treatment. [cite: 78]

Question 44

Viral Infection: Zika Virus

Answer 44

Transmitted by mosquitos; also via sexual transmission. [cite: 79] Causes severe fetal defects if pregnant woman infected (microcephaly, brain defects). [cite: 79] Symptoms (if any): Fever, rash, muscle/joint pain, conjunctivitis, headache. Associated with Guillain-Barré syndrome. [Text]

Question 45

Fungal Infection: Candida (*Candida albicans*)

Answer 45

Part of normal flora (GI, vaginal). [cite: 80] Pathogenic with overgrowth (immunocompromised, antibiotic use). Superficial: Thrush (oropharyngeal candidiasis - white plaques), Vulvovaginal candidiasis (yeast infection - itching, white curd-like discharge), Balanitis. Systemic candidiasis: Bloodstream infection, can be fatal in immunocompromised. [cite: 80]

Question 46

Fungal Infection: Aspergillus (*Aspergillus fumigatus*)

Answer 46

Grows on plants, starchy foods. [cite: 80] Causes Aspergillosis in immunocompromised, critically ill (esp. hematological malignancies). Pulmonary disease (flu-like, fever, cough, chest pain, infiltrates). Forms: Allergic bronchopulmonary, Acute invasive, Disseminated invasive. [Text]

Question 47

Fungal Infection: Cryptococcus (*Cryptococcus neoformans*)

Answer 47

Encapsulated yeast. [cite: 81] Can cause meningitis or disseminated disease in immunocompromised (esp. AIDS). [cite: 81] Enters via respiratory inhalation, disseminates to brain (can cross BBB). [Text]

Question 48

Fungal Infection: Histoplasmosis (*Histoplasma capsulatum*)

Answer 48

Dimorphic fungus in soil (bird/bat areas). [cite: 81] "Darling’s disease." Most prevalent endemic mycosis in US. Most cases self-limiting. Immunosuppressed at risk for active/disseminated infection (liver, spleen, bone marrow, adrenals, GI, CNS). [cite: 81]

Question 49

Fungal Infection: Pneumocystis Pneumonia (PCP) (*Pneumocystis jirovecii*)

Answer 49

Caused by *P. jirovecii* (fungus, formerly protozoan). [cite: 82] Most common opportunistic infection in HIV/AIDS. [cite: 82] Normal respiratory inhabitant; proliferates in severe immunosuppression. Symptoms: Pneumonia (fever, dyspnea, cough, crackles, infiltrates). [Text]

Question 50

Fungal Infection: Coccidioidomycosis ("Valley Fever") (*Coccidioides immitis*)

Answer 50

Fungus in soil (SW US, Mexico, Central/South America). [cite: 82] Infection by inhalation of airborne spores. Symptoms: Flu-like (cough, fever, aches, headache), macular rash. Self-limited mostly. Immunosuppressed: can develop pneumonia, meningitis, bone/joint infection. [cite: 82]

Question 51

Parasitic Infection: Malaria (Plasmodium protozoan)

Answer 51

Transmitted by *Anopheles* mosquito. [cite: 83] Parasites invade liver, then RBCs (multiply, degrade Hgb). Causes RBC destruction -> jaundice, hemolytic anemia, hepatosplenomegaly. [cite: 83] Symptoms: Characteristic pattern of fever/chills every 2-3 days, headache, myalgia, nausea. [Text] Treatment: Chloroquine (resistance widespread), other regimens. Prophylaxis (mefloquine) for travelers. [cite: 83]

Question 52

Parasitic Infection: Toxoplasmosis (*Toxoplasma gondii* protozoan)

Answer 52

Primary host: cat (cysts in feces). [cite: 85] Transmission: Ingestion of cysts (cat litter, undercooked meat - pork/lamb/venison, contaminated water/utensils), congenital (mother to fetus - vision impairment, learning disabilities, death), organ transplant/transfusion. [Text] Symptoms: Mild flu-like in immunocompetent. Severe in immunocompromised (encephalitis, heart/liver/eye disease). [cite: 85]

Question 53

Parasitic Infection: Amebiasis (*Entamoeba histolytica*) & Giardiasis (*Giardia lamblia*)

Answer 53

Water-borne protozoan infections (contaminated food/water, fecal-oral route). [cite: 89] Cyst stage resistant to gastric acid. Trophozoites lyse GI epithelial cells. Often asymptomatic; can cause severe dysentery (nausea, vomiting, abdominal pain, copious watery/bloody diarrhea). [Text]

Question 54

Parasitic Infection: Leishmaniasis (*Leishmania* protozoan)

Answer 54

Sandflies are vectors (bite infected rodents, then humans). [cite: 89] Invades bloodstream, body organs. Asymptomatic common. Can cause fever, splenomegaly, lymphadenopathy, hepatomegaly, cachexia, gray skin discoloration. [cite: 89]

Question 55

Parasitic Infection: Helminths ("Worms") - General & Examples

Answer 55

Life cycle varies. Transmission direct or via environment/soil. More prevalent in tropical areas. Examples: Enterobiasis (pinworms - fecal-oral, perianal itching), Ascariasis (roundworm), Hookworm, Trichinosis (from undercooked meat - *Trichinella* worm invades muscle), Tapeworm (*Taenia saginata* from undercooked beef - depletes nutrients, cysticercosis if larvae migrate). [cite: 90]

Question 56

Prion Disease: Creutzfeldt-Jakob Disease (CJD)

Answer 56

Rare, fatal degenerative neurological disease caused by prions. [cite: 91] Progressive death of brain nerve cells; spongiform brain appearance. [cite: 91] Affects ages 45-75. Symptoms: Rapidly progressive dementia, memory loss, personality changes, hallucinations, speech impairment, myoclonus, ataxia, seizures. Fatal within months/weeks. No cure. [Text]

Question 57

Prion Disease: Variant Creutzfeldt-Jakob Disease (vCJD)

Answer 57

Newer form, affects younger people (avg. onset 33 yrs). [Text] Believed caused by same agent as Bovine Spongiform Encephalopathy (BSE). Symptoms: Psychiatric problems, sensory issues -> poor muscle coordination, spasms, mental confusion. Death avg. 13 months post-symptoms. [Text]

Question 58

Prion Disease: Bovine Spongiform Encephalopathy (BSE / "Mad Cow Disease")

Answer 58

Progressive neurological disorder of cattle, likely caused by prions. [cite: 91] Spread via contaminated meat-and-bone meal fed to cattle. [Text]