Infectious Disease Processes Practice Questions

63 multiple-choice questions on Infectious disease processes for paramedic and EMT students, from Chapter 9 (Pathophysiology). Read each question, pick your answer, then tap Show answer to check it and read the explanation.

63 practice questions

1. Virulence refers to:

   1. A. The route by which it spreads
   2. B. How many people become infected
   3. C. The time from exposure to symptoms
   4. D. Degree of disease an organism causes
   Show answer

   Answer: D. Degree of disease an organism causes

   Virulence is the strength of an organism's ability to cause disease; a highly virulent organism causes disease in more exposed hosts.

2. Colonization means:

   1. A. Active infection with tissue damage
   2. B. Organisms present without disease
   3. C. Immunity after a past infection
   4. D. Spread of organisms to a new host
   Show answer

   Answer: B. Organisms present without disease

   A colonized patient may still transmit organisms.

3. Bacteremia refers to:

   1. A. Bacteria growing in the urine
   2. B. Bacteria colonizing the skin
   3. C. Bacterial toxins in the tissues
   4. D. Bacteria in the bloodstream
   Show answer

   Answer: D. Bacteria in the bloodstream

   Sepsis is the body's dysregulated response to infection.

4. Sepsis is best described as:

   1. A. Organ dysfunction from infection
   2. B. Any infection accompanied by a fever
   3. C. Bacteria present in the bloodstream alone
   4. D. A high fever with chills and sweating
   Show answer

   Answer: A. Organ dysfunction from infection

   Sepsis is life-threatening organ dysfunction caused by a dysregulated host response to infection. It may begin with subtle changes in mental status and vital signs.

5. Early signs of sepsis may include:

   1. A. Hypotension with cold, mottled skin
   2. B. Slow, deep respirations
   3. C. Tachycardia, tachypnea, and confusion
   4. D. Localized pain without vital sign changes
   Show answer

   Answer: C. Tachycardia, tachypnea, and confusion

   Fever or hypothermia, tachycardia, tachypnea, and altered mental status are early signs; older adults may present only with confusion or weakness. Hypotension with cold, mottled skin is a late sign of septic shock, and breathing becomes faster, not slower.

6. Septic shock is distinguished by:

   1. A. Positive blood cultures with fever
   2. B. Hypotension despite fluids
   3. C. Fever above 104°F with chills
   4. D. Tachycardia above 120 beats/min
   Show answer

   Answer: B. Hypotension despite fluids

   Septic shock is persistent hypotension and hypoperfusion despite adequate fluid resuscitation. Mortality is high, and time to antibiotics matters.

7. Viruses differ from bacteria in that viruses:

   1. A. Have a rigid peptidoglycan cell wall
   2. B. Must invade a host cell to reproduce
   3. C. Are generally larger than bacteria
   4. D. Respond to antibiotic treatment
   Show answer

   Answer: B. Must invade a host cell to reproduce

   That is why antibiotics do not help viral infections.

8. Antibiotic resistance develops because:

   1. A. The drug weakens the patient's immunity
   2. B. Antibiotic molecules mutate over time
   3. C. Resistant organisms survive and multiply
   4. D. Patients develop immunity to the drug
   Show answer

   Answer: C. Resistant organisms survive and multiply

   Antibiotics kill susceptible organisms while resistant ones survive and multiply. Unnecessary prescriptions accelerate it.

9. A localized infection may become systemic when:

   1. A. The abscess stays walled off
   2. B. The abscess drains to the outside
   3. C. Antibodies neutralize the toxins
   4. D. Organisms enter the blood
   Show answer

   Answer: D. Organisms enter the blood

   Cellulitis progressing to sepsis is a common path. Organisms or their toxins entering the bloodstream allow spread throughout the body. Drainage to the outside and neutralizing antibodies both help contain an infection.

10. The stages of infectious disease generally proceed as:

    1. A. Illness, latency, then incubation
    2. B. Recovery, exposure, then illness
    3. C. Prodrome, exposure, then incubation
    4. D. Exposure, incubation, prodrome, illness
    Show answer

    Answer: D. Exposure, incubation, prodrome, illness

    Exposure is followed by incubation, prodrome, illness, and then recovery or latency. Transmission risk varies by stage.

11. Pathogenicity refers to:

    1. A. The route by which it is transmitted
    2. B. How severe the disease tends to be
    3. C. The length of the incubation period
    4. D. An organism's ability to cause disease
    Show answer

    Answer: D. An organism's ability to cause disease

    Pathogenicity is whether an organism can cause disease; virulence is how severe that disease is. Some organisms are pathogenic only in certain hosts.

12. An opportunistic pathogen:

    1. A. Is transmitted mainly by insects
    2. B. Is highly virulent in healthy hosts
    3. C. Causes disease when defenses are weak
    4. D. Is a toxin rather than a living organism
    Show answer

    Answer: C. Causes disease when defenses are weak

    Opportunistic pathogens cause disease only when host defenses are weakened, e.g., Pneumocystis in HIV. Most are normal flora or environmental organisms that rarely harm healthy people and are not spread mainly by insects. They are living organisms, not toxins.

13. Normal flora:

    1. A. Live mainly in the bloodstream
    2. B. Usually protect against pathogens
    3. C. Consist mostly of fungi and viruses
    4. D. Are eliminated by a healthy immune system
    Show answer

    Answer: B. Usually protect against pathogens

    Normal flora are organisms that normally inhabit the body and often protect against pathogens. Antibiotics disrupting them allows C. difficile. They live on the skin and mucosal surfaces, not in the normally sterile blood, and are mostly bacteria.

14. Infection differs from colonization because infection:

    1. A. Requires organisms to be in the blood
    2. B. Always produces obvious symptoms
    3. C. Causes no harm or immune response in the host
    4. D. Involves multiplication with tissue damage
    Show answer

    Answer: D. Involves multiplication with tissue damage

    Infection involves organism multiplication with tissue damage or an immune response; colonization is presence without disease.

15. A patient exposed to measles 10 days ago now has fever, cough, and red eyes but no rash yet. Which stage of infection is this?

    1. A. Prodromal
    2. B. Incubation
    3. C. Convalescence
    4. D. Latent
    Show answer

    Answer: A. Prodromal

    The prodrome is the period of vague early symptoms before the characteristic illness. For measles it comes before the rash, and the patient is already contagious. Incubation is the symptom-free period after exposure. Convalescence is recovery. Latency is dormancy with possible later reactivation.

16. The prodromal stage involves:

    1. A. Vague early symptoms
    2. B. No symptoms while organisms multiply
    3. C. Gradual recovery of strength
    4. D. Peak, disease-specific symptoms
    Show answer

    Answer: A. Vague early symptoms

    The prodrome brings early, nonspecific symptoms such as fatigue and malaise; the patient may be contagious. The silent multiplication phase is incubation.

17. Latent infection means:

    1. A. Dormant organism that can reactivate
    2. B. The organism is actively multiplying
    3. C. The organism has been fully cleared
    4. D. Symptoms persist with no organism
    Show answer

    Answer: A. Dormant organism that can reactivate

    Latent organisms are present but inactive, capable of reactivation, as with herpes viruses and tuberculosis.

18. Reactivation of latent infection occurs with:

    1. A. Completing an antibiotic course
    2. B. Antiviral prophylaxis
    3. C. A recent booster vaccination series
    4. D. Immunosuppression, stress, or aging
    Show answer

    Answer: D. Immunosuppression, stress, or aging

    Shingles from latent varicella. Antibiotics do not reactivate latent viruses, and antiviral prophylaxis is used to prevent reactivation.

19. Local infection:

    1. A. Spreads through the bloodstream
    2. B. Typically progresses to sepsis
    3. C. Is always severe and rapid
    4. D. Stays confined to one area
    Show answer

    Answer: D. Stays confined to one area

    Cellulitis or an abscess.

20. Systemic infection:

    1. A. Spreads via the blood or lymph
    2. B. Is always mild and self-limited
    3. C. Stays confined to the entry site
    4. D. Affects only the skin surface
    Show answer

    Answer: A. Spreads via the blood or lymph

    Sepsis is the extreme.

21. Bacteria are classified by:

    1. A. The host species they infect
    2. B. Size alone, measured in microns
    3. C. Color of the colonies alone
    4. D. Shape, Gram stain, oxygen use
    Show answer

    Answer: D. Shape, Gram stain, oxygen use

    Bacteria are classified by shape, gram stain reaction, oxygen requirements, and other features, which guides antibiotic selection.

22. Gram-positive bacteria:

    1. A. Lack any cell wall at all
    2. B. Have an outer membrane with endotoxin
    3. C. Have a thick wall and stain purple
    4. D. Stain pink after counterstaining
    Show answer

    Answer: C. Have a thick wall and stain purple

    Gram-positive bacteria have a thick peptidoglycan wall that holds the purple stain, e.g., Staphylococcus and Streptococcus.

23. Gram-negative bacteria:

    1. A. Are reliably sensitive to plain penicillin
    2. B. Lack a cell wall entirely
    3. C. Have a thick wall and stain purple
    4. D. Have an outer membrane with endotoxin
    Show answer

    Answer: D. Have an outer membrane with endotoxin

    Gram-negative bacteria have a thin wall with an outer membrane containing endotoxin and stain pink, e.g., E. coli and Pseudomonas.

24. Aerobic bacteria:

    1. A. Are killed by any oxygen
    2. B. Require no oxygen to grow
    3. C. Require oxygen to grow
    4. D. Need host cells to reproduce
    Show answer

    Answer: C. Require oxygen to grow

    Most skin organisms. Needing a host cell to reproduce describes viruses, not bacteria.

25. Anaerobic bacteria:

    1. A. Grow best in well-oxygenated tissue
    2. B. Grow without oxygen
    3. C. Cannot form spores
    4. D. Need oxygen to survive
    Show answer

    Answer: B. Grow without oxygen

    Anaerobes grow without oxygen and cause deep tissue infections, e.g., Clostridium species. They thrive in poorly oxygenated tissue, and some, such as Clostridium, form spores.

26. Bacterial spores:

    1. A. Are dormant, highly resistant forms
    2. B. Are fragile and easily destroyed
    3. C. Are a reproductive stage of viruses
    4. D. Are killed by alcohol hand gel
    Show answer

    Answer: A. Are dormant, highly resistant forms

    Spores are dormant, highly resistant forms that survive harsh conditions, e.g., C. difficile and anthrax. Alcohol gel does not kill them; wash with soap and water.

27. Why are antibiotics ineffective against influenza?

    1. A. Influenza is caused by a fungus, not a bacterium
    2. B. Viruses have thick cell walls that block the drugs
    3. C. Influenza resists them from overuse
    4. D. Viruses replicate inside host cells, out of reach
    Show answer

    Answer: D. Viruses replicate inside host cells, out of reach

    Viruses have no cell wall or ribosomes of their own; they use the host cell's machinery to reproduce. Antibiotics target structures unique to bacteria, so they do nothing against viruses. Antivirals such as oseltamivir work on viral targets. Influenza is not fungal. Overuse breeds resistance in bacteria; antibiotics never acted on influenza in the first place.

28. Viral infection can cause disease by:

    1. A. Only malignant transformation of cells
    2. B. Only immune-mediated tissue damage
    3. C. Cell lysis as the only mechanism
    4. D. Lysis, dysfunction, or immune damage
    Show answer

    Answer: D. Lysis, dysfunction, or immune damage

    Viruses cause disease through cell lysis, altered cell function, transformation to cancer, or immune-mediated damage.

29. Oncogenic viruses:

    1. A. Exist only in animals, not humans
    2. B. Are always fatal within months
    3. C. Cause only short-lived acute illness
    4. D. Can cause cancer, as HPV does
    Show answer

    Answer: D. Can cause cancer, as HPV does

    Vaccination prevents some cancers. Hepatitis B is another example, linked to liver cancer.

30. Fungal infections are most serious in:

    1. A. Immunocompromised people
    2. B. Athletes with athlete's foot
    3. C. People with seasonal allergies
    4. D. Recently vaccinated adults
    Show answer

    Answer: A. Immunocompromised people

    Candida and Aspergillus. Athlete's foot is a common but minor fungal infection. Allergies and vaccination do not weaken defenses against fungi.

31. Parasitic infections include:

    1. A. Respiratory viruses
    2. B. Yeasts and molds
    3. C. Gram-negative bacteria
    4. D. Protozoa and helminths
    Show answer

    Answer: D. Protozoa and helminths

    Parasites include protozoa (e.g., malaria) and helminths (worms). Travel history matters.

32. Prions are:

    1. A. Very small DNA viruses
    2. B. Spore-forming fungi
    3. C. Infectious misfolded proteins
    4. D. Bacteria lacking a cell wall
    Show answer

    Answer: C. Infectious misfolded proteins

    Prions are infectious misfolded proteins causing neurodegenerative disease such as Creutzfeldt-Jakob disease.

33. Antibiotics target:

    1. A. Structures unique to bacteria
    2. B. All microorganisms equally
    3. C. Viral replication machinery
    4. D. Fungal cell membrane sterols
    Show answer

    Answer: A. Structures unique to bacteria

    Antibiotics target bacterial structures or processes absent in human cells: cell walls, ribosomes, DNA synthesis.

34. Broad-spectrum antibiotics:

    1. A. Have fewer side effects than narrow agents
    2. B. Target only one specific organism
    3. C. Affect many bacteria, including flora
    4. D. Are always the preferred first choice
    Show answer

    Answer: C. Affect many bacteria, including flora

    Resistance and C. difficile risk.

35. Antibiotic resistance mechanisms include:

    1. A. Antibiotics breaking down in the blood
    2. B. Patients developing drug tolerance
    3. C. Enzymes, altered targets, and efflux pumps
    4. D. Increased host antibody production
    Show answer

    Answer: C. Enzymes, altered targets, and efflux pumps

    Bacteria resist through enzyme production, altered targets, efflux pumps, and reduced permeability, and they share resistance genes.

36. MRSA stands for:

    1. A. Methicillin-resistant Staphylococcus aureus
    2. B. Multi-drug resistant skin agent
    3. C. Multiple resistant Staphylococcus aureus
    4. D. Methicillin-related Staphylococcal skin abscess
    Show answer

    Answer: A. Methicillin-resistant Staphylococcus aureus

    Community and hospital strains.

37. Sepsis differs from bacteremia because sepsis involves:

    1. A. No organisms anywhere in the body
    2. B. Only bacteria present in the blood
    3. C. A localized infection without spread
    4. D. Organ dysfunction from the host response
    Show answer

    Answer: D. Organ dysfunction from the host response

    In sepsis, the body's dysregulated response causes organ dysfunction; the host response is the problem.

38. Sepsis screening criteria commonly include:

    1. A. Infection plus abnormal vitals or mentation
    2. B. An elevated lactate as the only marker
    3. C. Hypotension without any other findings
    4. D. Fever above 38.3°C as the sole criterion
    Show answer

    Answer: A. Infection plus abnormal vitals or mentation

    Screens combine suspected infection with abnormal temperature, heart rate, respiratory rate, or mental status (qSOFA and SIRS criteria).

39. Sepsis mortality increases with:

    1. A. Each hour of delay in treatment
    2. B. Younger patient age
    3. C. Higher fever at the time of presentation
    4. D. A normal initial lactate
    Show answer

    Answer: A. Each hour of delay in treatment

    Mortality rises with each hour of delay in antibiotics and fluids. Time matters as in stroke and MI. Septic patients who are hypothermic tend to do worse than those with fever, and a normal lactate suggests lower rather than higher risk.

40. Septic shock requires:

    1. A. Fluids alone, repeated until pressure improves
    2. B. Vasopressors alone, withholding fluids
    3. C. Fluids, pressors, antibiotics, source control
    4. D. Antibiotics alone, withholding fluids
    Show answer

    Answer: C. Fluids, pressors, antibiotics, source control

    Septic shock requires fluids, vasopressors, antibiotics, and source control; all components matter.

41. Common sources of sepsis include:

    1. A. The abdomen almost exclusively
    2. B. The urinary tract almost exclusively
    3. C. Lungs, urinary tract, gut, skin
    4. D. The skin almost exclusively
    Show answer

    Answer: C. Lungs, urinary tract, gut, skin

    Pneumonia is the most common.

42. Sepsis in older adults may present with:

    1. A. No changes until shock develops
    2. B. Classic textbook sepsis signs
    3. C. High fever and shaking chills
    4. D. Confusion, weakness, or falls
    Show answer

    Answer: D. Confusion, weakness, or falls

    Older adults often present atypically with confusion, weakness, or falls, sometimes without fever.

43. Sepsis in infants may present with:

    1. A. A high fever in every case
    2. B. No signs until late shock
    3. C. Classic adult signs such as shaking rigors
    4. D. Poor feeding, lethargy, or hypothermia
    Show answer

    Answer: D. Poor feeding, lethargy, or hypothermia

    Infants may show poor feeding, lethargy, hypothermia, or irritability: nonspecific and dangerous.

44. Meningitis causes:

    1. A. Infection of the skin and fat layer
    2. B. Inflammation of the lung parenchyma
    3. C. Inflamed meninges, stiff neck
    4. D. Inflammation of the bladder wall
    Show answer

    Answer: C. Inflamed meninges, stiff neck

    Meningitis causes headache, stiff neck, fever, and altered mental status; bacterial meningitis is a medical emergency.

45. Petechial rash with fever suggests:

    1. A. Prickly heat rash
    2. B. A benign viral exanthem
    3. C. Meningococcemia
    4. D. An allergic drug reaction
    Show answer

    Answer: C. Meningococcemia

    Rapidly fatal without treatment.

46. Pneumonia pathophysiology involves:

    1. A. Collapse of alveoli from lost surfactant
    2. B. Exudate filling the alveoli
    3. C. Fluid collecting in the pleural space
    4. D. Airway narrowing from bronchospasm
    Show answer

    Answer: B. Exudate filling the alveoli

    Inflammatory exudate fills alveoli, causing consolidation and impaired gas exchange.

47. Urinary tract infection ascends from:

    1. A. The bloodstream into the kidneys
    2. B. The kidneys down to the bladder
    3. C. The bowel wall directly into the bladder
    4. D. The urethra to the bladder and kidneys
    Show answer

    Answer: D. The urethra to the bladder and kidneys

    Women are more affected because of urethral length.

48. Cellulitis involves:

    1. A. Bone and bone marrow
    2. B. Joint capsule and synovium
    3. C. Skin and subcutaneous tissue
    4. D. Deep muscle and fascia
    Show answer

    Answer: C. Skin and subcutaneous tissue

    Cellulitis infects skin and subcutaneous tissue, causing redness, warmth, and swelling. Mark the borders to track spread.

49. Necrotizing fasciitis:

    1. A. Involves only the epidermis
    2. B. Usually resolves with oral antibiotics
    3. C. Spreads fast; pain exceeds findings
    4. D. Is a mild, self-limited skin rash
    Show answer

    Answer: C. Spreads fast; pain exceeds findings

    Necrotizing fasciitis is a rapidly progressive deep infection; pain out of proportion to findings is a key clue. Surgical emergency.

50. An abscess is:

    1. A. A walled-off collection of pus
    2. B. A viral blister under the skin
    3. C. A diffuse spreading skin infection
    4. D. A clot within a superficial vein
    Show answer

    Answer: A. A walled-off collection of pus

    Drainage is the treatment.

51. Endocarditis risk factors include:

    1. A. Young age with normal valves
    2. B. Well-controlled hypertension
    3. C. Recent viral upper respiratory infection
    4. D. IV drug use and prosthetic valves
    Show answer

    Answer: D. IV drug use and prosthetic valves

    IV drug use, prosthetic valves, and prior valve damage are risk factors. Look for fever with a new murmur. Controlled hypertension and a recent cold do not seed the valves with bacteria.

52. Osteomyelitis:

    1. A. Is an infection of the joint space
    2. B. Is a bone infection, hard to treat
    3. C. Is usually cured by a short oral course
    4. D. Is usually caused by a virus
    Show answer

    Answer: B. Is a bone infection, hard to treat

    Diabetic foot. Infection of the joint space is septic arthritis. Bone infection often needs weeks of IV antibiotics and sometimes surgery.

53. Tuberculosis pathophysiology involves:

    1. A. Rapid lobar pneumonia within days
    2. B. Granulomas walling off the organism
    3. C. Toxin release without tissue invasion
    4. D. Spread mainly through blood transfusion
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    Answer: B. Granulomas walling off the organism

    TB triggers granuloma formation that may contain the organism; latent TB can reactivate decades later. TB invades tissue and spreads by airborne droplets, not by toxins alone or through transfusion.

54. HIV pathophysiology involves:

    1. A. Destruction of antibody-making B cells
    2. B. Direct destruction of neutrophils
    3. C. Destruction of red blood cells
    4. D. Progressive loss of helper T cells
    Show answer

    Answer: D. Progressive loss of helper T cells

    HIV progressively destroys helper (CD4) T cells, leading to immunodeficiency; AIDS is the advanced stage. B-cell function suffers because it depends on helper T cells, but B cells and neutrophils are not HIV's main target.

55. Hepatitis pathophysiology involves:

    1. A. Bile duct blockage by gallstones
    2. B. Liver cell injury and inflammation
    3. C. Pancreatic autodigestion by enzymes
    4. D. Gallbladder wall inflammation
    Show answer

    Answer: B. Liver cell injury and inflammation

    Hepatitis is liver cell injury and inflammation causing jaundice and impaired function; chronic forms lead to cirrhosis and cancer. Gallstone blockage is choledocholithiasis, autodigestion is pancreatitis, and gallbladder inflammation is cholecystitis.

56. Influenza complications include:

    1. A. Rheumatic heart disease
    2. B. Pneumonia and worsening chronic disease
    3. C. Lifelong latent reactivation, like shingles
    4. D. Chronic hepatitis and cirrhosis
    Show answer

    Answer: B. Pneumonia and worsening chronic disease

    Complications include pneumonia, dehydration, and worsening of chronic conditions, especially in older adults and those with chronic disease. Rheumatic heart disease follows strep infection, latency with reactivation is typical of herpesviruses such as varicella, and chronic hepatitis follows hepatitis B or C.

57. Gastroenteritis pathophysiology involves:

    1. A. Gastric acid eroding the stomach lining
    2. B. Intestinal inflammation with fluid loss
    3. C. Inflammation of the appendix
    4. D. Liver injury causing jaundice
    Show answer

    Answer: B. Intestinal inflammation with fluid loss

    Intestinal inflammation causes vomiting, diarrhea, and fluid loss. Dehydration is the danger. Acid erosion of the stomach lining is peptic ulcer disease, and an inflamed appendix is appendicitis.

58. Clostridioides difficile infection follows:

    1. A. Antibiotics disrupting gut flora
    2. B. A recent viral respiratory illness
    3. C. Eating undercooked poultry
    4. D. Drinking contaminated well water
    Show answer

    Answer: A. Antibiotics disrupting gut flora

    Antibiotic use disrupts normal gut flora, allowing C. difficile overgrowth and severe diarrhea. Undercooked poultry is linked to Salmonella and Campylobacter, and contaminated water to organisms such as Giardia.

59. Lyme disease is transmitted by:

    1. A. Flea bites
    2. B. Skin contact
    3. C. Mosquito bites
    4. D. Tick bites
    Show answer

    Answer: D. Tick bites

    Bull's-eye rash.

60. Rabies pathophysiology involves:

    1. A. Gut infection from contaminated food
    2. B. A localized skin infection at the bite
    3. C. Viral pneumonia after inhalation
    4. D. Viral spread along nerves to the brain
    Show answer

    Answer: D. Viral spread along nerves to the brain

    Rabies spreads along nerves to the brain and is nearly always fatal once symptoms begin; post-exposure prophylaxis prevents it.

61. Tetanus pathophysiology involves:

    1. A. Toxin blocking acetylcholine release
    2. B. An allergic reaction to the wound
    3. C. Bacteria spreading through the blood
    4. D. Toxin blocking inhibitory neurons
    Show answer

    Answer: D. Toxin blocking inhibitory neurons

    Tetanus toxin blocks inhibitory neurons, causing muscle spasm and rigidity. Blocking acetylcholine release is botulism. Vaccination prevents it.

62. Botulism pathophysiology involves:

    1. A. High fever with meningeal irritation
    2. B. Toxin blocking acetylcholine release
    3. C. Widespread nerve inflammation
    4. D. Toxin blocking inhibitory neurons
    Show answer

    Answer: B. Toxin blocking acetylcholine release

    Botulinum toxin blocks acetylcholine release, causing descending flaccid paralysis and respiratory failure.

63. Emerging infections are concerning because:

    1. A. No immunity or proven treatment exists
    2. B. They are usually mild and self-limited
    3. C. They are always caused by viruses
    4. D. They are too rare to spread widely
    Show answer

    Answer: A. No immunity or proven treatment exists

    No population immunity exists and treatments may be unavailable, so pandemics can result.