Infection and Complications: Tetanus, Gangrene, Necrotizing Fasciitis, and Risk Factors Practice Questions

25 multiple-choice questions on Infection and complications: tetanus, gangrene, necrotizing fasciitis, and risk factors for paramedic and EMT students, from Chapter 32 (Soft-Tissue Trauma). Read each question, pick your answer, then tap Show answer to check it and read the explanation.

25 practice questions

1. Signs of a localized wound infection typically appear:

   1. A. Within 1 hour of the injury
   2. B. 24 to 72 hours after the injury
   3. C. About 2 weeks after the injury
   4. D. Immediately at the time of injury
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   Answer: B. 24 to 72 hours after the injury

   Bacteria need time to multiply, so redness, warmth, swelling, pus, and pain usually develop within 1 to 3 days. Findings in the first hour reflect the injury and normal inflammation, not infection.

2. Which wound is at the highest risk of infection?

   1. A. A clean kitchen-knife cut on the scalp
   2. B. A small paper cut on a finger
   3. C. A surgical incision closed in the OR
   4. D. A crush wound contaminated with soil
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   Answer: D. A crush wound contaminated with soil

   Devitalized tissue from crushing plus soil contamination gives bacteria a protected, nutrient-rich environment. Scalp wounds are low risk because of the scalp's rich blood supply.

3. Which patient has the greatest risk of developing a wound infection?

   1. A. A healthy 20-year-old with a clean scalp cut
   2. B. A 30-year-old with a facial abrasion
   3. C. A 25-year-old with a forearm incision
   4. D. A 68-year-old diabetic with a foot wound
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   Answer: D. A 68-year-old diabetic with a foot wound

   Diabetes impairs immune function and blood flow, and foot wounds have poor perfusion. Facial and scalp wounds heal well because of their vascularity.

4. Lymphangitis appearing after a hand wound is seen as:

   1. A. Red streaks extending up the arm
   2. B. A black, dry area of dead skin
   3. C. A crackling sensation under the skin
   4. D. Pale, cool fingertips
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   Answer: A. Red streaks extending up the arm

   Red streaks along the lymphatic channels indicate spread of infection toward the lymph nodes and require prompt antibiotics. Crackling under the skin suggests gas-forming infection, a different and more ominous finding.

5. A man with generalized tetanus has painful muscle spasms that are set off by noise and touch. During transport, you should:

   1. A. Keep lights bright to monitor spasms well
   2. B. Limit stimulation and guard the airway
   3. C. Give an antibiotic to stop the spasms
   4. D. Have him walk to the ambulance to relax
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   Answer: B. Limit stimulation and guard the airway

   Tetanus toxin blocks inhibitory nerve signals, so stimuli such as noise, light, and touch trigger severe spasms that can involve the larynx and breathing muscles. Keep the environment quiet and dim, be ready to manage the airway, and give benzodiazepines per protocol. Antibiotics do not stop toxin-mediated spasms, and exertion would worsen them.

6. The classic early sign of tetanus is:

   1. A. Flaccid paralysis of the legs
   2. B. A black wound with no pain
   3. C. Stiffness of the jaw muscles
   4. D. High fever with a rash
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   Answer: C. Stiffness of the jaw muscles

   Tetanus toxin blocks inhibitory nerve signals, causing trismus (lockjaw), then generalized muscle rigidity and spasms. Flaccid paralysis is the opposite of the rigid spasms tetanus produces.

7. Tetanus spores are most likely to cause disease in wounds that are:

   1. A. Shallow and well perfused
   2. B. Cleaned and closed promptly
   3. C. Located on the scalp
   4. D. Deep, dirty, and anaerobic
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   Answer: D. Deep, dirty, and anaerobic

   C. tetani is an anaerobe that thrives in deep punctures and devitalized tissue. Clean, well-perfused wounds have enough oxygen to inhibit it.

8. For a dirty wound, a tetanus booster is generally recommended if the last dose was more than:

   1. A. 5 years ago
   2. B. 6 months ago
   3. C. 1 year ago
   4. D. 20 years ago
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   Answer: A. 5 years ago

   Current CDC guidance is a booster every 10 years for clean minor wounds and after 5 years for contaminated or major wounds. The 10-year interval for clean wounds is the most common mix-up.

9. A 38-year-old has a contaminated puncture wound and cannot remember ever receiving a tetanus vaccine. The hospital will most likely give:

   1. A. Rabies vaccine and immune globulin
   2. B. Tetanus toxoid and immune globulin
   3. C. A course of oral antibiotics
   4. D. No treatment unless symptoms appear
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   Answer: B. Tetanus toxoid and immune globulin

   Patients with unknown or incomplete vaccination and a dirty wound need both active immunization and passive immune globulin. Antibiotics do not neutralize tetanus toxin.

10. A diabetic patient has two black toes. One toe is dry and shriveled; the other is swollen, foul-smelling, and draining. The swollen, draining toe most likely has:

    1. A. Dry gangrene, which is the most urgent
    2. B. Frostbite that rewarming will fix
    3. C. Wet gangrene, which is more urgent
    4. D. Cellulitis that needs oral antibiotics
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    Answer: C. Wet gangrene, which is more urgent

    Dry gangrene is ischemic tissue death that mummifies slowly and is usually not acutely infected. Wet gangrene is infected dead tissue, with swelling, odor, and drainage, and it can spread rapidly and cause sepsis, so it is more urgent. Black, dead tissue will not recover with rewarming, and wet gangrene needs urgent surgical care rather than oral antibiotics.

11. A 55-year-old has a crushed leg wound from 2 days ago. The skin is bronze, swollen, and very painful, and you feel crackling under the skin. You suspect:

    1. A. Simple cellulitis
    2. B. A healing hematoma
    3. C. Gas gangrene
    4. D. Contact dermatitis
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    Answer: C. Gas gangrene

    Subcutaneous crepitus from gas, severe pain, discolored skin, and a foul discharge in a crushed, devitalized wound point to clostridial gas gangrene. Cellulitis causes redness and warmth but not gas in the tissue.

12. A man who injects drugs under his skin has a warm, red, tender swelling on his arm that feels soft and fluid-filled in the center. This is most likely:

    1. A. A simple bruise from injecting
    2. B. A normal reaction to the needle
    3. C. A blood clot in a superficial vein
    4. D. An abscess that needs drainage
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    Answer: D. An abscess that needs drainage

    A fluctuant, warm, red, tender swelling at an injection site is an abscess, a walled-off collection of pus that usually needs incision and drainage. Injection drug users are also at risk of cellulitis, necrotizing infections, endocarditis, and sepsis, so check for fever and tachycardia. A bruise or thrombosed vein is not fluctuant, and this is not a normal reaction.

13. A day after a small cut on her index finger, a woman holds the finger slightly bent. It is swollen along its whole length, and trying to straighten it causes severe pain. You should suspect:

    1. A. Infection of the flexor tendon sheath
    2. B. A simple sprain of the finger joint
    3. C. Mild cellulitis that will clear alone
    4. D. A dislocated finger from the cut
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    Answer: A. Infection of the flexor tendon sheath

    A finger held flexed, uniform swelling, tenderness along the tendon sheath, and severe pain on passive extension (Kanavel signs) indicate flexor tenosynovitis, a surgical emergency that can destroy the tendon. A sprain or dislocation would follow joint trauma, and this is not a mild infection that will clear alone.

14. A heroin user who injects under the skin has an infected arm wound. Over two days he develops double vision, drooping eyelids, slurred speech, and then weakness spreading down his body. You should suspect:

    1. A. Opioid overdose
    2. B. Wound botulism
    3. C. Spinal cord injury
    4. D. Wound tetanus
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    Answer: B. Wound botulism

    Clostridium botulinum can grow in contaminated wounds, especially with subcutaneous injection of black tar heroin. Its toxin causes cranial nerve palsies followed by descending flaccid paralysis that can stop breathing. Opioid overdose does not cause cranial nerve palsies with descending weakness, a spinal injury causes weakness below a level, and tetanus causes rigidity and spasms rather than flaccid paralysis.

15. A 60-year-old with diabetes has a small leg wound from 2 days ago, now with spreading purple discoloration, severe pain, fever, HR 124, and BP 88/52. Your priority is:

    1. A. Treat for sepsis and transport
    2. B. Clean and dress the wound before moving
    3. C. Splint and elevate the leg, then reassess
    4. D. Advise follow-up with his physician
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    Answer: A. Treat for sepsis and transport

    This patient likely has necrotizing soft-tissue infection with septic shock and needs IV fluids, sepsis notification, and emergency surgery. Wound care, splinting, or elevation on scene delays transport for a patient who is already hypotensive, and outpatient follow-up is far too late.

16. Necrotizing fasciitis is definitively treated with:

    1. A. IV antibiotics alone without surgery
    2. B. Surgical debridement and IV antibiotics
    3. C. Hyperbaric oxygen as the main treatment step
    4. D. Oral antibiotics and follow-up at home
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    Answer: B. Surgical debridement and IV antibiotics

    Dead tissue must be removed surgically, and broad-spectrum IV antibiotics are needed. Oral antibiotics are too slow and cannot penetrate necrotic tissue. Antibiotics without surgery cannot clear dead tissue, and hyperbaric oxygen is at most an adjunct, not a replacement for debridement.

17. A patient has a red, warm, tender area spreading around a 3-day-old forearm wound. Before transport, a useful step for the receiving staff is to:

    1. A. Squeeze the wound to drain any fluid
    2. B. Cover the whole arm in a tight wrap
    3. C. Mark the red border and note the time
    4. D. Apply heat packs until the redness fades
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    Answer: C. Mark the red border and note the time

    Outlining the edge of the redness with a skin marker and noting the time lets the hospital judge how fast the infection is spreading, which guides urgency and treatment. Squeezing the wound can spread infection, tight wraps can impair circulation, and heat packs can burn or mask findings.

18. A 40-year-old has a 3-day-old shin abrasion with a warm, red, tender area spreading 5 cm around it, no pus, and normal vital signs. This is most consistent with:

    1. A. Necrotizing fasciitis
    2. B. Gas gangrene
    3. C. Compartment syndrome
    4. D. Cellulitis
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    Answer: D. Cellulitis

    Spreading warmth, redness, and tenderness around a wound without systemic signs is cellulitis, which needs antibiotics. Necrotizing fasciitis is the tempting choice, but it causes severe pain out of proportion, rapid progression, and systemic illness.

19. A 52-year-old who smokes two packs a day has a slow-healing shin laceration. Smoking impairs his wound healing mainly by:

    1. A. Thinning the blood so that the wound keeps oozing
    2. B. Constricting vessels and lowering oxygen delivery
    3. C. Speeding collagen formation into a weak scar
    4. D. Raising skin temperature around the wound
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    Answer: B. Constricting vessels and lowering oxygen delivery

    Nicotine constricts small vessels, and carbon monoxide binds hemoglobin, so less oxygen reaches the wound; smoking also impairs white cell and fibroblast function, which slows healing and raises infection risk. Smoking makes platelets stickier, so it does not thin the blood. It slows collagen formation rather than speeding it. Vasoconstriction lowers, not raises, skin temperature.

20. A 26-year-old has a laceration he cleaned at home with hydrogen peroxide several times a day. He asks if this helps. You explain that peroxide:

    1. A. Is the preferred agent for cleaning wounds
    2. B. Prevents tetanus from developing later
    3. C. Can damage healthy tissue and slow healing
    4. D. Seals the wound against outside bacteria
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    Answer: C. Can damage healthy tissue and slow healing

    Hydrogen peroxide is cytotoxic to fibroblasts and healing cells; clean water and mild soap are preferred. It does not prevent tetanus, which requires vaccination.

21. A patient with a hand wound from 3 days ago has fever, red streaks up the forearm, and tender lymph nodes in the axilla. This indicates:

    1. A. Spreading infection needing prompt care
    2. B. A normal part of the wound healing process
    3. C. Local cellulitis that can wait a week
    4. D. A superficial vein clot from the wound
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    Answer: A. Spreading infection needing prompt care

    Lymphangitis and lymphadenitis with fever show that infection is spreading systemically and needs antibiotics. Normal healing does not cause red streaks or fever. The infection has moved beyond the wound, so it is not local cellulitis that can wait, and a superficial vein clot does not explain fever with tender axillary nodes.

22. Foreign material left in a wound increases infection risk because it:

    1. A. Speeds up the process of wound healing
    2. B. Releases natural antibiotic chemicals
    3. C. Improves oxygen delivery to the tissue
    4. D. Shields bacteria from immune cells
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    Answer: D. Shields bacteria from immune cells

    Debris such as gravel, wood, or clothing gives bacteria a place to grow out of reach of white cells. This is why wounds are irrigated and debrided.

23. A 3-day-old leg laceration that was never treated is now red, warm, and draining pus. At the hospital this wound will most likely be:

    1. A. Sutured tightly closed to seal out bacteria
    2. B. Glued shut with tissue adhesive right away
    3. C. Sealed under an occlusive dressing for days
    4. D. Opened, cleaned, and left open to heal
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    Answer: D. Opened, cleaned, and left open to heal

    An infected wound needs drainage, irrigation, and debridement, and is then left open to heal by secondary intention or closed later (delayed primary or tertiary closure) once the infection clears. Suturing an infected wound traps bacteria and pus and can turn cellulitis into an abscess. Tissue adhesive seals the surface the same way. An occlusive dressing left on for days holds in purulent drainage; dressings over an infected wound should absorb drainage and be changed.

24. A patient with a puncture wound to the sole of the foot through a sneaker is at risk for infection with:

    1. A. Pasteurella multocida
    2. B. Eikenella corrodens
    3. C. Pseudomonas aeruginosa
    4. D. Neisseria meningitidis
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    Answer: C. Pseudomonas aeruginosa

    Puncture wounds through rubber shoe soles are classically linked to Pseudomonas, which can cause bone and cartilage infection, especially in children. Staphylococcus aureus is the most common soft-tissue pathogen overall, but it is not offered here, and Pasteurella is associated with animal bites.

25. Which early finding most suggests a developing systemic infection from a wound?

    1. A. Fever and tachycardia
    2. B. Mild redness at the wound edges
    3. C. Swelling limited to the wound
    4. D. Mild itching at the wound
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    Answer: A. Fever and tachycardia

    Fever and tachycardia indicate a systemic response and may signal sepsis. Mild redness, swelling, or itching confined to the wound are local findings that can occur with normal healing or a local infection, but they do not show that infection has spread through the body.