Surgical Infections Practice Questions

Q: In which condition is hyperbaric oxygen therapy useful?

Gas gangrene. **Explanation:** **Gas gangrene (Clostridial Myonecrosis)** is the primary surgical indication for Hyperbaric Oxygen Therapy (HBOT). The causative organism, *Clostridium perfringens*, is a gram-positive, spore-forming **obligate anaerobe**. HBOT works by increasing the partial pressure of oxygen in tissues to levels that are directly bactericidal and bacteriostatic to Clostridia. Furthermore, high oxygen tension inhibits the production of the **alpha-toxin** (lecithinase), which is responsible for the rapid tissue destruction and systemic toxicity seen in this condition. **Analysis of Incorrect Options:** * **Tetanus:** While caused by an anaerobe (*C. tetani*), the pathology is driven by the retrograde axonal transport of **tetanospasmin** to the CNS. HBOT does not neutralize fixed toxins or reverse the clinical spasms; management focuses on wound debridement, antibiotics, and supportive care (sedation/ventilation). * **Frostbite:** The primary treatment involves rapid rewarming in water (37-39°C) and preventing secondary infection. While HBOT is sometimes studied for late-stage microvascular injury, it is not a standard or first-line indication. * **Vincent’s Angina:** This is an acute necrotizing ulcerative gingivitis caused by a symbiotic infection of fusiform bacilli and spirochetes. It is effectively managed with oral hygiene, debridement, and systemic antibiotics (Metronidazole). **High-Yield Clinical Pearls for NEET-PG:** * **HBOT Mechanism:** It delivers 100% oxygen at pressures >1 atmosphere (usually 2–3 ATA). * **Other Indications:** Carbon monoxide poisoning, Decompression sickness (Bends), Air embolism, and Chronic non-healing wounds (e.g., Diabetic foot ulcers). * **Absolute Contraindication:** Untreated pneumothorax. * **Gas Gangrene Diagnosis:** Characterized by "woody" hard muscles, crepitus (gas in tissues), and a "dishwater" discharge with a sweetish odor. X-ray shows feathery patterns of gas.

Q: The intense pain associated with a felon occurs because of?

A closed space infection. ### Explanation **Correct Answer: B. A closed space infection** A **felon** is an acute abscess involving the pulp space of the distal phalanx. The underlying medical concept for the intense, throbbing pain is the unique anatomy of the fingertip. The pulp is divided into numerous small, non-compliant compartments by **vertical fibrous septa** that run from the periosteum of the distal phalanx to the skin. When an infection occurs, inflammatory edema and pus accumulate within these rigid compartments. Because the septa prevent the tissue from expanding, the **intracompartmental pressure** rises rapidly. This high pressure compresses the local nerve endings, resulting in excruciating, throbbing pain. **Analysis of Incorrect Options:** * **A. Bone involvement:** While a neglected felon can lead to osteomyelitis of the distal phalanx due to pressure necrosis of the nutrient artery, bone involvement is a *complication*, not the primary cause of the initial intense pain. * **C. Digital artery thrombosis:** This is a rare and late complication. While ischemia can cause pain, the characteristic "closed-space" pressure is the hallmark of a felon. * **D. Nail bed involvement:** Infection of the nail fold is termed **paronychia**. While painful, it does not involve the compartmentalized pulp space and thus typically lacks the intense pressure-driven pain of a felon. **Clinical Pearls for NEET-PG:** * **Treatment:** Early **Incision and Drainage (I&D)** is mandatory. The incision should be made where the pain is maximal, typically mid-lateral or longitudinal, ensuring the fibrous septa are divided to decompress the space. * **Complication:** If left untreated, the high pressure can cause **ischemic necrosis** of the distal phalanx (osteomyelitis). Note that the base of the phalanx is usually spared because its blood supply (epiphyseal vessels) enters proximal to the pulp space. * **Most common organism:** *Staphylococcus aureus*.

Q: Which is the commonest post-splenectomy infection?

Streptococcus pneumoniae. **Explanation:** The spleen plays a critical role in the immune system, particularly in filtering blood-borne pathogens and producing opsonins (like tuftsin and properdin) that facilitate the phagocytosis of **encapsulated organisms**. Following a splenectomy, patients are at a lifelong increased risk for **Overwhelming Post-Splenectomy Infection (OPSI)**. **Why Streptococcus pneumoniae is correct:** * **Streptococcus pneumoniae** is the most common cause of OPSI, accounting for approximately **50–90%** of all cases. It is an encapsulated, Gram-positive coccus. Because the spleen is the primary site for clearing opsonized bacteria from the circulation, its absence allows these organisms to multiply rapidly, leading to fulminant sepsis. **Why the other options are incorrect:** * **A & B (S. pyogenes and S. aureus):** While these are common causes of skin and soft tissue infections, they are not specifically associated with the loss of splenic filtration. They lack the polysaccharide capsule that necessitates splenic clearance. * **D (Pseudomonas aeruginosa):** This is a common healthcare-associated pathogen (especially in burns or cystic fibrosis) but is not a primary driver of post-splenectomy sepsis. **High-Yield Clinical Pearls for NEET-PG:** * **Other common organisms in OPSI:** *Haemophilus influenzae* type B and *Neisseria meningitidis* (the "SHiN" organisms). * **Prevention:** Vaccination against these three organisms is mandatory. Ideally, vaccines should be given **14 days before** elective surgery or **14 days after** emergency surgery. * **Prophylaxis:** Daily oral penicillin is often recommended, especially in children, for at least two years post-surgery or until age 5. * **Peripheral Smear Findings:** Look for **Howell-Jolly bodies**, Pappenheimer bodies, and Heinz bodies post-splenectomy.

Q: Which of the following is NOT a feature of necrotising fasciitis?

Erythema limited to the area of oedema. **Explanation:** Necrotizing Fasciitis (NF) is a life-threatening, rapidly progressive infection of the deep fascia and subcutaneous tissues. The hallmark of NF is that the **internal tissue destruction is far more extensive than what is visible on the skin surface.** **Why Option B is the Correct Answer:** In NF, the infection spreads rapidly along the deep fascial planes, well beyond the margins of superficial skin changes. Therefore, **erythema is NOT limited to the area of edema.** The skin may appear relatively normal or mildly erythematous while the underlying fascia is already necrotic. This "discrepancy" between superficial appearance and deep destruction is a key diagnostic clue. **Analysis of Incorrect Options:** * **A. Disproportionate pain:** This is often the earliest clinical sign. The patient experiences severe, excruciating pain that seems far worse than the visible skin findings (e.g., mild redness). * **C. Dishwater pus:** During surgical exploration, the presence of thin, foul-smelling, grayish-brown fluid (resembling dishwater) is a classic finding indicating liquefactive necrosis of the fascia. * **D. Crepitus:** Caused by gas-forming organisms (Type I NF), crepitus (a crunchy sensation on palpation) is a specific but late sign of the disease. **NEET-PG High-Yield Pearls:** * **LRINEC Score:** Used to distinguish NF from cellulitis (includes CRP, WBC, Hemoglobin, Sodium, Creatinine, and Glucose). * **Finger Test:** A bedside test where a small incision is made under local anesthesia; a positive test shows lack of bleeding, "dishwater" fluid, and easy blunt dissection of the fascia with a finger. * **Management:** The gold standard is **emergency surgical debridement** and broad-spectrum antibiotics. "Life over limb" is the surgical mantra. * **Fournier’s Gangrene:** A specific type of NF involving the perineum and scrotum.

Q: Universal (standard) precautions to be observed by surgeons for the prevention of hospital-acquired HIV infection include the following except?

Pre-operative screening of all patients for HIV. ### Explanation The concept of **Universal (Standard) Precautions** is based on the principle that all blood and body fluids should be treated as potentially infectious for HIV, HBV, and other blood-borne pathogens, regardless of the patient's known status. **Why Option D is the Correct Answer:** Pre-operative screening of all patients for HIV is **not** a component of universal precautions. Mandatory screening is discouraged because: 1. **Window Period:** A patient may test negative but still be infectious. 2. **False Security:** It may lead to a lapse in rigorous aseptic techniques if a patient is perceived as "low risk." 3. **Ethics:** Universal precautions are designed to protect healthcare workers regardless of the diagnosis, making routine screening unnecessary for safety purposes. **Analysis of Incorrect Options:** * **A. Wearing gloves and barrier precautions:** This is a cornerstone of universal precautions. Using gloves, gowns, masks, and protective eyewear prevents skin and mucous membrane exposure to infectious materials. * **B. Washing hands on contamination:** Immediate handwashing after contact with blood/body fluids or after removing gloves is mandatory to reduce the risk of transient colonization and transmission. * **C. Handling sharp instruments with care:** Most occupational HIV transmissions occur via needle-stick injuries. Precautions include not recapping needles by hand and using "no-touch" techniques during surgery. **High-Yield Clinical Pearls for NEET-PG:** * **Risk of Transmission after Percutaneous Injury:** * **HBV:** ~30% (Highest risk) * **HCV:** ~3% * **HIV:** ~0.3% (Lowest risk) * **Post-Exposure Prophylaxis (PEP) for HIV:** Should ideally be started within **2 hours** (maximum up to 72 hours) and continued for **28 days**. * **Most common site of injury:** Non-dominant index finger during suturing.

Question 1

In which condition is hyperbaric oxygen therapy useful?

Accepted Answer

Gas gangrene

Answer

Tetanus

Answer

Frostbite

Answer

Vincent's angina

Question 2

What is the tetanus prophylaxis for a contaminated wound in a partially immune person?

Accepted Answer

Tetanus toxoid single dose, Tetanus Immune Globulin, antibiotics

Answer

Tetanus toxoid single dose, antibiotics

Answer

Tetanus toxoid two doses, Tetanus Immune Globulin

Answer

Tetanus toxoid three doses, Tetanus Immune Globulin, antibiotics

Question 3

An antibioma is defined as:

Accepted Answer

An excess mass of fibrous tissue around an abscess, persistently treated by excessive or partly sterilized antibiotic.

Answer

An all-powerful antibiotic.

Answer

An antibiotic contaminant.

Answer

A malignant tumor caused by an antibiotic.

Question 4

The intense pain associated with a felon occurs because of?

Accepted Answer

A closed space infection

Answer

Bone involvement

Answer

Digital artery thrombosis

Answer

Nail bed involvement

Question 5

A 48-year-old man with a history of diabetes presents with a poorly healing right foot ulcer that has been present for 1 month and untreated. He denies fever or chills and reports mild pain at the ulcer site. His vital signs are: temperature 37.6 C (99.6 F), blood pressure 158/86 mm Hg, pulse 94/min, and respirations 18/min. The patient has diminished popliteal, posterior tibial, and dorsalis pedis pulses bilaterally, more pronounced on the right. He has soft tissue swelling around the first toe with a 1 x 1 cm ulcer at the tip of the toe, surrounded by erythema and purulent discharge. An x-ray film of the foot shows soft tissue swelling and signs of early bone destruction in the first metatarsal. What is the most likely cause of the bone destruction evidenced on the x-ray film?

Accepted Answer

Osteomyelitis

Answer

Osteitis deformans

Answer

Osteoarthritis

Answer

Osteomalacia

Question 6

Which is the commonest post-splenectomy infection?

Accepted Answer

Streptococcus pneumoniae

Answer

Streptococcus pyogenes

Answer

Staphylococcus aureus

Answer

Pseudomonas aeruginosa

Question 7

Which of the following statements about sepsis and septic shock is TRUE?

Accepted Answer

All of the above.

Answer

It is the commonest cause of death in surgical patients.

Answer

The main treatment is addressing the infection site.

Answer

It leads to organ dysfunction.

Question 8

Which of the following is NOT a feature of necrotising fasciitis?

Accepted Answer

Erythema limited to the area of oedema

Answer

Disproportionate pain

Answer

Dishwater pus

Answer

Crepitus

Question 9

Universal (standard) precautions to be observed by surgeons for the prevention of hospital-acquired HIV infection include the following except?

Accepted Answer

Pre-operative screening of all patients for HIV

Answer

Wearing gloves and other barrier precautions

Answer

Washing hands on contamination

Answer

Handling sharp instruments with care

Question 10

Which of the following are characteristic features of early sepsis?

Accepted Answer

Bradycardia, hypotension, and cold extremities

Answer

Confusion and restlessness, bradycardia, and hypotension

Answer

Confusion and restlessness, hypotension, and cold extremities

Answer

Bradycardia, hypotension, and sweating

Surgical Infections — MCQs

Surgical Infections — MCQs

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