Surgical Infections Practice Questions

Q: Hypotension in a case of gas gangrene is best treated by?

Ringer's Lactate. **Explanation:** In gas gangrene (clostridial myonecrosis), hypotension is primarily driven by a massive shift of fluid from the intravascular to the extravascular space (third-spacing) and the systemic effects of alpha-toxins. This leads to **hypovolemic shock**. **1. Why Ringer’s Lactate (RL) is the Correct Choice:** RL is the preferred crystalloid for initial resuscitation in surgical infections and trauma. It is an **isotonic, balanced salt solution** that closely mimics the electrolyte composition of extracellular fluid. Unlike Normal Saline, RL contains lactate, which acts as a buffer against the metabolic acidosis often seen in septic/toxic shock. Large-volume resuscitation with RL is essential to restore circulating volume and maintain renal perfusion. **2. Why the Other Options are Incorrect:** * **Normal Saline (NS):** While isotonic, large volumes of NS can lead to **hyperchloremic metabolic acidosis**, which can exacerbate the existing acidotic state in a critically ill gas gangrene patient. * **Plasma:** While plasma can expand volume, it is not the first-line treatment for acute hypotension. It carries risks of transfusion-related lung injury (TRALI) and infections, and is reserved for correcting coagulopathies. * **Whole Blood:** This is indicated for hemorrhagic shock. In gas gangrene, the primary issue is fluid loss and toxemia, not acute blood loss (unless secondary to extensive debridement). **Clinical Pearls for NEET-PG:** * **Causative Agent:** *Clostridium perfringens* (most common). * **Pathognomonic Sign:** Crepitus on palpation and "gas shadows" along muscle planes on X-ray. * **Management Priority:** 1. Aggressive fluid resuscitation (RL); 2. High-dose Penicillin + Clindamycin; 3. **Emergency surgical debridement** (most definitive). * **Hyperbaric Oxygen (HBO):** Useful adjunct to inhibit the growth of anaerobic bacteria and stop toxin production.

Q: Which of the following statements is NOT true regarding a carbuncle?

It is typically caused by Streptococcus.. ### Explanation A **carbuncle** is a deep-seated infective gangrene of the subcutaneous tissue, typically involving a cluster of interconnected hair follicles. **1. Why Option D is the correct (False) statement:** The primary causative organism for a carbuncle is **Staphylococcus aureus**, not Streptococcus. While Streptococcus is the classic cause of spreading infections like cellulitis or erysipelas, Staphylococcus is known for producing coagulase, which leads to localized suppuration, abscess formation, and tissue necrosis—the hallmarks of a carbuncle. **2. Analysis of other options:** * **Option A (True):** A carbuncle is defined as **infective gangrene** of the subcutaneous fat. The infection spreads horizontally under the dense deep fascia and reaches the surface through multiple hair follicles, creating a characteristic "sieve-like" appearance. * **Option B (True):** As mentioned, *Staphylococcus aureus* is the most common pathogen. * **Option C (True):** **Diabetes mellitus** is the most significant predisposing factor. High blood sugar levels impair neutrophil function and provide a favorable environment for bacterial growth. Other risk factors include malnutrition and immunosuppression. ### NEET-PG High-Yield Pearls * **Common Site:** The **nape of the neck** and the **back** are the most common sites because the skin is thick and the subcutaneous tissue is dense and fibrous. * **Clinical Feature:** It presents as a painful, brawny, inflammatory induration that eventually discharges pus through multiple openings (**Cribriform appearance**). * **Management:** * Control of blood sugar is mandatory. * Antibiotics (anti-staphylococcal). * Surgical intervention: A **cruciate incision** is made to excise all necrotic tissue (debridement) until healthy bleeding edges are reached.

Q: What is the recommended treatment for streptococcal necrotizing fasciitis?

All of the above. **Explanation:** Streptococcal necrotizing fasciitis (Type II NF), often caused by *Streptococcus pyogenes* (Group A Strep), is a surgical emergency characterized by rapid, full-thickness destruction of fascia and fat. Management requires a multi-modal approach involving aggressive surgery and synergistic antibiotic therapy. 1. **Surgical Debridement (Option A):** This is the **most critical step**. Antibiotics cannot penetrate necrotic tissue due to thrombosed end-arteries. Early, aggressive, and often repeated surgical debridement is mandatory to source control the infection and prevent mortality. 2. **Penicillin (Option B):** Penicillin remains the drug of choice for *S. pyogenes* due to its bactericidal action against the cell wall. 3. **Clindamycin (Option C):** This is added for two specific reasons: * **The Eagle Effect:** Penicillin is less effective against bacteria in the stationary phase (high bacterial load). Clindamycin, a protein synthesis inhibitor, is not affected by the growth phase. * **Toxin Suppression:** It inhibits the production of bacterial exotoxins (superantigens) responsible for Streptococcal Toxic Shock Syndrome (STSS). **Why "All of the above" is correct:** Monotherapy is insufficient. The gold standard is **Emergency Debridement + Penicillin + Clindamycin.** **High-Yield Clinical Pearls for NEET-PG:** * **Clinical Sign:** "Pain out of proportion to physical findings" is the earliest hallmark. * **LRINEC Score:** Used to differentiate NF from cellulitis (includes CRP, WBC, Hemoglobin, Sodium, Creatinine, and Glucose). * **Type I vs. Type II:** Type I is polymicrobial (diabetics/elderly); Type II is monomicrobial (Strep/Staph, often in healthy individuals). * **Finger Test:** Lack of bleeding, "dishwater pus," and easy blunt dissection of fascia during surgery confirm the diagnosis.

Q: What is the best treatment to prevent gas gangrene?

Thorough debridement. **Explanation:** The primary pathophysiology of **Gas Gangrene (Clostridial Myonecrosis)** involves the proliferation of anaerobic *Clostridium perfringens* in devitalized, ischemic tissues. These bacteria thrive in low-oxygen environments (anaerobic conditions) created by necrotic debris, foreign bodies, and compromised blood supply. **1. Why Thorough Debridement is the Correct Answer:** The most effective way to prevent gas gangrene is to eliminate the environment where the bacteria grow. **Thorough debridement** (removal of all dead, devitalized tissue and foreign material) restores an aerobic environment and reduces the bacterial load. Since *Clostridia* cannot survive in well-oxygenated, viable tissue, surgical toilet and debridement remain the "gold standard" for prevention. **2. Why Other Options are Incorrect:** * **Antiserum:** Polyvalent antitoxins are largely ineffective for prophylaxis and have a high risk of serum sickness/anaphylaxis. They are not used routinely. * **Vaccination:** There is currently no effective human vaccine available for *Clostridium perfringens*. * **Antibiotics:** While intravenous Penicillin G or Clindamycin are used as *adjuncts*, they cannot reach the site of infection if the tissue is necrotic and lacks blood supply. Antibiotics alone cannot prevent gas gangrene without surgical intervention. **Clinical Pearls for NEET-PG:** * **Incubation Period:** Very short, typically **1–6 hours** (up to 3 days). * **Clinical Sign:** "Dishwater pus" (thin, serosanguinous discharge) and **crepitus** (gas in tissues). * **X-ray Finding:** Feather-like appearance of muscle fibers due to gas. * **Management Priority:** 1. Aggressive Debridement, 2. High-dose Penicillin, 3. Hyperbaric Oxygen (HBO) therapy.

Q: Post-splenectomy sepsis is common in patients with which of the following conditions?

All of the above. **Explanation:** **Overwhelming Post-Splenectomy Infection (OPSI)** is a life-threatening medical emergency characterized by a rapid, fulminant clinical course. The spleen plays a critical role in filtering encapsulated bacteria and producing opsonins (like tuftsin and properdin). While any splenectomized patient is at risk, the incidence of sepsis is significantly higher when the spleen is removed for **hematologic disorders** compared to trauma. **Why "All of the Above" is Correct:** The risk of OPSI is directly related to the underlying condition for which the splenectomy was performed: * **Thalassemia (Option B):** Carries the highest risk among the options. These patients often have underlying iron overload and immune dysfunction, making them highly susceptible to post-operative sepsis. * **Hereditary Spherocytosis (Option C):** As a chronic hemolytic anemia, it carries a significant risk, though generally lower than Thalassemia. * **ITP (Option A):** While the risk is lower compared to Thalassemia, patients with ITP are still at a higher risk of OPSI than the general population or trauma patients due to the loss of splenic clearance of opsonized pathogens. **High-Yield Clinical Pearls for NEET-PG:** * **Most Common Organism:** *Streptococcus pneumoniae* (50-90% of cases), followed by *Haemophilus influenzae* type B and *Neisseria meningitidis*. * **Timing:** The risk is highest in the first **2 years** post-surgery, but the risk remains lifelong. * **Prevention (Vaccination):** Ideally administered **2 weeks before** elective surgery or **2 weeks after** emergency surgery (to ensure adequate antibody response). * **Prophylaxis:** Daily oral penicillin is often recommended, especially in children, for at least 2 years post-splenectomy. * **Age Factor:** The risk of OPSI is highest in children under the age of 5.

Q: What is the primary objective in the management of septic shock?

Locating and eradicating the source of infection.. In the management of septic shock, the primary objective is **source control** (locating and eradicating the source of infection). While supportive measures are vital, the underlying pathophysiology of septic shock is a systemic inflammatory response triggered by a pathogen. Unless the nidus of infection—such as an abscess, necrotic tissue, or an infected catheter—is removed or drained, the inflammatory cascade will continue, leading to irreversible multi-organ dysfunction syndrome (MODS) and death. **Analysis of Options:** * **Option C (Correct):** Source control is the definitive treatment. Without it, fluid resuscitation and vasopressors are merely "buying time" rather than curing the patient. * **Option A (Incorrect):** Myocardial dysfunction can occur in late sepsis (septic cardiomyopathy), but maintaining it is a supportive goal, not the primary curative objective. * **Option B (Incorrect):** Fluid resuscitation is the *initial* step in the "Surviving Sepsis" bundles to restore perfusion, but it does not address the root cause of the shock. * **Option D (Incorrect):** This refers to the management of **Anaphylactic shock**, not septic shock. **High-Yield NEET-PG Pearls:** * **The "Golden Hour":** Antibiotics should be administered within **1 hour** of recognition. * **Fluid Resuscitation:** The standard initial bolus is **30 mL/kg** of crystalloids. * **Vasopressor of Choice:** **Norepinephrine** is the first-line agent if fluid resuscitation fails to maintain a Mean Arterial Pressure (MAP) ≥ 65 mmHg. * **Source Control Rule:** "Ubi pus, ibi evacua" (Where there is pus, evacuate it). This includes debridement, drainage, or removal of infected hardware.

Question 1

Hypotension in a case of gas gangrene is best treated by?

Accepted Answer

Ringer's Lactate

Answer

Normal Saline

Answer

Plasma

Answer

Whole Blood

Question 2

Which of the following statements is NOT true regarding a carbuncle?

Accepted Answer

It is typically caused by Streptococcus.

Answer

It is an infective gangrene of the subcutaneous tissue.

Answer

It is primarily caused by Staphylococcus.

Answer

Individuals with diabetes are more susceptible.

Question 3

A 34-year-old female patient presented with left leg pain. On examination, the area was erythematous, warm, and tender with indistinct borders. The doctor suspected cellulitis and started her on IV oxacillin. The doctor noted that the pain was disproportionate to the level of cellulitis, and hence admitted the patient. During the night, the patient developed hypotension, deranged renal function tests, and a deranged coagulation profile. X-ray and CT of the leg were conducted. Which is the most common organism causing the condition described?

Accepted Answer

Group A Streptococcus

Answer

Staphylococcus aureus

Answer

Pseudomonas aeruginosa

Answer

Group D Streptococcus

Question 4

What is the most common cause of a cold abscess of the chest wall?

Accepted Answer

Pott's spine

Answer

Tuberculous abscesses of the chest wall

Answer

Tuberculosis of the ribs

Answer

Intercostal lymphadenitis

Question 5

What is the recommended treatment for streptococcal necrotizing fasciitis?

Accepted Answer

All of the above

Answer

Surgical debridement

Answer

Penicillin

Answer

Clindamycin

Question 6

What is the best treatment to prevent gas gangrene?

Accepted Answer

Thorough debridement

Answer

Antiserum

Answer

Vaccination

Answer

Antibiotics

Question 7

Post-splenectomy sepsis is common in patients with which of the following conditions?

Accepted Answer

All of the above

Answer

Immune thrombocytopenic purpura (ITP)

Answer

Thalassemia

Answer

Hereditary spherocytosis

Question 8

Chronic thick-walled pyogenic abscess may be due to the following, except?

Accepted Answer

Virulent strains of organism

Answer

Presence of a foreign body

Answer

Prolonged antibiotic therapy

Answer

Inadequate drainage

Question 9

What is the primary objective in the management of septic shock?

Accepted Answer

Locating and eradicating the source of infection.

Answer

Maintaining myocardial function.

Answer

Ensuring sufficient fluid volume.

Answer

Identifying and removing the allergen.

Question 10

What are the most common types of infections following splenectomy?

Accepted Answer

Encapsulated bacteria

Answer

Unencapsulated bacteria

Answer

Gram-positive sepsis

Answer

Gram-negative bacteria

Surgical Infections — MCQs

Surgical Infections — MCQs

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