Surgical Infections — MCQs

Surgical Infections Indian Medical PG Practice Questions and MCQs

Question 21: All of the following are included in the criteria for systemic inflammatory response syndrome (SIRS), EXCEPT?

A. Hypothermia
B. Leukopenia
C. Tachycardia
D. Thrombocytopenia (Correct Answer)

Explanation: **Explanation:** The **Systemic Inflammatory Response Syndrome (SIRS)** is a clinical syndrome representing the body's generalized inflammatory response to various insults (infectious or non-infectious). The diagnosis requires at least **two** of the following four criteria: 1. **Temperature:** $>38^\circ\text{C}$ (Hyperthermia) or $<36^\circ\text{C}$ (**Hypothermia**). 2. **Heart Rate:** $>90$ beats per minute (**Tachycardia**). 3. **Respiratory Rate:** $>20$ breaths per minute or $PaCO_2 <32\text{ mmHg}$ (Tachypnea). 4. **White Blood Cell Count:** $>12,000/\text{mm}^3$ (Leukocytosis), $<4,000/\text{mm}^3$ (**Leukopenia**), or $>10\%$ immature (band) forms. **Why Thrombocytopenia is the correct answer:** While thrombocytopenia (low platelet count) is a significant marker for organ dysfunction and is a component of the **SOFA (Sequential Organ Failure Assessment) score** used to define Sepsis-3, it is **not** part of the original SIRS criteria. **Analysis of Incorrect Options:** * **A. Hypothermia:** Included; it reflects a failure of thermoregulation in severe inflammatory states. * **B. Leukopenia:** Included; a low WBC count often signifies overwhelming infection or bone marrow exhaustion. * **C. Tachycardia:** Included; it is one of the earliest and most sensitive signs of systemic stress. **High-Yield Clinical Pearls for NEET-PG:** * **Sepsis-3 Definition:** Sepsis is now defined as life-threatening organ dysfunction caused by a dysregulated host response to infection (SOFA score $\ge 2$). The SIRS criteria are no longer the primary tool for defining sepsis but remain clinically useful for screening. * **qSOFA (Quick SOFA):** Includes Respiratory rate $\ge 22$, Altered Mentation (GCS $<15$), and Systolic BP $\le 100\text{ mmHg}$. * **Most common cause of SIRS:** Infection (Sepsis), but it can also be caused by pancreatitis, trauma, or burns.

Question 22: Which of the following can precipitate an anaerobic infection?

A. Trauma
B. Impaired circulation
C. Tissue necrosis
D. All of the above (Correct Answer)

Explanation: **Explanation:** The core requirement for the growth and multiplication of **obligate anaerobes** is a low oxygen tension environment (low redox potential or Eh). Under normal physiological conditions, healthy tissue is well-oxygenated, which inhibits the growth of these organisms. **Why "All of the Above" is correct:** Anaerobic infections are typically endogenous and occur when normal mucosal barriers are breached and the local environment becomes hypoxic. * **Trauma (Option A):** Physical injury disrupts the integrity of skin or mucosa, allowing commensal anaerobes to enter deeper tissues. It also causes local edema and hemorrhage, which increases tissue pressure and reduces oxygen delivery. * **Impaired Circulation (Option B):** Ischemia is a primary driver for anaerobic growth. Reduced blood flow (due to vascular disease, tight dressings, or shock) leads to a rapid drop in tissue oxygen levels, creating an ideal niche for organisms like *Bacteroides* or *Clostridium*. * **Tissue Necrosis (Option C):** Dead tissue lacks a blood supply and serves as a nutrient-rich, oxygen-free medium. Necrotic debris further lowers the redox potential, facilitating the rapid spread of infection. **Clinical Pearls for NEET-PG:** * **Synergy:** Anaerobic infections are often **polymicrobial**. Aerobic bacteria (like *E. coli*) consume available oxygen, further lowering the redox potential and "paving the way" for anaerobes. * **Clinical Clues:** Foul-smelling (putrid) discharge, gas in tissues (crepitus), and infection near mucosal surfaces are hallmarks of anaerobic involvement. * **Common Pathogens:** *Bacteroides fragilis* (most common in intra-abdominal sepsis) and *Clostridium perfringens* (gas gangrene). * **Treatment:** Requires surgical debridement (to remove necrotic tissue/restore Eh) and antibiotics like Metronidazole, Clindamycin, or Carbapenems.

Question 23: Phlegmon; all are true except?

A. The tissue is tender, painful, and hard to touch.
B. Pain, fever, and malaise are aggressive.
C. It is a rapidly spreading infection of subcutaneous tissue due to micro-organisms like staphylococci. (Correct Answer)
D. Is caused due to micro-organisms which are capable of producing hyaluronidase that breaks down the intercellular cementing substance hyaluronic acid.

Explanation: ### Explanation **Phlegmon** is a non-circumscribed, spreading inflammatory mass of soft tissue. It represents a stage of inflammation that has not yet localized into a fluctuant abscess. **1. Why Option C is the Correct Answer (The False Statement):** Phlegmon is primarily caused by **Streptococci** (specifically *Streptococcus pyogenes*), not Staphylococci. Streptococci produce enzymes like **hyaluronidase** and **streptokinase**, which dissolve connective tissue and fibrin, allowing the infection to spread rapidly through tissue planes. In contrast, *Staphylococcus aureus* produces **coagulase**, which clots plasma and tends to localize the infection, leading to abscess formation rather than a spreading phlegmon. **2. Analysis of Other Options:** * **Option A:** True. Clinically, a phlegmon presents as a firm, indurated, and exquisitely tender area. Unlike an abscess, there is no "soft center" or fluctuation because the pus is not yet localized. * **Option B:** True. Because the infection is spreading and lacks a protective wall, there is significant systemic absorption of toxins, leading to high-grade fever, severe pain, and malaise. * **Option C:** True. The hallmark of phlegmonous spread is the production of **hyaluronidase** (Duran-Reynal’s factor). This enzyme breaks down hyaluronic acid in the intercellular matrix, facilitating the rapid "seeping" of the infection across anatomical barriers. **Clinical Pearls for NEET-PG:** * **Phlegmon vs. Abscess:** Phlegmon is diffuse/spreading; Abscess is localized/fluctuant. * **Common Sites:** Most commonly seen in the **Appendix** (Appendicular phlegmon) and **Pancreas** (Pancreatic phlegmon). * **Management:** Initial management is usually conservative (antibiotics and rest). If it fails to resolve, it may progress to an abscess requiring drainage. * **Key Enzyme:** Remember **Hyaluronidase = Spreading factor** (associated with Streptococcus).

Question 24: What is the classification of Type IIIc according to the Southam grading system?

A. Erythema along sutures
B. Large volume of serosanguinous discharge (Correct Answer)
C. Prolonged serosanguinous discharge
D. Pus at one point

Explanation: The **Southam grading system** is a clinical classification used to assess the severity of surgical site infections (SSIs) based on the nature and volume of wound discharge and the presence of inflammation. ### Explanation of the Correct Answer **Option B (Large volume of serosanguinous discharge)** is the correct definition for **Type IIIc**. In the Southam system, Type III is characterized by serosanguinous discharge. This is further sub-classified by duration and volume: * **IIIa:** Prolonged serosanguinous discharge. * **IIIb:** Intermittent serosanguinous discharge. * **IIIc:** Large volume of serosanguinous discharge. ### Why Other Options are Incorrect * **Option A (Erythema along sutures):** This corresponds to **Type I** (Minor inflammation/Redness). * **Option C (Prolonged serosanguinous discharge):** This corresponds to **Type IIIa**. * **Option D (Pus at one point):** This corresponds to **Type IV** (Minor clinical infection/Localized pus). ### High-Yield Facts for NEET-PG The Southam Grading is a frequent "match the following" or "direct recall" topic. Memorize this simplified table: | Grade | Clinical Feature | | :--- | :--- | | **Type 0** | Normal healing | | **Type I** | Erythema/Redness along sutures | | **Type II** | Erythema with induration | | **Type III** | Serosanguinous discharge (**IIIa:** Prolonged; **IIIb:** Intermittent; **IIIc:** Large volume) | | **Type IV** | Minor infection (Pus at one point <2cm) | | **Type V** | Major infection (Pus >2cm or deep-seated) | **Clinical Pearl:** While the CDC classification (Superficial, Deep, Organ Space) is the gold standard for reporting SSIs, the Southam system remains high-yield for exams focusing on clinical wound assessment. Large volume serosanguinous discharge (IIIc) is often a precursor to wound dehiscence.

Question 25: Cytokines are secreted in sepsis and Systemic Inflammatory Response syndrome (SIRS) by which of the following?

A. Neutrophils (Correct Answer)
B. Adrenal gland
C. Platelets
D. Collecting duct

Explanation: ### Explanation In the context of sepsis and Systemic Inflammatory Response Syndrome (SIRS), the body’s innate immune system is activated to release a cascade of inflammatory mediators. **Neutrophils** (along with macrophages and monocytes) are the primary cellular sources of cytokines. When triggered by Pathogen-Associated Molecular Patterns (PAMPs) or Damage-Associated Molecular Patterns (DAMPs), these leukocytes secrete pro-inflammatory cytokines such as **TNF-α, IL-1, and IL-6**. These mediators are responsible for the systemic manifestations of SIRS, including fever, tachycardia, and vasodilation. **Analysis of Incorrect Options:** * **B. Adrenal gland:** While the adrenal glands are crucial in the stress response (secreting cortisol and catecholamines like adrenaline), they do not primarily secrete cytokines. Cortisol actually functions to *downregulate* the cytokine response. * **C. Platelets:** Platelets are primarily involved in hemostasis and the release of growth factors (like PDGF). While they interact with leukocytes, they are not the principal source of the systemic cytokines defining SIRS. * **D. Collecting duct:** This is a functional unit of the kidney involved in water reabsorption and electrolyte balance; it has no role in cytokine production during sepsis. **NEET-PG High-Yield Pearls:** * **TNF-α (Tumor Necrosis Factor-alpha):** The first and most important cytokine released in the systemic inflammatory response. * **IL-6:** The primary cytokine responsible for inducing the **Acute Phase Response** (e.g., stimulating the liver to produce CRP). * **SIRS Criteria:** Defined by abnormalities in temperature, heart rate, respiratory rate, and WBC count (often driven by neutrophil activity). * **Macrophage:** Often considered the "master orchestrator" of the cytokine storm alongside neutrophils.

Question 26: In a surgical patient, which of the following is NOT a cause of non-surgical infection?

A. Lower respiratory tract infection
B. Wound infection (Correct Answer)
C. Clostridium difficile diarrhea
D. Urinary tract infection

Explanation: In surgical practice, infections are broadly classified into two categories based on their relationship to the operative procedure: **Surgical Site Infections (SSIs)** and **Non-surgical (Remote) Infections.** ### Why "Wound Infection" is the Correct Answer A **Wound Infection** (now formally termed Surgical Site Infection) is defined as an infection occurring at the site of surgery within 30 days of the procedure (or up to 90 days if an implant is used). Because it is directly related to the surgical incision or the manipulated organ/space, it is classified as a **Surgical Infection**. ### Analysis of Incorrect Options (Non-Surgical Infections) Non-surgical infections are nosocomial (hospital-acquired) infections that occur in surgical patients but are not related to the operative site itself. * **A. Lower Respiratory Tract Infection:** Often manifests as postoperative pneumonia or atelectasis-related infection. It is a systemic complication, not a site-specific surgical infection. * **C. Clostridium difficile diarrhea:** This is a healthcare-associated infection typically triggered by perioperative antibiotic use, affecting the gastrointestinal flora rather than the surgical wound. * **D. Urinary Tract Infection (UTI):** Usually associated with indwelling Foley catheters (CAUTI). It is the most common nosocomial infection in surgical patients but is categorized as a remote/non-surgical infection. ### NEET-PG High-Yield Pearls * **Most common non-surgical infection:** Urinary Tract Infection (UTI). * **Most common surgical infection:** Surgical Site Infection (SSI). * **SSI Classification:** 1. **Superficial Incisional:** Involves skin and subcutaneous tissue. 2. **Deep Incisional:** Involves fascia and muscle. 3. **Organ/Space:** Involves any part of the anatomy opened or manipulated. * **Timing:** Most non-surgical infections (like UTI or Pneumonia) appear within the first 48–72 hours post-op, whereas SSIs typically manifest between post-op days 5 and 10.

Question 27: An abscess that arises from a tuberculous origin is known as which of the following?

A. Cystic hygroma.
B. Collar stud abscess.
C. Cold abscess. (Correct Answer)
D. Laryngocele.

Explanation: **Explanation:** A **Cold Abscess** is a hallmark clinical presentation of tuberculosis (TB). Unlike pyogenic abscesses, which are characterized by the classic signs of inflammation—heat, redness, and pain—a tuberculous abscess lacks these features because it does not trigger an acute inflammatory response. It is formed by the liquefaction necrosis (caseation) of tuberculous granulomas, most commonly occurring in the cervical lymph nodes or as a result of spinal tuberculosis (Pott’s disease). **Analysis of Options:** * **Cold Abscess (Correct):** It is "cold" because there is no overlying warmth or erythema. It is typically fluctuant and may eventually track to the skin. * **Collar Stud Abscess:** This is a specific *stage* of a cold abscess. It occurs when a deep-seated tuberculous lymph node ruptures through the deep fascia, creating a superficial collection connected to the deep one by a narrow track. While related to TB, "Cold Abscess" is the broader term for the origin itself. * **Cystic Hygroma:** A congenital multilocular lymphatic malformation, usually found in the posterior triangle of the neck in children. It transilluminates brilliantly. * **Laryngocele:** A dilatation of the laryngeal saccule filled with air (or mucus). It presents as a neck swelling that increases in size with increased endolaryngeal pressure (e.g., Valsalva maneuver). **High-Yield Clinical Pearls for NEET-PG:** * **Most common site:** Cervical lymph nodes (Scrofula). * **Pott’s Disease:** A cold abscess in the lumbar spine may track down the psoas sheath to present as a swelling in the groin (**Psoas Abscess**). * **Management:** Never perform simple Incision and Drainage (I&D) for a cold abscess, as it leads to a persistent **non-healing sinus**. The preferred treatment is aspiration through healthy skin (Z-track technique) and Anti-Tubercular Therapy (ATT).

Question 28: Following a boating injury in an industrial-use river, a patient presents with fever, tachycardia, and a rapidly expanding area of erythema, blistering, and drainage from a flank wound. An x-ray shows gas in the soft tissues. Which of the following measures is most appropriate?

A. Administration of an antifungal agent
B. Administration of antitoxin
C. Wide debridement (Correct Answer)
D. Administration of hyperbaric oxygen

Explanation: ### Explanation The clinical presentation of fever, tachycardia, rapidly spreading erythema, blistering, and **gas in the soft tissues** (crepitus/radiographic finding) following a contaminated injury is diagnostic of **Necrotizing Soft Tissue Infection (NSTI)**, likely Clostridial myonecrosis (Gas Gangrene). **1. Why Wide Debridement is Correct:** NSTIs are surgical emergencies. The underlying pathophysiology involves rapid bacterial multiplication and toxin release leading to tissue ischemia and necrosis. Because antibiotics cannot penetrate necrotic, avascular tissue, **immediate and aggressive surgical debridement** of all non-viable tissue is the single most important factor in reducing mortality. "Source control" is the priority; without it, the patient will succumb to septic shock. **2. Why Other Options are Incorrect:** * **A. Antifungal agent:** These infections are typically polymicrobial (Type I) or monomicrobial (Type II - e.g., *S. pyogenes* or *Clostridium*). Fungi are rarely the primary cause in acute trauma. * **B. Antitoxin:** While toxins (like alpha-toxin) drive the disease, there is no commercially available antitoxin that replaces the need for surgery. (Note: Tetanus toxoid is supportive but not the primary treatment for active gas gangrene). * **D. Hyperbaric Oxygen (HBO):** While HBO can inhibit anaerobic growth and toxin production, it is strictly an **adjunct**. It must never delay definitive surgical debridement. **Clinical Pearls for NEET-PG:** * **Pathognomonic sign:** Crepitus on palpation or "dishwater pus" drainage. * **Radiology:** X-ray showing "feathery" gas patterns along fascial planes. * **Microbiology:** *Clostridium perfringens* is the most common cause of gas gangrene; *Streptococcus pyogenes* is the most common cause of necrotizing fasciitis. * **Management Rule:** "Life over limb." If debridement is insufficient, amputation may be necessary. Antibiotics (Penicillin + Clindamycin) should be started immediately but only after the decision for surgery is made.

Question 29: Which organism is responsible for the destruction of skin grafts?

A. Streptococcus (Correct Answer)
B. Staphylococcus
C. Pseudomonas
D. Clostridium

Explanation: **Explanation:** The correct answer is **Streptococcus (specifically Group A Beta-hemolytic Streptococcus)**. **1. Why Streptococcus is the correct answer:** Streptococcus pyogenes produces potent extracellular enzymes, most notably **streptokinase** and **hyaluronidase** (the "spreading factor"). These enzymes dissolve fibrin and degrade the intercellular matrix (hyaluronic acid) of the connective tissue. In the context of skin grafting, fibrin is essential for the initial "fibrin anchorage" or "plasmatic imbibition" phase, where the graft adheres to the recipient bed. By dissolving this fibrin glue, Streptococcus prevents graft take and leads to rapid, complete destruction of the graft. **2. Why the other options are incorrect:** * **Staphylococcus:** While *Staphylococcus aureus* is a common cause of surgical site infections, it typically produces **coagulase**, which promotes fibrin clotting and leads to localized abscess formation. It is less likely than Streptococcus to cause widespread graft loss. * **Pseudomonas:** This organism is known for producing a characteristic blue-green discharge (pyocyanin). While it can cause graft failure due to heavy exudate and biofilm formation, it is not as classically associated with the rapid enzymatic destruction of the fibrin layer as Streptococcus. * **Clostridium:** These are anaerobic organisms primarily associated with gas gangrene (C. perfringens) or tetanus. They are not common primary pathogens in the superficial destruction of skin grafts. **3. Clinical Pearls for NEET-PG:** * **The "Graft Killer":** In surgical literature, Streptococcus is often referred to as the most dangerous organism for skin grafts. * **Quantitative Threshold:** A bacterial count of **>10⁵ organisms per gram of tissue** in the wound bed is generally considered the threshold for graft failure. However, for **Streptococcus**, even a lower concentration can cause total graft loss. * **Clinical Sign:** If a graft appears to be "melting" or sliding off the wound bed within the first 24-48 hours, suspect a Streptococcal infection.

Question 30: What is bacteremia?

A. Common after anastomotic breakdown
B. Dangerous if the patient has a prosthesis, which can become infected
C. May be associated with systemic organ failure
D. All of the above (Correct Answer)

Explanation: **Explanation:** Bacteremia is defined as the presence of viable bacteria in the bloodstream. It is a critical concept in surgical infections, often serving as the precursor to sepsis. * **Option A:** Anastomotic breakdown (e.g., after a bowel resection) leads to the leakage of contaminated contents into the peritoneal cavity. This results in peritonitis, where the high bacterial load and inflammatory response facilitate the translocation of bacteria into the systemic circulation, causing bacteremia. * **Option B:** This is a high-yield clinical fact. Bacteria in the blood can seed onto foreign bodies via "hematogenous spread." Patients with prosthetic heart valves, joint replacements, or vascular grafts are at high risk of developing **biofilm-associated infections**, which are notoriously difficult to treat and often require surgical removal of the prosthesis. * **Option C:** If the host immune response fails to contain the bacteremia, it progresses to **Sepsis** and **Septic Shock**. This triggers a systemic inflammatory response syndrome (SIRS) that leads to multi-organ dysfunction syndrome (MODS) and potential organ failure (renal, hepatic, or respiratory). Since all statements accurately describe the clinical implications and risks associated with bacteremia, **Option D** is the correct answer. **NEET-PG High-Yield Pearls:** * **Transient Bacteremia:** Can occur even during routine activities like tooth brushing or minor procedures like catheterization. * **Sepsis vs. Bacteremia:** Bacteremia is a microbiological diagnosis (positive blood culture), whereas sepsis is a clinical diagnosis (organ dysfunction caused by a dysregulated host response to infection). * **Most common cause of Catheter-Related Bloodstream Infection (CRBSI):** *Staphylococcus epidermidis* (Coagulase-negative Staph).

Practice by Chapter

Surgical Site Infections

Practice Questions

Intra-abdominal Infections

Practice Questions

Soft Tissue Infections

Practice Questions

Necrotizing Soft Tissue Infections

Practice Questions

Surgical Sepsis

Practice Questions

Tetanus Prophylaxis

Practice Questions

Antimicrobial Prophylaxis

Practice Questions

Antimicrobial Therapy in Surgical Infections

Practice Questions

Surgical Drainage Procedures

Practice Questions

Infection Control in Operating Room

Practice Questions

Biofilms and Implant-Related Infections

Practice Questions

Prevention Strategies

Practice Questions

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