Surgical Infections — MCQs

Surgical Infections Indian Medical PG Practice Questions and MCQs

Question 31: Which of the following is NOT considered a risk factor for developing Surgical Site Infections (SSIs)?

A. General anesthesia (Correct Answer)
B. Prolonged duration of procedure
C. Malnutrition
D. Bacterial contamination

Explanation: **Explanation:** Surgical Site Infections (SSIs) are influenced by a triad of factors: host characteristics, procedure-related variables, and the microbial environment. **Why General Anesthesia is the correct answer:** General anesthesia itself is not an independent risk factor for SSIs. While the physiological stress of surgery and the choice of anesthetic agents can influence the immune response, the **mode of anesthesia** (General vs. Spinal/Local) does not directly correlate with increased infection rates. In contrast, factors that impair tissue perfusion or oxygenation during anesthesia (like hypothermia or hypoxia) are the actual risks, rather than the anesthetic technique itself. **Why the other options are incorrect:** * **Prolonged duration of procedure:** This is a classic risk factor. Longer surgeries increase the time tissues are exposed to the environment, increase the likelihood of bacterial seeding, and often correlate with increased blood loss and tissue trauma. * **Malnutrition:** A low serum albumin level (<3.5 g/dL) or significant weight loss impairs wound healing and blunts the immune response, making the patient highly susceptible to infection. * **Bacterial contamination:** The "dose" of bacteria is critical. Whether through endogenous flora (e.g., bowel opening) or exogenous breaks in sterile technique, higher bacterial loads directly increase SSI risk. **High-Yield Clinical Pearls for NEET-PG:** * **Classification:** SSIs are divided into Superficial Incisional, Deep Incisional, and Organ/Space infections. * **Timing:** Most SSIs occur within 30 days of surgery (or up to 1 year if an implant is used). * **Most Common Organism:** *Staphylococcus aureus* is the most common overall; however, in colorectal surgery, Gram-negative bacilli and anaerobes predominate. * **Modifiable Risk Factors:** Smoking cessation (at least 4 weeks pre-op), glycemic control (HbA1c <7%), and maintaining normothermia are crucial for prevention.

Question 32: Antibioma is best treated by?

A. Partial resection
B. Complete resection (Correct Answer)
C. Aspiration
D. Administration of antibiotics

Explanation: **Explanation:** An **Antibioma** is a tough, fibrous mass that forms when an acute abscess is treated with antibiotics without prior surgical drainage. The antibiotics sterilize the pus or suppress the infection, but the body reacts by walling off the area with dense fibrous tissue, resulting in a painless or mildly tender, firm, non-fluctuant swelling. **Why Complete Resection is the Correct Answer:** Once an antibioma has formed, the thick, avascular fibrous capsule prevents further antibiotic penetration. Since the contents are often organized or semi-solid rather than liquid pus, simple drainage is usually ineffective. **Complete surgical excision (resection)** of the entire mass along with its capsule is the definitive treatment to ensure resolution and prevent recurrence. **Analysis of Incorrect Options:** * **Partial Resection:** This is avoided as it leaves behind infected or necrotic tissue and the fibrous capsule, which can lead to chronic sinus formation or recurrence. * **Aspiration:** Antibiomas are solid or semi-solid masses with thick walls. Aspiration typically fails because the contents are too thick to pass through a needle and the capsule will not collapse. * **Administration of Antibiotics:** This is the original cause of the condition. Further antibiotics cannot penetrate the dense, poorly vascularized fibrous wall, making medical management ineffective at this stage. **Clinical Pearls for NEET-PG:** * **Common Site:** Most frequently encountered in the **breast** (following inadequate treatment of a breast abscess). * **Clinical Mimic:** In the breast, an antibioma can clinically mimic a **carcinoma** due to its firm, fixed nature; hence, excision and biopsy are crucial. * **Prevention:** The gold standard for abscess management is always **Incision and Drainage (I&D)**; antibiotics should be an adjunct, not a replacement for drainage.

Question 33: Which of the following classifications is used for wound grading?

A. Rank and Wakefield classification
B. SEPSIS grading
C. Southampton grading (Correct Answer)
D. None of the above

Explanation: ### Explanation **1. Why Southampton Grading is Correct:** The **Southampton Wound Assessment Scale** is a widely used clinical classification system specifically designed to grade the severity of **Surgical Site Infections (SSI)**. It categorizes wound healing based on clinical observation, ranging from normal healing to major destruction of deep tissues. * **Grade 0:** Normal healing. * **Grade I:** Normal healing with mild bruising or erythema. * **Grade II:** Erythema plus other signs of inflammation. * **Grade III:** Clear or serosanguinous discharge. * **Grade IV:** Purulent discharge (pus). * **Grade V:** Deep tissue breakdown (Dehiscence). **2. Why Other Options are Incorrect:** * **Rank and Wakefield Classification:** This is used in plastic and reconstructive surgery to classify **primary and secondary wound closure** (specifically regarding the timing and nature of skin grafts/flaps), not for grading infection severity. * **SEPSIS Grading:** While "Sepsis" refers to a systemic inflammatory response to infection, there is no specific "SEPSIS grading" for local surgical wounds. Clinical tools like **qSOFA** or **SIRS** criteria are used for systemic assessment, not wound grading. **3. Clinical Pearls for NEET-PG:** * **ASEPSIS Score:** Another high-yield scoring system for SSIs. It is more objective than Southampton as it assigns numerical points to parameters like serous discharge, erythema, purulence, and the use of antibiotics. * **CDC Classification of SSI:** Categorizes infections into **Superficial Incisional**, **Deep Incisional**, and **Organ/Space** infections. * **Crucial Timing:** Most surgical site infections manifest between **5 to 10 days** postoperatively. * **Most Common Organism:** *Staphylococcus aureus* remains the most common cause of SSI overall.

Question 34: A 36-year-old male patient presents with swelling in the submandibular region, elevated tongue, dysphagia, and high fever. Intraoral examination reveals a grossly destructed lower first molar. What is the primary purpose of performing a culture and sensitivity test in this scenario?

A. To assess the overall severity of the infection
B. To determine if the current antibiotic dosage is sufficient
C. To identify the antibiotic to which the causative organism is most sensitive or least resistant (Correct Answer)
D. To guide the decision on when to discontinue antibiotic therapy

Explanation: **Explanation:** The clinical presentation—submandibular swelling, elevated tongue (due to sublingual space involvement), dysphagia, and a dental source (lower molar)—is classic for **Ludwig’s Angina**. This is a rapidly spreading cellulitis of the submandibular, sublingual, and submental spaces. **1. Why the Correct Answer is Right:** Ludwig’s Angina is typically a **polymicrobial infection** involving both aerobic and anaerobic oral flora (e.g., *Streptococcus viridans*, *Staphylococci*, and *Bacteroides*). While empiric broad-spectrum antibiotics (like Clindamycin or Penicillin + Metronidazole) are started immediately, **Culture and Sensitivity (C&S)** is the gold standard to identify the specific causative organisms and their susceptibility patterns. This allows for **de-escalation or targeted therapy**, ensuring the most effective antibiotic is used to prevent life-threatening complications like airway obstruction or mediastinitis. **2. Why Incorrect Options are Wrong:** * **Option A:** Severity is assessed clinically (airway status, systemic signs) and via imaging (CT scan), not by C&S. * **Option B:** Dosage is determined by pharmacokinetic properties and the severity of the infection, not by the sensitivity test itself. * **Option C:** C&S identifies the drug-pathogen match, which is its primary diagnostic purpose. * **Option D:** Discontinuation is based on clinical resolution of symptoms and inflammatory markers (CRP/WBC), not the initial C&S report. **Clinical Pearls for NEET-PG:** * **Most common cause:** Dental infection (usually 2nd or 3rd mandibular molars). * **Key Clinical Sign:** "Woody" or "Brawny" edema of the neck; the tongue is pushed up and back. * **Management Priority:** 1. Airway maintenance (most critical); 2. IV Antibiotics; 3. Incision and Drainage (if fluctuance or failed medical therapy). * **Danger:** It is a cellulitis, not an abscess, but can lead to rapid airway compromise.

Question 35: A cold abscess in the chest wall is most commonly associated with which of the following conditions?

A. Tuberculosis of the spine (Correct Answer)
B. Tuberculosis of the rib
C. Tuberculosis of the pelvis
D. Tuberculosis of the pleura

Explanation: ### Explanation **Correct Option: A. Tuberculosis of the spine** The term **"cold abscess"** refers to an abscess that lacks the traditional signs of acute inflammation (heat, redness, and pain), typically caused by *Mycobacterium tuberculosis*. In the context of the chest wall, the most common source is **Tuberculosis of the spine (Pott’s disease)**, specifically involving the thoracic vertebrae. The infection tracks from the vertebral bodies along the path of least resistance. The pus follows the **intercostal nerves and vessels**, traveling laterally and anteriorly within the neurovascular bundle to point on the chest wall. This is a classic example of a "wandering abscess." **Analysis of Incorrect Options:** * **B. Tuberculosis of the rib:** While TB of the rib can cause a localized chest wall abscess, it is statistically less common than spinal involvement tracking forward. * **C. Tuberculosis of the pelvis:** Pelvic TB (e.g., of the lumbar spine or sacroiliac joint) typically tracks downward along the psoas sheath to manifest as a **psoas abscess** in the groin or thigh, not the chest wall. * **D. Tuberculosis of the pleura:** Pleural TB usually results in pleural effusion or empyema necessitans (pus tracking through the chest wall), but it is a less frequent primary source for a classic "cold abscess" compared to the spine. **Clinical Pearls for NEET-PG:** * **Pott’s Paraplegia:** The most serious complication of spinal TB. * **Psoas Abscess:** Often originates from TB of the **T12–L5** vertebrae. * **Investigation of Choice:** MRI is the gold standard for visualizing spinal TB and soft tissue extensions. * **Treatment:** Multidrug Anti-Tubercular Therapy (ATT) is the mainstay; surgical drainage is reserved for neurological deficit or non-response to drugs.

Question 36: After incision and drainage of an abscess, the infectious process has failed to regress despite the patient being on high doses of an antibiotic. What would be the most appropriate next step?

A. Insert a large drain
B. Repeat culture and sensitivity tests (Correct Answer)
C. Debride and irrigate the area with a fibrinolytic agent
D. Begin the parenteral administration of proteolytic enzymes to augment the antibiotics

Explanation: ### Explanation The primary goal of treating an abscess is surgical decompression (Incision and Drainage) followed by appropriate antimicrobial therapy. When an infection fails to regress despite adequate drainage and high-dose antibiotics, it indicates a **treatment failure** likely due to an inappropriate antibiotic choice or the emergence of resistant organisms. **Why Option B is Correct:** The most logical next step is to **repeat culture and sensitivity tests**. This helps identify if the initial organism was misidentified, if a secondary infection (superinfection) has occurred, or if the pathogen has developed resistance to the current antibiotic regimen. Adjusting therapy based on updated sensitivity patterns is the standard of care for non-responsive surgical infections. **Analysis of Incorrect Options:** * **Option A:** Inserting a larger drain is unnecessary if the initial incision and drainage were performed correctly. If there is no new collection, a larger drain will not resolve a systemic or localized bacterial resistance issue. * **Option C:** Fibrinolytic agents (like streptokinase) are sometimes used in complex pleural empyema to break loculations, but they are not standard practice for general soft tissue abscesses and do not address the underlying cause of antibiotic failure. * **Option D:** Proteolytic enzymes have no proven clinical role in augmenting antibiotic efficacy in this context and are not part of standard surgical protocols. **Clinical Pearls for NEET-PG:** * **Source Control:** The most important step in managing any surgical infection is source control (drainage/debridement). * **Empiric vs. Targeted Therapy:** Always start with empiric antibiotics based on the suspected site, but switch to **targeted therapy** once culture results are available. * **Persistent Fever:** If a patient remains febrile after I&D, always rule out **undrained collections** (via USG/CT) or **antibiotic resistance**. * **Common Pathogen:** *Staphylococcus aureus* is the most common organism in cutaneous abscesses; consider MRSA in non-responsive cases.

Question 37: Elective cholecystectomy is classified as which type of surgical wound?

A. Clean
B. Dirty
C. Clean & contaminated (Correct Answer)
D. Contaminated

Explanation: **Explanation:** The classification of surgical wounds is based on the degree of microbial contamination at the time of surgery. This is a high-yield topic for NEET-PG as it predicts the risk of Surgical Site Infection (SSI). **Why "Clean-Contaminated" is correct:** A **Clean-Contaminated (Class II)** wound occurs when a hollow viscus (respiratory, alimentary, genital, or urinary tract) is entered under controlled conditions without unusual contamination. In an **elective cholecystectomy**, the surgeon intentionally enters the biliary tract (part of the alimentary system). Since the procedure is elective, there is no active infection (acute cholecystitis) or major break in technique, placing it squarely in Class II. **Analysis of Incorrect Options:** * **Clean (Class I):** These are uninfected operative wounds where no inflammation is encountered and the respiratory, alimentary, genital, or urinary tracts are **not** entered (e.g., Hernioplasty, Thyroidectomy). * **Contaminated (Class III):** These involve fresh, open accidental wounds, major breaks in sterile technique, or gross spillage from the GI tract. If a cholecystectomy involved "spillage of infected bile," it would be upgraded to this class. * **Dirty (Class IV):** These involve old traumatic wounds with retained devitalized tissue or existing clinical infection/perforation (e.g., perforated diverticulitis or a gallbladder abscess). **Clinical Pearls for NEET-PG:** 1. **SSI Risk:** Clean (<2%), Clean-contaminated (<10%), Contaminated (15-20%), Dirty (up to 40%). 2. **Prophylactic Antibiotics:** Usually indicated for Class II and III. For Class IV, the treatment is considered "therapeutic" rather than "prophylactic." 3. **Emergency Factor:** An elective cholecystectomy is Class II, but an emergency cholecystectomy for **acute cholecystitis** is often classified as **Contaminated (Class III)** due to active inflammation.

Question 38: What is the most common organism seen in peritonitis?

A. Escherichia coli (Correct Answer)
B. Clostridium welchii
C. Staphylococci
D. Klebsiella

Explanation: **Explanation:** Peritonitis is most commonly **secondary** to the perforation of a hollow viscus (e.g., peptic ulcer, appendix, or diverticulum). Since the gastrointestinal tract is a reservoir for a massive population of commensal bacteria, any breach in its integrity leads to a polymicrobial infection. **1. Why Escherichia coli is correct:** *Escherichia coli* (E. coli) is the most abundant facultative anaerobe in the colon. In cases of secondary peritonitis, it is the **most frequently isolated aerobic organism**. While peritonitis is typically polymicrobial (involving both aerobes and anaerobes like *Bacteroides fragilis*), E. coli remains the classic and most common answer in standardized examinations for the predominant causative agent. **2. Analysis of Incorrect Options:** * **Clostridium welchii (C. perfringens):** While found in the gut, it is an obligate anaerobe more commonly associated with gas gangrene or food poisoning rather than being the primary driver of general peritonitis. * **Staphylococci:** These are Gram-positive cocci primarily found on the skin. They are a common cause of **Primary Peritonitis** in patients undergoing Continuous Ambulatory Peritoneal Dialysis (CAPD), but not the most common in general surgical peritonitis. * **Klebsiella:** This is a common Gram-negative coliform that can cause peritonitis, but its prevalence is significantly lower than that of E. coli. **Clinical Pearls for NEET-PG:** * **Primary Peritonitis (SBP):** Most common organism in children is *Streptococcus pneumoniae*; in adults with cirrhosis, it is *E. coli*. * **Bacteroides fragilis:** The most common **anaerobe** isolated in secondary peritonitis. * **Synergistic Infection:** The pathophysiology of peritonitis involves a synergy where aerobes (E. coli) deplete oxygen, favoring the rapid growth of anaerobes. * **Treatment:** Empiric therapy must cover both Gram-negative rods and anaerobes (e.g., Cephalosporins + Metronidazole).

Question 39: What is the best treatment for gas gangrene?

A. Surgical debridement
B. Debridement with tetanus toxin
C. Debridement with IV penicillin (Correct Answer)
D. Debridement with polyvalent antitoxin

Explanation: **Explanation:** Gas gangrene (Clostridial Myonecrosis) is a life-threatening emergency caused primarily by *Clostridium perfringens*. The management strategy focuses on immediate surgical intervention and targeted antimicrobial therapy. **Why Option C is Correct:** The gold standard treatment for gas gangrene is **emergency surgical debridement combined with high-dose IV Penicillin G**. 1. **Surgical Debridement:** This is the most critical step. Since *Clostridia* are obligate anaerobes, removing necrotic tissue and exposing the area to oxygen stops toxin production and bacterial proliferation. 2. **IV Penicillin:** Penicillin G remains the drug of choice for *Clostridium*. Often, **Clindamycin** is added to the regimen because it inhibits bacterial protein synthesis, thereby suppressing the production of lethal exotoxins (Alpha and Theta toxins). **Why Other Options are Incorrect:** * **Option A:** While debridement is essential, it is insufficient as a standalone treatment. Systemic antibiotics are mandatory to control the spread of infection. * **Option B:** Tetanus toxoid/antitoxin is part of general wound management but does not treat the active myonecrosis caused by *C. perfringens*. * **Option D:** Polyvalent antitoxins against gas gangrene were used historically but are **no longer recommended** due to lack of proven efficacy and high risk of hypersensitivity reactions. **High-Yield Clinical Pearls for NEET-PG:** * **Incubation Period:** Very short (usually <24 hours). * **Clinical Sign:** "Dishwater pus" (thin, serosanguinous discharge) and **crepitus** (palpable gas in tissues). * **X-ray Finding:** Feathery pattern of gas in muscle planes. * **Hyperbaric Oxygen (HBO):** Often mentioned in exams; it is a useful **adjunct** but never a substitute for surgery. * **Most common organism:** *Clostridium perfringens* (Type A).

Question 40: Which of the following complications is not seen with peritonitis?

A. Renal Failure
B. Residual abscess
C. Endotoxic shock
D. Bone Marrow suppression (Correct Answer)

Explanation: **Explanation:** Peritonitis is a severe inflammatory response of the peritoneal cavity, usually resulting from bacterial infection or chemical irritation. It leads to a systemic inflammatory response syndrome (SIRS) and multi-organ dysfunction, but it does not typically cause bone marrow suppression. **Why Bone Marrow Suppression is the Correct Answer:** Bone marrow suppression is not a recognized complication of peritonitis. In fact, the physiological response to acute peritonitis is **leukocytosis** (an increase in white blood cell count), as the body attempts to fight the infection. While overwhelming sepsis can occasionally lead to "relative" neutropenia due to rapid consumption of neutrophils, the marrow itself remains active. Bone marrow suppression is more commonly associated with chemotherapy, radiation, or specific viral infections. **Analysis of Incorrect Options:** * **Renal Failure:** This is a common complication. Peritonitis causes significant "third-space" fluid loss and systemic vasodilation, leading to hypovolemia, decreased renal perfusion, and **Acute Tubular Necrosis (ATN)**. * **Residual Abscess:** Even after treatment, infected fluid can collect in dependent areas of the peritoneum (e.g., subphrenic space, Pelvis, or paracolic gutters), forming localized abscesses. * **Endotoxic Shock:** Gram-negative bacteria (common in gut perforation) release endotoxins (LPS), triggering a massive cytokine release. This leads to septic shock, characterized by hypotension and impaired tissue perfusion. **Clinical Pearls for NEET-PG:** * **Most common cause of primary peritonitis:** *Streptococcus pneumoniae* or *E. coli* (often seen in cirrhotic patients with ascites). * **Most common cause of secondary peritonitis:** Perforation of a hollow viscus (e.g., Peptic ulcer or Appendix). * **Radiology:** The presence of "pneumoperitoneum" (air under the diaphragm) on an erect X-ray is a classic sign of perforated viscus peritonitis. * **Management Priority:** Aggressive fluid resuscitation and source control (surgery) are the cornerstones of treatment.

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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