Surgical Infections — MCQs

Surgical Infections Indian Medical PG Practice Questions and MCQs

Question 41: Apart from Escherichia coli, what is the other most common organism implicated in acute suppurative bacterial peritonitis?

A. Bacteroides
B. Klebsiella (Correct Answer)
C. Peptostreptococcus
D. Pseudomonas

Explanation: **Explanation:** Acute suppurative bacterial peritonitis (Secondary Peritonitis) is typically a **polymicrobial infection** resulting from the perforation of a hollow viscus or inflammatory spread from intra-abdominal organs. **Why Klebsiella is correct:** In secondary peritonitis, the flora reflects the site of origin (usually the GI tract). While **Escherichia coli** is the most frequently isolated aerobic Gram-negative organism, **Klebsiella species** (specifically *K. pneumoniae*) rank as the second most common aerobic isolates. These organisms originate from the intestinal microbiota and proliferate rapidly in the peritoneal cavity following a breach in mucosal integrity. **Analysis of Incorrect Options:** * **A. Bacteroides:** While *Bacteroides fragilis* is the most common **anaerobe** isolated in peritonitis, it is generally found in combination with aerobes. In the context of "most common organisms" alongside E. coli, Klebsiella is statistically more frequent in aerobic cultures. * **C. Peptostreptococcus:** This is an anaerobic Gram-positive coccus. While present in polymicrobial intra-abdominal infections, it is less prevalent than E. coli or Klebsiella. * **D. Pseudomonas:** *Pseudomonas aeruginosa* is typically associated with tertiary peritonitis, immunocompromised states, or nosocomial (hospital-acquired) infections rather than primary or common secondary suppurative peritonitis. **High-Yield Clinical Pearls for NEET-PG:** * **Secondary Peritonitis:** Most common type; always polymicrobial (E. coli > Klebsiella > Streptococci > B. fragilis). * **Primary Peritonitis (SBP):** Usually monomicrobial; E. coli is the most common cause in adults with cirrhosis, while *Streptococcus pneumoniae* is common in children with nephrotic syndrome. * **Gold Standard Diagnosis:** Presence of free gas under the diaphragm on an erect X-ray (indicates perforation) and a peritoneal fluid WBC count >250 cells/mm³.

Question 42: Which of the following statements regarding gas gangrene is TRUE?

A. It is due to Clostridium botulinum infection.
B. Clostridial species are gram-negative spore-forming anaerobes.
C. The clinical features are due to the release of protein endotoxin.
D. Gas is invariably present in the muscle compartments. (Correct Answer)

Explanation: ### Explanation **Gas Gangrene (Clostridial Myonecrosis)** is a life-threatening necrotizing infection of the muscle. **Why Option D is Correct:** The hallmark of gas gangrene is the production of gas within the tissues as a byproduct of anaerobic fermentation of muscle carbohydrates. While gas may not always be visible on the skin surface early on, it is **invariably present within the muscle compartments** and fascial planes. This can be detected clinically as crepitus or radiologically as "feathering" of the muscle fibers on an X-ray. **Analysis of Incorrect Options:** * **Option A:** Gas gangrene is primarily caused by **_Clostridium perfringens_** (Type A), not _C. botulinum_ (which causes botulism/paralysis). * **Option B:** Clostridial species are **Gram-positive**, spore-forming, obligate anaerobic bacilli. * **Option C:** The systemic toxicity and tissue destruction are due to the release of **exotoxins**, most notably the **Alpha-toxin (Lecithinase)**, which dissolves cell membranes and causes massive hemolysis. Endotoxins are typically associated with Gram-negative bacteria. **NEET-PG High-Yield Pearls:** * **Incubation Period:** Very short, typically **6 to 48 hours** post-injury. * **Clinical Sign:** The earliest and most reliable symptom is **severe pain out of proportion** to physical findings, accompanied by a "mousy" or "sweetish" odor. * **Diagnosis:** Primarily clinical. Gram stain of wound discharge shows "Box-car" shaped Gram-positive bacilli with a characteristic **absence of polymorphonuclear leucocytes** (due to toxins lysing the WBCs). * **Treatment:** Emergency surgical debridement (fasciotomy/amputation), high-dose Penicillin G, and Hyperbaric Oxygen (HBO) therapy.

Question 43: Surgical complications of typhoid include all except?

A. Transverse intestinal ulcer (Correct Answer)
B. Intestinal perforation
C. Paralytic ileus
D. Intestinal hemorrhage

Explanation: **Explanation:** The correct answer is **A. Transverse intestinal ulcer**. In Typhoid fever (Enteric fever), the causative organism *Salmonella typhi* targets the **Peyer’s patches** located in the terminal ileum. Since Peyer’s patches are arranged **longitudinally** along the antimesenteric border, the resulting ulcers are also **longitudinal**. In contrast, **transverse ulcers** are characteristic of **Intestinal Tuberculosis**, where the infection spreads via circumferential lymphatics. **Analysis of Options:** * **Intestinal Perforation (B):** This is a classic surgical complication occurring typically in the **3rd week** of infection. It occurs when longitudinal ulcers erode through the serosa, usually in the terminal ileum. * **Paralytic Ileus (C):** This can occur due to severe toxemia or as a secondary response to localized/generalized peritonitis following a micro-perforation. * **Intestinal Hemorrhage (D):** Erosion of small blood vessels at the base of the sloughing Peyer’s patches leads to bleeding, usually during the **2nd or 3rd week**. **High-Yield Clinical Pearls for NEET-PG:** * **Site of Perforation:** Usually within the last **60 cm of the terminal ileum**. * **Pathology:** Typhoid ulcers follow the long axis of the bowel (Longitudinal); Tubercular ulcers follow the short axis (Transverse). * **Widal Test:** Becomes positive in the 2nd week. * **Drug of Choice:** Ceftriaxone is currently preferred for complicated typhoid; Ciprofloxacin was historically the DOC but resistance is now common. * **Surgical Management:** Primary closure (debridement and suturing) is the treatment of choice for perforations if the patient is stable and the perforation is seen early.

Question 44: Which of the following is a true statement about sepsis and septic shock?

A. It is the commonest cause of death in surgical patients. (Correct Answer)
B. The main treatment is addressing the infection site.
C. It leads to organ dysfunction.
D. Antibiotics have no role.

Explanation: **Explanation:** **Sepsis** is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. In the context of modern surgery, while surgical techniques and anesthesia have improved, sepsis remains the **leading cause of death in non-cardiac intensive care units (ICUs) and among surgical patients** worldwide. This is due to the high prevalence of healthcare-associated infections, complex comorbidities, and the emergence of multi-drug resistant organisms. **Analysis of Options:** * **Option A (Correct):** Epidemiological data consistently identifies sepsis and its progression to septic shock as the primary cause of mortality in surgical wards and ICUs. * **Option B (Incorrect):** While source control (addressing the infection site) is a cornerstone of management, the **mainstay of immediate treatment** in septic shock is aggressive fluid resuscitation and hemodynamic stabilization (the "Surviving Sepsis Campaign" bundles). Source control is vital but must occur alongside resuscitation. * **Option C (Incorrect):** This statement is technically true according to the Sepsis-3 definition; however, in the context of this specific multiple-choice question format, Option A is the "most correct" epidemiological fact frequently tested in NEET-PG. * **Option D (Incorrect):** Antibiotics are critical. Early administration of broad-spectrum antibiotics (ideally within the first hour) is proven to reduce mortality significantly. **High-Yield Clinical Pearls for NEET-PG:** * **Sepsis-3 Definition:** Sepsis = Infection + SOFA score ≥ 2 points. * **Septic Shock:** Sepsis requiring vasopressors to maintain MAP ≥ 65 mmHg AND serum lactate > 2 mmol/L despite adequate fluid resuscitation. * **qSOFA (Quick SOFA):** Includes Respiratory rate ≥ 22/min, Altered mentation (GCS < 15), and Systolic BP ≤ 100 mmHg. * **Warm Shock:** Early septic shock often presents with peripheral vasodilation (decreased SVR) and high cardiac output, leading to warm, flushed skin.

Question 45: Which of the following is not a stage of progression of space infection?

A. Inoculation
B. Abscess
C. Cellulitis
D. Isolation (Correct Answer)

Explanation: **Explanation:** The progression of a surgical space infection (particularly odontogenic or soft tissue infections) follows a predictable clinical timeline based on the host-pathogen interaction. The stages represent the evolution from initial bacterial entry to localized suppuration. **Why "Isolation" is the correct answer:** In the context of surgical infections, **Isolation** is not a recognized stage of progression. While the body attempts to "isolate" an infection via a pyogenic membrane or fibrin wall during the abscess stage, "Isolation" itself is not a formal term used to describe the chronological stages of infection spread. **Analysis of Incorrect Options (The actual stages):** * **Inoculation (0–3 days):** This is the initial stage where bacteria are introduced into the space. It is characterized by soft, mildly tender, and diffuse swelling. Aerobic bacteria predominate here. * **Cellulitis (2–5 days):** As the infection spreads, the area becomes hard (indurated), red, and intensely painful. This is an inflammatory response to the rapid multiplication of both aerobic and anaerobic bacteria. There is no pus at this stage. * **Abscess (4–10 days):** This is the final stage of progression where the center of the infection liquefies. Anaerobes predominate, and clinical signs include **fluctuation** and localized pus formation. **NEET-PG High-Yield Pearls:** * **Sequence:** Inoculation $\rightarrow$ Cellulitis $\rightarrow$ Abscess $\rightarrow$ Resolution/Rupture. * **Cellulitis vs. Abscess:** Cellulitis is diffuse, painful, and lacks fluctuation; an Abscess is localized, less painful than cellulitis, and shows **fluctuation**. * **Microbiology:** Cellulitis is often driven by *Streptococci* (hyaluronidase production helps spread), while Abscesses are often driven by *Staphylococci* or anaerobes. * **Treatment:** Cellulitis is primarily managed with antibiotics; an Abscess requires **Incision and Drainage (I&D)**.

Question 46: Hilton's method of treatment of an axillary abscess is advised because it:

A. Protects vital structures (Correct Answer)
B. Ensures adequate drainage
C. Hinders the spread of infection
D. Allows local instillation of antibiotics

Explanation: **Explanation:** **Hilton’s Method** is a specialized surgical technique used to drain deep-seated abscesses located in anatomical areas containing vital neurovascular structures (e.g., the axilla, groin, or submandibular region). **1. Why Option A is Correct:** The primary objective of Hilton’s method is to **protect vital structures** (nerves and major blood vessels). In the axilla, the axillary artery, vein, and brachial plexus are at high risk of injury if a sharp scalpel is used deep within the tissue. The technique involves: * Making a superficial skin incision with a scalpel. * Using a **blunt hemostat (sinus forcep)** to pierce the deep fascia and enter the abscess cavity. * Opening the forceps within the cavity and withdrawing them open to enlarge the track. This blunt dissection ensures that vessels and nerves are pushed aside rather than transected. **2. Why Other Options are Incorrect:** * **Option B:** While the method does facilitate drainage, "adequate drainage" can be achieved by many techniques. The *specific* reason for choosing Hilton’s over a standard wide incision is safety, not the volume of drainage. * **Option C:** Hilton’s method does not inherently possess antimicrobial properties to hinder the spread of infection more than any other drainage procedure. * **Option D:** Local instillation of antibiotics is not a standard part of this surgical maneuver and is generally discouraged in favor of systemic therapy and source control. **Clinical Pearls for NEET-PG:** * **Indications:** Axillary abscess, Groin abscess (near femoral vessels), and Ludwig’s Angina (submandibular space). * **Instrument used:** Sinus forceps or Hemostat. * **Key Step:** Always incise the skin **parallel to the skin creases** (Langer’s lines) for better healing, but use blunt dissection for the deep layers.

Question 47: Which of the following are common causes of non-surgical infections in a surgical patient?

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

Explanation: In surgical patients, infections are broadly categorized into **Surgical Site Infections (SSIs)** and **Non-Surgical Infections (Nosocomial/Healthcare-associated infections)**. ### **Explanation of the Correct Answer** **Option C** is correct because it lists infections that occur as a consequence of the hospital environment, immobilization, or antibiotic use, rather than the surgical incision itself: 1. **Lower Respiratory Tract Infection (LRTI):** Often manifests as basal atelectasis or hospital-acquired pneumonia due to anesthesia-induced lung collapse, poor cough reflex, and prolonged recumbency. 2. **Urinary Tract Infection (UTI):** The most common nosocomial infection, usually secondary to indwelling urinary catheters (CAUTI). 3. **Clostridium difficile Diarrhea:** A common complication of perioperative prophylactic or therapeutic broad-spectrum antibiotic use, which disrupts normal gut flora. ### **Analysis of Incorrect Options** * **Options A, B, and D:** These are incorrect because they either omit one of the three major non-surgical causes or include **Wound Infection**. A wound infection is, by definition, a **Surgical Site Infection (SSI)**, as it occurs at the site of the operative procedure. ### **NEET-PG High-Yield Pearls** * **Most Common Nosocomial Infection:** UTI (usually due to *E. coli*). * **Most Common Cause of Post-operative Fever (Day 1-2):** Atelectasis (leading to LRTI). * **C. difficile Management:** The first step is to stop the offending antibiotic. The drug of choice is oral Vancomycin or Fidaxomicin. * **SSI Timing:** Typically occurs within 30 days of surgery (or up to 1 year if a prosthetic implant is used). * **The "5 W’s" of Post-op Fever:** **W**ind (Atelectasis/Pneumonia), **W**ater (UTI), **W**ound (SSI), **W**alking (DVT/PE), and **W**onder drugs (Drug fever).

Question 48: What is the term for infective gangrene of the subcutaneous tissue that often occurs in the nape of the neck?

A. Boil
B. Furuncle
C. Carbuncle (Correct Answer)
D. Impetigo

Explanation: **Explanation:** The correct answer is **Carbuncle**. A carbuncle is an infective gangrene of the subcutaneous tissue caused by *Staphylococcus aureus*. It typically occurs in areas where the skin is thick and inelastic, such as the **nape of the neck** or the back. The infection spreads horizontally in the subcutaneous fat, limited by vertical fibrous septa, leading to multiple points of suppuration (the classic **"sieve-like"** or **"cribriform"** appearance). **Analysis of Options:** * **Boil/Furuncle (Options A & B):** These terms are synonymous. A furuncle is an acute staphylococcal infection of a single hair follicle and its associated sebaceous gland. It is more superficial and localized compared to a carbuncle. * **Impetigo (Option D):** This is a highly contagious, superficial skin infection (epidermal layer) characterized by honey-colored crusting, usually caused by *Streptococcus pyogenes* or *S. aureus*. It does not involve subcutaneous gangrene. **High-Yield Clinical Pearls for NEET-PG:** * **Predisposing Factor:** **Diabetes Mellitus** is the most common underlying condition. Always check urine sugar or HbA1c in a patient with a carbuncle. * **Pathognomonic Sign:** The **cribriform appearance** (multiple discharging sinuses). * **Treatment:** While small carbuncles may respond to antibiotics, the definitive treatment for a mature carbuncle is **cruciate incision and debridement** of all necrotic subcutaneous tissue. * **Common Site:** Nape of the neck and shoulders (due to friction and thick skin).

Question 49: Gas in the tissue should be differentiated with which of the following?

A. Pseudomyxoma peritonei
B. Pseudomonas infection
C. Clostridium species infection (Correct Answer)
D. Non-clostridial infection

Explanation: **Explanation:** Gas in the tissues (crepitus) is a hallmark of certain necrotizing soft tissue infections. While the question asks what it should be differentiated with, it highlights the classic association between **Clostridium species** (specifically *C. perfringens*) and gas gangrene (Clostridial Myonecrosis). **Why Option C is correct:** Clostridial infections are the prototypical cause of gas in the tissue. These anaerobic, spore-forming bacilli produce alpha-toxins that cause tissue necrosis and ferment carbohydrates, leading to the production of insoluble gas (hydrogen and carbon dioxide) that accumulates in tissue planes. **Analysis of Incorrect Options:** * **A. Pseudomyxoma peritonei:** This is a clinical condition characterized by the accumulation of gelatinous (mucinous) ascites in the peritoneal cavity, typically originating from an appendiceal or ovarian mucinous tumor. It does not involve gas production. * **B. Pseudomonas infection:** While *Pseudomonas aeruginosa* can cause severe skin infections (like Ecthyma gangrenosum in immunocompromised patients), it is not a primary gas-forming organism. It is more classically associated with "blue-green" pus due to pyocyanin pigment. * **D. Non-clostridial infection:** While non-clostridial organisms (like *E. coli*, *Klebsiella*, or anaerobic streptococci) *can* produce gas (Non-clostridial Crepitant Cellulitis), the question focuses on the most definitive and classic differentiation required in a surgical context—identifying the life-threatening Clostridial species. **High-Yield Clinical Pearls for NEET-PG:** * **Imaging:** X-ray is the fastest way to detect "feathering" or gas patterns in muscle planes. * **Diagnosis:** Gas gangrene is a **clinical diagnosis**. The presence of gas is a late sign; the earliest sign is often pain out of proportion to physical findings. * **Management:** Immediate surgical debridement is the gold standard. Penicillin G and Clindamycin (to suppress toxin production) are the antibiotics of choice. * **Hyperbaric Oxygen (HBO):** Often used as an adjunct to stop toxin production in Clostridial infections.

Question 50: All of the following statements about Necrotizing fasciitis are true, except?

A. Infection of fascia and subcutaneous tissue
B. Most commonly caused by Group A beta hemolytic streptococci
C. Most common site is perineum followed by trunk and extremities (Correct Answer)
D. Surgical debridement is mandatory

Explanation: ### Explanation **Necrotizing Fasciitis (NF)** is a life-threatening, rapidly progressive infection of the deep fascia and subcutaneous tissues, characterized by extensive necrosis and systemic toxicity. **1. Why Option C is the Correct Answer (The False Statement):** While the perineum is a classic site (known as **Fournier’s Gangrene**), it is **not** the most common site overall. Statistically, the **extremities** (especially the lower limbs) are the most common site of involvement, followed by the perineum and the trunk. Therefore, the sequence mentioned in the option is incorrect. **2. Analysis of Incorrect Options (True Statements):** * **Option A:** NF is defined by the widespread necrosis of the **fascia and subcutaneous fat**, while initially sparing the overlying skin and underlying muscle (until late stages). * **Option B:** While NF is often polymicrobial (Type I), **Group A beta-hemolytic Streptococcus (S. pyogenes)** is the most common monomicrobial cause (Type II), often referred to as the "flesh-eating bacteria." * **Option D:** NF is a surgical emergency. Medical management alone is insufficient; **aggressive, early surgical debridement** of all necrotic tissue is mandatory to control the source of infection and reduce mortality. **3. Clinical Pearls for NEET-PG:** * **LRINEC Score:** Used to differentiate NF from other soft tissue infections (based on CRP, WBC, Hemoglobin, Sodium, Creatinine, and Glucose). A score ≥ 6 suggests NF. * **Clinical Sign:** "Pain out of proportion" to the physical findings is the earliest hallmark. * **Hard Signs:** Crepitus, skin anesthesia, and bullae/purple skin discoloration indicate advanced disease. * **Imaging:** X-ray or CT may show **gas in the soft tissues** (pathognomonic for Type I/clostridial infections). * **Treatment:** Triple antibiotics (usually Penicillin, Clindamycin, and an Aminoglycoside/Carbapenem) + Emergency Debridement.

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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