Surgical Infections — MCQs

Surgical Infections Indian Medical PG Practice Questions and MCQs

Question 161: What is the most common complication of a felon?

A. Osteomyelitis (Correct Answer)
B. Subungual hematoma
C. Infective arthritis
D. No complications

Explanation: ***Osteomyelitis*** - A **felon** is a severe infection of the **distal pulp space** of the fingertip, which has numerous fibrous septa. - The tightly compartmentalized nature of this space can lead to increased pressure, compromising blood supply and facilitating the spread of infection to the underlying **phalanx bone**, causing **osteomyelitis**. *Subungual hematoma* - A **subungual hematoma** is a collection of blood under the nail, usually resulting from direct trauma. - It is not a complication of an infection like a felon, but rather a separate traumatic injury. *Infective arthritis* - **Infective arthritis** involves the joint space, typically resulting from direct inoculation, hematogenous spread, or spread from adjacent soft tissue infection. - While possible, it is less common for a felon to directly spread to the **distal interphalangeal joint** compared to the more immediate risk of bone involvement. *No complications* - A **felon** is a serious infection that, if left untreated, almost always leads to complications due to the unique anatomy of the fingertip pulp space. - The high pressure within the compartments of the distal pulp makes it prone to necrosis and spread of infection to adjacent structures.

Question 162: Most common organism causing infection after an open fracture?

A. Klebsiella
B. Pseudomonas
C. Gonococcus
D. Staphylococcus aureus (Correct Answer)

Explanation: ***Staphylococcus aureus*** - *Staphylococcus aureus* is the **most common organism** causing infection in **open fractures**, accounting for 30-40% of cases. - It is present on **skin flora** and readily contaminates traumatic wounds, making it the predominant pathogen in the immediate post-injury period. - **Antibiotic prophylaxis** for open fractures (cephalosporins) primarily targets *S. aureus*, reflecting its clinical importance. - It causes both **early and late infections** in open fractures and is the leading cause of **post-traumatic osteomyelitis**. *Pseudomonas* - *Pseudomonas aeruginosa* can cause infections in open fractures but is **not the most common** organism. - More frequently seen in **Type III open fractures** with extensive soft tissue damage, **nosocomial infections**, or **delayed infections** after hospitalization. - Associated with **contaminated water exposure** and **chronic wounds** rather than being the primary pathogen in acute open fractures. *Klebsiella* - *Klebsiella* species are typically associated with **nosocomial infections**, particularly **urinary tract infections** and **pneumonia**. - Rarely the primary pathogen in acute open fracture infections. - May be seen in **hospital-acquired** infections in patients with prolonged hospitalization. *Gonococcus* - **Gonococcus** (*Neisseria gonorrhoeae*) is primarily associated with **sexually transmitted infections** and can cause **septic arthritis** through hematogenous spread. - It does **not** cause infections in open fractures as it is not found in the environment or on skin. - The mode of transmission is completely unrelated to trauma or wound contamination.

Question 163: Which of the following actions is NOT caused by hypochlorite?

A. Removing the smear layer
B. Providing lubrication (Correct Answer)
C. Causing bleaching
D. Flushing out debris

Explanation: ***Providing lubrication*** - Hypochlorite solutions primarily act as **antimicrobial agents** and **tissue dissolvers**, but they do not specifically provide lubrication. - While it aids in cleaning and debridement, it does not reduce friction or act as a lubricant in the way, for example, a gel might. *Causing bleaching* - Hypochlorite is well-known for its strong **oxidizing properties**, which enable it to break down chromophore molecules, leading to a bleaching effect. - In dentistry, this property is utilized for its ability to lighten tooth structure, although its primary role in root canal treatment is not bleaching but antimicrobial and tissue dissolving. *Removing the smear layer* - While hypochlorite dissolves organic components of the smear layer, it is **not sufficient to completely remove the inorganic components**. - **Chelating agents** like EDTA are typically used in conjunction with hypochlorite to effectively remove the entire smear layer. *Flushing out debris* - Hypochlorite solutions, particularly common root canal irrigants like sodium hypochlorite, are effective in **flushing out loose debris** from the root canal system due to their flow and bulk. - The **fluid dynamics** of irrigation help to carry away both organic and inorganic debris loosened by instrumentation and chemical action.

Question 164: Which of the following is the most common site for intra-abdominal abscesses?

A. Subphrenic
B. Pelvis (Correct Answer)
C. Paracolic
D. Retroperitoneal

Explanation: ***Pelvis*** - The **pelvis** is the most common site for intra-abdominal abscesses, particularly in ambulatory patients. - As the most gravity-dependent part of the peritoneal cavity, infected fluid naturally collects here. - **Pelvic abscesses** commonly result from appendicitis, diverticulitis, pelvic inflammatory disease, or postoperative complications. - Clinical features include pelvic pain, tenesmus, urinary symptoms, and fever. *Paracolic* - **Paracolic gutters** serve as pathways for fluid spread along the lateral aspects of the ascending and descending colon. - While infected fluid tracks through these gutters, it typically pools in dependent areas (pelvis or subphrenic spaces) rather than remaining in the gutters. - They are conduits rather than final collection sites. *Subphrenic* - **Subphrenic abscesses** occur beneath the diaphragm and are the second most common site. - Often associated with upper GI perforations, hepatobiliary surgery, or splenic procedures. - Present with shoulder tip pain, pleural effusion, and lower chest signs. *Retroperitoneal* - **Retroperitoneal abscesses** originate from retroperitoneal structures (kidneys, pancreas, psoas). - Less common than intraperitoneal abscesses. - Require CT imaging for diagnosis and often need percutaneous or surgical drainage.

Question 165: In the setting of contaminated fields in hernia, which mesh is used?

A. Biologic (Correct Answer)
B. Absorbable
C. Prosthetic
D. Composite

Explanation: ***Biologic*** - **Biologic meshes** are derived from animal or human tissue (e.g., acellular dermal matrix, porcine dermis) and are the **preferred choice for contaminated fields** (CDC Class III/IV wounds). - They resist infection better than synthetic materials, are gradually resorbed and remodeled by host tissue, and do not serve as a permanent foreign body that could harbor bacteria. - Studies show lower infection rates and mesh explantation rates in contaminated fields compared to synthetic alternatives. *Absorbable* - **Absorbable synthetic meshes** (e.g., polyglactin, poliglecaprone) are eventually resorbed but lack the infection resistance and tissue remodeling properties of biologic meshes. - They may be considered in selected contaminated cases but are inferior to biologics, offering only temporary support with higher failure rates. - Generally reserved for low-tension repairs or as temporary reinforcement. *Composite* - **Composite meshes** have dual layers with different properties (e.g., polypropylene on one side, ePTFE or absorbable barrier on the visceral side). - They are designed for intraperitoneal placement in clean cases but are **contraindicated in contaminated fields** due to high infection risk. - The synthetic components can serve as a nidus for bacterial colonization in contaminated settings. *Prosthetic* - **Prosthetic (non-absorbable synthetic) meshes** like polypropylene or polyester are **absolutely contraindicated in contaminated fields**. - They have the highest risk of infection, mesh-related complications, and often require explantation if infected. - Their permanent foreign body nature makes them incompatible with contaminated or infected surgical sites.

Question 166: Infection of the submandibular space is seen in:

A. Prinzmetal angina
B. Unstable angina
C. Ludwig angina (Correct Answer)
D. Vincent angina

Explanation: ***Ludwig angina*** - This is a rapidly progressive and potentially life-threatening **cellulitis** of the **submandibular, sublingual, and submental spaces**. - It typically originates from an **infected mandibular molar tooth** (most commonly the 2nd or 3rd molar). - Characterized by **bilateral** involvement, **brawny induration** of the neck, and potential for **airway compromise**. *Prinzmetal angina* - This is a type of **angina pectoris** characterized by chest pain due to **coronary artery spasm**, unrelated to infection. - It primarily affects the **heart** and does not involve the submandibular space. *Unstable angina* - This refers to **chest pain** or discomfort that occurs at rest or with minimal exertion, indicating a **pre-infarction state** due to coronary artery disease. - It is a cardiac condition and has no association with head and neck infections. *Vincent angina* - This condition is also known as **acute necrotizing ulcerative gingivitis (ANUG)** or trench mouth, a severe infection of the **gums and oral mucosa**. - While it is an infection of the oral cavity, it primarily affects the **gingiva** and does not involve the deep submandibular space in the same way as Ludwig angina.

Question 167: Kanavel's sign is seen in:

A. Mid palmar space abscess
B. Flexor tendon sheath infectious inflammation in the hand (Correct Answer)
C. Web space involvement
D. Ulnar bursa

Explanation: ***Flexor tendon sheath infectious inflammation in the hand*** - **Kanavel's signs** are a set of four clinical findings highly indicative of **flexor tenosynovitis** (infection of the flexor tendon sheath) in the hand. - These signs include **uniform swelling of the affected digit**, **flexed posturing of the affected digit**, **exquisite tenderness along the course of the flexor tendon sheath**, and **pain with passive extension of the affected digit**. *Mid palmar space abscess* - A **mid palmar space abscess** is a localized collection of pus in the central compartment of the hand and typically presents with **diffuse palmar swelling** and **tenderness**, not the specific findings of Kanavel's signs limited to a single digit. - While it can cause significant pain and restricted movement, it does not involve the flexor tendon sheath of a single digit in a way that elicits all four Kanavel's signs. *Ulnar bursa* - Inflammation/infection of the **ulnar bursa** (the common flexor sheath) can involve multiple digits, particularly the small finger and thumb if it communicates with the radial bursa, but the presentation is usually a more **diffuse swelling** of the palm and digits, not the isolated, characteristic signs of Kanavel's affecting a single digit. - Pain and swelling may be more generalized across the palm, and Kanavel's signs are specific to a single, infected flexor tendon sheath. *Web space involvement* - **Web space infections** occur in the loose connective tissue between the metacarpal heads in the interdigital spaces, presenting as **swelling** and **tenderness localized to the web space**. - This condition does not directly involve the flexor tendon sheath of a digit and therefore does not produce the specific clinical signs described by Kanavel.

Question 168: What is the best method of treatment for an ulnar nerve abscess in a case of leprosy?

A. High dose of clofazimine
B. Incision and drainage (Correct Answer)
C. Thalidomide
D. High doses of steroid

Explanation: ***Incision and drainage*** - An abscess, by definition, is a localized collection of **pus** that requires drainage for resolution and to prevent further tissue damage. - In the setting of an ulnar nerve abscess due to leprosy, surgical **incision and drainage** is the definitive treatment to remove the infected material and alleviate pressure on the nerve. *High doses of steroid* - Steroids are primarily used in leprosy to manage **nerve inflammation** and **reversal reactions**, not pre-formed pus collections like an abscess. - Using steroids alone for an abscess can suppress the immune response, potentially worsening the infection and delaying healing. *Thalidomide* - **Thalidomide** is most commonly used for severe type 2 leprosy reactions (**erythema nodosum leprosum**) due to its anti-inflammatory and immunomodulatory effects. - It does not have a role in directly treating a localized abscess, which requires physical drainage. *High dose of clofazimine* - **Clofazimine** is an anti-leprosy drug used as part of multi-drug therapy for treating the underlying *Mycobacterium leprae* infection. - While essential for treating leprosy, it will not resolve a pre-existing abscess, which is a collection of pus that needs to be mechanically drained.

Question 169: Infected gangrene of the skin and subcutaneous tissues is?

A. Gas gangrene (clostridial myonecrosis)
B. Erysipelas (a superficial bacterial skin infection)
C. Wet gangrene (necrosis with bacterial superinfection) (Correct Answer)
D. Dry gangrene (necrosis caused by ischemia without infection)

Explanation: ***Wet gangrene*** - Characterized by **infected gangrene**, where necrosis and infection occur in **skin and subcutaneous tissues**, typically presenting with foul-smelling discharge [1]. - Commonly associated with **venous insufficiency** and **bacterial infection**, leading to rapid progression and systemic symptoms [1]. *None of the above* - This option is incorrect as there are specific types of gangrene that are recognized in medical literature. - Saying "none of the above" does not accurately address the specific condition that is being asked about. *Dry gangrene* - Dry gangrene is typically caused by **ischemia** without significant infection, presenting with **dark, dry tissue**, and does not involve an infected state [1]. - It is mainly seen in conditions like **diabetes mellitus** and does not have the characteristic of **fluid accumulation** or infection that wet gangrene does [1]. *Erysipelas* - Erysipelas is a **superficial skin infection** caused by **Streptococcus**, presenting with redness and swelling, rather than necrosis of tissue. - It does not involve dead tissue as seen in gangrene, making it distinct and not a form of gangrene. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 103-104.

Question 170: Concentrated alcohol-based antiseptics for skin preparation of the operative site lead to

A. >95% reduction in bacterial count (Correct Answer)
B. >50% reduction in bacterial count
C. <50% reduction in bacterial count
D. Contraindicated for operative site

Explanation: ***>95% reduction in bacterial count*** - Concentrated **alcohol-based antiseptics**, particularly those containing concentrations like **70% isopropyl alcohol**, are highly effective in achieving a **significant log reduction** of bacterial flora on the skin. - This **high bactericidal activity** is crucial for minimizing surgical site infections by rapidly destroying bacterial cell membranes. * >50% reduction in bacterial count - While a >50% reduction is positive, it underestimates the actual efficacy of properly applied **concentrated alcohol-based antiseptics**. - These agents are known to provide a much more substantial and rapid reduction in **bacterial load** than just over half. * <50% reduction in bacterial count - This option is incorrect because **alcohol-based antiseptics** are well-established to provide a very high level of **skin decolonization** when used correctly. - A reduction of less than 50% would indicate a product with poor efficacy, which is contrary to the known properties of these solutions. * Contraindicated for operative site - This is incorrect; **alcohol-based antiseptics** are the **standard of care** for **surgical site preparation** due to their rapid and broad-spectrum antimicrobial activity. - They are contraindicated in specific situations (e.g., mucous membranes, open wounds, patients with alcohol sensitivity), but not for the general operative site.

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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