Surgical Infections Practice Questions

Q: Drug of choice for surgical prophylaxis?

Cefazolin. ***Cefazolin*** - **Cefazolin** is a first-generation cephalosporin that provides excellent coverage against **Staphylococcus aureus** and **coagulase-negative staphylococci**, which are common surgical site pathogens. - Its **longer half-life** allows for less frequent dosing and it achieves good tissue penetration, making it ideal for surgical prophylaxis. *Cefaclor* - **Cefaclor** is a second-generation cephalosporin with a broader spectrum of activity but a **shorter half-life**, which makes it less suitable for sustained prophylactic levels. - It offers good oral bioavailability but is generally **not preferred for intravenous surgical prophylaxis** compared to cefazolin. *Ceftizoxime* - **Ceftizoxime** is a third-generation cephalosporin with **broader gram-negative coverage** than cefazolin, but this is often not necessary for routine surgical prophylaxis. - Its spectrum includes organisms less commonly implicated in surgical site infections, and its use could **contribute to antibiotic resistance** without added benefit. *Cefoperazone* - **Cefoperazone** is a third-generation cephalosporin with good activity against **Pseudomonas aeruginosa** and gram-negative bacteria, often used for more serious or nosocomial infections. - Its **broader spectrum** and higher cost make it less appropriate for standard surgical prophylaxis, where a narrower-spectrum agent like cefazolin is effective and preferred.

Q: Infection of flexor tendon sheath involving the ulnar bursa is diagnosed by?

Kanavel's sign. ***Kanavel's sign*** - **Kanavel's signs** are a set of four clinical findings highly suggestive of **flexor tenosynovitis**, particularly when involving the ulnar bursa, which forms a continuous sheath with the flexor tendons of the small, ring, and middle fingers. - These signs include **uniform swelling of the digit**, **fixed flexion posture of the digit**, **tenderness along the flexor tendon sheath**, and **pain on passive extension of the digit**. *Chowstek's sign* - **Chvostek's sign** is a clinical finding associated with **hypocalcemia**, characterized by a twitching of the facial muscles in response to tapping over the facial nerve. - It is not related to infections of the hand or flexor tendon sheaths. *Gower's sign* - **Gower's sign** is observed in individuals with **proximal muscle weakness**, particularly in muscular dystrophies. - It describes the characteristic way a patient "climbs up" their legs to stand from a seated position due to weakened hip and thigh muscles. *Ludloff's sign* - **Ludloff's sign** is a diagnostic indicator for an **avulsion fracture of the lesser trochanter** of the femur. - It involves pain felt in the groin and buttock area when the patient attempts to lift an extended leg from a seated position.

Q: A diabetic patient presents with sudden-onset perineal pain. On examination, foul-smelling discharge and necrotic tissue are noted. Which of the following is the most characteristic feature of this condition?

Mixed aerobic and anaerobic infection. **Mixed aerobic and anaerobic infection** - Fournier's gangrene is a polymicrobial infection typically involving a **synergistic mixture of aerobic and anaerobic bacteria**. - This mixed infection contributes to the rapid progression and tissue destruction seen in this condition, leading to the **foul-smelling discharge** due to anaerobic metabolism. *Anti-gas gangrene serum is indicated only in specific cases.* - Anti-gas gangrene serum is specifically for **Clostridium perfringens** infections, which can cause gas gangrene but is usually a distinct clinical entity from Fournier's. - While Clostridium species can be present in Fournier's gangrene, it is not the sole causative agent, and **broader antimicrobial therapy** is the mainstay of treatment, not antitoxin serum. *Urinary diversion may be considered in severe cases.* - Urinary diversion, such as a **suprapubic catheter**, may be necessary when the urethra or perineum is extensively involved or to prevent ongoing contamination of the surgical site. - However, it's not a primary treatment for the infection itself but rather an **adjunctive measure** to manage complicated cases of Fournier's gangrene. *Bilateral orchidectomy is not routinely required.* - **Testicular involvement** in Fournier's gangrene is rare due to the separate blood supply of the testes. - **Orchidectomy** is only performed if the testes themselves are affected by necrosis, which is uncommon and occurs in critically severe cases; routine removal is not indicated.

Q: Which of the following is the drug of choice for preoperative antibiotic prophylaxis in a patient undergoing cardiac surgery?

Cefazolin. ***Cefazolin*** - **Cefazolin** is a first-generation cephalosporin that provides excellent coverage against **Staphylococcus aureus** and **Streptococcus species**, which are common pathogens in surgical site infections in cardiac surgery. - It has a favorable safety profile, long half-life allowing for convenient dosing, and good tissue penetration, making it the preferred choice for **preoperative antibiotic prophylaxis** in most cardiac surgery cases. *Penicillin* - **Penicillin** has a narrow spectrum of activity compared to cefazolin and does not adequately cover all potential pathogens in cardiac surgery, particularly **methicillin-susceptible Staphylococcus aureus (MSSA)**. - Due to its limited spectrum, penicillin is generally not recommended for routine **surgical prophylaxis**, especially in complex procedures like cardiac surgery. *Clindamycin* - **Clindamycin** is an alternative for patients with **beta-lactam allergies**, providing coverage against gram-positive organisms and anaerobes. - However, for routine prophylaxis without a specific allergy or high risk of resistant organisms, **clindamycin** is less effective than cefazolin against the most prevalent surgical pathogens. *Vancomycin* - **Vancomycin** is reserved for patients with a known **penicillin allergy** or a high risk of **methicillin-resistant Staphylococcus aureus (MRSA)** colonization or infection. - Its routine use as a primary prophylactic agent in cardiac surgery is discouraged to prevent the development of **vancomycin resistance**.

Q: Identify the most common site of an intraperitoneal abscess.

Pelvis (Pouch of Douglas). ***Pelvis (Pouch of Douglas)*** - The **Pouch of Douglas** (rectouterine or rectovesical pouch) is the **most common site** for intraperitoneal abscesses. - It is the **most dependent (lowest) part** of the peritoneal cavity in both upright and supine positions, allowing gravity to facilitate collection of infected fluid. - Commonly results from **perforated appendicitis**, **diverticulitis**, **gynecological infections** (PID, tubo-ovarian abscess), or any source of peritoneal contamination where infected material flows downward. - **Clinical significance**: Pelvic abscesses can be drained via transrectal or transvaginal approaches, making them accessible for percutaneous drainage. *Subhepatic* - The **subhepatic space** (Morison's pouch on the right) is a **common but not the most common** site for intraperitoneal abscesses. - More specifically associated with **cholecystitis**, **perforated duodenal ulcers**, or hepatobiliary surgery complications. - While dependent in the supine position, it is less dependent than the pelvis in the upright position. *Suprahepatic* - Abscesses in the **suprahepatic space** are relatively uncommon. - May occur from direct extension of liver abscesses or as complications of upper abdominal surgery. - The presence of peritoneal attachments limits widespread fluid collection in this area. *Left subphrenic space* - The **left subphrenic space** is less commonly involved than the pelvis or right subphrenic spaces. - Typically arises from complications of **splenic injury**, **pancreatitis**, **gastric perforations**, or post-splenectomy infections.

Q: A person reports 4 hours after having a clean wound without laceration. He had taken TT 10 years before. The next step in management is:

Single-dose TT. ***Single-dose TT*** - For a **clean wound** when the last **tetanus toxoid (TT)** was given **10 years ago**, a **booster dose** is indicated as the protective immunity duration is **10 years**. - **TT provides immunity for 10 years** for clean wounds; at the 10-year mark, the protective window has elapsed and requires a booster. *No need for any vaccine* - This would be correct only if the last TT dose was given **<10 years ago** (within the protective window). - At exactly **10 years**, the immunity has waned and a **booster is required** for continued protection against tetanus. *Full course Tetanus vaccine to be given* - A **complete primary series (3 doses)** is only indicated for patients who are **unimmunized** or have **unknown vaccination history**. - This patient has documented **prior TT immunization**, so only a **single booster dose** is needed, not a full course. *Full dose TT with TIG* - **Tetanus Immunoglobulin (TIG)** is reserved for **high-risk scenarios**: tetanus-prone wounds in patients with **inadequate immunization** (<3 doses) or **unknown vaccination status**. - For a **clean wound** with documented prior immunization, **TIG is unnecessary** and represents over-treatment.

Q: What is the best management for a human bite?

Ampicillin plus sulbactam. ***Ampicillin plus sulbactam*** - This combination is effective against the common **aerobic and anaerobic bacteria** found in human bite wounds, including **Eikenella corrodens** and oral streptococci. - The sulbactam component provides **beta-lactamase inhibition**, which is crucial as many oral bacteria produce these enzymes, rendering ampicillin alone ineffective. *Clindamycin plus TMP-SMX* - While clindamycin covers many anaerobes, it has **poor activity against Eikenella corrodens**, a key pathogen in human bites. - **TMP-SMX (trimethoprim-sulfamethoxazole)** also lacks reliable coverage against many oral anaerobes and Eikenella. *Fluoroquinolone* - **Fluoroquinolones** generally have good Gram-negative coverage but often possess **limited activity against oral anaerobes and streptococci** relevant to human bites. - There is a **growing concern for resistance** with fluoroquinolone monotherapy in these types of infections. *Doxycycline* - Doxycycline has a broad spectrum but is **not the first-line choice for human bites** due to inconsistent activity against common oral anaerobes and Eikenella corrodens. - It may be considered in specific cases, but **empiric coverage needs to be broader** for initial management of these **polymicrobial infections**.

Q: What is the optimal timing for administering antibiotic prophylaxis before surgery?

30-60 minutes before incision. ***30-60 minutes before incision*** - This is the **optimal timing** recommended by WHO, CDC, and major surgical guidelines for most commonly used prophylactic antibiotics (cefazolin, cefuroxime). - Ensures **peak tissue and serum concentrations** are achieved at the time of incision, providing maximum protection against surgical site infections. - Based on **pharmacokinetic principles**: the antibiotic must be present at bactericidal concentrations in tissues when bacterial contamination occurs. - Studies show this timing significantly reduces surgical site infection rates compared to other timings. *Immediately before induction of anesthesia* - While acceptable in some protocols, this may be too early if there is a delay between induction and incision. - Could result in **declining antibiotic levels** by the time the incision is made, especially for antibiotics with shorter half-lives. *2-3 hours before surgery* - This is **too early** for most antibiotics. - Tissue levels may have already **declined below therapeutic concentrations** by the time of incision. - Does not provide adequate protection during the critical period of bacterial contamination. *Immediately after surgery* - This is **treatment, not prophylaxis**. - Offers **no preventive benefit** against intraoperative contamination. - By this time, bacteria introduced during surgery have already adhered to tissues and begun forming biofilms.

Q: Most common organism involved in surgical site infections -

Staphylococcus aureus. ***Staphylococcus aureus*** - **Staphylococcus aureus** is a common commensal on human skin and mucous membranes, making it readily available to contaminate surgical wounds. - It produces various **virulence factors** that aid in adhesion, invasion, and evasion of host defenses, contributing to its high infectivity in surgical sites. - It is the **most common cause** of surgical site infections across all surgical specialties, accounting for 20-30% of all SSIs. *E. coli* - **Escherichia coli** is primarily associated with **gastrointestinal and urinary tract infections**, and is the second most common cause of SSIs (especially after GI/GU surgeries). - While it can cause infections, it's not the most frequent causative agent across all types of surgical procedures. *Legionella* - **Legionella species** are known to cause **Legionnaires' disease**, a severe form of pneumonia, and are typically acquired from contaminated water sources. - It is an **extremely rare cause** of surgical site infections and is not considered a primary pathogen in this context. *Streptococcus pneumoniae* - **Streptococcus pneumoniae** is a leading cause of **pneumonia, meningitis, and otitis media**. - While it can cause opportunistic infections, it is not a common cause of surgical site infections.

Question 1

Which of the following statements is true regarding the spread of infection in tenosynovitis of the finger?

Accepted Answer

In tenosynovitis, the infection of the little finger can spread to the thumb.

Answer

The treatment for tenosynovitis is primarily surgical.

Answer

Fingers affected by tenosynovitis are typically held in extension to prevent spread of infection.

Answer

Involvement of the little finger does not lead to infection spreading to the index finger, as they have separate synovial sheaths.

Question 2

Drug of choice for surgical prophylaxis?

Accepted Answer

Cefazolin

Answer

Cefaclor

Answer

Ceftizoxime

Answer

Cefoperazone

Question 3

Infection of flexor tendon sheath involving the ulnar bursa is diagnosed by?

Accepted Answer

Kanavel's sign

Answer

Gower's sign

Answer

Ludloff's sign

Answer

Chvostek's sign

Question 4

A diabetic patient presents with sudden-onset perineal pain. On examination, foul-smelling discharge and necrotic tissue are noted. Which of the following is the most characteristic feature of this condition?

Accepted Answer

Mixed aerobic and anaerobic infection

Answer

Urinary diversion may be considered in severe cases

Answer

Bilateral orchidectomy is not routinely required

Answer

Anti-gas gangrene serum is indicated only in specific cases

Question 5

Which of the following is the drug of choice for preoperative antibiotic prophylaxis in a patient undergoing cardiac surgery?

Accepted Answer

Cefazolin

Answer

Penicillin

Answer

Clindamycin

Answer

Vancomycin

Question 6

Identify the most common site of an intraperitoneal abscess.

Accepted Answer

Pelvis (Pouch of Douglas)

Answer

Suprahepatic

Answer

Left subphrenic space

Answer

Subhepatic

Question 7

A person reports 4 hours after having a clean wound without laceration. He had taken TT 10 years before. The next step in management is:

Accepted Answer

Single-dose TT

Answer

No need for any vaccine

Answer

Full course Tetanus vaccine to be given

Answer

Full dose TT with TIG

Question 8

What is the best management for a human bite?

Accepted Answer

Ampicillin plus sulbactam

Answer

Clindamycin plus TMP-SMX

Answer

Fluoroquinolone

Answer

Doxycycline

Question 9

What is the optimal timing for administering antibiotic prophylaxis before surgery?

Accepted Answer

30-60 minutes before incision

Answer

Immediately before induction of anesthesia

Answer

2-3 hours before surgery

Answer

Immediately after surgery

Question 10

Most common organism involved in surgical site infections -

Accepted Answer

Staphylococcus aureus

Answer

E. coli

Answer

Legionella

Answer

Streptococcus pneumoniae

Surgical Infections — MCQs

Surgical Infections — MCQs

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