Antimicrobial Therapy in Surgical Infections — MCQs

10 questions

A patient with a non-obstructing carcinoma of the sigmoid colon is being prepared for elective resection. To minimize the risk of postoperative infectious complications, what should be included in your planning?

Empirical drug of choice for treatment of meningococcal meningitis is:-

Which of the following drugs need not be stopped before surgery?

A patient presents to the emergency room with vomiting, diarrhea, high fever, and delirium. Upon physical examination, you notice large buboes, which are painful on palpation, and purpura and ecchymoses suggestive of disseminated intravascular coagulation. Gram stain on aspirate of a bubo reveals gram-negative rods with bipolar staining. Which of the following antibiotics is the drug of choice for empiric therapy?

Drugs of choice for MRSA in skin and soft tissue infections are:

Preferred time for prophylactic antibiotic administration for surgery?

What is the most appropriate treatment for a patient with a suspected Brodie's abscess?

A 60M diabetic presents with severe ear pain, otorrhea, and facial nerve palsy. CT reveals bony erosion of the temporal bone. His glucose level is 350 mg/dL. Most appropriate management?

Which of the following is true about tenosynovitis of the finger?

Q10

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?

Antimicrobial Therapy in Surgical Infections Indian Medical PG Practice Questions and MCQs

Question 1: A patient with a non-obstructing carcinoma of the sigmoid colon is being prepared for elective resection. To minimize the risk of postoperative infectious complications, what should be included in your planning?

A. Postoperative administration for 5 to 7 days of parenteral antibiotics effective against aerobes and anaerobes
B. A single preoperative parenteral dose of antibiotic effective against aerobes and anaerobes may provide initial coverage. (Correct Answer)
C. Postoperative administration for 2 to 4 days of parenteral antibiotics effective against aerobes and anaerobes
D. Avoidance of oral antibiotics to prevent emergence of Clostridioides difficile

Explanation: ***Single preoperative parenteral dose of antibiotic effective against aerobes and anaerobes*** - For **elective colorectal surgery**, a single dose of a **broad-spectrum parenteral antibiotic** administered within 60 minutes prior to incision is the standard of care to reduce surgical site infections. - This approach ensures adequate drug levels in the tissues during the period of potential bacterial contamination and is a cornerstone of modern surgical prophylaxis. - Current guidelines (WHO, SCIP) recommend a single preoperative dose, which may be redosed intraoperatively if the procedure is prolonged beyond 3-4 hours. *Avoidance of oral antibiotics to prevent emergence of Clostridioides difficile* - This is **incorrect**. **Oral antibiotics** (such as neomycin and metronidazole) are routinely used preoperatively in conjunction with mechanical bowel preparation for colorectal surgery to reduce intraluminal bacterial load. - The concern for *Clostridioides difficile* infection is generally low with short-term, targeted prophylactic antibiotic regimens compared to broad-spectrum, prolonged use. - The combination of oral and parenteral antibiotics has been shown to further reduce surgical site infections. *Postoperative administration for 5 to 7 days of parenteral antibiotics* - **Prolonged postoperative antibiotic administration** beyond 24 hours in uncomplicated cases is not recommended as it increases the risk of **antibiotic resistance**, *C. difficile* infection, and adverse drug reactions without additional benefit. - The goal of prophylactic antibiotics is to cover the period of contamination during surgery, not to treat presumed ongoing infection postoperatively. *Postoperative administration for 2 to 4 days of parenteral antibiotics* - While administration for up to 24 hours post-operatively may be considered in some high-risk cases, routine **prolonged postoperative antibiotics** (2-4 days) are unnecessary for most elective colorectal resections. - Evidence suggests that continuing antibiotics beyond the immediate perioperative period does not further reduce the incidence of **surgical site infections** in clean-contaminated surgeries.

Question 2: Empirical drug of choice for treatment of meningococcal meningitis is:-

A. Cefotetan
B. Cefoxitin
C. Gentamicin
D. Ceftriaxone (Correct Answer)

Explanation: ***Ceftriaxone*** - As a **third-generation cephalosporin**, **Ceftriaxone** provides excellent coverage against common bacterial causes of meningitis, including *Neisseria meningitidis*. - It achieves high concentrations in the **cerebrospinal fluid (CSF)**, making it highly effective for CNS infections. *Cefotetan* - **Cefotetan** is a **second-generation cephalosporin** that has limited CSF penetration and less reliable coverage against common meningitis pathogens. - While it has activity against some gram-negative bacteria, it is not considered a first-line agent for empirical treatment of meningitis. *Cefoxitin* - **Cefoxitin** is also a **second-generation cephalosporin** with limited ability to cross the blood-brain barrier, making it unsuitable for treating meningitis. - Its spectrum of activity is more focused on anaerobic bacteria and some gram-negative organisms, not typically the main culprits in meningitis. *Gentamicin* - **Gentamicin** is an **aminoglycoside antibiotic** that has poor penetration into the CSF and is less effective as a monotherapy for meningitis. - It is often used in combination with other antibiotics, but not as an empirical monotherapy for suspected meningococcal meningitis.

Question 3: Which of the following drugs need not be stopped before surgery?

A. High Dose Aspirin
B. Metformin
C. Digitalis (Correct Answer)
D. Warfarin

Explanation: ***Digitalis*** - **Digitalis (digoxin)** is often continued through surgery, especially in patients with **heart failure** or **atrial fibrillation** to maintain cardiac function. - Its cessation could precipitate **cardiac decompensation** or arrhythmias, which are high-risk events during surgery. *High Dose Aspirin* - **High-dose aspirin** should generally be stopped before surgery due to its **antiplatelet effects**, increasing the risk of perioperative bleeding. - The duration of discontinuation depends on the type of surgery and individual patient risk. *Metformin* - **Metformin** should be stopped before surgery due to the risk of **lactic acidosis**, especially in situations involving **renal impairment** or hypoperfusion associated with surgery. - It's typically held on the day of surgery and for 24-48 hours post-operatively, depending on renal function. *Warfarin* - **Warfarin** is a strong oral anticoagulant that must be discontinued before most surgeries to prevent **excessive bleeding**. - It is typically stopped 5 days pre-op, and patients often receive **bridging therapy** with heparin, depending on their risk for thromboembolism.

Question 4: A patient presents to the emergency room with vomiting, diarrhea, high fever, and delirium. Upon physical examination, you notice large buboes, which are painful on palpation, and purpura and ecchymoses suggestive of disseminated intravascular coagulation. Gram stain on aspirate of a bubo reveals gram-negative rods with bipolar staining. Which of the following antibiotics is the drug of choice for empiric therapy?

A. Penicillin
B. Ceftazidime
C. Streptomycin (Correct Answer)
D. Chloramphenicol

Explanation: ***Streptomycin*** - The clinical presentation (high fever, delirium, **buboes**, purpura, ecchymoses, and **bipolar staining gram-negative rods**) is highly suggestive of **septicemic** or **bubonic plague** caused by *Yersinia pestis* [1]. - **Streptomycin** and **gentamicin** are the **drugs of choice** for treating plague, especially in severe forms [1]. *Penicillin* - **Penicillin** is effective against many gram-positive bacteria and some gram-negative cocci, but generally **not effective** against *Yersinia pestis*, a gram-negative rod. - Using penicillin would likely lead to treatment failure and worsening of the patient's condition given the severity of plague. *Ceftazidime* - **Ceftazidime** is a **third-generation cephalosporin** effective against a broad spectrum of gram-negative bacteria, including *Pseudomonas aeruginosa*. - While it has gram-negative coverage, it is **not considered the first-line empiric therapy** for suspected plague; aminoglycosides like streptomycin are preferred due to their established efficacy [1]. *Chloramphenicol* - **Chloramphenicol** is an effective antibiotic that can be used for plague, particularly in cases of **meningitis** due to its good central nervous system penetration. - However, for initial empiric therapy of **bubonic or septicemic plague**, **streptomycin** or **gentamicin** are generally preferred over chloramphenicol [1].

Question 5: Drugs of choice for MRSA in skin and soft tissue infections are:

A. Clindamycin, Vancomycin
B. Vancomycin, Linezolid (Correct Answer)
C. Vancomycin, Teicoplanin
D. Dicloxacillin, Vancomycin

Explanation: ***Vancomycin, Linezolid*** - **Vancomycin** is a cornerstone for treating **MRSA** infections, particularly severe ones, due to its efficacy against resistant staphylococci. - **Linezolid** is an alternative for **MRSA** infections, especially in cases of vancomycin resistance or intolerance, and offers good oral bioavailability. *Clindamycin, Vancomycin* - While **vancomycin** is correct, **clindamycin** has varying efficacy against **MRSA** and high rates of inducible resistance, making it less reliable as a primary drug of choice. - Clindamycin's use for MRSA often requires initial susceptibility testing, including a **D-test**, to rule out inducible clindamycin resistance. *Vancomycin, Teicoplanin* - **Vancomycin** is a primary **MRSA** drug, but **teicoplanin** is largely used in Europe and is structurally similar to vancomycin, often reserved for cases where vancomycin is not tolerated or preferred. - While effective, **teicoplanin** is not as universally recognized as a first-line option alongside vancomycin in all regions. *Dicloxacillin, Vancomycin* - **Vancomycin** is appropriate, but **dicloxacillin** is an **anti-staphylococcal penicillin** and is not effective against **MRSA** (Methicillin-Resistant Staphylococcus aureus) because MRSA, by definition, is resistant to all beta-lactam antibiotics. - Dicloxacillin is mainly used for **MSSA** (Methicillin-Sensitive Staphylococcus aureus) infections.

Question 6: Preferred time for prophylactic antibiotic administration for surgery?

A. 1 day before surgery
B. At the time of induction of anaesthesia (Correct Answer)
C. I.V. during surgery
D. I.M. 6 hrs before surgery

Explanation: ***At the time of induction of anaesthesia*** - This timing ensures that a **therapeutic concentration** of the antibiotic is present in the tissues at the time of the initial surgical incision, when the risk of bacterial contamination is highest. - Administering the antibiotic too early or too late can reduce its effectiveness in preventing **surgical site infections (SSIs)**. *1 day before surgery* - Administering antibiotics a day before surgery would lead to the drug being **metabolized and eliminated** from the body before the surgical incision is made, rendering it ineffective for prophylaxis. - This timing also increases the risk of **antibiotic resistance** development without providing adequate protection against SSIs. *I.V. during surgery* - Administering the antibiotic intravenously during surgery means that the drug will not have reached sufficient **tissue concentrations** at the crucial moment of the initial incision. - The protective effect is largely dependent on adequate tissue levels **prior to contamination**, which would not be achieved by administration only during the procedure. *I.M. 6 hrs before surgery* - While closer to the optimal timing than 1 day before, administering intramuscularly 6 hours prior may result in **suboptimal drug levels** at the time of incision, especially for drugs with shorter half-lives. - Intramuscular administration can also have variable absorption rates compared to intravenous, potentially delaying peak tissue concentration and reducing reliability for **prophylactic efficacy**.

Question 7: What is the most appropriate treatment for a patient with a suspected Brodie's abscess?

A. IV antibiotics only
B. Curettage and drainage (Correct Answer)
C. Amputation
D. Radiotherapy

Explanation: ***Correct: Curettage and drainage*** - **Brodie's abscess** is a subacute or chronic form of osteomyelitis involving a localized collection of pus in the bone - **Surgical intervention** with curettage and drainage is necessary to remove infected tissue and decompress the lesion - This approach directly addresses the localized bone infection, removes necrotic debris, and allows for local antibiotic delivery or culture-guided systemic therapy - Promotes healing and prevents recurrence by eliminating the sequestrum and poorly vascularized tissue *Incorrect: IV antibiotics only* - While antibiotics are crucial for treating osteomyelitis, **IV antibiotics alone** are insufficient for Brodie's abscess - The abscess creates an environment with **poor blood supply** to the central necrotic tissue, limiting antibiotic penetration and efficacy - Surgical debridement is essential to remove the avascular focus and allow antibiotics to work effectively *Incorrect: Amputation* - **Amputation** is an extreme measure reserved for severe, chronic, and uncontrollable osteomyelitis with extensive soft tissue damage or sepsis - Only considered when limb salvage procedures have failed or in cases of life-threatening infection - Not appropriate for a localized Brodie's abscess, which typically responds well to less invasive surgical methods *Incorrect: Radiotherapy* - **Radiotherapy** uses high-energy radiation to treat malignancies - Has **no role** in treating bacterial infections like Brodie's abscess - Would be inappropriate and potentially harmful in this clinical context

Question 8: A 60M diabetic presents with severe ear pain, otorrhea, and facial nerve palsy. CT reveals bony erosion of the temporal bone. His glucose level is 350 mg/dL. Most appropriate management?

A. Oral steroids
B. Intravenous antibiotics and surgical debridement (Correct Answer)
C. Antifungal therapy
D. Topical antibiotics

Explanation: ***Intravenous antibiotics and surgical debridement*** - This presentation suggests **malignant otitis externa**, a severe infection common in **diabetic** or immunocompromised patients, characterized by **severe ear pain**, **otorrhea**, **facial nerve palsy**, and **bony erosion** on CT. - The primary treatment involves high-dose, prolonged **intravenous antipseudomonal antibiotics** (e.g., piperacillin/tazobactam or ceftazidime with ciprofloxacin) and **surgical debridement** to remove necrotic bone and tissue. *Oral steroids* - **Oral steroids** are generally **contraindicated** in active bacterial infections, as they can suppress the immune system and worsen the infection, especially in a diabetic patient. - While steroids might be used later to manage inflammation *after* infection control, they are not the initial or primary treatment for **malignant otitis externa**. *Antifungal therapy* - **Malignant otitis externa** is primarily caused by **_Pseudomonas aeruginosa_**, a bacterium, not a fungus. - While fungal infections can occur in immunocompromised patients, the initial presentation and typical pathogens point to bacterial etiology, rendering antifungal therapy inappropriate as first-line treatment. *Topical antibiotics* - **Topical antibiotics** are insufficient for a severe, invasive infection like **malignant otitis externa** that has caused **bony erosion** and **cranial nerve involvement**. - Systemic, **intravenous antibiotics** are required to achieve adequate tissue penetration and eradicate the deep-seated infection.

Question 9: Which of the following is true about tenosynovitis of the finger?

A. Treatment is conservative.
B. Fingers held in mild extension / Extension deformity at the involved fingers.
C. With involvement of little finger the infection can spread to the ring finger.
D. Tenosynovitis of little finger will spread to thumb rather than ring finger. (Correct Answer)

Explanation: ***Tenosynovitis of little finger will spread to thumb rather than ring finger.*** - The **little finger's flexor tendon sheath** connects directly to the **ulnar bursa**, which communicates with the **radial bursa** (thumb's sheath) in approximately **80% of individuals** through the space of Parona. - This **bursal communication** creates a direct pathway for infection spread from the little finger to the thumb, making it the most common route of propagation in flexor tenosynovitis. *With involvement of little finger the infection can spread to the ring finger.* - While anatomically possible through **fascial plane connections**, direct spread to the ring finger is **less common** than spread to the thumb via established bursal pathways. - The **ulnar bursa-radial bursa connection** provides a more direct and frequently utilized route for infection propagation than lateral spread to adjacent digits. *Treatment is conservative.* - **Purulent flexor tenosynovitis** requires urgent **surgical incision and drainage** to prevent irreversible tendon damage and loss of function. - Conservative treatment with antibiotics alone is inadequate for established infections and may lead to **tendon necrosis** and permanent disability. *Fingers held in mild extension / Extension deformity at the involved fingers.* - Patients with tenosynovitis characteristically hold the affected finger in **mild flexion** as part of **Kanavel's four cardinal signs**. - **Extension** of the finger causes severe pain due to stretching of the inflamed tendon sheath, so patients avoid this position naturally.

Question 10: 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?

A. Mixed aerobic and anaerobic infection (Correct Answer)
B. Urinary diversion may be considered in severe cases
C. Bilateral orchidectomy is not routinely required
D. Anti-gas gangrene serum is indicated only in specific cases

Explanation: **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.

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