Perioperative Antibiotic Prophylaxis — MCQs
In postoperative intensive care unit, five patients developed postoperative wound infection on the same day. The best method to prevent cross infection occurring in other patients in the same ward is to:
What is the optimal timing for administering antibiotic prophylaxis before surgery?
What is the treatment of choice for penicillin-resistant gonorrhea?
Which of the following is a first-generation cephalosporin used for surgical prophylaxis?
When do we have to start antibiotics to prevent post-operative infection?
Closure for clean wounds within 6 hours of injury is called.
A person is bitten by a dog. The dog and the person are fully immunized. There is a small abrasion mark on the site of bite. What would you advise to the person?
To prevent acute rheumatic fever, acute pharyngitis due to group A streptococci should be treated with antibiotics before:
Which of the following is the drug of choice for preoperative antibiotic prophylaxis in a patient undergoing cardiac surgery?
Post-exposure prophylaxis is indicated in?
Perioperative Antibiotic Prophylaxis Indian Medical PG Practice Questions and MCQs
Question 1: In postoperative intensive care unit, five patients developed postoperative wound infection on the same day. The best method to prevent cross infection occurring in other patients in the same ward is to:
- A. Practice proper hand washing (Correct Answer)
- B. Disinfect the ward with sodium hypochlorite
- C. Fumigate the ward
- D. Give antibiotics to all other patients in the ward
Explanation: ***Correct: Practice proper hand washing*** - **Proper hand hygiene** is the **single most effective method** for preventing the transmission of **healthcare-associated infections (HAIs)**, including surgical site infections - It physically removes or inactivates **transient microorganisms** from the hands of healthcare workers, thereby stopping their spread between patients - This is the **gold standard** recommended by **WHO, CDC**, and all major infection control guidelines for preventing **cross-infection** in healthcare settings *Incorrect: Disinfect the ward with sodium hypochlorite* - While disinfection with **sodium hypochlorite** is important for **environmental cleaning**, it is **less effective than hand hygiene** in preventing direct patient-to-patient transmission - Environmental disinfection alone **cannot interrupt the main routes of transmission**, which often involve **direct contact** or contaminated hands of healthcare personnel - This is a **secondary measure**, not the primary prevention strategy *Incorrect: Fumigate the ward* - **Fumigation** is typically used for **terminal disinfection** in specific situations, such as after highly contagious outbreaks, and is **not a routine** or primary method for preventing cross-infection in an active ward - Its effectiveness in preventing day-to-day cross-infection is **limited compared to immediate infection control practices** like hand hygiene - This practice is largely **outdated** in modern infection control protocols *Incorrect: Give antibiotics to all other patients in the ward* - **Prophylactic antibiotic use** in all other patients is **discouraged** due to the risk of **antimicrobial resistance (AMR)** and potential adverse effects - It does **not address the source of infection** or the transmission pathways, and can lead to wider public health issues - This is an **inappropriate primary prevention strategy** that violates antimicrobial stewardship principles
Question 2: What is the optimal timing for administering antibiotic prophylaxis before surgery?
- A. Immediately before induction of anesthesia
- B. 30-60 minutes before incision (Correct Answer)
- C. 2-3 hours before surgery
- D. Immediately after surgery
Explanation: ***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.
Question 3: What is the treatment of choice for penicillin-resistant gonorrhea?
- A. Erythromycin (a macrolide antibiotic)
- B. Ceftriaxone (a third-generation cephalosporin) (Correct Answer)
- C. Streptomycin (an aminoglycoside antibiotic)
- D. Ciprofloxacin (a fluoroquinolone antibiotic)
Explanation: ***Ceftriaxone (a third-generation cephalosporin)*** - **Ceftriaxone** is the recommended treatment for uncomplicated gonorrhea, including penicillin-resistant strains, given as a single intramuscular dose (500 mg IM). - It works by inhibiting bacterial cell wall synthesis and has excellent activity against *Neisseria gonorrhoeae*. - **Current guidelines recommend dual therapy:** Ceftriaxone plus azithromycin (or doxycycline) to prevent resistance development and cover potential co-infection with *Chlamydia trachomatis*. *Erythromycin (a macrolide antibiotic)* - While macrolides like azithromycin are used in combination with ceftriaxone, **erythromycin alone** is not effective first-line therapy for gonorrhea. - Its primary use in STIs is for chlamydia in specific situations, but not as monotherapy for gonorrhea. *Streptomycin (an aminoglycoside antibiotic)* - **Streptomycin** is an older antibiotic primarily used for tuberculosis and plague, but it is not effective against gonorrhea. - It works by inhibiting protein synthesis but lacks the necessary spectrum and tissue penetration for *Neisseria gonorrhoeae*. *Ciprofloxacin (a fluoroquinolone antibiotic)* - **Ciprofloxacin** was previously used for gonorrhea, but widespread resistance has developed globally, making it unreliable. - Due to high rates of fluoroquinolone resistance, it is **no longer recommended** for empiric treatment of gonorrhea by CDC/WHO guidelines.
Question 4: Which of the following is a first-generation cephalosporin used for surgical prophylaxis?
- A. Ceftriaxone
- B. Cefoxitin
- C. Cefazolin (Correct Answer)
- D. Cefepime
Explanation: ***Cefazolin*** - **Cefazolin** is a **first-generation cephalosporin** routinely used for **surgical prophylaxis** due to its effective coverage against common skin flora like *Staphylococcus aureus* and streptococci. - Its **longer half-life** allows for less frequent dosing pre-operatively, making it practical for preventing surgical site infections. *Ceftriaxone* - **Ceftriaxone** is a **third-generation cephalosporin** with a broader spectrum of activity, including good coverage against many gram-negative bacteria, but it is not typically the first choice for routine surgical prophylaxis. - It is more commonly reserved for treating serious infections such as **meningitis**, **gonorrhea**, and complicated intra-abdominal infections. *Cefoxitin* - **Cefoxitin** is a **second-generation cephalosporin** known for its excellent activity against **anaerobic bacteria**, in addition to gram-positive and some gram-negative organisms. - While it can be used for surgical prophylaxis in procedures with **high anaerobic risk** (e.g., colorectal surgery), it is not a first-generation cephalosporin. *Cefepime* - **Cefepime** is a **fourth-generation cephalosporin** with a very broad spectrum of activity, including excellent coverage against **Pseudomonas aeruginosa** and improved activity against gram-positive bacteria compared to third-generation cephalosporins. - It is reserved for severe infections, such as **febrile neutropenia** and hospital-acquired pneumonia, and is not generally used for routine surgical prophylaxis.
Question 5: When do we have to start antibiotics to prevent post-operative infection?
- A. 1 week before surgery
- B. 2 days before surgery
- C. After surgery
- D. 30-60 minutes before incision (up to 24 hours post-op) (Correct Answer)
Explanation: ***30-60 minutes before incision (up to 24 hours post-op)*** - Surgical antibiotic prophylaxis (SAP) should be administered **30-60 minutes before surgical incision** to ensure adequate tissue and serum concentrations at the time of incision. - This timing allows optimal drug distribution to surgical tissues, which is crucial for preventing surgical site infections (SSIs). - For most clean and clean-contaminated surgeries, prophylaxis should be limited to a **single dose** or continued for **maximum 24 hours post-operatively** as per WHO and CDC guidelines. - Prolonged post-operative antibiotics beyond 24 hours do **not** reduce infection rates and increase the risk of **antibiotic resistance** and **adverse effects**. *1 week before surgery* - Administering antibiotics this far in advance is **unnecessary** and **ineffective** for surgical prophylaxis. - It increases the risk of **antibiotic resistance** and does not guarantee adequate drug levels at the time of incision. - Pre-operative antibiotic use should be avoided unless treating an active infection. *2 days before surgery* - This timeframe is too early to achieve prophylactic benefit during the surgical procedure. - Prolonged pre-operative use promotes **bacterial resistance** without providing additional protection. - Drug levels will not be optimal at the time of incision due to metabolism and excretion. *After surgery* - Starting antibiotics **after surgical incision** is **too late** for prophylaxis as contamination has already occurred. - Post-operative initiation is considered **therapeutic treatment** for established infection, not prevention. - The critical window for prophylaxis is the period from skin incision to wound closure.
Question 6: Closure for clean wounds within 6 hours of injury is called.
- A. Primary closure (Correct Answer)
- B. Delayed primary closure
- C. Secondary closure
- D. Tertiary closure
Explanation: ***Primary closure*** - **Primary closure** is the immediate closure of a wound, typically within **6 hours** of injury, for **clean wounds** at low risk of infection. - This method promotes direct apposition of wound edges, leading to **faster healing** and **minimal scarring**. *Delayed primary closure* - This involves leaving a wound open for **4-6 days** to monitor for infection or edema, then closing it if conditions are favorable. - It is often used for **contaminated wounds** or those with a higher risk of infection, where immediate closure is not safe. - Also known as **tertiary closure**. *Secondary closure* - **Secondary closure**, or healing by secondary intention, occurs when a wound is left open and allowed to **heal naturally by granulation, contraction, and epithelialization**. - This method is used for **heavily contaminated** or **infected wounds** and results in a larger scar and a longer healing time. *Tertiary closure* - **Tertiary closure** is another term for **delayed primary closure**. - It involves leaving a wound open initially, then closing it after several days (typically 4-6 days) once the risk of infection has decreased. - This option is incorrect because the question asks about closure **within 6 hours**, not delayed closure.
Question 7: A person is bitten by a dog. The dog and the person are fully immunized. There is a small abrasion mark on the site of bite. What would you advise to the person?
- A. Amoxiclav
- B. Metronidazole
- C. Ciprofloxacin
- D. Observation (Correct Answer)
Explanation: ***Observation*** - This is a **Category II exposure** (minor abrasion/scratch) according to **WHO rabies classification**. With both the dog and person **fully immunized**, the recommended management is **immediate wound washing** with soap and water followed by **observation of the dog for 10 days**. - If the dog remains healthy during the 10-day observation period, no further rabies post-exposure prophylaxis is needed. The person's prior vaccination provides adequate protection. - **Prophylactic antibiotics are NOT routinely indicated** for minor abrasions in immunized individuals when the wound can be properly cleaned. The risk of significant bacterial infection in superficial wounds is low with proper wound care. - This approach follows **WHO and IAPSM guidelines** for rational dog bite management, avoiding unnecessary antibiotic use. *Amoxiclav* - Prophylactic antibiotics like **amoxicillin-clavulanate** are reserved for **high-risk wounds**: deep puncture wounds (Category III), wounds near bones/joints, hand/face wounds, delayed presentation (>8 hours), or immunocompromised patients. - A **small abrasion** in an immunized person does not meet criteria for routine antibiotic prophylaxis. Over-prescription contributes to **antimicrobial resistance**. - The primary concern in dog bite management is **rabies prevention**, not routine bacterial prophylaxis for minor wounds. *Metronidazole* - **Metronidazole** alone has limited coverage against common bite wound pathogens and would not be appropriate even if antibiotics were indicated. - It lacks activity against aerobic organisms like *Pasteurella* and *Staphylococcus* species commonly found in dog bites. *Ciprofloxacin* - **Ciprofloxacin** is not the first-line antibiotic for dog bites even when prophylaxis is indicated, due to limited anaerobic and Gram-positive coverage. - More importantly, antibiotics are **not routinely needed** for this Category II exposure with proper wound care and observation.
Question 8: To prevent acute rheumatic fever, acute pharyngitis due to group A streptococci should be treated with antibiotics before:
- A. 10 days of illness
- B. 7 days of illness
- C. 8 days of illness
- D. 9 days of illness (Correct Answer)
Explanation: ***9 days of illness*** - Treatment of **Group A Streptococcus (GAS)** pharyngitis with appropriate antibiotics within **9 days** of symptom onset effectively prevents subsequent acute rheumatic fever. - This timeframe is crucial because it allows for clearance of the bacteria before the immune response that triggers **rheumatic fever** becomes fully established. *10 days of illness* - This duration is **beyond** the optimal window for preventing acute rheumatic fever, as the immune response may already be sufficient to initiate the disease process. - While still beneficial for symptom resolution, antibiotic treatment initiated at this point is **less effective** in preventing the sequelae of rheumatic fever. *7 days of illness* - Administering antibiotics within **7 days** of illness is highly effective and falls within the appropriate treatment window for preventing acute rheumatic fever [2]. - However, **9 days provides a slightly longer, yet still effective, cutoff**, making prevention of rheumatic fever still possible within this slightly extended period. *8 days of illness* - Antibiotic treatment at **8 days of illness** is still considered within the therapeutic window for preventing acute rheumatic fever [2]. - The goal is to clear the infection and prevent the immune system from mounting the **autoimmune response** that leads to cardiac damage [1].
Question 9: Which of the following is the drug of choice for preoperative antibiotic prophylaxis in a patient undergoing cardiac surgery?
- A. Cefazolin (Correct Answer)
- B. Penicillin
- C. Clindamycin
- D. Vancomycin
Explanation: ***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**.
Question 10: Post-exposure prophylaxis is indicated in?
- A. Rabies
- B. Diphtheria
- C. HBV
- D. All of the options (Correct Answer)
Explanation: ***All of the options*** - Post-exposure prophylaxis (PEP) is a critical intervention for various infectious diseases, including **Rabies**, **Diphtheria**, and **HBV**, to prevent disease development after exposure. - The specific PEP regimen varies by disease but generally involves **vaccines**, **immunoglobulins**, or **antiviral medications**. **Rabies PEP:** - Rabies PEP is indicated after potential exposure to a rabid animal and involves a series of **rabies vaccine** doses and, for unvaccinated individuals, **rabies immune globulin (RIG)**. - Rabies is almost always fatal once symptoms appear, making timely PEP crucial. **Diphtheria PEP:** - Diphtheria PEP is recommended for close contacts of individuals with confirmed diphtheria and typically involves administering a **booster dose of diphtheria toxoid vaccine** and sometimes **antibiotics**. - This helps prevent the spread of *Corynebacterium diphtheriae* and disease development in exposed individuals. **HBV PEP:** - HBV PEP is critical after percutaneous or mucosal exposure to **HBV-infected blood** or body fluids. - It usually includes administering **hepatitis B vaccine** and, in some cases, **hepatitis B immune globulin (HBIG)**, depending on the exposed person's vaccination status and the source's HBV status.
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