Infection Control in Operating Room — MCQs

10 questions

Which of the following statements about iodophores is incorrect?

In a surgical post-op ward, a patient developed wound infection. Subsequently 3 other patients developed similar infections in the ward. What is the most effective way of preventing the spread of infection?

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?

What is the preferred method for sterilizing disposable syringes?

True about anesthesia machine – a) Cylinder is a part of high pressure system b) O2 flush delivers < 35 lit c) O2 flush delivers > 35 lit d) Pipeline is a part of low pressure system

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

The minimum time required for the sterilization of surgical instruments by moist heat at 134°C is:

Which of the following is true regarding prophylactic antibiotic use in surgical practice?

Which of the following is false about hydatid cyst:

Q10

Infection of all the following structures can be a cause of psoas abscess, except:

Infection Control in Operating Room Indian Medical PG Practice Questions and MCQs

Question 1: Which of the following statements about iodophores is incorrect?

A. Surfactants
B. Release iodine
C. Inorganic compounds (Correct Answer)
D. Disinfectant

Explanation: ***Inorganic compounds*** - Iodophores are **organic** complexes containing iodine, not inorganic compounds. - They are formed by combining iodine with a **solubilizing agent**, such as a surfactant or polymer. *Release iodine* - Iodophores are designed to **slowly release free iodine**, which is responsible for their bactericidal activity. - This gradual release mechanism provides a sustained antimicrobial effect. *Surfactants* - Many iodophores utilize **surfactants** (e.g., povidone-iodine) as the carrier molecule to improve solubility and penetration. - Surfactants help in the wetting and spreading of the iodine complex, enhancing its efficacy. *Disinfectant* - Iodophores are widely used as **antiseptics and disinfectants** due to their broad-spectrum microbicidal activity. - They are effective against **bacteria, viruses, fungi, and spores**.

Question 2: In a surgical post-op ward, a patient developed wound infection. Subsequently 3 other patients developed similar infections in the ward. What is the most effective way of preventing the spread of infection?

A. Fumigation of the ward
B. Wash OT instruments with 1% perchlorate
C. Proper hand washing of all ward personnel (Correct Answer)
D. Give IV antibiotics to all patients in the ward

Explanation: ***Proper hand washing of all ward personnel*** - **Hand hygiene** is the single most important and effective measure to prevent the spread of **healthcare-associated infections (HAIs)**, especially in a ward where multiple patients are affected. - It directly reduces the transmission of microorganisms from healthcare workers to patients and between patients. *Fumigation of the ward* - **Fumigation** is typically used for **terminal disinfection** or in situations involving highly resistant organisms or outbreaks, but it is not a routine or primary method for preventing day-to-day infection spread. - Its effectiveness is limited, and it can pose **health risks** to personnel and patients if not performed correctly, often requiring the ward to be vacated. *Wash OT instruments with 1% perchlorate* - This option focuses on the **sterilization of operating theater (OT) instruments**, which is crucial for surgical procedures but **irrelevant** to preventing the spread of wound infection within a general ward setting. - The problem describes a ward-based infection spread, not issues with surgical instrument sterility. *Give IV antibiotics to all patients in the ward* - **Prophylactic antibiotics** for all patients in a ward is generally **not recommended** as it can lead to **antibiotic resistance**, mask underlying infections, and cause adverse drug reactions. - Antibiotics should be prescribed judiciously based on specific indications and confirmed infections, not as a general preventive measure.

Question 3: 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 4: What is the preferred method for sterilizing disposable syringes?

A. Gas sterilization (Ethylene oxide) (Correct Answer)
B. Steam sterilization (Autoclave)
C. Chemical sterilization (Cidex)
D. Dry heat sterilization (Hot air oven)

Explanation: ***Steam sterilization (Autoclave)*** - While generally effective, **disposable syringes** are typically **pre-sterilized** by the manufacturer using methods like radiation or ethylene oxide and are not meant for resterilization. - Reusing and resterilizing disposable syringes, even with an autoclave, is **not recommended** due to potential material degradation and safety concerns. *Chemical sterilization (Cidex)* - **Cidex (glutaraldehyde)** is a high-level disinfectant primarily used for **heat-sensitive instruments** that cannot withstand high temperatures, such as endoscopes. - It involves **immersion** and is not suitable for the rapid, high-volume sterilization of plastic disposable syringes due to potential residue and material incompatibility. *Dry heat sterilization (Hot air oven)* - Requires **prolonged exposure** to high temperatures and is suitable for **glassware** and **oil-based substances**. - **Plastic disposable syringes** would melt or degrade at the required temperatures (160-170°C) for effective dry heat sterilization. *Gas sterilization (Ethylene oxide)* - **Ethylene oxide (EtO)** is the **preferred industrial method** for sterilizing heat-sensitive and moisture-sensitive medical devices, including **disposable plastic syringes**, by manufacturers. - It penetrates packaging effectively and sterilizes without damaging plastic, but requires specialized equipment and extensive aeration due to its **toxic and flammable nature**, making it impractical for point-of-use sterilization.

Question 5: True about anesthesia machine – a) Cylinder is a part of high pressure system b) O2 flush delivers < 35 lit c) O2 flush delivers > 35 lit d) Pipeline is a part of low pressure system

A. bc
B. a
C. ad
D. ac (Correct Answer)

Explanation: ***ac*** - **Cylinder** is indeed a component of the **high-pressure system** of an anesthesia machine, holding gases under high pressure before regulation. - The **O2 flush valve** bypasses the flowmeters and vaporizers, delivering a high flow of oxygen, typically **35-75 L/min**, to the common gas outlet. *bc* - This option is incorrect because while the O2 flush delivers a high flow, stating it delivers **< 35 L/min** is inaccurate; it typically delivers significantly more. - The implication that both b and c are correct cannot be true as they are contradictory (O2 flush cannot deliver both < 35 L/min and > 35 L/min simultaneously). *a* - This option is partially correct as the **cylinder** is part of the high-pressure system, but it omits the correct information about the O2 flush. - It does not account for the accurate statement regarding the flow rate of the O2 flush. *ad* - While the **cylinder** is correctly identified as part of the high-pressure system, the statement that the **pipeline** is part of the **low-pressure system** is incorrect; pipelines are part of the high-pressure system. - The low-pressure system begins after the flowmeters, encompassing components like the vaporizers and the common gas outlet.

Question 6: 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.

Question 7: The minimum time required for the sterilization of surgical instruments by moist heat at 134°C is:

A. 15 minutes
B. 30 minutes
C. 60 minutes
D. 3 minutes (Correct Answer)

Explanation: ***Correct: 3 minutes*** - At a temperature of **134°C**, the high pressure of **moist heat** (prevacuum sterilization) effectively denatures proteins and destroys all microorganisms, including spores, requiring only **3-4 minutes** of exposure time. - This short duration ensures rapid turnaround time for surgical instruments while achieving complete **sterilization**, making it ideal for urgent or flash sterilization cycles. - This is a standard protocol widely used in hospital autoclaves for wrapped instruments. *Incorrect: 15 minutes* - While 15 minutes is a common sterilization time, it is typically used at a lower temperature of **121°C** (gravity displacement sterilization) for moist heat sterilization. - At 134°C, a 15-minute exposure would be unnecessarily long, consuming more energy and time without additional sterilization benefit. *Incorrect: 30 minutes* - A 30-minute sterilization cycle is excessive for moist heat at **134°C**, indicating a misunderstanding of standard sterilization parameters. - This duration is more typical for sterilization at **121°C** with gravity displacement, or for large/dense loads requiring extended heat penetration time. *Incorrect: 60 minutes* - A 60-minute cycle is far too long for routine sterilization of surgical instruments at **134°C** with moist heat. - Such extended times are generally reserved for **dry heat sterilization** (160-180°C for 60-120 minutes) or very specific difficult-to-sterilize items with complex lumens.

Question 8: Which of the following is true regarding prophylactic antibiotic use in surgical practice?

A. is given orally
B. continued for a minimum of 7 days
C. first dose is given before induction of anesthesia (Correct Answer)
D. depends on individual preference

Explanation: ***First dose is given before induction of anesthesia*** - **Prophylactic antibiotics** are most effective when present in adequate concentrations in tissue **before the surgical incision** is made - Administering the first dose **within 60 minutes before incision** (typically before induction of anesthesia) ensures optimal tissue levels at the time of potential bacterial contamination - This timing is a **key principle** of effective surgical antibiotic prophylaxis *Is given orally* - Surgical prophylaxis requires **intravenous administration** for rapid and reliable tissue levels - IV route ensures predictable bioavailability and adequate drug concentration at the surgical site - Oral route may be used in specific outpatient scenarios but is **not standard** for surgical prophylaxis *Continued for a minimum of 7 days* - Prophylactic antibiotics are given for **short duration**: typically a **single dose** or continued for less than 24 hours post-operatively - Extended courses (≥7 days) are reserved for **treating established infections**, not prophylaxis - Prolonged use increases risk of **antibiotic resistance**, adverse effects, and *Clostridioides difficile* infection *Depends on individual preference* - Prophylactic antibiotic use follows **evidence-based guidelines** and institutional protocols, not individual preference - Guidelines consider surgery type, patient risk factors, local **antibiogram data**, and established efficacy - Standardized protocols improve outcomes and reduce surgical site infections

Question 9: Which of the following is false about hydatid cyst:

A. Most commonly involves lung (Correct Answer)
B. 20% saline is scolicidal
C. PAIR is employed for hepatic hydatid cysts
D. Ideally should be managed by pre-operative albendazole followed by surgery

Explanation: ***Most commonly involves lung*** - This statement is **false** because the **liver** is the most commonly involved organ in hydatid cyst disease (Echinococcosis), accounting for 60-70% of cases. - The lungs are the second most common site, seen in about 20-25% of cases. *20% saline is scolicidal* - This statement is **true** as hypertonic saline (typically 20-30%) is an effective **scolicidal agent** used during surgery or PAIR procedures. - It helps to kill the protoscolices within the cyst, reducing the risk of recurrence and anaphylaxis if spillage occurs. *PAIR is employed for hepatic hydatid cysts* - **PAIR (Puncture, Aspiration, Injection, Re-aspiration)** is a well-established and effective minimally invasive procedure for treating **hepatic hydatid cysts**. - It involves aspirating cyst fluid, injecting a scolicidal agent (like hypertonic saline or ethanol), and then re-aspirating the contents. *Ideally should be managed by pre-operative albendazole followed by surgery* - **Albendazole** is often given **pre-operatively** for several weeks (typically 4-6 weeks) to decrease cyst viability and reduce the risk of secondary hydatidosis if spillage occurs during surgery. - This combined approach of medical therapy followed by surgical excision is considered a standard for managing many hydatid cysts, particularly large or complicated ones.

Question 10: Infection of all the following structures can be a cause of psoas abscess, except:

A. Vertebrae
B. Hip joint
C. Appendix
D. Ribs (Correct Answer)

Explanation: ***Ribs*** - Infections of the ribs are typically confined to the **thoracic cage** and are less likely to directly spread to the **psoas muscle**, which lies deep within the abdomen and pelvis. - While severe rib infections might lead to systemic sepsis, direct extension to form a psoas abscess is anatomically improbable due to the **diaphragm** and intervening structures. *Vertebrae* - **Vertebral osteomyelitis** (especially of the lumbar spine) is a common cause of psoas abscess due to the close anatomical proximity of the psoas muscle to the vertebral bodies. - Infection can spread directly from the infected bone into the overlying psoas sheath. *Appendix* - **Retrocecal appendicitis**, particularly if perforated, can lead to direct extension of infection into the right iliac fossa and then into the right psoas sheath due to its anatomical location. - An inflamed or ruptured appendix can cause a **perforated appendicitis** and subsequent inflammatory response in adjacent structures. *Hip joint* - **Septic arthritis of the hip joint** can spread to the psoas muscle because the psoas tendon crosses anteriorly to the hip joint capsule, allowing for contiguous spread of infection. - Inflammatory fluid or pus from an infected hip can track along the fascial planes into the psoas sheath.

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