CIC CBIC Certified Infection Control Exam Free Practice Exam Questions (2026 Updated)

Group B Streptococcus (Streptococcus agalactiae) is the most common cause of neonatal bacterial meningitis beyond one week of age.

Step-by-Step Justification:

Group B Streptococcus (GBS) and Neonatal Infections:

GBS is a leading cause of late-onset neonatal meningitis (occurring after 7 days of age)​.

Infection typically occurs through vertical transmission from the mother or postnatal exposure.

Neonatal Risk Factors:

Premature birth, prolonged rupture of membranes, and maternal GBS colonization increase risk​.

Why Other Options Are Incorrect:

A. Group A: Rare in neonates and more commonly associated with pharyngitis and skin infections.

C. Group C: Typically associated with animal infections and rarely affects humans.

D. Group D: Includes Enterococcus, which can cause neonatal infections but is not the most common cause of meningitis.

CBIC Infection Control References:

APIC Text, "Group B Streptococcus and Neonatal Meningitis"​.

Even if the healthcare worker is negative for bloodborne pathogens, the patient has the right to be informed of a potential exposure. Transparency builds trust and aligns with ethical obligations in patient care.

The APIC Text states:

“Providers should inform patients when an HAI or other exposure event occurs, regardless of whether the exposure results in harm or is caused by negligence.” Courts and professional guidelines support disclosure.

CBIC and OSHA guidelines emphasize prompt and transparent reporting of exposures.

Options C and D are incorrect because the lack of infection does not negate the ethical duty to inform the patient.

Postoperative infections in clean surgical operations, defined by the Centers for Disease Control and Prevention (CDC) as uninfected operative wounds with no inflammation and no entry into sterile tracts (e.g., gastrointestinal or respiratory systems), are influenced by various perioperative factors. The Certification Board of Infection Control and Epidemiology (CBIC) emphasizes identifying and mitigating risk factors in the "Prevention and Control of Infectious Diseases" domain, aligning with CDC guidelines for surgical site infection (SSI) prevention. The question focuses on identifying a procedure not documented as a contributor to SSIs, requiring an evaluation of evidence-based risk factors.

Option C, "The use of iodophors for preoperative scrubs," has not been documented to contribute to the development of postoperative infections in clean surgical operations. Iodophors, such as povidone-iodine, are antiseptic agents used for preoperative skin preparation and surgical hand scrubs. The CDC’s "Guideline for Prevention of Surgical Site Infections" (1999) and its 2017 update endorse iodophors as an effective method for reducing microbial load on the skin, with no evidence suggesting they increase SSI risk when used appropriately. Studies, including those cited by the CDC, show that iodophors are comparable to chlorhexidine in efficacy for preoperative antisepsis, and their use is a standard, safe practice rather than a risk factor.

Option A, "Prolonged preoperative hospital stay," is a well-documented risk factor. Extended hospital stays prior to surgery increase exposure to healthcare-associated pathogens, raising the likelihood of colonization and subsequent SSI, as noted in CDC and surgical literature (e.g., Mangram et al., 1999). Option B, "Prolonged length of the operations," is also a recognized contributor. Longer surgical durations are associated with increased exposure time, potential breaches in sterile technique, and higher infection rates, supported by CDC data showing a correlation between operative time and SSI risk. Option D, "Shaving the site on the day prior to surgery," has been documented as a risk factor. Preoperative shaving, especially with razors, can cause microabrasions that serve as entry points for bacteria, increasing SSI rates. The CDC recommends avoiding shaving or using clippers immediately before surgery to minimize this risk, with evidence from studies like those in the 1999 guideline showing higher infection rates with preoperative shaving.

The CBIC Practice Analysis (2022) and CDC guidelines focus on evidence-based practices, and the lack of documentation linking iodophor use to increased SSIs—coupled with its role as a preventive measure—makes Option C the correct answer. The other options are supported by extensive research as contributors to SSI development in clean surgeries.

The most likely reason for the recall of a steam-sterilized load is the failure of the biological indicator (BI), specifically Geobacillus stearothermophilus, which is used to monitor high-temperature steam (moist heat) sterilization processes. This organism is the biological indicator of choice because it has high resistance to moist heat and thus serves as a reliable marker for sterilization efficacy.

The APIC Text and AAMI ST79 guidelines confirm that Geobacillus stearothermophilus is used for steam sterilization and that a failed BI indicates a failure in the sterilization process, which requires immediate action, including recalling all items sterilized since the last negative BI and reprocessing them. This is a crucial aspect of ensuring patient safety and preventing the use of potentially non-sterile surgical instruments.

According to the APIC Text:

"BIs are the only process indicators that directly monitor the lethality of a given sterilization process. [...] Geobacillus stearothermophilus spores are used to monitor steam sterilization..."

The CIC Study Guide (6th ed.) also specifies that:

"Evidence of sterilization failures (e.g., positive biological indicators) is the most common reason for a recall."

Additionally, it is noted:

“With steam sterilization, the instrument load does not need to be recalled for a single positive biological indicator test, with the exception of implantable objects.”

However, multiple positive BIs or BI failure confirmation does require a recall.

The incorrect options explained:

A. Bacillus subtilis – This is not used in steam sterilization but rather in dry heat or EO processes.

C. Placement of the biological indicator on the bottom shelf over the drain – While incorrect placement can lead to test failure, the recall is prompted by BI failure, not just placement.

D. Incorrect placement of instruments – This can cause sterilization failure but is not the direct trigger for a recall unless it leads to a failed BI.

The gold standard specimen for diagnosing pertussis (Bordetella pertussis infection) is a nasopharyngeal culture because:

B. pertussis colonizes the nasopharynx, making it the best site for detection.

A properly collected nasopharyngeal swab or aspirate increases diagnostic sensitivity.

This method is recommended for culture, PCR, or direct fluorescent antibody testing.

Why the Other Options Are Incorrect?

A. Cough plate – Not commonly used due to low sensitivity.

B. Nares culture – The nares are not a primary site for pertussis colonization.

C. Sputum culture – B. pertussis does not commonly infect the lower respiratory tract.

CBIC Infection Control Reference

APIC confirms that nasopharyngeal culture is the preferred method for diagnosing pertussis​.

A high-risk patient focus maximizes benefits while minimizing resource use in infection surveillance.

Step-by-Step Justification:

Efficiency of High-Risk Surveillance:

Targeting ICU, immunocompromised patients, or surgical units helps detect infections where the risk is highest, leading to earlier interventions​.

Resource Allocation:

Full hospital-wide surveillance is resource-intensive; focusing on high-risk groups is more efficient.

Why Other Options Are Incorrect:

B. Antibiotic monitoring:

Important for stewardship, but not the primary focus of infection surveillance.

C. Prevalence surveys:

Snapshot data only; does not provide ongoing monitoring.

D. Nursing care plan review:

Less direct in identifying infection trends.

CBIC Infection Control References:

APIC Text, "Surveillance Strategies for Infection Prevention"​.

The CBIC Certified Infection Control Exam Study Guide (6th edition) states that cytomegalovirus (CMV) is a common virus transmitted through direct contact with body fluids, including saliva, urine, blood, and respiratory secretions. In healthcare settings, Standard Precautions are sufficient to prevent CMV transmission, even for pregnant healthcare personnel.

Importantly, routine reassignment, work restriction, or removal from patient care is not recommended for pregnant HCP caring for patients with CMV, including those in the first trimester. The Study Guide emphasizes that the most effective preventive measure is strict adherence to Standard Precautions, particularly hand hygiene and appropriate use of personal protective equipment when contact with body fluids is anticipated. These measures have been shown to significantly reduce the risk of CMV acquisition.

Option A is incorrect because there is no indication for immediate post-exposure evaluation in the absence of a recognized exposure such as a needlestick or mucous membrane contact. Option B is not supported by evidence or guidelines and may contribute to unnecessary workforce restrictions. Option D is insufficient and misleading, as CMV is not transmitted via the airborne route and masking alone does not address the primary transmission risks.

For CIC® exam preparation, it is critical to recognize that education and reinforcement of Standard Precautions—not work exclusion—are the cornerstone of CMV prevention for pregnant healthcare workers.

The primary source of organisms causing surgical site infections (SSIs) is the patient’s own endogenous flora. Bacteria from the skin, mucous membranes, or gastrointestinal tract contaminate the surgical site, leading to infection. Common pathogens include Staphylococcus aureus, coagulase-negative staphylococci, and Enterobacteriaceae.

Why the Other Options Are Incorrect?

A. Operating room environment – While environmental contamination can contribute, it is not the primary source.

B. Operating room personnel – Infection control measures (hand hygiene, gloves, masks) reduce transmission from personnel.

D. Healthcare personnel’s hands – Although hand contamination is a risk, it is secondary to the patient’s endogenous flora.

CBIC Infection Control Reference

According to APIC guidelines, the patient’s own flora is the primary source of SSIs​.

The CBIC Certified Infection Control Exam Study Guide (6th edition) emphasizes that the primary purpose of construction barriers within an Infection Control Risk Assessment (ICRA) is to prevent the dissemination of dust and potentially infectious microorganisms generated during construction, renovation, or maintenance activities. Construction activities can aerosolize fungal spores (such as Aspergillus), bacteria, and other particulate matter that pose a significant risk to immunocompromised patients and other vulnerable populations.

Barriers must therefore be designed and maintained to effectively contain dust and microorganisms at the source, preventing their migration into occupied patient care areas. This containment function is the cornerstone of infection prevention during construction and directly aligns with ICRA goals of risk reduction and patient safety.

While the other options describe supportive or secondary considerations, they are not the most critical factor. Withstanding HVAC airflow (Option A) is important, but it serves the larger goal of containment. Sealing air intakes and exhausts (Option B) is a specific engineering control that may be used as part of containment strategies but does not define the primary purpose of barriers. Walk-off mats (Option D) are useful adjunctive controls but are insufficient alone to prevent airborne transmission of contaminants.

For CIC® exam preparation, it is essential to recognize that containment of dust and infectious agents is the defining function of construction barriers within an ICRA, and all other measures support this central objective.

==========

The CBIC Certified Infection Control Exam Study Guide (6th edition) follows the standardized surveillance methodology used for calculating central line days, which is essential for accurate reporting of central line–associated bloodstream infection (CLABSI) rates. A central line day is counted for each patient who has one or more central lines in place at the time of the daily count, regardless of the number of central lines present.

Therefore, if a patient has more than one central line, the patient is still counted as one central line day, making option C the correct statement. This approach ensures consistency and comparability of CLABSI rates across units and facilities.

Option A is incorrect because tunneled central venous catheters and implanted ports are included in central line counts if they meet the definition of a central line. Option B is incorrect because a central line is counted on any day it is present, even if it has been in place for less than 24 hours. Option D is incorrect because peripheral intravenous lines are not central lines and must never be included in central line day counts.

Accurate calculation of device days is a foundational surveillance competency for infection preventionists. Understanding these definitions is critical for valid CLABSI rate calculation, benchmarking, and performance improvement and is a frequently tested concept on the CIC® exam.

The correct answer is A, "Pregnant persons," as they should be excluded from receiving the live attenuated influenza virus (LAIV) vaccine. According to the Certification Board of Infection Control and Epidemiology (CBIC) guidelines, which align with recommendations from the Centers for Disease Control and Prevention (CDC) and the Advisory Committee on Immunization Practices (ACIP), the LAIV, commonly known as the nasal spray flu vaccine, contains a live attenuated form of the influenza virus. This vaccine is contraindicated in pregnant individuals due to the theoretical risk of the attenuated virus replicating and potentially harming the fetus, despite limited evidence of adverse outcomes (CBIC Practice Analysis, 2022, Domain III: Infection Prevention and Control, Competency 3.2 - Implement measures to prevent transmission of infectious agents). Pregnant persons are instead recommended to receive the inactivated influenza vaccine (IIV), which is considered safe during pregnancy.

Option B (healthy persons aged 2 to 49) is incorrect because this group is generally eligible to receive LAIV, provided they have no other contraindications, as the vaccine is approved for healthy, non-pregnant individuals in this age range (CDC Immunization Schedules, 2024). Option C (persons with allergies to chicken feathers) is not a contraindication for LAIV; the vaccine is produced in eggs, and while egg allergy was historically a concern, current guidelines indicate that LAIV can be administered to persons with egg allergies if they can tolerate egg in their diet, with precautions managed by healthcare providers. Option D (persons simultaneously receiving an inactivated vaccine) is also incorrect, as LAIV can be co-administered with inactivated vaccines without issue, according to ACIP recommendations, as there is no significant interference between the two vaccine types.

The exclusion of pregnant persons reflects CBIC’s emphasis on tailoring infection prevention strategies, including vaccination programs, to protect vulnerable populations while minimizing risks (CBIC Practice Analysis, 2022, Domain III: Infection Prevention and Control, Competency 3.1 - Collaborate with organizational leaders). This decision is based on precautionary principles outlined in CDC and ACIP guidelines to ensure maternal and fetal safety (CDC Prevention and Control of Seasonal Influenza with Vaccines, 2023).

The correct answer is D, "staff education related to loaner instrument reprocessing has occurred," as this is the infection prevention process that should be ensured when a surgeon is beginning a new procedure requiring loaner instruments within the next two weeks. According to the Certification Board of Infection Control and Epidemiology (CBIC) guidelines, loaner instruments—those borrowed from external sources for temporary use—pose unique infection prevention challenges due to potential variability in reprocessing standards and unfamiliarity among staff. Ensuring that staff are educated on proper reprocessing protocols (e.g., cleaning, sterilization, and handling per manufacturer instructions and AAMI ST79) is critical to prevent healthcare-associated infections (HAIs) (CBIC Practice Analysis, 2022, Domain III: Infection Prevention and Control, Competency 3.3 - Ensure safe reprocessing of medical equipment). This education should cover the specific requirements for loaner instruments, including documentation and verification of sterilization, and should occur proactively before the instruments are used to ensure competency and compliance.

Option A (items arrive in time for immediate use steam sterilization) is a logistical consideration, but it does not address the infection prevention process itself; timely arrival is necessary but insufficient without proper reprocessing validation. Option B (instruments are able to be used prior to the biological indicator results) is unsafe, as biological indicators are essential to confirm sterilization efficacy, and using instruments before results are available violates infection control standards. Option C (the planning process takes place after the instruments have arrived) is impractical, as planning (e.g., coordinating with vendors, assessing reprocessing needs) must occur in advance to ensure readiness and safety, not as a reactive step.

The focus on staff education aligns with CBIC’s emphasis on preparing healthcare personnel to handle loaner instruments safely, reducing the risk of contamination and ensuring patient safety (CBIC Practice Analysis, 2022, Domain IV: Education and Research, Competency 4.1 - Develop and implement educational programs). This proactive measure is supported by AAMI and CDC guidelines, which stress the importance of training for reprocessing complex or unfamiliar devices.

The Certification Study Guide (6th edition) stresses that valid comparison of infection rates requires consistent surveillance definitions and methodologies. When comparing a facility’s central line–associated bloodstream infection (CLABSI) rates to those reported in a national database, the single most important consideration is the use of the same case definition for central line infection. Without standardized definitions, rate comparisons are unreliable and may lead to incorrect conclusions about performance.

National databases rely on precise, standardized criteria for what constitutes a CLABSI, including timing, clinical signs, laboratory confirmation, and attribution to a central line. If a facility applies different criteria—such as alternative timing windows, inclusion/exclusion rules, or diagnostic thresholds—the resulting rates may be artificially higher or lower than benchmark data. The study guide emphasizes that comparability hinges on alignment of numerators (cases) and denominators (central line days) using identical definitions.

The other options, while relevant to prevention practices or contextual understanding, are not primary requirements for valid comparison. Skin preparation methods and types of lines influence risk but do not ensure comparability of reported rates. Facility size can affect risk profiles, but standardized definitions allow for risk adjustment within databases.

This question reflects a core CIC exam principle: benchmarking is meaningful only when surveillance definitions are consistent. Ensuring alignment with national definitions is foundational to accurate performance evaluation and quality improvement.

The CBIC Certified Infection Control Exam Study Guide (6th edition) emphasizes the importance of applying Spaulding’s classification to determine appropriate cleaning, disinfection, and sterilization levels for medical devices based on their intended use. According to this framework, rectal probes are classified as semi-critical devices because they come into contact with mucous membranes. Semi-critical devices require at least high-level disinfection after thorough cleaning.

An enzymatic solution, as listed in option C, is not a disinfectant. Enzymatic detergents are designed solely for cleaning, meaning they help remove organic material such as blood, mucus, and feces, but they do not kill microorganisms. Using an enzymatic solution alone for rectal probes is therefore inadequate and represents an improper disinfection practice, making this the scenario that clearly requires a protocol change.

Option A is acceptable because diaphragm fitting rings are noncritical devices that contact intact skin and may be safely processed using high-level disinfection. Option B is appropriate because blood pressure cuffs are noncritical items and can be disinfected using low- to intermediate-level disinfectants such as sodium hypochlorite. Option D is also appropriate, as cryosurgical probes are semi-critical devices and 2% glutaraldehyde is an accepted high-level disinfectant.

Recognizing the distinction between cleaning versus disinfection and applying the correct level of processing is a core competency for infection preventionists and a frequently tested concept on the CIC® exam.

==========

The correct answer is A, "Pertussis," as healthcare personnel should suspect this condition based on the presented symptoms and the patient’s incomplete vaccination history. According to the Certification Board of Infection Control and Epidemiology (CBIC) guidelines, pertussis, caused by the bacterium Bordetella pertussis, is characterized by an initial phase of mild respiratory symptoms (e.g., runny nose, low-grade fever) followed by a distinctive uncontrollable, rapid, and violent cough, often described as a "whooping" cough. This presentation is particularly concerning in adults with incomplete vaccination histories, as the pertussis vaccine’s immunity (e.g., DTaP or Tdap) wanes over time, increasing susceptibility (CBIC Practice Analysis, 2022, Domain I: Identification of Infectious Disease Processes, Competency 1.1 - Identify infectious disease processes). Pertussis is highly contagious and poses a significant risk in healthcare settings, necessitating prompt suspicion and isolation to prevent transmission.

Option B (rhinovirus) typically causes the common cold with symptoms like runny nose, sore throat, and mild cough, but it lacks the violent, paroxysmal cough characteristic of pertussis. Option C (bronchitis) may involve cough and fever, often due to viral or bacterial infection, but it is not typically associated with the rapid and violent cough pattern or linked to vaccination status in the same way as pertussis. Option D (adenovirus) can cause respiratory symptoms, including cough and fever, but it is more commonly associated with conjunctivitis or pharyngitis and does not feature the hallmark violent cough of pertussis.

The suspicion of pertussis aligns with CBIC’s emphasis on recognizing infectious disease patterns to initiate timely infection control measures, such as droplet precautions and prophylaxis for exposed individuals (CBIC Practice Analysis, 2022, Domain III: Infection Prevention and Control, Competency 3.2 - Implement measures to prevent transmission of infectious agents). Early identification is critical, especially in healthcare settings, to protect vulnerable patients and staff, and the incomplete vaccination history supports this differential diagnosis given pertussis’s vaccine-preventable nature (CDC Pink Book: Pertussis, 2021).

The preferred methodology for pre-work clearance in this scenario is the interferon-gamma release assay (IGRA), making option C the correct choice. This conclusion is supported by the guidelines from the Certification Board of Infection Control and Epidemiology (CBIC), which align with recommendations from the Centers for Disease Control and Prevention (CDC) for tuberculosis (TB) screening in healthcare workers. The employee’s history of receiving the Bacillus Calmette-Guérin (BCG) vaccination, a vaccine commonly used in some countries to prevent severe forms of TB, is significant because it can cause false-positive results in the traditional Tuberculin skin test (TST) due to cross-reactivity with BCG antigens (CBIC Practice Analysis, 2022, Domain I: Identification of Infectious Disease Processes, Competency 1.3 - Apply principles of epidemiology).

The IGRA, such as the QuantiFERON-TB Gold test, measures the release of interferon-gamma from T-cells in response to specific TB antigens (e.g., ESAT-6 and CFP-10) that are not present in BCG or most non-tuberculous mycobacteria. This makes it a more specific and reliable test for detecting latent TB infection (LTBI) in individuals with a history of BCG vaccination, avoiding the false positives associated with the TST. The CDC recommends IGRA over TST for BCG-vaccinated individuals when screening for TB prior to healthcare employment (CDC Guidelines for Preventing Transmission of Mycobacterium tuberculosis, 2005, updated 2019).

Option A (referral to tuberculosis clinic) is a general action but not a specific methodology for clearance; it may follow testing if results indicate further evaluation is needed. Option B (initial chest radiograph) is used to detect active TB disease rather than latent infection and is not a primary screening method for pre-work clearance, though it may be indicated if IGRA results are positive. Option D (two-step purified protein derivative-based Tuberculin skin test) is less preferred because the BCG vaccination can lead to persistent cross-reactivity, reducing its specificity and reliability in this context. The two-step TST is typically used to establish a baseline in unvaccinated individuals with potential prior exposure, but it is not ideal for BCG-vaccinated individuals.

The IP’s role includes ensuring accurate TB screening to protect both the employee and patients, aligning with CBIC’s focus on preventing transmission of infectious diseases in healthcare settings (CBIC Practice Analysis, 2022, Domain III: Infection Prevention and Control, Competency 3.2 - Implement measures to prevent transmission of infectious agents).

Perioperative normothermia maintenance reduces SSI rates by improving immune function and tissue perfusion​.

Routine wound irrigation (B) has no strong evidence supporting SSI prevention.

Prolonged antibiotic use (C) increases antibiotic resistance without added benefit.

Extended use of wound dressings (D) does not reduce SSI rates.

CBIC Infection Control References:

APIC Text, "SSI Prevention in Surgery," Chapter 12​.

Empiric antibiotic therapy is the immediate initiation of antibiotics based on clinical judgment before laboratory confirmation of an infection. In this case, the presence of fever, erythema, and tenderness at the central line site suggests a possible bloodstream infection, prompting empiric treatment with vancomycin.

Step-by-Step Justification:

Initiation Before Lab Confirmation:

Empiric therapy starts treatment based on symptoms while awaiting culture results​.

Prevents Complications:

Delayed treatment in central line-associated bloodstream infections (CLABSI) can lead to sepsis.

Common in High-Risk Situations:

Empiric treatment is used in cases where waiting for lab results could worsen the patient’s condition.

Why Other Options Are Incorrect:

B. Prophylactic:

Prophylactic antibiotics are given to prevent infection, not to treat an existing one.

C. Experimental:

Experimental treatment refers to clinical trials or unproven therapies, which does not apply here.

D. Broad spectrum:

Broad-spectrum antibiotics cover multiple bacteria, but empiric therapy may be narrow-spectrum based on suspected pathogens​.

CBIC Infection Control References:

APIC Text, Chapter on Antimicrobial Stewardship and Empiric Therapy​.

Chlorhexidine soap is a widely used antiseptic agent in healthcare settings for hand hygiene and skin preparation due to its effective antimicrobial properties. The Certification Board of Infection Control and Epidemiology (CBIC) underscores the importance of proper hand hygiene and antiseptic use in the "Prevention and Control of Infectious Diseases" domain, aligning with guidelines from the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO). Understanding the microbial activity of chlorhexidine is essential for infection preventionists to recommend its appropriate use.

Option D, "Persistent activity with a broad spectrum effect," is the true statement. Chlorhexidine exhibits a broad spectrum of activity, meaning it is effective against a wide range of microorganisms, including gram-positive and gram-negative bacteria, some fungi, and certain viruses. Its persistent activity is a key feature, as it binds to the skin and provides a residual antimicrobial effect that continues to inhibit microbial growth for several hours after application. This residual effect is due to chlorhexidine’s ability to adhere to the skin’s outer layers, releasing slowly over time, which enhances its efficacy in preventing healthcare-associated infections (HAIs). The CDC’s "Guideline for Hand Hygiene in Healthcare Settings" (2002) and WHO’s "Guidelines on Hand Hygiene in Health Care" (2009) highlight chlorhexidine’s prolonged action as a significant advantage over other agents like alcohol.

Option A, "As fast as alcohol," is incorrect. Alcohol (e.g., 60-70% isopropyl or ethyl alcohol) acts rapidly by denaturing proteins and disrupting microbial cell membranes, providing immediate kill rates within seconds. Chlorhexidine, while effective, has a slower onset of action, requiring contact times of 15-30 seconds or more to achieve optimal microbial reduction. Its strength lies in persistence rather than speed. Option B, "Can be used with any hand lotion," is false. Chlorhexidine’s activity can be diminished or inactivated by certain hand lotions or creams containing anionic compounds (e.g., soaps or moisturizers with high pH), which neutralize its cationic properties. The CDC advises against combining chlorhexidine with incompatible products to maintain its efficacy. Option C, "Poor against gram positive bacteria," is incorrect. Chlorhexidine is highly effective against gram-positive bacteria (e.g., Staphylococcus aureus) and is often more potent against them than against gram-negative bacteria due to differences in cell wall structure, though it still has broad-spectrum activity.

The CBIC Practice Analysis (2022) supports the use of evidence-based antiseptics like chlorhexidine, and its persistent, broad-spectrum activity is well-documented in clinical studies (e.g., Larson, 1988, Journal of Hospital Infection). This makes Option D the most accurate statement regarding chlorhexidine soap’s microbial activity.