Infections represent a major risk to health care workers as well as patients (see also nosocomial infections), which is why preventing and controlling the spread of pathogens is a key aspect of clinical hygiene. A fundamental measure of infection prevention and control is proper hand hygiene, which involves regular hand washing and disinfection. Skin and mucous membrane disinfectants are typically alcohol-, phenol-, or iodine-based, whereas surface disinfectants rather employ aldehydes, halogens, oxidants, or ammonium compounds. Reusable medical equipment is sterilized by exposing it to heat over 120°C or, if the equipment is heat- or moisture-sensitive, to ethylene oxide gas or hydrogen peroxide gas plasma. In the surgical setting, the prevention of intraoperative surgical site infections involves the entire surgical team scrubbing in and donning sterile gowns and gloves before every procedure. Medical instruments that are exposed to blood pose an especially high risk for infection with bloodborne pathogens (e.g., HCV, HBV, HIV) and must be handled and disposed of with particular care. Accordingly, needlestick and sharps injuries require immediate management.
Needlestick infection prevention measures
Needlestick or sharps injuries 
- Definition: injuries caused by accidental penetration of the skin by any sharp object (e.g., scalpel, wires, pins, needles, glass shards), which pose a risk of infection with bloodborne diseases such as hepatitis B, hepatitis C, and/or HIV
- Epidemiology: ∼ 384,000 needlestick injuries (NSI) and other sharps-related injuries per year in the US
- Allow the wound to bleed for at least 1 minute by thoroughly rinsing the injury site with running water to minimize potential entry of pathogens into the bloodstream.
- Gently clean the wound with soap and water to reduce contamination with pathogens.
- Immediately see physician or nearest emergency department.
- Inform supervising physician and file accident report.
- History taking
- Blood testing
- Further measures and follow-up
Prevention of needlestick or sharps injuries
- Use of personal protective equipment (e.g., gloves, eye/face protection, gowns)
- Disposal of used needles in appropriate sharps disposal containers (no recapping)
- Use of medical devices with inbuilt safety features (e.g., blunt-tip suture needles, safety syringes)
- Hepatitis B vaccination for health care workers
The approximate risk of disease transmission from a needle stick injury if the source is known can be easily remembered using the rule of threes: up to 30% risk for hepatitis B, up to 3% risk for hepatitis C, and up to 0.3% risk for HIV.
In the United States, the Clinicians’ Post Exposure Prophylaxis (PEP) Line can be contacted at 1-888-448-4911 (http://www.nccc.ucsf.edu/) for information on the management of needlestick and sharps injuries
Pre-surgical infection prevention measures
- Aim: reduce the risk of an intraoperative surgical site infection through contamination with bacteria from the skin
- Who: all sterile staff members of a surgical team in the operating room (e.g., surgeons, scrub technicians, medical students assisting in a procedure)
Appropriate surgical attire 
- The fingernails should be short. No artificial nails and/or nail polish should be worn.
- All jewelry (e.g., bracelets, rings, watches) should be taken off.
- The surgical staff member should wear:
- Surgical scrubs
- Surgical footwear (e.g., closed rubber clogs, shoe covers)
- Surgical cap
- Surgical mask
- Protective eyewear
Material: Gowns and gloves have to be prepared before scrubbing.
- Gowns: Place the gown package on a clean surface. Pull on the outer edges of the wrapping to expose the gown without touching the sterile content that is inside.
- Gloves: Open the plastic packaging and let the inner sterile glove packet drop onto the gown.
- Indication: only required before the first case of the day or when the hands are visibly soiled
- Adjust the water temperature to a comfortable, lukewarm level.
- Open the scrub sponge package and set it on the side. The sponge is not used during the prescrub wash.
- Wet the hands and arms and apply antimicrobial soap.
- Start by washing the hands, followed by the arms, and lastly the elbows.
- Use the nail pick from the scrub sponge package to clean the subungual spaces under running water.
- Thoroughly rinse off the soap from the hands and arms.
Surgical hand disinfection
Scrubbing in (surgical scrub)
- Indication: before each operation, before gowning and gloving
- Methods: Every institution has its own protocol for scrubbing in. The two most common are the brush stroke method and the timed method.
- Always hold the hands at a higher level than the elbows.
- Start with the fingertips and work towards the elbows.
- Every area is only scrubbed once. Do not return to a previously scrubbed area.
- To ensure thorough cleaning, the fingers, hands, and arms should be seen as having four sides , each of which has to be brushed individually.
- Completely finish one side (left/right) before moving to the other hand and arm.
- The abrasive side of the scrub sponge (nail brush) is only used to clean the fingernails. 
- Neither the hands nor forearms should come in contact with any nonsterile object or surface (e.g., scrubs, tap). Otherwise, the entire scrubbing procedure needs to be repeated.
- After scrubbing, the hands should stay at a level between the waist and the neck at all times.
Instructions for the brush-stroke method 
- Remove the scrub sponge from the wrapper and moisten it under running water until you work up a sufficient lather.
- Put the fingertips of one hand together and brush the fingernails with the abrasive side of the scrub sponge for 30 strokes.
- Use the nonabrasive side of the scrub sponge to apply 10 strokes to all four sides of each finger, starting with the thumb. Do not forget the interdigital folds.
- Apply 30 strokes to the palm and 30 strokes to the back of the hand.
- Move on to the forearm. Mentally divide the arm into three equal increments, the most proximal of which ends two inches above the elbow. Scrub all four sides of each increment with 10 strokes, moving from distal to proximal.
- Switch sides and repeat steps 2–6.
- Discard the scrub sponge into the bin.
- Rinse off the foam.
- Start at the fingertips and move forward under the water in a single fluid motion.
- Do not move back and forth under the water.
- Completely rinse off one side before moving to the other.
- Wait and let the water drip from the elbows. Do not shake the arms.
- Dry off the hands with the sterile towel from the already opened gown package. (See “Preparation” above.)
- Take the towel without touching anything else.
- Dry off one side completely (hand before arm), then continue with the opposite side.
- Dab with the towel, rather than rub.
Alcohol-based disinfection (hand rub)
- Indication: This method is an alternative to scrubbing with a sponge.
- Substances: disinfectants containing alcohol and phenol mixtures
- Wash hands and forearms with nonantimicrobial soap. Thoroughly rinse off all foam.
- Completely dry off the hands and forearms with disposable paper towels.
- Use the elbow to dispense the disinfectant into the opposite hand.
- Set a timer and use the hands to thoroughly rub disinfectant on the hands and forearms for ≥ 3 minutes.
- During the set time, reapply disinfectant if necessary. All areas should have constant contact with the disinfectant.
Do not touch nonsterile objects and/or surfaces during the disinfection process. Otherwise, the entire routine needs to be repeated.
The hands should always be held at a higher level than the elbows.
- Indication: A sterile gown has to be donned for all surgical procedures. Often, surgeons are being gowned by an assistant that is already wearing sterile attire. However, every sterile member of the surgical team should be able to perform self-gowning.
Instructions: The gown needs to be prepared before scrubbing (see “Preparation” above).
- Pick up the folded gown, only touching the inner side.
- Identify the sleeve openings and slide the hands into it on both sides.
- Take a step back to ensure that the gown can not touch any nonsterile objects while unfolding.
- Let the gown unfold while simultaneously sliding the arms into the sleeves. At no point should the hands exit the sleeve cuffs. Keep the hands above waist level.
- An assistant will fasten the gown and secure it with a velcro tab at the neck and upper back.
- Proceed with gloving (see “ “ below).
- Pull only the left (shorter) tie out of the gown pass card.
- Pass the card to an assistant without letting the remaining tie slip from the card.
- Make a 360° turn so that the tie that is held by the assistant wraps around your waist.
- Pull the tie out of the card and secure both ties with a bow at your waist.
The gown is not considered sterile on the back, below the waist, or above the neck, because these areas are more likely to come in contact with unsterile objects.
Closed glove method
- Indication: preferred method when preparing for a surgical procedure
Instructions: Before starting closed gloving, a sterile gown must be donned.
- Open the sterile wrapper containing the gloves while the hands remain in the gown sleeves.
- Pick up the right glove by grabbing the folded cuff edge with the left sleeve-covered hand.
- Make sure the palm of the right hand faces the ceiling in the gown sleeve.
- Place the right glove on the right hand with the fingers of the glove pointing towards the shoulder. The palm of the glove should face the palm of the hand.
- Grab the palm-facing side of the folded cuff of the glove with the right sleeve-covered hand and hold onto it.
- Pull the ceiling-facing side of the folded cuff with the left sleeve-covered hand.
- Pull the glove up with the left hand and over the right hand.
- Pull the gown and glove up the arm to position your fingers inside the glove.
- Remove excessive gown sleeve from underneath the glove by pulling only on the gown. Make sure that the gown cuff stays fully covered by the glove cuff.
- Using the gloved hand, repeat the procedure for the other glove.
The gown cuff has to be fully covered by the glove cuff.
Open glove method
- Indication: predominantly used for smaller procedures that only require the hands to be sterile
- Ask an assistant to help you in retrieving the sterile wrapper containing the gloves from the plastic packaging.
- Place the sterile wrapper on a clean surface.
- Unfold the wrapper by grabbing the outer edges without touching the inner surface. The gloves should now be exposed.
- Take the folded edge of the right glove with the left hand and hold onto it. Insert the right hand into the glove and pull the cuff over the hand.
- Slide the fingers of the gloved hand underneath the rolled cuff of the left glove.
- Lift the glove so that the opening is facing upwards.
- Widen the opening with the fingers of the gloved hand that are underneath the cuff.
- Insert the fingers of the left hand and pull the cuff over the hand.
- Used for the care of all patients, whether or not an infection is probable
- Includes the following practices:
Hand disinfection 
Hand disinfection vs. hand washing
- Hand disinfection decreases transient skin flora more effectively and dehydrates the skin to a lesser extent compared to handwashing.
- Washing with soap should be kept to a minimum (e.g., before work, before surgical hand disinfection, in obvious soiling, after contact with a patient infected with spore-forming bacteria like Clostridium difficile).
- Use of skin care products is recommended to prevent skin irritation (e.g., during breaks, after work).
- Fingernails should be cut short. Artificial nails should not be worn.
- No jewelry on the hands and forearms
- Special rub-in technique for hygienic hand disinfection
- Wall-mounted dispensers are preferred to pocket-sized sanitizers.
- Avoid touching the face (eyes, nose, mouth)
Hygienic hand disinfection
- Aim: decrease the number of pathogens in transient skin flora
- Before and after contact with each patient
- Before work, before and after breaks, as well as before (self-protection) and after going to the bathroom.
- Before handling medication, syringes, and infusions
- After removing contaminated gloves
- Substances: alcohol and phenol mixtures
- Disinfection → minimum contact time: 30–60 seconds
- If desired, the hands may be subsequently washed.
- Used for the care of patients with drug-resistant pathogens (e.g., MRSA, VRE), enteric infections (e.g., Clostridioides difficile, Escherichia coli O157:H7), scabies, impetigo, and draining abscesses, all of which are capable of spreading through direct contact or .
- Includes performing hand hygiene and wearing gloves and gowns when getting into the patient's room (even when direct contact with the patient or infected material is not expected).
- Patients should be kept in isolation or in a cohort
- Medical equipment should be dedicated to a single patient. If not possible, disinfect before reuse.
- Used for the care of patients with suspected or confirmed infection with pathogens that can be transmitted via respiratory droplets (typically larger droplets > 5 μm in size) disseminated via coughing, sneezing, or talking; (e.g., Neisseria meningitidis, Bordetella pertussis, Influenza, Parainfluenza, Adenovirus, Haemophilus influenzae type B, Mycoplasma pneumoniae, and Rubella)
- Patients should be kept in isolation or in a cohort.
- Includes wearing masks within a distance of 3–6 feet from the patient and masking patients during transport
- Implement hand hygiene after contact with respiratory secretions.
- Used for the care of patients with suspected or confirmed infection capable of spreading via the dissemination of smaller droplets (i.e., particulates and aerosols < 5 μm in size), such as tuberculosis, measles, varicella, smallpox, and severe acute respiratory syndrome (SARS) infections
- Patients should be kept in airborne infection isolation rooms (AIIRs) with constant negative air pressure and frequent air changes (6–12 air cycles/hour) to prevent the contaminated air from escaping.
- Individuals must wear higher-level respirator), when entering the room., including an (or a
- Minimize transport of patients and mask them if it is mandatory.
- Implement hand hygiene after contact with respiratory secretions.
Prevention of catheter-associated urinary tract infections
- Avoiding unnecessary catheterization
- Using sterile technique during catheter placement
- Cleaning the catheter surrounding area with soap and water suffices for maintenance.
- Prompt removal when the catheter is no longer needed
- Using clean intermittent catheterization in patients with neurogenic bladder: In this technique, the catheter is immediately removed after bladder drainage and gets either discarded (single-use catheter) or cleaned (reusable catheter).
Prevention of intravascular catheter-related infections (e.g., infection)
- Implementing hand hygiene and strict aseptic technique during insertion
- Using a cap, mask, long-sleeved sterile gown, sterile gloves, and a sterile full-body drape
- Preparing skin with chlorhexidine and alcohol before inserting the catheter
- Systemic anticoagulation and antibiotics may be considered in oncology patients who require long-term central venous access.
- Changing dressings regularly
Prevention of ventilator-associated infections 
- Follow ventilator bundle protocol (a set of 4 standardized practices to prevent ventilator-associated infection)
- Use noninvasive ventilation where possible.
- Place tubes through the mouth rather than nose, if possible.
- Maintain proper patient oral hygiene (e.g., use of oral chlorhexidine).
- Consider antibiotic prophylaxis in patients that underwent emergency intubation.
Prevention of surgical site infections 
- Delay elective procedures until all infections, even those remote from the surgical site, are treated.
- In patients with planned surgery
- Ask the patient to cease smoking at least one month before surgery.
- Ask the patient to bathe or shower the night before the operation.
- Skin preparation routine in the operating room should include an alcohol-based agent.
- Parenteral periprocedural antimicrobial prophylaxis
- Should not be given routinely, except after cesarean deliveries
- If given, antimicrobial prophylaxis should to be timed to ensure appropriate concentrations at the time of incision.
- In clean and clean-contaminated procedures, no additional antimicrobial prophylaxis should be given after the incision has been closed.
- No topical antimicrobial agents should be applied to the incision.
- Blood glucose should be monitored; target levels during surgery are < 200 mg/dL.
- Ensure normothermia.
Periprocedural antimicrobial prophylaxis should not be given routinely, except after cesarean deliveries.
Prevention of community spread 
Social distancing means individuals should maintain a distance of ∼ 6 feet (2 meters) from others and avoid:
- Mass gatherings
- Congregate settings: crowded public places where close contact may occur (e.g., movie theaters, shopping centers)
- Quarantine: separation of a person or group of people who were exposed to the virus but are not yet symptomatic
- Isolation: separation of a person or group of people who are infected or reasonably believed to be infected with SARS-CoV-2
- Lockdown of communities or countries (e.g., only being allowed to leave home for medical care and groceries)
Sterilization and pasteurization
- Definition: the process of destroying all microbial life, including spores, on a surface or in a fluid.
- Medical equipment that has come into contact with sterile tissue or fluids must also be sterilized.
- Heat-stable equipment is sterilized mainly using steam (autoclave).
- Heat- and moisture-sensitive equipment (plastics, electrical devices, and corrosion-susceptible metal alloys) require low-temperature sterilization using, e.g., ethylene oxide, hydrogen peroxide gas plasma, peracetic acid.
Sterilization techniques for heat-stable equipment
Steam sterilization (autoclave)
- Exposing equipment to direct steam at a certain temperature and pressure for a specified period of time
- Mechanism of action: irreversible coagulation and denaturation of enzymes and structural proteins
- Active against bacteria, fungi, viruses, and spores
- Treated at > 121°C: typically uses 134°C for 3 minutes or 121°C for 15 min
- Prions are not destroyed by standard autoclaving. They must be sterilized at 121–132°C for 60 min (not a standardized method).
Dry air sterilization
- Exposing equipment to dry heat, which gets absorbed by the external layer and transferred inward to the interior layer by a process called conduction
- Denatures and oxidizes proteins and other cell components
- Commonly uses 170°C (340°F) for 60 min, 160°C (320°F) for 120 min, and 150°C (300°F) for 150 min
Sterilization techniques for heat- and moisture-sensitive equipment
Ethylene oxide gas sterilization
- Ethylene oxide: flammable and explosive gas
- The sterilization process includes preconditioning and humidification, gas introduction, exposure, evacuation, and air washes.
- Mechanism of action: alkylation of protein, DNA, and RNA
- Microbicidal against all microorganisms, with limited sporicidal effect due to spores resistance.
- Disadvantages: lengthy cycle time, costly, and hazardous
- Hydrogen peroxide gas plasma sterilization
- Aim: pathogen destruction through brief heating, especially of milk and other protein-containing products
- Procedure: treated with mild heat (< 100°C)
- Efficacy spectrum: destruction of a broad spectrum of bacteria but not heat-resistant spores
Common disinfectants and antiseptics 
Disinfectants and antiseptics equally destroy microorganisms or inhibit their growth and the terms are often used interchangeably. The difference is that disinfectants are used on nonliving surfaces, whereas antiseptics are used on living tissue.
|Most common disinfectants and antiseptics |
|Agent||Mechanism of action||Active against||Sporicidal|
|Alcohols (e.g., isopropyl alcohol and ethyl alcohol)|| || || |
|Bisbiguanides (e.g., chlorhexidine)|
|Phenol (e.g., orthophenylphenol and ortho-benzyl-para-chlorophenol)|
|Halogen-releasing agents||Iodine and iodophors (e.g., povidone-iodine and poloxamer-iodine)|| || |
|Chlorine-releasing agents (e.g., sodium hypochlorite and chlorine dioxide)|| |
|Hydrogen peroxide|| |
|Aldehydes (e.g., glutaraldehyde)|| |
|Quaternary ammonium compounds (e.g., benzalkonium chloride)|| |
Skin and/or mucous membrane disinfection 
- Commonly used agents: alcohols (e.g., ethanol) , biguanides, phenols
- Mechanism of action: protein denaturation
- Advantage: rapid onset of action and well tolerated
- Alternative: iodine preparations
Surface disinfection 
- Commonly used agents: aldehyde, halogens, ammonium compounds, oxidants (e.g., hydrogen peroxide)
- Mechanism of action: denaturation of various structures (proteins, nucleic acids, cell nuclei)
- Advantage: high efficacy also against spores and nonenveloped viruses, minimal decrease in antiseptic/disinfecting efficacy after contact with proteins (e.g., blood)
- Disadvantage: poorly tolerated
- The equipment worn for protection against and prevention of the further transmission of microbiological, chemical, and/or radiological hazards.
- Examples include gloves, gowns, masks, face shields, and respirators (e.g., N95 respirators and portable air-purifying respirators).
Putting on PPE 
- Long-sleeved isolation gown: Fully cover torso, extending from the neck to knees and end of wrists; then close the backside.
- N95 respirator or facemask: secure and fit
- Eye protection (e.g., goggles or disposable full-face shield): place and adjust
- Clean nonsterile gloves: cover wrist of isolation gown
Safely removing PPE 
- There are a variety of ways to remove PPE without contamination.
- Any part of the PPE directly exposed to the patient (especially the front and sleeves) is contaminated and should not be touched with ungloved hands during removal.
- All PPE (except for a respirator if worn) should be removed before leaving the contaminated space (e.g., patient room).
- Anytime hands are contaminated, immediately wash them, or use an alcohol-based hand sanitizer between steps.
Example 1 (in order)
- Using a gloved hand, grasp the palm area of the other gloved hand and peel it off.
- Hold removed glove in gloved hand.
- Slide fingers of ungloved hand under remaining glove at wrist (do not touch the gown!) and slide it inside out over the first glove.
- Discard gloves in a waste container.
- Goggles or face shield:
- Remove from the back by lifting the head band or ear pieces.
- If reusable: Place in designated receptacle; Otherwise, discard in a waste container.
- Unfasten ties without contacting body with sleeves.
- While only touching the inside, pull gown away from neck and shoulders.
- Turn it inside out over the arms.
- Roll into a bundle and discard in a waste container.
- Mask or respirator
- Grasp bottom ties or elastics, then together with the top ones, and remove upwards without touching the front.
- Discard in a waste container.
- Immediately wash hands or use an alcohol-based hand sanitizer.
Example 2 (in order):
- Gown and gloves together:
- Grasp the gown in front and pull away from the body until the ties break (only touch outside of gown with gloved hands).
- While removing the gown over the arms, roll the gown inside-out.
- Before the gown is removed from the wrists, using a gloved hand to grasp a portion of the glove of the other hand and sleeve of the gown together.
- With the glove and sleeve secured together, pull the arm of this side back, allowing the naked hand to exit the glove while only being exposed to the inside of the gown.
- Now using the ungloved hand, slide the remaining part of the gown and glove from the other side off, only touching the inside, in an inside-out manner and into the bundle.
- Place the gown and gloves into a waste container.
- Goggles or face shield:
- Remove from the back by lifting the headband or earpieces.
- If reusable: Place in the designated receptacle; otherwise, discard in a waste container.
- Mask or respirator
- Grasp bottom ties or elastics together with the top ones, and remove upwards without touching the front.
- Discard in a waste container.
- Immediately wash hands or use an alcohol-based hand sanitizer