Approximately 46.5 million surgical procedures and even more invasive medical procedures—including approximately 5 million gastrointestinal endoscopies—are performed each year. Each procedure involves contact by a medical device or surgical instrument with a patient’s sterile tissue or mucous membranes. A major risk of all such procedures is the introduction of pathogens that can lead to infection. Failure to properly disinfect or sterilize equipment carries not only risk associated with breach of host barriers but also risk for person-to-person transmission (e.g., hepatitis B virus) and transmission of environmental pathogens (e.g., Pseudomonas aeruginosa). 

Disinfection and sterilization are essential for ensuring that medical and surgical instruments do not transmit infectious pathogens to patients. Because sterilization of all patient-care items is not necessary, health-care policies must identify, based on the items’ intended use, whether cleaning, disinfection, or sterilization is indicated. 

Definition of Terms –

Sterilization describes a process that destroys or eliminates all forms of microbial life and is carried out in health-care facilities by physical or chemical methods. 

Disinfection describes a process that eliminates many or all pathogenic microorganisms, except bacterial spores, on inanimate objects 

Cleaning is the removal of visible soil (e.g., organic, and inorganic material) from objects and surfaces and normally is accomplished manually or mechanically using water with detergents or enzymatic products.   

Cleaning –

Thorough cleaning is essential before high-level disinfection and sterilization because inorganic and organic materials that remain on the surfaces of instruments interfere with the effectiveness of these processes. As the instruments are used, they are supposed to be immediately washed under running water to remove all dust contents. Post surgeries the blood spillage or adhered protein contents are difficult to remove with water. Enzymes can be used to remove such organic matter. 

• To remove protein content -protease enzyme 
• To remove carbohydrate/sugar – amylase enzyme 
• To remove lipid content- Lipase enzyme 

Disinfection –

Disinfection describes a process that eliminates many or all pathogenic microorganisms on inanimate objects, except bacterial spores. Disinfection is usually accomplished by the use of liquid chemicals or wet pasteurization in health care settings. The efficacy of disinfection is affected by several factors, each of which may nullify or limit the process’s efficacy.  

Some of the factors that affect both disinfection and sterilization efficacy are prior to the cleaning of the object; which includes 

• the organic and inorganic load present;  
• the type and level of microbial contamination;  
• the concentration of and exposure time to the germicide;  
• the nature of the object (e.g., crevices, hinges, and lumens);  
• the presence of biofilms;  
• the temperature and pH of the disinfection process; and,  
• in some cases, the relative humidity of the sterilization process (e.g., with ETO). 

 Sterilization –

Most medical and surgical devices used in healthcare facilities are made of materials that are heat stable and therefore undergo heat, primarily steam, sterilization. Sterilization destroys all microorganisms on the surface of an article or in a fluid to prevent disease transmission associated with the use of that item. Medical devices that have contact with sterile body tissues or fluids are considered critical items. These items should be sterile when used because any microbial contamination could result in disease transmission. Such items include surgical instruments, biopsy forceps, and implanted medical devices. 

Spaulding’s Classification 

Disinfection and sterilization are essential for ensuring that surgical instruments do not transmit infectious pathogens to patients. By definition, disinfection differs from sterilization by its lack of sporicidal property, but this is an oversimplification. A few disinfectants will kill spores with prolonged exposure times (e.g., 3 to 12 hours) and are called chemical sterilants. At similar concentrations but with shorter exposure periods (e.g., 12 minutes for 0.55% ortho-phthalaldehyde) these same disinfectants will kill all microorganisms except for large numbers of bacterial spores and are called high-level disinfectants. Low-level disinfectants may kill most vegetative bacteria, some fungi, and some viruses in a practical period of time (≤10 minutes), whereas intermediate-level disinfectants may be cidal for mycobacteria, vegetative bacteria, most viruses, and most fungi but do not necessarily kill bacterial spores. The germicides differ markedly among themselves primarily in their antimicrobial spectrum and rapidity of action. 

There are several kinds of instruments available in hospitals (medical devices, equipment & surgical materials). About 45 years ago, Earle H. Spaulding devised a rational approach to disinfection and sterilization of patient care items or equipment. 

The three categories Spaulding described for instruments used in hospitals are based on the contact or penetration levels of instruments on patient’s body and surroundings. The three categories are critical, semi critical, and noncritical. 

Critical Items 

These are so called because of the substantial risk for infection if such an item is contaminated with any microorganism, including bacterial spores. Thus, it is critical that objects that enter sterile tissue or the vascular system be sterile because any microbial contamination could result in disease transmission. E.g., surgical instruments, cardiac catheters, implants, pertinent components of the heart- lung oxygenator and the blood compartment of a hemodialyzer. Sterility at the time of use is required for these items. 

Semi-Critical Items 

These items come in contact with intact mucous membranes, but they do not ordinarily penetrate body surfaces. E.g., Noninvasive flexible and rigid fiberoptic endoscopes, endotracheal tubes, anesthesia breathing circuits, and cystoscopes  

Non-Critical Items  

These Items are those that either do not ordinarily touch the patient or touch only intact skin. Intact skin acts as an effective barrier to most microorganisms; therefore, the sterility of items that come in contact with intact skin is “not critical.” E.g., crutches, bed boards, blood pressure cuffs, stethoscope, bed-side cupboards, and other medical accessories. 

When properly used, disinfection and sterilization can ensure the safe use of invasive and non-invasive medical devices. However, disinfection and sterilization guidelines must be strictly followed. 

Reference: 

1. Mohapatra S. Sterilization and Disinfection. Essentials of Neuroanesthesia. 2017:929–44. doi: 10.1016/B978-0-12-805299-0.00059-2. Epub 2017 Mar 31. PMCID: PMC7158362. 

1. Centers for Disease Control & Prevention – Cleaning Disinfection & Sterilization Guidelines https://www.cdc.gov/infectioncontrol/guidelines/disinfection/cleaning.html#:~:text=Surgical%20instruments%20should%20be%20presoaked,difficult%2Dto%2Dclean%20instruments. 

1. Rutala WA, Weber DJ. Disinfection, Sterilization, and Control of Hospital Waste. Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases. 2015:3294–3309.e4. doi: 10.1016/B978-1-4557-4801-3.00301-5. Epub 2014 Oct 31. PMCID: PMC7099662. 

The word Nosocomial is derived from the Greek word Noso which refers to Disease and komeian refers to take care of. Studies shows that hospital acquired infections are a major cause of morbidity and mortality (sickness/ no. of death). 

What is Nosocomial infection? 

Infections that patients acquire while receiving healthcare treatment for other conditions are called Nosocomial Infections. As a result, Nosocomial Infections are also called Hospital Acquired Infections or Hospital Associated Infections. These infections or any other active or incubating infection are absent in the patient at the time of hospital admission. These infections occur: 

• up to 48 hours (about 2 days) after hospital admission 
• up to 3 days after discharge 
• up to 30 days (about 4 and a half weeks) after an operation 

Factors affecting HAI include- 

• Increased use of antibiotics 
• Transmission of pathogens from medical staff 
• In dwelling medical devices (Catheters, IV lines, Ventilators) 
• Surgical Instruments 
• Patient Surroundings 

Types of Healthcare-associated Infections 

Modern healthcare employs many types of invasive devices and procedures to treat patients and to help them recover. Infections can be associated with the devices used in medical procedures, such as catheters or ventilators. 

These healthcare-associated infections (HAIs) include central line-associated bloodstream infections, catheter-associated urinary tract infections, and ventilator-associated pneumonia. Infections may also occur at surgery sites, known as surgical site infections 

Central Line-associated Bloodstream Infection (CLABSI) 

A central line-associated bloodstream infection (CLABSI) is a serious infection that occurs when germs (usually bacteria or viruses) enter the bloodstream through the central line. Strict protocol when inserting the line helps to make sure the line remains sterile and a CLABSI does not occur. For more details click here  

Surgical Site Infection (SSI) 

A surgical site infection is an infection that occurs after surgery in the part of the body where the surgery took place. Surgical site infections can sometimes be superficial infections involving the skin only. Other surgical site infections are more serious and can involve tissues under the skin, organs, or implanted material. For more details click here  

Catheter-associated Urinary Tract Infections (CAUTI) 

A urinary tract infection (UTI) is an infection involving any part of the urinary system, including urethra, bladder, ureters, and kidney. UTIs are the most common type of healthcare-associated infection reported. Among UTIs acquired in the hospital, approximately 75% are associated with a urinary catheter, which is a tube inserted into the bladder through the urethra to drain urine. For more details click here 

Ventilator-associated Pneumonia (VAP) 

Ventilator-associated pneumonia is a lung infection that develops in a person who is on a ventilator. A ventilator is a machine used to help a patient breathe by giving oxygen through a tube placed in a patient’s mouth or nose, or through a hole in the front of the neck. An infection may occur if germs enter through the tube and get into the patient’s lungs. For more details click here 

Prevention of HAI 

HAI are preventable through strict adherence to guidelines by health care workers. Infection prevention and control programs are rooted in quality improvement activities that use protocols and interventions to decrease the risk of acquisition and transmission of infection within healthcare settings. 

Hand hygiene is the most important aspect of infection control and prevention of healthcare-associated infection (HAI). 

Personal protective equipment such as gloves, gowns, masks, and eye protection help protect from blood and body fluids. 

Monitoring and enforcing appropriate cleaning regimens are recommended to prevent bacterial transmission from the environment. 

Antimicrobial stewardship program – Overuse of antibiotics not only places patients at risk for developing medication side effects and CDI but also contributes to the heightening problem of antimicrobial resistance. 

Patient Education – Patients should be informed about the potential risk of developing HAI when receiving care. 

Conclusion 

Nosocomial infections form one of the most challenging tasks to deal with in a hospital setting. A significant percentage of HAI are preventable by simply following up various protocols which when supported by judicious antibiotic use can declutter the severity of the problem. Organized infection control measures, trained hospital staff, and continuous surveillance of HAI in healthcare settings will help deal with nosocomial infections. 

Reference: 

1. Thakkar J, Shanoo A, Gupta S, et al. (November 09, 2023) The Pattern and Impact of Hospital-Acquired Infections and Its Outlook in India. Cureus 15(11): e48583. doi:10.7759/cureus.48583 

1. Sikora A, Zahra F. Nosocomial Infections. [Updated 2023 Apr 27]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK559312/ 

1. Ken Inweregbu, Jayshree Dave, Alison Pittard, Nosocomial infections, Continuing Education in Anaesthesia Critical Care & Pain, Volume 5, Issue 1, 2005, Pages 14-17, ISSN 1743-1816, https://doi.org/10.1093/bjaceaccp/mki006 (https://www.sciencedirect.com/science/article/pii/S1743181617305759) 

1. Nair V, Sahni AK, Sharma D, Grover N, Shankar S, Chakravarty A, Patrikar S, Methe K, Jaiswal SS, Dalal SS, Kapur A, Verma R, Prakash J, Gupta A, Bhansali A, Batura D, Rao GG, Joshi DP, Chopra BK. Point prevalence & risk factor assessment for hospital-acquired infections in a tertiary care hospital in Pune, India. Indian J Med Res. 2017 Jun;145(6):824-832. doi: 10.4103/ijmr.IJMR_1167_15. PMID: 29067985; PMCID: PMC5674553. 

1. Healthcare-Associated Infections (HAI’s), Centers for Disease Control & Prevention https://www.cdc.gov/hai/index.html