Every year, millions of surgical and even more invasive medical procedures are performed in healthcare and preventive institutions (HPI). A significant risk during these procedures is the transmission of infectious disease pathogens. The transmission of a pathogenic agent can occur both from person to person (for example, hepatitis B virus) and via objects in the hospital environment (for example, Pseudomonas aeruginosa).

Sterilization and disinfection are indispensable measures in the system of preventing the transmission and spread of nosocomial (hospital-acquired) infections (HAI).

The sterilization process is the destruction of all types and forms of microorganisms, including spores, on external objects by means of physical or chemical methods. Chemicals used to destroy all forms of microorganisms are called chemical sterilants. These germicides may also be used for high-level disinfection, which involves a shorter exposure time than sterilization.

Disinfection is the destruction of pathogenic microorganisms (except spore forms) on the surfaces of objects.

The scientist Spaulding developed a rational approach to the decontamination of medical devices, items, and equipment used for care. By dividing hospital equipment into critical, semi-critical, and non-critical items, he was able to definitively understand the system for conducting disinfection measures and which disinfectants should be used in specific situations.

Critical items are those that come into contact with sterile surfaces or body cavities or the bloodstream of a human and must be sterile. Even a minimal number of microbes on them poses a high risk of infection. Examples of critical items include surgical instruments, cardiac catheters, implants, and ultrasound probes used in sterile body cavities. Various sterilization methods are used for their decontamination, including chemical sterilization (in cases of thermolabile instruments where more reliable methods are impossible).

Semi-critical items contact mucous membranes. These include anesthesia and respiratory apparatus, some endoscopes, manometric esophageal probes, etc. Intact mucous membranes are usually resistant to bacterial spores but remain vulnerable to viruses, fungi, vegetative bacterial forms, including tuberculosis pathogens. Therefore, semi-critical items require high-level disinfection, which destroys all microorganisms (including tuberculosis mycobacteria) except some spores. Disinfectants with a short exposure time that ensure the destruction of tuberculosis mycobacteria are used.

Non-critical items contact intact skin and do not contact mucous membranes. Intact skin serves as an effective barrier against most microorganisms, and the sterility of items contacting it is considered non-critical. Examples include blood pressure cuffs, crutches, bedpans, floors, etc. A differentiated approach to disinfection procedures is needed depending on where non-critical items are used or located (whether used during procedures, surfaces in operating rooms, floors, or sanitary-technical equipment in restrooms). Accordingly, intermediate-level disinfectants (which destroy bacteria, viruses, fungi) or low-level disinfectants (which destroy vegetative bacteria, some viruses, and fungi) may be used.

Spaulding's classification is clear and logical and has been successfully applied in many developed countries for decades. However, it is time for changes. Over more than 30 years, new medical technologies have emerged, medicine has enriched with scientific discoveries—including in microbiology—successfully applied in practice. Equipment and apparatus have become more complex, multi-faceted, and made of various construction materials. Therefore, approaches to the decontamination of medical devices and hospital environment items require objective adjustments.

The volume and directions of disinfection measures in healthcare institutions depend on the profile of departments, the importance of compliance with anti-epidemic regimes, and the epidemiological process mechanism for different infectious diseases. Studies in healthcare facilities have shown a direct correlation between the amount of disinfectants used and the incidence of purulent-septic infections.

The issue of cleaning premises in healthcare institutions may seem premature and prosaic, but it has great importance for maintaining hospital environment safety and requires serious and competent attention.

Among sanitary-anti-epidemic measures that prevent HAIs, surface treatment in healthcare facilities occupies an important place. It should be a rule that risk zones (areas immediately adjacent to patients) are treated regularly and additionally if necessary (after contamination).

Surface treatment in healthcare premises consists of stages: cleaning dust, dirt, biological-origin substrates, and disinfection, i.e., destroying infectious disease pathogens. Ideally, a disinfectant that ensures broad-spectrum microorganism destruction and has cleaning properties for simultaneous surface washing is preferred. Hence, disinfectants with both disinfecting and good cleaning properties are favored.

Thus, disinfectants for surface treatment in healthcare facilities must meet these requirements: destroy pathogenic microorganisms at room temperature; have cleaning properties or be compatible with cleaning agents; have sufficiently low toxicity (safety class 4-3) to humans and not harm the environment; not damage surfaces of various materials; be stable, fire-safe, easy to use; and not fix organic contaminants.

To achieve a microbicidal effect, one must correctly select a disinfectant that suits the task. It is necessary to know the main properties, features, and characteristics of disinfectants.

Considering these criteria, it is advisable to primarily use disinfectants from the group of cationic surfactants (derivatives of guanidines, tertiary amines, quaternary ammonium compounds) for surface disinfection in healthcare facilities, as they have good cleaning properties. The recommended use is of composite preparations based on these chemical groups, providing a broad spectrum of antimicrobial action. Using disinfectants with prolonged antimicrobial action is advisable, especially for large surfaces during general cleaning.

Disinfectants based on polyguanidines (PAGIs), by creating a polymer film on treated surfaces, provide long-term protection against microorganism penetration and growth. Disinfectants combining polyguanidines with hydrogen peroxide as active substances are successfully used for surface decontamination. This ensures a high level of disinfection, prolonged action, and safety for personnel and the environment. Disinfectants based on glutaraldehyde can be used for decontamination but are unacceptable in the presence of patients due to toxicity. An exception is products combining glutaraldehyde with polyguanidine, where glutaraldehyde is in a bound state, preventing its evaporation into the air and inhalation by staff. Such products are essential for disinfection in rooms with especially high sanitary-epidemiological requirements (operating rooms, procedure rooms, etc.).

Use of chlorine-containing agents is acceptable if they have cleaning properties or if cleaning agents can be added before use. In healthcare practice, third-generation chlorine-containing disinfectants based on sodium dichloroisocyanurate have become widespread. This practice is well justified. Compared to other chlorine disinfectants, these are significantly more active against viruses and tuberculosis pathogens and less toxic.

Today, disinfectants from other chemical groups are not recommended for surface treatment in premises due to issues like fixing organic contaminants, toxicity, and others.

The strictest requirements apply to sanitary conditions and cleaning procedures in infectious, surgical, obstetric inpatient departments, procedure rooms, dressing and dental examination rooms, departments for immunocompromised patients, intensive care units, maternity hospitals, where the risk of HAIs is highest.

Currently, when choosing an appropriate disinfectant, the sensitivity of microorganisms to them is considered. To prevent resistant strain formation, it is justified to alternate disinfectants with different active substances. Healthcare institutions prepare a schedule for changing disinfectants, which is considered during procurement.

Before disinfection, medical staff must carefully study the methodical instructions for the disinfectant used, paying attention to the antimicrobial spectrum (whether the agent destroys microorganisms on surfaces), toxicity parameters (whether it can be used in the presence of people, safety measures), cleaning properties, preparation rules, and application methods.

Disinfectant solutions are prepared in a specially equipped room with supply and exhaust ventilation or in a fume hood. Staff preparing solutions must wear special clothing: gown, cap, mask, rubber gloves, and if required, respirators and protective goggles. Solutions are prepared by mixing disinfectant with tap water in special containers. Graduated containers facilitating precise dosing are preferable.

The amount of powdered disinfectant for solution preparation is weighed or measured using special measuring containers. Disinfectants in liquid or alcohol concentrates are measured with graduated glasses, pipettes, or syringes.

To achieve the required concentration, the recommended ratio of disinfectant to water must be followed (specified in methodical guidelines). Usually, water is poured first into the container, then the disinfectant is added, mixed, and covered until fully dissolved.

Depending on chemical nature, some solutions can be prepared in advance in closed containers and stored for some time; others must be used immediately. To avoid contamination by microorganisms, it is best to prepare solutions just before use or at the start of the work shift.

Disinfection using chemical agents can be performed by spraying surfaces with a disinfectant solution using hydrojets, automatic sprayers, or other equipment; aerosol application with fine droplet sprays; disinfecting sealed premises with aerosol disinfectants; wiping surfaces with cloths soaked in disinfectant; immersion of utensils, linens, toys, medical devices, and care items into disinfectant solutions; sprinkling secretions, food residues, carcasses, waste bins, soil, etc. with powdered disinfectants; treatment with paraformaldehyde mixtures in disinfection chambers for clothing, footwear, linens, and soft toys; filling technological containers, pipelines, and communications completely with disinfectant solution; circulating disinfectant through pipelines and sewage systems; diluting powdered or liquid disinfectants in water wells, pools, or artificial reservoirs.

The wiping method is considered most appropriate for surface disinfection in healthcare facilities, combining disinfection with cleaning.

For small, hard-to-reach surfaces or urgent disinfection of small areas, spraying with a hand sprayer or aerosol disinfectants is used.

During terminal disinfection, repurposing, or general cleaning, surfaces can be sprayed with hydrojets or devices allowing treatment of large volume rooms.

Sanitary-technical equipment is wiped with disinfectant-soaked wipes or cleaned with brushes soaked in disinfectant or cleaning-disinfecting powders, pastes, gels with cleaning, bleaching, deodorizing properties, often chlorine or oxygen-based.

Cleaning tools (cloths, wipes, sponges, scrubbers) are soaked after use in disinfectant, then washed or rinsed with tap water, dried, and stored separately. Used cloths and wipes can also be disinfected by boiling.

Containers used for disinfection are emptied, washed, and dried. Brushes are soaked for a specified time, rinsed with water afterward.

All cleaning materials must be kept in a separate room, each in its designated, labeled place according to the intended use.

When preparing disinfectant solutions, the following rules are important: measure or weigh the exact amount of disinfectant according to working concentration and volume; prepare solutions immediately before use to avoid activity loss; keep solutions in closed containers especially if volatile; store light-sensitive solutions in dark glassware or protected containers; do not add to partially used solutions; sterilize or disinfect containers before reuse.

The person preparing the solution must label containers with the product name, concentration, date, and sign.

For products that quickly lose active chlorine (e.g., sodium hypochlorite, bleaching powder), active chlorine content must be regularly measured before and during use by laboratory methods.

Optimal concentrations balancing cost and effectiveness should be sought.

The antimicrobial activity depends on solution concentration and exposure time. Common mistakes leading to ineffective disinfection include improper solution preparation (water mineralization or contamination, inappropriate temperature, absence of activators, incomplete dissolution); insufficient disinfectant concentration; inadequate exposure time; wrong choice of disinfectant for the task; heavy contamination with organic matter that interferes with cleaning; contamination by chemicals that inactivate disinfectants; unsuitable or contaminated containers; lack of lids; failure to alternate active substances.

When planning disinfectant procurement for a period, calculating purchase volumes can be challenging. To calculate the required quantity for an institution, the profile and capacity of the healthcare facility should be considered. Approximate formulas:

Consumption of antiseptics for surface disinfection during routine cleaning (X = annual need in kg or liters):

X = Q × (N × K / 100) × S(1)

Where:
Q = number of disinfections based on workdays and frequency per sanitary norms;
N = consumption rate of disinfectant solution per 1 sq.m (liters);
K = solution concentration;
S(1) = area of premises, furniture, medical equipment, sinks, etc., subject to disinfection.

Consumption for disinfection of medical equipment after patient use:

X = Q × (N × K / 100) × S(2) × r

Where:
S(2) = area of couch or dental chair or other equipment used;
Q = number of disinfections based on work shifts;
N, K as above;
r = average number of patients or visitors per shift.

Consumption for disinfection during general cleaning:

X = Q × (N × K / 100) × S(3)

Where:
Q = number of general cleanings per sanitary norms;
S(3) = total area including ceilings, floors, walls, equipment, furniture, window sills, sinks, faucets, door handles, etc.

Consumption for disinfection of sanitary-technical equipment (sinks, baths, showers):

X = Q × (N × K / 100) × S(4)

Where:
S(4) = surface area of sinks, baths, etc.

To objectively assess the cost of disinfection when choosing a disinfectant, compare the cost per 1 sq.m surface treated (Sp in UAH):

Sp = (Ci × D) / 1000

Where:
D = consumption of working solution for 1 sq.m (ml), per guidelines;
Ci = cost of 1 liter of working solution, calculated as:

Ci = A × B

Where:
A = cost of 1 liter (or kg) of disinfectant concentrate in UAH;
B = ml (or g) of concentrate needed to prepare 1 liter of working solution at specified concentration.

Taken and adapted from the journal "Chief Medical Nurse."