2 курс / Микробиология 1 кафедра / Доп. материалы / Kartikeyan_HIV and AIDS-Basic Elements and Properties
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(Ananthnarayan & Paniker, 2000; Sathe & Sathe, 1991). In infants, hexachlorophane may get absorbed through the skin and cause neurotoxicity. Hence, a concentration of more than 3 per cent should not be used in neonatal units. Triclosan is used for controlling outbreaks of methicillin-resistant Staphylococcus aureus (MRSA) in nurseries (Simpson & Slack, 2006). It is poorly effective against Gram-negative organisms, mycobacteria, fungi, and viruses. Hexachlorophane is used in germicidal soaps and in deodorants to prevent bacterial decomposition of apocrine sweat. As a topical ointment, it is employed in the treatment of seborrhoeic dermatitis and impetigo (Ananthanarayan & Paniker, 2000; Chitnis, 1997).
Chloroxylenol: This is chlorinated derivative of phenol is available as concentrated solution, liquid soap, and soap cake under the brand name Dettol. Being relatively safe, it is used as a household skin antiseptic and for disinfecting plastic equipment. It requires a minimum contact period of 15 minutes for action on Gram-positive bacteria and more time is required in case of Gram-negative bacteria (Ananthanarayan & Paniker, 2000; Chitnis, 1997) Chloroxylenol is easily inactivated by organic matter and hard water and is not recommended for hospital use (Simpson & Slack, 2006).
Triclosan: It is chemically phenyl ether and is highly effective against Grampositive bacteria. It has moderate activity against Gram-negative bacteria, fungi, and viruses (Chitnis, 1997). Triclosan is used for controlling outbreaks of MRSA in nurseries (Simpson & Slack, 2006).
7.4.5 – Alcohols
Ethyl, isopropyl, and methyl alcohols have rapid and high levels of initial activity, but no residual activity. Optimal disinfecting activity is at 70–90 per cent concentration; antimicrobial activity decreases at both higher (more than 90 per cent), and lower (less than 70 per cent) concentrations (Chitnis, 1997; Simpson & Slack, 2006). Alcohols have good action on viruses, limited action on mycobacteria, and no action on spores, with reduced activity in presence of organic matter. Alcohol-based formulations of chlorhexidine, Savlon, and povidone iodine are used for hand-washing (Simpson & Slack, 2006).
Ethanol (synonym: ethyl alcohol): 100 per cent ethyl alcohol (called “absolute alcohol”) has poor antiseptic and disinfectant properties, while 60–70 per cent ethyl alcohol is a good general purpose skin antiseptic and can also be used to dilute other antiseptics, such as tincture iodine, chlorhexidine, and Savlon. It inactivates vegetative bacteria in a few seconds. Being a fat solvent, it can dissolve sebaceous secretions on the skin. However, its action on spores, viruses, and fungi is not reliable. It is volatile in warm climates. Methyl alcohol is added to ethyl alcohol to prepare methylated spirit to prevent consumption.
Isopropanol (synonym: isopropyl alcohol): It is more bactericidal, more of a fat solvent, and less volatile than ethanol. However, it is more toxic than ethanol,
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and its action on spores, viruses, and fungi is not reliable. Isopropanol is used at 70 per cent for skin antisepsis and for disinfecting clinical thermometers, incubators, and cabinets.
Methylated Spirit (synonyms: rectified spirit, denatured spirit): Methyl alcohol is added to ethyl alcohol to prepare methylated spirit to prevent consumption. A 70 per cent solution has bactericidal, fungicidal, and virucidal action. However, it is a volatile compound. It is used for decontaminating surfaces, such as metals and table tops, where use of household bleach and hypochlorites is contraindicated. A mixture of 70 per cent methyl alcohol and 1 per cent glycerine is used as a handwashing antiseptic (called “alcohol hand wash”), in all clinical settings. Glycerine is used in a concentration of 1 per cent as emollient to counter the drying effect of alcohol on the skin (Simpson & Slack, 2006).
7.4.6 – Aldehydes
Most aldehyde disinfectants are based on formulations of glutaraldehyde or formaldehyde, alone or in combination. Since they are an irritant to the eyes, skin, and respiratory mucosa, health and safety authorities in many countries control their use. Aldehydes are to be used only with adequate protection (protective clothing, safety hoods) of staff and ventilation of the working environment (air scavenging equipment). The treated equipment is to be thoroughly rinsed with sterile water to remove toxic residues. All chlorine-releasing agents should be removed from areas where formaldehyde fumigation is to be done, in order to prevent release of carcinogenic products (Simpson & Slack, 2006).
Glutaraldehyde: When buffered with sodium bicarbonate to pH 7.5–8.5, this has potent bactericidal, mycobactericidal, sporicidal, fungicidal, and virucidal action. The buffered solutions should be used within 2 weeks of preparation (Chitnis, 1997). Alkaline-buffered solution of glutaraldehyde is claimed to have a residual effect for several days but this will depend on the amount of contaminating organic material (Simpson & Slack, 2006). After disinfection with glutaraldehyde, the equipment should be thoroughly washed with sterile water. It is available under the brand name Cidex. A 2 per cent solution provides a high level of disinfection, which approximates sterilisation. It is the only disinfectant that can be reused. It is less toxic than formaldehyde and does not damage optical lenses and cementing material of endoscopes. However, glutaraldehyde has a strong odour and is expensive, as compared to formaldehyde. At alkaline pH (more than 8.5), glutaraldehyde gets polymerised, resulting in loss of antimicrobial activity. It is used for disinfecting sharp instruments, surfaces/instruments (which are destroyed by household bleach and sodium hypochlorite), face masks, catheters, endoscopes, endotracheal tubes, and respirators. An aqueous solution of 2 per cent is used topically for treatment of idiopathic hyperhidrosis of the palms and soles. Flexible endoscopes are to be disinfected by special closed washer–disinfector systems. These systems use oxidising agents, such as peracetic acid, chlorine dioxide, and super-oxidised water (Simpson & Slack, 2006).
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Formaldehyde: Commercially available formaldehyde (formalin) contains 35–40 per cent formaldehyde. The vapours are toxic and irritant. A solution used in 1:10 dilution (containing 3.5–4 per cent formaldehyde) inactivates vegetative forms of bacteria, viruses, and fungi in less than 30 minutes. Any equipment that is disinfected with formaldeyde should be thoroughly rinsed with sterile distilled water before reuse (Chitnis, 1997). It is a cheap disinfectant, which kills all vegetative bacteria, most viruses, and fungal spores, while mycobacteria and bacterial spores are killed slowly. It does not damage metals or fabric, but is an irritant to the eyes and respiratory tract. It can damage optical lenses and cementing material used in endoscopes. Formaldehyde tablets (used for disinfection of equipment and nursery incubators) are not reliable and need to be subjected to quality control after use (Chitnis, 1997). As aqueous solution (formalin), it is used for preserving biological specimens and cadavers, and for destroying anthrax spores in animal hair and woollen products. Woollen products are soaked in a 2 per cent solution of formalin at 40°C temperature for 2 minutes. Hair and bristles are soaked in a 2 per cent solution at 60°C temperature for 6 hours. This process is called “duckering”. A mixture containing one part formalin + one part glycerine + 20 parts water is used as a liquid spray for disinfecting walls and furniture in operation theatres, prior to fumigation. A 3 per cent solution may be used for removal of warts on palms and soles. Formalin in a concentration of 4 per cent is recommended for decontamination of spills of blood and body fluids. Formaldehyde vapour is used for fumigating operation theatres, wards, beds, books, and mattresses. Formaldehyde vapour is generated in special fumigators or by pouring 280 mL of 40 per cent formalin on 45 g of potassium permanganate (KMnO4) crystals per 1,000 cubic feet of space. The exposure period for fumigation is 36–48 hours (Chitnis, 1997). The excess gas is neutralised using ammonia vapour.
7.4.7 – Halogens
Halogens (compounds of chlorine and iodine) are relatively inexpensive and have a broad spectrum of action. Hence, they are commonly used for decontamination of surfaces (Chitnis, 1997). However, they are required in higher concentrations in the presence of organic substances such as blood, body fluids, excretions, or secretions.
Compounds of chlorine kill vegetative organisms and inactivate most viruses by strong oxidising effect of nascent chlorine. The disinfecting power of all chlorine compounds is expressed as “percentage of available chlorine” for solid compounds and as “percentage” or “parts per million” (PPM) for solutions. All chlorine-releasing agents should be removed from areas where formaldehyde fumigation is to be done, in order to prevent release of carcinogenic products (Simpson & Slack, 2006). Chlorine-releasing agents are corrosive and most compounds deteriorate rapidly (Ananthanarayan & Paniker, 2000; Chitnis, 1997).
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Sodium Hypochlorite: This compound is available as solution containing 5 per cent available chlorine, powder containing 60 per cent available chlorine, or tablets containing 1.5 g of available chlorine per tablet. The solution is available under various brand names such as Milton’s solution, Saaf, Chlorwat, Kloroklin. It is bactericidal, virucidal, cheap, and more effective than bleaching powder (CaOCl2) solution. However, it deteriorates rapidly, corrodes nickel and chromium plating of metallic instruments, and has an offensive odour. Sodium hypochlorite is most commonly used for bleaching and disinfecting linen and clothing: decontaminating spills of blood and body fluids; sterilising infant feeding bottles; and emergency disinfection of drinking water, fruits, and raw vegetables during epidemics.
Household Bleach: Also commercially available as fabric stain remover under various brand names, the solution contains 5 per cent available chlorine. It is bactericidal, virucidal, relatively cheap, and more effective than the solution of bleaching powder (calcium hypochlorite). For disinfecting materials and surfaces contaminated by blood or body fluids, household bleach should be made available in plastic recyclable bottles in hospitals and clinics. Household bleach deteriorates rapidly, corrodes galvanised buckets, nickel and chromium plating of metallic instruments, and has an offensive odour. The bleaching action may affect fabric and carpets while disinfecting spillage of blood or body fluids (Simpson & Slack, 2006).
Bleaching Powder: Chemically, this is calcium hypochlorite (CaOCl), also called “chlorinated lime”. Bleaching powder is an unstable compound and should contain 33 per cent of available chlorine. When stabilised by mixing with lime (calcium oxide) it is called “stabilised bleach” or “tropicalised chloride of lime” (TCL). Bleaching powder is used in powder form or as a freshly prepared solution. A 1 per cent solution of bleaching powder can be prepared by mixing one-fourth teaspoonful (1 g) of bleaching powder in 1 L of water. This gives a chlorine concentration of 1,000 PPM. The minimum contact period is half an hour. The OCl− ion is responsible for disinfection. Uses of bleaching powder: (a) decontaminating spills of blood and body fluids, (b) as a deodorant and disinfectant for toilets and bathrooms, (c) chlorination of water in wells (2.5 g of bleaching powder per 1,000 L of well water; contact period = 1 hour), (d) disinfection of faeces and urine (400 g of bleaching powder per litre; contact period = one hour), and (e) preparing Eusol, which was formerly used in dressing wounds.
Povidone Iodine: An “iodophor” is a loose complex of elemental iodine or triiodide with an anionic detergent, which increases solubility of iodine and functions as sustained-release iodine reservoir. “Povidone iodine” is a water-soluble complex of iodine and polyvinyl pyrrolidone (Simpson & Slack, 2006). Povidone iodine, which is available under various brand names, such as Betadine and Microshield, is an intermediate level disinfectant with bactericidal, fungicidal, and virucidal action. It does not stain or irritate the skin and is water miscible. However,
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it has poor residual effect. A freshly prepared dilution of povidone iodine is to be used everyday. It is relatively expensive and should not be used on copper and aluminium (Chitnis, 1997). It is used as a 0.75–1 per cent solution for hand wash; for disinfecting instrument trays, head-rests, and equipment; and for decontaminating spills of blood and body fluids. Aqueous or alcohol-based povidone iodine is used for skin antisepsis (preoperative preparation), peritoneal wash, and treating superficial mycoses, such as Tinea circinata (ringworm) and oral/vaginal moniliasis. One per cent solution used as gargles for pharyngitis. Due to its virucidal action, it is used for local treatment of wound in case of dog bite.
Sodium Dichloroisocyanurate (NaDCC): Also known as “Troclosene”, this compound is available as white powder, granules, and tablets. NaDCC powder containing 60 per cent available chlorine is recommended for decontamination of blood spills. The chemical is readily soluble in water. In solution, combined forms of chlorine (diand mono-chloroisocyanurate) exist in a 50:50 equilibrium with hypochlorous acid (HOCl) and nascent chlorine (Cl) – combined forms of chlorine. As the chlorine is used up, the free chlorine is released from combined forms so as to maintain the 50:50 equilibrium. The process continues till all the combined chlorine is depleted. NaDCC is used for disinfection of drinking water, decontamination of floors, blood spills, laboratory glassware, bedpans, and urine bottles. NaDCC kills bacteria, mycobacteria, fungi, viruses, and spores. Its disinfecting action is not generally affected by presence of organic matter such as faeces, algae, blood, pus, and serum. It has a long shelf life (up to 2 years) and is effective over a wide pH range of 4–9. It is relatively less corrosive to metals and relatively safe. The antidote for accidental ingestion is drinking plenty of milk.
7.4.8 – Surface-Active Agents
Anionic Detergents: Common soap is an anionic detergent. Hard soap contains saturated fatty acids and hydroxide of sodium, or potassium; while soft soap contains unsaturated fatty acids and hydroxide of sodium, or potassium. Anionic detergents reduce surface tension and wash away microorganisms, sebaceous secretions from the skin, and dirt. Soaps are moderately bacteriostatic against Gram-positive bacteria. They are used for washing hands and body parts, and for soap water enema (evacuation enema). However, soaps are incompatible with cationic detergents and are precipitated by hard water.
Cationic Detergents: These quaternary ammonium compounds are water-solu- ble and act mainly on Gram-positive vegetative bacteria. They reduce surface tension and wash away microorganisms, sebaceous secretions from the skin, and dirt. These compounds are heat-stable, even on autoclaving and are most active at neutral pH and slightly alkaline pH. However, they have no effect on most Gram-negative organisms and mycobacteria, and are inactivated by anionic detergents (common soap) and acidic pH. Cationic detergents combine with protein in organic matter such as pus, sputum, blood, and body fluids, and
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thus get inactivated. They are adsorbed by cotton, rubber, and porous material and potentially hazardous to neural tissue. Cationic detergents are used as gen- eral-purpose skin antiseptics in 1:1,000 dilution. For burns and wounds, 1:2,000 dilution is recommended. They are also used as disinfectants in 1:2,000 dilution for nylon (not rubber) tubings and catheters; and in 1:20,000 dilution for irrigation of bladder and urethra in catheterised patients. For preventing nappy rash, nappies may be washed in 1:8,000 dilution. A 5 per cent w/v (weight by volume) solution is recommended for topical use for treatment of dandruff (Pityriasis capitis). Benzalkonium chloride is a quaternary ammonium compound with strong action against Gram-positive bacteria. When EDTA is added as a chelating agent, it acts on Gram-negative organisms also (Chitnis, 1997).
Savlon: This is a combination of cetavlon (or Cetrimide, a cationic detergent) and chlorhexidine (Hibitane). Though it is inactivated by anionic detergents (common soap) and acidic pH, its advantages are its solubility in water and alcohol. When diluted with alcohol, it is a better disinfectant than when diluted with water. It reduces surface tension and washes away microorganisms and dirt. It is effective against Gram-positive, Gram-negative bacteria, and fungi. It is heat stable even on autoclaving and acts through a wide pH range of 5–8, but most effective at neutral and slightly alkaline pH. Savlon is effective even in the presence of organic matter. It is chiefly used as a skin antiseptic for general use. A 1 per cent solution of Savlon is used for disinfecting plastic appliances, clinical thermometers, and Cheatle’s forceps. The solution is to be changed daily.
7.4.9 – Miscellaneous Agents
7.4.9.1 – Hydrogen peroxide (H2O2)
Hydrogen peroxide (H2O2) is an unstable compound. A solution containing 6 per cent w/v (weight by volume) releases 20 times its volume of nascent oxygen
(O). Such a solution is called 20 volumes H2O2. It releases nascent oxygen (O), when applied to tissues. Nascent oxygen (O) prevents multiplication of anaerobic bacteria and inactivates HIV in 30 minutes. Effervescence mechanically removes tissue debris from inaccessible regions. It has good microbicidal and deodorant action (Simpson & Slack, 2006). However, presence of proteinaceous organic matter reduces its activity (Chitnis, 1997). Release of nascent oxygen
(O) and effervescence are of short duration. H2O2 should not be used in closed cavities, such as urinary bladder, due to its effervescence. It is to be stored in amber colour bottles and kept in a cold place. Being highly reactive and corrosive to skin and metals, it should not be used on copper, aluminium, brass, or zinc (Simpson & Slack, 2006). H2O2 is used for irrigating wounds, abscesses, and septic pockets to remove anaerobic conditions. In 1:8 dilution it is used as a deodorant gargle and mouthwash. It is also used for removing earwax and for disinfecting ventilators (Chitnis, 1997).
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7.4.9.2 – Other oxidising agents
Peracetic acid, chlorine dioxide, and superoxidised water are used as oxidising agents for disinfecting flexible endoscopes in special closed washer-disinfector systems (Simpson & Slack, 2006). Endoscopes are immersed in 0.35 per cent peracetic acid or 1100 PPM chlorine dioxide (ClO2) for 5 minutes. This alternative method is used since personnel handling glutaraldehyde may develop adverse reactions (Gangakhedkar, 1999).
7.4.9.3 – Ethylene oxide gas
Ethylene oxide is a highly penetrative, non-corrosive, and microbicidal gas. It is used in industry for sterilising heat-sensitive medical devices, such as prosthetic heart valves and plastic catheters. The devices to be sterilised are exposed to ethylene oxide gas at a concentration of 700–1,000 mg per litre for about 2 hours. When using ethylene oxide gas, the process of disinfection is complex, and requires appropriate temperature (45–60° Celsius) and high relative humidity (more than 70 per cent) for action, followed by post-treatment aeration (Simpson & Slack, 2006). Before sterilisation the devices to be sterilised should be cleaned thoroughly and wrapped in a material that allows the gas to permeate (Chitnis, 1997). Presence of salt reduces effectiveness of ethylene oxide (Simpson & Slack, 2006). During sterilisation adequate precautions should be taken because the gas is inflammable and is potentially explosive. It is also toxic to personnel. After sterilisation the product is aerated to remove residual gas (Simpson & Slack, 2006).
7.4.10 – Recommended Chemical Disinfection
For preventing transmission of blood-borne pathogens including HIV and HBV, the recommended concentrations of disinfectants are given below. “Clean” condition indicates that the item or surface has been already cleaned and is free from organic contamination. “Dirty” condition refers to contamination of item, article, or surface with organic substances such as blood, body fluids, and excretions.
Chlorine Releasing Compounds
1.Household bleach containing 5 per cent available chlorine: for “clean” condition – 1:50 dilution (20 mL/litre), and for “dirty” condition – 1:5 dilution (200 mL/litre)
2.Sodium hypochlorite solution containing 5 per cent available chlorine (0.1 per cent = 1,000 PPM = 1 g/L; 1.0 per cent = 10,000 PPM = 10 g/L): for “clean” condition – 0.1 per cent or 1:50 dilution (20 mL/litre), and for “dirty” condition 1.0 per cent or 1:5 dilution (200 mL/litre)
3.Calcium hypochlorite (bleaching powder) containing 70 per cent available chlorine: for “clean” condition – 1.4 g per litre, and for “dirty” condition -14 g per litre
4.Sodium dichloroisocyanurate (NaDCC) powder containing 60 per cent avail-
able chlorine: for “clean” condition – 1.7 g per litre, and for “dirty” condition −17 g per litre.
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5.Sodium hypochlorite-based tablets containing 1.5 g of available chlorine per tablet: for “clean condition – 1 tablet per litre, and for “dirty” condition – 4 tablets per litre.
6.Chloramine containing 25 per cent available chlorine: for “clean” condition – 20 g per litre, and for “dirty” condition – 20 or 40 g per litre. Chloramine releases chlorine slowly. The solution is freshly prepared every day, in non-metallic containers. Acids should not be used concomitantly since they displace chlorine gas.
Iodine Compounds
1.Tincture of Iodine (iodine 0.5 per cent + alcohol 70 per cent): for both “clean” and “dirty” conditions – 2.5 per cent.
2.Povidone iodine usually 10 per cent solution containing 1 per cent available iodine: for both “clean” and “dirty” conditions – 2.5 per cent. Freshly prepared dilution is to be used everyday. Povidone iodine should not be used on copper and aluminium.
Aldehydes
1.Glutaraldehyde (buffered): for both “clean”and “dirty”conditions – 2.0 per cent.
2.Formalin (40 per cent formaldehyde + 10 per cent methanol in water): for both “clean” and “dirty” conditions – 2.5 per cent.
Alcohols
1.Ethyl alcohol (ethanol): for both “clean” and “dirty” conditions – 70 per cent.
2.Isopropyl alcohol (isopropanol): for both “clean” and “dirty” conditions – 70 per cent.
3.Methylated spirit (also known as denatured or rectified spirit): for both “clean” and “dirty” conditions – 70 per cent.
Phenol Derivatives
1.Cresol: for “clean” conditions – 2.5 per cent, and for “dirty” conditions – 5.0 per cent.
2.Lysol (a saponified cresol): for both “clean” and “dirty” conditions – 2.5 per cent.
3.Chloroxylenols (4.8 per cent w/v is marketed as “Dettol”): for “clean” conditions – 4.0 per cent, and for “dirty” conditions – 10 per cent.
4.Chloroxylenols (4.8 per cent w/v) + EDTA: for “clean”conditions – 3.0 per cent, and for “dirty” conditions – 6.0 per cent.
Miscellaneous Disinfectants
1.Savlon (Cetrimide + Hibitane): for “clean” conditions – 5.0 per cent, and for “dirty” conditions – 10 per cent.
2.Ethylene oxide gas: 450–800 mg per litre is used for “clean” conditions. This compound is not recommended for use under “dirty” conditions.
3.Hydrogen peroxide (30 per cent stabilised solution): 6 per cent weight by volume (w/v) freshly prepared solution is used for “clean” conditions. This compound
is not recommended for use under “dirty” conditions. H2O2 is stored in amber colour bottles in a cold place. It should not be used on copper, aluminium, brass, or zinc.
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7.5 – BARRIER NURSING
Barrier nursing refers to use of physical or chemical barriers by all categories of hospital personnel and is not restricted to nursing staff. The objective of barrier nursing is to prevent the spread of pathogens through the intermediary of hospital staff. Health care providers with cuts, injuries, or infectious diseases should not be involved in patient care. While imparting mouth-to-mouth resuscitation, the risk of transmission of HIV is low. However, it is safer to use a barrier. Placing at least a gauze piece on the patient’s mouth is to be advocated (Gangakhedkar, 1999).
Pre-requisites for barrier nursing are:
1.Induction and periodic in-service training to all staff in asepsis
2.Disinfection and periodic health check-up of personnel to rule out carrier state
3.Fully functional and efficient Central Sterile Supplies Department (CSSD)
4.Availability of stand-by autoclave
5.Availability of separate isolation ward or special infectious disease hospital. During epidemics, makeshift arrangement may be made in school buildings and community centres, or home isolations can be organised
The procedures for effective barrier nursing include: (a) repeated hand washing after attending to each patient, (b) concurrent and terminal disinfection, (c) using PPE, (d) establishing multidisciplinary HICC, (e) periodic supervision of disinfection, and (f) microbiological surveillance.
Barrier nursing is indicated in high-risk areas such as infectious disease wards and hospitals, neonatal wards, premature baby units, intensive care units, postoperative wards, and burns wards.
There are three types of barrier nursing techniques. In cubicle nursing, patients suffering from the same type of disease are kept in a cubicle and a separate set of PPE is kept for each cubicle. Cohort nursing is practised in premature baby and neonatal units. A group of babies born on the same day are cared for by a nurse. In task nursing, each nurse performs a given task such as giving tablets or making beds, and washes her hands after attending to each patient.
7.6 – UNIVERSAL BIOSAFETY PRECAUTIONS
Synonym: Universal work precautions. The basic principle is that blood and body fluids from all patients ought to be considered potentially infected, irrespective of their serological status. In health care facilities, hepatitis B is much more transmissible than HIV, while hepatitis C is considered to be of intermediate risk. However, HIV/AIDS has caused fear in the minds of lay persons and also health care personnel due to its: (a) association with sexual minorities, socially marginalised groups, and heterosexual promiscuity, (b) lack of preventive vaccine or curative therapy, and (c) fear of impending death if infected with HIV (Gangakhedkar, 1999).
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The rapidly increasing prevalence rates of HIV infection in the general population increases the likelihood of occupational exposure to HIV. Transmission of HIV may be direct (contact with blood or body fluids) or through infected instruments. The major risk of transmission is through percutaneous exposure to infected blood or body fluids. Though infective doses of HIV are present in CSF, semen, blood, and cervico-vaginal secretions, HIV is present in different concentrations in almost all body fluids – amniotic, synovial, pleural, peritoneal, pericardial, sweat, faeces, nasal secretions, sputum, tears, urine, and breast milk of infected persons. Though CSF has the highest concentration of HIV, the likelihood of accidental occupational exposure to CSF is extremely low (CDC, 1988). The risk of transmission of HIV through exchange of fluids (other than sexual fluids and blood) tends to be extremely low or insignificant unless there is visible contamination with blood (Gandakhedkar, 1999). Lipophilic viruses such as HIV, HBV, and cytomegalovirus are highly sensitive to chemical disinfectants. In comparison, Mycobacteria, Pseudomonas, Staphy-lococci, spore-forming bacteria, fungi (Candida, Cryptococci), and hydrophilic viruses (polio virus, rhino virus) are not very susceptible to chemical disinfectants (Gangakhedkar, 1999).
7.6.1 – Controversies about Universal Precautions
It has been argued that universal precautions are too costly and time-consum- ing to be applied in case of every patient in every health care facility. The suggested alternative is to screen all patients for HIV antibodies before routine invasive procedures or surgery so that specific extra safety precautions can be taken. Extra safety precautions include selection of trained and experienced staff, restricting staff in the operating room to a bare minimum, and use of “surgical armour” for HIV-positive patients (2–3 pairs of gloves, impervious head gear, full-length waterproof apron, goggles, and rubber boots). Some surgeons are uncomfortable in such gear and feel their dexterity is compromised.
The pros and cons (Mitchell et al., 1997; Gangakhedkar, 1999) are given below.
Argument 1: Mandatory HIV screening will uncover previously undiagnosed HIV infection and special protective gear can be used for HIV-infected patients. From the community point of view, routine screening along with suitable counselling may limit HIV transmission by detecting more HIV-positive persons who would have otherwise remained undetected. Initiation of ARV therapy and follow up may prolong survival (Rhame & Mahi, 1988).
Counterpoint 1: Mandatory screening will not identify HIV-infected individuals during window period when there is high viraemia. A non-reactive HIV test during the window period may lead to complacency among staff and it is possible that procedures may be undertaken without adequate precautions. On the other hand, false positive results may lead to unnecessary panic among staff. It is possible that HIV-infected patients may be refused health care causing mental agony for the patient. Often, patients may require emergency surgery before