Which is the most likely means of transmitting infection between patients?
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Isolation of patients infected with transmissible pathogens decreases the risk of nosocomial transmission of organisms to staff and other patients. The specific type of isolation depends on the infecting agent and potential route of transmission.Transmission by contact is the most common mode of pathogen transmission and involves direct contact with the patient or contact with a contaminated intermediate object.Contact isolation requires the use of gown and gloves when in contact with the patient or immediate surroundings.Transmission by droplets involves the propulsion of infectious large particles over a short distance (<3 ft), with deposition on another's mucous membranes or skin.Droplet isolation requires the use of gloves and gowns, as well as masks and eye guards when closer than 3 ft to the patient.Airborne transmission occurs by dissemination of evaporated droplet nuclei (≤5 µm) or dust particles carrying an infectious agent.Airborne infection isolation (AII) requires the use of masks and negative pressure air-handling systems to prevent spread of the infectious agent. In the case of active pulmonary tuberculosis in older children and adults, severe acute respiratory syndrome (SARS), or avian influenza, the use of special high-density masks (N-95) or self-contained breathing systems such as powered air-purifying respirators (PAPRs) or controlled air-purifying respirators (CAPRs) are recommended. Positive pressure HEPA-filtered air-handling systems are used in some institutions for housing seriously immunocompromised patients and negative pressure systems for the care of patients with highly contagious respiratory infections such as Ebola virus. Show
Standard precautions are indicated for all patients and are appropriate for use in the clinic as well as the hospital. Additionally, for hospitalized patients, furthertransmission-based precautions are indicated for certain infections (Table 198.2). For contact and droplet isolation, single rooms are preferred but not required. Cohorting children infected with the same pathogen is acceptable, but the etiologic diagnosis should be confirmed by laboratory methods before exposing infected children to one another. Transmission-based isolation precautions should be continued for as long as a patient is considered contagious. The use of isolation techniques in outpatient settings has not been well studied. Professional offices should establish procedures to ensure that proper cleaning, disinfection, and sterilization methods are employed. Many practices and clinics provide separate waiting areas for sick and well children.Triage of patients is essential to ensure that contagious children or adults are not present in waiting areas. Outbreaks of measles and varicella in patients within the waiting area have been reported where the air exhaust from examination rooms enters the waiting area. Cleaning the clinic environment is important, especially in high-touch areas. Toys and items that are shared among patients should be cleaned between uses; if feasible, disposable toys should be used. Toys contaminated with blood or body fluids should be autoclaved or discarded. Sterilization and DisinfectionGeorge Freedman, ... Lakshman P. Samaranayake, in Contemporary Esthetic Dentistry, 2012 Transmission-Based PrecautionsTransmission-based precautions are required in patients known or suspected to be infected with highly transmissible or epidemiologically important pathogens, in which standard precautions may be insufficient to prevent transmission. The three types of transmission-based precautions are as follows: •Airborne transmission precautions—These apply to situations in which pathogens can be transmitted by the airborne route, that is, by small droplets of 5 µm or smaller (e.g., the organisms that cause tuberculosis, measles, and chickenpox and Aspergillus). •Droplet transmission precautions—These apply to situations in which pathogens can be transmitted by large particle droplets, greater than 5 µm (e.g., the organisms that cause mumps, rubella, and influenza). •Contact transmission precautions—These apply to situations in which pathogens can be transmitted by direct or indirect contact (e.g., methicillin-resistant Staphylococcus aureus [MRSA], herpes simplex virus, and hepatitis A virus). Using the concept of standard precautions, everyone who comes into the clinic should undergo the same protocols, unless more serious infectious such as tuberculosis are involved, in which case special protocols are employed. Standard precautions apply to contact with blood, body fluids, secretions, or excretions, except sweat. These precautions are used regardless of whether the fluids contain blood; they involve both nonintact skin and mucous membranes. No specific or special considerations are followed for patients with hepatitis. They should be treated in the same manner as other patients. There are other infectious diseases, such as airborne diseases, that are treated differently and with more precautions. In general practice it is important for each dental clinic to have infection-control protocols in place so that each staff member knows his or her role and performs infection control effectively. It is the duty of the dentist to determine protocols and ensure that the staff follows those protocols. Each clinic should have its own protocols, but some generalizations are possible. The dentist's role is to make sure that the staff members follow the instructions. The dental assistant's role is to properly perform cleansing and ensure that the instruments are adequately cleaned. The dental hygienist also makes sure that standard precautions are carried out in a proper way. The cleaning of the area is done mainly by dental assistants. View chapterPurchase book Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B9780323068956000323 Pediatric Healthcare EpidemiologyJane D. Siegel, Judith A. Guzman-Cottrill, in Principles and Practice of Pediatric Infectious Diseases (Fifth Edition), 2018 Transmission-Based PrecautionsTransmission-Based Precautions are designed for patients with documented or suspected infection with pathogens for which additional precautions beyond Standard Precautions are needed to prevent transmission. The 3 categories of Transmission-Based Precautions are Contact Precautions, Droplet Precautions, and Airborne Precautions, and they are based on the likely routes of transmission of specific infectious agents. Transmission-based precautions are combined for infectious agents that have more than 1 route of transmission. When used singly or in combination, such precautions always are used in addition to Standard Precautions. Transmission-based precautions applied at the time of initial contact, based on the clinical presentation and the most likely pathogens are referred to as Empiric Precautions or Syndromic Precautions. This approach is useful especially for emerging agents (e.g., SARS-CoV, avian influenza, pandemic influenza), for which information concerning routes of transmission is evolving. The categories of clinical presentation are as follows: diarrhea, central nervous system, generalized rash or exanthem, respiratory, skin or wound infection. Single-patient rooms always are preferred for children needing Transmission-Based Precautions. If single-patient rooms are unavailable, cohorting of patients, and preferably of staff, according to clinical diagnosis is recommended. The experience of treating EVD in the US in 2014 led to the development of special precautions after viral transmission to 2 nurses occurred as a result of patients' extraordinarily high viral loads and large volumes of emitted body fluids.6 PPE for all transmission-based precautions is donned upon entry into the room to protect against acquisition of pathogens from contaminated surfaces, even if direct contact with the patient is not intended. Although targeted Contact Precautions and universal gowning and gloving are effective for preventing transmission of infectious agents, potential adverse effects in patients placed on Contact Precautions have been described (e.g., depression, fewer visits from the healthcare team, increased rates of hypoglycemia or hyperglycemia, increased falls).80 Additionally, adherence to Contact Precautions decreases as the number of patients on Contact Precautions increases.81 Finally, a simulation study demonstrated contamination of HCP skin and clothing during doffing of gowns and gloves82; this study effectively demonstrated the PPE lessons learned during the SARS and EVD experiences. Evidence supports the importance of applying Contact Precautions only when indicated, obtaining training on the use of PPE, having effective PPE readily available, and practicing consistent and precise use of PPE.83 Table 2.2 lists the 3 categories of isolation based on routes of transmission and their necessary components. Table 2.3 lists precautions by syndromes, to be used when a patient has an infectious disease and the agent is not yet identified. For infectious agents that are more likely to be transmitted by the droplet route (e.g., pandemic influenza), droplet precautions (with use of surgical mask) are appropriate; however, during an aerosol-generating procedure, N95 or higher respirators are indicated.84 Read full chapterView PDFDownload book Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B9780323401814000025 Viral Infections, an Overview with a Focus on Prevention of TransmissionVincent Chi-Chung Cheng, ... Kwok-Yung Yuen, in International Encyclopedia of Public Health (Second Edition), 2017 Viral Transmission and Infection Control Prevention for Viral Agents Spread by ContactStandard and transmission-based precautions are important to prevent the spread of respiratory and gastrointestinal viral infection (Table 3). Some of the respiratory viruses such as respiratory syncytial virus (RSV), parainfluenza virus, and the gastrointestinal viruses, norovirus, and rotavirus are predominantly spread by direct contact. As an illustrative example, RSV is the most frequent cause of nosocomial infection in pediatric wards and causes lower respiratory tract disease in 40% of young children. Prolonged shedding of RSV for 3–11 days has been observed in immunocompetent children (Hall, 2000), and the virus can survive on inanimate surfaces for 6 h (Kramer et al., 2006). All these factors contribute to fomite-mediated transmission of RSV in the hospital. The risk of nosocomial RSV transmission was not related to age or underlying disease, but to length of hospitalization (Hall et al., 1975). Contact precautions with cohort nursing and wearing gloves and gowns during patient care resulted in a significant reduction in nosocomial transmission of RSV in three consecutive winters (Madge et al., 1992). In another study, the incidence of nosocomial acquisition of RSV was significantly decreased after implementation of wearing gloves and gowns and isolation of cases even though the duration of RSV shedding remained unchanged before and after the intervention (Leclair et al., 1987). Table 3. Infection control measures for transmission-based precautions in resource-poor areas Transmission-based precautions (example)Infection control measures in developed areasInfection control measures modified in resource-poor areasContact precautions (norovirus)Patient placement: single room isolation or cohort nursing For the gastrointestinal viruses, norovirus is the most famous agent to cause outbreaks in the community and hospital. Transmission is predominantly by the fecal–oral route. Numerous community outbreaks of norovirus have been reported in restaurants, resorts, cruise ships, schools, and nursing homes (Arvelo et al., 2012; Britton et al., 2014; Kuo et al., 2009; Lai et al., 2013; Wikswo et al., 2011). The emergence of a new variant of norovirus, genogroup II, type 4 (GII.4), in Australia, Europe, and North America associated with increased acute gastroenteritis activity has been reported since 2006 (Bruggink and Marshall, 2010; Hasing et al., 2013; Kanerva et al., 2009; Yen et al., 2011). Norovirus is a nonenveloped RNA virus which is relevantly resistant to common disinfectants. As norovirus is unculturable, feline calicivirus has been used as a surrogate for in vitro and in vivo testing for different preparations of disinfectants (Gehrke et al., 2004; Lages et al., 2008). In the WHO formulation AHR, formula I preparation contains ethanol (80% v/v) which, based on the above studies, may possess reasonable virucidal activity for norovirus when the contact time is prolonged for up to 30 s. Successful control of nosocomial outbreaks of norovirus by directly observed hand hygiene has been reported, especially during high-risk nursing care practices such as changing napkins and feeding (Cheng et al., 2009). A proactive infection control approach with the provision of ‘added test’ was implemented to prevent the occurrence of nosocomial outbreak when the new variant of norovirus, genogroup II, type 4 (GII.4) was circulating in Hong Kong (Cheng et al., 2011). RT-PCR for norovirus was performed as an ‘added test’ by the microbiology laboratory for all fecal specimens that were requested for bacterial culture, Clostridium difficile culture or cytotoxin, and rotavirus antigen detection without a request for norovirus detection. During the study period, almost 50% of newly diagnosed norovirus infections were detected by the added test. Timely implementation of infection control measures by single room isolation of index case with strict contact precautions significantly reduced the incidence of hospital-acquired norovirus infection from 131 (baseline) to 16 cases per 1000 potentially infectious patient-days (P < 0.001) (Cheng et al., 2011). Read full chapterView PDF Read full chapter URL: https://www.sciencedirect.com/science/article/pii/B9780128036785005142 Infection PreventionRichard Beers, in Anesthesia Equipment (Second Edition), 2013 Expanded PrecautionsExpanded precautions, also known as transmission-based precautions, are used in addition to standard precautions for patients with a known or suspected infection or colonization with either a highly transmissible or multidrug-resistant pathogen. For the anesthesia professional, knowledge of the management of patients with known or suspected infection with airborne and droplet pathogens is essential. Airborne transmission occurs when airborne droplet nuclei, fine particles less than 5 μm in diameter, disseminate infectious agents. Air currents suspend droplet nuclei and may carry them for long distances. For this reason, diseases spread by airborne droplet nuclei—measles, chickenpox, tuberculosis, smallpox, and severe acute respiratory syndrome (SARS)—are considered highly transmissible. Patients with known or suspected infection with airborne pathogens require specially designed facilities, equipment, and practices known as airborne infection isolation precautions.30,31 Routine care should be provided in rooms with special air handling and ventilation. Ambient air that contains infectious airborne droplet nuclei is removed from the room, so as not to enter other patient care areas, or it is circulated frequently through filtration capable of removing the infectious particles. Air-cleaning systems that use high-efficiency particulate aerosol (HEPA) filtration or ultraviolet germicidal irradiation (UVGI) technologies can be used in the room or surrounding areas to filter or decontaminate air evacuated from the patient’s room. During routine care of patients on airborne precautions, health care personnel must wear a properly fitted N95 mask (Fig. 20-15) for protection from infectious droplet nuclei that may be inhaled from the ambient air. The N95 designation indicates that the mask filters out 95% of airborne particles, as certified by the National Institute for Occupational Safety and Health (NIOSH). Barrier protection with gowns, gloves, and eye protection also is required. Droplets, not droplet nuclei, are generally larger than 5 μm and do not remain suspended in air currents. Droplets travel only a relatively short distance (~3 feet) from the source and infect others by depositing on the conjunctival, nasal, or oral mucosa. Therefore special air handling and ventilation are not required to prevent droplet transmission during routine care. Diseases generally transmitted through droplets include pertussis, viral influenza, and diphtheria. What is the most common means of transmission of infection in a healthcare facility?Contact transmission. The most common mode of transmission, contact transmission is divided into two subgroups: direct contact and indirect contact.
What is the major method of transmission of infectious disease?In direct transmission, an infectious agent is transferred from a reservoir to a susceptible host by direct contact or droplet spread. Direct contact occurs through skin-to-skin contact, kissing, and sexual intercourse. Direct contact also refers to contact with soil or vegetation harboring infectious organisms.
What are the 5 methods of disease transmission?The transmission of microorganisms can be divided into the following five main routes: direct contact, fomites, aerosol (airborne), oral (ingestion), and vectorborne. Some microorganisms can be transmitted by more than one route.
What is the most frequent cause of the spread of infection among institutionalized patients?Contact transmission. This is the most important and frequent mode of transmission in the health care setting. Organisms are transferred through direct contact between an infected or colonized patient and a susceptible health care worker or another person.
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