49 Infectious Disease Considerations for the Operating Room
THE TRANSMISSION OF INFECTION depends on the presence of three interconnected elements: a causative agent, a source, and a mode of transmission (Fig. 49-1). Understanding the characteristics of each element provides the practicing anesthesiologist with a methodologic aid to protect susceptible patients and health care workers and to avoid spreading infection.
There has always been concern about the transmission of infectious agents both to the patient from the anesthesiologist as well as from the anesthesiologist to the patient.1 In addition, there are many sites within the hospital environment where moist or desiccated organic material with the ability to host potentially pathogenic microbes may survive for extended periods of time (Table 49-1)2,3; some may even resist the usual cleaning and disinfection techniques.4 Their transmission from the source to the host may occur via indirect nonapparent mechanisms (e.g., most commonly through hand contact).
TABLE 49-1 Nosocomial Pathogens and Environmental Contamination
| Pathogen | Types of Environmental Contamination | Organism Survival Time |
|---|---|---|
| Influenza virus | Aerosolization after cleaning; fomites | 24-48 hours on nonporous surfaces |
| Parainfluenza virus | Clothes and nonporous surfaces | 10 hours on nonporous surfaces; 6 hours on clothes |
| Norovirus | Extensive environmental contamination, possible aerosolization | ≤14 days on fecal specimens, ≤12 days on carpets |
| Hepatitis B virus | Environmental contamination with blood | 7 days |
| Coronavirus-SARS | Possible results from emergency department specimens; super-spreading events | 24-72 hours on fomites and fecal specimens |
| Candida | Fomite contamination | 3 days for Candida albicans and 14 days for Candida parapsilosis |
| Clostridium difficile | Extensive environmental contamination | 5 months on hospital floors |
| Pseudomonas aeruginosa | Drain sink contamination | 7 hours on glass slides |
| Acinetobacter baumannii | Extensive environmental contamination | 33 hours on laminated plastic surfaces |
| MRSA | Extensively contaminated burn units | ≤9 weeks after drying; 2 days on laminated plastic surfaces |
| VRE | Extensive environmental contamination | ≤58 days on working surfaces |
MRSA, Methicillin-resistant Staphylococcus aureus; VRE, vancomycin-resistant enterococci.
Modified from Hota B. Contamination, disinfection, and cross-colonization: are hospital surfaces reservoirs for nosocomial infection? Clin Infect Dis 2004;39:1182-9.
Host
Methods of Transmission
Air Transmission
Droplets
Droplet contamination is considered a direct transmission of organisms because there is a direct transfer of microorganisms from the colonized or infected person to the host. This generally occurs with particles whose diameters are greater than 5 µm that are expelled from an individual’s mouth or nose, mainly during sneezing, coughing, talking or during procedures such as suction, laryngoscopy, and bronchoscopy (Fig. 49-2). Transmission occurs when the microorganism-containing droplets, expelled or shed by the infected person (source), are propelled a short distance (usually not exceeding 60 cm or about 2 feet through the air) and deposited on the host’s conjunctivae or oral or nasal mucous membranes. When a person coughs, the exhaled air may reach a speed of up to 965 km/hr (600 mph).5 However, because the droplets are relatively large, they tend to descend quickly and remain suspended in the air for a very brief period, thus obviating the need for special handling procedures for the OR air. Examples of droplet-borne diseases include influenza, respiratory syncytial virus, severe acute respiratory syndrome (SARS), and others commonly found in droplets from the respiratory tract.
Droplet Nuclei
Droplet nuclei result from the evaporation of droplets while suspended in the air. Unlike droplets, the nuclei have an outer layer of desiccated organic material and a very small diameter (1 to 5 µm) and remain suspended in air indefinitely. The microorganisms contained within these nuclei may be spread by air drafts over great distances, depending on the environmental conditions (dry and cold atmosphere, with limited or no exposure to sunlight favoring the spread).6 In contrast to droplets, which are deposited on mucous membranes, droplet nuclei may enter the susceptible host by inhalation; examples of droplet nuclei–borne diseases include tuberculosis, varicella, and measles.
Contact Transmission
Direct Contact
This type of disease transmission involves direct physical contact between two individuals. The physical transfer of microorganisms from an infected or colonized person to a susceptible host may occur from child to health care provider or from health care provider to child during professional practice (e.g., venous cannulation, laryngoscopy, burn care, or suction of secretions). Health care providers working in the OR may be exposed to skin contamination by body fluids. This is an issue of grave concern because of the potential exposure of health care providers to patients with unrecognized infections, especially hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV). Hepatitis B is a highly infectious virus that requires a small amount of blood (10−7 to 10−9 mL) to transmit the disease. The incidence of skin contamination of anesthesiologists and related personnel by blood and saliva is substantial. One study examined 270 anesthetic procedures during 7 consecutive days. The blood of 35 patients (14%) contaminated the skin of 65 anesthesiologists in 46 incidents. Of these contamination events, 28 (61%) occurred during venous cannulation. Of anesthesiologists who had been contaminated by blood, 5 of 65 (8%) had cuts in the skin of their hands.7 The importance of this observation is that seroconversion of health care providers has been reported after skin contamination by infected blood from HIV carriers8 and HBV infection after blood splashing into health care workers’ eyes.9 Scabies, pediculosis, and herpes simplex are among the diseases most frequently transmitted by direct contact.10–17 These studies explain why meticulous hand washing and routine use of barriers such as gloves and eye protection are such an important part of protecting ourselves even during routine procedures such as starting an IV line or performing laryngoscopy.18
Indirect Contact
Indirect contact involves the transmission of microorganisms from a source (animate or inanimate) to a susceptible host by means of a vehicle (e.g., an intermediary object) contaminated by body fluids. Tables 49-2 and 49-3 provide examples of diseases associated with bodily fluids to which health care workers may be exposed. The vehicle for transmission may be the hands of a health care provider who is not wearing gloves or a provider who fails to wash his or her hands after providing care to a child.19–22 This type of contact can also come from health care providers who touch (with or without gloves) contaminated monitoring or other patient care devices (e.g., blood pressure cuffs, stethoscopes, electrocardiographic cables, or ventilation systems [respirators, corrugated tubes, Y pieces, valves]), which are used with several children without proper cleaning or disinfection between each use.23–25
| Body Fluid | Disease Transmitted |
|---|---|
| Blood | HBV, HIV, HCV, CMV, EBV, NANBH |
| Seminal fluid | HIV, HBV, CMV |
| Vaginal discharge | HIV, HBV, CMV |
| Saliva and sputum | HSV, TB, CMV, respiratory diseases |
| Cerebrospinal fluid | Encephalopathic organisms (see Table 49-5), HIV |
| Breast milk | HIV, HBV, CMV |
| Urine | CMV, EBV, HBV |
| Feces and intestinal fluid | HAV, gastrointestinal diseases (see Table 49-5) |
CMV, Cytomegalovirus; EBV, Epstein-Barr virus; HAV, hepatitis A virus; HBV, hepatitis B virus; HCV, hepatitis C virus; HIV, human immunodeficiency virus; HSV, herpes simplex types I and II; NANBH, non-A, non-B hepatitis; TB, tuberculosis.
Modified with permission from Browne RA, Chenesky MA. Infectious diseases and the anaesthetist. Can J Anesth 1988;35:655-65.
TABLE 49-3 Infectious Agents That May Be Found in the Operating Room
Viruses: hepatitis A virus, rotavirus, adenovirus, enterovirus
Bacteria: Giardia,* Cryptosporidium, Isospora*
Viruses: Human immunodeficiency virus,* herpes simplex virus,* Epstein-Barr virus*
*Opportunistic infections in immunocompromised patients, especially those with acquired immunodeficiency.
Modified with permission from Browne RA, Chenesky MA. Infectious diseases and the anaesthetist. Can J Anesth 1988;35:655-65.
There are also reports of equipment, fomites, and drugs (mainly propofol) that have resulted in hospital-acquired infections.14,26–44 However, many of the following situations could potentially cause an infection:
Up to 40% of the anesthetic equipment in the OR that was in direct or indirect contact with the child (blood pressure cuffs, cables, oximeters, laryngoscopes, monitors, respirator settings, and horizontal and vertical surfaces) may be contaminated with blood because of inadequate cleansing procedures between uses.2,3,23,45,46
In some institutions, up to 8% of the Bain circuits that were reused without previous sterilization were contaminated.47
Contamination of syringe contents has occurred with glass particles during ampule opening, which in turn may compromise the sterility of the contents, presumably because of the passage of bacteria contained on glass particles into the solution.48–50
IV tubing has a significant blood contamination rate as well as contamination by blood from syringes used to inject medications. This can occur with the absence of visible blood reflux in the tubing or syringe. Simply replacing the needle on a syringe that will be reused is ineffective in preventing cross-infection. The only certain strategy to prevent infection is to not use the same syringe in multiple patients.51
Refilling both glass and plastic syringes several times has been shown to result in contamination of the contents; single use is therefore recommended.51,52
Some drug formulations, especially propofol, can sustain bacterial growth under certain conditions. Thus great care should be given to aseptic technique when transferring drugs from the vial to a syringe and to use the contents of the syringe within 4 hours.53–57
Needles that had been used for spinal or epidural anesthesia were found to be contaminated with coagulase-negative staphylococci (15.7%), yeasts (1.5%), enterococci (0.8%), pneumococci (0.8%), and micrococci (0.8%), suggesting that despite standard skin preparation and cleansing there may be a significant rate of needle contamination.58 It is unclear whether these skin organisms can be transmitted and cause an infection during administration of a neuraxial block.
Blood and saliva frequently contaminate the skin of anesthetic personnel during routine anesthetic practice.7
Violations of contemporary guidelines for preventing infections (e.g., hand-washing, wearing gloves, surgical masks, ocular protection, scrubs, or syringe reuse) by anesthesiologists are frequent.18 Anesthesia staff are aware that they work in a potentially infectious environment, but whether they adopt the protective measures to prevent infections in both themselves and their patients is quite variable (11% to 99%).23,59–61
Accidents with Cutting or Piercing Devices
Percutaneous contamination as a result of a cutting or piercing accident is the most effective means to transmit bloodborne pathogens. Evidence suggests that this is the main route of HIV, HBV, and HCV infection,62–64 especially if the injury is caused by hollow-bore needles that were used to draw blood or establish IV access.65,66 Over 20 other bloodborne pathogens have been transmitted by this means, including those causing herpes, malaria, and tuberculosis.67 The infectious risk after a percutaneous exposure to blood or body fluids from an HIV positive person is approximately 0.3%. Among health care providers lacking protective antibodies, the risk of HBV infection after an injury with a cutting or piercing device contaminated with hepatitis B antigen is approximately 37%; in the case of HCV it is approximately 1.8% (range 0% to 7%). Anesthesia staff lacking HBV protective antibodies are at great risk for acquiring the disease.68,69 These infection rates underscore the need for the use of “safe” needles and the need to advocate the use of “needleless” systems even though they are significantly more expensive. This also emphasizes the need for meticulous handling and disposal of needles and other sharp instruments as well as the use of special “sharps boxes” designed to minimize accidental needle sticks (e.g., “mail box” type boxes that do not allow the hand to enter the disposal area).70–85 The U.S. Centers for Disease Control and Prevention (CDC) has estimated that in the United States there are approximately 385,000 cutting and piercing accidents annually among health care providers in hospitals; 25% of these occur in the OR.67 However, the actual prevalence is thought to be much greater, because many of these events are unreported. The distribution of these accidents among anesthesiologists is shown in Figure 49-3, A; the distribution of the items most frequently associated with cutting and piercing injuries in health care providers is shown in Figure 49-3, B. Should such an accident occur (e.g., needle puncture, exposure to nonintact skin, or mucous membrane exposure) there are now specific recommendations regarding immediate assessment of risk, assessment of the exposure source (chart review, inform the patient that an accident has occurred and ask permission to determine HBV, HCV, and HIV serologic status) and initiation of appropriate treatment of the health care worker. It is advised to obtain as much information regarding the patient as possible, if the patient is known, to obtain a sample of blood from the patient for determination of potential carrier state (Table 49-4), and to report to the health service for immediate institution of prophylaxis and follow-up (Table 49-5), especially for HIV exposure (Tables 49-6 and 49-7).
TABLE 49-4 Recommendations for the Contents of the Occupational Exposure Report
• Details of the procedure being performed, including where and how the exposure occurred; if related to a sharp device, the type and brand of device; and how and when in the course of handling the device the exposure occurred
• Details of the exposure, including the type and amount of fluid or material and the severity of the exposure; for example, for a percutaneous exposure, depth of injury and whether fluid was injected and for a skin or mucous membrane exposure, the estimated volume of material and the condition of the skin (e.g., chapped, abraded, intact)
• Details about the exposure source (e.g., whether the source material contained hepatitis B virus, hepatitis C virus, or human immunodeficiency virus; if the source is infected with human immunodeficiency virus, the stage of disease, history of antiretroviral therapy, viral load, and antiretroviral resistance information, if known)
• Details about the exposed person (e.g., hepatitis B vaccination and vaccine-response status)
• Details about counseling, postexposure management, and follow-up
Modified with permission from Updated U.S. Public Health Service guidelines for the management of occupational exposures to HBV, HCV, and HIV and recommendations for postexposure prophylaxis. MMWR Recomm Rep 2001;50:1-52. Available at www.cdc.gov/mmwr/PDF/rr/rr5011.pdf
TABLE 49-5 Factors to Consider in Assessing the Need for Follow-up of Occupational Exposures
HBsAg, Hepatitis B virus surface antigen; HBV, hepatitis B virus; HCV, hepatitis C virus; HIV, human immunodeficiency virus.
