The infectious process is the interaction of microorganisms that cause disease with the environment and the host. Infection requires several elements:

The microbes or agents include anything that can cause communicable disease, such as bacteria, virus, fungi, protozoa (protists), or animals like worms. The source or reservoir for the microbe may be the patient, other people, or nonliving (inanimate) objects. Five main methods of transmission include contact, droplet, airborne, common vehicle, and vectors. Contact transmission may be direct or indirect (through an inanimate object). Common vehicle transmission includes items such as water, food, or contaminated equipment. Vectors or organisms that can spread the agent include mosquitoes, flies, rats, and other such vermin (pests). The host that does not have enough resistance to (i.e., is susceptible to) the infecting agent will become sick. Resistance may be lowered by poor nutrition, open wounds, invasive therapies such as an intravenous line, or a suppressed immune system. For infection to occur, all six of the elements of the infectious process must be present in order. The chain of infection or transmission can be broken and the infection prevented at any of the links (Fig. 3-1).

Infection is a reaction caused by a microorganism. Infection may be symptomatic or asymptomatic (i.e., with or without expression of health). A local infection is an infection limited to a small area of the body. A systemic infection is an infection located throughout the body. Infection may occur in a general or local manner. Signs and symptoms of a general infection include a fever, chills, pain, an ache or tenderness, a general feeling of tiredness, and night sweats. A local infection in a wound or incision may be characterized by redness, heat, swelling, pain, or fluid that is white, yellowish, or greenish.

In the past, isolation procedures and precautions were based on the patient’s diagnosis (Box 3-1). Someone with an infection was separated from others to prevent the spread of the microorganisms. In 1996 the Healthcare Infection Control Practices Advisory Committee (HICPAC) of the CDC established a two-level set of guidelines for isolation precautions designed for acute care hospitals. The two levels are Standard Precautions, which are applied to all patients, and Transmission-Based Precautions, which are applied to patients with known or suspected infections. These guidelines also may be applied to other health care delivery systems (Table 3-1).

Standard Precautions combine features of the previously used Universal Precautions and Body Substance Isolation guidelines. They are applied at all times to all patients and all body fluids except perspiration. They are designed to prevent transmission of HIV, hepatitis B virus (HBV), and other bloodborne pathogens when providing first aid or health care (Box 3-2). All body fluids of all patients are considered to be potentially infectious under the Standard Precautions guidelines. Body fluids that are included in the precautions include blood, semen, vaginal secretions, and tissues such as pleural, peritoneal, pericardial, cerebrospinal, amniotic fluids, and nonintact skin. Handling of feces, sweat, nasal secretions, urine, tears, and vomitus does not require Universal Precautions unless they contain visible blood. Contact with saliva only requires Standard Precautions when contaminated by blood and in the dental setting. Standard Precautions do not apply to breast milk except when contact is long such as in milk banking.

Protective barriers or personal protective equipment (PPE) used in the Standard Precautions include gloves, gowns aprons, masks, and protective eyewear. Gloves are worn when touching body fluids and when handling items or touching surfaces that are soiled with body fluids. They are changed after contact with each patient. The hands are washed immediately after removing gloves. PPE may also be worn when in contact with hazardous chemicals and some medicines. In some situations, protective hats and footwear may also be used. Disposable aprons, goggles, and masks are worn when there is the possibility of secretions splattering. The type of PPE used is determined by assessing the risk of transfer of microorganisms to and from the patient. Signs are placed outside the patient’s room to indicate which type of PPE is needed.

Prevention of injury from needles, scalpels, and other sharp devices is also included in the Universal Precautions. Needles should not be recapped or removed from syringes by hand. Sharp instruments such as needles and scalpel blades should be disposed of in puncture-resistant containers.

Case Study 3-1

While providing care for a patient, you find that someone has left an uncapped needle on the bedside tray. What should you do?

Case Study 3-2

You are using Transmission-Based Precautions to care for a patient. When care is completed, you notice that one of your gloves ripped sometime during the care. What should you do?