Introduction to Microbiology (Safety in the Healthcare Facility) (Nursing) Part 3

Drug-Resistant Microorganisms

Effective antimicrobial therapy normally destroys or significantly reduces the number of microorganisms that cause disease. These medications allow the body’s natural defenses to take over and fight the unwanted microorganisms. However, certain microorganisms, including bacteria, viruses, fungi, and parasites, have a tendency to evolve resistant strains to existing medications. The development of antimicrobial-resistant microorganisms occurs in several ways. The most common way occurs when antimicrobial therapy is unnecessary or incomplete, allowing some invading microorganisms to survive. These microorganisms have the ability to transfer their resistance to future generations. Therefore, future antimicrobial therapy may be ineffective. These resistant organisms are transmitted into the environment through coughing, sneezing, and direct contact. Chances are that more drug-resistant microorganisms will develop. Individuals at greatest risk are people who have immune systems that are not strong, better known as compromised immune systems. These individuals have difficulty protecting their bodies from infections and destroying drug-resistant microorganisms.

To help prevent the development of drug-resistant microorganisms and the spread of disease, you can take several measures. It is important to teach these measures to your clients as well:

•    Take antimicrobial drugs only as prescribed and only if absolutely necessary.


•    Take antimicrobial drugs for the entire period prescribed, even if symptoms of illness disappear.

•    Do not share antimicrobial drugs with others or take their “leftover medications.”

•    To avoid development of resistant strains, discuss the necessity of antibiotics for mild infections with your healthcare provider.

•    Do not use antibiotics for viral infections.

NCLEX Alert Factors leading to the development of drug-resistant microorganisms may be included in the examination. You may be required to know which medications are appropriate, topics regarding client and family teaching, or methods of wound care.

Infections known as MRSA and healthcare-associated MRSA (HA-MRSA) have become a serious concern in healthcare facilities. Staphylococcus aureus is an organism normally found on the skin of healthy people and is not normally pathogenic. However, in certain situations, it is considered opportunistic and becomes pathogenic. That is, it will cause illness in a person with a compromised immune system or an open wound. (The organism is “pathogenic” only to that person.) In addition, this organism produces a substance called ß-lactamase, which degrades penicillin.

The organism MRSA (methicillin-resistant Staphylococcus aureus) or HA-MRSA is also known as a “superbug.” The organism has become resistant to certain antibiotics. These include methicillin, as well as some of the more common antibiotics, such as penicillin, amoxicillin, ampicillin, erythromycin, and ciprofloxacin. “Staph” infections, including MRSA, occur most frequently in healthcare facilities, thus the name HA-MRSA. People with MRSA who have not been hospitalized or who have not had an invasive medical procedure within the past year are said to have CA-MRSA, or community-associated MRSA.

HA-MRSA is today’s most prevalent nosocomial illness or infection, one originating in a healthcare facility. Most of the cases involve skin or soft tissue infections, such as an abscess or cellulitis. The major route of transmission is via contaminated hands of healthcare workers.

Key Concept The most important factor in preventing the spread of MRSA is careful handwashing. Other means are also used, such as the wearing of gloves and, in some cases, isolation.

TABLE 40-2. Common Pathogenic Viruses

DISORDER GROUP

NAME

COMMON DISORDERS CAUSED

COMMENTS

Internal disorder producers

Picornavirus (enteric group) Poliovirus

Poliomyelitis

At least three types

Echovirus

ECHO syndrome (enteric cytopathogenic human orphan), aseptic meningitis, diarrhea neonatorum, paralytic disease

Vaccine available At least 30 types No vaccine

Picornavirus (rhinovirus group) Coxsackievirus

Common cold, upper respiratory infections Aseptic meningitis, myocarditis, pericarditis

No vaccine At least 30 types No vaccine

Rash producers

Poxvirus

Smallpox

Possibly eradicated; may be used as a bioterrorism weapon

Rubella virus

German measles (rubella)

Vaccine available Can cause birth defects Vaccine available

Rubeola virus

"Red” measles (rubeola), encephalomyelitis

No vaccine

Erythema infectiosum

"Fifth” disease

Vaccine available

Varicella zoster (herpes zoster)

Chickenpox (varicella), shingles (herpes zoster)

Herpesvirus simplex

Cold sores (herpes simplex)

No vaccine

Herpesvirus type II

Herpes labialis (genital herpes), encephalitis, vulvovaginitis

Two types No vaccine

Roseola infantum virus

Roseola infantum ("rose rash,” exanthem subitum)

Genital warts

Condylomata acuminata

Human papillomavirus (HPV) infection

Vaccine available

Respiratory disorder producers

Influenza virus (myxovirus types A, B, C)

Influenza ("flu,” grippe), croup, pneumonia

Three types

Vaccine available (moderate effectiveness)

Mumps virus (paramyxovirus) Infectious mononucleosis virus (Epstein-Barr virus) Adenovirus

Parotitis (mumps), orchitis (inflammation of testes), meningoencephalitis Infectious "mono”

Conjunctivitis

Vaccine available No vaccine

Chronic (latent) disorder producers

Hepatitis Type A

Type A hepatitis (formerly called infectious hepatitis)

Vaccine available

Type B ("Dane particle”)

Type B hepatitis (formerly called serum hepatitis)

Vaccine available

Type C (non-A, non-B)

Type C hepatitis (parenterally transmitted)

No vaccine

Type D

Type D hepatitis (can be coinfection with type B)

Type E

Type E (transmitted by fecal-oral route)

Papovavirus

Warts (verrucae)

Arbovirus

Group A

Equine encephalitis

Vaccine possible

Group B

Yellow fever

Vaccine possible

Diplovirus

Colorado tick fever

No vaccine

Rabies virus (rhabdovirus)

Rabies (hydrophobia)

Vaccine available

Autoimmune disorder producers

Human immunodeficiency virus (HIV)

Opportunistic infections, such as Pneumocystis pneumonia and Kaposi’s sarcoma Can develop into full-blown acquired immunodeficiency syndrome (AIDS)

Virus has been identified No vaccine available Transmitted via body fluids, especially blood and semen

Nosocomial infection risk factors for clients in healthcare facilities include:

•    A compromised immune system owing to conditions/situations such as AIDS, cancer, aplastic anemia, chemotherapy, radiation, or overproduction of corticosteroids (Cushing disease)

•    A break in the skin following situations, such as surgery or a burn

•    The presence of a central or peripheral intravenous catheter

•    Invasive medical procedures, such as urinary catheterization, dialysis, tracheostomy, or colonoscopy

•    Serious underlying disorders, such as chronic kidney disease, diabetes, peripheral vascular disease, and dermatitis or other skin lesions

•    Previous exposure to antimicrobial drugs, reducing the normal flora of the body and giving the opportunistic organism an advantage

•    Repeated hospitalizations, thus increasing exposure

•    Very old age or very young age, increasing vulnerability

•    Previous infections by multi-drug-resistant organisms

Organisms that commonly cause nosocomial infections include:

•    MRSA—methicillin-resistant Staphylococcus aureus

•    VRE—vancomycin-resistant enterococci

•    ESBLs—extended-spectrum ß-lactamases (resistant to cephalosporins and monobactams)

•    pRsp—penicillin-resistant Streptococcus pneumoniae, which causes pneumonia, often in older people

•    EMRSA—epidemic MRSA

Recently, attention has been given to the spread of another type of drug-resistant infection, carbapenem-resistant Klebsiella pneumoniae (CRKP). Klebsiella bacteria are found normally in the gastrointestinal system, but they can lead to infections, such as pneumonia, in hospitalized clients, especially those receiving treatments with invasive devices such as ventilators or central venous catheters. Elderly or severely debilitated people are particularly vulnerable. Another such organism is NDM (New Delhi metallo-beta lactamase). Prevention of transmission of CRKP or NDM is important because of their extensive drug resistance.

INFECTIOUS DISEASE

An infection is a condition in which pathogens invade the body. Diseases caused by pathogenic microorganisms are called infectious diseases. The microorganisms increase in number and produce the symptoms of illness. Microbiologists use the term etiology to describe the specific cause of a disease. Many diseases caused by microorganisms are communicable, meaning they can spread from one person to another. Contagious diseases are communicable diseases that are transmitted to many individuals quickly and easily. When a large number of people in the same area are infected in a relatively short time, the disease is said to be epidemic.

Chain of Infection

Communicable diseases spread easily. Scientists and healthcare workers use knowledge gained in epidemiology (the study of ways by which diseases are transmitted to people) to develop methods for preventing the spread of microbial infections. The Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia, is dedicated to the study of pathogens and the control of communicable diseases. Disease will spread if the chain of infection is unbroken (Fig. 40-6). The chain of infection contains the following elements:

•    Pathogenic microorganism

•    Reservoir in which the pathogenic microorganism can live and grow

•    Portal of exit from which the microorganism can leave the reservoir

•    Vehicle to transmit the organism

•    Portal of entry through which the microorganism can enter the host

•    Susceptible host in which the microorganism can find a reservoir

Some of these elements are controllable and some are not. The following sections discuss each component of the chain of infection and measures you can take at each stage to break the chain.

Reservoir

Because pathogenic microorganisms exist everywhere, the reservoir is any place where the microorganism can survive before moving to a place where it can multiply. Reservoirs may be living beings (e.g., people, domesticated or wild animals, and insects) or inanimate objects (e.g., air, soil, food, fluids, bedding, and utensils).

Healthcare personnel can break the chain at this point by destroying the microorganism or retarding its growth through the following measures:

•    Sterilizing instruments and dressings used in the operating room and elsewhere

•    Disinfecting floors and equipment

•    Using bedpans or other personal items for one client only

•    Discarding disposable equipment (e.g., thermometer probe covers, catheters) in appropriate receptacles after use; discarding other equipment, such as bedpans, urinals, and water pitchers, when the client is discharged

•    Giving baths using soap and water or a special disinfectant solution, to remove drainage and dried secretions

•    Changing dressings promptly when they become wet as per physician’s order

•    Placing contaminated articles, such as dressings, tissues, or linen, in moisture-proof bags; using red, specially labeled biohazard bags when indicated

•    Discarding contaminated needles and syringes and other sharps in the appropriate moisture-resistant, puncture-proof container—never throw them in the waste container or put your fingers inside the sharps container!

•    Making sure drainage tubes and collection bags drain properly, and emptying them according to agency policy

•    Never using any sterile package that has become wet or has a broken seal

•    Using personal protective equipment as needed.

•    Thoroughly wash or sanitize hands often

In addition, healthcare personnel should not work when they might be a source of infection to clients.

Portal of Exit

Microorganisms must have a means of escape from their reservoir. Portals of exit in the human body include all body orifices (openings). Microorganisms may leave the body in any of its natural discharges: sweat, mucus, semen, sputum, saliva, urine, or feces. They may also leave the body in vom-itus, drainage, or blood from breaks in the skin.

You can break the chain of infection and prevent microorganisms from escaping with thorough handwashing, appropriate waste disposal, and careful management of secretions and drainage. Avoid talking, sneezing, or coughing directly over open wounds or a sterile field. Always wear gloves when potential contact with body secretions exists. Clients who have airborne infections may need to wear masks or receive ordered medications that prevent coughing. Follow infection control protocols carefully.Some clients must be isolated to prevent the spread of infection.

Vehicle of Transmission

Microorganisms are transmitted by several means (Table 40-3). Direct contact usually involves the spread of pathogens from one person to another through body contact, such as touching, shaking hands, kissing, or sexual intercourse.

The cyclic process through which an infection occurs. To prevent a disease from spreading, the chain of infection must be broken by means such as those listed here.

FIGURE 40-6 · The cyclic process through which an infection occurs. To prevent a disease from spreading, the chain of infection must be broken by means such as those listed here.

TABLE 40-3. Transmission of Infectious Disease

TYPE OF TRANSMISSION

EXAMPLES OF METHODS

Direct or indirect contact

Touching, kissing, shaking hands, sexual intercourse

Airborne

Dust particles and spores in the air, droplets from sneezing

Foodborne

Spoiled and uncooked food, food contaminated with feces or soil

Waterborne

Feces-contaminated water supply

Vectors

Bites by infected insects, dogs, cats, rodents

Contaminated articles

Dishes, bedding, needles, syringes

Bloodborne

Transfusions, kidney dialysis, injections, accidental needle stick

Many infectious diseases are spread in this fashion. Indirect contact implies that an intermediary object harbors the microorganisms and carries them from an infected person to a new victim. Common intermediaries found in healthcare settings include bedding, used tissues, used syringes, drinking cups, and dressings. A human carrier does not exhibit the symptoms of a disease, but carries the pathogens and transmits them to others.

Airborne transmission of an infectious disease is accomplished by dust or moisture particles carrying microbes or spores that blow from place to place. For instance, infectious diseases can be transmitted by pathogen-containing moisture drops—produced by sneezing or coughing—that are propelled far from the carrier. Common colds and other upper respiratory infections are easily spread by droplet infection. Desert fever is carried by dust particles.

Public water supplies contaminated with bacteria will produce waterborne transmission of diseases. Food poisoning can result from eating foods that have been improperly refrigerated or cooked. The spread of pathogens in this fashion is called foodborne transmission.

Living carriers of pathogens are called vectors. Mosquitoes, flies, fleas, ticks, and lice are the most common vectors that transmit diseases to human beings. These vectors spread disease by transferring microorganisms from their feet, wings, or bodies to food, which a person eats, unaware that the food is contaminated. Another method of disease spread occurs when vectors become infected themselves and bite or sting a victim, who then also becomes infected.

To break the infection chain at the vehicle of transmission level, burn all trash in non-residue incinerators. Remove linen without shaking it or allowing it to touch your clothing. Carefully cover all infected wounds. Properly handle and prepare food. Healthcare facility measures include isolation of clients with contagious diseases, sterilization of reusable equipment and supplies, proper disposal of wastes and trash, and control of airflow. Be aware of how specific diseases are spread. For example, tuberculosis (TB) is spread through the air; thus, when treating clients with TB, you should use airborne precautions. If a client has a disease that can spread through body excretions, disinfecting the toilet after use or having the client use a toilet in a separate room may be necessary. All urine and feces must be carefully disposed of and bedpans and urinals carefully cleaned. Use syringes and needles safely. Do not recap or attempt to break needles. A needlestick from a contaminated needle can spread disease to the nurse. In all healthcare settings, clients should have their own set of personal care items. Sharing items, such as bedpans, urinals, and eating utensils, can lead to the transmission of infection.

Key Concept Handwashing is the single most basic way to prevent the transmission of pathogens. Wash or sanitize your hands often.

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