Medical Asepsis and Infection Control

Medical Asepsis & Infection Control

• Medical asepsis is the focus of module 5.

Microbial World

• Anton van Leeuwenhoek first observed "wee animalcules" with a microscope.
• Major causes of death in the U.S. in the 21st century included microbial infections like pneumonia, tuberculosis, gastroenteritis, and diphtheria.

Key Infections

• Pneumonia involves lung inflammation with air sacs filling with inflammatory cells, leading to solid lungs.
• Tuberculosis is caused by Mycobacterium tuberculosis and identified by Koch. Nodular lesions form in the tissues.
• Gastroenteritis is an inflammation of the stomach and intestine caused by viruses, bacteria, or food-poisoning toxins that cause vomiting and diarrhea and lasts 3-5 days. IV fluids may be needed if there is severe fluid loss.
• Diphtheria is caused by Corynebacterium diphtheria and is a contagious infection marked by sore throat, weakness, and mild fever, with a 2-6 day incubation period. It generally affects the throat, and sometimes other mucous membranes spread from direct contact or contaminated milk.

Microbes and Infections

• Microbes recycle organic/inorganic matter, scientists study characteristics to control/utilize safely.
• Diseases caused by microorganisms growing in or on a host organism are known as infections.
• Infection involves the establishment and growth of microorganisms in or on their host.
• A disease results when an infection injures the host.
• Pathogenic microorganisms cause infectious diseases.

Pathogen Action & Exotoxins

• Pathogens multiply, cause tissue damage, and secrete exotoxins.
• Exotoxins produce side effects like high fever, nausea, vomiting, or shock

Four Basic Infectious Agents

• The four basic infectious agents include: bacteria, viruses, fungi and protozoan parasites.

Bacteria

• Bacteria are prokaryotic, with no nuclei or membrane-bound organelles.
• Eukaryotes have a true nucleus.
• Metabolic activity occurs on the cytoplasmic membrane.
• Prokaryotes cannot ingest particulates or liquid droplets.
• Bacteria are often found grouped in colonies, and each colony comes from a single cell.
• Classification is based on bacteria morphology, biochemistry & genetic constitution.

Bacterial Morphology & Endospores

• Morphology (size and shape) is key for classifying bacteria, often using Gram staining.
• Medically important bacteria have three morphologies: cocci (spheres), bacilli (rods), and spirals.
• Endospores are dormant structures highly resistant to external environments.
• Spores resist chemical and physical agents and germinate when conditions are right.
• The ‘ENDOSPORE’ is a survival form produced by bacteria.
• Bacillus and Clostridium are the only genera of bacteria able to produce endospores and are of medical importance.

Common Bacterial Infections

• Some common bacterial infections are streptococcal pharyngitis, Klebsiella pneumonia infection, and Clostridium botulinum infection.
• Klebsiela pneumonia infection is associated with pneumonia and respiratory infections.
• Clostridium botulinum grows in poorly preserved canned food, producing a toxin that causes serious food poisoning.

Viruses

• Viruses are simpler than bacteria or animal cells and are obligate intracellular parasites.
• Viruses need a host cell for survival since they cannot make specific proteins.
• Viruses possess either deoxyribonucleic acid (DNA) or ribonucleic acid (RNA), surrounded by a protein coat (capsid).
• Chemical nature, size, and symmetry generally characterize a virus.
• Viral infections may remain dormant and reemerge, causing a latent or dormant infection, such as a cold sore from herpes simplex virus.
• Common human viral diseases include the common cold (rhinovirus), infectious mononucleosis (Epstein Barr), and warts (papillomavirus).
• Nucleic acids in viruses are single/double stranded & positive/negative stranded.
• Nanometer Viruses range in size from 20nm-250nm. An electron microscope is needed for visualization since 1nm = 10⁻⁹m.

The Process of Infection

• Incubation Stage: Pathogen enters and may lie dormant, begins to produce nonspecific symptoms.
• Prodromal Stage: More specific symptoms appear, the microorganisms increase, and the disease is highly infectious.
• Full Disease Stage: Symptoms reach full extent or are vague; still highly infectious.
• Convalescent Stage: Symptoms diminish/disappear, diseases may go into a latent phase, like with malaria, tuberculosis, and herpes.

Fungi

• Fungi can be macroscopic or microscopic, including mushrooms, puffballs, yeast, and mold.
• Fungi are eukaryotic with a nucleus and membrane-bound organelles.
• Fungi intracellular organelles are seen inside a fungal cell distinct from bacteria.
• Fungal is also much larger than bacteria.
• Fungal cell membranes have a different sterol than animal cells, which have cholesterol.
• Medically important pathogenic fungi are dimorphic: they can grow as single-celled yeast or filamentous hyphae (mold).
• The form fungi take depends on growth conditions.
• Fungi are classified by the type or method of sexual reproduction.

Molds & Fungal Infections

• Molds have tiny branches where spores called conidia form.
• Conidia are lightweight, resistant to drying, easily dispersed to new locations.
• Fungal diseases are classified into four different categories.

Types of Fungal Infections

• Superficial infections alter skin color. Tinea Nigra creates painless black/brown discoloration on hands/feet.
• Cutaneous infections are the cutaneous infections, which involve the keratinized tissues of the hair, nails, and skin. Tinea pedis, or "athlete's foot," is a common clinical infection in this group.
• Ringworm is a fungal growth pattern.
• Subcutaneous fungal infections enter the host through trauma to the skin.
• Systemic infections enter circulatory and lymphatic systems, and can be fatal.

Protozoan Parasites

• Classification is based on motility. One group is classified by amoeboid locomotion.
• Few amoebas are pathogenic.
• Motility in the second group is facilitated via long flagella/protein tail.
• Third group moves with short protein tails or cilia.
• Sporozoans are nonmotile and don't form spores like bacteria/fungi.

Other Protozoan Information

• Protozoa can form cysts for survival outside of a host.
• Cysts resist chemical and physical changes.
• Trichomonas vaginalis (STD) and Plasmodium vivax are typical protozoan infections.

Establishing Infectious Diseases

• There are six steps to establishing diseases.
• These are: encounter, entry, spread, multiplication, damage, and outcome.

Encountering Infections

• Encounter has infectious organisms contact its host.
• The reaction to the microbes varies greatly.
• Mothers' wombs are sterile and the placenta is a selective barrier, yet congenital infections like rubella and syphilis can still occur.

Entry of Infections

• Most of the body has contact with the external environment.
• The digestive, biliary, urinary, and respiratory systems are directly connected to the exterior. The peritoneal cavity in women is exposed via the fallopian tubes.
• Microbes enter via ingression (toxins) or penetration (flagella, vectors, cuts/wounds).
• Ingression doesn't involve tissue penetration
• It involves microbes that stick to the host cell surface secreting toxins, like diarrhea.
• The respiratory system can be invaded with contaminants. Penetration is when bacteria causes syphilis.

Spreading Infections

• Spread of infectious organisms can occur before or after multiplication.
• The immune system defenses are the main barrier.
• Site of entry and human anatomy determine how the microbe spreads.
• Viruses that cause the common cold spread through coughing and sneezing.

Multiplying Infections

• The number of microbes is too small to cause symptoms initially.
• Most agents must multiply first to be recognized.
• Incubation is between when host defenses are overcome and a substantial population is reached.

Infection Damage

• Infectious agents can cause damage either directly or indirectly.
• That may be cell death from toxins secreted by infectious agents.
• Exponential microbe growth may obstruct organ systems.
• Microbes may indirectly damage a host by altering the metabolism of the host.
• Life threatening infections result, and death can follow within hours due to toxins, such as with botulism.

Infection Outcomes

• Hosts gain control of infectious agents.
• Infectious agents overcome host’s immunities
• Hosts & infectious agents reach symbiotic compromises

Chain of Infection

• In 1876, Robert Koch introduced the germ theory which had the following tenets: specific organisms cause specific diseases and a series of events must occur to transmit a disease from an infected person to an uninfected person.
• Disease spreads via unknown entity or contagion.
• The disease is contagious.
• The four factors involved with Koch in spreading disease are: host, infectious agent, mode of transmission, and reservoir.

Human Hosts & Infectious Microorganisms

• Human hosts provide nutrients/metabolites that support microbial growth.
• Regions of the human body offer distinct temperature, pH, or body fluid for microbial growth.
• Infectious microorganisms include bacteria, viruses, fungi, and protozoa.

Modes of Transmission

• Mode of transmission can be exogenous (outside the body) or endogenous (inside the body).
• Exogenous acquired diseases come from pathogens in the environment by the following:
  • direct contact
  • indirect host-to-host contact
  • vectors
  • fomites.

Host-to-Host Transmission, Flora

• Host-to-host transmission occurs via handholding, coughing, sexual contact, and touching, and is also aided by a liquid medium. Liquid mediums include:
  • secretions
  • phlegm
  • sneeze
  • cough
  • urine
  • feces.
• Endogenous transmission comes from encounter with microorganisms inside the body.
• Flora, a.k.a. the human flora, refers to the microbial community on a healthy person that reside on the surface and in deep layers of skin, in the saliva and oral mucosa, in the conjunctiva, and in the gastrointestinal tracts.
• The human flora consists of bacteria, fungi, and archaea.
• There are between 500-1,000 species of bacteria live in the human gut and the skin.
• Examples are:
  • Escherichia coli = lives in the colon
  • Actinomyces viscosus = lives in the mouth
  • Lactobacillus iners / I. crispatus = lives in the vagina.

Reservoir & Typhoid Mary

• A reservoir is where the infectious organism lives and allows for the potential transmission of the organism.
• The reservoir is a carrier that is an infected person that shows no disease symptoms.
• They be: -person -animals -inanimate (lifeless) objects.
• An example of a human person would be typhoid Mary, (Mary Mallon) who was a carrier of Salmonella typhi and died in '38. Other examples, such as cow, help obliterate pathogens. Insets, dusty corners, contaminated linens, and food may also be reservoirs.

Nosocomial Infections

• 5% of all hospital patients acquire an additional condition.
• It is a hospital acquired condition.
• The Latin term for hospital is called Nosocomium.
• Iatrogenic infection results from medical intervention.
• Sources include personnel, flora, contaminated environments, bloodborne pathogens, and invasive procedures.

Encouraging Nosocomial Infections

• Encouraging factors include:
  • environment
  • infectious agents via air contamination, visitors, food/instruments, personnel
  • therapeutic regimen with cytotoxic drugs, altered flora from antimicrobials, and hospital bacteria for equipment
  • contaminated items such as catheters or unclean and unsterilized equipment
  • during dressing changes and invasive procedures.

Increasing the Potential for Nosocomial Infection

• Age: the very young are affected by immature immune systems and immune systems decline as one ages.
• Heredity has genetic factors that impact on resistance to disease
• Nutrition intake through weight is a result of illnesses
• Stress may increase potential for infections through its levels of cortisone, which results in constant tension.
• Personal habits: smoking, excessive use of drugs/alcohol/ dangerous sexual practices
• History of one's health: history of diseases/lack of proper immunizations.
• Inadequate defence: broken skin, burns or trauma/ a medical regimen that causes a suppressed immunity.

Blood-borne Pathogens & Hepatitis

• The two found in the hospital are:

  • Hepatitis B virus (HBV)
  • Human immunodeficiency virus (HIV)

• Others: Hepatitis C, hepatitis D, and syphilis

• HBV attacks the liver causing:

  • Swelling & soreness
  • Loss of function
  • Weakness, feeling ill, loss of appetite, abdominal pain, fever, headache, jaundice and patients may not have symptoms

HBV & Blood Tests

• Blood tests will show after two to six weeks from symptoms.
• 85% recover in six to eight weeks.
• Needles show that always exposed with what you are testing.
• Contaminated needles will lead to HIV
• The SX cause: Loss of weight, listlessness, glandular pain, swelling, muscle and joint pain, are all indicators.
• One must first be exposed to the disease, it may however, take over 10 years to recognize the affects.

Forms of Hepatitis

• Hepatitis A is epidemic and found via, food, drink with bad sanitation. Incubation is 15-40 days and one will get jaundice after a week.
• Hepatitis B is a result of blood/product with hypodermic needles. (BT = sexually transmitted infections.) Often found in intravenous users. Hepatitis C is cause and transmitted via blood after using needles used by intravenous users.Hepatitis D (Delta) is caused by a virus and hepatitis B can only occur after a Hepatitis B Infection. Hepatitis E also found in areas of poor sanitation such as India and is often epidemic.

Microbial Control & Defenses

• Defenses include constitutive defenses such as mechanical and chemical actions, and even cellular defenses.
• Mechanical defenses come from shedding of cells from scrubbing or intact skin.
• Chemical defenses come from sweat glands secreting moistures/fatty acids, skin killing organisms, mucus, and acidity of the stomach, and even the vagina to counter microbes.
• Other types of flora would be the normal flora, therapeutic chemotherapy, and even immunization.
• Defenses come from being immunized, like giving infants pustules. Louis Pasteur developed vaccines such as anthrax/rabies. Vaccines are attenuated or killed, and are used for preventing or improving against disease.

Environmental Control

• Environmental control and Asepsis is when they are freely living with no infection, can be surgical or medical with a reduction of sterile procedure
• Temperature is key: most organisms want to lie at 37 degrees Celsius. Increase is prevented while a decrease could be good.

Chemical and Physical Method

• Chemical consists of disinfectant and antiseptics that help alter the environment found. The action can be Bacteriostatic: stopping bacteria to grow, or Bactericidal: which can lead to cellular actions and killings.
• Common solutions used for chlorine and iodium for invasive operations. Lastly and not least is hydrogen peroxide is used in deep wound incidents.

Chemical Physical method

• Consists of heat as rapidly killing due to being effective in dry settings. Also key is use of UV lights controlling airborne incidents however it cannot penetrate glass or body fluids which allows easy control

Hand Washing and Precautions

• Dr. Semmelweis of Vienna, who created techniques in using hand washing and created low volumes of vacation and autopsies cases after testing it.

Transmissions & Safety Precautions

• Hand washing is a must before and after any patients.
• When handling, be sure to always use gloves. It is in accordance to the personal safety equipment.
• Never have a needle recap. Over 800,000 needle related injuries have occurred. If not: use a one-handed scoop.
• In blood situations you must contain the spill. Use paper towels. Place the spill in some sort of container such as a bin.

Droplet & Airborne Precautions

• Always base the precaution on the transmission that the patient has.
• Airborne conditions include: TB, Varicella, and Rubella. Make the setting a negative pressure and keep the door closed at all instances for protection
• Droplets can have: influenza, adenovirus, mumps and rubella. It is through sneezing. The room should be kept with door open, to a reasonable feet. A drop feet is 3 before falling.

Contact Precaution

• These are: Aureus, Impetigo, Zoster, Varicella, and Hepatitis A. A dedicated room is needed. Be sure to have gloves on and always remove clothes after.