Chapter 4 Microbiology

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Microbiology

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The study of microorganisms.

  • The scientific study of nature, life and action of microorganisms.

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Contamination

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The state of being soiled by contact with infectious organisms or other material.

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33 Terms

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Microbiology

The study of microorganisms.

  • The scientific study of nature, life and action of microorganisms.

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Contamination

The state of being soiled by contact with infectious organisms or other material.

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Sterile Processing technicians must have a basic understanding of microbiology for 2 reasons:

  • They have a responsibility to protect patients from microorganisms in the healthcare environment.

  • The nature of their job duties places them and their co-workers in harm’s way for exposure to harmful microorganisms.

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Microorganism facts

  • Cells are the basic units of all living organisms (plants, animals, protozoa and bacteria)

  • Cells are the smallest unit that can live, grow and reproduce

  • Cells differ in size and shape, but they all have:

    • A nucleus

    • Cytoplasm

    • A cell membrane

  • Bacterial cells differ from both plant and animal cells because they have no membrane to separate the nucleus from the cytoplasm

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Protozoa

Microscopic, single-celled organisms with a membrane-bound nucleus that are found in most habitats worldwide.

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What percentage is beneficial to our lives?

95%

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Bad Microorganisms

  • Harmful microorganisms can cause infections when introduced into a body site where they are not normally found

  • Pathogens are a specific concern for CS professionals, as disease-causing organisms can reside on instruments and devices used in patient care, leading to healthcare-associated infections (HAI’s)

    • An estimated 1.7 million patients per year acquire an HAI and 98,000 of them (1 in 17) will die from it

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Pathogen

Capable of causing disease (disease-causing microorganism)

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Classification of Microorganisms

  • The 1st word in a microorganism’s name (always capitalized) is the genus(family) of the microorganism

  • The 2nd word is the specific name (species) of the organism

  • Microorganisms are identified and classified according to certain characteristics

    • Bacteria

    • Non-Bacteria

      • Viruses

      • Protozoa

      • Fungi

      • Prions

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Characteristics of Bacteria

  • Bacteria are incredibly small and can only be seen with a microscope that can magnify at least 900 times.

  • Bacteria are measured by Microns and most of 1-2 microns in size

  • The most common ways to identify and classify bacteria are by:

    • Shape

    • Color change

    • Need for oxygen

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Micron

1/25,000 of an inch or 1/1,000 of a millimeter

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Need for oxygen: Aerobic

Requiring the presence of air or free oxygen

  • These bacteria require oxygen

  • May grow in liquids if the liquid has oxygen dissolved in it

  • Example’s

    • Clostridium

    • Staphylococcus

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Need for oxygen: Anaerobic

Can live in the absence of atmospheric oxygen

  • These bacteria do NOT require oxygen

  • Cannot grow in an environment where oxygen is present

  • Example’s

    • C. Tetanus

    • C. Botulinum

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Shapes of bacteria

  • Spherical

    • These bacteria are shaped like a circle or a sphere (coccus)

    • Examples: Staphylococcus aureus and Streptococci

  • Rod

    • These bacteria are shaped like rods or bricks (bacillus)

    • Examples: Pseudonomas aeruginosa and Enterobacteria

  • Spiral

    • These bacteria are shaped like spirals (spirilla)

    • Example: Helicobacter pylori

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Endospores

  • Some bacteria can change into a different form called enodospores (spores) by developing a thick coat around the cell’s nucleus when conditions required for growth are not adequate

  • Spores can become infectious and produce toxins once inside the body

    • Bacillus anthracis causes anthrax(an infection)

    • The Clostridium species causes tetanus(lockjaw) and botulism (primary affects the nervous system; leading to muscle paralysis)

  • Spores are very resistant to disinfection and other conditions such as heat, making them very difficult to kill

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Endospores(Spores)

Microorganisms capable of forming a thick wall around themselves enabling them to survive in adverse conditions; a resistant form of bacterium.

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Color Change in Bacteria

Gram Positive +

  • These bacteria have no outer membrane and will retain the purple stain after treatment with iodine

    • Stains Purple

  • Examples:

    • Staphlyococcus aureus

    • Bacillus anthracis

    • Clostridium difficle (C.diff)

Gram Negative -

  • These bacteria have an outer membrane and will Not retain the purple stain after treatment with iodine

    • Stains Pink

  • Examples:

    • Pseudonomas aeruginosa

    • Escherichia coli (E.coli)

    • Klebsiella

Acid Fast (Ziehl-Neilson stain)

  • Acid fast bacteria are difficult to stain and may require heat or other agents to become stained

    • Once stained, the bacteria will resist color change

  • Examples:

    • M. Tuberculosis

    • M. Leprae

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Conditions for bacteria growth

The suitable environments for bacteria can be broken down into:

  • Nutritional needs

  • Temperature

  • Moisture/humidity

  • pH

  • Light

Pathogenic bacteria are moat likely to thrive where their specific nutritional needs can be met

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pH

Measure of alkalinity or acidity on a scale of 0 to 14

  • pH of 7 is neutral (neither acid nor alkaline)

  • pH above 7 is alkaline

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Temperature requirements for bacteria

Bacteria pathogenic to humans prefer the moderate temperature range and are called Mesophiles.

  • Optimal temperature for growth

    • Cold temp: 59F to 68F

    • Moderate temp: 68F to 113F

    • Warm temp: 122F to 158F

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Conditions of bacteria growth

  • Dark conditions are favorable to the growth of bacteria

  • Sunlight is lethal to organisms while they are actively growing

  • The most lethal light is ultraviolet (UV) light

  • Bacteria are transmitted primarily by:

    • Droplets

    • Contaminated water or food

    • Direct contact

    • Through wounds

    • Through the air

    • By disease-carrying animals

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Vegetative stage

States of active growth of microorganisms (as opposed to resting or spore stages)

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How bacteria grow

  • When optimal conditions are present, most bacteria and other microorganisms reproduce approximately every 20 minutes

  • Microorganisms reproduce in a process called binary fission through which the “mother” cells divides into 2 “daughter” cells

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Binary Fission

The typical method of bacterial reproduction in which a cell divides into 2 equal parts

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Multiple-Drug resistant organisms

  • Microorganisms can adapt and change as a means of survival

  • Multiple-Drug resistant organisms (MDRO) have become resistant to antibiotics used to treat bacteria infections and are increasingly found in healthcare facilities

  • Resistant pathogens can produce many types of infection in any body site

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Common drug resistant bacteria: Methicillin-resistant Staphylococcus aureus (MRSA)

  • Lives on the skin and is known for causing severe infections

  • Spread by:

    • Direct contact with someone with the infection

    • Touching a contaminated surface

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Common drug resistant bacteria: Vancomycin-resistant Enterococci (VRE)

  • Lives in the bowels

  • Transmitted when:

    • Hands become contaminated from feces, urine or blood that is infected

    • Touching a contaminated surface

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Common drug resistant bacteria: Vancomycin-resistant Strephtococcus pneumonia

  • Lives asymptotically in the nose and pharynx of healthy carriers

  • Causes pneumonia

  • Spread by:

    • Direct contact with infected droplets from coughing or sneezing

    • Contact with other infected fluids

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Common drug resistant bacteria: Klebisiella

  • Found on the hands and in the intestinal tract

  • Causes pneumonia, nasal infections, urinary tract, wound and bloodstream infections

  • Transferred from infected patients or surfaces through hand contact

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Common drug resistant bacteria: Acinetobacter

  • Found normally in soil

  • Causes various illnesses ranging from pneumonia to serious blood or wound infections

  • Transmitted by person-to-person contact or by contact with contaminated surface

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Common drug resistant bacteria: Carbapenum-resistant Enterobacteriaceae

  • A normal part of the human gut bacteria, including E. Coli

  • Infections associated with the use of devices such as endoscopes, ventilators, urinary or IV catheters

  • CRE infections are very difficult to treat and can contribute to death in up to 50% of patients who become infected

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Common drug resistant bacteria: Pseudonomas aeruginosa

  • Frequently found in water and soil

  • Causes urinary tract, respiratory system, gastrointestinal, soft tissue and joint infections

  • These infections occur particularly in immunocompromised patients (severe burns, cancer, AIDS)

  • Transmitted through hand to hand contact or contact with contaminated surfaces

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