Microbiology Lesson 1: Introduction to Microbiology 45 Microbiology Lesson 1: Introduction to Microbiology

Lesson Objectives Upon completion of this lesson, students should be able to … Define and spell the terms to learn for this chapter. Define microbiology and its importance in patient care. Explain how microorganisms are classified.

Lesson Objectives Explain the differences among bacteria, viruses, protozoa, fungi, and parasites. Identify three different shapes of bacteria and a disease caused by each. Identify a disease caused by each of the five categories of pathogens.

Microorganisms: A Definition Also called microbes Living organisms that can only be seen with a microscope Harmless microorganisms can be found on the skin, in the digestive tract, and in the respiratory tract Microorganisms include protozoa, viruses, fungi, and bacteria

Pathogens Harmful microorganisms E. Coli is a common example of a pathogen Basic types of pathogens are listed below Fungi Rickettsia Parasitic Worms Virus Bacteria Protozoa

How Microorganisms Grow What is needed for a microorganism to grow? A few simple things: Food Moisture (e.g. mucous membranes) Darkness Appropriate temperature Aerobic versus anaerobic bacteria (those which need oxygen versus those that don’t)

Microbiology and Microorganisms Study of living organisms that cannot be seen with the naked eye Microorganisms: The living organisms which microbiology studies

Role of the Medical Assistant in Microbiology The assistant’s role may include: Proper use of PPE Monitoring equipment for repairs Performing quality control checks on equipment Proper collection and testing of specimens Educating patients Maintaining patient confidentiality

Classification of Microorganisms Many types Divided into: Pathogens Nonpathogens 98% to 99% are nonpathogenic

Naming Microorganisms Binomial system Genus and species Two names First name: Genus Always capitalized Second name: Species Always lowercase Being familiar with the system of nomenclature is important.

Classification and Structural Characteristics Classified by differences in structure: Presence or absence of organelles Eukaryotic cells Prokaryotic sells Subcellular microorganisms

Retention of Dyes Bacteria are characterized by how they react to stain or dye Gram stain used for most Gram-positive bacteria Gram-negative bacteria Acid-fast stain used for others

Classification and Oxygen Bacteria can also be categorized by their ability to survive in an oxygen-rich environment: Aerobes survive Anaerobes die Facultative anaerobes can live with some oxygen

Hemolytic Properties Bacteria are also categorized by their ability to hemolyze (burst) red blood cells in blood agar Microbiologist observes the characteristics for a colony of cells The organism that causes strep throat is beta hemolytic

Other Characteristics If they are capable of movement, their means of motility is unique to specific categories of microorganisms They may possess flagella (long whip-like extensions of the cytoplasm) or cilia (fine hair-like extensions)

Diseases Resulting from Pathogenic Microorganisms Strep throat, scarlet fever Diptheria Tuberculosis Influenza Pneumonia Meningitis Poliomyelitis Rabies

Diseases Resulting from Pathogenic Microorganisms (cont’d) Genital herpes Vaginitis Urinary tract infection Boils, carbuncles Chickenpox Scabies Lice Hepatitis A, B, and C Food poisoning

Diseases Resulting from Pathogenic Microorganisms (cont’d) E. coli diarrhea Septicemia Endocarditis Malaria HIV/AIDS Infectious mononucleosis Lyme disease Necrotizing fasciitis

Types of Microorganisms Bacterium/Bacteria Coccus/Cocci: Staphylococci Streptococci Diplococci Bacillus/Bacilli Tetanus E-Coli Spirillum/spirilla Syphilis Special categories of bacteria Microbacteria Rickettsia Mycoplasma Chlamydia

Bacterium/Bacteria Small, unicellular microorganisms that are capable of rapid reproduction Reproductive ability explains how some infections become overwhelming in a short period of time and can be dangerous Bacteria may be named for their morphology (shape): Cocci (spherical) Bacilli (rod-shaped) Spirilla (spiral shape)

Cocci Round bacteria that are arranged in various configurations. Staphylococci are gram-positive, grape-like clusters of cocci some of which are pathogenic Nonpathogenic staphylococci are found on our skin and in many of our body orifices, or openings

Carbuncles Caused by Staphylococci

Staphylococcus aureus (S.Aureus) Staph The major pathogen of this genus and may be found as normal flora in the nose and on the skin Causes infection especially when resistance is lowered by a break in the skin or in the mucous membranes A common cause of nosocomial infections and may also cause pneumonia, meningitis, and septicemia in individuals with reduced resistance

Methicillin-Resistant Staphylococcus Aureus (MRSA) Form of S. Aureus Produces an enzyme that makes the organism resistant to penicillins and cephalosporins normally used for treatment and renders these antibiotics ineffective Tests are available to indicate the presence or absence of this enzyme and help determine the most favorable treatment

Streptococci

Streptococci Round, gram-positive bacteria arranged in chains Some are nonpathogenic, others are dangerous to humans Part of the normal flora of the upper respiratory tract and skin

Group A beta-hemolytic Streptococcus pyogenes Causes a variety of diseases varying from mild such as strep throat to life threatening Examples include: Strep throat Pneumonia Tonsillitis Scarlet fever Rheumatic fever Acute glomerulonephritis Bacterial endocarditis Necrotizing fasciitis

Diplococci Occur in pairs Some are gram positive others are gram negative Examples of diseases include: Gonorrhea, a sexually transmitted infection Bacterial meningitis Septicemia Meningococcal meningitis

Bacillus/Bacilli

Bacillus/Bacilli Rod-shaped bacilli may be pathogenic or nonpathogenic Some bacilli are gram positive and others are gram negative

Bacillus/Bacilli Responsible for a wide variety of illnesses including: Gastroenteritis UTIs Whooping cough Tetanus Botulism Tuberculosis Pneumonia

Gram-Negative Bacilli Enterobacteriaceae are a large family of gram-negative bacilli found mainly in the intestinal tract Many of them will cause infections in other body locations One type, Escherichia coli, is most frequently associated with UTIs The group of Salmonella organisms is a major cause of foodborne illnesses worldwide

Helicobacter Pylori Another gram-negative bacillus Discovered in the early 1980s Organism is found in about half of the population and causes no symptoms in most individuals H. Pylori is the causative agent of peptic ulcers and a risk factor in gastric malignancy in some infected persons

Helicobacter Pylori Organism is responsive to a number of antibiotics including tetracycline The discovery of H. Pylori led to major breakthroughs in ulcer treatment

Gram-Positive Bacilli May be found in chains or singly, and are spore forming or nonspore forming Notable in this group are: Clostridium botulinum, which causes botulism Clostridium tetani, which causes tetanus

Vibrio/Vibrios

Vibrio/Vibrios Comma-shaped bacilli Main pathogen is Vibrio cholerae whose enterotoxin causes cholera Cholera is: Characterized by profuse watery stools, vomiting, leg cramps, dehydration, and shock Caused by ingesting drinking water or eating shellfish from water contaminated with infected urine, feces, or vomitus Common in Asiatic countries, and travelers to these areas can be vaccinated for protection

Spirillum/Spirilla

Spirilla or Spirochetes Spiral-shaped or corkscrew-shaped organisms Rods that are twisted in various shapes Classified as a separate category of bacteria Some are nonpathogenic and are found in certain areas of the body and others, such as Treponema pallidum, cause the sexually transmitted infection syphilis

Spirilla or Spirochetes Borrelia burgdorferi was discovered in the mid-1970s to be the causative agent of Lyme disease Lyme disease is a deer tick-borne disease

Mycobacteria A type of bacteria Have a different type of material in the cell wall and can only be stained with an acid-fast stain Mycobacterium tuberculosis is the causative agent of tuberculosis and Mycobacterium leprae, is the cause of leprosy These organisms do not stain well with a Gram stain In a positive slide for acid-fast Bacilli (AFB), the slender Bacilli will appear pink with an acid-fast stain

Rickettsia and Chlamydia Bacterial parasites that live in ticks and mites and transmit the disease when they bite humans Diseases: Rocky Mountain spotted fever and typhus Chlamydia An obligate parasite, but it does not live in arthropod hosts Must invade living cells to reproduce. Disease: Chlamydia trachomatis is an STI

Types of Microorganisms Viruses Smallest known infectious organisms Require an electron microscope to visualize Parasitic Depend on living cells of other organisms for growth

Diseases Caused by Viruses Colds Chickenpox Mumps Infectious mononucleosis Warts Hepatitis Measles Encephalitis Herpes

Types of Microorganisms Protozoa One-celled organism Parasitic and nonparasitic Move with cilia or false feet Examples: Amebic dysentery Malaria

Protozoa

Types of Microorganisms Fungus/fungi Parasitic and some nonparasitic plants and molds Depend on other life forms for nutrition Include yeasts Reproduce by budding Resistant to antibiotics Examples: Athlete’s foot Yeast infection

Fungi

Types of Microorganisms Parasites Worms Flatworms Tapeworms Roundworms Pinworms Insects Deer tick (Lyme disease) Scabies Lice

Parasites

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