1. Microbiology Lesson 1: Introduction to Microbiology45
Microbiology
Lesson 1:
Introduction to Microbiology

2. 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.

3. 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.

4. 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

5. 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

6. 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)

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

8. 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

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

10. 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.

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

12. 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

13. 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

14. 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

15. 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)

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

17. 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

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

19. 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

20. 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)

21. 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

22. Carbuncles Caused by Staphylococci

23. 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

24. 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

25. Streptococci

26. 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

27. 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

28. 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

29. Bacillus/Bacilli

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

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

32. 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

33. 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

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

35. 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

36. Vibrio/Vibrios

37. 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

38. Spirillum/Spirilla

39. 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

40. 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

41. 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

42. 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

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

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

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

46. Protozoa

47. 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

48. Fungi

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

50. Parasites

51. Questions? 51