Medical Microbiology: Medical School Crash Course

Medical Microbiology Medical School Crash Course™

"To download the audio version of this course, please visit our website"

www.AudioLearn.com

Table of Contents Preface............................................................................................................................................ 8 Chapter 1: Laboratory Diagnosis of Diseases ............................................................................ 1 Microscopy ................................................................................................................................. 1 Optical Microscopy..................................................................................................................... 1 Electron Microscopy ................................................................................................................... 5 Ultraviolet Microscopy ............................................................................................................... 6 Infrared Microscopy.................................................................................................................... 6 Digital Holographic Microscopy ................................................................................................ 7 Laser Microscopy........................................................................................................................ 7 Microbiological Cultures ............................................................................................................ 7 Bacterial Cultures........................................................................................................................ 8 Viral cultures............................................................................................................................... 8 Eukaryotic Cell Cultures ............................................................................................................. 8 Serology ...................................................................................................................................... 9 Key Takeaways ........................................................................................................................... 9 Quiz ............................................................................................................................................. 9 Chapter 2: Human Immune System ......................................................................................... 13 Innate Immune System ............................................................................................................. 13 The Barrier Effect ..................................................................................................................... 13 The Inflammatory Response ..................................................................................................... 15 The Role of the Complement System ....................................................................................... 16 Cells of the Innate Immune System .......................................................................................... 16 Other Aspects of the Innate Immune System ........................................................................... 17 Adaptive Immune System ......................................................................................................... 18 Cells of the Adaptive Immune System ..................................................................................... 19 Antigens and their Presentation ................................................................................................ 19 T Lymphocyte Activity ............................................................................................................. 20 B Lymphocyte Activity............................................................................................................. 21 Vaccines .................................................................................................................................... 22 Key Takeaways ......................................................................................................................... 22 Quiz ........................................................................................................................................... 23 Chapter 3: Basic Bacteriology ................................................................................................... 26 Bacteria Basics .......................................................................................................................... 26

Bacterial Morphology ............................................................................................................... 26 Internal Bacterial Structure ....................................................................................................... 28 Extracellular Structures............................................................................................................. 29 Endospores ................................................................................................................................ 30 Bacterial Metabolism ................................................................................................................ 30 Bacterial Reproduction ............................................................................................................. 31 Bacterial Genomes and Genetics .............................................................................................. 32 Bacteriophages .......................................................................................................................... 33 Behavior of Bacteria ................................................................................................................. 33 Bacterial Interactions with other Organisms............................................................................. 34 Key Takeaways ......................................................................................................................... 35 Quiz ........................................................................................................................................... 35 Chapter 4: Bacterial Diseases in Humans ................................................................................ 38 Pathogenic Bacteria .................................................................................................................. 38 List of Common Human Infectious Diseases ........................................................................... 39 Mechanisms of Pathogenesis .................................................................................................... 39 Anaerobic Infections ................................................................................................................. 40 Anaerobic CNS Infections ........................................................................................................ 41 Upper Respiratory Tract Anaerobic Infections ......................................................................... 41 Anaerobic Lung Infections ....................................................................................................... 42 Anaerobic Abdominal Infections .............................................................................................. 42 Anaerobic Infections of the Female Genital Tract.................................................................... 43 Anaerobic Infections of the Skin and Connective Tissue ......................................................... 43 Anaerobic Infections of the Bones and Joints........................................................................... 44 Anaerobic Blood Infections ...................................................................................................... 45 Anaerobic Infections of the Newborn ....................................................................................... 45 Bacteremia ................................................................................................................................ 45 Bacterial Pneumonia ................................................................................................................. 46 Key Takeaways ......................................................................................................................... 47 Quiz ........................................................................................................................................... 47 Chapter 5: Basic Virology .......................................................................................................... 51 Virus Basics .............................................................................................................................. 51 Viral Origins ............................................................................................................................. 52 Properties of Viruses ................................................................................................................. 54

Virus Morphology Types .......................................................................................................... 54 The Viral Genome..................................................................................................................... 55 The Viral Replication Cycle ..................................................................................................... 56 Viral Replication Process .......................................................................................................... 57 Classifying Viruses ................................................................................................................... 59 The Epidemiology of Viruses ................................................................................................... 59 Viruses and Cancer ................................................................................................................... 60 The Immune System and Virus Infection Treatment................................................................ 60 Viruses and the Treatment of Diseases ..................................................................................... 61 Key Takeaways ......................................................................................................................... 61 Quiz ........................................................................................................................................... 61 Chapter 6: Viral Diseases in Humans ....................................................................................... 65 Viral Disease Basics ................................................................................................................. 65 Clinically-significant Viral Infections in Humans .................................................................... 66 Key Takeaways ......................................................................................................................... 70 Quiz ........................................................................................................................................... 70 Chapter 7: Fungal Diseases in Humans .................................................................................... 73 Fungi Basics .............................................................................................................................. 73 Pathogenic Fungi ...................................................................................................................... 74 Candida Infections .................................................................................................................... 74 Aspergillus Infections in Humans............................................................................................. 75 Cryptococcus Infections............................................................................................................ 76 Histoplasma Infections.............................................................................................................. 77 Pneumocystis Infections ........................................................................................................... 78 Key Takeaways ......................................................................................................................... 78 Quiz ........................................................................................................................................... 79 Chapter 8: Protozoal Diseases in Humans................................................................................ 82 Protozoa Basics ......................................................................................................................... 82 Protozoan Infection..................................................................................................................... 82 Giardia Infections...................................................................................................................... 83 Cryptosporidium Infection ........................................................................................................ 84 Amoebiasis (Amoeba Infection) ............................................................................................... 85 Cyclospora Infections ............................................................................................................... 86 Toxoplasmosis .......................................................................................................................... 86

Plasmodium Infections.............................................................................................................. 87 Key Takeaways ......................................................................................................................... 89 Quiz ........................................................................................................................................... 89 Chapter 9: Parasitic Diseases in Humans ................................................................................. 93 Parasitic Disease Basics ............................................................................................................ 93 Helminthiasis ............................................................................................................................ 93 Ascaris Infections...................................................................................................................... 95 Filariasis .................................................................................................................................... 96 Cestodiasis ................................................................................................................................ 96 Trematodiasis ............................................................................................................................ 97 Diagnosis and Treatment of Helminthiasis ............................................................................... 98 Scabies Infection ....................................................................................................................... 98 Pubic Louse............................................................................................................................... 99 Pediculosis Capitis .................................................................................................................. 100 Pediculosis Corporis ............................................................................................................... 101 Bed Bug Infestation ................................................................................................................ 101 Key Takeaways ....................................................................................................................... 101 Quiz ......................................................................................................................................... 101 Chapter 10: Antibacterial Medications .................................................................................. 105 Antibiotic Basics ..................................................................................................................... 105 Antibiotic Sources................................................................................................................... 105 Using Antibiotics in Medicine ................................................................................................ 106 Classes of Antibiotics ............................................................................................................. 107 Antibiotic Resistance .............................................................................................................. 111 Key Takeaways ....................................................................................................................... 111 Quiz ......................................................................................................................................... 111 Chapter 11: Antiviral Medications.......................................................................................... 115 Antiviral Drug Basics ............................................................................................................. 115 Vaccinations............................................................................................................................ 116 Antiviral Drug Targets ............................................................................................................ 116 Key Takeaways ....................................................................................................................... 119 Quiz ......................................................................................................................................... 119 Chapter 12: Antifungal, Antiprotozoal, and Antiparasitic Medications ............................. 123 Antifungal Drugs .................................................................................................................... 123

Antifungal Classes .................................................................................................................. 123 Antiprotozoal Drugs................................................................................................................ 124 Antiparasitic Drugs ................................................................................................................. 125 Key Takeaways ....................................................................................................................... 125 Quiz ......................................................................................................................................... 126 Summary .................................................................................................................................... 130 Course Questions and Answers ............................................................................................... 132

Preface The purpose of this brief course is to give the student of microbiology a review of medical microbiology. This discussion will cover aspects of the microbial world most associated with human disease.

The first chapter of the course will outline how microbial organisms and their diseases are best studied. The basics of the different methods of microscopy will be covered in this chapter, as well as the use of cultures when diagnosing infectious diseases. The use of serology will also be discussed.

The second chapter of the course will involve an overview of the human immune system and vaccines. Almost all infectious diseases are eliminated by the immune system. People with compromised immune systems are prone to recurrent infections, especially opportunistic infections.

Basic bacteriology will be discussed in the third chapter of this course. Bacteria are unique, prokaryotic organisms, which may cause several varying diseases in humans. Bacterial metabolic processes will also be covered, as this is crucial to understanding how they cause disease.

In the fourth chapter of the course various bacterial diseases that affect the human host will be discussed. There are vast amounts of bacteria in nature, but only a few cause serious disease in humans. Those which commonly cause human diseases will be discussed in this chapter.

The fifth chapter of this course will cover the topic of virology, or the study of viruses and their behavior. Viruses are very simple life forms that infect humans and other organisms. There are viruses that infect human hosts and other that only infect plants, animals, and bacteria.

The sixth chapter of the course discusses common viral diseases that afflict humans. These range from mild diseases, such as the common cold, to more severe and life-threatening diseases, such as HIV and hepatitis C. We will discuss human fungal diseases in the seventh chapter of this course. Fungal diseases range from minor diseases to more severe diseases requiring aggressive therapy. Fungal organisms are not much different biochemically from human cells and thus more difficult to kill without significant side effects.

The eighth chapter of this course will cover protozoal diseases. Protozoa are unicellular, eukaryotic, and non-photosynthetic organisms, with few actually causing human disease. Many protozoal infections are enteric in nature, and cause similar symptoms from organism to organism. The importance of understanding these diseases as it relates to the health of most people in the world will be emphasized.

The ninth chapter of this course will discuss human-host parasitic diseases. While protozoa are considered parasitic, this chapter will cover other parasitic diseases, including those caused by endoparasites (which cause internal disease) and those caused by ectoparasites (which cause external human disease).

We will discuss antibacterial medications, known as antibiotics, in the tenth chapter of this course. There are dozens of antibiotics that vary according to their mechanism of action on different bacterial organisms. Some antibiotics are bactericidal and kill bacteria outright.

Others are bacteriostatic, meaning they hinder the growth of bacteria, and require an intact immune system to fully eradicate bacterial infections.

In the eleventh chapter of the course, we will discuss antiviral drugs. Drugs that act against viruses mainly attack an element of the life cycle of viruses, while there are a select few that act by enhancing the immune system’s response against the viral organism.

The twelfth chapter of the course is a short discussion of other antimicrobial agents used for the treating fungal, protozoal, helminthic, and parasitic infections. These represent a wide range of organisms—each requiring a specific antimicrobial agent to effectively treat the infection or infestation.

After completing this course, you will have an understanding of several infective organisms and how they interact with humans on a microscopic level. You will also better understand medical microbiology and the varying associated pathogens and diseases, with their treatments.

Chapter 1: Laboratory Diagnosis of Diseases While this course will mainly discuss human medical microbiology, including the pathogens seen in common microbiologically-based diseases, a discussion of medical microbiology is not complete without first discussing the tools and techniques used in detecting these diseases.

This chapter will focus on the techniques of microscopy, the culturing of microorganisms, and serology, which is one way many microbiological diseases are diagnosed in clinical settings.

Microscopy Microscopy involves using different types of microscopes to view extremely small objects that cannot be seen with the naked eye. There are three types of microscopy that will be discussed in this chapter: optical microscopy, electron microscopy, and scanning probe microscopy—the latter two tending to be more specialized in nature.

Both optical and electron microscopy involve the reflection, refraction, or diffraction of electromagnetic radiation/electron beams that interact with a fixed specimen. The reflection, refraction, or diffraction is then and processed into a specimen image. All types of microscopy are central to the evaluation of microbiologically-caused diseases, and research of these diseases.

Optical Microscopy Optical microscopy is also referred to as light microscopy because it involves the passage of light either through the sample or reflected upon the sample using one or more lenses to obtain a magnified image of the sample. The produced image can be seen by the eyes, photographed, or captured in a digital medium. While basic light microscope involves the use of a single lens, a stage, and basic attachments, light microscopes can be extremely complex and utilize multiple lenses. One of the more advanced light microscopes involves capturing digital images of the sample with a CCD camera rather than actually visualizing the sample.

The main limitations of optical microscopy include three things: It can only image things that strongly refract light or are dark in color, the resolution is only about 0.2 micrometers or about 1500X power, and focusing the image may be difficult when points of light are seen outside the focal plane.

Unfortunately, live cells are not dark enough and have no ability to provide contrast as their inner structures lack in color. The best way to see items using light microscopy is to have the organism killed and then stained with dyes that provide contrast of the different organelles under the microscope. Selective dyes are used for at least two-color staining. The major downside of staining is that the organism must be killed. Artifacts can be created from the staining process that are not part of the organism. However, staining can help identify certain parts of the structure and will increase the contrast in the sample. Different optical techniques may also assist with identifying certain structures, including bright field illumination that helps send light through the sample, cross-polarize light illumination, which uses polarized light, dark field illumination techniques, and phase contrast illumination.

1

Figure 1 shows a slide illuminated by light microscopy:

Figure 1 With bright field microscopy, white light is shined through the sample, illuminating it from below so it can be observed through the lens from above. The main limitation of this technique is that samples must be very thin, and blurring of the sample may occur when some parts are out of focus. The main advantage is this is a very simple technique involving a simple light microscope. Sample preparation is also minimal with this technique.

With an oblique illumination technique, a three-dimensional image can appear using the microscope, which can highlight features not observed with bright field microscopy. However, like bright field microscopy, it requires a thin sample and there will be blurry objects that decrease the resolution of the image.

With dark field microscopy, there is improvement of the contrast of specimens that don’t need to be stained to be seen. It relies on a carefully applied light source to decrease the amount of un-scattered light in the microscope, which increases the contrast of the image. It is great for transparent objects and doesn’t require much sample preparation. The main disadvantage of dark field microscopy is that it uses low lighting techniques that can affect the ability to see the image.

2

Figure 2 demonstrates bacteria as seen using dark field microscopy:

Figure 2 There is a special technique known as Rheinberg illumination, which is a type of dark field microscopy that involves using colored filters. These filters are placed under the condenser and causes light rays to become slightly colored as they pass through the object. It can enhance the contrast of certain-colored objects or samples.

Dispersion staining is a microscopy technique that results in getting a colored image of an object that is normally without color. This requires no particular dyes or stains, and involves using different light sources that cause coloration of the object.

Phase contrast microscopy will show proportional differences in the optical density of the object. It uses differences in the refractive index of an object to show contrast under the microscope. It has been used since the 1930s, and is helpful because it shows up a darklycolored nucleus against a lighter-colored cytoplasm. It can’t be used with thick objects and even small objects will have a halo that may obscure the detail the researcher is looking for.

The image is created by differences in the way light is diffracted between the aspects of the sample. The halo problem (obscuring the image) is the biggest disadvantage of this technique.

Interference contrast microscopy is more expensive, but is something that will give a superior image when compared with other techniques. The nucleus will show up in a cell in three 3

dimensions because of the way light is applied to it. There is a better depth of field and special staining is not needed. It relies on the use of special prisms that will improve the visibility of the image. Any time there is a non-homogeneous specimen, the light will travel in different ways to highlight the different features of the object/specimen. This technique requires a polarized light source with at least two polarizing filters necessary (one below the condenser and one above the objective).

Interference reflection microscopy is another microscopy technique. It is also called “RIC” or reflected interference contrast that needs the adhesion of the specimen onto the slide, which causes an interference signal. The interference relies primarily on the adherence factor. Light is reflected off the object or specimen rather than transmitted through it.

Sometimes fluorescence microscopy is necessary. This uses specimens that automatically fluoresce under certain circumstances or fluorescent stains and dyes that impart a fluorescent quality to certain parts of the cell. Things that don’t need a stain are said to have autofluorescence. Stains used include fluorescein dye and rhodamine dye. They can bind to antibodies and can be used when evaluating for dyes that bind to certain parts of the cell, causing them to fluoresce. Antibodies can be made in rabbits and then bound to a fluorescent dye component, creating a complex that will bind to certain parts of the cell.

Figure 3 depicts a slide illuminated using fluorescence microscopy:

Figure 3 Fluorescent proteins like the green fluorescent protein (GFP) have been used in microbiology and involves the linkage between a fluorescent compound and a target protein—making something that will fluoresce under the microscope. Certain organisms will express the protein 4

which will result in the in vivo study of the protein as it exists in the cell. Direct fluorescence microscopy has become very effective in allowing microbiologists to tag specific areas of the cell and view them clearly under the microscope as fluorescing objects.

Confocal microscopy is another technique that uses a pinhole and a light source. The pinhole focuses light on a specific area of the cell which facilitates higher resolution. This is a great technique to use when viewing three-dimensional structures of the object or specimen is important.

Using single plane illumination microscopy or light sheet fluorescence microscopy involves focusing light through a cylinder-shaped lens or by scanning a line of light in a plane perpendicular to the axis of the objective, allowing for high resolution of the specimen. It involves using several different prisms that will provide enhanced resolution and fluorescence of the specimen.

Wide-field multiphoton microscopy is an optical microscopy technique where a large aspect of the object is illuminated which produces images without scanning the specimen. It requires high intensities of light to produce an image, and uses a laser device to get a high-resolution image of the specimen. Wide fields can be identified under the microscope with the ability to view large portions of the specimen without scanning it little-by-little.

Electron Microscopy Electron microscopy does not use light, and can see things with a much higher resolution.

There are two types of electron microscopy, known as transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Both types have extremely high resolutions. In TEM, the outcome looks similar to light microscopy but the resolution is about 0.05 nanometers as opposed to light microscopy, which is much less sensitive. Scanning electron microscopy is a three-dimensional electron microscopy technique that looks at the surface of specimens. It has a resolution of about 0.4 nanometers.

Figure 4 shows neutrophils illuminated with electron micrroscopy:

5

Figure 4 Another technique is called atomic force microscopy or AFM, which is a type of scanning probe microscopy technique. There are other similar techniques—all of which require the physical contact with a probe to the surface of the object, which needs to be very flat in nature.

Ultrasonic force microscopy, or UFM, takes a good look at flat areas that don’t show up well using atomic force microscopy. This technique (and AFM) both improve the resolution of the image that can be achieved. The probe used in this technique is able to detect ultrasonic waves, giving much greater detail than the AFM technique alone. It applies ultrasonic vibratory waves to the sample, providing a great deal of resolution.

Ultraviolet Microscopy There are two main purposes of ultraviolet microscopy. The first is to be able to use the shorter wavelengths seen in ultraviolet electromagnetic waves to improve the image resolution to a greater degree than optical microscopy. This technique is used for the non-destructive inspection of non-living devices with extremely small features (like semiconductors). The second main use for this technique is contrast enhancement, where the response of individual specimens is enhanced in relationship to their surroundings because light and the molecules interact differently with UV light. Certain proteins that are completely transparent under optical microscopy technique can be easily seen under UV light because the crystals of the protein show up differently with UV light application.

Infrared Microscopy This uses microscopy under infrared wavelengths. In the typical microscope, such as the Fourier Transform Infrared Spectrometer (FTIR), there is a combination of an infrared detector and a light microscope. Chemical analysis can be done with infrared spectroscopy and the 6

analysis can be “seen” with the FTIR machine. This is called infrared microspectroscopy. It is used mainly for infrared chemical imaging, where the image contrast is determined by whatever infrared wavelengths are selected by the microscopist.

The resolution of an infrared microscope is somewhere between that of an electron microscope and an optical microscope, being able to pick up things with a resolution of about three to thirty micrometers. (Remember that the electron microscope can pick up things in the few nanometer range).

Digital Holographic Microscopy This is also called DHM and involves using a coherent, monochromatic light-source recorded on a specific type of sensor. The image is reconstructed digitally from a computer, providing a hologram of the object. A bright field and phase-shifted image is made from this. It can be a reflective technique or a transmissivity technique. When used reflectively, the image can provide a topographic map of the reflective surface of the specimen. Transmission technique will provide an image similar to optical transmission microscopy but with better resolution.

The big benefit of this technique is that the focus can be adjusted after recording the image as all focus planes can be recorded simultaneously by the device. This allows the “scanning” of the surface of the specimen very quickly. It uses low cost software and a computer to create a good holographic image of the object.

Laser Microscopy Laser microscopy is a relatively new technique that is rapidly being used by microscopists to evaluate biological specimens. This technique uses pulses of laser light using x-ray lasers that will be used to make extremely high resolution three-dimensional images of things (resolutions of about 0.3 nanometers). The specimen is naturally destroyed by the laser exposure but a good picture of the image can be obtained before the material degrades or explodes.

Microbiological Cultures Before getting a microscopic image of something, it must be cultured so enough of the organism or cell can be placed on a slide. There are different types of cultures that will grow bacteria, viruses, or eukaryotic cells. They are mainly used to grow enough of an organism or cell to properly identify them, especially when they are originally in amounts too small to be identified.

Microbial cultures are extremely important when studying medical microbiology and in looking for infectious diseases. Each culture is specifically obtained, such as a throat swab or a blood sample. After this, the swab or sample of blood is placed into a liquid medium or swabbed onto a solid medium. The organism is grown under optimal circumstances to ensure the organism grows.

Sometimes it is necessary to get a pure culture of a specific microorganism (particularly for research purposes). A pure culture is an identical population of cells or a group of growing multicellular organisms that don’t have an attached organ or body. Solid cultures often require 7

the use of an agar medium, while guar gum is a cheaper, solid medium. There are many types of liquid media that contain nutrients capable of helping the organism grow.

Bacterial Cultures Bacterial cultures can be solid or liquid and are perhaps the most common cultures used in medical microbiology. One technique involves growing bacteria in a liquid broth that grows a freely-growing bacterium species. One example is the Luria broth, which grows mainly bacteria. Liquid cultures are especially used when a large amount of bacteria are necessary to be grown overnight. Blood or other samples are inoculated into the liquid broth and grown in a shaker device.

Some bacterial cultures are done using Petri dishes and agar medium. Other solid media can be used but agar is the most common. Bacteria are inoculated onto the plate and grown at the optimal growing temperature of the bacterium, which usually the same as human body temperature (thirty-seven degrees Celsius). Environmental cultures are grown at lower temperatures but this would be rare in medical microbiology. They can be sampled and, after enough of the bacterium has been cultured, the plate is stored upside down in a refrigerated setting for a long period of time.

Agar isn’t often purely used but contains several types of additives which allow for the selective growth of some types of bacteria, with the exclusion of other types of bacteria. Antibiotics can be additives in the agar medium to allow only antibiotic-resistant organisms, growing a purer culture of antibiotic-resistant bacteria. Discs can be placed on the agar that contain antibiotics, which will cause a “halo-effect”, if the bacteria are sensitive to the antibiotic impregnated into the disc.

Stab cultures are similar to solid agar plate cultures but involve solid media in a test tube.

Bacteria are inoculated into the solid culture medium via an inoculation needle. This is especially good for the short-term growth and storage of bacteria.

Viral cultures It is more difficult to grow viruses or bacteriophages in culture. Bacteriophages are cultured by infecting bacterial cells and then by growing the bacterial cells in culture. The virus is then harvested from the infected bacteria after they are grown and lysed. The same thing can be done in those viruses that infect eukaryotic cells. In general, viral cultures cannot be done without a host cell that grows in culture.

Eukaryotic Cell Cultures These can be done for eukaryotic cells that are single-celled (like yeast organisms or other fungal organisms) or multicellular (as in tissue cultures of human cells). Individual cell types are isolated and then are grown in a liquid medium to make many more of the same cellular structures. The goal is to have a pure cell culture by isolating pure cells out of a group of cells.

8

Serology Serology involves using serum analysis to make a diagnosis in a microbiological setting, such as looking for antibodies in a person’s serum to a specific microorganism, which can be bacterial or viral in nature. Serology can also be used to look for antibodies in cases of transplantation or if a person gets the wrong blood transfusion. Autoimmune diseases can be diagnosed using serology and blood type analysis can be done with this technique.

There are several serology tests that can be done, including precipitation studies, complement fixation studies, ELISA testing, agglutination testing, chemiluminescence testing, and fluorescent antibody testing, which all use antibodies as markers to diagnose diseases. Most serology is done on serum (derived from blood), but saliva and semen studies have been done, which are similar.

In serology, what the doctor is looking for is “seroconversion”, which means the development of specific antibodies against, in this case, against an antigen. The antibodies looked for are usually IgM antibodies (produced right after the infection) or IgG antibodies (lasting a long time after an infection). The antigen may or may not be detectable so seroconversion is the only way to confirm whether the person was infected.

In serology testing, the antibody binds to a tagged molecule, such as a fluorescent molecule or other protein that allows the blood to agglutinate, the finding of fluorescence, or other detection mechanisms in identifying the presence of the antibody. This can usually be accomplished in situations following seroconversion because there will be an excess of unbound antibody that will easily bind to a tagging molecule for medical identification. The term “seroreversion” means the person’s antibody count reverts, and is no longer detectable in the serum.

Seroconversion can happen after the patient has had the actual infection or has had an immunization that successfully prevents the initial infection of occurring. It relies on detecting the antibodies that are the “immunological memory” of the individual's immune system after getting the infection or being immunized against the microorganism.

Key Takeaways •

Lab techniques in medical microbiology include microscopy, of which there are many types.

•

Microscopy can be used in looking at viruses, prokaryotic cells, and eukaryotic cells.

•

Cultures can be done on viruses, bacteria, or eukaryotic cells.

•

Serology usually looks for the seroconversion of the individual after an infection or after being immunized against the microorganism.

Quiz 1. Optical microscopy goes by another common name. What is that?

9