History of Medical Microbiology,Basic outline of Medical microbiology

1. MILESTONES IN MEDICAL
MICROBIOLOGY
PREPARED BY:-T.ANUSHYA
II-M.SC.,MICROBIOLOGY
UNDER THE GUIDANCE OF:-
MRS.SELVAJEYANTHI,
ASSISTANT PROFESSOR,
DEPARTMENT OF MICROBIOLOGY,
TIRUPPUR KUMARAN COLLEGE FOR WOMEN,
TIRUPPUR
,

2. Introduction
❑A major milestone in medical microbiology is the Gram stain. In 1884
Hans Christian Gram developed the method of staining bacteria to
make them more visible and differentiated under a microscope.
❑ Medical microbiology, the large subset of microbiology that is applied
to medicine, is a branch of medical science concerned with the
prevention, diagnosis and treatment of infectious diseases.
❑In addition, this field of science studies various clinical applications of
microbes for the improvement of health.
❑here are four kinds of microorganisms that cause infectious
disease: bacteria, fungi, parasites and viruses, and one type of
infectious protein called prion.

4. Cont…
❑A medical microbiologist studies the characteristics of pathogens, their modes
of transmission, mechanisms of infection and growth.
❑Medical microbiologists often serve as consultants for physicians, providing
identification of pathogens and suggesting treatment options.
❑Other tasks may include the identification of potential health risks to the
community or monitoring the evolution of potentially virulent or resistant strains
of microbes, educating the community and assisting in the design of health
practices.
❑ They may also assist in preventing or controlling epidemics and outbreaks of
disease. Not all medical microbiologists study microbial pathology; some study
common, non-pathogenic species to determine whether their properties can be
used to develop antibiotics or other treatment methods.

5. ⮚In 1676, Anton van Leeuwenhoek observed bacteria and other microorganisms, using a single-
lens microscope of his own design.
⮚In 1796, Edward Jenner developed a method using cowpox to successfully immunize a child against
smallpox. The same principles are used for developing vaccines today.
⮚Following on from this, in 1857 Louis Pasteur also designed vaccines against several diseases such
as anthrax, fowl cholera and rabies as well as pasteurization for food preservation.
⮚In 1867 Joseph Lister is considered to be the father of antiseptic surgery. By sterilizing the
instruments with diluted carbolic acid and using it to clean wounds, post-operative infections were
reduced, making surgery safer for patients.
⮚In the years between 1876 and 1884 Robert Koch provided much insight into infectious diseases. He
was one of the first scientists to focus on the isolation of bacteria in pure culture. This gave rise to
the germ theory, a certain microorganism being responsible for a certain disease. He developed a
series of criteria around this that have become known as the Koch's postulates.

6. Cont…
⮚In 1910 Paul Ehrlich tested multiple combinations of arsenic based chemicals on infected rabbits with syphilis.
Ehrlich then found that arsphenamine was found effective against syphilis spirochetes. The arsphenamines
was then made available in 1910, known as Salvarsan.
⮚In 1929 Alexander Fleming developed the most commonly used antibiotic substance both at the time and
now: penicillin.
⮚In 1939 Gerhard Domagk found Prontosil red protected mice from
pathogenic streptococci and staphylococci without toxicity. Domagk received the Nobel Prize in physiology, or
medicine, for the discovery of the sulfa drug.
⮚DNA sequencing, a method developed by Walter Gilbert and Frederick Sanger in 1977,caused a rapid
change the development of vaccines, medical treatments and diagnostic methods. Some of these include
synthetic insulin which was produced in 1979 using recombinant DNA and the first genetically engineered
vaccine was created in 1986 for hepatitis B.
⮚In 1995 a team at The Institute for Genomic Research sequenced the first bacterial genome; Haemophilus
influenzae. A few months later, the first eukaryotic genome was completed. This would prove invaluable for
diagnostic techniques.

7. COMMONLY TREATED INFECTIOUS DISEASE:-
BACTERIAL VIRAL FUNGAL
Streptococcal pharyngitis Hepatitis c Candida
Chlamydia Humanpapilomavirus Histoplasmosis
Typhoid fever Parasitic Dandruff
Tuberculosis Malaria
Giardia lamblia
Toxoplasma gondii

8. Causes and Transmission of
Infectious Disease:-
❖Infections may be caused by bacteria, viruses, fungi,
and parasites. The pathogen that causes the disease may be
exogenous (acquired from an external source;
environmental, animal or other people, e.g. Influenza) or
endogenous (from normal flora e.g. Candidiasis).
❖The site at which a microbe enters the body is referred to as
the portal of entry. These include the respiratory
tract, gastrointestinal tract, genitourinary tract, skin,
and mucous membranes.
❖The portal of entry for a specific microbe is normally
dependent on how it travels from its natural habitat to the
host.

10. There are various ways in which disease can be
transmitted between individuals. These include:
❑Direct contact - Touching an infected host, including sexual contact
❑Indirect contact - Touching a contaminated surface
❑Droplet contact - Coughing or sneezing
❑Fecal–oral route - Ingesting contaminated food or water sources
❑Airborne transmission - Pathogen carrying spores
❑Vector transmission - An organism that does not cause disease itself but transmits
infection by conveying pathogens from one host to another
❑Fomite transmission - An inanimate object or substance capable of carrying infectious
germs or parasites
❑Environmental - Hospital-acquired infection (Nosocomial infections)

11. Diagnostic test:-
❖Identification of an infectious agent for a minor illness can be as simple as clinical
presentation; such as gastrointestinal disease and skin infections.
❖ In order to make an educated estimate as to which microbe could be causing the
disease, epidemiological factors need to be considered; such as the patient's likelihood
of exposure to the suspected organism and the presence and prevalence of a microbial
strain in a community.
❖Diagnosis of infectious disease is nearly always initiated by consulting the patient's
medical history and conducting a physical examination.
❖ More detailed identification techniques involve microbial
culture, microscopy, biochemical tests and genotyping.
oOther less common techniques (such as X-rays, CAT scans, PET scans or NMR) are
used to produce images of internal abnormalities resulting from the growth of an
infectious agent.

13. Microbial culture:-
❖Microbiological culture is the primary method used for isolating
infectious disease for study in the laboratory.
❖Tissue or fluid samples are tested for the presence of a
specific pathogen, which is determined by growth in a selective
or differential medium.
Fig shows: Four nutrient agar plates growing colonies of
common Gram negative bacteria.

14. The 3 main types of media used for testing are:
•Solid culture: A solid surface is created using a mixture of nutrients, salts and agar. A
single microbe on an agar plate can then grow into colonies (clones where cells are
identical to each other) containing thousands of cells. These are primarily used to culture
bacteria and fungi.
•Liquid culture: Cells are grown inside a liquid media. Microbial growth is determined by
the time taken for the liquid to form a colloidal suspension. This technique is used for
diagnosing parasites and detecting mycobacteria.
•Cell culture: Human or animal cell cultures are infected with the microbe of interest.
These cultures are then observed to determine the effect the microbe has on the cells.
This technique is used for identifying viruses.

15. Microscopy:-
⮚Culture techniques will often use a microscopic examination to
help in the identification of the microbe.
⮚ Instruments such as compound light microscopes can be
used to assess critical aspects of the organism.
⮚ This can be performed immediately after the sample is taken
from the patient and is used in conjunction with biochemical
staining techniques, allowing for resolution of cellular features.
⮚ Electron microscopes and fluorescence microscopes are also
used for observing microbes in greater detail for research.

16. Biochemical Test:-
❑Fast and relatively simple biochemical tests can be used to identify infectious
agents
❑. For bacterial identification, the use of metabolic or enzymatic characteristics
are common due to their ability to ferment carbohydrates in patterns
characteristic of their genus and species.
❑ Acids, alcohols and gases are usually detected in these tests when bacteria are
grown in selective liquid or solid media, as mentioned above.
❑In order to perform these tests en masse, automated machines are used.
❑ These machines perform multiple biochemical tests simultaneously, using cards
with several wells containing different dehydrated chemicals.
❑The microbe of interest will react with each chemical in a specific way, aiding in
its identification.

17. Serological method:-
❑Serological methods are highly sensitive, specific and often extremely rapid laboratory
tests used to identify different types of microorganisms.
❑ The tests are based upon the ability of an antibody to bind specifically to an antigen.
❑ The antigen (usually a protein or carbohydrate made by an infectious agent) is bound
by the antibody, allowing this type of test to be used for organisms other than bacteria.
❑ This binding then sets off a chain of events that can be easily and definitively
observed, depending on the test. More complex serological techniques are known
as immunoassays.
❑Using a similar basis as described above, immunoassays can detect or measure
antigens from either infectious agents or the proteins generated by an infected host in
response to the infection.

18. Treatment:-
❑Once an infection has been diagnosed and identified, suitable treatment options must
be assessed by the physician and consulting medical microbiologists.
❑ Some infections can be dealt with by the body's own immune system, but more serious
infections are treated with antimicrobial drugs.
❑ Bacterial infections are treated with antibacterials (often called antibiotics)
whereas fungal and viral infections are treated
with antifungals and antivirals respectively.
❑ A broad class of drugs known as antiparasitics are used to treat parasitic diseases.
❑Medical microbiologists often make treatment recommendations to the patient's
physician based on the strain of microbe and its antibiotic resistances, the site of
infection, the potential toxicity of antimicrobial drugs and any drug allergies the patient
has.

19. ❑In addition to drugs being specific to a certain kind of organism (bacteria, fungi, etc.),
❑some drugs are specific to a certain genus or species of organism, and will not work on
other organisms. Because of this specificity, medical microbiologists must consider the
effectiveness of certain antimicrobial drugs when making recommendations.
❑ Additionally, strains of an organism may be resistant to a certain drug or class of drug,
even when it is typically effective against the species. These strains, termed resistant
strains, present a serious public health concern of growing importance to the medical
industry as the spread of antibiotic resistance worsens. Antimicrobial resistance is an
increasingly problematic issue that leads to millions of deaths every year.

20. Cont…
❑Microbes have been shown to be helpful in combating infectious disease and
promoting health.
❑Treatments can be developed from microbes, as demonstrated by Alexander Fleming's
discovery of penicillin as well as the development of new antibiotics from the bacterial
genus Streptomyces among many others.
❑Not only are microorganisms a source of antibiotics but some may also act
as probiotics to provide health benefits to the host, such as providing better
gastrointestinal health or inhibiting pathogens.
❑ Medical microbiology is not only about diagnosing and treating disease, it also involves
the study of beneficial microbes.

21. ❑ https://en.m.Wikipedia.org/wiki/medical_microbiology#