Презентация на тему Introduction to special microbiology

and their use in dentistry

studies the morphology, ecology, genetics 
and biochemistry of bacteria and their relation to medicine
This subdivision of microbiology involves

the identification, classification, and characterization of bacterial species

genetic material contained in a protein coat – and virus-like

agents
It focuses on the following aspects of viruses: their structure, classification and evolution, their ways to infect and exploit host cells for reproduction, their interaction with host organism physiology and immunity, the diseases they cause, the techniques to isolate and culture them, and their use in research and therapy
Virology is considered to be a subfield of microbiology or of medicine

to be identified clinically. Most pathogens, however, can cause

a wide spectrum of clinical syndromes in humans. Conversely, a single clinical syndrome may result from infection with any one of many pathogens. Influenza virus infection, for example, causes a wide variety of respiratory syndromes that cannot be distinguished clinically from those caused by streptococci, mycoplasmas, or more than 100 other viruses.

to use microbiologic laboratory methods to identify a specific

etiologic agent. Diagnostic medical microbiology is the discipline that identifies etiologic agents of disease. The job of the clinical microbiology laboratory is to test specimens from patients for microorganisms that are, or may be, a cause of the illness and to provide information (when appropriate) about the in vitro activity of antimicrobial drugs against the microorganisms identified 

of infectious disease with a bacterial etiology
From: Chapter 10, Principles

of Diagnosis
Medical Microbiology. 4th edition.
Baron S, editor.
Galveston (TX): University of Texas Medical Branch at Galveston; 1996.

the test material; the study of their morphological and

tinctorial properties, the nature of their location in the bacteriological smear in the field of vision
The study is appointed if there is a suspicion of the patient having an infectious and purulent-inflammatory process or in the obstetric and gynecological area

a portion is selected in which the causative agent

of the disease (lumps of mucus, purulent plugs) can be detected with the greatest probability.
It is applied to a slide.
The drop is spread over the glass, dried and fixed.
The smear stains (by Gram method) and the drug is examined under a microscope.

accessibility
DISADVANTAGES
To determine the type of microorganisms, it is often

insufficient to determine its morphological properties
Bacteria with characteristic morphology often undergo changes, especially under the action of antibiotics, and become unrecognizable
Concentration of pathogens in the test material can be extremely low, and then they are difficult to detect

pure culture of the pathogen (a population containing bacteria

of one species) and identifying this pathogen
A multi-stage bacteriological study lasts 18-24 hours
Identification is the study of the properties of microorganisms so establishing a particular systematic group of bacteria (species, genus)
This method is used in to determine such dangerous diseases as tuberculosis, recurrent typhoid or gonorrhea. It is also used to study the bacterial composition of tonsils, cavities of organs

test material on dense nutrient media, elective or differential-diagnostic

which is placed in thermostat)
The study of bacterial colonies grown on a dense nutrient medium and originating from a single bacterial cell (the colony is a pure culture of the pathogen):
– cultural properties of the colonies (shape, size, color, edges and surfaces, structure, consistency)
– tinctorial and morphological properties of the selected culture and verifying at the same time its purity
Identification of the isolated pure culture of the pathogen and determination of its sensitivity to antibiotics and other chemotherapeutic drugs

to apply the most effective treatment by accurately determining

the reaction of microorganisms to a particular medical device
DISADVANTAGES
Lasts a long time
Strict requirements to test material
Strict requirements for laboratory technicians

antibodies or antigens in the blood serum of patients

based on the reactions of immunity. With their help, antigens of microbes or tissues are also identified for the purpose of their identification.
The detection of antibodies to the infectious agent or the corresponding antigen in the serum of the patient allows to establish the cause of the disease.
Serological studies are also used to determine blood group antigens, tissue antigens and the level of humoral immunity.

such dangerous diseases as HIV, hepatitis, brucellosis, STDs
High specificity

and sensitivity
Most of the reactions of this method are simple in conducting and accounting, available to a wide range of laboratories, usually safe, economical, amenable to standardization
DISADVANTAGES
the indirect nature of the result, when the etiology of the disease is judged not by the isolation of the pathogen, but by the immune response to the causative agent
the need for parenteral intervention in the patient's body
in most cases, late diagnosis, which is due to the natural dynamics of the humoral immune response

of diagnosing allergic and infectious diseases, in the pathogenesis

of which the allergic component predominates
are based on the local or general reaction of the sensitized organism in response to the introduction of a specific allergen – a delayed type hypersensitivity reaction (HRT)
are used for detection of an allergen or a group of allergens that have caused a hypersensitivity state
Skin tests (application, scarification and intradermal tests) provocative tests (nasal, conjunctival, inhalation)

activation of cellular immunity, an increased sensitivity of the

organism to pathogens and products of their vital activity develops. This is based on allergic tests used to diagnose bacterial, viral, protozoal infections, mycoses and helminthiases. Allergic tests have specificity, but often they are positive for those who have recovered and vaccinated.

delayed type hypersensitivity (HRT), scheme
Introduction intradermally Ag bacteria
After 48

- 72 hours there is inflammation
Measure the amount of redness and papules

reaction)
brucellosis (Burne test)
tularemia (Tularin test)
anthrax (anthraxin test)
soft chancre (Duchess

reaction)
leprosy (Mitsuda reaction)
differentiate tuberculoid (lepromin-positive) form from lepromatous (lepromin-negative)

infected, but also in vaccinated against these diseases, as

well as in people who have recovered many years ago
many patients the method of introducing an irritant into the body is contraindicated

determining the presence of pathogen toxins in the test

material and on the detection of the causative agent. Methods include infecting laboratory animals with the test material, followed by isolation of a pure pathogen culture or establishing the presence of a microbial toxin and its nature. The method is highly sensitive, can be used in the early stages of the disease, but is not always available, expensive, long-lasting, unsafe.

of nucleic acids, first of all, the DNA molecule
The

advantage of DNA diagnostics in comparison with biochemical or immunological diagnostics is the use of a unified set of methods that is practically independent of the objectives of the study. These are methods for DNA isolation, PCR, electrophoresis, DNA restriction, hybridization with specific DNA probes, and sequencing. Thus, within the limits of one laboratory it is possible to be engaged in DNA-diagnostics of a wide spectrum of diseases

DNA probe will bind to the specimen if it

contains the specific sequence that is being sought. The captured probe is detected by the activity of it attached label. This technique is specific and rapid, but less sensitive than other methods that involve amplification steps.

tests (NAATs) make the diagnosis by amplifying specific regions

of the genome from the pathogen. Although different methods are used to amplify pathogen-specific DNA or RNA the aim is the same, to produce sufficient copies for detection. For example, nucleic acid from the pathogen is separated into single strands and primers are designed to bind to targetsequences. A polymerase then catalyses synthesis of new nucleic acid and this process is repeated for multiple cycles.

commercial kits have made these tests available in many

laboratories. Real-time PCR machines measure rising concentrations of target DNA and determine positivity when the concentration passes a set threshold.
NAATs have the advantage that they can detect slow-growing organisms or those that are difficult to grow (e.g. M. tuberculosis) or make a diagnosis when samples are rendered falsely negative by antibiotic therapy.

used in molecular biology to amplify (accumulate of copies of a certain

nucleotide sequence) a single copy or a few copies of a segment of DNA across several orders of magnitude, generating thousands to millions of copies of a particular DNA sequence
Very sensitive method

a DNA fragment specific for a particular pathogen is

amplified, and then, with the help of electrophoresis and staining on DNA, the presence of this fragment, and therefore of the pathogen itself, is tested in the biological sample that was taken for analysis.

POLYMERASE CHAIN REACTION

thermophilic bacteria, because they are thermostable
The three-dimensional structure of

DNA-binding helical-hairpin sites in human beta-DNA polymerase

a 100 μl reaction mixture
Placing a strip of eight PCR

tubes into a thermal cycler

analysis of macromolecules (DNA, RNA and proteins) and their fragments, based on

their size and charge. It is used in clinical chemistry to separate proteins by charge and/or size (IEF agarose, essentially size independent) and in biochemistry and molecular biology to separate a mixed population of DNA and RNA fragments by length, to estimate the size of DNA and RNA fragments or to separate proteins by charge
Nucleic acid molecules are separated by applying an electric field to move the negatively charged molecules through a matrix of agarose or other substances. Shorter molecules move faster and migrate farther than longer ones because shorter molecules migrate more easily through the pores of the gel. This phenomenon is called sieving

is placed in this buffer-filled box and an electrical

field is applied via the power supply to the rear. The negative terminal is at the far end (black wire), so DNA migrates toward the positively charged anode (red wire)

sets of primers were used to amplify a target

sequence from three different tissue samples. No amplification is present in sample #1; DNA bands in sample #2 and #3 indicate successful amplification of the target sequence. The gel also shows a positive control, and a DNA ladder containing DNA fragments of defined length for sizing the bands in the experimental PCRs.

based on the interaction of antigens with antibodies, but

the reagent is then labeled with a dye that glows in the ultraviolet. Luminous antigen-antibody complexes are clearly visible under fluorescence microscopy. It is a rapid and accurate diagnostic method for the detection of antigens of microbes or the detection of antibodies.

test)

in periodontal tissues
In the origin and development of the

pathological process in the tissues of the periodontal disease, the toxic bacteria of the dental plaque, the disturbance of metabolic mechanisms in tissues, the disturbance of hemodynamics, the regulating role of the nervous and endocrine systems, as well as the immune mechanisms of damage, play a major role

person are filled with microflora. Colonies of microorganisms are

concentrated in the surface areas of the gum, as well as on the subgingival dental plaque, where a monolayer with a thickness of up to 20 microbial cells is formed, among which 3/4 are cocci, and 1/4 are rods and spirals.

of cheek cells)
http://microbio146.blogspot.ru/2011/11/lab-35-oral-microbiota.html

both for diagnosis and for the selection of adequate

etiopathogenetic treatment, a microbiological analysis is necessary. Success and failure of treatment often depend on whether it is possible to identify the causative agent of a disease