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Clinical microbiology

What is the the Clinical Microbiology? It is the part of the microbiology that are studied the interaction between microorganism and microorganisms in norm and pathology, in the dynamics of the inflammation processes taking into account conduct therapy to the convalescence.
What is the aim of the Clinical Microbiology? To study the interaction between microorganism and microorganisms in norm and pathology, in the dynamics of the inflammation processes taking into account conduct therapy to the convalescence.
What are the tasks of the Clinical Microbiology? · To study the biology and meaning of the non-pathogenic microorganisms in the aetiology end pathogenesis of the pus-inflammatory disease. · Working out and using of the microbiology diagnosis method, therapy and prevention of the infection diseases that are founded in non-infectious department. · To researchers the microbiologic problems of the hospital infections, dibacteriosis, drug –fast of the microbes. · Microbiologic substantiation and microbiologic control of the antimicrobial measures in hospitals.
What is non-pathogenic microorganism? These are the microorganisms that have small degree of the pathogenicity for human and may cause the diseases in definite conditions.
What non-pathogenic microorganisms may be the causative agents of the opportunistic infections?   1. Bacteria (Escherichia, Staphylococcus, Pseudomonas, Klebsiella, Streptococcus, Haemophilus, Listeria, Legionella, Mycoplasma, Mycobacterium at all). 2. Fungi (Candida, Aspergillus, Cryptococcus). 3. Virus (Herpes, Adenovirus, Papova, ECHO, Koksaki). 4. Invasions (Pneumocysta, Toxoplasma).
The determination of the opportunistic infections. It is the diseases that are arise in immunocomprimised patients and caused non-pathogenic microorganisms.
The arising conditions of the opportunistic infections. Opportunistic infections are arising only in immunodeficient patients. Some factors such as properties of microorganisms, state of the human body, condition of them interaction, way of penetration, decreasing of the body stability, influence on the development and course of the opportunistic infections.
The futures of the opportunistic infections. · The source of infection is patients, bacteria-carrier, animals and object of the surroundings. · The causation agents may affect different organs and systems, its may transmission any ways. ·All opportunistic infections arising in immunocompromised patients. · It is endogen infections. · This illness is taking its mixinfections and chronic. · Its have tendencies to generalisations and bed treated. · Opportunistic infections are widely spread in hospitals and often bind with giving of medical help.
Mixinfections. It is infection that are caused some species if microbes.
Disbacteriosis. It is the state that develops in result of the dysfunction normal flora.
Heterogeneity of the bacteria’s population.   The parasites population is heterogeneity. Microbes’ one species have genomic and phenotypic heterogeneity. All microbes one species may subdivide on the higly-, gently, weakly-, avirulents.
The determination of the hospital infections. It is the infection infecting of which takes a place in medical establishments. It which accumulate an infection on a basic disease and complicates his clinical flow.
The classification of the hospital infections. Septicemia, pus-inflammatory after-effect of the wounds and burns, acute intestinal, respiratory, urogenitat, post transfusion infection and disease caused using of antibiotics.
The conditions that are promoting arising of the of the hospital infections. Exciters: their amount, level pathogenicity, changeability. Macroorganism: if people are a risk group, immunodeficient people, oncologic patients, children, people of superannuated, ambustial patients, patient after operating interferences, people with saccharine diabetes.
What is listeriosis? It is disease that are caused by L. monocytogenes and the rare species L. ivanovii. The designation L. monocytogenes results from the observation that infections of rodents, which are much more susceptible than humans, are accompanied by a monocytosis.
Morphology and culturing of the listeriosis’s causative agents. The small Gram-positive rods feature peritrichous flagellation. They show greater motility at 20 °C than at 37 °C. Culturing is most successful under aerobic conditions on blood agar. Following incubation for 18 hours, small gray colonies surrounded by inconspicuous hemolytic zones appear. The zones are caused by listeriolysin O. Listeriae can also reproduce at 5–10 °C, which fact can be used in their selective enrichment (“cold enrichment”).
Pathogenesis of the listeriosis. Adherence to phagocytic cells (e.g., macrophages) and nonphagocytic cells (e.g., enterocytes). Invasion by endocytosis, induced by the protein internalin on the surface of the listeriae. Formation of the endosome. Destruction of the endosome. The virulence factor listeriolysin forms pores in the endosomal membrane, releasing the listeriae into the cytoplasm. Replication of the listeriae in the cytoplasm of infected cells. Local intercellular dissemination. Polymerization of the actin of infected cells at one pole of the listeriae to form so-called actin tails that move the listeriae toward the membrane. Formation of long membrane protuberances (known as listeriopods) containing listeriae. Neighboring cells engulf the listeriopods, whereupon the process of listeria release by means of endosome destruction is repeated. Dissemination is generally by means of hematogenous spread.
Clinical characteristics. Listeriae are classic opportunists. The course of most infections is clinically silent. Symptoms resembling a mild flu do not occur in immunocompetent persons until large numbers of pathogens (106–109) enter the gastrointestinal tract with food. Massive infections frequently cause symptoms of gastroenteritis. Listeriosis can take on the form of a sepsis and/or meningoencephalitis in persons with T cell defects or malignancies, in alcoholics, during cortisone therapy, during pregnancy, in elderly persons and in infants. Congential listeriosis is characterized by sepsis with multiple abscesses and granulomas in many different organs of the infant (granulomatosis infantiseptica). The lethality rate in severe cases of listeriosis varies between 10% and 40%. The incubation period can vary from one to three days to weeks. Diagnosis requires pathogen identification by means of microscopy and culturing.
Epidemiology and prevention. Listeriae occur ubiquitously in soil, surface water, plants, and animals and are found with some frequency (10%) in the intestines of healthy humans. Despite the fact that contact with listeriae is, therefore, quite normal and even frequent, listeriosis is not at all common. The incidence of severe infections is estimated at six cases per 106 inhabitants per year. Occurrence is generally sporadic. Small-scale epidemics caused by food products—such as milk, milk products (cheese), meat products, and other foods (e.g., coleslaw)—contaminated with very high numbers of listeriae have been described. Preventive measures include proper processing and storage of food products in keeping with relevant hygienic principles.
Therapy. Amoxicillin, penicillin G, or cotrimoxazole.
What is Legionnaire’s Disease? It is disease that are caused by Legionella pneumophila.
Morphology and culturing of the Legionella pneumophila.. Legionellae is difficult to stain. They are Gram- negative, aerobic bacteria. L. pneumophila is a rod bacterium 0.3–1 µm wide and 2–20 µm long. They can be rendered visible by means of direct immunofluorescence. Legionella grow only on special mediums in an atmosphere containing 5% CO2.
Classification. Legionella bacteria were discovered in 1976, occasioned by an epidemic among those attending a conference of American Legionnaires (former professional soldiers). They are now classified in the family Legionellaceae, which to date comprises only the genus Legionella. This genus contains numerous species not listed here. Most human infections are caused by L. pneumophila, which species is subdivided into 12 serogroups. Human infections are caused mainly by serogroup 1.
Epidemiology The species Legionella pneumophila is responsible for most legionelloses in humans. Infections with the natural habitat of legionellae are damp biotopes. The sources of infection listed in the literature include hot and cold water supply systems, cooling towers, moisturizing units in air conditioners, and whirlpool baths. Legionelloses can occur both sporadically and in epidemics.
Pathogenesis. Legionella occur when droplets containing the pathogens are inhaled. Two clinically distinct forms are on record: legionnaire’s disease leading to a multifocal pneumonia and nonpneumonic legionellosis or Pontiac fever. The persons most likely to contract legionnaire’s disease are those with a primary cardiopulmonary disease and generally weakened immune defenses. The pathomechanisms employed by legionellae are not yet fully clarified. These organisms are facultative intracellular bacteria that can survive in professional phagocytes and in alveolar macrophages. They are capable of preventing the phagosome from fusing with lysosomes. They also produce a toxin that blocks the oxidative burst.
Clinical picture Two clinical forms of legionellosis have been described: · Legionnaire’s disease results from inhalation of droplets containing the pathogens. The incubation period is 2 to 10 days. The clinical picture is characterized by a multifocal, sometimes necrotizing pneumonia. Occurrence is more likely in patients with cardiopulmonary primary diseases or other immunocompromising conditions. Lethality >20%. · Pontiac fever is named after an epidemic in Michigan. Incubation period 1 to 2 days. Nonpneumonic, febrile infection. Self-limiting. Rare.
Diagnosis. Laboratory diagnostic methods include microscopy with direct immunofluorescence, culturing on special mediums and antibody assays. Specific antibodies marked with fluorescein are used to detect the pathogens in material from the lower respiratory tract. For cultures, special culture mediums must be used containing selective supplements to exclude contaminants. The mediums must be incubated for three to five days. Legionella antigen can be identified in urine with an EIA. A gene probe can also be used for direct detection of the nucleic acid (rDNA) specific to the genus Legionella in the material. Antibodies can be assessed using the indirect immunofluorescence technique.
Therapy. The antibiotics of choice are the macrolides.
Prevention. Human-to-human transmission has not been confirmed. Legionella bacteria tolerate water temperatures as high as 50 °C and are not killed until the water is briefly heated to 70°C.

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Date: 2016-01-14; view: 719


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CLINICAL MICROBIOLOGY | Microbiological research of the Legionella infection
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