«Rickettsiaceae. Chlamydiae. Mycoplasmas. Orthomyxovirus.Paramyxovirus».

1. Rickettsiaceae.

 

Morphology.

Rickettsiae are small, Gram negative bacteria. They are obligate intracellular parasites, nonmotile, noncapsulated and nonsporing.

Cultural characteristics.

Rickettsiae are able to grow in:

Organism of laboratory animals (such as guinea pigs).

Yolk sac of developing chick embryos.

Cell culture (Hela, Hep-2).

2. Typhus fever.

R.prowazekii – agent of epidemic typhus fever and recrudescent typhus (Brill disease).

R.typhi – agent of endemic typhus fever.

Pathogenicity.

1. Adhesion.

2. Invasion.

3. Toxin – thermostable toxic protein.

Epidemic typhus.

The source of infection: patient.

The human body louse Pediculus humanus corporis is the vector. The head louse may also transmit the infection.

Endemic typhus.

The source of infection: rats.

Infection transmitted by the rat flea.

Pathogenesis and clinical symptoms.

The incubation period is 10-12 days.

Adhesion Rickettsia on cells of vascular wall

↓

Invasion

↓

Myltiply

↓

Damage other endothelial cells

↓

Perivasculitis, thrombosis.

The disease sterts with fever and chills. A characteristic rash appears on the fourth or fifth day, starting on the trunk and spreading over the limbs but sparing the face, palms and soles. Towards the second week, the patient becomes stuporous and delirious.

Laboratory diagnosis.

The main method – serological.

Material for diagnostics – serum.

Classical complex of serological reaction.

1. Complement fixation test.

2. Reaction passive hemagglutination.

3. EIA.

4. Immunofluorescence test.

In some who recover from the disease, the rickettsiae may remain latent in the lymphoid tissues, or organs for years. Such latent infection may, at times, be reactivated leading to recrudescent typhus (Brill disease).

For differentiation between epidemic typhus and Brill disease use reaction passive hemagglutination.

Specific prophylaxis.

1. Live typhus vaccine.

2. Chemical typhus vaccine from protective antigen of R.prowazekii.

3. Agent of Q-fever, diagnostics of disease. Specific prophylaxis.

Agent of Q-fever – Rickettsia which named Coxiella burnetti.

The source of infection:

1. Domastic animals (cattle, house, swine, etc).

2. Wild animals, rodents, birds.

3. Ticks.

The mode of infection.

1. By ingestion of contaminated food (milk and meat).

2. Direct contact with infected animals.

3. Through tick bites.

4. Droplet infection.

Pathogenesis and clinical symptoms.

The human disease is an acute systemic infection characterised by an interstitial pneumonia. The clinical picture is very variable and asymptomatic infections very common. In chronic q-fever, the coxiella spreads through almost all organs and may cause hepatitis, meningoencephalitis or endocarditis. Spontaneous recovery is usual. The coxiella may remain latent in the tissues of patients for 2-3 years.

Cox.burnetii is an obligate intracellular pathogen, primarily infecting the monocytemacrophage cells.

Laboratory diagnosis.

1. Serological method (main)  - complement fixation test, EIA, RPHA.

2. Allergological method – with dissoluble antigen of C.burnetii (for retrospective diagnostics).

Specific prophylaxis.

Live cutaneous vaccine Q-fever M-44.

4. Chlamydiae.

Chlamydiae are obligate intracellular bacterial parasites of humans. Unlike other bacteria, they do not have peptidoglycan cell walls. They lack enzymes of the electron transport chain and so require ATP and nutrient resources from host cells. They have therefore been called energy parasites.

The main morphological forms of chlamydiae.

Characteristic	Elementory body	Reticulate body
Shaped	Spherical	Ovoid
Size	Small (0,2-0,3mkm)	Large (0,8-1,5mkm)
Infectivity	Infective form	Non-infective form
The mode of existence in the macroorganisms	Extracellular form	Intracellular growing and replicative form

Reproductive cycle of chlamydia.

1. Elementory body (EB).

2. EB enters cell by endocytosis.

3. EB reorganised into reticulate body (RB).

4. RB undergoing fission.

5. Developing EB from RB.

6. Death and lysis of cell releasing EB.

Pathogenicity.

1. Adhesion (by membrane proteins).

2. Invasion (by endocytosis).

3. Surface antigens.

4. Exo- and endotoxins.

Genus Chlamydiae contains three species:

Cl.trachomatis (15-18 serovars)

Cl.psittaci

Cl.pneumonia

C.trachomatis may be cause next disease:

1. Trachoma

2. Paratrachoma

3. Genital chlamydiasis

4. Infection of newborn

5. Lymphogranuloma venereum

The source of infection: patient or bacteriocarrier.

Trachoma.

Agent: Cl.trachomatis (serovars A, B, C).

Trachoma is a chronic keratoconjunctivitis, characterised by follicular hypertrophy, papillary hyperplasia, pannus formation and in the late stages, cicatrisation.

The mode of infection: contact. Infection is transmitted from eye-to-eye by fingers or fomites.

Paratrachoma.

Agents: Cl.trachomatis (serovars D, E, K).

The mode of infection: contact.

Clinical form: conjunctivitis, without cicatrization.

Genital infections.

Agents: Cl.trachomatis (serovars D, E, K).

The mode of infection: sexually transmitted.

Clinical symptoms:

In men, they cause urethritis, epididymitis, proctitis, conjunctivitis and Reiter syndrome (Reiter syndrome is a triad of recurrent conjunctivitis, polyarthritis and urethritis or cervicitis).

Women develop acute urethral syndrome, mucopurulent cervicitis, endometritis, salpingitis. Genital chlamydiasis may cause infertility, ectopic pregnancy, premature deliveries, etc.

Infection of newborn.

Agents: C.trachomatis (serovars D, E, K).

The mode of infection: Transplacental transmission, intranatal.

Clinical forms: conjunctivitis and interstitial pneumonia.

Lymphogranuloma venereum.

Agents: Cl.trachomatis (serovars L1-L3).

The mode of infection: sexual contact.

Clinical symptoms: suppurative inguinal adentitis.

Laboratory diagnosis:

Material for diagnostics	Method of diagnostics	Results
Scrape of epithelium mucous membrane of urethra, cervical canal, conjunctiva, puncture of lymph nodes.	Microscopic method	Direct microscopy with Romanovsky-Giemsa stained smears where cytoplasmic inclusion body (Halberstaedter-Prowazek body) may be seen. This inclusion body have blue-violet colour.
	Immunofluorescence test (direct and indirect)	By monoclonal antibody reveal chlamydiae antigens.
	Genetic method (PCR)	DNA probes.
Serum	Serological method (EIA, immunofluorescence test (indirect), reaction passive hemagglutination.	Determination of IgM and IgG to chlamydiae.

Ornithosis.

Agent: C.psittaci.

The source of infection: domastic and wild birds (turkey, durk, gooses, rarely – pigeon and parrot).

The mode of infection: droplet infection.

Clinical symptoms: high temperature, headache, dry cough.

Laboratory diagnosis:

1. Serological method (main) – complement fixation test, reaction passive hemagglutination, immunofluorescence test.

2. Allergological method – cutaneous test with ornithin.

Respiratory chlamydiosis.

Agent:C.pneumoniae.

The source of infection: patient.

Clinical forms: pharyngitis, bronchitis, bronchopneumonia.

Laboratory diagnosis:

1. Microscopic method.

2. Immunofluorescence test.

3. Serological method – EIA (for detrmination IgM).

5. Mycoplasmas.

Mycoplasmas are a group of bacteria that are devoid of cell wall and so pleomorphic, with no fixed shape or size. They are Gram negative, nonsporing, noncapsulated.

Mycoplasmas may be cultivated in fluid or solid media with blood. The colony is typically biphasic, with a «fried egg» appearance, consisting of a central opaque granular area of growth extending into the depth of the medium, surrounded by a flat, translucent peripheral zone.

Pathogenicity.

1. Adhesion.

2. Toxins:

Hemolysins

Protein toxins, which damage epithelium of respiratory tract (M.pneumoniae).

3. Enzymes:

Protease (M.hominis, Ureaplasma urealyticum).

Neuraminidase (M.pneumoniae).

DNA-ase, RNA-ase.

Very importance in the pathology of human have 4 species of Mycoplasmas:

M.pneumoniae

M.hominis

M.genitalium

Ureaplasma urealyticum.

M.pneumoniae – agent of respiratory mycoplasmosis.

M.hominis and U.urealyticum – agent of urogenital infections. Such as: urethritis, cystitis, prostatitis, endometritis, salpingitis.

Material for diagnostics: sputum, urine, serum, urethral discharge, vaginal discharge, etc.

Laboratory diagnosis.

1. Genetic method (PCR).

2. Serological method – immunofluorescence test (direct and indirect).

3. Bacteriological method.

6. Acute respiratory disease.

Acute respiratory disease (ARD) may be cause bacteria and viruses.

Acute virus respiratory disease (AVRD) cause only viruses.

Clinical forms of ARD: rhinitis, pharyngitis, laryngitis, tracheitis, bronchitis, conjunctivitis, pneumonia.

Agents and diagnostics of AVRD.

Viruses	Method of diagnostics	Material for diagnostics
1. influenza virus (A,B,C) 2. parainfluenza virus 3. respiratory syncytial virus (RSV) 4. rhinovirus 5. enterovirus Coxsackie virus A Coxsackie virus B Echovirus 6. coronavirus 7. reovirus 8. adenovirus	1. Express – diagnostics: Rhinocytoscopia Immunofluorescence test EIA	1. Films from mucous membrane of nose. 2. Wash-out from nasopharynx.
	2. Virological method	1. Wash-out from nasopharynx.
	3. Serological method	3. Serum

 Bacteria – agent of ARD:

Mycoplasma pneumoniae

Clamydiae psittaci

Clamidiae pneumoniae

Coxiella burnetii

Legionella pneumophila

Haemophilus influenzae

Klebsiella pneumoniae

Streptococcus pneumoniae

7. Influenza.

Families – Orthomyxoviridae. The virus core consists of ribonucleoprotein in helical symmetry. The RNA is surrounded by an envelope, which has an inner membrane protein layer (capsid) and an outer lipid layer (supercapsid or peplos).

On surface of peplos found glicoproteins: hemagglutinin (H) and neuramimidase (N).

Influenza virus cultivation in chick embryos.

Antigenic structure:

1. Nucleoprotein (RNA + capsid) – influenza viruses are classified into types A, B and C by nucleoprotein Ag.

2. Surface antigens (hemagglutinin and neuraminidase).

 Human influenza viruses have 4 antigenic types of hemagglutinins (H0, H1, H2, H3) and 2 types neuraminidases (N1, N2).

Influenza virus A are classified into subtypes by H and N. For example: A(H1N1), A(H3N2), etc.

Influenza virus types B and C haven t subtypes.

   Antigenic variation:

The partial change in surface antigenic structure of influenza virus type A occuring regularly at frequent intervals is known as antigenic drift. Appear new strans of virus in the results

Antigenic shift, on the other hand, is a total variation in the surface antigenic structure, resulting in a novel virus strain unrelated antigenically to predecessor subtype. Such changes may involve hemagglutinin, neuraminidase or both.

The source of infection: patient.

The mode of infection: droplet infection.

Pathogenesis:

Virus adhesion to epithelial cells of respiratory tract (by hemagglutinin)

↓

Reproduction of virus in this cells

↓

Death of cell releasing virus (by neurominidase)

↓

virus appear in the blood

↓

damage cells of endothelium of capillary vessels.

Laboratory diagnosis:

Material for diagnostics: wash-out from nasopharynx, films from mucous membrane of nose.

1. Express-diagnostics:

Rhinocytoscopia films from mucous membrane of nose.

Immunofluorescence test

EIA

2. Virological method. The virus multiply well in the amniotic cavity of chick embryos. Indication and identification by reaction hemagglutination (RHA) and reaction stopping hemagglutination (RSHA).

3. Serological method – CFT, RSHA.

Specific prophylaxis.

Inactivated and chemical vaccine (from strains A(H1N1), A(H3N2), B):

1. inactivated influenza vaccine (fluid)

2. «Subunit» vaccine (Grippol).

3. Split – vaccine (Vacsigripp).

Live vaccine (from attenuated strains):

1. Live influenza vaccine from strains A(H1N1), A(H3N2).

2. Live influenza vaccine from strains A(H1N1), A(H3N2), B.

8. Parainfluenza.

Families – Paramyxoviridae. The virus core consists of RNA. The nucleocapsid is surrounded by a lipid envelope (supercapsid or peplos). On surface of peplos found glycoproteins: HN-protein and F-protein (for adhesion on the cells of respiratory tract and invasion).

Parainfluenza virus cultivation in cell culture.

The source of infection: patient.

The mode of infection: droplet infection.

Clinical forms: for adult – laryngitis, for children – laryngotracheobronchitis → edema of larynx.

Laboratory diagnosis:

1. Express dignostics (such as for influenza).

2. Virological method.

3. Serological method (CFT and NT).

9. Respiratory syncytial virus (RSV).

Families – Paramyxoviridae. The virus core – RNA. The RNA is surrounded by an envelope, which has an inner and outer membranes (capsid and supercapsid). On surface of supercapsid found F-protein.

RSV cultivation in cell culture.

The source of infection: patient.

The mode of infection: droplet infection.

    For adult and children – AVRD.

  Laboratory diagnosis:

 1. Express diagnostics – IFT, EIA.

  2. Virological method.

   3. Serological method – CFT, NT.