Host-microbe relationship
From WikiLectures
Relationships of organisms[edit | edit source]
Symbiosis - the coexistence of two or more different organisms.
- Endosymbiosis x ectosymbiosis
- Symbiont – any microorganism that shares at least part of its life with another organism
- Three forms of symbiosis:
- commensalism – benefits the commensal and does not harm the host (normal intestinal flora)
- mutualism – both partners benefit (Escherichia coli and production of vitamin B12 and K, and making colonization by pathogens more difficult)
- parasitism – the organism harms the host - directly or just deprives it of nutrients - intracellular parasites, ectoparasites (lice), endoparasites (tapeworms)
Parasite and saprophyte
- A parasite is an organism that at least sometimes requires another living organism
- Saprophyte - a microbe does not need another organism, it only needs non-living organic matter
- Pathogenic saprophytes – Clostridium botulinum, Histoplasma capsulatum
Infection[edit | edit source]
There are several definitions for the term infection or contagion:
- The presence of a microorganism in a particular host.
- The penetration of an infectious agent into an organism, multiplication inside and adverse effects on its surfaces (in contrast to this stands colonization - colonization by a non-pathogenic or pathogenic microbe without disease symptoms).
- Conflict between a microbe and its host (even in asymptomatic infection).
Process of infection[edit | edit source]
The process and severity of infection can be influenced by several factors:
By the microbe
- pathogenicity;
- virulence;
- infectious dose.
From the macroorganism
- degree of non-specific resistance - overall fitness, genetic factors (population resistance);
- specific immunity - primary, secondary reactions;
- age, nutrition, lifestyle.
Other circumstances
- Environmental influences (e.g. seasonal variations - respiratory infections in cold weather),
- gateway infection (e.g. tularemia).
Stages of infection[edit | edit source]
- Incubation period;
- period of prodromal symptoms - non-specific symptoms;
- typical syndrome;
- recovery - relapse may occur;
- relapse - after recovery.
Forms of infection[edit | edit source]
According to manifestations
- Inaparent.
- Manifest.
- Subclinical - non-characteristic symptoms.
- Abortive - poorly expressed symptoms.
- Clinical form of infection - all symptoms expressed.
According to the range
- Local (possibly also focal).
- Systemic (sometimes referred to as massive) - when it affects the whole system or a substantial part (e.g. influenza, pulmonary TB, meningitis, pyelonephritis...).
- Generalized (regularly e.g. typhoid fever, spotted fever, most exanthematous viruses).
According to the course
- Acute (days).
- Subacute (months).
- Fulminant (violent).
- Chronic (years).
- Asymptomatic chronic infections.
- Mainly viruses, bacteria – Rickettsia prowazekii, Chlamydia trachomatis, Salmonella typhi, Mycobacterium tuberculosis.
- Persistent - agents present in an infectious detectable form.
- Latent - in the body in a non-infectious form.
- Asymptomatic chronic infections.
References[edit | edit source]
Related articles[edit | edit source]
Sources[edit | edit source]
- JANSKÝ, Petr. Zpracované otázky z mikrobiologie [online]. [cit. 2012-02-01]. <https://www.yammer.com/wikiskripta.eu/uploaded_files/3804405>.
