for all the procedure .
1- Air-bone route
2- Fecal-oral route
3- Direct contact
4- Contaminated non-living objects.
These are the basic transmission of infections routes.
Aerosols produced by coughing and sneezing are important in the transmission of tuberculosis. Aerosols containing Legionelaa pneumophilla may be created from cooling towers
and air-conditioning plants. On inhalation the acrosolized particles are not trapped in the upper respiratory tract, but are deposited in the alvoli. This is the portal of entry for this organism. Streptococcus pneumoniae, haemophilus influenzae and viruses which affect he upper respiratory tract are be transmitted by direct inculation on hands contaminated with the nasal mucus from an infected person. A human carrier of slamnella typhi in the gut may inoculate food with the organism during preparation (especially dangerous are not cooked foods like salads). shigella sonnei contaminates the environment around a patient with profuse diarrhea. It is easy for children to
contaminate the hands and put hte finger in the mouth or eat before washing( in school, nurseries).
Certain infections, as the sexually transmitted disease, require close direct contact with infected individuals . Other bacteria may enter a wound at the time of injury like clostridium tetani as a consequence of a dirty injury. Transfer of organisms can also take place by the bite of an animal or insect (malaria, plague etc).
These infections include skin disease form baths, intestinal infections from cutlery, spticemia from intra venus (I.V) fluids and wound infections from contaminated surgical instruments or dressings(pseudomonas).Pathogencity-the ability of bacteria to cause disease. Virulence-degree of pathogenicity, specific properties of bacteria that enhance their ability to cause disease.Bacteria with a high degree of virulence will cause a more severe disease, given the proper growth environment. On the other, some not so virulent bacteria can still produce disease, if the number of bacteria is sufficiently large, or if the host is compromised.Virulent bacteria have two important
mechanisms by which they can cause disease: invasiveness and production of toxins and enzymes.Invasiveness refers to the ability of pathogen to enter the body and spread
throughout the body. Two cellular structures help pathogens invade the host,s tissues: the pilus and the capsule.
The pilus allows some pathogens to adhere to certain types of tissues, even though the body,s secretions try to dislodge these pathogens for example Escherichia coli and neisseria gonorrhea use pili to attach to the surface of cells in the urinary tract. The capsule helps pathogens to resist engulfment by phagocytes in order to survive, therefore the bacteria with capsule are more virulent for example streptococcus pneumoniae, bacteroides fragilis.Invasiveness-ability of a pathogens to enter the body and spread throughout the tissues. Toxin-poison that can cause a disease or contribute to it. Exotoxins-extremely potent toxins excreted into the host by pathogens for example tetanus, diphtheria, botulinum, pseudomonas exotoxin. A-lethal for mammalian cells, enterotoxin produced by vibrio cholerae, exotoxins form staph.aureus responsible for toxic shock syndrome.Endotoxins-weaker than extotoxins.They are part of the cell wall of gram-negative bacteria and they affect the host when the cell wall breaks down. Enzymes-proteins that speed up or slow down the chemical reacions in the organism. some of them are toxic and contribute to the disease-producing potential
of pathogen.
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