Question

The Ability to Adhere to Host Cells and Resist Physical Removal

Pseudomonas aeruginosa, a common cause of serious respiratory infections on people with cystic fibrosis, produces a single polar flagellum, can secrete a polysaccharide slime composed of alginate, and is able to produce both pili and cell wall adhesins.

How could each of these factors contribute to the bacterium's pathogenosis and in what order might they be used?

The Ability to Invade Host Cells

Bacteria such as Salmonella, and Shigella routinely enter intestinal epithelial cells.

State 2 advantages this might provide the bacterium in terms of its pathogenicity.

Answer 1

Bacteria are the causes of a number of diseases. Most of them are deadly. The structure of a typical bacteria consists of the following:

capsule

cell envelope

cell wall

cytoplasm

cytoplasmic membrane

flagella

nucleoid

pilli

ribosomes

The movement of bacteria is caused by flagella. This is a whip-lash like structure which may be one as in a few species or many. If one flagellum is present, it is located at one pole.This structure beats like the ore of a boat and produces movement of the organism towards light, away from toxins etc.

Besides, bacteria also possess a capsule which prevents from drying and thus helps the organism to survive.

Pilli are hairlike projections that emerge from outside cell surface.These structures help the bacteria to attach to other cell surfaces. without pilli the infective capacity of a bacteria is lost because the attachment capacity is not there. Pilli are also used in conjugation during which genetic materials are interchanged.

The slime layer surrounds the bacterial cells. This layer protects the bacteria from getting dehydrated and also protects from certain toxins.Slime layer also helps for attachment to other surfaces and in some cases protect the organism from sterilisation process as well.

cell wall adhesins are factors which allow attachments to the host cells( concept of adhesive).After attachment, the bacteria can penetrate the host cell to enter into the system. Reproduction of the species starts after it enters.

Thus flagella is used to move i.e. swim, pilli is used to attach to the suface of the host cell, adhesins help in attachment.

Slime layer is protective in function and protects the organism from the toxic effects of host chemicals. Thus if the introduction to the host cell and subsequent survival becomes possible, the bacteria can multiply and cause diseases in the host. Besides, the protective slimy layer and adhesins help in perfect attachment so that the organism can continue its life cycle without any danger.Respiration is also anaerobic i.e. in the absence of oxygen.