Thread: Contagious Bacteria

I've been reading some stuff for school, and I have to answer questions. There's a question that asks "What makes some bacteria contagious?" I've looked up like 12 different sites, but they just give me information that I'll probably need if I was writing an essay about it.

I've read some of the stuff that people posted here and most of the time, people give back helpful information from their own knowledge. Can anyone help me with this subject?

Could you clarify what you mean by contagious?

If you're asking why some bacteria spread better than others, then you're asking about infectivity.

If you want to know what makes some bacteria more likely to cause harm to people, then you are asking about virulence. I suspect this is the one you're more interested in.

From wiki, here is a list of bacterial virulence factors.

Adhesion. Many bacteria must first bind to host cell surfaces. Many bacterial and host molecules that are involved in the adhesion of bacteria to host cells have been identified. Often, the host cell receptors for bacteria are essential proteins for other functions.
Colonization. Some virulent bacteria produce special proteins that allow them to colonize parts of the host body. Helicobacter pylori is able to survive in the acidic environment of the human stomach by producing the enzyme urease. Colonization of the stomach lining by this bacterium can lead to Gastric ulcer and cancer. The virulence of various strains of Helicobacter pylori tends to corellate with the level of production of urease.
Invasion. Some virulent bacteria produce proteins that either disrupt host cell membranes or stimulate endocytosis into host cells. These virulence factors allow the bacteria to enter host cells and facilitate entry into the body across epithelial tissue layers at the body surface.
Immune response inhibitors. Many bacteria produce virulence factors that inhibit the host's immune system defenses. For example, a common bacterial strategy is to produce proteins that bind host antibodies. The polysaccharide capsule of Streptococcus pneumoniae inhibits phagocytosis of the bacterium by host immune cells.
Toxins. Many virulence factors are proteins made by bacteria that poison host cells and cause tissue damage. For example, there are many food poisoning toxins produced by bacteria that can contaminate human foods. Some of these can remain in "spoiled" food even after cooking and cause illness when the contaminated food is consumed. Some bacterial toxins are chemically altered and inactivated by the heat of cooking.

I think when I meant by contagious, I think I mean like when they TURN contagious. I'm guessing they're saying that bacteria at a certain state cannot be contagious, so they're asking what makes some bacteria contagious as in harming others.

Most disease causing bacteria would be considered contagious at all times, are you maybe asking about how some normally passive bacteria can suddenly cause an infection.

In cases where natural flora turn bad, it is usually caused by a disruption of the flora, either from an intense change in the presence of a certain nutrient, (Like high iron in the blood of diabetics on insulin injectibles), or a physical disruption like douching causing vaginal infections. Also, many normally harmless bacteria can be deadly to an immune compromised individual. Although, fungi are the usual opportunistic pathogens that take advantage of situations like this, though some bacteria are known to do it as well.

Also, many bacteria are kept at bay quite effectively by your skin, S. aureus, is a good example of this. They normally don't harm you, but can cause some nasty infections if you get a bad cut and they get into more susceptible tissues.

Another possibility is that a bacteria could aquire virulence genes from mutation or sexual reprodution, and then could potentially become pathogenic.

This is exactly what I needed. Thank you for the information. I just wonder why the hell other websites don't tell me stuff straight foward like this.