biology question #1418



C. Davies, a 38 year old female from Knoxville asks on May 1, 2003,

Q:

If a person has a bacterial infection and sneezes on a piece of paper, how long will the bacteria live? And the lifespans and names other types of bacteria or virus germs that could live on the paper.

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the answer

Wendy Hutchins answered on July 7, 2003, A:

Different species and strains of bacteria have different life spans - or more acurately, times for which they would remain viable in an unfavourable environment. Certainly what one bacteria would like, another would not. Most of the bacteria that cause human infections like body temperature (close to 37oC). Some of those are resistant to relatively cold temperatures and drying, such as being on a piece of paper at room temperature. Many of the viruses certainly can survive the trip to the surface. A full list of viruses, bacteria and fungi that can cause respiratory infections AND survive on a piece of paper would be very long indeed. Some more well known examples are: Pseudomonas aeruginosa that causes pneumonia in people with cystic fibrosis. It is more commonly found in mountain streams and in your tap water. All of the organisms that are found in water would survive on a surface like paper too. Most of these are not truly pathogenic (cause disease) except in people with other problems like cystic fibrosis (called opportunists - they cause infection when your immune system is not functioning). The common cold virus is a good viral example of a surface survivor. Many of the other bacteria and viruses that cause pneumonia or sinusitis or other respiratory diseases pefer the warm 37oC environment, so they won't last as long as the water-borne organisms on the paper. Haemophilus influenzae is an example of a bacterial species that likes it warm and moist rather than cold and dry. There are many bacteria that normally live in our respiratory tract that are also able to survive on the paper because their temperature range is broad enough. Staphylococcus and Streptococcus are like that. Both are also found on your skin where it is much cooler. Just to make bacterial life interesting, there are bacteria that not only would survive on the paper, but are able to digest the paper as a food source. These bacteria are environmental and make a living digesting plant material on the ground. Needless to say, these bacteria don't like our hot 37oC bodies, so we wouldn't ever catch a disease from them.

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