- Smoking cigarettes may cause certain bacteria to build up in the mouth
- These bacteria fight against the body's immune system
- This then increases the risk of developing oral diseases
The mouth is one of the "dirtiest" parts of the body, home to millions of germs.
Smoking cigarettes can increase the likelihood that certain bacteria like Porphyromonas gingivalis will not only set up camp but will build a fortified city in the mouth and fight against the immune system, researchers said.
Scientists from University of Louisville in the US studied how cigarettes lead to colonisation of bacteria in the body.
They identified how tobacco smoke, composed of thousands of chemical components, is an environmental stressor and promotes bacteria colonisation and immune invasion.
Cigarette smoke and its components also promote biofilm formation by several other pathogens including Staphylococcus aureus, Streptococcus mutans, Klebsiella pneumonia and Pseudomonas aeruginosa, said David A Scott from Louisville.
Biofilms are composed of numerous microbial communities often made up of complex, interacting and co-existing multispecies structures. Bacteria can form biofilms on most surfaces including teeth, heart valves and the respiratory tract, researchers said.
"Once a pathogen establishes itself within a biofilm, it can be difficult to eradicate as biofilms provide a physical barrier against the host immune response, can be impermeable to antibiotics and act as a reservoir for persistent infection," said Scott.
"Furthermore, biofilms allow for the transfer of genetic material among the bacterial community and this can lead to antibiotic resistance and the propagation of other virulence factors that promote infection," he said.
One of the most prevalent biofilms is dental plaque, which can lead to gingivitis - a gum disease found in almost half the world's population - and to more severe oral diseases, such as chronic periodontitis, researchers including Juhi Bagaitkar, also from University of Louisville said.
Bacterial biofilms also can form on heart valves resulting in heart-related infections, and they also can cause a host of other problems, they said.
The findings were published in the journal Tobacco Induced Diseases.