Infectious diseases caused by weak pathogenic bacteria

Abstract

Most of oral infectious diseases that we, dental scientists, study are due to bacteria indigenous to the oral cavity or other weak pathogenic bacteria. Recently, most of infectious diseases are due to weak pathogenic bacteria, for example, Staphylococcus aureus (involved methicillin-resistant Staphylococcus aureus, MRSA), Legionella, Serratia, vancomycin-resistant Enterococcus (VRE). The first feature of diseases infected with weak pathogenic bacteria is the opportunistic infection, because these are weak pathogens. Secondly, it is difficult to determine caused bacteria. Thirdly, in the hospital infection, to acquire the resistance to antibiotics contribute to pathogenicity. While strong pathogenic bacteria shows pathogenicity by exotoxins, weak pathogenic bacteria has a complex mechanism, which is not able to explain by a virulence factor, but by multi factors. In oral infectious diseases, dental caries, periodontal diseases are major, and most of them are caused by Streptococcus mutans and Porphyromonas gingivalis. And from the other oral infectious diseases, Prevotella intermedia/nigrescens were frequently isolated. These have various virulence factors, for example in relation to entry, attachment, evasion of host defense, cause damage to host cells, spread, and these contribute to diseases.In contemporary, compromised hosts have increased and environment is very hygienic, so infectious diseases of weak pathogens are not despised.