Natural and synthetic chemicals acting as enhancers of bacterial pathogenic success within the human host.

Like any other organism, bacteria are endowed with a myriad of receptors and signaling/regulatory mechanisms to detect chemical stimuli and develop appropriate responses. Whereas several of these chemicals - produced by bacteria themselves - display well-known effects in modulating their virulence-related performance (i.e. quorum sensing signals), many other substances not of microbial but different origin show an ability to influence bacterial behavior. The human organism poses the niche where pathogenic bacteria encounter some of these chemicals, since they are either produced naturally in the body (e.g. hormones, neurotransmitters, etc.) or are synthetic drugs/pollutants (sometimes called xenobiotics) to which people are frequently exposed at relevant doses mostly through inhalation or the diet. Alarmingly, several of these substances display effects that promote bacterial virulence, potentially having obvious negative consequences for the patient. In this scenario, this review integrates and discusses the most notorious data as to how different endogenous and synthetic compounds may impact bacteria biology within the human body context, finally improving their pathogenic success. Delving into this field is needed in order to emphasize the existence of chemicals to which exposure should be avoided as much as possible, and of some host/pathogen pathways that could be targeted so as to curb bacterial pathogenic power and thus alleviate the severity of certain infections.