Presence and clinical significance of bacterial DNA and other bacterial markers in culture-negative clinical samples from patients with severe liver pathologies

During the infectious process, pathogens may reach anatomical sites where they are exposed to substances hindering their growth. These substances, i.e. immunological molecules and antibiotics, cause the inhibition of bacterial growth and the infection is usually stopped. However, as observed in the environment, also in infected host suboptimal concentrations of inhibitory molecules and a number of stress conditions might induce the activation of survival mechanisms blocking the division capability of bacteria but allowing them to stay alive. The “dormant” bacteria can be re-activated in particular circumstances and might determine recurrent infections and some researchers have considered the possibility that “non-recoverable” microbial forms (wall-deprived bacteria, injured microorganisms, viable but nonculturable (VBNC) forms, dormant bacteria) may cause disease. The non-dividing or injured bacteria cannot be identified by standard diagnostic microbiological procedures based on culture methods. For this reason, in recent times the application of molecular methods to the microbiological diagnosis is increasing despite of the lack of a clear clinical significance of the obtained results.