Abstract :
There are a large number of diverse interactions between bacteria and their hosts. They range from a symbiotic relationship -beneficial for both parts- to an infection rapidly leading to the host’s death. Amidst these extremes lie the chronic infections. Disease is the manifestation of a combination of bacterial virulence factors and the host’s immune response. A number of bacterial species that produce chronic infectious diseases, such as P. aeruginosa, S. aureus, S. epidermidis or E.coli, are also capable of generating invasive acute infections. A clear example is P. aeruginosa, whose bacteraemia leads to death within hours if no treatment is provided. Such bacterium is able to persist for decades at high numbers [108 to 1010 colony forming units (CFU)/mL] in the airways of patients suffering from cystic fibrosis, never causing an invasive infection, or they can spread beyond the lungs.
As in other chronic infections, bacteria adapt to their environment. Growing evidence indicates biofilms play a major role in these adaptations. Bacteria exist in a biofilm state increase the bacterial resistance to antibiotics (because some characteristics of the structure and metabolic different state of the bacteria forming the biofilm are present) while shielding them from the immune system by masking antigens.
Keyword :
Transcranial Doppler ultrasound; Cerebral blood flow; Breath-holding vasoreactivity