Persistent bacterial infection

Persistent infections are a global challenge for human being. The development of persistent infections has been exemplified as a game of "Cat and Mouse" in which the host tries to eliminate a pathogen while the pathogen tries to survive in the host. One common survival strategy employed by bacterial pathogens is to form biofilm, an amorphous and dynamic structure that is not only resistant to antibiotics, but also resistant to host immune clearance. Another survival strategy of bacterial pathogens is a resistance to antibiotics which is usually used in acute and chronic infectious conditions. Methicillin resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa are well-known bacterial pathogens for their antibiotics-resistance. MRSA displays resistance to methicillin, oxacillin, semisynthetic penicillin, β-lactam antibiotics such as cephalosporin and carbapenem. MRSA also displays resistance to macrolide, clindamycin, aminoglycoside and other commonly-used antibiotics. Compared to methicillin-sensitive S. aureus (MSSA) infections, treatment of MRSA infections requires more time and exacts higher costs, and produces higher mortality. Pseudomonas aeruginosa (PA) is ubiquitous in the natural environment and is widespread in hospitals, especially in humid environments. PA infection can be hard to treat because of its resistance to antibiotics. PA has not only inherent resistance but can also simultaneously acquire resistance to various antibiotics. Nearly all enzymatic and mutationally-acquired mechanisms of antibiotic resistance can be found in PA. The result can be a multi-drug resistant organism. Several pathogenic bacteria can induce persistent infection in the human body. Pathogenic bacteria such as Mycobacterium tuberculosis, Helicobacter pylori, and Salmonella enterica serova Typhi induce disease at an early stage before an adaptive host immune system response. Also, if these bacteria are not eradicated from the host, they can persist in protective niches. Theses pathogenic bacteria can survive from the host immune response and produce persistent infection and disease symptoms even though the host immune response is intact. With several genetic plasticities, they can inhibit the function of macrophage in granuloma, decrease surface antigenic presentation which can induce host's immune response, and grow intracellularly during specific period of infection. All these processes can cause persistent bacterial infection under intact host's immune system. In this article, we discuss about persistent bacterial infections and their mechanisms. Also we discuss the known therapeutic modalities of persistent infections. But the answer mentioned in this article would not be enough to solve the whole problems. We think it could be helpful to understand the exact mechanisms of persistent bacterial infections and also play some role to find solutions about persistent bacterial infections.