Restore antibiotic sensitivity in pandrug-resistant bacterial strains using phages.

Author: Luka Sanikidze
Keywords: Phages, MDR, PDR
Annotation:

On February 27, 2017, the World Health Organization published its first ever list of antibiotic-resistant "priority pathogens" – a catalogue of 12 families of bacteria that pose the greatest threat to human health. The list was drawn up in a bid to guide and promote research and development (R&D) of new antibiotics, as part of WHO’s efforts to address growing global resistance to antimicrobial medicines. The list highlights in particular the threat of gram-negative bacteria that are resistant to multiple antibiotics. These bacteria have built-in abilities to find new ways to resist treatment and can pass along genetic material that allows other bacteria to become drug-resistant as well. The WHO list is divided into three categories according to the urgency of need for new antibiotics: critical, high and medium priority. The most critical group of all includes multidrug resistant bacteria that pose a particular threat in hospitals, nursing homes, and among patients whose care requires devices such as ventilators and blood catheters. They include Acinetobacter, Pseudomonas and various Enterobacteriaceae (including Klebsiella, E. coli, Serratia, and Proteus). They can cause severe and often deadly infections such as bloodstream infections and pneumonia. These bacteria have become resistant to a large number of antibiotics, including carbapenems and third generation cephalosporins – the best available antibiotics for treating multi-drug resistant bacteria. Pseudomonas aeruginosa is a common encapsulated, Gram-negative, rod-shaped bacterium that can cause disease in plants and animals, including humans. A species of considerable medical importance, P. aeruginosa is a multidrug resistant pathogen recognized for its ubiquity, its intrinsically advanced antibiotic resistance mechanisms, and its association with serious illnesses – hospital-acquired infections such as ventilator-associated pneumonia and various sepsis syndromes. The organism is considered opportunistic insofar as serious infection often occurs during existing diseases or conditions – most notably cystic fibrosis and traumatic burns. It generally affects the immunocompromised but can also infect the immunocompetent as in hot tub folliculitis. Treatment of P. aeruginosa infections can be difficult due to its natural resistance to antibiotics. When more advanced antibiotic drug regimens are needed adverse effects may result. Pseudomonas aeruginosa leads to the risk of hospitalized nosocomial infections and 10% of worldwide nosocomial infections. Also, the leading role in urological diseases, purulent-surgical and etiology of infections caused by burns, besides the colonization of medical inventory and equipment. P. aeruginosa contains a number of factors that determine pathogenicity (synthesis of proteases, exotoxins etc.), which is used to disrupt the host body's defenses. The most important of these is the ability to produce biofilm, which makes it impossible for the immune response of antibiotics and the host body. In addition, P. aeruginosa is naturally resistant to antibiotics of many species and has the ability to develop more resistance, at the expense of gene horizontal transfer, which further complicates the treatment process. It is also known for its resistance againts the "Drug of last resort " as a "pan-drug-resistant" (PDR) bacteria. Due to this, the diseases caused by P. aeruginosa are not only common in comparison to other pathogens but are associated with high quality morbidity and mortality due to resistance. Because of antibiotic resistance and namely P. aeruginosa's multi-resistant strains are the biggest problem and challenge, it is important to find solutions for this problem. The most effective way against bacterial diseases is the combination of bacteriophages and antibiotics. In this case, I decided not to study the simultaneous effects of antibiotics and phages but to restore the sensitivity to the antibiotics, in P. aeruginosa, which is completely resistant using phages. The study was carried out at the R&D Department of George Eliava Institute of Bacteriophages, Microbiology and Virology. The object of the study was taken from the collection of Eliava R&D Department. Based on the interaction of antibiotics and bacteriophages from the 26 P.aeruginosa strains was selected one clinical strain (which was isolated in 2013 in Georgia)_ Ps 573 which was a PDR strain and was resistant to a combination of 15 different antibiotics. Using the screening test conducted on the strain shown that the phages from Eliava collection can eliminate P. aeruginosa PDR bacterial strain. The main goal of the research is to study the change in antibiotic sensitivity in the mutant strain resulting from induction of one of the phages (PT15) using gene expression.