PneumoPhageColor - development of a colorimetric biodetection kit for Pseudomonas aeruginosa based on phage particles

Abstract

Infectious diseases kill between 17-20 million people a year worldwide, and about 10 million people acquire hospital infections (HI) and, from this universe, almost 300,000 die. HIs increase both the length of permanence in the hospital and treatment costs, besides contributing significantly to the morbidity and mortality in hospitalized patients. In Brazil, the exact prevalence of HIs is still unknown, however, a national survey conducted by the Ministry of Health revealed, among several institutions evaluated, a rate of nosocomial infections ranging from 13% to 15%. The rate of HIs in Brazil presents high values and is considered almost the double when compared to other countries. Thus, hospital acquired infections represents a major challenge to be faced by the government and society for the implementation of prevention and control of infection in hospitals. Among the microorganisms that cause HIs one can highlight the multidrug-resistant Pseudomonas aeruginosa, which represents a major threat to patients in health care services. Data from 2007 points to P. aeruginosa as the most frequently isolated pathogen in patients with nosocomial pneumonia, a common cause of urinary tract infections, surgical wound and burn infections, being also present in bloodstream infections. The bacterium P. aeruginosa has been highlighted in the social media in Brazil about seven years ago, following the death of the 20 year-old model Mariana Bridi, on January 24th 2009, at Dorio Silva Hospital in the city of Serra (ES). According to a spokesperson of the state government, the death was due to complications from a generalized serious infection, originated from a urinary tract infection. In recent years, nosocomial infections caused by multiresistant Gram-negative microorganisms has increased consistently in Brazilian hospitals, and the bacterium P. aeruginosa was responsible for 10% of all nosocomial infections. It is intended that PneumoPhageColor will be a rapid detection (> 2 hours <5h) and low-cost kit for the high precision biodetection of P. aeruginosa, based on the use of a hydrogel sensitive to color changes, fixed on a support material, containing phage particles (or a cocktail of phage particles) specific and strictly lytic against P. aeruginosa. The proposed concept is not new, existing from about 3.5 billion years, having been initiated when bacteria and bacteriophages established a predator-prey balance. Bacteriophages are the most abundant organisms on our planet (are estimated at more than 10^31 particles) being completely safe for all organisms including humans, except for their target bacterial hosts. The idea embodied in PneumoPhageColor is unconventional and a highly creative approach, since it will join the solution (phage) with the problem (bacteria) in order to detect the latter. One intends to establish the proof-of-concept using a bacteriophage and a collection strain of P. aeruginosa. This research project will investigate the potential for the structural and functional stabilization of a lytic phage (or cocktail of lytic phage particles) with broad-spectrum, capable of infecting P. aeruginosa, within a hydrogel with chromogenic characteristics. Specific reagents will be incorporated into the optimized hydrogel in varying concentrations, in order to produce signal (color) if it is present in the gel a certain intracytoplasmic enzyme, released by phage lysis should bacterial cells of P. aeruginosa become into contact with the hydrogel. The intensity of the color produced in the hydrogel will give an idea of the bacterial load present, and this intensity will be measured by an optical sensor coupled to a signal transducer. (AU)