Genome sequence of the broad-host-range Pseudomonas phage Phi-S1

The broad-host-range lytic Pseudomonas phage Φ-S1 possess a 40,192 bp double-stranded DNA (dsDNA) genome of 47 open reading frames (ORFs) and belongs to the family Podoviridae, subfamily Autographivirinae, genus T7likevirus.S.S. acknowledges the financial support from the Portuguese Foundation for Science and Technology (FCT) (grant SFRH/BPD/48803/2008) and the FCT project PTDC/EBB-BIO/114760/2009

The use of bacteriophages to control biofilms

Este resumo faz parte de: Book of abstracts of the Meeting of the Institute for Biotechnology and Bioengineering, 2, Braga, Portugal, 2010. A versão completa do livro de atas está disponível em: http://hdl.handle.net/1822/1096

Phage control of dual species biofilms of Pseudomonas fluorescens and Staphylococcus lentus

Despite the recent enthusiasm for using bacteriophages as bacterial control agents, there are only limited studies concerning phage interaction with their respective hosts residing in mixed biofilm consortia and especially in biofilms where the host species is a minor constituent. In the present work, a study was made of mono and dual species biofilms formed by Pseudomonas fluorescens (Gram-negative) and/or Staphylococcus lentus (Gram-positive) and their fate after infection with phages. The dual species biofilms consisted predominantly of S. lentus. The exposure of these biofilms to a cocktail containing both P. fluorescens and S. lentus phages effectively killed and removed the hosts from the substratum. Additionally, this cocktail approach also controlled the hosts released from the biofilms to the planktonic phase. The ability of phages to control a host population present in minority in the mixed species biofilm was also assessed. For this objective, the biofilms were challenged only with phage øIBB-PF7A, specific for P. fluorescens and the results obtained were to some extent unpredicted. First, øIBB-PF7A readily reached the target host and caused a significant population decrease. Secondly, and surprisingly, this phage was also capable of causing partial damage to the biofilms leading to the release of the non-susceptible host (S. lentus) from the dual species biofilms to the planktonic phase. The efficiency of phage treatment of biofilms was to some extent dependent on the number of cells present and also conditioned by the infection strategy (dynamic or static) utilized in the infection of the biofilms. Nevertheless, in most circumstances phages were well capable of controlling their target hosts.Fundação para a Ciência e a Tecnologia (FCT

Seeking a phage-based therapy to control otitis media

info:eu-repo/semantics/publishedVersio

Isolation and characterization of a T7-like lytic phage for Pseudomonas fluorescens

Background: Despite the proven relevance of Pseudomonas fluorescens as a spoilage microorganism in milk, fresh meats and refrigerated food products and the recognized potential of bacteriophages as sanitation agents, so far no phages specific for P. fluorescens isolates from dairy industry have been closely characterized in view of their lytic efficiency. Here we describe the isolation and characterization of a lytic phage capable to infect a variety of P. fluorescens strains isolated from Portuguese and United States dairy industries. Results: Several phages were isolated which showed a different host spectrum and efficiency of lysis. One of the phages, phage ϕIBB-PF7A, was studied in detail due to its efficient lysis of a wide spectrum of P. fluorescens strains and ribotypes. Phage ϕIBB-PF7A with a head diameter of about 63 nm and a tail size of about 13 × 8 nm belongs morphologically to the Podoviridae family and resembles a typical T7-like phage, as analyzed by transmission electron microscopy (TEM). The phage growth cycle with a detected latent period of 15 min, an eclipse period of 10 min, a burst size of 153 plaque forming units per infected cell, its genome size of approximately 42 kbp, and the size and N-terminal sequence of one of the protein bands, which gave similarity to the major capsid protein 10A, are consistent with this classification. Conclusion: The isolated T7-like phage, phage ϕIBB-PF7A, is fast and efficient in lysing different P. fluorescens strains and may be a good candidate to be used as a sanitation agent to control the prevalence of spoilage causing P. fluorescens strains in dairy and food related environments.Quebec, Canada; Portuguese Foundation for Science and Technology (FCT).Cornell University, N.Y., U.S.A.; Laval University

The use of bacteriophages for P. aeruginosa biofilm control

Pseudomonas aeruginosa is a relevant opportunistic pathogen frequently associated with several nosocomial infections and, worryingly, this bacterium shows a low antibiotic susceptibility. One of its virulence factors is related with the ability to adhere to surfaces and also human epithelium and form virulent biofllms. This work describes the isolation and characterization of lytic phages capable to infect antibiotic resistant P. aeruginosa strains. It is also described herein the potential of the new isolated phages for planktonic cells and biofilm control. According to the results of this work, the isolated phages showed different spectra of activity and most of them were efficient even against P. aeruginosa multidrug resistant strains. Furthermore, the biofilm infection assays revealed that phages can be a good strategy to combat virulent biofilms achieving significant reductions in the number of biofilm cells.(undefined

The use of bacteriophages against P. aeruginosa biofilms

P. aeruginosa is a relevant opportunistic pathogen involved in nosocomial infections and, worryingly, it frequently shows a low antibiotic susceptibility. One of its virulence factors is associated with the ability to adhere to surfaces and form virulent biofilms. This work describes the use of newly isolated broad host lytic phages (T7-like), capable to infect antibiotic resistant P. aeruginosa strains, to control planktonic and biofilm cells. Furthermore, it characterizes phage-resistant mutants phenotypes which arose after biofilm treatment with phages. Two of the phages used (phages phiIBB-PAA2 and phiIBB-PAP21) caused a great biomass reduction of planktonic cells, and when tested against 24 hours old biofilms, using a MOI of 1, reduced already after 2 hours of infection the amounts of viable cells by approximately 1 - 2 log and, this reduction was further enhanced after 6 hours of biofilm infection. However, P. aeruginosa PAO1, after 24 hours in contact with phiIBB-PAP21, acquired resistance to the phage which led to an increase in the amount of biofilm cells. Conversely, after 24 hours, phage phiIB-PAA2 for P. aeruginosa ATCC10145 continued to destroy cells. Based on morphological analysis of the colonies, five different P. aeruginosa phenotypes were isolated, after 72 hours of P. aeruginosa ATCC 10145 biofilm infection with phage phiIBB-PAA2, and only one remained susceptible to the phage. Furthermore, all phage-resistant phenotypes revealed a reduced ability to form biofilms resulting in lower amounts of biomass and viable cells in 24 hours old biofilms and, after 48 hours of biofilm formation, 3 out of these 5 strains continued to form less biofilm compared to the parental strain suggesting that these strains have an attenuated virulence. Overall, the phages used in this work showed a great capacity in infecting a wide number of antibiotic resistant strains and also control biofilms. Nevertheless, we found that phage-resistant phenotypes can arise quickly after exposure of biofilms to phages

Combined antibiotic-phage therapies to control Pseudomonas aeruginosa biofilms

Pseudomonas aeruginosa is responsible for 65% of mortality in hospitals all over the world. Its prevalence is attributed to factors such as: intrinsic resistance determined by virulence factors; acquired resistance mechanisms that lead to a low susceptibility to antimicrobial agents; and ability to attach to any natural and artificial surfaces and form biofilms. The emergence of new strategies to control P. aeruginosa biofilms is becoming more evident due to their tolerance to traditional treatments and bacteriophages have been recognized as an attractive alternative for this problem. Nevertheless, despite the potential of phages as antimicrobial agents, it is well known that bacteria can quickly adapt and create new survival strategies and the emergence of phage-resistant phenotypes is inevitable. Thus, the combination of phage and antibiotic therapies could have potentially more benefits than just using phages and antibiotics alone. This work describes the combinatory treatment using P. aeruginosa phages and antibiotics (amikacin, ciprofloxacin, piperacillin and tetracycline) against biofilms. The efficacy of phages and antibiotics were evaluated by the enumeration of viable cells and the determination of biofilm biomass. All antibiotics tested showed little efficacy against biofilms which were also very tolerant to phage infection, partially due to the fast emergence of resistant phenotypes with LPS mutations. However, the association of phage and ciprofloxacin caused a 100% biofilm removal. Synergy was observed with a combined phage-ciprofloxacin treatment, and overall an additive effect was seen with piperacillin and tetracyclin. Antagonism was observed with amikacin. Nevertheless, all antibiotic-phage combined treatments caused the disruption of the biofilm matrix. The effectiveness of combined treatments with phages and antibiotics can be due to several factors, namely high burst sizes in cells exposed to antibiotics (ex. piperacillin), lower MIC values and altered surface charges of phage resistant phenotypes and disruption of the biofilm matrix induced by some of the phages which can enhance the antibiotic penetration