Bacteriophage-antibiotic synergism to control planktonic and biofilm producing clinical isolates of Pseudomonas aeruginosa

Abstract

Introduction: Pseudomonas aeruginosa (P. aeruginosa) is a highly resistant opportunistic pathogen and is capable of forming biofilms on medical devices. Bacterial biofilms, which are micro-colonies encased in extracellular polysaccharide material are so difficult to be treated by conventional antibiotics. During the last decade, P. aeruginosa phages have been extensively examined as an alternative to antimicrobial agents. The aim of the study was to assess bacteriophageantibiotic combination on planktonic and biofilm states of P. aeruginosa isolates. Materials: In this study, we isolated 6 lytic phages, from hospital effluents, they were tested against 50 P. aeruginosa strains, isolated from different clinical specimens delivered to the Diagnostic Microbiology Laboratories, Faculty of Medicine, Alexandria University. Results: Out of the 50 isolates, 15 were susceptible to these phages. So the biofilm forming capacity of these 15 isolates was investigated. The results showed that 14 isolates (93.33%) produced detectable biofilm. The minimum inhibitory concentration (MIC) and minimum biofilm eradication concentration (MBEC) assays were used to evaluate the antibiotic sensitivity patterns of these P. aeruginosa isolates in their planktonic and biofilm phases to amikacin and meropenem. Also, the effects of phage on the planktonic and biofilm states of isolates at different multiplicities of infections (MOI) were tested. On the planktonic state, the amikacin-phage combination showed synergistic effect (P = 0.001), and the meropenem-phage combination showed synergistic effect (P = 0.003). On the biofilm state, the amikacin-phage combination showed biofilm eradication Please cite this article in press as: Nouraldin AAM et al. Bacteriophage-antibiotic synergism to control planktonic and biofilm producing clinical isolates of Pseudomonas aeruginosa, Alex J Med (2015), http://dx.doi.org/10.1016/j.ajme.2015.05.002in 50% of the isolates (P = 0.003). On the other hand, the meropenem-phage combination showed biofilm eradication in 14.3% of the strains. Conclusion: The combination of phage and antibiotics could have potentially more benefits on P. aeruginosa planktonic and biofilm states than just using phages or antibiotics alone.

Development and Use of Personalized Bacteriophage-Based Therapeutic Cocktails To Treat a Patient with a Disseminated Resistant Acinetobacter baumannii Infection

“…The specificity of antibacteriophage systems makes it unlikely that broad anti-bacteriophage mechanisms will arise, as opposed to the spread of multidrug-resistant efflux pump mechanisms in response to conventional broad-spectrum antibiotic therapy. Finally, other reported benefits of bacteriophage therapy include an ability to exhibit synergy with or restore susceptibility to conventional antimicrobial agents, as observed in this case, and the potential ability to disrupt biofilms (24,25).…”

“…To evaluate the killing efficacy of each phage on clinical isolates, a dilution series of bacteriophage preparation was spotted on a bacterial lawn to observe plaque formation (25). Briefly, 100 l of an overnight culture of each A. baumannii isolate was used to individually inoculate 2.5 ml of 0.7% molten top agar (temperature, 50°C).…”

Rapid evolution of generalized resistance mechanisms can constrain the efficacy of phage–antibiotic treatments

“…So far, it has been reported that treating Klebsiella pneumoniae infections with a combination of phage and antibiotic is more successful at limiting the emergence of phage‐resistant pathogen mutants compared to antibiotic alone, even though no difference was observed in the effectiveness to eradicate biofilms (Verma, Harjai, & Chhibber, 2009). Another study found that phage–antibiotic combinations were more efficient at eradicating the planktonic and biofilm populations of multiple P. aeruginosa strains compared to antibiotic‐alone treatments, but the evolution of resistance was not measured in this study (Nouraldin, Baddour, Harfoush, & Essa, 2016). Of late, it was shown that phage–antibiotic combinations can considerably vary in their efficiency to eradicate P. aeruginosa biofilms depending on the specific phage species and the class of antibiotic (Chaudhry et al., 2017).…”

“…To explore the defensive function of biofilms in detail, we found that biofilm populations had higher levels of resistance compared to planktonic populations when exposed top selection by phage or antibiotic independently. Aminoglycoside antibiotics, including gentamycin, has been found to be less effective against biofilm than planktonic bacteria, largely due to decreased diffusion of antimicrobial agents through the biofilm matrix (Brockhurst, Buckling, & Rainey, 2006; Nouraldin et al., 2016). We found that control biofilm populations did not show clear resistance to phage or antibiotic.…”

Isolation and Characterization of a Lytic Bacteriophage (vB_PmiS-TH) and Its Application in Combination with Ampicillin against Planktonic and Biofilm Forms of Proteus mirabilis Isolated from Urinary Tract Infection

“…Bedi et al [2009] reported that a high concentration of an antibiotic with a phage significantly reduces the bacterial load of biofilm when compared to a phage or an antibiotic alone. The higher resistance of biofilm to ampicillin compared to the planktonic state of P. mirabilis could be attributed to decreased antibiotic diffusion through the extensive biofilm matrix, where there is an increase in alginate synthesis [Nouraldin et al, 2016]. Nevertheless, phages can attach to specific receptors, penetrate, and cause biofilm disruption and cell lysis.…”