Intraperitoneal polyphosphate prevents mortality from bacterial peritonitis

Author(s):
Jack Archer; Rebecca Meltzer; Alexander Zaborin; Olga Zaborina; Sanjiv Hyoju; John Alverdy

Background:

Our lab seeks to prevent infection by exploring non-antibiotic, anti-virulence agents that promote bacterial growth while suppressing bacterial virulence. This “econeutral” approach may limit the use of antibiotics and hence antibiotic resistance.

Hypothesis:

Here we hypothesized that local intraperitoneal (IP) co-administration of an FDA approved 3-mer of phosphate, tripolyphosphate (PPi-3), can prevent mortality following systemic (intraperitoneal-IP) inoculation of Pseudomonas aeruginosa or Serratia marcescens. The aims of this study were to demonstrate the in vitro virulence suppression activity of PPi-3 and determine its in vivo effect on mortality in mice following IP administration of Pseudomonas aeruginosa or Serratia marcescens.

Methods:

First, we determined the in vitro effect of PPi-3 on P. aeruginosa and S. marcescens by examining their growth characteristics and virulence expression as judged by hemolysis and biofilm production. Next, we determined the in vivo effect of PPi-3 to prevent mortality in mice following IP inoculation of P. aeruginosa and S. marcescens by comparing IP PPi-3 to normal saline. Mice were followed for mortality, sacrificed and blood, peritoneal fluid, liver, and spleen were obtained for culture.

Results:

While the addition of PPi-3 to P. aeruginosa growth media in vitro had a negligible effect on bacterial growth (0.5 ± 0.1 vs. 0.6 ± 0.01, P = 0.1); it significantly decreased the production of hemolysin (1.3 ± 0.03 vs 3.3 ± 0.02 P < 0.0001) and biofilm (0.13 ± 0.02 vs 0.29 ± 0.003 P < 0.05).  PPi-3 significantly, yet minimally, suppressed the growth of S. marcescens (PPi-3 0.9 ± 0.01 vs normal saline 1.2 ± 0.02  P< 0.001) and suppressed biofilm formation (PPi-3 0.25 ± 0.03 vs normal saline 0.42 ± 0.01 P<0.001)  In vivo, contemporaneous IP PPi-3 prevented mortality from IP P. aeruginosa (0%-PPi-3 vs. 80%-saline) (n=20/group P<0.0001) and S. marcescens (40%- PPi-3 vs. 80%-saline) (n=20/group P < 0.01). Cultures demonstrated pathogen clearance in association with survival (data not shown).

Conclusions:

IP application of PPi-3 versus normal saline was efficacious at decreasing mortality from pathogens commonly encountered in patients with peritonitis perhaps via its in vitro effect on bacterial virulence. Further work is underway to elucidate these mechanisms.