Frequency of resistance to Staphyloccocus aureus-specific phages in mice

Value 1.3E-08 unitless Range: ±4.16E-09 unitless
Organism Bacteria Staphylococcus aureus
Reference Capparelli R, Parlato M, Borriello G, Salvatore P, Iannelli D. Experimental phage therapy against Staphylococcus aureus in mice. Antimicrob Agents Chemother. 2007 Aug51(8):2765-73. p.2771 right column 2nd paragraphPubMed ID17517843
Comments P.2771 right column 2nd paragraph: "Evolution of phage resistance. A concern often expressed about phage therapy is that bacteria can become refractory to phages. This study provides data relevant to this point. Different organs (spleen, kidneys, and heart) and the blood of more than 50 mice infected with S. aureus A170 and treated with phage MSa [a bacteriophage active against Staphylococcus aureus] concurrently (Fig. 4) or 10 days after infection (Fig. 7) were all found to be sterile when the animals were sacrificed at the end of the experiment. In vivo, phage-resistant staphylococci might be cleared rapidly by the immune system. The frequency of phage-resistant bacteria was therefore also measured in vitro. Five large bacterial cultures (10^8 CFU [colony-forming unit]/ml) in rich (LB) medium were infected with phage WSa (10^9 PFU [plaque-forming unit]/ml) and incubated at 37°C overnight. The observed frequency of phage-resistant bacteria was 1.3 × 10^−8 ± 4.16 × 10^−9. The above results confirm previous studies (refs 8, 11, 32) indicating that phage resistance is a rare event, perhaps rarer than antibiotic resistance (refs 11, 32). "
Entered by Uri M
ID 112570