Methods for purifying bacteriophage and products of manufacture containing endotoxin-free bacteriophage preparations

A method for purifying bacteriophage (phage) and generating a substantially endotoxin free preparation of phage, comprising:

• (a) providing a sample comprising a bacteriophage (phage), wherein optionally the phage propagated are added during mid-log stage of bacterial growth, and
• (b) filtering, or ultrafiltering, the sample with a dead-end microfiltration and a pressure-driven cross-flow ultrafiltration (CFF) comprising a molecular weight cut-off (MWCO) at about 100 kDa, optionally filtering with dead-end microfiltration and cross-flow ultrafiltration (CFF), optionally filtering or ultrafiltering as illustrated in FIG. 3 or FIG. 8, wherein a membrane pore size of about 100 kDa provides the ability to filter out an equivalent to a spherical particle with an about 3 nm diameter, thereby having the ability to retain substantially most phages,
• wherein any material smaller than a cross-flow membrane pore passes through the membrane, while larger phage particles remain in the retentate stream, and the CFF with an about 100 kDa membrane pore size removes both free endotoxin, which are approximately 10 kDa in size, and all known exotoxins, which are typically smaller than about 30 kDa, and a membrane pore size of about 100 kDa provides an equivalent to a spherical particle with a 3 nm diameter and can retain substantially most phages,
• thereby generating a substantially endotoxin free preparation of phage.