Assessment of the effect of addition of 24 hours of oral tranexamic acid post-operatively to a single intraoperative intravenous dose of tranexamic acid on calculated blood loss following primary hip and knee arthroplasty (TRAC-24): a study protocol for a randomised controlled trial.

BACKGROUND: While it is has been proven that tranexamic acid (TXA) reduces blood loss in primary total hip and knee arthroplasty (THA and TKA), there is little published evidence on the use of TXA beyond 3 h post-operatively. Most blood loss occurs after wound closure and the primary aim of this study is to determine if the use of oral TXA post-operatively for up to 24 h will reduce calculated blood loss at 48 h beyond an intra-operative intravenous bolus alone following primary THA and TKA. To date, most TXA studies have excluded patients with a history of thromboembolic disease. METHODS/DESIGN: This is a phase IV, single-centred, open-label, parallel-group, randomised controlled trial. Participants are randomised to one of three groups: group 1, an intravenous (IV) bolus of TXA peri-operatively plus oral TXA post-operatively for 24 h; group 2, an IV bolus of TXA peri-operatively or group 3, standard care (no TXA). Eligible participants, including those with a history of thromboembolic disease, are allocated to these groups with a 2:2:1 allocation ratio. The primary outcome is the indirectly calculated blood loss 48 h after surgery. Researchers and patients are not blinded to the treatment; however, staff processing blood samples are. Originally 1166 participants were required to complete this study, 583 THA and 583 TKA. However, following an interim analysis after 100 THA and 100 TKA participants had been recruited to the study, the data monitoring ethics committee recommended stopping group 3 (standard care). DISCUSSION: TRAC-24 will help to determine whether an extended TXA dosing regimen can further reduce blood loss following primary THA and TKA. By including patients with a history of thromboembolic disease, this study will add to our understanding of the safety profile of TXA in this clinical situation. TRIAL REGISTRATION: ISRCTN registry, ISRCTN58790500 . Registered on 3 June 2016, EudraCT: 2015-002661-36.

CAMP factor homologues in Propionibacterium acnes: a new protein family differentially expressed by types I and II.

Analysis of the draft genome sequence of the opportunistic pathogen Propionibacterium acnes type strain NCTC 737 (=ATCC 6919) revealed five genes with sequence identity to the co-haemolytic Christie-Atkins-Munch-Peterson (CAMP) factor of Streptococcus agalactiae. The predicted molecular masses for the expressed proteins ranged from 28 to 30 kDa. The genes were present in each of the three recently identified recA-based phylogenetic groupings of P. acnes (IA, IB and II), as assessed by PCR amplification. Conserved differences in CAMP factor gene sequences between these three groups were also consistent with their previous phylogenetic designations. All type IA, IB and II isolates were positive for the co-haemolytic reaction on sheep blood agar. Immunoblotting and silver staining of SDS-PAGE gels, however, revealed differential protein expression of CAMP factors amongst the different groups. Type IB and II isolates produced an abundance of CAMP factor 1, detectable by specific antibody labelling and silver staining of SDS-PAGE gels. In contrast, abundant CAMP factor production was lacking in type IA isolates, although larger amounts of CAMP factor 2 were detectable by immunoblotting compared with type II isolates. While the potential role of the abundant CAMP factor 1 in host colonization or virulence remains to be determined, it should be noted that the type strain of P. acnes used in much of the published literature is a type IA isolate and is, therefore, lacking in this attribute.