A diagnostic evaluation of a molecular assay used for testing and treating anorectal chlamydia and gonorrhoea infections at the point-of-care in Papua New Guinea

OBJECTIVES

Papua New Guinea has among the highest prevalences of sexually transmissible infections (STIs) globally with no services able to accurately test for anorectal Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) infections. Here we prospectively evaluated the diagnostic performance of a molecular CT/NG assay used at the point-of-care (POC) with the aim of enhancing anorectal STI screening and same-day treatment.

METHODS

Men who have sex with men, transgender women and female sex workers taking part in Papua New Guinea's first large-scale biobehavioural study were enrolled and asked to provide a self-collected anorectal swab for POC GeneXpert CT/NG testing. Same-day treatment was offered if positive. A convenience sample of 396 unique and randomly selected samples were transported to Australia for comparison using the Cobas 4800 CT/NG test (Roche Molecular Diagnostics, Pleasanton, CA, USA).

RESULTS

A total of 326 samples provided valid results by Cobas whereas 70 samples provided invalid results suggesting inhibition. The positive, negative and overall percentage agreements of GeneXpert CT/NG for the detection of C. trachomatis were 96.7% (95% CI 92.3%-98.9%), 95.5% (95% CI 91.3%-98.0%) and 96.0% (95% CI 93.3%-97.8%), and for N. gonorrhoeae were 93.0% (95% CI 86.1%-97.1%), 100.0% (95% CI 98.3%-100.0%) and 97.8% (95% CI 95.6%-99.1%), respectively.

CONCLUSIONS

The overall rate of agreement between the GeneXpert and Cobas CT/NG assays was high with 96.0% for C. trachomatis and 97.8% for N. gonorrhoeae. Results from this study data suggest that the GeneXpert CT/NG assay is suitable for testing self-collected anorectal specimens at the POC and that same-day treatment was feasible.

Rodent animal models of delayed bone healing and non-union formation: a comprehensive review

Despite the growing knowledge on the mechanisms of fracture healing, delayed healing and non-union formation remain a major clinical challenge. Animal models are needed to study the complex process of normal and impaired fracture healing and to develop new therapeutic strategies. Whereas in the past mainly large animals have been used to study normal and impaired fracture healing, nowadays rodent models are of increasing interest. New osteosynthesis techniques for rat and mice have been developed during the last years, which allowed for the first time stable osteosynthesis in these animals comparable to the standards in large animals and humans. Based on these new implants, different models in rat and mice have been established to study delayed healing and non-union formation. Although in humans the terms delayed union and non-union are well defined, in rodents definitions are lacking. However, especially in scientific studies clear definitions are necessary to develop a uniform scientific language and allow comparison of the results between different studies. In this consensus report, we define the basic terms "union", "delayed healing" and "non-union" in rodent animal models. Based on a review of the literature and our own experience, we further provide an overview on available models of delayed healing and non-union formation in rats and mice. We further summarise the value of different approaches to study normal and delayed fracture healing as well as non-union formation, and discuss different methods of data evaluation.

Small animal bone healing models: standards, tips, and pitfalls results of a consensus meeting

Small animal fracture models have gained increasing interest in fracture healing studies. To achieve standardized and defined study conditions, various variables must be carefully controlled when designing fracture healing experiments in mice or rats. The strain, age and sex of the animals may influence the process of fracture healing. Furthermore, the choice of the fracture fixation technique depends on the questions addressed, whereby intra- and extramedullary implants as well as open and closed surgical approaches may be considered. During the last few years, a variety of different, highly sophisticated implants for fracture fixation in small animals have been developed. Rigid fixation with locking plates or external fixators results in predominantly intramembranous healing in both mice and rats. Locking plates, external fixators, intramedullary screws, the locking nail and the pin-clip device allow different degrees of stability resulting in various amounts of endochondral and intramembranous healing. The use of common pins that do not provide rotational and axial stability during fracture stabilization should be discouraged in the future. Analyses should include at least biomechanical and histological evaluations, even if the focus of the study is directed towards the elucidation of molecular mechanisms of fracture healing using the largely available spectrum of antibodies and gene-targeted animals to study molecular mechanisms of fracture healing. This review discusses distinct requirements for the experimental setups as well as the advantages and pitfalls of the different fixation techniques in rats and mice.

Local BMP-2 application can rescue the delayed osteotomy healing in a rat model

Delayed healing is still a severe complication in the clinic. The aim of the present study was to investigate the effect of locally delivered BMP-2 incorporated in a poly(d,l-lactide) (PDLLA) implant coating in a rat model with delayed tibial healing. The healing delay in this model is not caused by mechanical instability or additional tissue manipulation and presents therefore a common and challenging clinical situation of impaired healing. Radiological, histological and biomechanical evaluations were performed at days 5, 10, 28, 42, and 84 after tibial osteotomy. The control group showed a delayed healing without complete bridging and without reaching the biomechanical stability of the contralateral tibiae after 84 days. The mechanical stability of the BMP-treated tibiae showed a significant increase at days 28 and 42 compared to the control group and exceeded the stability of the intact contralateral tibiae. Less cartilage was detected at day 28 and the mineralisation was significantly enhanced at day 42 due to the local BMP application. Looking at the early healing phase (day 10) a reduced vascularisation was seen in the BMP group. This reflects the situation seen during normal healing, whereas the delayed healing in the present model had an increased vascularisation. The present study clearly demonstrates that local BMP-2 application can stimulate delayed healing in a clinically relevant animal model.