Auricular prosthesis positioning using virtual planning in combination with additive manufacturing.

INTRODUCTION: This study focused on deformed or missing auricles and their replacement with silicone prostheses which are retained by craniofacial implants. Surgeons find it difficult to accurately place the implants in relation to the missing auricle in theatre. The aim of this study was to develop patient-specific devices using additive manufacturing technologies and associated software to indicate the positions of implants and to correctly orientate the prostheses relative to the positions of the implants. MATERIAL AND METHODS: The morphology of the patient was determined using Computed-Tomography (CT) scanning and the opposite auricle was mirrored in the virtual environment through specialized software from Materialise. A positioning guide for placing the implants was developed, together with an orientation guide that orientates the prosthesis accurately in relation to the implants. The orientation guide is a new development in the field of maxillofacial prosthetics and has not been attempted before. The guides are produced in nylon through laser sintering additive manufacturing. RESULTS: The accuracy of implant placements was determined and the results showed relatively accurate positioning using the guides. DISCUSSION: Implant placement showed some deviation which can largely be attributed to improper use of the guide by the surgeon during the marking of implant positions. The orientation guide can however somewhat compensate for this to still achieve aesthetically pleasing results. Using the guides significantly reduces risk, time and cost in placing the implants and producing auricular silicone prostheses.

Performance of a rapid phage-based test, FASTPlaqueTB, to diagnose pulmonary tuberculosis from sputum specimens in South Africa.

SETTING: Twelve primary health care clinics in the South Peninsula Administration, Cape Town, Western Cape Province, South Africa. OBJECTIVE: To evaluate the performance of FAST-PlaqueTB, a new phage-based test, for the rapid diagnosis of TB in individuals with no previous history of TB treatment presenting at primary health care clinics in Cape Town, South Africa. DESIGN: A comparative study of FASTPlaqueTB, auramine smear microscopy and Lowenstein-Jensen culture of 1692 decontaminated sputum specimens from 853 patients suspected of having TB. Resolution of discrepant results was undertaken by review of clinical information, chest X-ray and follow-up of treatment outcomes. RESULTS: FASTPlaqueTB detected TB in 75.2% of culture-confirmed cases and 70.3% of all cases with a clinical diagnosis of TB, with a specificity of 98.7% and 99.0%, respectively. The performance parameters of FASTPlaqueTB were significantly superior to those of concentrated auramine smear microscopy (63.4% and 61.3% sensitivity, and 97.4% and 97.3% specificity in culture-confirmed and all cases, respectively). Of those patients with two negative sputum smears, FAST-PlaqueTB detected TB in 54.1% of TB cases confirmed by culture and 48.8% of all cases with a clinical diagnosis of TB. A combination of smear microscopy and FASTPlaqueTB enabled 81.2% of culture-confirmed cases and 78.4% of total TB cases to be detected within 2 days of presentation. CONCLUSION: FASTPlaqueTBTM is a rapid, manual test for the diagnosis of TB. The test has significantly higher sensitivity overall compared with auramine sputum smear microscopy in individuals with no previous history of TB treatment, although smear microscopy did detect the most infectious of the TB cases. The FAST-PlaqueTB test is easy to perform, requires no dedicated equipment, and results are read by eye within 48 hours. This test can be useful for the diagnosis of TB in developing countries with a high burden of TB where other rapid diagnostic tests may not be appropriate. The test shows promising performance, particularly in the diagnosis of smear-negative disease, and could be used in conjunction with smear microscopy to aid in the diagnosis of additional cases of TB.

Evaluation of FASTPlaqueTB-RIF, a rapid, manual test for the determination of rifampicin resistance from Mycobacterium tuberculosis cultures.

SETTING: Two Mycobacteriology Reference Laboratories in Johannesburg (Laboratory 1) and Cape Town (Laboratory 2), South Africa. OBJECTIVE: To determine the ability of the FASTPlaqueTB-RIF test to correctly identify rifampicin susceptibility on strains of Mycobacterium tuberculosis cultured on solid media. DESIGN: A comparative study of FASTPlaqueTB-RIF and conventional drug susceptibility methods, with selection bias to include sufficient rifampicin resistant strains. RESULTS: Rifampicin susceptibility results were available for 191 strains of M. tuberculosis. Eighty-one strains were found to be rifampicin resistant and 110 strains were rifampicin susceptible by conventional methods. The sensitivity, specificity and overall accuracy for the FASTPlaqueTB-RIF were 100%, 97% and 98% at Laboratory 1, and 100%, 94% and 97% at Laboratory 2. CONCLUSION: FASTPlaqueTB-RIF offers a performance comparable to the gold standard proportion methods of rifampicin susceptibility testing, as well as the advantage of the speed of results that the newer methods deliver, without the need for specialised equipment. This makes FASTPlaqueTB-RIF a rapid test for rifampicin resistance suitable for widespread application.