An outlook on coronavirus disease 2019 detection methods / 药物分析学报

Diagnostic testing plays a fundamental role in the mitigation and containment of coronavirus disease 2019(COVID-19),as it enables immediate quarantine of those who are infected and contagious and is essential for the epidemiological characterization of the virus and estimating the number of infected cases worldwide.Confirmation of viral infections,such as COVID-19,can be achieved through two general approaches:nucleic acid amplification tests(NAATs)or molecular tests,and serological or antibody-based tests.The genetic material of the pathogen is detected in NAAT,and in serological tests,host antibodies produced in response to the pathogen are identified.Other methods of diagnosing COVID-19 include radiological imaging of the lungs and in vitro detection of viral antigens.This review covers different approaches available to diagnosing COVID-19 by outlining their advantages and short-comings,as well as appropriate indications for more accurate testing.

The use of NAAT- PCR to determine asymptomatic chlamydia and gonorrhoea infections in infertile patients undergoing hysterosalpingogram at the federal medical centre, Yenagoa, South-South Nigeria

Background: The roles of Chlamydia trachomatis and Neisseria gonorrhoeae in the aetiology of infertility due to tubal occlusion have been established by various studies. These organisms may lead to pelvic infection by ascending into the upper genital tract through any instrumentation like hysterosalpingography. The objectives were to determine the prevalence of asymptomatic chlamydial and gonorrhoeal infections of the genital tract among women being investigated for infertility referred for hysterosalpingography; the relationship of these infections with tubal pathologies; and if routine endo-cervical screening and prophylactic antibiotics be recommended for these patients.Methods: This was a descriptive cross-sectional study. The study population consisted of consecutive 220 infertile women that met the inclusion criteria for this study. Consent was obtained. Endo-cervical swab was taken for NAAT-PCR for Chlamydia trachomatis and Neisseria gonorrhoeae. Hysterosalpingography was carried out. Data was analyzed using SPSS (version 22).Results: Amongst the 220 women, 9 (4.1%) had asymptomatic chlamydia infection. None had gonorrhoea infection and 211 (95.9%) had none of these two organisms. Forty-eight (21.9%) of the 220 women had bilateral tubal blockage and 9 (18.8%) out of these 48 women had asymptomatic infection with Chlamydia trachomatis.Conclusions: There is a statistically significant association between tubal blockage and chlamydia infection (p = 0.00) [RR 4.31 (3.37-5.50)]. There was no evidence to recommend routine screening/antibiotics considering the low prevalence of microbes and the absence of post-HSG pelvic infection. Results from a multicenter randomized controlled trial will be more representative.

Gonorrhoea diagnostics: An update.

Diagnosis of gonorrhoea is an ongoing challenge. The organism is fastidious requiring meticulous collection and transport for successful cultivation. Asymptomatic infections are common which go undetected by conventional methods thereby leading to continued transmission and the risk of complications. The nucleic acid amplification tests, now increasingly used in developed countries, offer improved sensitivity compared to bacterial culture. However, these continue to suffer sequence related problems leading to false positive and false negative results. Further, these cannot be used for generation of data on antibiotic susceptibility because genetic markers of antibiotic resistance to recommended therapies have not been fully characterised. They are unaffordable in a setting like ours where reliance is placed on syndromic approach for sexually transmitted infection (STI) management. The use of syndromic approach has resulted in a considerable decline in the number of Neisseria gonorrhoeae isolates that have been cultured for diagnostic purposes. Many laboratories formerly doing so are no longer performing culture for gonococci, and the basic skills have been lost. There is a need to not only revive this skill but also adopt newer technologies that can aid in accurate diagnosis in a cost-effective manner. There is room for innovation that can facilitate the development of a point-of-care test for this bacterial STI.

Enhancing tuberculosis diagnosis by polymerase chain reaction: an experience at a tertiary hospital

Introduction: Tuberculosis (TB) persists as a severe global public health issue. The aim of the present study was to evaluate the performance of an in-house TB PCR (polymerase chain reaction) in sputum. Methods: DNA from sputum specimens were submitted to a nested-PCR protocol for the IS6110 region detection. PCR results were compared to those of the traditional methods for TB diagnosis, i.e., acid-fast bacilli (AFB) smear microscopy and culture. We analyzed sputum samples obtained from 133 patients. Results: A total of 48 (36%) cultures yielded indeterminate results due to contamination. This high contamination rate may be explained by the fact that samples from fibrocystic patients were included in this study. Additionally, other five samples were positive for nontuberculous mycobacteria (NTM). Therefore, it was possible to compare 80 patients for M. tuberculosis detection. We found 14 positive samples: five presented positive results in the three methods (5/14; 35.7%), two were positive in culture and PCR (2/14; 14.3%), one was positive in AFB and PCR (1/14; 7.1%), five were positive only in PCR (5/14; 35.7%) and 1 was positive only in culture (1/14; 7.1%). Thus, positivity rates for each technique were: 7.5% for AFB (6/80), 10% for culture (8/80) and 16.25% for PCR (13/80). Among the 48 patients who had indeterminate results in sputum culture, two samples were positive in PCR. Conclusion: Considering the limitations of the traditional methods, the use of PCR as a molecular technique could be advantageous for TB diagnosis.

The Analysis of the Effect of Mixing of Anticoagulant on Nucleic Acid Amplification Tests for Donated Blood / 임상검사와정도관리

BACKGROUND: In the process of implementing the nucleic acid amplification tests (NAT) for the blood screening, it was needed to change plain tube to EDTA tube for the sampling. Because the sample is taken from the CPDA-1 anticoagulated whole blood, the EDTA of tube could be mixed with the CPDA-1. So, we studied the effect of the mixing of two anticoagulants on the NAT. METHODS: Using HIV-1 and HCV RNA standards, we made the qualitative and quantitative test panels for the EDTA anticoagulant and the EDTA/CPDA-1 anticoagulant containing blood. The reverse transcription-polymerase chain reaction of Roche and transcription-mediated amplification of Chiron were used for the RNA qualitative and quantitative test. RESULTS: On the qualitative HIV-1 and HCV RNA tests for the EDTA, CPDA-1 alone and the CPDA-1/EDTA mixture, false negative and false positive reactions were not observed. On quantitative test, viral loads were not different statistically. CONCLUSIONS: Since there were no statistically significant differences between CPDA-1 alone and EDTA/CPDA-1 mixture in both qualitative and quantitative tests for HIV-1 and HCV RNA, it was concluded that mixing of anticoagulants, EDTA and CPDA-1, would not cause an significant effect on the NAT for the donated blood.