Reliable Negative Results Research Articles

Clinical Features and Temporal Changes of RT-PCR and Chest CT in COVID-19 Pediatric Patients.

Objective: This work aims to investigate the clinical features and the temporal changes of RT-PCR and CT in COVID-19 pediatric patients.Methods: The clinical, RT-PCR, and CT features of 114 COVID-19 pediatric in-patients were retrospectively reviewed from January 21 to March 14, 2020. All patients had chest CT on admission and were identified as positive by pharyngeal swab nucleic acid test. The clinical features were analyzed, as well as the features and the temporal changes of RT-PCR and CT.Results: Fever (62, 54%) and cough (61, 54%) were the most common symptoms. There were 34 (30%) cases of concurrent infections. The most common imaging features on CT were ground-glass opacities (46, 40%) and consolidation (46, 40%). The bilateral lower lobes were the most common pattern of involvement, with 63 cases (55%) involving one to two lobes, and in 32 (28%) cases CT was normal. Throughout the whole duration of COVID-19 in children, the diagnostic positive rate of RT-PCR has been far higher than that of CT (all P < 0.05). For RT-PCR follow-up, reliable negative results were obtained only 7 days after the onset of symptoms. Though lung involvement on chest CT progressed rapidly in several cases, lung involvement in children with COVID-19 is mild, with a median value of 2 on CT score.Conclusions: RT-PCR is more reliable than CT in the initial diagnosis of pediatric patients with COVID-19. On follow-up, reliable negative RT-PCR results are available 7 days after the initial symptoms. The use of CT should be considered for follow-up purposes only if necessary.

Real-time multiplex PCR for direct detection of methicillin-resistant Staphylococcus aureus (MRSA) in clinical samples enriched by broth culture

A real-time multiplex PCR using the orfX and staphylococcal cassette chromosome (SCC) mec of Staphylococcus aureus was developed. The aim was to achieve a rapid and sensitive high-throughput method for direct detection of heterogeneous methicillin-resistant S. aureus (MRSA) in clinical samples, present in a low-endemic population, such as in Sweden. Consecutive broth enriched pooled clinical screening samples (nares, throat and/or perineum/groin) (n = 541 pools), broth enriched clinical samples showing growth of methicillin-sensitive S. aureus (MSSA) (n = 95 pools), clinical MRSA isolates (n = 173), MRSA reference strains (n = 43) and various coagulase-negative staphylococcal isolates (n = 33) were analyzed. The multiplex PCR detected all heterogeneous MRSA strains (n = 173) obtained in our area as well as all pooled consecutive broth enriched clinical samples with MRSA, i. e. 36 of 541 pools. None of the CoNS were positive. However, 18 out of 541 pools (3.3%) were positive in the multiplex PCR but no growth of MRSA could be detected by subculture and were regarded as false positive. Furthermore, the assay is rapid and reliable negative results can be delivered to the clinician within 18 h that will facilitate the infection control management of patients and hospital staff.

Twelve hour real-time PCR technique for the sensitive and specific detection of Salmonella in raw and ready-to-eat meat products

Rapid pathogen testing is vital to the food industry. Enzyme immunoassays (EIA) provide reliable negative results in 48 h, but a presumptive positive (suspect) EIA result must be confirmed by traditional culture methods, requiring an additional 72 h. Polymerase chain reaction (PCR) testing technology is accepted as an accurate diagnostic tool. However, traditional PCR techniques can require several days. We sought to develop a rapid, real-time quantitative PCR technique for detecting Salmonella spp. in food products. Salmonella spp. was inoculated into raw and ready-to-eat beef products. Total DNA was extracted and used as template for PCR amplification in the LightCycler (Roche Diagnostics Corp., Idaho Technology Inc., Idaho Falls, ID) PCR instrument. Salmonella-specific PCR primers were designed to amplify a 251 base pair product from the junction of SipB and SipC. Fluorescently-labeled hybridization probes were designed to anneal to SipB and SipC. Salmonella was detected down to 1 colony forming unit/ml in food products. The results of real-time PCR correlated 100% to those of visual immunoprecipitate and culture. PCR methods using the LightCycler can detect and confirm the presence or absence of Salmonella spp. in raw and ready-to-eat beef products within 12 h with increased sensitivity compared to traditional culture and EIA methods.

A review of the MMPI in industry.

The present paper has presented extensive evidence that is critical of the industrial uses of the MMPI. This criticism is not intended to discourage use of the inventory in industrial settings. Rather, it is hoped that it will stimulate published research on a variety of topics. Most of the criticism has resulted from the unvalidated uses of the MMPI. Evidence, as can be readily seen, is inconclusive concerning many applications of the inventory. Although the exact number of companies which use the MMPI is not known, it appears that many industrial firms do, and they may carry on an active program of research. This research, due to quality, hesitancy of a company to be identified, or competitive business ethics, is rarely published. The author submits that this practice is not only damaging to the business world, but it is also professionally unsound. Even reliable negative results would furnish guidelines for future applications of and research with the MMPI.