BackgroundOmicron has become the dominant variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) globally. We aimed to compare the clinical and pulmonary computed tomography (CT) characteristics of the patients infected with SARS-CoV-2 Omicron with those of patients infected with the Alpha viral strain.MethodsClinical profiles and pulmonary CT images of 420 patients diagnosed with coronavirus disease-2019 (COVID-19) at Ningbo First Hospital between January 2020 and April 2022 were collected. Demographic characteristics, symptoms, and imaging manifestations of patients infected with the SARS-CoV-2 Omicron variant were compared with those of patients infected with the Alpha strain.ResultsA total of 38 patients were diagnosed to be infected with the Alpha strain of SARS-CoV-2, whereas 382 patients were thought to be infected with the Omicron variant. Compared with patients infected with the Alpha strain, those infected with the Omicron variant were younger, and a higher proportion of men were infected (P < 0.001). Notably, 93 (24.3%) of the patients infected with Omicron were asymptomatic, whereas only two (5.3%) of the patients infected with the Alpha strain were asymptomatic. Fever (65.8%), cough (63.2%), shortness of breath (21.1%), and diarrhea (21.1%) were more common in patients infected with the SARS-CoV-2 Alpha strain, while runny nose (24.1%), sore throat (31.9%), body aches (13.6%), and headache (12.3%) were more common in patients with the Omicron variant. Compared with 33 (86.84%) of 38 patients infected with the Alpha strain, who had viral pneumonia on pulmonary CT images, only 5 (1.3%) of 382 patients infected with the Omicron variant had mild foci. In addition, the distribution of opacities in the five patients was unilateral and centrilobular, whereas most patients infected with the Alpha strain had bilateral involvement and multiple lesions in the peripheral zones of the lung.ConclusionThe SARS-CoV-2 Alpha strain mainly affects the lungs, while Omicron is confined to the upper respiratory tract in patients with COVID-19.

BackgroundCompared with traditional diagnostic methods (TDMs), rapid diagnostic methods for infectious diseases (IDs) are urgently needed. Metagenomic next-generation sequencing (mNGS) has emerged as a promising diagnostic technology for clinical infections.MethodsThis retrospective observational study was performed at a tertiary hospital in China between May 2019 and August 2022. The chi-square test was used to compare the sensitivity and specificity of mNGS and TDMs. We also performed a subgroup analysis of the different pathogens and samples.ResultsA total of 435 patients with clinical suspicion of infection were enrolled and 372 (85.5%) patients were finally categorized as the ID group. The overall sensitivity of mNGS was significantly higher than that of the TDMs (59.7% vs. 30.1%, P < 0.05). However, there was no significant difference in the overall specificity between the two methods (83.3% vs. 89.6%, P = 0.37). In patients with identified pathogens, the positive rates of mNGS for detecting bacteria (88.7%), fungi (87.9%), viruses (96.9%), and Nontuberculous mycobacteria (NTM; 100%) were significantly higher than those of TDMs (P < 0.05). The positive rate of mNGS for detecting Mycobacterium tuberculosis was not superior to that of TDMs (77.3% vs. 54.5%, P = 0.11). The sensitivity rates of mNGS for pathogen identification in bronchoalveolar lavage fluid, blood, cerebrospinal fluid, pleural fluid, and tissue were 72.6%, 39.3%, 37.5%, 35.0% and 80.0%, respectively.ConclusionWith the potential for screening multiple clinical samples, mNGS has an overall advantage over TDMs. It can effectively identify pathogens, especially those that are difficult to identify using TDMs, such as NTM, chlamydia, and parasites.

Cryptococcosis is an invasive fungal disease with increased morbidity in China. Cryptococci can infect immunocompromised hosts as well as immunocompetent ones. In this study, we reviewed data of inpatients with cryptococcosis at Ningbo First Hospital from May 2010 to May 2020 and compared the clinical profiles of pulmonary cryptococcosis (PC) and extrapulmonary cryptococcosis (EPC). Of 71 patients enrolled, 70 were non-HIV with dramatically increased prevalence especially in PC. 77.46% of cases were PC confirmed by pathology. The rest were EPC including intracranial infection (15.49%) and cryptococcemia (7.04%). Comparing to PC, a larger proportion of EPC patients were found to have immunocompromised conditions including predisposing factors (p<0.01), or detectable humoral or cellular immunodeficiency. Fever and headache were more common in EPC patients (p<0.001). Patients with EPC had lower serum sodium level (p=0.041), lower monocyte counts (p=0.025) and higher C-reactive protein (p=0.012). Cryptococcal antigen tests for serum and cerebrospinal fluid showed 100% sensitivity in diagnosing EPC while serum lateral flow assay (LFA) tested negative in 25% of PC. All in all, underlying immunocompromised conditions may predict dissemination in PC without HIV which can be identified by LFA.