Clinical characteristics and risk factors for bacterial co-infections in COVID-19 patients: A retrospective study.

OBJECTIVE: This study aimed to analyse the bacterial composition, distribution, drug sensitivity, and clinical characteristics of patients with coronavirus disease 2019 (COVID-19) who develop bacterial co-infections. METHODS: We conducted a retrospective study of 184 patients with COVID-19 admitted between December 2022 and January 2023. Data on gender, age, length of hospital stay, pneumonia classification, underlying diseases, invasive surgery, hormone therapy, inflammation indicators, and other relevant information were collected. Samples of sputum, bronchoscopy sputum, alveolar lavage fluid, middle urine, puncture fluid, wound secretions, and blood were collected for pathogen isolation, identification, and drug sensitivity testing. RESULTS: The majority of patients with COVID-19 with bacterial co-infection were elderly and had underlying diseases. Invasive surgery and hormone therapy were identified as risk factors for co-infections. Laboratory analysis showed reduced lymphocyte counts and elevated levels of C-reactive protein and procalcitonin. The most common pathogens in co-infections were Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa. The detection rate of drug-resistant strains, including methicillin-resistant S. aureus, carbapenem-resistant K. pneumoniae, carbapenem-resistant A. baumannii, carbapenem-resistant P. aeruginosa, and carbapenem-resistant E. coli, increased with the severity of pneumonia. CONCLUSION: Respiratory tract infections were the most common site of bacterial co-infection in patients with COVID-19. Severe cases were more susceptible to multidrug-resistant pathogens, leading to a higher mortality rate. Timely control and prevention of co-infection are crucial for improving the prognosis of patients with COVID-19.

High-sensitivity hemoglobin detection based on polarization-differential spectrophotometry.

Hemoglobin content is recognized as a momentous and fundamental physiological indicator, especially the precise detection of trace hemoglobin is of great significance for early diagnosis and prevention of tumors, cancer, organic injury, etc. Therefore, high-sensitivity hemoglobin detection is imperative. However, effective detection methods and reliable detection systems are still lacking and remain enormous challenges. Herein, we present a synthetical strategy to break through the existing bottleneck based on polarization-differential spectrophotometry and high-performance single-frequency green fiber laser. Importantly, this framework not only has precisely extracted the two-dimensional information of intensity and polarization during the interaction between laser and hemoglobin, but also has taken advantage of the high monochromaticity and fine directivity in the optimized laser source to reduce the undesirable scattered disturbance. Thus, the hemoglobin detection sensitivity of 7.2 × 10-5 g/L has advanced a hundredfold compared with conventional spectrophotometry, and the responsive dynamic range is close to six orders of magnitude. Results indicate that our technology can realize high-sensitivity detection of trace hemoglobin content, holding promising applications for precision medicine and early diagnosis as an optical direct and fast detection method.

Mycobacterium tuberculosis peptide E7/HLA-DRB1 tetramers with different HLA-DR alleles bound CD4+ T cells might share identical CDR3 region.

Human CD4+ T cells play an important role in the immune response to Mycobacterium tuberculosis (MTB). However, little is known about the spectratyping characteristics of the CD4+ T-cell receptor (TCR) α- and ß-chains CDR3 region in tuberculosis (TB) patients. We sorted MTB peptide E7-bound CD4+ T cells by using E7/HLA-DR tetramers constructed with different HLA-DRB1 alleles and extracted the CDR3 amino-acid sequences of TCR α- and ß-chains. The results showed that the CDR3 sequences of E7-bound CD4+ T cells were completely or partially identical in a single patient. The sequences of MTB peptide C5-bound CD4+ T cells shared another, and non-peptide bound CD4+ T cells, as well as unbound CD4+ T cells with tetramers were different from each other. Specifically, diverse CDR3 sequences of E7-bound CD4+ T cells displayed similar protein tertiary structure in one TB patient. In summary, the TCR α- and ß-chains of CDR3 lineage of CD4+ T cells in TB patients apparently drifted, and the predominant CDR3 sequences of TCR α- and ß-chains that recognized the MTB antigen exhibited peptide specificity, and certain HLA-DR restriction was also established. This study elucidates the possible causes and mechanisms of peptide-specific CD4+ T-cell-related presentation against MTB.