This study aimed to determine the association between different lymphocyte subsets and cytomegalovirus (CMV) infection status in patients with systemic lupus erythematosus (SLE). We performed a retrospective study among SLE patients with CMV infection and collected patient socio-demographic and clinical characteristics, as well as their recorded circulating lymphocyte subsets. Univariate and multivariable logistic regression analyses examined the relationship between CMV infection status and lymphocyte subset counts. We included 125 hospitalized patients with SLE, consisting of 88 with documented CMV infection and 37 without any evidence of CMV or other infections. Among the 88 CMV-infected patients, 65 (73.8%) patients developed CMV disease and 23 (26.2%) presented as CMV viremia. Compared to uninfected patients (1520 ± 101 cells/μL), lymphocytes remained stable among those with CMV viremia (1305 ± 272 cells/μL, P = .995). However, compared to their uninfected counterparts, there was a marked decrease in lymphocytes among patients with CMV disease (680 ± 513 cells/μL, P < .001). Analysis of lymphocyte subsets via flow cytometry showed that CD4+ T cell, CD8+ T cell, and natural killer cell counts were lower among those with CMV disease compared to those with CMV viremia and those without infection. Further, multivariable analysis showed that total lymphocyte (odds ratio [OR] 0.999, 95% confidence interval [CI] 0.998–1.000, P = .007) and CD4+ T cell counts (OR 0.99, 95% CI 0.992–0.998, P = .003) were negatively associated with CMV disease. Our findings support a potential inverse relationship between lymphopenia, specifically CD4+ T-cell lymphopenia, and CMV disease among hospitalized SLE patients.

The source of secondary lower respiratory tract bacterial infections in influenza patients is not fully understood. A casecontrol study was conducted during the 2017-2018 influenza epidemic period in Beijing, China. Nasopharyngeal swabs were collected from 52 virologically confirmed influenza patients and 24 healthy medical staff. The nasopharyngeal microbiota taxonomic composition was analysed using high-throughput sequencing of the 16S rRNA gene V3-V4 regions. The super-dominant pathobiontic bacterial genus (SDPG) was defined as that accounting for >50% of sequences in a nasopharyngeal swab. We attempted to isolate bacteria of this genus from both nasopharyngeal swabs and lower-respiratory tract samples and analyse their genetic similarities. We observed a significantly lower taxonomy richness in influenza cases compared with healthy controls. A SDPG was detected in 61% of severe cases but in only 24% of mild cases and 29% of healthy controls. In 10 cases, the species isolated from lower-respiratory tract infection sites were identified as belonging to the nasopharyngeal microbiota SDPG. Genetically identical strains were isolated from both nasopharyngeal swabs and lower-respiratory tract infection sites, including 23 Acinetobacter baumannii strains from six severe cases, six Klebsiella pneumoniae strains from two severe cases, five Pseudomonas aeruginosa strains from one severe and one mild case, and four Corynebacterium striatum strains from two severe cases. The SDPG in the nasopharyngeal microbiota are the likely cause of subsequent infection in influenza patients.