Significance: We detail host–pathogen interaction gene-expression profiles of Streptococcus pneumoniae ( Spn ) and its infected host at disease relevant anatomical sites using mice as experimental models. We identify the shared and organ-specific transcriptomes of Spn , show that bacterial and host gene-expression profiles are highly distinct during asymptomatic colonization versus disease-causing infection, and demonstrate that Spn and host genes with high levels of expression contribute to pathogenesis or host defense, respectively, making them optimal targets for intervention.

Streptococcus pneumoniae (Spn) alone and during co-infection with influenza A virus (IAV) can result in severe pneumonia with mortality. Pneumococcal surface protein A (PspA) is an established virulence factor required for Spn evasion of lactoferricin and C-reactive protein-activated complement-mediated killing. Herein, we show that PspA functions as an adhesin to dying host cells. We demonstrate that PspA binds to host-derived glyceraldehyde-3-phosphate dehydrogenase (GAPDH) bound to outward-flipped phosphatidylserine residues on dying host cells. PspA-mediated adhesion was to apoptotic, pyroptotic, and necroptotic cells, but not healthy lung cells. Using isogenic mutants of Spn, we show that PspA-GAPDH-mediated binding to lung cells increases pneumococcal localization in the lower airway, and this is enhanced as a result of pneumolysin exposure or co-infection with IAV. PspA-mediated binding to GAPDH requires amino acids 230-281 in its α-helical domain with intratracheal inoculation of this PspA fragment alongside the bacteria reducing disease severity in an IAV/Spn pneumonia model.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes severe lower airway disease and death in a subset of patients. Knowledge on the relative contribution of programmed cell death (PCD) to lung pathology is limited to few human autopsy studies with small sample size/scope, in vitro cell culture, and experimental model systems. In this study, we sought to identify, localize, and quantify activation of apoptosis, ferroptosis, pyroptosis, and necroptosis in FFPE lung tissues from patients that died from severe SARS-CoV-2 infection (n = 28) relative to uninfected controls (n = 13). Immunofluorescence (IF) staining, whole-slide imaging, and Image J software was used to localize and quantify expression of SARS-CoV-2 nucleoprotein and the following PCD protein markers: cleaved Caspase-3, pMLKL, cleaved Gasdermin D, and CD71, respectively. IF showed differential activation of each PCD pathway in infected lungs and dichotomous staining for SARS-CoV-2 nucleoprotein enabling distinction between high (n = 9) vs low viral burden (n = 19). No differences were observed in apoptosis and ferroptosis in SARS-CoV-2 infected lungs relative to uninfected controls. However, both pyroptosis and necroptosis were significantly increased in SARS-CoV-2-infected lungs. Increased pyroptosis was observed in SARS-CoV-2 infected lungs, irrespective of viral burden, suggesting an inflammation-driven mechanism. In contrast, necroptosis exhibited a very strong positive correlation with viral burden (R² = 0.9925), suggesting a direct SARS-CoV-2 mediated effect. These data indicate a possible novel mechanism for viral-mediated necroptosis and a potential role for both lytic programmed cell death pathways, necroptosis and pyroptosis, in mediating infection outcome.

Aims: To evaluate the performance of two matrix-assisted laser desorption/ionization–time-of-flight mass spectrometry platforms to identify molds isolated from clinical specimens. Methods: Fifty mo... Plain language summary There are two different mass spectrometry systems that can be used in the hospital laboratory to find out what kind of mold is growing from a patient sample: the Vitek® MS an...

Key bacterial vaginosis (BV)-associated bacteria implicated in biofilm formation include Gardnerella species, Prevotella bivia , and Fannyhessea vaginae . We investigated their spatial organization in the BV biofilm over time from longitudinal vaginal specimens obtained from women with incident BV (iBV) using peptide nucleic acid-fluorescence in situ hybridization (PNA-FISH). Heterosexual women with optimal vaginal microbiota self-collected vaginal specimens twice daily for 60 days or until iBV development (Nugent score 7–10 on ≥4 consecutive specimens). Women who developed iBV were matched to healthy controls by age, race, and contraceptive method. Gardnerella spp., P. bivia , and F. vaginae were quantified using PNA-FISH 2 days pre-iBV, the day of iBV, and 2 days post-iBV across five optical layers ( z , z + 2, z + 4, z + 6, and z + 8 μm). Total counts of all three bacterial species were significantly higher on the day of iBV compared to 2 days pre-iBV ( P = 0.011) and remained elevated 2 days post-iBV. Across most layers and time points, pooled mean Gardnerella spp. counts were significantly higher than F. vaginae counts ( P ≤ 0.022-0.0003). On the day of iBV and 2 days post-iBV, pooled mean counts of Gardnerella spp. and F. vaginae progressively increased across most biofilm layers ( P ≤ 0.043-0.0012). Controls had significantly lower counts of Gardnerella spp. and F. vaginae. P. bivia had low counts in all specimens. During the critical time period surrounding iBV, Gardnerella spp. are abundant throughout the developing biofilm and facilitate F. vaginae incorporation at later time points and higher biofilm layers. Additional research, including other Prevotella spp., is needed. IMPORTANCE: Bacterial vaginosis (BV) is the most common vaginal infection in reproductive-age women worldwide with a global prevalence of 30%. Recurrence rates can be up to 60% within 1 year of treatment. While BV is characterized as a polymicrobial biofilm infection, the exact etiology remains unknown. The BV biofilm may persist after antibiotic treatment, possibly due to incomplete eradication by current antimicrobial therapies, contributing to recurrent infection. Data are limited in evaluating the spatial formation of the BV biofilm around the time of incident BV. Providing a better understanding of this critical time period in incident BV pathogenesis is necessary to inform the development of prevention methods aimed at inhibiting biofilm formation and improving long-term treatment outcomes.

Background: Bacterial vaginosis (BV) is a vaginal dysbiosis characterized by polymicrobial communities of BV-associated bacteria (BVAB) adhered to the vaginal epithelium. Despite decades of research, its etiology remains unknown. We aimed to investigate BV biofilm formation over time among women who developed incident BV (iBV) using peptide nucleic acid-fluorescence in situ hybridization (PNA-FISH), focusing on 3 key BVAB (Gardnerella species, Prevotella bivia, and Fannyhessea vaginae). Methods: Heterosexual, nonpregnant women ages 18–45 with optimal vaginal microbiota were enrolled to self-collect twice-daily vaginal specimens for 60 days. iBV was defined as a Nugent score of 7–10 on ≥4 consecutive specimens. For women who developed iBV (cases), Gardnerella spp., P. bivia, and F. vaginae were visualized and quantified by PNA-FISH for up to 14 days prior to iBV, the day of iBV, and 3 days post-iBV. Cases were matched to women maintaining optimal vaginal microbiota (controls) based on age, race, and contraceptive method. Control specimens were matched to case specimens by day of menses. Results: Among 135 women enrolled, 18 developed iBV and were matched to 18 controls. Pooled median Gardnerella spp. counts significantly increased starting 5 days before iBV, while pooled median F. vaginae counts significantly increased on the day of iBV diagnosis. In contrast, pooled median P. bivia counts were not significantly different between groups. Conclusions: These data suggest that Gardnerella spp. are early colonizers of the BV biofilm while F. vaginae is a secondary colonizer. P. bivia was not found to be significantly different between iBV case and control specimens.