Molecular genetic analysis indicates that the problematic human bacterial pathogen methicillin-resistant Staphylococcus aureus possesses more than 2000 open reading frames in its genome. This number of potential gene products, coupled with intrinsic mechanisms of posttranslational modification, endows methicillin-resistant Staphylococcus aureus with a highly complex biochemical repertoire. Recent proteomic and metabolomic advances have provided methodologies to better understand and characterize the biosynthetic factors released by microbial organisms. Here, the emerging tool of mass spectrometry-based molecular networking was used to visualize and map the repertoire of biosynthetic factors produced by a community-associated methicillin-resistant Staphylococcus aureus strain representative of the epidemic USA300 clone. In particular, the study focused on elucidating the complexity of the recently discovered phenol soluble modulin family of peptides when placed under various antibiotic treatment stresses. Novel PSM truncated variant peptides were captured, and the type of variants that were clustered by the molecular networks platform changed in response to the different antibiotic treatment conditions. After discovery, a group of the peptides were selected for functional analysis in vitro. The peptides displayed bioactive properties including the ability to induce proinflammatory responses in human THP-1 monocytes. Additionally, the tested peptides did not display antimicrobial activity as previously reported for other phenol soluble modulin truncated variants. Our findings reveal that the PSM family of peptides are quite structurally diverse, and suggest a single phenol soluble modulin parent peptide can functionally spawn differential bioactivities in response to various external stimuli. Molecular & Cellular Proteomics

Methicillin-resistant Staphylococcus pseudintermedius (MRSP) is an important emerging zoonotic pathogen that causes severe skin infections. To combat infections from drug-resistant bacteria, the transplantation of commensal antimicrobial bacteria as a therapeutic has shown clinical promise. We screened a collection of diverse staphylococcus species from domestic dogs and cats for antimicrobial activity against MRSP. A unique strain (S. felis C4) was isolated from feline skin that inhibited MRSP and multiple gram-positive pathogens. Whole genome sequencing and mass spectrometry revealed several secreted antimicrobials including a thiopeptide bacteriocin micrococcin P1 and phenol-soluble modulin beta (PSMβ) peptides that exhibited antimicrobial and anti-inflammatory activity. Fluorescence and electron microscopy revealed that S. felis antimicrobials inhibited translation and disrupted bacterial but not eukaryotic cell membranes. Competition experiments in mice showed that S. felis significantly reduced MRSP skin colonization and an antimicrobial extract from S. felis significantly reduced necrotic skin injury from MRSP infection. These findings indicate a feline commensal bacterium that could be utilized in bacteriotherapy against difficult-to-treat animal and human skin infections.

It has proved challenging to quantitatively relate the proteome to the transcriptome on a per-gene basis. Recent advances in data analytics have enabled a biologically meaningful modularization of the bacterial transcriptome. We thus investigated whether matched datasets of transcriptomes and proteomes from bacteria under diverse conditions could be modularized in the same way to reveal novel relationships between their compositions. We found that; 1) the modules of the proteome and the transcriptome are comprised of a similar list of gene products, 2) the modules in the proteome often represent combinations of modules from the transcriptome, 3) known transcriptional and post-translational regulation is reflected in differences between two sets of modules, allowing for knowledge-mapping when interpreting module functions, and 4) through statistical modeling, absolute proteome allocation can be inferred from the transcriptome alone. Quantitative and knowledge-based relationships can thus be found at the genome-scale between the proteome and transcriptome in bacteria.

Case series Patients: Female, 34-year-old • Female, 31-year-old • Female, 29-year-old • Female, 24-year-old Final Diagnosis: SARS-CoV-2 Symptoms: Hypoxia Medication: Intravenous immunoglobulin Clinical Procedure: — Specialty: Infectious Diseases Objective: Rare disease Background: Despite unprecedented speed in the execution of the COVID-19 vaccine and therapeutic clinical trials, pregnant patients have been largely excluded from initial studies. In addition, pregnant patients who are unvaccinated against SARS-CoV-2 have greater morbidity risk with severe COVID-19 disease as compared to patients of similar age and comorbidity status. Intravenous immunoglobulin (IVIG) has been deemed safe in pregnancy in other diseases. Prior data demonstrate the possible benefit of utilizing IVIG for the treatment in hospitalized patients with severe respiratory symptoms associated with COVID-19 active infections when administered within 14 days of COVID symptom onset. Case Reports: We administered IVIG (Privigen ® , CSL Behring) 0.5 g/kg daily for 3 consecutive days to 4 pregnant patients (ages 24-34 years of age) who were hospitalized with moderate-to-severe COVID-19 and not vaccinated against SARS-CoV-2. All patients received concomitant glucocorticoid therapy. Gestational ages were 26, 17, 35, and 35 weeks. All patients were discharged home breathing room air after a mean hospital stay of 15 days. Two patients had uncomplicated cesarean section at 35 weeks during the hospitalization. The pre-term pregnancies at 17 and 26 weeks were intact at hospital discharge and resulted in normal vaginal deliveries at term. All 4 patients consented to participate in this case series report. Conclusions: IVIG may be a safe treatment consideration in pregnant women with severe COVID-19 to avoid pregnancy complications. Its use warrants further study in pregnancy acute respiratory distress syndrome (ARDS) due to SARS-CoV-2, influenza, and other respiratory viruses to which pregnant patients are vulnerable.