Mucosal and Systemic Responses to Severe Acute Respiratory Syndrome Coronavirus 2 Vaccination Determined by Severity of Primary Infection.

With much of the world infected with or vaccinated against severe acute respiratory syndrome coronavirus 2 (commonly abbreviated SARS-CoV-2; abbreviated here SARS2), understanding the immune responses to the SARS2 spike (S) protein in different situations is crucial to controlling the pandemic. We studied the clinical, systemic, mucosal, and cellular responses to two doses of SARS2 mRNA vaccines in 62 individuals with and without prior SARS2 infection that were divided into three groups based on antibody serostatus prior to vaccination and/or degree of disease symptoms among those with prior SARS2 infection: antibody negative (naive), low symptomatic, and symptomatic. Antibody negative were subjects who were antibody negative (i.e., those with no prior infection). Low symptomatic subjects were those who were antibody negative and had minimal or no symptoms at time of SARS2 infection. Symptomatic subjects were those who were antibody positive and symptomatic at time of SARS2 infection. All three groups were then studied when they received their SARS2 mRNA vaccines. In the previously SARS2-infected (based on antibody test) low symptomatic and symptomatic groups, reactogenic symptoms related to a recall response were elicited after the first vaccination. Anti-S trimer IgA and IgG titers, and neutralizing antibody titers, peaked after the 1st vaccination in the previously SARS2-infected groups and were significantly higher than for the SARS2 antibody-negative group in the plasma and nasal samples at most time points. Nasal and plasma IgA antibody responses were significantly higher in the low symptomatic group than in the symptomatic group at most time points. After the first vaccination, differences in cellular immunity were not evident between groups, but the activation-induced cell marker (AIM+) CD4+ cell response correlated with durability of IgG humoral immunity against the SARS2 S protein. In those SARS2-infected subjects, severity of infection dictated plasma and nasal IgA responses in primary infection as well as response to vaccination (peak responses and durability), which could have implications for continued protection against reinfection. Lingering differences between the SARS2-infected and SARS2-naive up to 10 months postvaccination could explain the decreased reinfection rates in the SARS2-infected vaccinees recently reported and suggests that additional strategies (such as boosting of the SARS2-naive vaccinees) are needed to narrow the differences observed between these groups. IMPORTANCE This study on SARS2 vaccination in those with and without previous exposure to the virus demonstrates that severity of infection dictates IgA responses in primary infection as well as response to vaccination (peak responses and durability), which could have implications for continued protection against reinfection.

Human Pleural Fluid Elicits Pyruvate and Phenylalanine Metabolism in Acinetobacter baumannii to Enhance Cytotoxicity and Immune Evasion.

Acinetobacter baumannii (Ab) is one of the most treacherous pathogens among those causing hospital-acquired pneumonia (HAP). A. baumannii possesses an adaptable physiology, seen not only in its antibiotic resistance and virulence phenotypes but also in its metabolic versatility. In this study, we observed that A. baumannii undergoes global transcriptional changes in response to human pleural fluid (PF), a key host-derived environmental signal. Differential gene expression analyses combined with experimental approaches revealed changes in A. baumannii metabolism, affecting cytotoxicity, persistence, bacterial killing, and chemotaxis. Over 1,220 genes representing 55% of the differentially expressed transcriptomic data corresponded to metabolic processes, including the upregulation of glutamate, short chain fatty acid, and styrene metabolism. We observed an upregulation by 1.83- and 2.61-fold of the pyruvate dehydrogenase complex subunits E3 and E2, respectively. We also found that pyruvate (PYR), in conjunction with PF, triggers an A. baumannii pathogenic behavior that adversely impacts human epithelial cell viability. Interestingly, PF also amplified A. baumannii cytotoxicity against murine macrophages, suggesting an immune evasion strategy implemented by A. baumannii. Moreover, we uncovered opposing metabolic strategies dependent on the degree of pathogenicity of the strains, where less pathogenic strains demonstrated greater utilization of PYR to promote persister formation in the presence of PF. Additionally, our transcriptomic analysis and growth studies of A. baumannii suggest the existence of an alternative phenylalanine (PA) catabolic route independent of the phenylacetic acid pathway, which converts PA to phenylpyruvate (PP) and shuttles intermediates into styrene metabolism. This alternative route promoted a neutrophil-evasive state, as PF-induced degradation of PP significantly reduced overall human neutrophil chemotaxis in ex vivo chemotactic assays. Taken together, these data highlight A. baumannii pathoadaptabililty in response to host signals and provide further insight into the role of bacterial metabolism in virulence traits, antibiotic persistence strategies, and host innate immune evasion.

Inflammatory production of reactive oxygen species by Drosophila hemocytes activates cellular immune defenses.

The production of reactive oxygen species (ROS) is a prominent response to infection among innate immune cells such as macrophages and neutrophils. To better understand the relationship between antimicrobial and regulatory functions of blood cell ROS, we have characterized the ROS response to infection in Drosophila hemocytes. Using fluorescent probes, we find a biphasic hemocyte ROS response to bacterial infection. In the first hour, virtually all hemocytes generate a transient ROS signal, with nonphagocytic cells including prohemocytes and crystal cells displaying exceptionally strong responses. A distinct, and more delayed ROS response starting at 90 min is primarily within cells that have engulfed bacteria, and is sustained for several hours. The early response has a clear regulatory function, as dampening or intensifying the intracellular ROS level has profound effects on plasmatocyte activation. In addition, ROS are necessary and sufficient to activate JNK signalling in crystal cells, and to promote JNK-dependent crystal cell rupture. These findings indicate that Drosophila will be a promising model in which to dissect the mechanisms of ROS stimulation of immune activation.

Using reflection to evaluate student learning in ambulatory care IPPEs.

PURPOSE: Gather insight from student pharmacists about what they learned and whether objectives of an introductory pharmacy practice experience (IPPE) were achieved in an academic-based ambulatory care site. METHODS: Students wrote post-reflective essays after their first ambulatory care-site visit. They reflected upon their previous assumptions of ambulatory care, and the roles and skills required of pharmacists in this setting. Additionally, students ranked their interest in ambulatory care pre- and post-IPPE. Post-reflection essays were analyzed for recurring themes using a constant comparison method and a respondent validation method was employed to confirm these findings. Wilcoxon signed-rank sum test was used to analyze student interest in ambulatory care and descriptive statistics were used, as appropriate. RESULTS: Overall, 70 reflection articles were analyzed. Assumptions of ambulatory care were either incorrect or proved to be more than what was expected for 60% of students. Based on the themes identified, students learned most about the collaborative practice model, chronic disease state management, and the time commitment necessary for outcomes. Regarding skills required of a pharmacist, students discussed the need for a strong knowledge base, communication, and ability to transfer these skills from one setting to another. Interest in ambulatory care increased after the site visit (p <0.01) and 90% of students who wrote these reflections strongly agreed or agreed with the above findings. CONCLUSIONS: With intentional reflection, ambulatory care IPPEs can serve as a meaningful outlet for learning while also achieving IPPE objectives.

Infection control link nurse program: an interdisciplinary approach in targeting health care-acquired infection.

BACKGROUND: We describe a successful interdisciplinary liaison program that effectively reduced health care-acquired (HCA), methicillin-resistant Staphylococcus aureus (MRSA) in a university hospital setting. METHODS: Baseline was from January 2006 to March 2008, and intervention period was April 2008 to September 2009. Staff nurses were trained to be liaisons (link nurses) to infection prevention (IP) personnel with clearly defined goals assigned and with ongoing monthly education. HCA-MRSA incidence per 1,000 patient-days (PD) was compared between baseline and intervention period along with total and non-HCA-MRSA, HCA and non-HCA-MRSA bacteremia, and hand soap/sanitizer usage. Hand hygiene compliance was assessed. RESULTS: A reduction in MRSA rates was as follows in intervention period compared with baseline: HCA-MRSA decreased by 28% from 0.92 to 0.67 cases per 1,000 PD (incidence rate ratio, 0.72; 95% confidence interval: 0.62-0.83, P < .001), and HCA-MRSA bacteremia rate was reduced by 41% from 0.18 to 0.10 per 1,000 PD (incidence rate ratio, 0.59; 95% confidence interval: 0.42-0.84, P = .003). Total MRSA rate and MRSA bacteremia rate also showed significant reduction with nonsignificant reductions in overall non-HCA-MRSA and non-HCA-MRSA bacteremia. Hand soap/sanitizer usage and compliance with hand hygiene also increased significantly during IP. CONCLUSION: Link nurse program effectively reduced HCA-MRSA. Goal-defined metrics with ongoing re-education for the nurses by IP personnel helped drive these results.