A 1-year training program in emergency medicine for physicians in Karachi, Pakistan: Evaluation of learner and program outcomes.

BACKGROUND: Pakistan has an underdeveloped and overburdened emergency care system, with most emergency departments (EDs) staffed by physicians not formally trained in emergency medicine (EM). As of January 2020, only nine Pakistani institutions were providing formal EM specialty training; therefore, a training program of shorter duration is needed in the interim. METHODS: The Certification Program in Emergency Medicine (CPEM) is a 1-year training program in EM consisting of two arms: CPEM-Clinical (CPEM-C), which includes physicians from The Indus Hospital (TIH) ED, and CPEM-Didactic (CPEM-D), including physicians from EDs across Karachi. Both groups participate in weekly conferences, including didactics, small-group discussions, workshops, and journal clubs. CPEM-C learners also receive clinical mentorship from visiting international and TIH EM faculty. Both groups were assessed with preprogram, midterm, and final examinations as well as on clinical skills. Additionally, both groups provided regular feedback on program content and administration. RESULTS: Twenty-five of the 32 initially enrolled learners completed the program in June 2019. Scores on a matched set of 50 questions administered in the pretest and final examination improved by an average of 15.1% (p < 0.005) for CPEM-C learners and 8.5% (p < 0.0005) for CPEM-D learners, with 93% of learners showing improvement. Clinical evaluations of CPEM-C and CPEM-D learners during the first and fourth quarters showed an average improvement of 1.1 out of 5 (p < 0.05) and 1.2 out of 9 (p < 0.0005) points, respectively. Learner evaluations of the program were overall positive. CONCLUSIONS: CPEM demonstrated significant improvement in test scores and clinical evaluations in both program arms. Evaluations also suggested that the program was well received. These data, along with CPEM's ability to train physicians from multiple institutions using low-cost, innovative educational strategies, suggest that it may be an effective, transferable mechanism for the expedited development of EM in Pakistan and countries where EM is developing as a specialty.

Delays in antibiotic redosing: Association with inpatient mortality and risk factors for delay.

OBJECTIVE: Although timely administration of antibiotics has an established benefit in serious bacterial infection, the majority of studies evaluating antibiotic delay focus only on the first dose. Recent evidence suggests that delays in redosing may also be associated with worse clinical outcome. In light of the increasing burden of boarding in Emergency Departments (ED) and subsequent need to redose antibiotic in the ED, we examined the association between delayed second antibiotic dose administration and mortality among patients admitted from the ED with a broad array of infections and characterized risk factors associated with delayed second dose administration. METHODS: We performed a retrospective cohort study of patients admitted through five EDs in a single healthcare system from 1/2018 through 12/2018. Our study included all patients, aged 18 years or older, who received two intravenous antibiotic doses within a 30-h period, with the first dose administered in the ED. Patients with end stage renal disease, cirrhosis and extremes of weight were excluded due to a lack of consensus on antibiotic dosing intervals for these populations. Delay was defined as administration of the second dose at a time-point greater than 125% of the recommended interval. The primary outcome was in-hospital mortality. RESULTS: A total of 5605 second antibiotic doses, occurring during 4904 visits, met study criteria. Delayed administration of the second dose occurred during 21.1% of visits. After adjustment for patient characteristics, delayed second dose administration was associated with increased odds of in-hospital mortality (OR 1.50, 95%CI 1.05-2.13). Regarding risk factors for delay, every one-hour increase in allowable compliance time was associated with a 18% decrease in odds of delay (OR 0.82 95%CI 0.75-0.88). Other risk factors for delay included ED boarding more than 4 h (OR 1.47, 95%CI 1.27-1.71) or a high acuity presentation as defined by emergency severity index (ESI) (OR 1.54, 95%CI 1.30-1.81 for ESI 1-2 versus 3-5). CONCLUSIONS: Delays in second antibiotic dose administration were frequent in the ED and early hospital course, and were associated with increased odds of in-hospital mortality. Several risk factors associated with delays in second dose administration, including ED boarding, were identified.

A whole recombinant yeast-based therapeutic vaccine elicits HBV X, S and Core specific T cells in mice and activates human T cells recognizing epitopes linked to viral clearance.

Chronic hepatitis B infection (CHB) is characterized by sub-optimal T cell responses to viral antigens. A therapeutic vaccine capable of restoring these immune responses could potentially improve HBsAg seroconversion rates in the setting of direct acting antiviral therapies. A yeast-based immunotherapy (Tarmogen) platform was used to make a vaccine candidate expressing hepatitis B virus (HBV) X, surface (S), and Core antigens (X-S-Core). Murine and human immunogenicity models were used to evaluate the type and magnitude of HBV-Ag specific T cell responses elicited by the vaccine. C57BL/6J, BALB/c, and HLA-A*0201 transgenic mice immunized with yeast expressing X-S-Core showed T cell responses to X, S and Core when evaluated by lymphocyte proliferation assay, ELISpot, intracellular cytokine staining (ICS), or tumor challenge assays. Both CD4+ and CD8+ T cell responses were observed. Human T cells transduced with HBc18-27 and HBs183-91 specific T cell receptors (TCRs) produced interferon gamma (IFNγ following incubation with X-S-Core-pulsed dendritic cells (DCs). Furthermore, stimulation of peripheral blood mononuclear cells (PBMCs) isolated from CHB patients or from HBV vaccine recipients with autologous DCs pulsed with X-S-Core or a related product (S-Core) resulted in pronounced expansions of HBV Ag-specific T cells possessing a cytolytic phenotype. These data indicate that X-S-Core-expressing yeast elicit functional adaptive immune responses and supports the ongoing evaluation of this therapeutic vaccine in patients with CHB to enhance the induction of HBV-specific T cell responses.

Augmenting antitumor T-cell responses to mimotope vaccination by boosting with native tumor antigens.

Vaccination with antigens expressed by tumors is one strategy for stimulating enhanced T-cell responses against tumors. However, these peptide vaccines rarely result in efficient expansion of tumor-specific T cells or responses that protect against tumor growth. Mimotopes, or peptide mimics of tumor antigens, elicit increased numbers of T cells that crossreact with the native tumor antigen, resulting in potent antitumor responses. Unfortunately, mimotopes may also elicit cells that do not crossreact or have low affinity for tumor antigen. We previously showed that one such mimotope of the dominant MHC class I tumor antigen of a mouse colon carcinoma cell line stimulates a tumor-specific T-cell clone and elicits antigen-specific cells in vivo, yet protects poorly against tumor growth. We hypothesized that boosting the mimotope vaccine with the native tumor antigen would focus the T-cell response elicited by the mimotope toward high affinity, tumor-specific T cells. We show that priming T cells with the mimotope, followed by a native tumor-antigen boost, improves tumor immunity compared with T cells elicited by the same prime with a mimotope boost. Our data suggest that the improved tumor immunity results from the expansion of mimotope-elicited tumor-specific T cells that have increased avidity for the tumor antigen. The enhanced T cells are phenotypically distinct and enriched for T-cell receptors previously correlated with improved antitumor immunity. These results suggest that incorporation of native antigen into clinical mimotope vaccine regimens may improve the efficacy of antitumor T-cell responses.

Elevated tumor-associated antigen expression suppresses variant peptide vaccine responses.

Variant peptide vaccines are used clinically to expand T cells that cross-react with tumor-associated Ags (TAA). To investigate the effects of elevated endogenous TAA expression on variant peptide-induced responses, we used the GP70 TAA model. Although young BALB/c mice display T cell tolerance to the TAA GP70(423-431) (AH1), expression of GP70 and suppression of AH1-specific responses increases with age. We hypothesized that as TAA expression increases, the AH1 cross-reactivity of variant peptide-elicited T cell responses diminishes. Controlling for immunosenescence, we showed that elevated GP70 expression suppressed AH1 cross-reactive responses elicited by two AH1 peptide variants. A variant that elicited almost exclusively AH1 cross-reactive T cells in young mice elicited few or no T cells in aging mice with Ab-detectable GP70 expression. In contrast, a variant that elicited a less AH1 cross-reactive T cell response in young mice successfully expanded AH1 cross-reactive T cells in all aging mice tested. However, these T cells bound the AH1/MHC complex with a relatively short half-life and responded poorly to ex vivo stimulation with the AH1 peptide. Variant peptide vaccine responses were also suppressed when AH1 peptide is administered tolerogenically to young mice before vaccination. Analyses of variant-specific precursor T cells from naive mice with Ab-detectable GP70 expression determined that these T cells expressed PD-1 and had downregulated IL-7Rα expression, suggesting they were anergic or undergoing deletion. Although variant peptide vaccines were less effective as TAA expression increases, data presented in this article also suggest that complementary immunotherapies may induce the expansion of T cells with functional TAA recognition.

Peptide vaccines prevent tumor growth by activating T cells that respond to native tumor antigens.

Peptide vaccines enhance the response of T cells toward tumor antigens and represent a strategy to augment antigen-independent immunotherapies of cancer. However, peptide vaccines that include native tumor antigens rarely prevent tumor growth. We have assembled a set of peptide variants for a mouse-colon tumor model to determine how to improve T-cell responses. These peptides have similar affinity for MHC molecules, but differ in the affinity of the peptide-MHC/T-cell receptor interaction with a tumor-specific T-cell clone. We systematically demonstrated that effective antitumor responses are generated after vaccination with variant peptides that stimulate the largest proportion of endogenous T cells specific for the native tumor antigen. Importantly, we found some variant peptides that strongly stimulated a specific T-cell clone in vitro, but elicited fewer tumor-specific T cells in vivo, and were not protective. The T cells expanded by the effective vaccines responded to the wild-type antigen by making cytokines and killing target cells, whereas most of the T cells expanded by the ineffective vaccines only responded to the peptide variants. We conclude that peptide-variant vaccines are most effective when the peptides react with a large responsive part of the tumor-specific T-cell repertoire.

Age-dependent tolerance to an endogenous tumor-associated antigen.

Immunologic tolerance to endogenous antigens reduces antitumor responses. Gp70 is an endogenous tumor-associated antigen (TAA) of the BALB/c-derived colon carcinoma CT26. We found that expression of gp70 mRNA is detectable in tissues of mice 8 months of age and older. We showed that expression of gp70 establishes immunologic tolerance and affects antitumor immunity in a similarly age-dependent manner using gp70-deficient mice. We found that tumors grew in all gp70-sufficient mice, while approximately half of gp70-deficient mice controlled tumor growth with endogenous T-cell responses. Protection in gp70-deficient mice correlated with more robust gp70-specific CTL responses, and increased numbers and avidity of responding antigen-specific T cells after vaccination. We conclude that immunosurveillance may decline with age due to increased or de novo peripheral expression of endogenous TAAs.