Macrophage Migration Inhibitory Factor Polymorphisms and Invasive Streptoccus Pneumoniae Infections

Streptococcus pneumoniae[italicized everytime] (S. pneumoniae) causes a spectrum of disease severity, and human host factors likely play a role in this variation. One candidate factor is macrophage migration inhibitory factor (MIF), a pro-inflammatory cytokine and upstream regulator of innate immunity. The MIF[italicized when not in parenthesis] promoter contains two functional polymorphisms, a tetranucleotide (CATT) repeat such that MIF expression increases with repeat number from 5-8 and a single nucleotide polymorphism (SNP) leading to a G-to-C transition, which results in increased MIF expression in cell line reporter assays. Emerging data suggest an association between high-expression MIF alleles and inflammatory disease. This study comprised two parts. For the in vitro portion, we hypothesized that peripheral blood monocytic cells (pBMCs) cultured from healthy individuals with low-expressing MIF genotypes (5-CATT alleles or SNP-GG) would have lower MIF content and release than those from individuals with high-expressing MIF genotypes (7-CATT or SNP-C alleles). For the in vivo study, we hypothesized that individuals with low-expressing MIF genotypes would have less severe systemic inflammatory responses than individuals with high-expressing MIF genotypes in response to S. pneumoniae infection. Blood samples and chart findings were collected prospectively at three Connecticut hospitals from 30 inpatients with documented invasive S. pneumoniae infections. Genomic DNA was isolated from host blood, amplified, and genotyped using fragment analysis (CATT repeat) and allelic discrimination (SNP) methods. Fishers exact tests were used to compare genotypes and disease severity. For the in vitro experiments, there were no differences observed in serum MIF levels or MIF content or release from pBMCs based on MIF genotype. In the cohort of patients infected with S. pneumoniae, serum MIF levels among enrolled subjects were significantly higher than the reported normal values, but levels did not vary with genotype or disease severity. The SNP genotype was not correlated with disease severity or occurrence of meningitis. The CATT genotype did not correlate significantly with disease severity or occurrence of meningitis, although there was a trend suggesting an association between the 7-CATT allele and meningitis (p = 0.1188, 8% without meningitis had a 7-CATT allele vs. 40% with meningitis). More patient samples will need to be analyzed in order to definitively elucidate the role of MIF genetics in infection with S. pneumonia

Increased mortality in hospital- compared to community-onset carbapenem-resistant enterobacterales infections

Abstract Background The CDC reported a 35% increase in hospital-onset (HO) carbapenem-resistant Enterobacterales (CRE) infections during the COVID-19 pandemic. We evaluated patient outcomes following HO and community-onset (CO) CRE bloodstream infections (BSI). Methods Patients prospectively enrolled in CRACKLE-2 from 56 hospitals in 10 countries between 30 April 2016 and 30 November 2019 with a CRE BSI were eligible. Infections were defined as CO or HO by CDC guidelines, and clinical characteristics and outcomes were compared. The primary outcome was desirability of outcome ranking (DOOR) 30 days after index culture. Difference in 30-day mortality was calculated with 95% CI. Results Among 891 patients with CRE BSI, 65% were HO (582/891). Compared to those with CO CRE, patients with HO CRE were younger [median 60 (Q1 42, Q3 70) years versus 65 (52, 74); P < 0.001], had fewer comorbidities [median Charlson comorbidity index 2 (1, 4) versus 3 (1, 5); P = 0.002] and were more acutely ill (Pitt bacteraemia score ≥4: 47% versus 32%; P < 0.001). The probability of a better DOOR outcome in a randomly selected patient with CO BSI compared to a patient with HO BSI was 60.6% (95% CI: 56.8%–64.3%). Mortality at 30-days was 12% higher in HO BSI (192/582; 33%) than CO BSI [66/309 (21%); P < 0.001]. Conclusion We found a disproportionately greater impact on patient outcomes with HO compared to CO CRE BSIs; thus, the recently reported increases in HO CRE infections by CDC requires rigorous surveillance and infection prevention methods to prevent added mortality