IL-18R-mediated HSC quiescence and MLKL-dependent cell death limit hematopoiesis during infection-induced shock.

Severe infection can dramatically alter blood production, but the mechanisms driving hematopoietic stem and progenitor cell (HSC/HSPC) loss have not been clearly defined. Using Ixodes ovatus Ehrlichia (IOE), a tick-borne pathogen that causes severe shock-like illness and bone marrow (BM) aplasia, type I and II interferons (IFNs) promoted loss of HSPCs via increased cell death and enforced quiescence. IFN-αß were required for increased interleukin 18 (IL-18) expression during infection, correlating with ST-HSC loss. IL-18 deficiency prevented BM aplasia and increased HSC/HSPCs. IL-18R signaling was intrinsically required for ST-HSC quiescence, but not for HSPC cell death. To elucidate cell death mechanisms, MLKL- or gasdermin D-deficient mice were infected; whereas Mlkl-/- mice exhibited protected HSC/HSPCs, no such protection was observed in Gsdmd-/- mice during infection. MLKL deficiency intrinsically protected HSCs during infection and improved hematopoietic output upon recovery. These studies define MLKL and IL-18R signaling in HSC loss and suppressed hematopoietic function in shock-like infection.

A Novel Peptide Antibiotic, Pro10-1D, Designed from Insect Defensin Shows Antibacterial and Anti-Inflammatory Activities in Sepsis Models.

Owing to the challenges faced by conventional therapeutics, novel peptide antibiotics against multidrug-resistant (MDR) gram-negative bacteria need to be urgently developed. We had previously designed Pro9-3 and Pro9-3D from the defensin of beetle Protaetia brevitarsis; they showed high antimicrobial activity with cytotoxicity. Here, we aimed to develop peptide antibiotics with bacterial cell selectivity and potent antibacterial activity against gram-negative bacteria. We designed 10-meric peptides with increased cationicity by adding Arg to the N-terminus of Pro9-3 (Pro10-1) and its D-enantiomeric alteration (Pro10-1D). Among all tested peptides, the newly designed Pro10-1D showed the strongest antibacterial activity against Escherichia coli, Acinetobacter baumannii, and MDR strains with resistance against protease digestion. Pro10-1D can act as a novel potent peptide antibiotic owing to its outstanding inhibitory activities against bacterial film formation with high bacterial cell selectivity. Dye leakage and scanning electron microscopy revealed that Pro10-1D targets the bacterial membrane. Pro10-1D inhibited inflammation via Toll Like Receptor 4 (TLR4)/Nuclear factor-κB (NF-κB) signaling pathways in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Furthermore, Pro10-1D ameliorated multiple-organ damage and attenuated systemic infection-associated inflammation in an E. coli K1-induced sepsis mouse model. Overall, our results suggest that Pro10-1D can potentially serve as a novel peptide antibiotic for the treatment of gram-negative sepsis.

Shock and Early Death in Hematologic Patients with Febrile Neutropenia.

Empirical antibiotic therapy with a beta-lactam is the standard of care in febrile neutropenia (FN) and is given to prevent early death. The addition of vancomycin is recommended in certain circumstances, but the quality of evidence is low, reflecting the lack of clinical data. In order to characterize the epidemiology of early death and shock in FN, we reviewed all episodes of FN from 2003 to 2017 at University Hospital, Federal University of Rio de Janeiro, and looked at factors associated with shock at first fever and early death (within 3 days from first fever) by univariate and multivariate analyses. Among 1,305 episodes of FN, shock occurred in 42 episodes (3.2%) and early death in 15 (1.1%). Predictors of shock were bacteremia due to Escherichia coli (odds ratio [OR], 8.47; 95% confidence interval [95% CI], 4.08 to 17.55; P < 0.001), Enterobacter sp. (OR, 7.53; 95% CI, 1.60 to 35.33; P = 0.01), and Acinetobacter sp. (OR, 6.95; 95% CI, 1.49 to 32.36; P = 0.01). Factors associated with early death were non-Hodgkin's lymphoma (OR, 3.57; 95% CI, 1.18 to 10.73; P = 0.02), pneumonia (OR, 21.36; 95% CI, 5.72 to 79.72; P < 0.001), shock (OR, 11.64: 95% CI, 2.77 to 48.86; P = 0.01), and bacteremia due to Klebsiella pneumoniae (OR, 5.91; 95% CI, 1.11 to 31.47; P = 0.03). Adequate empirical antibiotic therapy was protective (OR, 0.23; 95% CI, 0.07 to 0.81; P = 0.02). Shock or early death was not associated with Gram-positive bacteremia; catheter-related, skin, or soft tissue infection; or inadequate Gram-positive coverage. These data challenge guideline recommendations for the empirical use of vancomycin at first fever in neutropenic patients.

A rare presentation of hypovolemic shock secondary to Whipple's disease.

Whipple's disease is a rare, multisystem infection caused by the Gram-positive Tropheryma whippelii organism. In addition to neurological and rheumatological manifestations, this disease can result in significant gastrointestinal symptoms such as malabsorption, diarrhea, and weight loss. Given the diagnostic challenge and rare occurrence, a high index of suspicion is critical to prevent morbidity and mortality from this otherwise highly infectious disease transmitted via the fecal-oral route. We present a very rare but near-fatal case of hypovolemic shock secondary to protein-losing enteropathy and gastrointestinal bleeding from small bowel T. whippelii infection. Furthermore, the epidemiology, clinical presentation, diagnosis, and management of Whipple's disease is reviewed.

Type I IFNs drive hematopoietic stem and progenitor cell collapse via impaired proliferation and increased RIPK1-dependent cell death during shock-like ehrlichial infection.

Type I interferons (IFNα/ß) regulate diverse aspects of host defense, but their impact on hematopoietic stem and progenitor cells (HSC/HSPCs) during infection remains unclear. Hematologic impairment can occur in severe infections, thus we sought to investigate the impact of type I IFNs on hematopoiesis in a tick-borne infection with a virulent ehrlichial pathogen that causes shock-like disease. During infection, IFNα/ß induced severe bone marrow (BM) loss, blunted infection-induced emergency myelopoiesis, and reduced phenotypic HSPCs and HSCs. In the absence of type I IFN signaling, BM and splenic hematopoiesis were increased, and HSCs derived from Ifnar1-deficient mice were functionally superior in competitive BM transplants. Type I IFNs impaired hematopoiesis during infection by both limiting HSC/HSPC proliferation and increasing HSPC death. Using mixed BM chimeras we determined that type I IFNs restricted proliferation indirectly, whereas HSPC death occurred via direct IFNαR -mediated signaling. IFNαR-dependent signals resulted in reduced caspase 8 expression and activity, and reduced cleavage of RIPK1 and RIPK3, relative to Ifnar1-deficient mice. RIPK1 antagonism with Necrostatin-1s rescued HSPC and HSC numbers during infection. Early antibiotic treatment is required for mouse survival, however antibiotic-treated survivors had severely reduced HSPCs and HSCs. Combination therapy with antibiotics and Necrostatin-1s improved HSPC and HSC numbers in surviving mice, compared to antibiotic treatment alone. We reveal two mechanisms whereby type I IFNs drive hematopoietic collapse during severe infection: direct sensitization of HSPCs to undergo cell death and enhanced HSC quiescence. Our studies reveal a strategy to ameliorate the type I IFN-dependent loss of HSCs and HSPCs during infection, which may be relevant to other infections wherein type I IFNs cause hematopoietic dysfunction.

Extracorporeal Membrane Oxygenation as a Bridge to Surgery for Infective Endocarditis Complicated by Aorto-Atrial Fistula and Cardiopulmonary Collapse.

The timing of surgery for active infective endocarditis is challenging when patients exhibit mechanical dysfunction and hemodynamic compromise. Extracorporeal membrane oxygenation has been described in treating sepsis but not, insofar as we know, in treating the acute mechanical sequelae that arise from infective endocarditis. We report perhaps the first case that shows the usefulness of extracorporeal membrane oxygenation as a bridge to definitive treatment in a 35-year-old man who had infective endocarditis followed by aorto-atrial fistula and cardiopulmonary collapse.

Spirocheatal shock syndrome.

In this paper we describe a clinical scenario of high grade fever, jaundice, hypotension and multi-organ dysfunction syndrome in a 30-year-old homeless male without radiological biliary obstruction. He was brought to our hospital by the emergency medical service of Saudi Arabia (Red Crescent) from the street. After an initial resuscitation he proved to have Borrelia recurrentis. The clinical course during his hospital stay was not a smooth one, but the patient finally improved. After 20 days of hospitalisation, he was discharged in a stable condition. The present case underlines the need for high clinical vigilance, even in a non-endemic area.

Infectious shock and toxic shock syndrome diagnoses in hospitals, Colorado, USA.

In Colorado, USA, diagnoses coded as toxic shock syndrome (TSS) constituted 27.3% of infectious shock cases during 1993-2006. The incidence of staphylococcal TSS did not change significantly overall or in female patients 10-49 years of age but increased for streptococcal TSS. TSS may be underrecognized among all ages and both sexes.

B. anthracis associated cardiovascular dysfunction and shock: the potential contribution of both non-toxin and toxin components.

The development of cardiovascular dysfunction and shock in patients with invasive Bacillus anthracis infection has a particularly poor prognosis. Growing evidence indicates that several bacterial components likely play important pathogenic roles in this injury. As with other pathogenic Gram-positive bacteria, the B. anthracis cell wall and its peptidoglycan constituent produce a robust inflammatory response with its attendant tissue injury, disseminated intravascular coagulation and shock. However, B. anthracis also produces lethal and edema toxins that both contribute to shock. Growing evidence suggests that lethal toxin, a metalloprotease, can interfere with endothelial barrier function as well as produce myocardial dysfunction. Edema toxin has potent adenyl cyclase activity and may alter endothelial function, as well as produce direct arterial and venous relaxation. Furthermore, both toxins can weaken host defense and promote infection. Finally, B. anthracis produces non-toxin metalloproteases which new studies show can contribute to tissue injury, coagulopathy and shock. In the future, an understanding of the individual pathogenic effects of these different components and their interactions will be important for improving the management of B. anthracis infection and shock.

Group A streptococcal necrotizing fasciitis in the emergency department.

BACKGROUND: Group A Streptococcal (GAS) necrotizing fasciitis is a critical emergency. Patients with necrotizing fasciitis principally present to emergency departments (EDs), but most studies are focused on hospitalized patients. OBJECTIVE: An ED patient-based retrospective study was conducted to investigate the clinical characteristics, associated factors, and outcomes of GAS necrotizing fasciitis in the ED. METHODS: Patients visiting the ED from January 2005 through December 2011 with the diagnosis of GAS necrotizing fasciitis were enrolled. All patients with the diagnosis of noninvasive skin and soft-tissue infections caused by GAS were included as the control group. RESULTS: During the study period, 75 patients with GAS necrotizing fasciitis were identified. Males accounted for 84% of patients. The most prevalent underlying disease was diabetes mellitus (45.3%). Bullae were recognized in 37.3% of patients. One third of cases were complicated by bacteremia. Polymicrobial infections were found in 30.7% of patients. Overall mortality rate for GAS necrotizing fasciitis was 16%. Patients aged >60 years with diabetes mellitus, liver cirrhosis, and gout were considerably more likely to have GAS necrotizing fasciitis than noninvasive infections. Patients presenting with bacteremia, shock, duration of symptoms/signs <5 days, low white blood cell count, low platelet count, and prolonged prothrombin time were associated with increased mortality. Surgery is a significantly negative factor for mortality of patients with GAS necrotizing fasciitis (odds ratio = 0.16; 95% confidence interval 0.002-0.16; p < 0.001). CONCLUSIONS: A better understanding of the associated factors and initiation of adequate treatments will allow for improved survival after GAS necrotizing fasciitis.

Protective antigen antibody augments hemodynamic support in anthrax lethal toxin shock in canines.

BACKGROUND: Anthrax-associated shock is closely linked to lethal toxin (LT) release and is highly lethal despite conventional hemodynamic support. We investigated whether protective antigen-directed monoclonal antibody (PA-mAb) treatment further augments titrated hemodynamic support. METHODS AND RESULTS: Forty sedated, mechanically ventilated, instrumented canines challenged with anthrax LT were assigned to no treatment (controls), hemodynamic support alone (protocol-titrated fluids and norepinephrine), PA-mAb alone (administered at start of LT infusion [0 hours] or 9 or 12 hours later), or both, and observed for 96 hours. Although all 8 controls died, 2 of 8 animals receiving hemodynamic support alone survived (median survival times 65 vs 85 hours, respectively; P = .03). PA-mAb alone at 0 hour improved survival (5 of 5 animals survived), but efficacy decreased progressively with delayed treatment (9 hours, 2 of 3 survived; 12 hours, 0 of 4 survived) (P = .004 comparing survival across treatment times). However, combined treatment increased survival irrespective of PA-mAb administration time (0 hours, 4 of 5 animals; 9 hours, 3 of 3 animals; and 12 hours, 4 of 5 animals survived) (P = .95 comparing treatment times). Compared to hemodynamic support alone, when combined over PA-mAb treatment times (0, 9, and 12 hours), combination therapy produced higher survival (P = .008), central venous pressures, and left ventricular ejection fractions, and lower heart rates, norepinephrine requirements and fluid retention (P ≤ .03). CONCLUSIONS: PA-mAb may augment conventional hemodynamic support during anthrax LT-associated shock.

The role of bradykinin and the effect of the bradykinin receptor antagonist icatibant in porcine sepsis.

Bradykinin (BK) is regarded as an important mediator of edema, shock, and inflammation during sepsis. In this study, we evaluated the contribution of BK in porcine sepsis by blocking BK and by measuring the stable BK metabolite, BK1-5, using anesthetized pigs. The effect of BK alone, the efficacy of icatibant to block this effect, and the recovery of BK measured as plasma BK1-5 were first investigated. Purified BK injected intravenously induced an abrupt fall in blood pressure, which was completely prevented by pretreatment with icatibant. BK1-5 was detected in plasma corresponding to the doses given. The effect of icatibant was then investigated in an established model of porcine gram-negative sepsis. Neisseria meningitidis was infused intravenously without any pretreatment (n = 8) or pretreated with icatibant (n = 8). Negative controls received saline only. Icatibant-treated pigs developed the same degree of severe sepsis as did the controls. Both groups had massive capillary leakage, leukopenia, and excessive cytokine release. The plasma level of BK1-5 was low or nondetectable in all pigs. The latter observation was confirmed in supplementary studies with pigs undergoing Escherichia coli or polymicrobial sepsis induced by cecal ligation and puncture. In conclusion, icatibant completely blocked the hemodynamic effects of BK but had no beneficial effects on N. meningitidis-induced edema, shock, and inflammation. This and the fact that plasma BK1-5 in all the septic pigs was virtually nondetectable question the role of BK as an important mediator of porcine sepsis. Thus, the data challenge the current view of the role of BK also in human sepsis.

Vulnerability of an equine pericardial roll graft to Gram-positive cocci after graft replacement for a ruptured infected abdominal aorta.

We describe the influence of methicillin-resistant Staphylococcus aureus (MRSA) bacteremia on histopathological alteration of a glutaraldehyde-fixed equine pericardial roll (EPR) graft in a 77-year-old male who underwent in-situ EPR replacement of a ruptured infected abdominal aorta with concomitant repair of the perforated duodenum. The patient died of circulatory failure after septic shock due to MRSA infection and gastrointestinal bleeding on postoperative day (POD) 23. The autopsy revealed no perforation of the EPR graft or anastomotic disruption between the native abdominal aorta and EPR graft. Histological examination revealed that the inner layer of the EPR graft was colonized and damaged by Gram-positive cocci (MRSA suspected). We therefore suggest that the infection-resistant property of EPR grafts may be uncertain in patients with postoperative sustained MRSA bacteremia when these grafts are used for arterial reconstruction.

Shock and tuberculous enteritis in a non-HIV infected healthy man.

We reported a case of shock, diarrhea and tuberculous enteritis in a previously healthy 32-year-old non-HIV infected man. This case presented initially with acute profuse watery diarrhea. The bacterial and virus cultures were negative. Tuberculous enteritis was diagnosed by detecting Mycobacterium tuberculosis on stool culture 52 days after presentation. The symptoms resolved after treatment with intravenous fluids and corticosteroids but was treated with anti- tuberculous medication. Tuberculous enteritis should be included in the differential diagnosis of patients with enteritis and shock.

Palliative stent-graft insertion followed by an allograft replacement for an infected and ruptured aortic aneurysm.

We report a surgical case of infected thoracic aortic aneurysm. Before arrival of the cryopreserved aortic allograft, the patient had hemoptysis resulting from aneurysm rupture. Therefore endovascular stent grafting was urgently performed three days prior to in situ allograft implantation. Palliative stent grafting prevented circulatory collapse and stabilized the patient until successful allograft implantation.

Community-acquired bacterial meningitis in elderly patients: experience over 30 years.

Clinical characteristics, etiologies, evolution, and prognostic factors of community-acquired bacterial meningitis in elderly patients are not well known. To improve this knowledge, all episodes of community-acquired bacterial meningitis were prospectively recorded and cases occurring in patients >or=65 years old were selected. During the period 1977-2006, 675 episodes in adults (aged >or=18 yr) were recorded, with 185 (27%) in patients aged >or=65 years old; 76 were male and 109 were female, with a mean age of 73 +/- 6 years (range, 65-93 yr). Causative microorganisms were Streptococcus pneumoniae 74, Neisseria meningitidis 49, Listeria monocytogenes 17, other streptococcal 9, Escherichia coli 6, Haemophilus influenzae 4, Klebsiella pneumoniae and Staphylococcus aureus 2 each, Capnocytophaga canimorsus and Enterococcus faecalis 1 each, and unknown in 20. On admission 91% had had fever, 32% were in a coma (Glasgow Coma Scale or=65 yr), who showed a higher frequency of diabetes and malignancy as underlying disease; pneumonia, otitis, and pericranial fistula as predisposing factors; and S. pneumoniae and L. monocytogenes as etiology. There were also differences in clinical presentation, complications, sequelae, and mortality. Factors independently related with mortality were age, pneumonia as a predisposing factor, coma on admission, and heart failure and seizures after therapy. Dexamethasone therapy was a protective factor. In conclusion, bacterial meningitis in elderly patients is associated with greater diagnostic difficulties and neurologic severity and more complications, as well as with increased mortality. Antiseizure prophylaxis might be useful in these patients.

Radiologic progression of pulmonary infiltrates predicts a worse prognosis in severe community-acquired pneumonia than bacteremia.

BACKGROUND: It remains unknown whether bacteremia and rapid radiologic progression of pulmonary infiltrates increase the risk of shock and mortality in ICU patients with community-acquired pneumonia (CAP). The objective of this study was to investigate the relative importance of these two factors in the outcome of patients with severe CAP (sCAP). METHODS: A secondary analysis in a multicenter observational study was conducted in 457 patients with CAP admitted to the ICU. Patients were classified into four groups: group RB, rapid radiographic spread of pulmonary infiltrates and bacteremia (n = 48); group R, rapid radiographic spread but no bacteremia (n = 183); group B, bacteremia but without rapid radiographic spread (n = 39); and group C, neither rapid radiographic spread nor bacteremia (n = 187). RESULTS: Logistic regression analysis showed that group RB and group R had a greater risk for shock than group C (adjusted odds ratio [aOR], 8.9; 95% confidence interval [CI], 4.0 to 19.7; and aOR, 3.8; 95% CI, 2.5 to 5.9; respectively), while patients in group B had no increased risk. In addition, compared to group C, group RB and group R had an increased risk of ICU death (aOR, 3.4; 95% CI, 1.4 to 8.1; and aOR, 3.1; 95% CI, 1.7 to 5.7, respectively), while patients in group B had none. CONCLUSIONS: In this cohort of patients with severe CAP, radiologic progression of pulmonary infiltrates in the first 48 h is a significant adverse prognostic feature. In contrast, bacteremia does not affect outcomes.