Daniel S. Chertow

Ebola Virus Disease in West Africa — Clinical Manifestations and Management

The cumulative clinical observations of physicians who cared for more than 700 patients with Ebola virus disease in Liberia between August and October of this year support a rational approach to EVD management in resource-limited settings.

Bacterial Coinfection in Influenza: A Grand Rounds Review

Bacterial coinfection complicated nearly all influenza deaths in the 1918 influenza pandemic and up to 34% of 2009 pandemic influenza A(H1N1) infections managed in intensive care units worldwide. More than 65,000 deaths attributable to influenza and pneumonia occur annually in the United States. Data from 683 critically ill patients with 2009 pandemic influenza A(H1N1) infection admitted to 35 intensive care units in the United States reveal that bacterial coinfection commonly occurs within the first 6 days of influenza infection, presents similarly to influenza infection occurring alone, and is associated with an increased risk of death. Pathogens that colonize the nasopharynx, including Staphylococcus aureus, Streptococcus pneumoniae, and Streptococcus pyogenes, are most commonly isolated. Complex viral, bacterial, and host factors contribute to the pathogenesis of coinfection. Reductions in morbidity and mortality are dependent on prevention with available vaccines as well as early diagnosis and treatment.

Lethal Synergism of 2009 Pandemic H1N1 Influenza Virus and Streptococcus pneumoniae Coinfection Is Associated with Loss of Murine Lung Repair Responses

ABSTRACT Secondary bacterial infections increase disease severity of influenza virus infections and contribute greatly to increased morbidity and mortality during pandemics. To study secondary bacterial infection following influenza virus infection, mice were inoculated with sublethal doses of 2009 seasonal H1N1 virus (NIH50) or pandemic H1N1 virus (Mex09) followed by inoculation with Streptococcus pneumoniae 48 h later. Disease was characterized by assessment of weight loss and survival, titration of virus and bacteria by quantitative reverse transcription-PCR (qRT-PCR), histopathology, expression microarray, and immunohistochemistry. Mice inoculated with virus alone showed 100% survival for all groups. Mice inoculated with Mex09 plus S. pneumoniae showed severe weight loss and 100% mortality with severe alveolitis, denuded bronchiolar epithelium, and widespread expression of apoptosis marker cleaved caspase 3. In contrast, mice inoculated with NIH50 plus S. pneumoniae showed increased weight loss, 100% survival, and slightly enhanced lung pathology. Mex09-S. pneumoniae coinfection also resulted in increased S. pneumoniae replication in lung and bacteremia late in infection. Global gene expression profiling revealed that Mex09-S. pneumoniae coinfection did not induce significantly more severe inflammatory responses but featured significant loss of epithelial cell reproliferation and repair responses. Histopathological examination for cell proliferation marker MCM7 showed significant staining of airway epithelial cells in all groups except Mex09-S. pneumoniae-infected mice. This study demonstrates that secondary bacterial infection during 2009 H1N1 pandemic virus infection resulted in more severe disease and loss of lung repair responses than did seasonal influenza viral and bacterial coinfection. Moreover, this study provides novel insights into influenza virus and bacterial coinfection by showing correlation of lethal outcome with loss of airway basal epithelial cells and associated lung repair responses. IMPORTANCE Secondary bacterial pneumonias lead to increased disease severity and have resulted in a significant percentage of deaths during influenza pandemics. To understand the biological basis for the interaction of bacterial and viral infections, mice were infected with sublethal doses of 2009 seasonal H1N1 and pandemic H1N1 viruses followed by infection with Streptococcus pneumoniae 48 h later. Only infection with 2009 pandemic H1N1 virus and S. pneumoniae resulted in severe disease with a 100% fatality rate. Analysis of the host response to infection during lethal coinfection showed a significant loss of responses associated with lung repair that was not observed in any of the other experimental groups. This group of mice also showed enhanced bacterial replication in the lung. This study reveals that the extent of lung damage during viral infection influences the severity of secondary bacterial infections and may help explain some differences in mortality during influenza pandemics. Secondary bacterial pneumonias lead to increased disease severity and have resulted in a significant percentage of deaths during influenza pandemics. To understand the biological basis for the interaction of bacterial and viral infections, mice were infected with sublethal doses of 2009 seasonal H1N1 and pandemic H1N1 viruses followed by infection with Streptococcus pneumoniae 48 h later. Only infection with 2009 pandemic H1N1 virus and S. pneumoniae resulted in severe disease with a 100% fatality rate. Analysis of the host response to infection during lethal coinfection showed a significant loss of responses associated with lung repair that was not observed in any of the other experimental groups. This group of mice also showed enhanced bacterial replication in the lung. This study reveals that the extent of lung damage during viral infection influences the severity of secondary bacterial infections and may help explain some differences in mortality during influenza pandemics.

Autopsy series of 68 cases dying before and during the 1918 influenza pandemic peak

The 1918 to 1919 “Spanish” influenza pandemic virus killed up to 50 million people. We report here clinical, pathological, bacteriological, and virological findings in 68 fatal American influenza/pneumonia military patients dying between May and October of 1918, a period that includes ∼4 mo before the 1918 pandemic was recognized, and 2 mo (September–October 1918) during which it appeared and peaked. The lung tissues of 37 of these cases were positive for influenza viral antigens or viral RNA, including four from the prepandemic period (May–August). The prepandemic and pandemic peak cases were indistinguishable clinically and pathologically. All 68 cases had histological evidence of bacterial pneumonia, and 94% showed abundant bacteria on Gram stain. Sequence analysis of the viral hemagglutinin receptor-binding domain performed on RNA from 13 cases suggested a trend from a more “avian-like” viral receptor specificity with G222 in prepandemic cases to a more “human-like” specificity associated with D222 in pandemic peak cases. Viral antigen distribution in the respiratory tree, however, was not apparently different between prepandemic and pandemic peak cases, or between infections with viruses bearing different receptor-binding polymorphisms. The 1918 pandemic virus was circulating for at least 4 mo in the United States before it was recognized epidemiologically in September 1918. The causes of the unusually high mortality in the 1918 pandemic were not explained by the pathological and virological parameters examined. These findings have important implications for understanding the origins and evolution of pandemic influenza viruses.

MultiDrug-Resistant 2009 Pandemic Influenza A(H1N1) Viruses Maintain Fitness and Transmissibility in Ferrets

BACKGROUND The 2009 influenza A(H1N1) pandemic called attention to the limited influenza treatment options available, especially in individuals at high risk of severe disease. Neuraminidase inhibitor-resistant seasonal H1N1 viruses have demonstrated the ability to transmit well despite early data indicating that resistance reduces viral fitness. 2009 H1N1 pandemic viruses have sporadically appeared containing resistance to neuraminidase inhibitors and the adamantanes, but the ability of these viruses to replicate, transmit, and cause disease in mammalian hosts has not been fully characterized. METHODS Two pretreatment wild-type viruses and 2 posttreatment multidrug-resistant viruses containing the neuraminidase H275Y mutation collected from immunocompromised patients infected with pandemic influenza H1N1 were tested for viral fitness, pathogenicity, and transmissibility in ferrets. RESULTS The pretreatment wild-type viruses and posttreatment resistant viruses containing the H275Y mutation all demonstrated significant pathogenicity and equivalent viral fitness and transmissibility. CONCLUSIONS The admantane-resistant 2009 pandemic influenza A(H1N1) virus can develop the H275Y change in the neuraminidase gene conferring resistance to both oseltamivir and peramivir without any loss in fitness, transmissibility, or pathogenicity. This suggests that the dissemination of widespread multidrug resistance similar to neuraminidase inhibitor resistance in seasonal H1N1 is a significant threat.

Preparing for Critical Care Services to Patients With Ebola

As the current Zaire ebolavirus epidemic advances, infected patients may present or be transferred to medical settings with advanced management capabilities. Critical care units that may receive such patients must prepare to render such care while protecting staff from infection. Although providing supportive care to a critically ill patient with Ebola involves a pathogen more immediately lethal than others previously encountered in the United States, the risk to health care workers is manageable with infection prevention and control measures recommended by the Centers for Disease Control and Prevention (CDC) (1). We summarize the risks and protective measures included in preparation at the National Institutes of Health (NIH) and the experience gained in the clinical care of patients at Emory University hospital. The factors that increase the risk of caring for critically ill patients with Ebola include the low infectious dose of Ebola (1 to 10 viral particles) (2), the high quantity of virus shed in the large volume of body fluids produced during illness (3), the close and extended patient contact time required of providers, the need for invasive procedures, and the absence of proven effective therapeutics. Although compliance with infection control practices in hospitals has improved, it remains below 100% (4). The margin of error for infection is low for Ebola and the consequence of nonadherence to infection control practices potentially dire for providers and other patients. Medical facilities caring for these patients must establish and enforce fastidious infection control practices and must maintain a high level of staffing, all of whom must stringently adhere to these measures. The appropriate level of personal protective equipment (PPE) required to safely care for patients with Ebola is a topic of debate (5, 6). Some organizations have adopted very stringent measures that exceed the recommendations of the CDC, such as those used in U.S. biosafety level-4 laboratories. These measures include covering 100% of the skin and disinfecting PPE before removal (7). Health care facilities need to address on an individual basis whether a level of protection over and above the CDCs recommendations enhances staff safety or increases staff and community confidence that the risk for nosocomial transmission is being minimized. Preparing critical care units for patients with Ebola introduces serious challenges. These patients frequently require invasive interventions that involve specialized equipment and mandate technical proficiency. Performing such tasks in full PPE can be difficult due to altered sensory input, diminished dexterity, and greater fatigability. Careful planning and training may mitigate these circumstances. Preintervention planning of equipment needs and how the equipment will be decontaminated requires special attention. Critical care is a team sport. Effective preparation for the possibility of caring for a critically ill patient with Ebola requires the development of a multidisciplinary team that includes hospital administrators, infectious diseases specialists, hospital epidemiology, occupational medicine providers, biosafety managers, nurses, critical care physicians, respiratory therapists, laboratory staff, and housekeeping. The NIH multidisciplinary team reviewed the personnel required to provide critical carelevel support for a seriously ill patient with Ebola for 1 week and derived the following minimum staffing numbers for nurses and physicians: 2 nurses per 8-hour shift (6 per day, or 12 full-time employees), 1 to 2 physicians per shift (3 to 4 per day, or 6 full-time employees), and 1 PPE adherence monitor (called the Watsan, 3 per day, or 6 full-time employees). Additional staff needs include respiratory therapists; isolation adherence monitors; cohorted laboratory and housekeeping personnel; and administrative staff to manage logistics, supplies, waste, and public relations. Devoting such resources to patients with Ebola is likely to affect the institutions ability to staff other services. Institutions should also determine ahead of time whether they will require staff to care for patients with Ebola or if they will rely on health care providers who volunteer (we chose volunteers). Institutions should develop standard operating procedures for anticipated clinical interventions that maximize staff and patient safety. It is prudent to prestage equipment and supplies within the footprint of clinical space and plan for appropriate decontamination of these materials. Interventions for which standard operating procedures should be developed include performance of invasive procedures, such as intravenous line insertion and endotracheal intubation, code blue response, setup and use of mechanical ventilation, setup and use of renal replacement therapy, evacuation of an incapacitated or unconscious provider, and immediate occupational exposure management in a special isolation unit. Detailed standard operating procedures facilitate provision of high-quality critical care while maximizing safety. Although each U.S. health care facility must define and implement its own processes for Ebola preparedness, we hope that our experience may help inform this planning. We have found the following 4 measures helpful: First, staff education is vital to demystifying Ebola and reducing anxiety. Second, posters clarifying PPE donning and doffing procedures facilitate staff understanding and compliance. Third, an ongoing, coordinated multidisciplinary effort is required to establish standard operating procedures and staff must be trained to follow them. And finally, direct observation of clinical care enforces adherence to these procedures. Significant institutional investment in supplies, equipment, and staff is required. Advanced planning is needed to obtain and stage supplies and equipment, including point-of-care testing devices. Careful planning for removal of large amounts of solid waste is required and should involve early engagement of outside commercial waste disposal vendors. Facility modifications directed toward biosafety and security include geographic or barrier separation of the Ebola care unit from other units, heightened security and other provisions for restricted staff entry, and on-site or local autoclave access. The Table provides a framework for approaching the provision of critical care services to patients with Ebola. Table. Key Points for Institutions Preparing for Providing Critical Care to Patients With Ebola Given the unprecedented number of cases of infection in this outbreak and the escalating global response in West Africa, that U.S. health care facilities may be faced with critically ill patients with Ebola cannot be dismissed. Adequate planning and training across U.S. health care facilities is essential. There is real hope that advanced critical care will increase patient survival and that lessons learned through providing this care will enhance patient management and improve outcomes in more resource-limited settings. The time to make such preparations is now.

The Pathogenesis of Ebola Virus Disease.

For almost 50 years, ebolaviruses and related filoviruses have been repeatedly reemerging across the vast equatorial belt of the African continent to cause epidemics of highly fatal hemorrhagic fever. The 2013-2015 West African epidemic, by far the most geographically extensive, most fatal, and longest lasting epidemic in Ebolas history, presented an enormous international public health challenge, but it also provided insights into Ebolas pathogenesis and natural history, clinical expression, treatment, prevention, and control. Growing understanding of ebolavirus pathogenetic mechanisms and important new clinical observations of the disease course provide fresh clues about prevention and treatment approaches. Although viral cytopathology and immune-mediated cell damage in ebolavirus disease often result in severe compromise of multiple organs, tissue repair and organ function recovery can be expected if patients receive supportive care with fluids and electrolytes; maintenance of oxygenation and tissue perfusion; and respiratory, renal, and cardiovascular support. Major challenges for managing future Ebola epidemics include establishment of early and aggressive epidemic control and earlier and better patient care and treatment in remote, resource-poor areas where Ebola typically reemerges. In addition, it will be important to further develop Ebola vaccines and to adopt policies for their use in epidemic and pre-epidemic situations.

Loperamide Therapy for Voluminous Diarrhea in Ebola Virus Disease

The number of cases of Ebola virus disease (EVD) in West Africa has surpassed 19 000 [1]. Efforts to identify, isolate, and provide medical care to patients with EVD are ongoing, and efforts to improve clinical care must focus on improved management of massive gastrointestinal fluid loss. Gastrointestinal fluid losses, largely through diarrhea, are a hallmark manifestation of EVD that contribute to hypovolemic shock, severe electrolyte abnormalities, and high mortality [2, 3]. In contrast to cholera toxin–mediated diarrheal losses, in which oral rehydration solution alone dramatically reduces mortality [4], oral rehydration for patients with EVD is often insufficient to accomplish resuscitation or repletion of ongoing fluid losses. However, EVD is a systemic viral illness with profound and debilitating manifestations, including high fever, asthenia, myalgia, and delirium, that limit self-directed oral rehydration. New strategies are needed to limit mortality related to cholera-like gastrointestinal fluid losses in EVD. Massive gastrointestinal fluid and electrolyte losses may be successfully managed in resource-rich settings through careful estimation of volume losses, close laboratory monitoring of electrolytes and organ function, and replacement of fluid losses through balanced intravenous infusions over the course of illness [3]. This same level of intensive monitoring and care cannot be achieved in most EVD treatment units in West Africa, where high case loads, staffing shortages, and limited time in personal protective equipment because of the risk of heat exposure prohibit extended patient care interactions. In this setting, administration of antidiarrheal agents to limit gastrointestinal fluid and electrolyte losses may provide “a solution that prevents the problem at its source”. However, use of antidiarrheal agents for the management of EVD-mediated diarrhea is infrequently reported, and no safety and efficacy data to guide use in EVD exist. Although the mechanism of EVD-mediated diarrhea has not yet been characterized, the large volume of watery stool suggests a secretory process. Tolerance of enteral feeding when gastrointestinal symptoms are adequately controlled suggests that the small intestine structure and function remain intact. Autopsy studies of patients with EVD who died show mild inflammation of small intestinal lamina propria, suggesting the possibility of an inflammatory component to a secretory form of diarrhea, as well [5]. Clinically significant gastrointestinal bleeding observed in a small subset of patients with EVD, estimated to be <5% [2], raises the possibility that gastrointestinal inflammation may contribute to disease pathogenesis. Loperamide is a potent antidiarrheal agent with antiperistaltic and antisecretory effects [6]. Reducing EVD diarrheal losses with loperamide might allow for correction of negative fluid balance, reduce hypovolemic shock, limit electrolyte losses, and consequently improve survival. Recently, one author (D. S. C.) and colleagues reported that oral antiemetics and antidiarrheal therapy improved symptoms and reduced gastrointestinal fluid loss and environmental contamination in patients with EVD [2]. The reduction in environmental contamination may also lower the risk of nosocomial transmission to healthcare personnel and other patients under evaluation. There are limited data on the use of loperamide for EVD-mediated diarrhea [2]. Reluctance to use loperamide for EVD-mediated diarrhea may be based on the perception that it is of no benefit for the secretory diarrhea observed in cholera or concern about the risk of toxic megacolon when used to treat some bacterial inflammatory causes of diarrhea, such as Clostridium difficile infection [7]. Animal and human studies of shigellosis in the 1960s and subsequent case reports of adverse events raised concern that antimotility drug use in patients with infectious diarrhea might contribute to a worse outcome [8]. However, multiple randomized, placebo-controlled, double-blinded trials of loperamide in combination with antibiotic therapy for management of infectious diarrhea in adults have demonstrated its safety and efficacy [9]. A meta-analysis of 13 clinical trials of loperamide use in children aged ≤12 years with infectious diarrhea and predominantly mild dehydration demonstrated a decrease in the duration and frequency of diarrhea [10]. Serious adverse events associated with loperamide use, including death, ileus, or lethargy, were reported only in children <3 years of age. The Food and Drug Administration does not recommend loperamide use in children <24 months of age, and use is contraindicated in patients with dysentery (ie, stool with mucus or blood), but it may be used in combination with antibiotic treatment [11]. Loperamide should not be given to patients with suspected or documented ileus or intestinal paresis. Use of loperamide in patients with EVD to control gastrointestinal fluid losses and reduce environmental contamination appears rational, based on existing clinical observations and the available published data. However, controlled clinical trials of loperamide treatment of diarrhea in patients with EVD, in combination with oral rehydration solution, to assess safety and efficacy in adults and children, including its possible impact upon improving survival, are urgently needed. Until strategies to improve management of gastrointestinal fluid and electrolyte losses are refined and widely implemented in the management of EVD in West Africa, the presently observed high case-fatality will persist.

Bacillus anthracis protease InhA regulates BslA-mediated adhesion in human endothelial cells.

To achieve widespread dissemination in the host, Bacillus anthracis cells regulate their attachment to host endothelium during infection. Previous studies identified BslA (Bacillus anthracisS‐layer Protein A), a virulence factor of B. anthracis, as necessary and sufficient for adhesion of vegetative cells to human endothelial cells. While some factors have been identified, bacteria‐specific contributions to BslA mediated adhesion remain unclear. Using the attenuated vaccine Sterne 7702 strain of B. anthracis, we tested the hypothesis that InhA (immune inhibitor A), a B. anthracis protease, regulates BslA levels affecting the bacterias ability to bind to endothelium. To test this, a combination of inhA mutant and complementation analysis in adhesion and invasion assays, Western blot and InhA inhibitor assays were employed. Results show InhA downregulates BslA activity reducing B. anthracis adhesion and invasion in human brain endothelial cells. BslA protein levels in ΔinhA bacteria were significantly higher than wild‐type and complemented strains showing InhA levels and BslA expression are inversely related. BslA was sensitive to purified InhA degradation in a concentration‐ and time‐dependent manner. Taken together these data support the role of InhA regulation of BslA‐mediated vegetative cell adhesion and invasion.

Validation of Normal Human Bronchial Epithelial Cells as a Model for Influenza A Infections in Human Distal Trachea

Primary normal human bronchial/tracheal epithelial (NHBE) cells, derived from the distal-most aspect of the trachea at the bifurcation, have been used for a number of studies in respiratory disease research. Differences between the source tissue and the differentiated primary cells may impact infection studies based on this model. Therefore, we examined how well-differentiated NHBE cells compared with their source tissue, the human distal trachea, as well as the ramifications of these differences on influenza A viral pathogenesis research using this model. We employed a histological analysis including morphological measurements, electron microscopy, multi-label immunofluorescence confocal microscopy, lectin histochemistry, and microarray expression analysis to compare differentiated NHBEs to human distal tracheal epithelium. Pseudostratified epithelial height, cell type variety and distribution varied significantly. Electron microscopy confirmed differences in cellular attachment and paracellular junctions. Influenza receptor lectin histochemistry revealed that α2,3 sialic acids were rarely present on the apical aspect of the differentiated NHBE cells, but were present in low numbers in the distal trachea. We bound fluorochrome bioconjugated virus to respiratory tissue and NHBE cells and infected NHBE cells with human influenza A viruses. Both indicated that the pattern of infection progression in these cells correlated with autopsy studies of fatal cases from the 2009 pandemic.