Treatment of Human Plague: A Systematic Review of Published Aggregate Data on Antimicrobial Efficacy, 1939-2019

Interaction between Yersinia pestis Ail Outer Membrane Protein and the C-Terminal Domain of Human Vitronectin

Yersinia pestis, the causative agent of plague, is capable of evading the human immune system response by recruiting the plasma circulating vitronectin proteins, which act as a shield and avoid its lysis. Vitronectin recruitment is mediated by its interaction with the bacterial transmembrane protein Ail, protruding from the Y. pestis outer membrane. By using all-atom long-scale molecular dynamic simulations of Ail embedded in a realistic model of the bacterial membrane, we have shown that vitronectin forms a stable complex, mediated by interactions between the disordered moieties of the two proteins. The main amino acids driving the complexation have also been evidenced, thus favoring the possible rational design of specific peptides which, by inhibiting vitronectin recruitment, could act as original antibacterial agents.

A systematic review of the clinical profile of patients with bubonic plague and the outcome measures used in research settings

BACKGROUND

Plague is a zoonotic disease that, despite affecting humans for more than 5000 years, has historically been the subject of limited drug development activity. Drugs that are currently recommended in treatment guidelines have been approved based on animal studies alone-no pivotal clinical trials in humans have yet been completed. As a result of the sparse clinical research attention received, there are a number of methodological challenges that need to be addressed in order to facilitate the collection of clinical trial data that can meaningfully inform clinicians and policy-makers. One such challenge is the identification of clinically-relevant endpoints, which are informed by understanding the clinical characterisation of the disease-how it presents and evolves over time, and important patient outcomes, and how these can be modified by treatment.

METHODOLOGY/PRINCIPAL FINDINGS

This systematic review aims to summarise the clinical profile of 1343 patients with bubonic plague described in 87 publications, identified by searching bibliographic databases for studies that meet pre-defined eligibility criteria. The majority of studies were individual case reports. A diverse group of signs and symptoms were reported at baseline and post-baseline timepoints-the most common of which was presence of a bubo, for which limited descriptive and longitudinal information was available. Death occurred in 15% of patients; although this varied from an average 10% in high-income countries to an average 17% in low- and middle-income countries. The median time to death was 1 day, ranging from 0 to 16 days.

CONCLUSIONS/SIGNIFICANCE

This systematic review elucidates the restrictions that limited disease characterisation places on clinical trials for infectious diseases such as plague, which not only impacts the definition of trial endpoints but has the knock-on effect of challenging the interpretation of a trial's results. For this reason and despite interventional trials for plague having taken place, questions around optimal treatment for plague persist.

Polyclonal Antibodies Derived from Transchromosomic Bovines Vaccinated with the Recombinant F1-V Vaccine Increase Bacterial Opsonization In Vitro and Protect Mice from Pneumonic Plague

Plague is an ancient disease that continues to be of concern to both the public health and biodefense research communities. Pneumonic plague is caused by hematogenous spread of Yersinia pestis bacteria from a ruptured bubo to the lungs or by directly inhaling aerosolized bacteria. The fatality rate associated with pneumonic plague is significant unless effective antibiotic therapy is initiated soon after an early and accurate diagnosis is made. As with all bacterial pathogens, drug resistance is a primary concern when developing strategies to combat these Yersinia pestis infections in the future. While there has been significant progress in vaccine development, no FDA-approved vaccine strategy exists; thus, other medical countermeasures are needed. Antibody treatment has been shown to be effective in animal models of plague. We produced fully human polyclonal antibodies in transchromosomic bovines vaccinated with the recombinant F1-V plague vaccine. The resulting human antibodies opsonized Y. pestis bacteria in the presence of RAW264.7 cells and afforded significant protection to BALB/c mice after exposure to aerosolized Y. pestis. These data demonstrate the utility of this technology to produce large quantities of non-immunogenic anti-plague human antibodies to prevent or possibly treat pneumonic plague in human.

Opportunistic etiological agents causing lung infections: emerging need to transform lung-targeted delivery

Lung diseases continue to draw considerable attention from biomedical and public health care agencies. The lung with the largest epithelial surface area is continuously exposed to the external environment during exchanging gas. Therefore, the chances of respiratory disorders and lung infections are overgrowing. This review has covered promising and opportunistic etiologic agents responsible for lung infections. These pathogens infect the lungs either directly or indirectly. However, it is difficult to intervene in lung diseases using available oral or parenteral antimicrobial formulations. Many pieces of research have been done in the last two decades to improve inhalable antimicrobial formulations. However, very few have been approved for human use. This review article discusses the approved inhalable antimicrobial agents (AMAs) and identifies why pulmonary delivery is explored. Additionally, the basic anatomy of the respiratory system linked with barriers to AMA delivery has been discussed here. This review opens several new scopes for researchers to work on pulmonary medicines for specific diseases and bring more respiratory medication to market.

Spray-Dried Inhalable Powder Formulations of Gentamicin Designed for Pneumonic Plague Therapy in a Mouse Model

Infection with Yersinia pestis (Y. pestis) may cause pneumonic plague, which is inevitably fatal without treatment. Gentamicin (GM), an aminoglycoside antibiotic, is a drug commonly used in the treatment of plague. However, it requires repeated intramuscular or intravenous administration. Pulmonary drug delivery is noninvasive, with the advantages of local targeting and reduced risk of systemic toxicity. In this study, GM powders were prepared using spray-drying technology. The powders displayed good physical and chemical properties and met the requirements for human pulmonary inhalation. The formulation of the powders was optimized using a 3² full factorial design. A formulation of 15% (w/w) of L-leucine was prepared, and the spray-drying process parameters using an inlet temperature of 120°C and a 15% pump rate were determined to produce the best powder. In addition, the optimized GM spray-dried powders were characterized in terms of morphology, crystallinity, powder fluidity, and aerodynamic particle size distribution analysis. In a mouse model of pneumonic plague, we compared the therapeutic effects among three administration routes, including subcutaneous injection, liquid atomization, and dry powder atomization. In conclusion, our data suggest that inhalation therapy with GM spray-dried powders is an effective treatment for pneumonic plague.

Silatrane-Sulfonamide Hybrids as Promising Antibacterial Agents

At the A. E. Favorsky Irkutsk Institute of Chemistry, a series of silatrane-sulfonamide hybrids 1a-d and 2a-d was synthesized. The antibacterial activity of 1a, 1b, 1d, 2a, and 2b against test strains of bacteria Yersinia pestis EV NIIEG, Yersinia enterocolitica 628/1, Listeria monocytogenes 766, and Starhylococcus aureus ATCC 6538-P (FDA 209-Р) was evaluated. The minimum inhibitory concentration for silatrane-sulfonamide hybrids was 100-200 mg/liter. Silatrane-sulfonamide hybrid 1d was the most active against all tested strains: minimum inhibitory concentration 100 mg/liter. Exposure to silatrane-sulfonamide hybrids in a doses of 100-200 mg/liter inhibited culture growth by 50-75%.

Plague Prevention and Therapy: Perspectives on Current and Future Strategies

Plague, caused by the bacterial pathogen Yersinia pestis, is a vector-borne disease that has caused millions of human deaths over several centuries. Presently, human plague infections continue throughout the world. Transmission from one host to another relies mainly on infected flea bites, which can cause enlarged lymph nodes called buboes, followed by septicemic dissemination of the pathogen. Additionally, droplet inhalation after close contact with infected mammals can result in primary pneumonic plague. Here, we review research advances in the areas of vaccines and therapeutics for plague in context of Y. pestis virulence factors and disease pathogenesis. Plague continues to be both a public health threat and a biodefense concern and we highlight research that is important for infection mitigation and disease treatment.

Antibiotic Resistance Genes in Lemur Gut and Soil Microbiota Along a Gradient of Anthropogenic Disturbance

The overuse of man-made antibiotics has facilitated the global propagation of antibiotic resistance genes in animals, across natural and anthropogenically disturbed environments. Although antibiotic treatment is the most well-studied route by which resistance genes can develop and spread within host-associated microbiota, resistomes also can be acquired or enriched via more indirect routes, such as via transmission between hosts or via contact with antibiotic-contaminated matter within the environment. Relatively little is known about the impacts of anthropogenic disturbance on reservoirs of resistance genes in wildlife and their environments. We therefore tested for (a) antibiotic resistance genes in primate hosts experiencing different severities and types of anthropogenic disturbance (i.e., non-wildlife animal presence, human presence, direct human contact, and antibiotic treatment), and (b) covariation between host-associated and environmental resistomes. We used shotgun metagenomic sequencing of ring-tailed lemur (Lemur catta) gut resistomes and associated soil resistomes sampled from up to 10 sites: seven in the wilderness of Madagascar and three in captivity in Madagascar or the United States. We found that, compared to wild lemurs, captive lemurs harbored greater abundances of resistance genes, but not necessarily more diverse resistomes. Abundances of resistance genes were positively correlated with our assessments of anthropogenic disturbance, a pattern that was robust across all ten lemur populations. The composition of lemur resistomes was site-specific and the types of resistance genes reflected antibiotic usage in the country of origin, such as vancomycin use in Madagascar. We found support for multiple routes of ARG enrichment (e.g., via human contact, antibiotic treatment, and environmental acquisition) that differed across lemur populations, but could result in similar degrees of enrichment. Soil resistomes varied across natural habitats in Madagascar and, at sites with greater anthropogenic disturbance, lemurs and soil resistomes covaried. As one of the broadest, single-species investigations of wildlife resistomes to date, we show that the transmission and enrichment of antibiotic resistance genes varies across environments, thereby adding to the mounting evidence that the resistance crisis extends outside of traditional clinical settings.

Antimicrobial Treatment and Prophylaxis of Plague: Recommendations for Naturally Acquired Infections and Bioterrorism Response

This report provides CDC recommendations to U.S. health care providers regarding treatment, pre-exposure prophylaxis, and postexposure prophylaxis of plague. Yersinia pestis, the bacterium that causes plague, leads to naturally occurring disease in the United States and other regions worldwide and is recognized as a potential bioterrorism weapon. A bioweapon attack with Y. pestis could potentially infect thousands, requiring rapid and informed decision making by clinicians and public health agencies. The U.S. government stockpiles a variety of medical countermeasures to mitigate the effects of a bioterrorism attack (e.g., antimicrobials, antitoxins, and vaccines) for which the 21st Century Cures Act mandates the development of evidence-based guidelines on appropriate use. Guidelines for treatment and postexposure prophylaxis of plague were published in 2000 by a nongovernmental work group; since then, new human clinical data, animal study data, and U.S. Food and Drug Administration approvals of additional countermeasures have become available. To develop a comprehensive set of updated guidelines, CDC conducted a series of systematic literature reviews on human treatment of plague and other relevant topics to collect a broad evidence base for the recommendations in this report. Evidence from CDC reviews and additional sources were presented to subject matter experts during a series of forums. CDC considered individual expert input while developing these guidelines, which provide recommended best practices for treatment and prophylaxis of human plague for both naturally occurring disease and following a bioterrorism attack. The guidelines do not include information on diagnostic testing, triage decisions, or logistics involved in dispensing medical countermeasures. Clinicians and public health officials can use these guidelines to prepare their organizations, hospitals, and communities to respond to a plague mass-casualty event and as a guide for treating patients affected by plague.

Antibiotic Therapy of Plague: A Review

Plague-a deadly disease caused by the bacterium Yersinia pestis-is still an international public health concern. There are three main clinical forms: bubonic plague, septicemic plague, and pulmonary plague. In all three forms, the symptoms appear suddenly and progress very rapidly. Early antibiotic therapy is essential for countering the disease. Several classes of antibiotics (e.g., tetracyclines, fluoroquinolones, aminoglycosides, sulfonamides, chloramphenicol, rifamycin, and β-lactams) are active in vitro against the majority of Y. pestis strains and have demonstrated efficacy in various animal models. However, some discrepancies have been reported. Hence, health authorities have approved and recommended several drugs for prophylactic or curative use. Only monotherapy is currently recommended; combination therapy has not shown any benefits in preclinical studies or case reports. Concerns about the emergence of multidrug-resistant strains of Y. pestis have led to the development of new classes of antibiotics and other therapeutics (e.g., LpxC inhibitors, cationic peptides, antivirulence drugs, predatory bacteria, phages, immunotherapy, host-directed therapy, and nutritional immunity). It is difficult to know which of the currently available treatments or therapeutics in development will be most effective for a given form of plague. This is due to the lack of standardization in preclinical studies, conflicting data from case reports, and the small number of clinical trials performed to date.

Plague: Still a Threat, but Evidence and Preparedness Are Keys to Fighting Back

Yersinia pestis continues to cause naturally occurring outbreaks in certain regions worldwide and is a potential bioterrorism agent. This supplement presents new data on plague to advance current knowledge and inform new clinical guidelines for treatment and prophylaxis.

History of the Plague: An Ancient Pandemic for the Age of COVID-19

During the fourteenth century, the bubonic plague or Black Death killed more than one third of Europe or 25 million people. Those afflicted died quickly and horribly from an unseen menace, spiking high fevers with suppurative buboes (swellings). Its causative agent is Yersinia pestis, creating recurrent plague cycles from the Bronze Age into modern-day California and Mongolia. Plague remains endemic in Madagascar, Congo, and Peru. This history of medicine review highlights plague events across the centuries. Transmission is by fleas carried on rats, although new theories include via human body lice and infected grain. We discuss symptomatology and treatment options. Pneumonic plague can be weaponized for bioterrorism, highlighting the importance of understanding its clinical syndromes. Carriers of recessive familial Mediterranean fever (FMF) mutations have natural immunity against Y. pestis. During the Black Death, Jews were blamed for the bubonic plague, perhaps because Jews carried FMF mutations and died at lower plague rates than Christians. Blaming minorities for epidemics echoes across history into our current coronavirus pandemic and provides insightful lessons for managing and improving its outcomes.