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The emergence of carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP) poses grave threats to human health. These strains increased dramatically in clinical settings in China in the past few years but not in other parts of the world. Four isogenic K. pneumoniae strains, including classical K. pneumoniae , carbapenem-resistant K. pneumoniae (CRKP), hypervirulent K. pneumoniae (hvKP) and CR-hvKP, were created and subjected to phenotypic characterization, competition assays, mouse sepsis model and rat colonization tests to investigate the mechanisms underlying the widespread nature of CR-hvKP in China. Acquisition of virulence plasmid led to reduced fitness and abolishment of colonization in the gastrointestinal tract, which may explain why hvKP is not clinically prevalent after its emergence for a long time. However, tigecycline treatment facilitated the colonization of hvKP and CR-hvKP and reduced the population of Lactobacillus spp. in animal gut microbiome. Feeding with Lactobacillus spp. could significantly reduce the colonization of hvKP and CR-hvKP in the animal gastrointestinal tract. Our data implied that the clinical use of tigecycline to treat carbapenem-resistant K. pneumoniae infections facilitated the high spread of CR-hvKP in clinical settings in China and demonstrated that Lactobacillus spp . was a potential candidate for anticolonization strategy against CR-hvKP.

The epidemiological features of the newly emerged carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-HvKP) and its potential threat to human health are currently unknown. In this study, a total of 784 bla KPC-2 -bearing CRKP strains collected from three hospitals located at different geographical locales in China during 2014-2017 were subjected to molecular typing, screening of virulence plasmid, string test and WGS (367/784 strains). The proportion of CRKP among all clinical K. pneumoniae strains increased sharply in China during 2014-2017. A large proportion (58%) of these CRKP strains were found to harbour a virulence-encoding plasmid, while only 13% of such strains exhibited a hypervirulent phenotype by string test and neutrophil assay. The lack of hypervirulent phenotype in virulent plasmid-bearing CRKP strains was found to be due to the mutation's presence on rmpA and rmpA2 genes, which rendered them non-functional, while some strains carrying wild type rmpA did not exhibit hypervirulent phenotype either suggesting that other factors might also contribute to the hypervirulence of CRKP. Phylogenetic and SNP analysis indicated that the transmission of these CRKP strains in China likely involved several major clones of ST11. Carriage of IncFII pSWU01-like, bla KPC-2 -bearing plasmid was found to be the major mechanism of carbapenem resistance in these CRKP strains. In conclusion, our data indicated that the prevalence of CRKP strains carrying the virulence plasmid has rapidly increased in China, while genetic markers were not correlated well with the hypervirulent phenotypes, which call for a better definition and screening for these truly hypervirulent CR-HvKP strains in clinical settings.

With the development of multidrug resistance in Salmonella spp. in recent years, ciprofloxacin, ceftriaxone, and azithromycin have become the principal antimicrobial agents used for the treatment of Salmonella infections. The underlying mechanisms of plasmid-mediated ciprofloxacin and ceftriaxone resistance have attracted extensive research interest, but not much is focused on azithromycin resistance in Salmonella . In this study, we investigated the genetic features of two conjugative plasmids and a non-transferable virulence plasmid that encode azithromycin resistance in food-borne Salmonella strains. We showed that the azithromycin resistance phenotype of these strains was conferred by erm(B) gene and/or the complete genetic structure IS 26-mph(A)-mrx-mphR- IS 6100. Comparative genetic analysis showed that these conjugative plasmids might originate from Escherichia coli and play a role in the rapid dissemination of azithromycin resistance in Salmonella . These conjugative plasmids may also serve as a reservoir of antimicrobial resistance (AMR) genes in Salmonella in which these AMR genes may be acquired by the virulence plasmids of Salmonella via genetic transposition events. Importantly, the formation of a novel macrolide-resistance and virulence-encoding plasmid, namely pS1380-118 kb, was observed in this study. This plasmid was found to exhibit transmission potential and pose a serious health threat as the extensive transmission of azithromycin resistant and virulent Salmonella strains would further compromise the effectiveness of treatment for salmonellosis. Further surveillance and research on the dissemination and evolution routes of pS1380-118kb-like plasmids in potential human pathogens of the family of Enterobacteriaceae are necessary.

The coronavirus disease 2019 (COVID-19) pandemic has resulted in millions of patients infected worldwide and indirectly affecting even more individuals through disruption of daily living. Long-term adverse outcomes have been reported with similar diseases from other coronaviruses, namely Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS). Emerging evidence suggests that COVID-19 adversely affects different systems in the human body. This review summarizes the current evidence on the short-term adverse health outcomes and assesses the risk of potential long-term adverse outcomes of COVID-19. Major adverse outcomes were found to affect different body systems: immune system (including but not limited to Guillain-Barré syndrome and paediatric inflammatory multisystem syndrome), respiratory system (lung fibrosis and pulmonary thromboembolism), cardiovascular system (cardiomyopathy and coagulopathy), neurological system (sensory dysfunction and stroke), as well as cutaneous and gastrointestinal manifestations, impaired hepatic and renal function. Mental health in patients with COVID-19 was also found to be adversely affected. The burden of caring for COVID-19 survivors is likely to be huge. Therefore, it is important for policy makers to develop comprehensive strategies in providing resources and capacity in the healthcare system. Future epidemiological studies are needed to further investigate the long-term impact on COVID-19 survivors.

A newly emerged coronavirus, SARS-CoV-2, caused severe pneumonia outbreaks in China in December 2019 and has since spread to various countries around the world. To trace the evolution route and probe the transmission dynamics of this virus, we performed phylodynamic analysis of 247 high quality genomic sequences available in the GISAID platform as of 5 March 2020. Among them, four genetic clusters, defined as super-spreaders (SSs), could be identified and were found to be responsible for the major outbreaks that subsequently occurred in various countries. SS1 was widely disseminated in Asia and the US, and mainly responsible for outbreaks in the states of Washington and California as well as South Korea, whereas SS4 contributed to the pandemic in Europe. Using the signature mutations of each SS as markers, we further analysed 1539 genome sequences reported after 29 February 2020 and found that 90% of these genomes belonged to SSs, with SS4 being the most dominant. The relative degree of contribution of each SS to the pandemic in different continents was also depicted. Identification of these super-spreaders greatly facilitates development of new strategies to control the transmission of SARS-CoV-2.

Two vaccines, 23-valent pneumococcal polysaccharide vaccine (PPSV23) and 13-valent pneumococcal conjugate vaccine (PCV13), are widely available for the prevention of pneumococcal disease in adults. However, it is unclear how cost-effective these pneumococcal vaccine choices are in the Hong Kong healthcare environment. We aimed to assess the cost-effectiveness of a sequential administration of PCV13 followed by PPSV23 compared to a single dose of PPSV23 vaccination for pneumococcal disease control in Hong Kong adults aged ≥65 years and individuals aged 20-64 years with immunocompromising and chronic conditions. A previously developed deterministic cohort sequential model was applied to compare the outcomes of two vaccination strategies from a societal perspective. Population-specific model input, including incidence, mortality, case-fatality, risk group distribution, vaccination costs, disease management, and productivity loss, was estimated from a Hong Kong-wide electronic medical database. Costs were valued in US$ in 2017. Vaccination strategies with an incremental cost-effectiveness ratio (ICER, defined as incremental cost per QALY saved) less than one local GDP per capita ($46,193 in 2017) were defined as highly cost-effective. Deterministic sensitivity analyses (SA) were conducted. Compared with single-dose PPSV23, sequential vaccination of PCV13 followed by PPSV23 was cost-saving for adults aged ≥20 years. In the deterministic SA, the base-case results were robust for tested parameter uncertainties. Future vaccination policies should consider the cost-effectiveness of a sequential vaccination strategy as a measure to reduce the vaccine-preventable pneumococcal disease burden in Hong Kong.

To investigate whether introduction of colistin into the clinical settings selected colistin-resistant CRE, we performed molecular epidemiological study of 1868 CRE strains collected from different geographical locales in China during the period 2014-2019. 1755 (96.18%) isolates carried the carbapenemase genes bla KPC and bla NDM ; 14 Escherichia coli isolates (0.75%) carrying mcr-1 and bla NDM (MCR-CREC) were also identified. Importantly, the number and relative prevalence of MCR-CREC isolates increased from 5 (0.41%) to 9 (1.38%) after introduction of polymyxin into clinical practice. Consistently, results of genetic analysis indicated that MCR-CREC strains collected before December 2017 were genetically diverse, yet those collected after that date exhibited more closely related genetic profiles, indicating that specific MCR-CREC strains were rapidly selected as a result of increased usage of colistin in clinical settings. The resistance level of MCR-CREC isolates to colistin increased after the introduction of polymyxin into clinical use with the MIC to colistin from <2 mg/L in 80% strains to 2 mg/L in 100% strains. Further dissemination of MCR-CREC strains, which exhibit resistance to the last-line drugs of carbapenems and colistin, is expected to pose a severe threat to human health.

Ciprofloxacin resistance in Salmonella has been increasingly reported due to the emergence and dissemination of multiple Plasmid-Mediated Quinolone Resistance (PMQR) determinants, which are mainly located in non-conjugative plasmids or chromosome. In this study, we aimed to depict the molecular mechanisms underlying the rare phenomenon of horizontal transfer of ciprofloxacin resistance phenotype in Salmonella by conjugation experiments, S1-PFGE and complete plasmid sequencing. Two types of non-conjugative plasmids, namely an IncX1 type carrying a qnrS1 gene, and an IncH1 plasmid carrying the oqxAB - qnrS gene, both ciprofloxacin resistance determinants in Salmonella , were recovered from two Salmonella strains. Importantly, these non-conjugative plasmids could be fused with a novel Incl1 type conjugative helper plasmid, which could target insertion sequence (IS) elements located in the non-conjugative, ciprofloxacin-resistance-encoding plasmid through replicative transcription, eventually forming a hybrid conjugative plasmid transmissible among members of Enterobacteriaceae . Since our data showed that such conjugative helper plasmids are commonly detectable among clinical Salmonella strains, particularly S. Typhimurium, fusion events leading to generation and enhanced dissemination of conjugative ciprofloxacin resistance-encoding plasmids in Salmonella are expected to result in a sharp increase in the incidence of resistance to fluoroquinolone, the key choice for treating life-threatening Salmonella infections, thereby posing a serious public health threat.

The recent convergence of genetic elements encoding phenotypic carbapenem-resistance and hypervirulence within a single Klebsiella pneumoniae host strain represents a major public concern. To obtain a better understanding of the genetic characteristic of this emerging 'superbug', the complete genomes of 3 isolates of ST11 carbapenemase-producing hypervirulent K. pneumoniae were generated using the Oxford nanopore MinION platform. Comparative whole-genome analysis identified 13 SNPs and 3 major regions of indels in the chromosomes of the clonally disseminated isolates. ISKpn18-mediated disruption in the mgrB gene, which was associated with colistin resistance, was identified in two later strains, leading to the emergence of hypervirulent K. pneumoniae that was simultaneously colistin- and carbapenem-resistant. Five plasmids were recovered from each isolate, including a 178 Kb IncHI1B/FIB-type rmpA2-bearing virulence plasmid, a 177.5 Kb IncFII/R self-transferable bla KPC-2 -bearing MDR plasmid, a 99.7 Kb Incl1 plasmid and two ColRNAI-type plasmids of sizes of 11.9 and 5.6 Kb, respectively. The presence of homologous regions between the non-conjugative virulence plasmid and conjugative bla KPC-2 -bearing MDR plasmid suggests that transmission of the virulence plasmid from ST23 K. pneumoniae to ST11 CRKP may be mediated by the co-integrated transfer of these two plasmids. Emergence of colistin-resistant and carbapenemase-producing hypervirulent K. pneumoniae strains further emphasizes the urgency for the establishment of a coordinated global program to eradicate hypervirulent and/or pan-drug-resistant strains of K. pneumoniae from clinical settings and the community.

Emergence of carbapenem-resistant Klebsiella pneumoniae (CRKP) strains that also exhibit resistance to tigecycline and colistin have become a major clinical concern, as these two agents are the last-resort antibiotics used for treatment of CRKP infections. A leukemia patient infected with CRKP was subjected to follow-up analysis of variation in phenotypic and genotypic characteristics of CRKP strains isolated from various specimens at different stages of treatment over a period of 3 years. Our data showed that (1) carbapenem treatment led to the emergence of CRKP in the gastrointestinal (GI) tract of the patient, which subsequently caused infections at other body sites as well as septicemia; (2) treatment with tigecycline led to the emergence of tigecycline-resistant CRKP, possibly through induction of the expression of a variant tet(A) gene located in a conjugative plasmid; (3) colistin treatment was effective in clearing CRKP from the bloodstream but led to the emergence of mcr-1-positive Enterobacteriaceae strains as well as colistin-resistant CRKP in the GI tract due to inactivation of the mgrB gene; and (4) tigecycline- and colistin-resistant CRKP could persist in the human GI tract for a prolonged period even without antibiotic selection pressure. In conclusion, clinical CRKP strains carrying a conjugative plasmid that harbors the bla KPC-2 and tet(A) variant genes readily evolve into tigecycline- and colistin-resistant CRKP upon treatment with these two antibiotics and persist in the human GI tract.

Objective: To determine the association between incident proton pump inhibitor (PPI) use and Clostridium difficile infections across multiple countries Method: National data covering the total population in Australia and Korea, the Canadian population over 65 years and a 3 million person random sample data set from Taiwan were assessed, as were data from a worker insurance population and a hospital inpatient/outpatient population in Japan. Sequence symmetry analysis was used to assess the association with oral vancomycin dispensing as the outcome of interest., Results: 54,957 patients were included. Positive associations were observed in Australia; adjusted sequence ratio (ASR) 2.48 (95% CI 1.90, 3.12), Korea ASR 2.15 (95%CI 2.11, 2.19), Canada ASR 1.45 (95% CI 1.16, 1.79), Japan hospital dataset ASR 3.21 (95%CI 2.12, 4.55) and Japan worker insurance dataset ASR 5.40 (95% CI 2.73, 8.75). The pooled result was ASR 2.40 (95%CI 1.88, 3.05) and 3.16 (95%CI 1.95, 5.10) when limited to Japan, Korean and Taiwan. Results did not vary by individual PPI. The temporal analysis showed effects within the first two weeks of PPI initiation., Conclusion: Our study confirms the association between PPI initiation and C. difficile infections across countries in the Asia-Pacific region.

The emergency department (ED) is commonly the first point of care for patients with acute behavioral issues from the community. Routinely, clinical management involves the use of benzodiazepine and/or antipsychotic drugs, when initial de-escalation strategies fail. There is currently scant literature available to inform the clinical management and resource utilization of acute agitation in the ED. This article discusses the approach to pharmacoeconomic studies of acute agitation management in the ED. It explores the conduct of such evaluations and highlights the cost and data sources required. The current difficulties experienced in conducting such evaluations are also discussed. Pharmacoeconomic studies related to the management of acute agitation in ED can be challenging. Robust clinical trials incorporating prospectively designed pharmacoeconomic studies will invariably contribute toward a better understanding of this therapeutic area and optimize the use of scarce resources.