Background: Over the last two decades, the prevalence of colistin resistance among the members of Enterobacteriaceae has been increasing, particularly among Klebsiella pneumoniae isolates; this limits the potential use of colistin and leads to worsened clinical outcomes.Methods: We investigated the prevalence and genetic characteristics of colistin-resistant K. pneumoniae (COLR-KP) in clinical isolates using genomic sequencing.Results: In total, 53 K. pneumoniae isolates (4.5%, 53/1,171) were confirmed as COLR-KP, of which eight isolates carried mobile colistin-resistant (mcr) gene. Although the overall prevalence rate (0.7%, 8/1,171) of mcr-like genes in clinical K. pneumoniae remained relatively low, the presence of mcr (15.1%, 8/53) among the COLR-KP isolates indicated that the mobile resistance gene was already widespread among K. pneumoniae isolates in hospital setting. We randomly selected 13 COLR-KP isolates (four mcr-bearing and nine non-mcr-bearing isolates) for whole-genome sequencing, including two pandrug-resistant and four sequence type 11 (ST11) isolates. Phylogenetic analysis revealed that all COLR-KP isolates were genetically diverse. Among the four mcr-bearing isolates, three (KP4, KP18, and KP30) were positive for mcr-1 and one (KP23) for mcr-8; none of the other mcr genes were detected. The mcr-1 in the KP4 and KP30 isolates were located in an IncX4 plasmid (approximately 33 kb) and could be successfully transferred to Escherichia coli J53AZ^R. In contrast, for the mcr-8-bearing plasmid in KP23 (IncFII), colistin resistance could not be transferred by conjugation. The mcr-1-producing isolate KP18 coexists a novel plasmid-carried tigecycline resistance gene tmexCD1-toprJ1. The most common chromosomal mutation associated with colistin resistance was a T246A amino acid substitution in PmrB, which was identified in most COLR-KP isolates (11/13, 84.6%). All ST11 isolates additionally had an R256G amino acid substitution. Critical virulence factors associated with hypervirulent K. pneumoniae were detected in four COLR-KP isolates; these virulence factors included aerobactin, salmochelin, and yersiniabactin.Conclusion: We found that mcr-bearing COLR-KP emerged in our hospital and was growing at an increasing rate. Simultaneous emergence of hypervirulence and colistin–tigecycline–carbapenem resistance in the epidemic clone ST11 K. pneumoniae was also observed; this highlights the significance of active and continuous surveillance.

Background: The malaria elimination plan of the Greater Mekong Subregion (GMS) is jeopardized by the increasing number of Plasmodium vivax infections and emergence of parasite strains with reduced susceptibility to the frontline drug treatment chloroquine/primaquine. This study aimed to determine the evolution of the P. vivax multidrug resistance 1 (Pvmdr1) gene in P. vivax parasites isolated from the China–Myanmar border area during the major phase of elimination. Methods: Clinical isolates were collected from 275 P. vivax patients in 2008, 2012–2013 and 2015 in the China–Myanmar border area and from 55 patients in central China. Comparison was made with parasites from three border regions of Thailand. Results: Overall, genetic diversity of the Pvmdr1 was relatively high in all border regions, and over the seven years in the China–Myanmar border, though slight temporal fluctuation was observed. Single nucleotide polymorphisms previously implicated in reduced chloroquine sensitivity were detected. In particular, M908L approached fixation in the China–Myanmar border area. The Y976F mutation sharply decreased from 18.5% in 2008 to 1.5% in 2012–2013 and disappeared in 2015, whereas F1076L steadily increased from 33.3% in 2008 to 77.8% in 2015. While neutrality tests suggested the action of purifying selection on the pvmdr1 gene, several likelihood-based algorithms detected positive as well as purifying selections operating on specific amino acids including M908L, T958M and F1076L. Fixation and selection of the nonsynonymous mutations are differently distributed across the three border regions and central China. Comparison with the global P. vivax populations clearly indicated clustering of haplotypes according to geographic locations. It is noteworthy that the temperate-zone parasites from central China were completely separated from the parasites from other parts of the GMS. Conclusions: This study showed that P. vivax populations in the China–Myanmar border has experienced major changes in the Pvmdr1 residues proposed to be associated with chloroquine resistance, suggesting that drug selection may play an important role in the evolution of this gene in the parasite populations.

Gametocyte is the sole form of the Plasmodium falciparum which is transmissible to the mosquito vector. Here, we report that an Apicomplexan Apetala2 (ApiAP2) family transcription factor, PfAP2-G2 (Pf3D7_1408200), plays a role in the development of gametocytes in P. falciparum by regulating the expression of PfMDV-1 (Pf3D7_1216500). Reverse transcriptase-quantitative PCR (RT-qPCR) analysis showed that PfAP2-G2 was highly expressed in the ring stage. Indirect immunofluorescence assay showed nuclear localization of PfAP2-G2 in asexual stages. The knockout of PfAP2-G2 led to a ~95% decrease in the number of mature gametocytes with a more substantial influence on the production and maturation of the male gametocytes, resulting in a higher female/male gametocyte ratio. To test the mechanism of this phenotype, RNA-seq and RT-qPCR showed that disruption of PfAP2-G2 led to the down-regulation of male development gene-1 (PfMDV-1) in asexual stages. We further found that PfAP2-G2 was enriched at the transcriptional start site (TSS) of PfMDV-1 by chromatin immunoprecipitation and qPCR assay in both ring stage and schizont stage, which demonstrated that PfMDV-1 is one of the targets of PfAP2-G2. In addition, RT-qPCR also showed that PfAP2-G (Pf3D7_1222600), the master regulator for sexual commitment, was also down-regulated in the PfAP2-G2 knockout parasites in the schizont stage, but no change in the ring stage. This phenomenon suggested that PfAP2-G2 played a role at the asexual stage for the development of parasite gametocytes and warrants further investigations in regulatory pathways of PfAP2-G2.

Candida auris is an emerging yeast species and an opportunistic pathogen. Due to its multi-drug resistance and ability to colonize and transmit, it poses a significant risk for outbreaks in medical institutions. In this study, we report the first case of C. auris detected in a pediatric bone marrow transplant child patient in Guangxi, China. C. auris was isolated from urine and identified using matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry, and the isolate belonged to clade I using sequencing. We have implemented stringent infection control measures including personal protective equipment and treatment in a single room, and conducted regular surveillance screening of patients’ body surfaces, as well as those of related medical and logistics personnel, medical equipment, and surrounding environmental surfaces. These measures aim to effectively control the colonization of C. auris in patients, prevent its spread within hospitals, and ensure the quality of diagnosis and treatment for patients.

Background. Exosomal microRNAs (miRNAs) have been linked to the genesis and progression of certain cancers. The role and regulation mechanism of cancer-derived exosomal miRNAs in CRC, however, remain unknown. Methods. To address this, we first used miRNA sequencing to describe the miRNA profiles of circulating exosomes in order to identify miRNAs that were differently expressed between patients with CRC and healthy controls. Transmission electron microscopy, nanoparticle tracking analysis (NTA), and western blot were used to analyze exosomes generated from CRC cells. CCK-8, wound healing, and Transwell tests were used to see whether exosomes affected CRC cell proliferation, metastasis, and apoptosis, respectively. We chose and identified hsa-miR-3937, which was abundant in tumor-generated exosomes, based on earlier RNA sequencing data of exosomes obtained and extracted from seven matched specimens of tumor tissues and surrounding normal tissues of CRC patients. Results. The role of hsa-miR-3937 in CRC cells was found, and silencing of hsa-miR-3937 decreased CRC cell invasion and migration in a Transwell experiment. Furthermore, we discovered that there was no link between hsa-miR-3937 expression and CRC cell apoptosis. Initially, it was discovered that BCL2L12 was the target gene of hsa-miR-3937, and the TCGA database highlighted the potential therapeutic relevance of BCL2L12. Furthermore, to identify hsa-miR-3937 as a biomarker of CRC, we used peripheral blood samples rather than patient tissues and extracted exosomes from plasma samples. To assess the expression levels and predictive usefulness of plasma exosomal hsa-miR-3937 in CRC, we performed RT-qPCR to identify hsa-miR-3937 levels in all samples. We also gathered clinicopathological information in order to look for links between aberrant hsa-miR-3937 expression and clinicopathological characteristics. The pathologic stage of CRC patients was linked to hsa-miR-3937 expression levels, and the same was true for the T stage. ROC curve study revealed that hsa-miR-3937 outperforms CEA and CA199. The combination of hsa-miR-3937, CEA, and CA199 exhibited the highest sensitivity for CRC diagnosis. Conclusions. Our findings show that the tumor-originated exosomal hsa-miR-3937 is a potential and effective liquid biopsy marker for colorectal cancer detection and therapy.