Cryptococcus gattii strains with a high phagocytosis phenotype by macrophages display high pathogenicity at the early stage of infection in vivo.

Cryptococcus gattii (Cg) is a facultative intracellular pathogen that can replicate and disseminate in mammalian macrophages, causing life-threatening cryptococcosis in both immunocompetent and immunocompromised individuals. Cryptococcus-macrophage interactions are crucial for cryptococcosis prognosis. However, the relationship between Cg pathogenicity and phagocytosis by macrophages has not yet been investigated in depth. In this study, a series of in vitro and in vivo experiments were conducted to investigate the interaction between macrophages and Cg. Flow cytometry was used to detect the phagocytic phenotypes of the Cg strains within macrophages. Scanning electron microscopy, transmission electron microscopy, and immunofluorescence were used to observe phagocytosis and proliferation, respectively. Survival and lung fungal burden tests were also performed. Our results show that Cg cells display different phagocytosis phenotypes, which are independent of the molecular type. Within macrophages, the high phagocytosis phenotype (HP) strains obtain higher intracellular proliferation than the low phagocytosis phenotype (LP) strains. At the early stage of infection in vivo, HP-inducing permissive granulomas within the lungs seldom limit the dissemination of cryptococci. In addition, HP strains could inhibit the formation of M1-type macrophages, proliferate intracellularly and disseminate extracellularly, and cause hypoxia induced by mucus and acidic polysaccharide accumulation in pulmonary alveoli much earlier than LP strains in vivo. Our work reveals that Cg displays diverse interactions with macrophages, which may enhance our understanding of the pathogenicity of this life-threatening pathogen.

Significance of differential expression profiles of ABC transporters in azole susceptibility between Cryptococcus gattii VGI and VGII strains.

Azoles were used as the primary antifungal agents to treat the Cryptococcus gattii infection. Evidence showed that subtypes of C. gattii respond differently to azoles, but the mechanism is largely elusive. In this study, we aimed to find the mechanisms of differences in azole drug susceptibility in different subtypes of C. gattii. Eight clinical strains of C. gattii were collected for molecular typing, multilocus sequence typing (MLST) analysis, and antifungal susceptibility testing. Based on drug susceptibility differences, the RNA sequencing data were analyzed to find candidate azole drug susceptibility genes, and qPCR validation was performed. Five VGI subtypes and three VGII subtypes were identified among the eight strains of C. gattii. The clinical isolates showed high genetic diversity, and seven sequence types (STs) were identified. The geometric mean (GM) of minimum inhibitory concentration (MIC) for fluconazole, voriconazole, and itraconazole of VGI subtype was significantly lower than that of VGII subtype, and genes related to transporter activities were differentially expressed between VGI and VGII strains. The results of the Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the DEGs (differential expressed genes) were found to be enriched in multiple ABC transporters. We further performed qPCR to quantify the expression level of seven ABC transporters. We found that ABC transporters ATM1, MDR1, PDR5, PDR5-3, and PXA2 were expressed significantly higher in VGII strains than in VGI strains. Our work revealed four novel ABC transporters, ATM1, PDR5, PDR5-3, and PXA2, promising candidate targets regulating azole susceptibility in C. gattii strains. LAY SUMMARY: Azoles were used as the primary antifungal agents for treating Cryptococuss gattii infection. Since subtypes of C. gattii respond differently to azoles. We analyzed mRNA expression profiles of different subtypes and identified four ABC transporters that could be potential genes regulating azole sensitivity.

Real-time Screening of Specimen Pools for Coronavirus Disease 2019 (COVID-19) Infection at Sanya Airport, Hainan Island, China.

A 10:1 pooled test strategy on-site at an airport of China was pursued, resulting in increased test throughput, limited use of reagents, and increased testing efficiency without loss of sensitivity. This testing approach has the potential to reduce the need for contact tracing when the results are delivered first time.

Clinical and microbiological characteristics of Cryptococcus gattii isolated from 7 hospitals in China.

BACKGROUND: Infection, even outbreak, caused by Cryptococcus gattii (C. gattii) has been reported in Canada and the United States, but there were sparsely-reported cases of C. gattii in China. Our interest in occurrence, clinical manifestation, laboratory identification and molecular characterization of Chinese C. gattii strains leads us to this research. RESULTS: Out of 254 clinical isolates, initially identified as Cryptococcus neoformans (C. neoformans), eight strains were re-identified as C. gattii. Multi-locus sequence typing (MLST) showed genotype VGI accounted for the most (6 / 8), the other two strains were genotype VGII (VGIIa and VGIIb respectively) with 3 specific spectra of molecular weight about 4342, 8686, 9611 Da by MALDI-TOF MS. The minimal inhibitory concentrations (MICs) of Fluconazole with Yeast one was 2~4 times higher than that with ATB fungus 3 and MICs of antifungal agents against VGII strains were higher than against VGI strains. Comparative proteome analysis showed that 329 and 180 proteins were highly expressed by C. gattii VGI and VGII respectively. The enrichment of differentially expressed proteins was directed to Golgi complex. CONCLUSIONS: Infection by C. gattii in China occurred sparsely. Genotype VGI was predominant but VGII was more resistant to antifungal agents. There was significant difference in protein expression profile between isolates of VGI and VGII C. gattii.

Prevalence and characteristics of surgical site hypervirulent Klebsiella pneumoniae isolates.

BACKGROUND: We aim to determine the prevalence of hypervirulent Klebsiella pneumoniae (hvKp), which causes surgical site infections (SSIs), and describe the microbiological and molecular characteristics of hvKp isolates. METHODS: Non-duplicate K. pneumoniae strains were isolated from wound drainage specimens of postoperative patients at the Chinese PLA General Hospital between September 2008 and July 2017. Antimicrobial susceptibility, string test, pulsed-field gel electrophoresis (PFGE), and genome sequencing analyses were performed. RESULTS: Fifty-one K. pneumoniae strains were isolated from wound drainage specimens collected from postoperative patients. Twenty-six hvKp strains, including 17 (17/37, 46.0%) and 9 (9/14, 64.3%) hvKp strains, were isolated from 37 and 14 patients with SSIs and community-acquired infections (CAIs), respectively. Notably, 4 extended-spectrum beta-lactamase (ESBL)-producing hvKp strains (4/26, 15.4%) and 2 carbapenem-resistant hvKp strains (2/26, 7.7%) were found. Thirteen K1 serotype (13/26, 50.0%) and 7 K2 serotype (7/26, 26.9%) strains were identified. Phylogenetic analysis results showed that 13 K1 serotype isolates exhibited a high degree of clonality, while 7 K2 serotype strains were genetically unrelated. MLST analysis indicated that there was a strong correlation between ST23 and the K1 serotype. ST65, ST86, and ST375 were prevalent in K2 serotype strains. Almost all hvKp strains (24/26, 92.3%) harbored large virulence plasmids with a high degree of homology to pNTUH-K2044 and sizes ranging from 140 to 220 kbp. CONCLUSIONS: HvKp strains were prevalent in SSIs. Effective surveillance and control measures should be implemented to prevent the dissemination of such organisms, including the ESBL-producing and carbapenem-resistant hvKp strains.

Emergence of a Multidrug-Resistant Hypervirulent Klebsiella pneumoniae Sequence Type 23 Strain with a Rare blaCTX-M-24-Harboring Virulence Plasmid.

Here, we report a multidrug-resistant hypervirulent Klebsiella pneumoniae (MDR-HvKP) strain of sequence type 23 (ST23) with a rare hybrid plasmid harboring virulence genes and blaCTX-M-24, and we analyze the genetic basis for relationship between genotypes and MDR-hypervirulence phenotypes. Further analysis indicates that the hybrid plasmid is formed by IS903D-mediated intermolecular transposition of the blaCTX-M-24 gene into the virulence plasmid. The emergence of MDR-HvKP strains, especially those carrying drug-resistant virulent plasmids, poses unprecedented threats/challenges to public health. This is a dangerous trend and should be closely monitored.

Bacteremia and other body site infection caused by hypervirulent and classic Klebsiella pneumoniae.

OBJECTIVES: To investigate bacteremia and other body site infection caused by hypervirulent Klebsiella pneumoniae (hvKP), a recently recognized pathogen of invasive infection, and classic Klebsiella pneumoniae (cKP), a very common organism associated with many kinds of nosocomial infection. METHODS: Clinical information obtained from patients with both bacteremia and other body site infections caused by hvKP and/or cKP was retrospectively reviewed. Homo-hvKP (or homo-cKP) was defined as homologous hvKP (or cKP) strains from different body sites in each individual patient according to string test, virulence gene amplification and PFGE pattern. MLST was carried on to understand the correlation of sequence type with capsular polysaccharide type for Klebsiella pneumoniae from blood. RESULTS: Sixty-four hvKP and 101 cKP strains were isolated from blood and other body sites of 76 patients who had bacteremia accompanied by other site infection. Among these patients, 27 were infected with homo-hvKP, 32 were with homo-cKP, 12 were with heterogeneous cKP, and five were with both hvKP and cKP. Patients with bacteremia and liver abscesses caused by homo-hvKP accounted for 51.9%, and 92.6% of homo-hvKP infected patients did not receive any invasive procedures before bacteremia. However, patients with bacteremia and biliary tract infection caused by homo-cKP accounted for 34.4%, and 78.1% of homo-cKP infected patients had history of invasive procedures before bacteremia. More homo-hvKP strains (59.3%) than homo-cKP strains (34.4%) were isolated from blood earlier than other sites. HvKP strains were statistically more susceptible to the tested antimicrobials than cKP strains. An outbreak of carbapenem-resistant cKP infection and possible gene transfer of KPC-2 from cKP to hvKP were brought to notice. CONCLUSIONS: Both hvKP and cKP could cause bacteremia and other body site infection. But patients with hvKP bacteremia usually suffered from liver abscess without previous invasive procedures, most patients with cKP bacteremia had history of invasive medical procedures.

[The clinical and bacterial features of Klebsiella pnuemoniae liver abscess].

OBJECTIVE: To summarize the clinical and bacterial features of Klebsiella pnuemoniae liver abscess (KPLA) in order to provide the basis for the diagnosis and treatment of KPLA. METHODS: Retrospective study was conducted. One hundred and fifty-two medical records, from 3 teaching hospitals in Beijing, between January 2010 and December 2014, were collected. Among which 137 complete medical records were analyzed. String test was carried out to detect the hypermucoviscosity phenotype. PCR was performed to check the capsular serotype and the virulent genes. Disk diffusion method was operated to obtain the antimicrobial resistance rates. The results were analyzed by chi-square test. RESULTS: KPLA occurred mostly in middle-aged, male and diabetes mellitus patients. 92.7% (127/137) patients had fever. 80.3% (110/137) of the KLPA were single abscess, among which 80.9% (89/110) were in the right lobe and 33.6% (46/137) had air cavities.74.5% (102/137) of the white blood cell count, 83.2% (114/137) of the neutrophils' percentage, 78.1% (107/137) of alanine aminotransferase and 51.8% (71/137) of the total billrubin were elevated. 87.5% (133/152) of the Klebsiella pnuemoniae (Kpn) appeared to be hypermucoviscous, K1 was the most popular serotype, the second was K2, and the positive rates of virulent genes rmpA and aerobactin were 82.9% (126/152) and 88.2% (134/152), respectively. Among the isolates from the KPLA without other hepatobiliary diseases, the portion of K1 serotype, the positive rates of rmpA and aerobactin were 65.7%, 94.9% and 96.0%, respectively, higher than those of the 28.9%, 50.0% and 68.4% from the KPLA with other hepatobiliary diseases, while the undefined serotype potion was lower (5.1% vs 26.3%), the differences were statistically significant (χ(2)=14.98, 38.40, 17.61, 10.65, all P<0.01). Most of Kpn were susceptible to antimicrobials. CONCLUSIONS: KPLA has certain clinical features, and are mostly caused by hypervirulent isolates that are hypermucoviscous with rmpA and aerobactin genes. Most of the isolates are susceptible to antimicrobials.

Universal Probe Library based real-time PCR for rapid detection of bacterial pathogens from positive blood culture bottles.

A set of real-time PCR based assays using the locked nucleic acid probes from Roche Universal ProbeLibrary were developed for rapid detection of eight bacterial species from positive blood culture bottles. Four duplex real-time PCR reactions targeting to one Gram-positive bacterium and one Gram-negative bacterium were optimized for species identification according to Gram stain results. We also included mecA-specific primers and probes in the assays to indicate the presence of methicillin resistance in the bacterial species. The analytical sensitivity was in the range of 1-10 CFU per PCR reaction mixture. The specificity and cross reactivity of the assay was validated by 28 ATCC reference strains and 77 negative blood culture specimens. No cross-reactivity was observed in these samples thus demonstrating 100 % specificity. 72 previously characterized clinical isolates were tested by the real-time PCR assay and validated the accuracy and feasibility of the real-time PCR assay. Furthermore, 55 positive blood culture samples were tested using real-time PCR and 50 (90.9 %) of them were identified as the same species as judged by biochemical analysis. In total, real-time PCR showed 98.2 % consistent to that of traditional methods. Real-time PCR can be used as a supplement for early detection of the frequently-occurred pathogens from the positive blood cultures.

Epidemiological characteristics, virulence potential, antimicrobial resistance profiles, and phylogenetic analysis of Aeromonas caviae isolated from extra-intestinal infections.

Objective: Aeromonas caviae (A. caviae) is one of the major etiological agents in human intestinal infections reported to be associated with a broad spectrum of extra-intestinal infections with increasing incidence over recent years. Although previous studies have established its significance as a causative agent of both bloodstream and gastrointestinal infections, the characteristics of A. caviae that cause extra-intestinal infections remain unilluminated.In this single-center retrospective study, we investigated epidemiological characteristics, antimicrobial resistance genes and phenotypes, virulence genes, and phyloevolution of 47 clinical A. caviae isolated from patients with extra-intestinal infections from 2017 to 2020. Methods: A. caviae strains were identified by biochemical tests and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF/MS), ultimately confirmed to species level by whole-genome sequencing (WGS). Antimicrobial resistance and virulence genes were identified using the Comprehensive Antibiotic Resistance Database (CARD) and the virulence factor database (VFDB), respectively. Phylogenetic analysis of 47 clinical strains was performed by combining with 521 A. caviae strains from NCBI database. Results: A. caviae was an opportunistic pathogen in immunocompromised patients, especially those with underlying hepatobiliary diseases and malignancies. 19 out of 47 isolates were identified as multidrug resistance (MDR) strains. Piperacillin-tazobactam, levofloxacin, gentamicin, amikacin with a resistance rate of less than 10% remained as options to treat extra-intestinal infections. 24 out of 47 isolates exhibited non-susceptibility to cephalosporins and cephamycins, all of which carried ß-lactamase gene, including bla MOX, bla PER-3, bla OXA, bla NDM, and bla CphA. Most stains (98%, 46/47) carried at least one of the virulence genes, but extra-intestinal infections had a low mortality rate. Phylogenetic analysis indicated the risk of nosocomial transmission but revealed no outbreak. However, the emergence of MDR and ß-lactamase resistance genes in extra-intestinal isolates of A. caviae is becoming an increasing risk to public health and requires attention. Conclusions: This study strengthen our understanding of A.caviae isolated from extra-intestinal infections. It may contribute to the management of extra-intestinal infections as well as the prevention and control of drug resistance.

Correction: Molecular epidemiology and microbiological characteristics of Cryptococcus gattii VGII isolates from China.

[This corrects the article DOI: 10.1371/journal.pntd.0010078.].

Virulence profiling of Cryptococcus gattii isolates in China: insights from a multi-center study.

IMPORTANCE: Our study indicates that the molecular typing of Cryptococcus gattii is unrelated to virulence. The integration of animal experiments and clinical prognosis demonstrated that pathogenicity did not exhibit a direct correlation with in vitro virulence phenotypes or molecular genotypes, emphasizing the intricate nature of virulence. In conclusion, our research holds the potential to provide valuable insights into understanding the microbiological attributes of C. gattii in China.

Clinical and microbiological characterization of Staphylococcus lugdunensis isolates obtained from clinical specimens in a hospital in China.

BACKGROUND: Several reports have associated Staphylococcus lugdunensis with the incidence of severe infection in humans; however, the frequency and prevalence of this microorganism and thus the propensity of its antimicrobial drug resistance is unknown in China. The objective of the current study was to determine the prevalence of Staphylococcus lugdunensis among six hundred and seventy non-replicate coagulase negative Staphylococcus (CoNS) isolates collected in a 12-month period from clinical specimens in the General Hospital of the People's Liberation Army in Beijing, China. RESULTS: Five (0.7%) of the 670 isolates of CoNS were identified as S. lugdunensis. Whereas three isolates were resistant to erythromycin, clindamycin, and penicillin and carried the ermC gene and a fourth one was resistant to cefoxitin and penicillin and carried the mecA gene, one isolate was not resistant to any of the tested antimicrobials. Pulse field gel electrophoretic analysis did not reveal widespread epidemiological diversity of the different isolates. CONCLUSION: Hence, even though S. lugdunensis may be yet unrecognized and undefined in China, it still might be the infrequent cause of infection and profound multi-drug resistance in the same population.

Genomic Analysis of KPC-2-Producing Klebsiella pneumoniae ST11 Isolates at the Respiratory Department of a Tertiary Care Hospital in Beijing, China.

Background: Carbapenem-resistant Klebsiella pneumoniae (CRKP) is an important pathogen causing hospital-associated outbreaks worldwide. The spread of K. pneumoniae carbapenemase-2 (KPC-2)-producing CRKP is primarily associated with sequence type (ST) 11. Methods: A total of 152 KPC-2-producing K. pneumoniae ST11 isolates were collected from the respiratory department of a tertiary care hospital in Beijing, China between 2009 and 2018. The genome sequencing of these isolates was performed on the HiSeq X Ten sequencer. Multilocus sequence typing (MLST), capsular type, plasmid replicon types and resistance genes were identified. Fifteen isolates were selected for the subsequent single-molecule real-time (SMRT) sequencing on the PacBio RS II. Alignment of the complete sequences of the plasmids carrying bla KPC-2 and/or virulence genes was performed by using BRIG and Easyfig. Results: From 2012 to 2018, the detection rate of the bla KPC-2-carrying CRKP rose rapidly from 3.3 to 28.1%. KPC-2-producing K. pneumoniae ST11 isolates were dominant in CRKP, which emerged in 2012 and caused several outbreaks. Most isolates exhibited multidrug-resistant to commonly used antibiotics, while all the isolates remained susceptible to tigecycline and polymyxin B. The single nucleotide polymorphism (SNP) analysis showed that all these 152 KPC-2-producing K. pneumoniae ST11 isolates could be divided into three genetically distinct clades (A, B, and C) and eleven subclades (A1-A9 and B1-B2). The majority belonged to clade A with KL47 serotype (n = 117, 77.0%), while KL64 and KL16 were identified in clades B and C, respectively. The bla KPC-2-carrying plasmids exhibited diverse types, namely, IncFII (pHN7A8)/IncR(6/15), IncFII (pHN7A8)/IncpA1763-KPC (5/15), IncFII (pHN7A8) (1/15), IncR (1/15), and IncpA1763-KPC (1/15). The genetic environment of bla KPC-2 showed nine IS26-based composite transposons, which had a basic core structure ISKpn27-bla KPC-2-ΔISKpn6. About 27.6% (42/152) isolates co-carried 2 to 4 virulence marker genes (namely, peg344, iucA, iroB, rmpA, and rmpA2) for hvKp strains. At least three isolates were identified to harbor virulence gene-carrying plasmids. Conclusion: KPC-2-producing K. pneumoniae ST11 was highly heterogeneous in our hospital. Transmission of these strains was mainly mediated by twelve high-risk clones. The bla KPC-2-carrying plasmids and genetic environment of bla KPC-2 genes exhibited active evolution in K. pneumoniae ST11. More attention should be paid to the tendency of KPC-2-ST11 to acquire hypervirulent plasmids.

Cryptococcus escapes host immunity: What do we know?

Cryptococcus is an invasive fungus that seriously endangers human life and health, with a complex and well-established immune-escaping mechanism that interferes with the function of the host immune system. Cryptococcus can attenuate the host's correct recognition of the fungal antigen and escape the immune response mediated by host phagocytes, innate lymphoid cells, T lymphocytes, B lymphocytes with antibodies, and peripheral cytokines. In addition, the capsule, melanin, dormancy, Titan cells, biofilm, and other related structures of Cryptococcus are also involved in the process of escaping the host's immunity, as well as enhancing the ability of Cryptococcus to infect the host.

Molecular epidemiology and microbiological characteristics of Cryptococcus gattii VGII isolates from China.

Cryptococcus gattii (C. gattii) is a fungal pathogen that once caused an outbreak of cryptococcosis on Vancouver Island, and had spread worldwide, while few data were available in China. In this study, seven clinical isolates of C. gattii VGII were collected from 19 hospitals, Multi-locus Sequence Typing (MLST) analysis and whole-genome sequencing (WGS) was performed, combined with published data for phylogenetic analysis. In addition, in vitro antifungal susceptibility testing, phenotypic analysis, and in vivo virulence studies were performed, subsequently, histopathological analysis of lung tissue was performed. C.gattii VGII infected patients were mainly immunocompetent male, and most of them had symptoms of central nervous system (CNS) involvement. MLST results showed that isolates from China exhibited high genetic diversity, and sequence type (ST) 7 was the major ST among the isolates. Some clinical isolates showed a close phylogenetic relationship with strains from Australia and South America. All clinical isolates did not show resistance to antifungal drugs. In addition, there was no correlation between virulence factors (temperature, melanin production, and capsule size) and virulence while in vivo experiments showed significant differences in virulence among strains. Lung fungal burden and damage to lung tissue correlated with virulence, and degree of damage to lung tissue in mice may highlight differences in virulence. Our work seeks to provide useful data for molecular epidemiology, antifungal susceptibility, and virulence differences of C. gattii VGII in China.

Comparison of three species of Elizabethkingia genus by whole-genome sequence analysis.

Elizabethkingia are found to cause severe neonatal meningitis, nosocomial pneumonia, endocarditis and bacteremia. However, there are few studies on Elizabethkingia genus by comparative genomic analysis. In this study, three species of Elizabethkingia were found: E. meningoseptica, E. anophelis and E. miricola. Resistance genes and associated proteins of seven classes of antibiotics including beta-lactams, aminoglycosides, macrolides, tetracyclines, quinolones, sulfonamides and glycopeptides, as well as multidrug resistance efflux pumps were identified from 20 clinical isolates of Elizabethkingia by whole-genome sequence. Genotype and phenotype displayed a good consistency in beta-lactams, aminoglycosides and glycopeptides, while contradictions exhibited in tetracyclines, quinolones and sulfonamides. Virulence factors and associated genes such as hsp60 (htpB), exopolysaccharide (EPS) (galE/pgi), Mg2+ transport (mgtB/mgtE) and catalase (katA/katG) existed in all clinical and reference strains. The functional analysis of the clusters of orthologous groups indicated that 'metabolism' occupied the largest part in core genome, 'information storage and processing' was the largest group in both accessory genome and unique genome. Abundant mobile elements were identified in E. meningoseptica and E. anophelis. The most significant finding in our study was that a single clone of E. anophelis had been circulating within diversities of departments in a clinical setting for nearly 18 months.

Genetic diversity and transmission patterns of Burkholderia pseudomallei on Hainan island, China, revealed by a population genomics analysis.

Burkholderia pseudomallei is a Gram-negative soil-dwelling bacillus that causes melioidosis, a frequently fatal infectious disease, in tropical and subtropical regions. Previous studies have identified the overall genetic and evolutionary characteristics of B. pseudomallei on a global scale, including its origin and transmission routes. However, beyond its known hyperendemicity foci in northern Australia and Southeast Asia, the distribution and genetic characteristics of B. pseudomallei in most tropical regions remain poorly understood, including in southern China. Here, we sequenced the genomes of 122 B. pseudomallei strains collected from Hainan, an island in southern China, in 2002-2018, to investigate the population structure, relationships with global strains, local epidemiology, and virulence and antimicrobial-resistance factors. A phylogenetic analysis and hierarchical clustering divided the Hainan strains into nine phylogenic groups (PGs), 80 % of which were concentrated within five major groups (group 1: corresponding to minor sequence types [STs], 12.3 %; group 3: ST46 and ST50, 31.1 %; group 9: ST58, 13.1 %; group 11: ST55, 8.2 %; group 15: mainly ST658, 15.6%). A phylogenetic analysis that included global strains suggested that B. pseudomallei in Hainan originated from Southeast Asian countries, transmitted in multiple historical importation events. We also identified several mutual transmission events between Hainan and Southeast Asian countries in recent years, including three importation events from Thailand and Singapore to Hainan and three exportation events from Hainan to Singapore, Malaysia, and Taiwan island. A statistical analysis of the temporal distribution showed that the Hainan strains of groups 3, 9, and 15 have dominated the disease epidemic locally in the last 5 years. The spatial distribution of the Hainan strains demonstrated that some PGs are distributed in different cities on Hainan island, and by combining phylogenic and geographic distribution information, we detected 21 between-city transmission events, indicating its frequent local transmission. The detection of virulence factor genes showed that 56 % of the Hainan strains in group 1 encode a B. pseudomallei-specific adherence factor, boaB, confirming the specific pathogenic characteristics of the Hainan strains in group 1. An analysis of the antimicrobial-resistance potential of B. pseudomallei showed that various kinds of alterations were identified in clinically relevant antibiotic resistance factors, such as AmrR, PenA and PBP3, etc. Our results clarify the population structure, local epidemiology, and pathogenic characteristics of B. pseudomallei in Hainan, providing further insight into its regional and global transmission networks and improving our knowledge of its global phylogeography.

Robinsoniella peoriensis bacteremia in a patient with pancreatic cancer.

Robinsoniella peoriensis was recently identified as a Gram-positive, spore-forming, anaerobic rod originally isolated from swine manure storage pits. We describe here a case of R. peoriensis bacteremia in a 42-year-old male with pancreatic cancer. The identification was confirmed by unique phenotypic profiles and partial 16S rRNA gene sequences.

A rare carbapenem-resistant hypervirulent K1/ST1265 Klebsiella pneumoniae with an untypeable blaKPC-harboured conjugative plasmid.

OBJECTIVE: We investigated the pathogenesis of a patient with severe acute pancreatitis by comprehensively analysing a rare carbapenem-resistant hypervirulent K1/ST1265 Klebsiella pneumoniae (CR-HvKP) strain. METHODS: We conducted virulence and multidrug-resistance phenotypic characterization and identified a CR-HvKP strain from the patient. It was subjected to Pacbio sequencing, and subsequent analysis of virulence, resistance genes and mobile genetic elements. RESULTS: We described the phenotype and genotype of a rare CR-HvKP strain with an untypeable blaKPC-harboured conjugative plasmid and a pLVPK-like virulent plasmid. Resistance gene analysis showed that the untypeable blaKPC-2-harboured plasmid was formed by IS26-mediated recombination of blaKPC-embedded transposon Tn6500 into pCN061p4 from Escherichia coli. Interestingly, it had an R-M system that might protect plasmid from cleavage. This may facilitate the stabilization of plasmids in bacteria in the event of missing CR-plasmid during transmission. Virulence gene analysis indicated 78 virulence genes on the genome, including 67 on the chromosome (37 in high-pathogenic island) and 11 on the pLVPK-like virulence plasmid (harbouring rmpA/rmpA2). Further phylogenetic analysis revealed that the CR-HvKP evolved from HvKP through acquiring an antimicrobial-resistance plasmid. CONCLUSION: Our research, to our knowledge, first reported a ST1265/K1 CR-HvKP strain with an untypeable blaKPC-harboured plasmid. The trend that HvKP could evolve into CR-HvKP by obtaining stabilized/conjugative blaKPC-carrying plasmids is a considerable threat to public health and should be closely supervised.