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Bloodstream infections by bacteria, especially multidrug-resistant bacteria, remain a worldwide public health concern. We evaluated the antibacterial activity of ceftobiprole and comparable drugs against different bloodstream isolates and different sequence types of methicillin-resistant Staphylococcus aureus (MRSA) in China. We found that MRSA, methicillin-susceptible Staphylococcus aureus (MSSA), and methicillin-susceptible coagulase-negative Staphylococcus (MSCNS) displayed ceftobiprole sensitivity rates of >95%, which are similar to the rates for linezolid, daptomycin, and vancomycin. Of the tested MRCNS strains, 90.4% were sensitive to ceftobiprole. The sensitivities of ST59, ST398, and ST22 MRSA to ceftobiprole were higher than that of ST239. Ceftobiprole's MIC50/90 value against Enterococcus faecalis was 0.25/2 mg/L, whereas Enterococcus faecium was completely resistant to this drug. Ceftobiprole exhibited no activity against ESBL-positive Enterobacterales, with resistance rates between 78.6% and 100%. For ESBL-negative Enterobacterales, excluding Klebsiella oxytoca, the sensitivity to ceftobiprole was comparable to that of ceftazidime, ceftriaxone, and cefepime. The MIC50/90 value of ceftobiprole against Pseudomonas aeruginosa was 2/16 mg/L, and for Acinetobacter baumannii, it was 32/>32 mg/L. Thus, ceftobiprole shows excellent antimicrobial activity against ESBL-negative Enterobacterales and Pseudomonas aeruginosa (comparable to that of ceftazidime, ceftriaxone, and cefepime); however, it is not effective against ESBL-positive Enterobacterales and Acinetobacter baumannii. These results provide important information to clinicians. [ABSTRACT FROM AUTHOR]

Carbapenem-resistant (CR) Klebsiella oxytoca complex can be associated with high mortality, emerging as a new threat to the public health. K. oxytoca complex is phylogenetically close to K. pneumoniae, one of most common species associated with multidrug resistance in Enterobacterale. The latest research showed that K. oxytoca is a complex of six species. Currently, the epidemiological and genomic characteristics of CR K. oxytoca complex in China are still unclear. Here, we conducted a multi-center study on 25 CR K. oxytoca complex collected from five representative regions in China. These isolates were, respectively, recovered from respiratory tract (12 cases, 48.0%), abdominal cavity (5 cases, 20.0%), blood (4 cases, 16.0%), urine tract (3 cases, 12.0%) and skin or soft tissue (1 cases, 4.0%). Among them, 32.0% (8/25) of patients infected with K. oxytoca complex had a poor prognosis. In this study, three K. oxytoca complex species were detected, namely K. michiganensis, K. oxytoca and K. pasteurii, among which K. michiganensis was the most common. Three carbapenemase genes were identified, including blaNDM-1 (10, 38.5%), blaKPC-2 (9, 34.6%) and blaIMP (6 blaIMP-4 and 1 blaIMP-8; 7, 26.9%). Subsequent multilocus sequence typing identified various sequence types (STs), among which ST43, ST92 and ST145 were relatively common. Different from the clonal dissemination of high-risk carbapenem-resistant K. pneumoniae strains, our research revealed a polyclonal dissemination characteristic of CR K. oxytoca complex in China. S1-nuclease PFGE and Southern blot experiment showed that carbapenemase genes were encoded in plasmids of different sizes. Two blaNDM-harboring plasmids were subsequently sequenced, and were characterized to be IncX3 and IncC incompatibility groups, respectively. This is the first multi-center study of CR K. oxytoca complex in China, which improved our understanding of the prevalence and antimicrobial resistance characteristics of CR K. oxytoca complex in China. [ABSTRACT FROM AUTHOR]

Objectives: Tigecycline is a last-resort antibiotic used to treat lethal infections caused by carbapenem-resistant Enterobacterales; however, plasmid-borne tigecycline resistance tmexCD-toprJ gene clusters can confer tigecycline resistance. The aim of the study was to identify novel subtypes and the spread of tmexCD-toprJ.Methods: Five non-duplicate isolates of different species, carrying tmexCD-toprJ gene clusters or novel subtypes, were isolated from patients across China between November 2018 and June 2019. WGS was performed using Illumina and Nanopore platforms. A phylogenetic tree was constructed using a dataset of 77 sequences carrying the tmexCD-toprJ gene clusters, 72 of which were downloaded from NCBI with a blastn identity cut-off of 95%.Results: We detected six different transfer units and two novel subtypes (tmexC1D1.2-toprJ1 and tmexC2D2.2-toprJ2) of the tmexCD-toprJ gene clusters. Among the six transfer units, three were mediated by IS26, while the rest were presumably mediated by Tn5393, hypothetical integrases (xerD-hp clusters-umuC-integrases-tnfxB2-tmexC2D2-toprJ2-umuC) and hypothetical units (hp-hp-hp-tnfxB2-tmexC2D2.2-toprJ2-ΔTn5393-Tn6292). Moreover, two tmexCD-toprJ-like gene clusters co-located on the same plasmid with blaNDM in five isolates. Phylogenetic analysis revealed that tmexCD-toprJ gene clusters may have originated in Pseudomonas spp., being mainly distributed in Pseudomonas spp. and Klebsiella spp. (64/77). Most tmexCD-toprJ gene clusters in Enterobacterales were located on plasmids, indicating that the gene clusters have a high inter-species transfer risk after transfer to Enterobacterales.Conclusions: In summary, to the best of our knowledge, this is the first report of tmexCD-toprJ gene clusters being isolated from Enterobacter cloacae and Klebsiella oxytoca, revealing that these multiple transfer units should be further studied because of their clinical significance. [ABSTRACT FROM AUTHOR]

Purpose: To assess the antimicrobial activities of ceftazidime/avibactam (CAZ/AVI) and aztreonam/avibactam (ATM/AVI) against carbapenem-resistant Enterobacteriaceae (CRE) isolates collected from three secondary hospitals in Southwest China between 2018 and 2019. Materials and Methods: A total of 120 unique CRE clinical isolates were collected and carbapenemase genes were detected using PCR. Antimicrobial susceptibility was determined using standard broth microdilution method and the results were interpreted according to CLSI breakpoints. Results: The 120 carbapenem-resistant strains included 92 Klebsiella pneumoniae, 10 Escherichia coli, 10 Enterobacter cloacae, five Klebsiella aerogenes, and three Klebsiella oxytoca isolates. Seventy-four percent of these 120 CRE isolates were collected from patients located in non-ICUs; 65.0% of these CRE isolates were collected from male patients; and 34.2% of these isolates were isolated from respiratory tracts. Four different carbapenemase genes were identified among 103 carbapenemase-producing Enterobacteriaceae (CPE) isolates, including blaKPC-2 (n=77), blaNDM-1 (n=16), blaNDM-5 (n=12) and blaIMP-4 (n=2). Overall, 21.7%, 37.5%, 40.8%, 75.0%, and 100% of the CRE strains were susceptible to levofloxacin, trimethoprim/sulfamethoxazole, amikacin, CAZ/AVI, and ATM/AVI, respectively. In addition, antimicrobial susceptibility testing showed that 96.7% isolates (n=116) were resistant to aztreonam, and the addition of avibactam (4 mg/L) significantly reduced the MICs of those aztreonam-resistant isolates by more than 128-fold (range: ≤ 0.125– 4 mg/L), and 90.0% (n=108) of total 120 isolates were inhibited at ATM/AVI concentration ≤ 1 mg/L. Conclusion: Our study revealed significant antimicrobial resistance among the CRE isolates against some commonly used antibiotics in three secondary Chinese hospitals. ATM/AVI exhibited potent activity against CRE isolates, including double carbapenemase-producing isolates, whereas CAZ/AVI was active against all KPC producers. [ABSTRACT FROM AUTHOR]

Background: Atopic dermatitis (AD) is a chronic, recurrent skin condition with recently increased incidence in younger children. AD development has been correlated with the skin microbiome, and Staphylococcus aureus enrichment causes significant increases in skin lesions.Objective: Our objectives were to compare the microbial diversity of the cheek skin of children with or without AD aged 0-1 years in China, and to determine whether 4 types of skin-isolated bacteria could inhibit S. aureus in vitro.Methods: The skin microbial samples of cheek skin of children were sequenced by 16S rRNA V1-V2 region. Four skin isolated bacterial fermentation supernatants were tested for effects on S. aureus growth, membrane formation, and induction of cytokine secretion from HaCaT cells.Results: Bacterial diversity decreased significantly in skin with severe AD compared to healthy skin (p < 0.01). Seven phyla had content >1%, 4 of which differed in AD (p < 0.05). 38 genera had content >1%, 15 differed (p < 0.05). Differences in 8 species were observed (p < 0.05). In vitro antibacterial and cellular experiments showed that S. aureus growth, biofilm formation, and induction of interleukin (IL)-1α and IL-6 secretion from HaCaT cells were significantly inhibited by Klebsiella oxytoca, Kocuria rhizophila, and Staphylococcus epidermidis culture supernatants (p < 0.05).Conclusion: Skin microbiome changes in children varied with age and with AD. There were complex interactions between skin isolated bacteria and S. aureus which could inhibit S. aureus growth and biofilm formation in vitro, suggesting that these microorganisms could be used in AD treatment. [ABSTRACT FROM AUTHOR]

Purpose: To determine the prevalence and epidemiology of fecal carriage of carbapenem-resistant Enterobacteriaceae (CRE), antimicrobial susceptibility, carbapenemase phenotype/genotype, and the colistin-resistance gene mcr-1 in a university hospital in China. Methods: A comprehensive study of the fecal carriage of CRE in 704 patients was performed. Multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE) were applied to elucidate the molecular epidemiology of the isolates. Results: In total, 60 CRE were detected in the 704 stool samples (8.5%), including 42 Klebsiella pneumoniae, 7 Escherichia coli, 3 Citrobacter freundii, 3 Klebsiella oxytoca, 3 Enterobacter cloacae, 1 Enterobacter aerogenes, and 1 Raoultella planticola. Fifty-five CRE isolates were positive for the carbapenemase phenotype, of which 39 were Klebsiella pneumoniae carbapenemase (KPC) producers. Thirty KPC-producing K. pneumoniae sequence type (ST) 11 isolates were identified and 28 were grouped into one cluster with a similarity of ≥85%, of predominately intensive care unit (ICU) strains. Three KPC-producing ST1889 strains were isolated from the pediatric ward, all indistinguishable and resistant to tigecycline. All CRE were susceptible to colistin and negative for mcr-1. Conclusion: This study revealed a predominant fecal carriage of the KPC-producing K. pneumoniae ST11 clone, with several indistinguishable strain clusters, and the emergence of ST1889 in a Chinese university hospital. This evidence of cross-infection supports the urgent need for the implementation of infection control measures to prevent CRE dissemination. [ABSTRACT FROM AUTHOR]

Klebsiella oxytoca causes opportunistic human infections and post-antibiotic haemorrhagic diarrhea. This Enterobacteriaceae species is genetically heterogeneous and is currently subdivided into seven phylogroups (Ko1 to Ko4 and Ko6 to Ko8). Here we investigated the taxonomic status of phylogroups Ko3 and Ko4. Genomic sequence-based phylogenetic analyses demonstrate that Ko3 and Ko4 formed well-defined sequence clusters related to, but distinct from, Klebsiella michiganensis (Ko1), K. oxytoca (Ko2), K. huaxiensis (Ko8), and K. grimontii (Ko6). The average nucleotide identity (ANI) of Ko3 and Ko4 were 90.7% with K. huaxiensis and 95.5% with K. grimontii , respectively. In addition, three strains of K. huaxiensis , a species so far described based on a single strain from a urinary tract infection patient in China, were isolated from cattle and human feces. Biochemical and MALDI-ToF mass spectrometry analysis allowed differentiating Ko3, Ko4, and Ko8 from the other K. oxytoca species. Based on these results, we propose the names Klebsiella spallanzanii for the Ko3 phylogroup, with SPARK_775_C1T (CIP 111695T and DSM 109531T) as type strain, and Klebsiella pasteurii for Ko4, with SPARK_836_C1T (CIP 111696T and DSM 109530T) as type strain. Strains of K. spallanzanii were isolated from human urine, cow feces, and farm surfaces, while strains of K. pasteurii were found in fecal carriage from humans, cows, and turtles. [ABSTRACT FROM AUTHOR]

Abstract: This study shows for the first time the mechanism of carbapenem resistance of a Klebsiella oxytoca clinical isolate ZC101 recovered from a Zhejiang University Hospital in Hangzhou, China. MIC values of imipenem, meropenem, and ertapenem for K. oxytoca ZC101 were 16, 16, and 128 μg/mL, respectively. Conjugation experiments demonstrated the transferability of a resistance determinant from K. oxytoca ZC101 to Escherichia coli EC600. Results from isoelectric focusing, polymerase chain reactions, and DNA sequencing confirmed that K. oxytoca ZC101 produced IMP-4 metallo-β-lactamase (MBL) and CTX-M-14 extended-spectrum β-lactamase, whereas E. coli transconjugant only produced the IMP-4. Amplification of integron revealed that bla IMP-4 gene is located within a class I integron that was carried in a plasmid approximately 55 kb in size. Sodium dodecyl sulfate polyacrylamide gel electrophoresis profiling of outer membrane proteins of K. oxytoca ZC101 indicated lack of expression of the OmpK36 porin. DNA sequence analysis of ompK36 gene of K. oxytoca ZC101 showed the gene was disrupted by an insertion sequence IS5. In all, the results show that plasmid-mediated IMP-4 MBL production combined with the loss of OmpK36 porin caused the resistance in K. oxytoca ZC101 to carbapenems. [Copyright &y& Elsevier]

Objectives: Recently, the Gram-negative bacterium Klebsiella oxytoca has been identified as an emerging pathogen. Here we report the draft genome of a 2,3-butanediol-producing strain, K. oxytoca CCTCC M207023, isolated from soil in Nanjing, China. The tetracycline-resistant phenotype and the high yield of 2,3-butanediol was demonstrated., Methods: The draft genome of K. oxytoca CCTCC M207023 was determined using an Illumina NovaSeq™ 6000 next-generation DNA sequencing platform. Clean sequencing data were subsequently assembled using SOAPdenovo., Results: The draft genome of K. oxytoca CCTCC M207023, comprising 5 658 144bp and with a GC content of 56.50%, was assembled into 5262 open-reading frames (ORFs). Antimicrobial resistance genes were also annotated., Conclusions: The draft genome sequence of K. oxytoca CCTCC M207023 reported here will be a reference for comparative analysis with the antimicrobial resistance mechanisms for the safety of 2,3-butanediol industrial production., (Copyright © 2019 International Society for Antimicrobial Chemotherapy. Published by Elsevier Ltd. All rights reserved.)

A strain of a member of the genus Klebsiella, WCHKl090001, was recovered from a human urine sample in PR China in 2017. Phylogenetic analysis based on gyrA and rpoB housekeeping genes revealed that the strain was distinct from any previously described species of the genus Klebsiella though it was clustered with the Klebsiella oxytoca phylogroup, including Klebsiella grimontii, Klebsiella michiganensis and Klebsiella oxytoca. The whole-genome sequence of strain WCHKl090001 has an up to 87.18 % average nucleotide identity with those of type strains of all known species of the genus Klebsiella. In silico DNA-DNA hybridization (isDDH) values between strain WCHKl090001 and type strains of all known species of the genus Klebsiella ranged from 22.3 to 35.2 %. Strain WCHKl090001 could be distinguished from species of the Klebsiella oxytocaphylogroup by its negative Voges-Proskauer reaction. Genotypic and phenotypic characteristics from this study indicate that strain WCHKl090001 should be considered to represent a novel species of the genus Klebsiella, for which the name Klebsiellahuaxiensis sp. nov. is proposed. The type strain is WCHKl090001 T (=GDMCC 1.1379 T =CNCTC 7650 T ).

Objectives: To explore the mechanisms of imipenem resistance in Klebsiella spp. and the transmission of Klebsiella pneumoniae Carbapenemase-2( KPC -2) gene in Klebsiella species., Methods: The imipenem resistant Klebsiella pneumoniae and Klebsiella oxytoca were isolated in the West China Hospital of Sichuan University in 2009/2010 and 2012/2013. Their minimal inhibitory concentration (MIC) was determined by agar dilution method. CARB ChromID plate and improved Hodge test were undertaken to detect carbapenemases resistant phenotype. PCR method was used for detecting KPC-2 gene. Plasmid transmission was detected by plasmid conjugation tests. The homology of the plasmids and the strains was analyzed using random amplified polymorphic DNA (RAPD) and enterobacterial repetitive intergenic consensus PCR(ERIC-PCR) methods., Results: Three strains of Klebsiella oxytoca collected in 2009/2010 and 7 Klebsiella pneumoniae collected in 2012/2013 developed carbapenemases resistance, all of which carried KPC -2 gene. The 3 KPC -2 positive plasmids isolated from Klebsiella oxytoca transited to recipient organisms and showed homology with the 7 KPC -2 gene positive plasmids isolated from Klebsiella pneumoniae . The ERIC-PCR showed homology of the 7 KPC positive Klebsiella pneumoniae ., Conclusions: Carbapenemases in Klebsiella spp with expressed KPC -2 gene contribute to the development of resistance in this hospital. The transmission of KPC -2 plasmid in Klebsiella oxytoca may cause imipenem resistance in Klebsiella pneumonia . The horizontal transmission may be the main mechanism in the spread of imipenem resistance in Klebsiella spp .