A carbapenem-resistant Klebsiella pneumoniae strain 628 was isolated from a human case of intracranial infection in a Chinese teaching hospital. Strain 628 produces KPC-2 and CTX-M-55 encoded by two different conjugative plasmids, i.e., the IncFIIK plasmid p628-KPC and the IncI1 plasmid p628-CTXM, respectively. blaKPC-2 is captured by a Tn1721-based unit transposon with a linear structure ΔTn3-ISKpn27-blaKPC-2-ΔISKpn6-ΔTn1721, and this transposon together with a mercury resistance (mer) gene locus constitutes a 34 kb acquired drug-resistance region. blaKPC-2 has two transcription starts (nucleotides G and C located at 39 and 250 bp upstream of its coding region, respectively), which correspond to two promoters, i.e., the intrinsic P1 and the upstream ISKpn27/Tn3-provided P2 with the core -35/-10 elements TAATCC/TTACAT and TTGACA/AATAAT, respectively. blaCTX-M-55 is mobilized in an ISEcp1-blaCTX-M-55-Δorf477 transposition unit and appears to be the sole drug-resistant determinant in p628-CTXM. blaCTX-M-55 possesses a single transcription start (nucleotides G located at 116 bp upstream of its coding region), corresponding to the ISEcp1-provided P1 promoter with the core -35/-10 element TTGAAA/TACAAT. All the above detected promoters display a characteristic of constitutive expression. Coexistence of blaKPC and blaCTX-M in K. pneumoniae has been reported many times, but this is the first report to gain deep insights into genetic platforms, promoters, and expression of the two coexisted bla genes with determination of entire nucleotide sequences of the two corresponding plasmids.

Carbapenem-resistant Klebsiella pneumoniae is one of the primary bacterial pathogens that pose a significant threat to global public health because of the lack of available therapeutic options. Phage therapy shows promise as a potential alternative to current antimicrobial chemotherapies. In this study, we isolated a new Siphoviridae phage vB_KpnS_SXFY507 against KPC-producing K. pneumoniae from hospital sewage. It had a short latent period of 20 min and a large burst size of 246 phages/cell. The host range of phage vB_KpnS_SXFY507 was relatively broad. It has a wide range of pH tolerance and high thermal stability. The genome of phage vB_KpnS_SXFY507 was 53,122 bp in length with a G + C content of 49.1%. A total of 81 open-reading frames (ORFs) and no virulence or antibiotic resistance related genes were involved in the phage vB_KpnS_SXFY507 genome. Phage vB_KpnS_SXFY507 showed significant antibacterial activity in vitro. The survival rate of Galleria mellonella larvae inoculated with K. pneumoniae SXFY507 was 20%. The survival rate of K. pneumonia-infected G. mellonella larvae was increased from 20 to 60% within 72 h upon treatment with phage vB_KpnS_SXFY507. In conclusion, these findings indicate that phage vB_KpnS_SXFY507 has the potential to be used as an antimicrobial agent for the control of K. pneumoniae.

Polymorphisms in the ASAP1 and SP110 Genes and Its Association with the Susceptibility to Pulmonary Tuberculosis in a Mongolian Population: Tuberculosis (TB) remains one of the deadliest infectious diseases in the world. Previous genome-wide association studies suggested that single-nucleotide polymorphisms (SNPs) in some genes could indicate the susceptibility to TB in some populations. Herein, we studied the association of SNPs in the immunity-related genes, i.e., ASAP1 and SP110 genes with the susceptibility to TB in a Mongolian population in China. A case–control study was performed with 197 TB patients and 217 healthy controls. Six SNPs in ASAP1 and six SNPs in SP110 were selected for genotyping test by second-generation sequencing technique. A SNP in SP110 gene (rs722555) was identified to be associated with susceptibility to TB in the Mongolian population ( ). The T allele of rs722555 in SP110 gene was associated with a 36% increase of risk at TB (OR 1.36, 95% CI 1.03–1.81), and the CT+TT genotype of rs722555 was associated with a 74% increase of risk at TB (OR 1.74, 95% CI 1.16–2.60) in the dominant genetic model. None of SNPs in ASAP1 gene tested in this study were significantly associated with TB susceptibility, while some individuals with SNPs (rs10956514, rs4733781, rs2033059, rs12680942, rs1017281, rs1469288, and rs17285138) in the ASAP1 gene tended to have a reduced risk at TB. In conclusion, this study suggested that the rs722555 SNP in SP110 gene might be a risk factor for TB in a Mongolian population.

Antimicrobial resistance (AMR) threatens global public health and modern surgical medicine. Expression of β-lactamase genes is the major mechanism by which pathogens become antibiotic resistant. Pathogens expressing extended spectrum β-lactamases (ESBL) and carbapenemases (CP) are especially difficult to treat and are associated with increased hospitalization and mortality rates. Despite considerable effort, identification of ESBLs and CPs in a clinically relevant timeframe remains challenging. In this study, a two-dimensional AMR profiling assay strategy was developed employing panels of antibiotics (penicillins, cephamycins, oximino-cephalosporins and carbapenems) and β-lactamases inhibitors (avibactam and EDTA). The assay required the development of a novel biosensor that employed New Delhi metallo-β-lactamase-1 (NDM-1) as the sensing element. Functionally probing β-lactamase activity using substrates and inhibitors combinatorically increased the informational content that enabled the development of assays capable of simultaneous, differential identification of multiple β-lactamases expressed in a single bacterial isolate. More specifically, the assay enabled the simultaneous identification of ESBL and CP in mock samples, as well as in an engineered construct which co-expressed these β-lactamases. The NDM-1 biosensor assay was 16 times and 8 times more sensitive than the ESBL Nordmann/Dortet/Poirel (NDP) and Carba Nordmann/Poirel (NP) assays, respectively. In a retrospective study, NDM-1 biosensor assays were able to differentially identify ESBLs, metallo-CPs and serine-CPs β-lactamases in 23 clinical isolates with 100% accuracy. An assay algorithm was developed which accelerated data analytics reducing turnaround to <1 h. The assay strategy integrated with AI-based data analytics has the potential to provide physicians with a comprehensive readout of patient AMR status.