Bispecific antibodies (BsAbs) recognize two different epitopes. This dual specificity opens up a wide range of applications, including redirecting T cells to tumor cells, blocking two different signaling pathways simultaneously, dual targeting of different disease mediators, and delivering payloads to targeted sites. The approval of catumaxomab (anti-EpCAM and anti-CD3) and blinatumomab (anti-CD19 and anti-CD3) has become a major milestone in the development of bsAbs. Currently, more than 60 different bsAb formats exist, some of them making their way into the clinical pipeline. This review summarizes diverse formats of bsAbs and their clinical applications and sheds light on strategies to optimize the design of bsAbs.

Combating plasmid-mediated carbapenem resistance is essential to control and prevent the dissemination of carbapenem-resistant Enterobacteriaceae (CRE). Here, we conducted a proof-of-concept study to demonstrate that CRISPR-Cas9-mediated resistance gene and plasmid curing can effectively resensitize CRE to carbapenems. A novel CRISPR-Cas9-mediated plasmid-curing system (pCasCure) was developed and electrotransferred into various clinical CRE isolates. The results showed that pCasCure can effectively cure bla _KPC , bla _NDM , and bla _OXA-48 in various Enterobacteriaceae species of Klebsiella pneumoniae , Escherichia coli , Enterobacter hormaechei , Enterobacter xiangfangensis , and Serratia marcescens clinical isolates, with a >94% curing efficiency.

Many studies about serum IgG4 for the diagnosis of IgG4-related disease (IgG4-RD) have been reported. However, these studies had relatively small sample sizes and the diagnostic accuracy values varied much between them.The aim of this study was to perform a meta-analysis to evaluate the diagnostic value of serum IgG4 for IgG4-RD.We conducted a search of relevant articles using MEDLINE, EMBASE, Web of Science, SCOPUS, and Cochrane Library databases published before December 2015.Studies those assessed the diagnostic accuracy of serum IgG4 for IgG4-RD and those provided the cut-off value for serum IgG4 were included.Data were synthesized using the random-effect model. Statistical analysis was performed using STATA with the MIDAS module and Meta-DiSc 1.4 software.A total of 9 case-control studies were analyzed, which included 1235 patients with IgG4-RD and 5696 overall controls. The pooled estimate, for a cut-off value ranged from 135 to 144 mg/dL, produced a sensitivity of 87.2% (95% CI, 85.2-89.0%) and a specificity of 82.6% (95% CI, 81.6-83.6%). The positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) were 6.48 (95% CI, 3.98-10.57), 0.14 (95% CI, 0.09-0.21), and 45.15 (95% CI, 23.41-87.06), respectively. The area under the curve (AUC) of the summary receiver operating characteristic curve (SROC) was 0.94 (0.92-0.96). When a cut-off value of 2-fold the upper limit of normal was used (ranged from 270 to 280 mg/dL), the pooled sensitivity was 63% (95% CI, 60.0-66.0%), and the specificity was 94.8% (95% CI, 94.1-95.4%). The PLR, NLR, and DOR were 13.3 (95% CI, 7.39-24.0), 0.41 (95% CI, 0.29-0.58) and 33.42 (95% CI, 13.88-80.43), respectively. The AUC of the SROC was 0.92 (0.90-0.94).Only a relatively small number of studies were included, and significant heterogeneity was observed in this meta-analysis.Serum IgG4 is a modestly effective marker to diagnose IgG4-RD. Doubling the cut-off value for IgG4 could not improve the overall test characteristics. A high specificity inevitably accompanies with a significant sacrifice in sensitivity.

Objective: The emergence of carbapenem-resistant and hypervirulent Klebsiella pneumoniae (CR-hvKp) strains poses a significant public threat, and effective antimicrobial therapy is urgently needed. Recent studies indicated that apramycin is a potent antibiotic with good activity against a range of multi-drug resistant pathogens. In this study, we evaluated the in vitro activity of apramycin against clinical CR-hvKp along with carbapenem-resistant non-hvKp (CR-non-hvKp) isolates. Methods: Broth microdilution method was used to evaluate the in vitro activities of apramycin, gentamicin, amikacin, imipenem, meropenem, doripenem, ertapenem and other comparator “last-resort” antimicrobial agents, including ceftazidime-avibactam, colistin and tigecycline, against eighty-four CR-hvKp and forty CR-non-hvKp isolates collected from three Chinese hospitals. Multilocus Sequence typing (MLST), molecular capsule typing (wzi sequencing) and antimicrobial resistance genes were examined by PCR and Sanger sequencing. Pulsed-field gel electrophoresis and next generation sequencing were conducted on selected isolates. Results: Among the 84 CR-hvKp isolates, 97.6, 100, 97.6, and 100% were resistant to imipenem, meropenem, doripenem and ertapenem, respectively. Apramycin demonstrated an MIC₅₀/MIC₉₀ of 4/8 μg/mL against the CR-hvKp isolates. In contrast, the MIC₅₀/MIC₉₀ for amikacin and gentamicin were >64/>64 μg/mL. All CR-hvKp isolates were susceptible to ceftazidime-avibactam, colistin and tigecycline with the MIC₅₀/MIC₉₀ values of 0.5/1, 0.25/0.5, 1/1, respectively. For CR-non-hvKp, The MIC_50/90 values for apramycin, gentamicin and amikacin were 2/8, >64/>64, and >64/>64 μg/mL, respectively. There were no statistical significance in the resistance rates of antimicrobial agents between CR-hvKp and CR-non-hvKp groups (p > 0.05). Genetic analysis revealed that all CR-hvKp isolates harbored bla_KPC–2, and 94% (n = 79) belong to the ST11 high-risk clone. 93.6% (44/47) of amikacin or gentamicin resistant strains carried 16S rRNA methyltransferases gene rmtB. Conclusion: Apramycin demonstrated potent in vitro activity against CR-hvKp isolates, including those were resistant to amikacin or gentamicin. Further studies are needed to evaluate the applicability of apramycin to be used as a therapeutic antibiotic against CR-hvKp infections.

Background: Carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP) co-producing bla_KPC and bla_NDM poses a serious threat to public health. This study aimed to investigate the mechanisms underlying the resistance and virulence of CR-hvKP isolates collected from a Chinese hospital, with a focus on bla_KPC and bla_NDM dual-positive hvKP strains. Methods: Five CR-hvKP strains were isolated from a teaching hospital in China. Antimicrobial susceptibility and plasmid stability testing, plasmid conjugation, pulsed-field gel electrophoresis, and whole-genome sequencing (WGS) were performed to examine the mechanisms of resistance and virulence. The virulence of CR-hvKP was evaluated through serum-killing assay and Galleria mellonella lethality experiments. Phylogenetic analysis based on 16 highly homologous carbapenem-resistant K. pneumoniae (CRKP) producing KPC-2 isolates from the same hospital was conducted to elucidate the potential evolutionary pathway of CRKP co-producing NDM and KPC. Results: WGS revealed that five isolates individually carried three unique plasmids: an IncFIB/IncHI1B-type virulence plasmid, IncFII/IncR-type plasmid harboring KPC-2 and IncC-type plasmid harboring NDM-1. The conjugation test results indicated that the transference of KPC-2 harboring IncFII/IncR-type plasmid was unsuccessful on their own, but could be transferred by forming a hybrid plasmid with the IncC plasmid harboring NDM. Further genetic analysis confirmed that the pJNKPN26-KPC plasmid was entirely integrated into the IncC-type plasmid via the copy-in route, which was mediated by TnAs1 and IS26. Conclusion: KPC-NDM-CR-hvKP likely evolved from a KPC-2-CRKP ancestor and later acquired a highly transferable bla_NDM-1 plasmid. ST11-KL64 CRKP exhibited enhanced plasticity. The identification of KPC-2-NDM-1-CR-hvKP highlights the urgent need for effective preventive strategies against aggravated accumulation of resistance genes.

Tigecycline serves as one of the last-resort antibiotics to treat severe infections caused by carbapenem-resistant Enterobacterales. Recently, a novel plasmid-mediated resistance-nodulation-division (RND)-type efflux pump gene cluster, TmexCD1-ToprJ1, and its variants, TmexCD2-ToprJ2 and TmexCD3-ToprJ3, encoding tetracyclines and tigecycline resistance, were revealed. In this study, we reported three TmexCD2-ToprJ2-harboring Klebsiella species strains, collected from two teaching tertiary hospitals in China, including one K. quasipneumoniae, one K. variicola, and one K. michiganensis. The three strains were characterized by antimicrobial susceptibility testing (AST), conjugation assay, WGS, and bioinformatics analysis. AST showed that K. variicola and K. quasipneumoniae strains were resistant to tigecycline with MIC values of 4μg/ml, whereas the K. michiganensis was susceptible to tigecycline with an MIC value of 1μg/ml. The TmexCD2-ToprJ2 clusters were located on three similar IncHI1B plasmids, of which two co-harbored the metallo-β-lactamase gene bla_NDM-1. Conjugation experiments showed that all three plasmids were capable of self-transfer via conjugation. Our results showed, for the first time, that this novel plasmid-mediated tigecycline resistance mechanism TmexCD2-ToprJ2 has spread into different Klebsiella species, and clinical susceptibility testing may fail to detect. The co-occurrence of bla_NDM-1 and TmexCD2-ToprJ2 in the same plasmid is of particular public health concern as the convergence of “mosaic” plasmids can confer both tigecycline and carbapenem resistance. Its further spread into other clinical high-risk Klebsiella clones will likely exacerbate the antimicrobial resistance crisis. A close monitoring of the dissemination of TmexCD-ToprJ encoding resistance should be considered.