Development of an all-in-one real-time PCR assay for simultaneous detection of spotted fever group rickettsiae, severe fever with thrombocytopenia syndrome virus and hantaan virus prevalent in central China.

Central China has been reported to be one of the most important endemic areas of zoonotic infection by spotted fever group rickettsiae (SFGR), severe fever with thrombocytopenia syndrome virus (SFTSV) and hantaan virus (HTNV). Due to similar clinical symptoms, it is challenging to make a definite diagnosis rapidly and accurately in the absence of microbiological tests. In the present study, an all-in-one real-time PCR assay was developed for the simultaneous detection of nucleic acids from SFGR, SFTSV and HTNV. Three linear standard curves for determining SFGR-ompA, SFTSV-L and HTNV-L were obtained within the range of 101-106 copies/µL, with the PCR amplification efficiencies ranging from 93.46% to 96.88% and the regression coefficients R2 of >0.99. The detection limit was 1.108 copies/µL for SFGR-ompA, 1.075 copies/µL for SFTSV-L and 1.006 copies/µL for HTNV-L, respectively. Both the within-run and within-laboratory coefficients of variation on the cycle threshold (Ct) values were within the range of 0.53%-2.15%. It was also found there was no statistical difference in the Ct values between single template and multiple templates (PSFGR-ompA = 0.186, PSFTSV-L = 0.612, PHTNV-L = 0.298). The sensitivity, specificity, positive and negative predictive value were all 100% for determining SFGR-ompA and SFTSV-L, 97%, 100%, 100% and 99.6% for HTNV-L, respectively. Therefore, the all-in-one real-time PCR assay appears to be a reliable, sensitive, rapid, high-throughput and low cost-effective method to diagnose the zoonotic infection by SFGR, SFTSV and HTNV.

Prevalence of ST1049-KL5 carbapenem-resistant Klebsiella pneumoniae with a blaKPC-2 and blaNDM-1 co-carrying hypertransmissible IncM1 plasmid.

Infection caused by KPC and NDM carbapenemases co-producing Klebsiella pneumoniae (KPC_NDM_CRKP) poses serious public health concerns. Here, we elucidate the prevalence of a hypertransmissible lncM1 plasmid, pKPC_NDM, co-carrying blaKPC-2 and blaNDM-1 genes in sequence type 1049 K_locus 5 (ST1049-KL5) KPC_NDM_CRKP isolates. Genetic and clonal relatedness analyses using pulsed-field gel electrophoresis, single nucleotide polymorphism analysis and core genome multilocus sequence typing suggested clonal dissemination of ST1049-KL5 KPC_NDM_CRKP strains in our hospital. Whole genome sequencing identified an identical 76,517 bp- blaKPC-2 and blaNDM-1 genes co-carrying IncM1 plasmid pKPC_NDM and a pLVPK-like hypervirulent plasmid in all ST1049-KL5 KPC_NDM_CRKP isolates. pKPC_NDM shared 100% identity with a previously sequenced plasmid CRKP35_unnamed4, demonstrating high transferability in conjugation assay, with conjugation frequencies reaching 10-4 and 10-5 in Escherichia coli and K. pneumoniae recipients, respectively. It also maintained favorable stability and flexible compatibility, with retention rates exceeding 80% after 10 days of continuous passage, and could be compatible with pre-existing blaKPC- or blaNDM-carrying plasmids in recipient strains. This study summarizes the characteristics of KPC_NDM_CRKP outbreaks and highlights the importance of ongoing surveillance and infection control strategies to address the challenges posed by ST1049 K. pneumoniae strains.

Clinical and molecular characteristics of Klebsiella pneumoniae infection in a tertiary general hospital of Wuhan, China.

OBJECTIVES: The aim of this study was to investigate the clinical and molecular characteristics of Klebsiella pneumoniae infection from a tertiary general hospital in Wuhan, China. METHODS: From December 2019 to August 2022, 311 non-duplicate isolates of K. pneumoniae were collected from a tertiary hospital in Wuhan. These comprised 140 carbapenem-resistant K. pneumoniae (CRKP) isolates and 171 carbapenem-susceptible K. pneumoniae (CSKP) isolates. The clinical characteristics of patients with K. pneumoniae infection were retrospectively collected. Polymerase chain reaction (PCR) assays were used to identify the main carbapenem resistance genes, virulence genes and multi-locus sequence typing (MLST) profiles of the isolates, and the Galleria mellonella infection model was used to determine their virulence phenotypes. RESULTS: Independent risk factors for CRKP infection were hypertension, neurological disorders, being admitted to the intensive care unit (ICU) and prior use of antibiotics. Patient with CRKP infection had higher mortality than those with CSKP infection (23.6% vs 14.0%, P < 0.05). One hundred and two sequence types (STs) were identified among the K. pneumoniae isolates, and the most prevalent ST type was ST11 (112/311, 36.0%). All of the ST11 isolates were CRKP. Among the 112 ST11 isolates, 105 (93.8%) harboured the carbapenem resistance gene blaKPC-2 (ST11-KPC-2), and of these isolates, 78 (74.3%, 78/105) contained all of the four virulence genes, namely rmpA, rmpA2, iroN and iucA, suggesting that these genes were widespread among the isolates responsible for K. pneumoniae infections. CONCLUSION: In this study, ST11-KPC-2 was responsible for most of the K. pneumoniae infection cases. Carbapenem resistance rather than the co-occurrence of the virulence genes rmpA, rmpA2, iroN and iucA was associated with K. pneumoniae infection-related mortality during hospitalisation. Furthermore, a high proportion of ST11-KPC-2 isolates carried all of the four virulence genes.

Geometric shaping optimization of 64-APSK constellation in discrete nonlinear frequency division multiplexing systems.

We experimentally demonstrated a geometric shaped (GS) 64-ary amplitude phase shift keying (64-APSK) eigenvalue transmission. The signal is modulated on the scatter coefficient of a single eigenvalue and linear minimum mean square error (LMMSE) estimator is used to reduce the noise. The channel response is estimated by transmitting a normally distributed 64-APSK constellation through a communication link. Based on the polar coordinates distribution of the received constellation, the diameter distributions for each circle can be obtained so that circles with larger noise can obtain larger judgment width. After optimization, the experimental results show that the Q-factor gain is 1.13 dB under 22 dB received optical signal to noise ratio (OSNR) configuration and 0.88 dB after 900 km transmission compared with normally distributed APSK configuration.

Non-antibiotic methods against Pseudomonas aeruginosa include QS inhibitors: a narrative review.

The prevalence of antibiotic resistance is a growing worldwide problem in the control of pathogens, particularly negative bacteria that are resistant to antibiotics, Pseudomonas aeruginosa (PA) is one of these bacteria. The development of new effective antibiotics is time-consuming and costly, and the new antibiotics may become resistant again. Therefore, non-antibiotic clinical treatment for antibiotic-resistant PA infection is necessary and needs to be strengthened. The antibiotic resistance (AR) mechanism of PA is complex. Biofilm formation is one of the reasons why its resistance is difficult to overcome. The formation of biofilms is mainly regulated by quorum sensing (QS). QS is a mechanism by which PA increases its virulence by producing small diffusible molecules, which regulates a series of genes associated with virulence and nutrient acquisition. QS inhibitors are potions that obstruct QS systems in bacteria and destruction of virulence. This review summarizes AR mechanism of PA, Basic knowledge of QS of PA and some non-antibiotic methods for inhibiting PA, including QS inhibitors, which have potential and far-reaching significance for antibiotic-resistant PA's clinical treatment. The review helps to provide new ideas and new schemes for clinical anti-PA infection research and treatment, and has positive significance for delaying the occurrence of bacterial drug resistance and antibiotic use management.

[Role and application of programmed death protein 1 (PD-1) and its ligand PD-L1 in immune cell dysfunction in sepsis: An update].

Immunosuppression is increasingly being recognized as one of the causes of increased morbidity and mortality during sepsis. Both innate and adaptive immune system dysfunction have been shown to cause an impaired ability to eradicate the primary infection and also lead to frequent occurrence of secondary opportunistic infections. Immune checkpoint molecules, such as programmed death 1 (PD-1) and PD-1 ligand 1 (PD-L1), are up-regulated during the immunosuppressive phase of sepsis, not only on adaptive immune cells (such as T cells), but also on innate immune cells (such as macrophages, monocytes, neutrophils) as well as non-immune cells, resulting in functional changes, often with adverse sequelae. In numerous pre-clinical models of sepsis, therapeutic agents for blocking engagement of inhibitory immune checkpoints on immune cells have been shown to improve innate and adaptive immune cell functions, increase host resistance to infection and significantly improve survival.

Sparse-fast-Fourier-transform-based quick synchronization for optical direct detection orthogonal frequency division multiplexing systems.

Orthogonal frequency division multiplexing (OFDM) has always been a promising candidate for optical access networks. However, it is very sensitive to synchronization errors and requires complex digital signal processing to eliminate this influence, thus increasing the computation complexity, delay, and system cost, which hampers its applications in cost-sensitive and low-latency scenarios of future optical access networks. To deal with this issue, a sparse-fast-Fourier-transform (FFT)-based quick synchronization algorithm for optical direct detection OFDM systems is proposed and demonstrated with greatly reduced computation complexity. Detailed simulations and experimental verifications along 50 km standard single-mode-fiber transmission prove the efficiency, accuracy, and feasibility of the sparse-FFT-based synchronization technique in cost- and delay-sensitive applications for next-generation optical access networks.