The effectiveness of Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-Cas14a1, widely utilized for pathogenic microorganism detection, has been limited by the requirement of a protospacer adjacent motif (PAM) on the target DNA strands. To overcome this limitation, this study developed a Single Primer isothermal amplification integrated-Cas14a1 biosensor (SPCas) for detecting Salmonella typhi that does not rely on a PAM sequence. The SPCas biosensor utilizes a novel primer design featuring an RNA-DNA primer and a 3\'-biotin-modified primer capable of binding to the same single-stranded DNA (ssDNA) in the presence of the target gene. The RNA-DNA primer undergoes amplification and is blocked at the biotin-modified end. Subsequently, strand replacement is initiated to generate ssDNA assisted by RNase H and Bst enzymes, which activate the trans-cleavage activity of Cas14a1 even in the absence of a PAM sequence. Leveraging both cyclic chain replacement reaction amplification and Cas14a1 trans-cleavage activity, the SPCas biosensor exhibits a remarkable diagnostic sensitivity of 5 CFU/mL. Additionally, in the assessment of 20 milk samples, the SPCas platform demonstrated 100% diagnostic accuracy, which is consistent with the gold standard qPCR. This platform introduces a novel approach for developing innovative CRISPR-Cas-dependent biosensors without a PAM sequence.

Multiple TonB dependent transporters (TBDTs) contribute to bacterial virulence due to the importance roles that their substrates play in bacterial growth, and possess vaccine potential. A putative TBDT, YncD, had been identified as one of in vivo induced antigens during human infection of typhoid fever, and is required for the pathogenicity of Salmonella enterica Serovar Typhi. The present study was aimed to determine the function and immunogenicity of YncD. Homologous recombination method was used to construct an yncD-deletion mutant and cirA-iroN-fepA-deletion mutant from the wild-type S. Typhi Ty2. The growth of mutants and the wild-type strain were assessed in iron-deficient medium, as well as in human macrophage cells. Recombinant YncD protein was expressed and purified using Ni-NTA affinity chromatography and anion exchange. A mouse model was then used to evaluate the immunogenicity and protection efficacy of the recombinant YncD. Antibody levels, serum bactericidal efficiency, passive immune protection, opsonophagocysis were assayed to analyse the immunoprotection mechanism of the recombinant YncD. Our results showed that YncD is associated with the iron-uptake of S. Typhi. The yncD-deletion mutant displayed impaired growth in iron-deficient medium, comparable to that the cirA-iroN-fepA-deletion mutant did. The mutation of yncD markedly decreased bacterial growth within human macrophage cells. Moreover, subcutaneous immunization of mice with recombinant YncD elicited high levels of specific anti-YncD IgG, IgG1 and IgG2a, which protected the immunized mice against the intraperitoneal challenge of S. Typhi, and decreased bacterial burdens in the livers and spleens of the infected mice. Passive immunization using the immunized sera also efficiently protected the mice from the challenge of S. Typhi. Moreover, the immunized sera enhanced in vitro bactericidal activity of complement, and opsonophagocytosis. Our results showed that YncD displays a role in the iron-uptake of S. Typhi and possesses immunogenicity.

Objective: To analyze the incidence trend and epidemiological characteristics of typhoid fever in Fujian Province from 2011 to 2022, and understand the high-incidence population and hotspot areas, and provide evidences to develop more targeted prevention and control measures. Methods: The surveillance data of typhoid fever during 2011-2022 in Fujian Province were obtained from the National Disease Reporting Information System and analyzed with SAS 9.4. The spatial autocorrelation analysis of typhoid fever incidence at county/district levels was performed with ArcGlS 10.8. Results: A total of 5 126 cases of typhoid fever were reported in Fujian Province from 2011 to 2022, with an average annual incidence rate of 1.10/100 000. The average annual incidence rate was 0.96/100 000 from 2011 to 2015, 1.49/100 000 from 2016 to 2019, and 0.81/100 000 from 2020 to 2022. The disease occurred all the year round, with high epidemic season from May to September. A total of 23.59% (1 209/5 126) of the cases occurred at the age of 0-4, and 9.62% (493/5 126) at the age of 5-9. The male to female ratio of the cases was 0.97∶1 (2 524∶2 602) for the whole population, 1.19∶1 (925∶777) for people under 10 years old, 0.75∶1 (1 060∶1 404) for people between 10 and 54 years old, and 1.28∶1 (539∶421) for people over 55 years old. Cases in Ningde City accounted for 30.65% (1 571/5 126) of the total cases. Most hotspots were occurred in Ningde City. Recurrent and clustered cases were found in family members. Conclusions: Typhoid fever was prevalent at a low level in Fujian Province during 2011-2022, indicating that strengthening the prevention and control measures should target key areas and populations. The incidence of typhoid fever in Fujian Province showed spatial aggregation phenomenon, and most cases gathered in Ningde City. Intensive study for the influencing factors of spatial clustering should be conducted.
目的： 分析2011-2022年福建省伤寒发病趋势和流行特征，探索高发人群和热点区域，为制定针对性防控措施提供科学依据。 方法： 从中国疾病预防控制信息系统收集福建省2011-2022年伤寒监测资料，采用SAS 9.4软件进行统计学分析，采用ArcGIS 10.8软件对各县（区）发病率进行空间自相关分析。 结果： 2011-2022年福建省伤寒共报告发病5 126例，年均发病率为1.10/10万。年均发病率在2011-2015、2016-2019和2020-2022年分别为0.96/10万、1.49/10万和0.81/10万。全年均有发病，高发季节为5-9月。0~4岁和5~9岁年龄组发病数分别占23.59%（1 209/5 126）和9.62%（493/5 126）。全人群的男女性别比为0.97∶1（2 524∶2 602），<10、10~54和≥55岁年龄组男女性别比分别为1.19∶1（925∶777）、0.75∶1（1 060∶1 404）、1.28∶1（539∶421）。宁德市发病占福建省的30.65%（1 571/5 126）；发病热点区域主要集中在宁德市。存在再次发病和家庭成员续发现象。 结论： 2011-2022年福建省伤寒呈低水平流行，应针对重点地区和重点人群加强防控措施；发病存在空间聚集性，宁德市是主要的聚集区域，应深入调研其空间聚集的影响因素。.

Typhoid fever is caused by Salmonella enterica serotype Typhi (Salmonella Typhi). Syndromes in patients vary from asymptomatic carriers to severe or death outcomes, which are frequently reported in African and Southeast Asian countries. It is one of the most common waterborne transmission agents, whose transmission is likely impacted by climate change. Here, we claimed the evidence and consequences of climate-related foodborne and waterborne diseases have increased and provided possible mitigations against Typhoidal Salmonella dissemination.

BACKGROUND: Typhoid fever is a fatal disease in humans that is caused by Salmonella typhi. S. typhi infections need immediate antibiotic therapy, and their extensive use has led to multidrug-resistant (MDR) pathogens. The use of bacteriophages is becoming a new way to treat these resistant bacteria. This research was directed to bacteriophage isolation against S. typhi and to determine phage-antibiotic synergism.
OBJECTIVE: To isolate bacteriophages targeting S. typhi, the causative agent of typhoid fever, and investigate their potential synergistic effects when combined with antibiotics.
METHODS: A cross-sectional study.
METHODS: The Widal test was positive; twenty diarrheal stool samples were taken, and for confirmation of S. typhi, different biochemical tests were performed. The disc-diffusion technique was used to determine antimicrobial resistance, and the double agar overlay method was used for bacteriophage isolation from sewage water against S. typhi. To test antibiotic-phage synergism, the S. typhi bacteria was treated by phages together with varying antibiotic concentrations.
RESULTS: Eleven samples were positive for S. typhi with black colonies on SS-agar. These were catalase and MR positive with alkali butt on TSI. Clear plaques were observed after the agar overlay. Isolated phages were stable at various pH and temperature levels. Synergism was observed on agar plate. The zone was enlarged when phages were combined with bacterial lawn culture and ciprofloxacin disk. Bacterial growth inhibition had a significant p-value of 0.03 in titration plates, with the phage-ciprofloxacin combination being more effective than the phage and antibiotic alone.
CONCLUSIONS: The study highlights the synergistic effects of isolated bacteriophages with antibiotics, which are not only effective against S. typhi infection but also decrease antibiotic resistance.

BACKGROUND: Typhoid fever, caused by Salmonella enterica serovar Typhi, is a significant public health concern due to the escalating of antimicrobial resistance (AMR), with limited treatment options for extensively drug-resistant (XDR) S. Typhi strains pose a serious threat to disease management and control. This study aimed to investigate the genomic characteristics, epidemiology and AMR genes of XDR S. Typhi strains from typhoid fever patients in Pakistan.
METHODS: We assessed 200 patients with enteric fever symptoms, confirming 65 S. Typhi cases through culturing and biochemical tests. Subsequent antimicrobial susceptibility testing revealed 40 cases of extensively drug-resistant (XDR) and 25 cases of multi-drug resistance (MDR). Thirteen XDR strains were selected for whole-genome sequencing, to analyze their sequence type, phylogenetics, resistance genes, pathogenicity islands, and plasmid sequences using variety of data analysis resources. Pangenome analysis was conducted for 140 XDR strains, including thirteen in-house and 127 strains reported from other regions of Pakistan, to assess their genetic diversity and functional annotation.
RESULTS: MLST analysis classified all isolates as sequence type 1 (ST-1) with 4.3.1.1. P1 genotype characterization. Prophage and Salmonella Pathogenicity Island (SPI) analysis identified intact prophages and eight SPIs involved in Salmonella\'s invasion and replication within host cells. Genome data analysis revealed numerous AMR genes including dfrA7, sul1, qnrS1, TEM-1, Cat1, and CTX-M-15, and SNPs associated with antibiotics resistance. IncY, IncQ1, pMAC, and pAbTS2 plasmids, conferring antimicrobial resistance, were detected in a few XDR S. Typhi strains. Phylogenetic analysis inferred a close epidemiological linkage among XDR strains from different regions of Pakistan. Pangenome was noted closed among these strains and functional annotation highlighted genes related to metabolism and pathogenesis.
CONCLUSIONS: This study revealed a uniform genotypic background among XDR S. Typhi strains in Pakistan, signifying a persistence transmission of a single, highly antibiotic-resistant clone. The closed pan-genome observed underscores limited genetic diversity and highlights the importance of genomic surveillance for combating drug-resistant typhoid infections.

Here, we report a case of blood culture-confirmed typhoid fever, rhabdomyolysis, and multiple organ damage that arrived in our country from overseas. A 23-year-old male patient presented at our hospital with fever and muscle pain; the condition progressed rapidly. Six days after the onset of symptoms, the patient developed rhabdomyolysis and liver/kidney damage; levels of creatine kinase (CK; maximum peak: 729,869 U/L) and myoglobin (> 3,000 ng/mL) were extremely high, although the extent of renal damage was relatively mild. Blood culture showed Salmonella typhi. The patient received a combination of meropenem and levofloxacin anti-infective therapy, as well as fluid and nutritional metabolic support. He gradually recovered and was discharged after two negative blood cultures. This case highlights the fact that typhoid-induced rhabdomyolysis is a serious, life-threatening disease and that the levels of CK and myoglobin are useful indicators for evaluating typhoid-induced rhabdomyolysis. Clinicians should remain vigilant regarding travel-related illnesses associated with enteric fever.

BACKGROUND: Intestinal infectious diseases (IIDs) are a significant public health issue in China, and the incidence and distribution of IIDs vary greatly by region and are affected by various factors. This study aims to describe the spatio-temporal trends of IIDs in the Chinese mainland and investigate the association between socioeconomic and meteorological factors with IIDs.
METHODS: In this study, IIDs in mainland China from 2006 to 2017 was analyzed using data obtained from the China Center for Disease Control and Prevention. Spatio-temporal mapping techniques was employed to visualize the spatial and temporal distribution of IIDs. Additionally, mean center and standard deviational ellipse analyses were utilized to examine the spatial trends of IIDs. To investigate the potential associations between IIDs and meteorological and socioeconomic variables, spatiotemporal zero-inflated Poisson and negative binomial models was employed within a Bayesian framework.
RESULTS: During the study period, the occurrence of most IIDs has dramatically reduced, with uneven reductions in different diseases. Significant regional differences were found among IIDs and influential factors. Overall, the access rate to harmless sanitary toilets (ARHST) was positively associated with the risk of cholera (RR: 1.73, 95%CI: 1.08-2.83), bacillary dysentery (RR: 1.32, 95%CI: 1.06-1.63), and other intestinal infectious diseases (RR: 1.88, 95%CI: 1.52-2.36), and negatively associated with typhoid fever (RR: 0.66, 95%CI: 0.51-0.92), paratyphoid fever (RR: 0.71, 95%CI: 0.55-0.92). Urbanization is only associated with hepatitis E (RR: 2.48, 95%CI: 1.12-5.72). And GDP was negatively correlated with paratyphoid fever (RR: 0.82, 95%CI: 0.70-0.97), and bacillary dysentery (RR: 0.77, 95%CI: 0.68-0.88), and hepatitis A (RR: 0.84, 95%CI: 0.73-0.97). Humidity showed positive correlation with some IIDs except for amoebic dysentery (RR: 1.64, 95%CI: 1.23-2.17), while wind speed showed a negative correlation with most IIDs. High precipitation was associated with an increased risk of typhoid fever (RR: 1.52, 95%CI: 1.09-2.13), and high temperature was associated with an increased risk of typhoid fever (RR: 2.82, 95%CI: 2.06-3.89), paratyphoid fever (RR: 2.79, 95%CI: 2.02-3.90), and HMFD (RR: 1.34, 95%CI: 1.01-1.77).
CONCLUSIONS: This research systematically and quantitatively studied the effect of socioeconomic and meteorological factors on IIDs, which provided causal clues for future studies and guided government planning.

OBJECTIVE: Typhoid fever is a life-threatening disease caused by Salmonella enterica serovar Typhi, resulting in a significant disease burden across developing countries. Historically, China was very much close to the global epicenter of typhoid, but the role of typhoid transmission within China and among epicenter remains overlooked in previous investigations. By using newly produced genomics on a national scale, we clarify the complex local and global transmission history of such a notorious disease agent in China spanning the most recent five decades, which largely undermines the global public health network.

Recently, attention has focused on the impact of global climate change on infectious diseases. Storm flooding is an extreme weather phenomenon that not only impacts the health of the environment but also worsens the spread of pathogens. This poses a significant challenge to public health security. However, there is still a lack of research on how different levels of storm flooding affect susceptible enteric infectious diseases over time.
Data on enteric infectious diseases, storm flooding events, and meteorology were collected for Changsha, Hunan Province, between 2016 and 2020. The Wilcoxon Rank Sum Test was used to identify the enteric infectious diseases that are susceptible to storm flooding. Then, the lagged effects of different levels of storm flooding on susceptible enteric infectious diseases were analyzed using a distributed lag nonlinear model.
There were eleven storm flooding events in Changsha from 2016 to 2020, concentrated in June and July. 37,882 cases of enteric infectious diseases were reported. During non-flooding days, the daily incidence rates of typhoid/paratyphoid and bacillary dysentery were 0.3/100,000 and 0.1/100,000, respectively. During flooding days, the corresponding rates increased to 2.0/100,000 and 0.8/100,000, respectively. The incidence rates of both diseases showed statistically significant differences between non-flooding and flooding days. Correlation analysis shows that the best lags for typhoid/paratyphoid and bacillary dysentery relative to storm flooding events may be 1 and 3 days. The results of the distributed lag nonlinear model showed that typhoid/paratyphoid had the highest cumulative RR values of 2.86 (95% CI: 1.71-4.76) and 8.16 (95% CI: 2.93-22.67) after 4 days of general flooding and heavy flooding, respectively; and bacillary dysentery had the highest cumulative RR values of 1.82 (95% CI: 1.40-2.35) and 3.31 (95% CI: 1.97-5.55) after 5 days of general flooding and heavy flooding, respectively.
Typhoid/paratyphoid and bacillary dysentery are sensitive enteric infectious diseases related to storm flooding in Changsha. There is a lagging effect of storm flooding on the onset of typhoid/paratyphoid and bacillary dysentery, with the best lagging periods being days 1 and 3, respectively. The cumulative risk of typhoid/paratyphoid and bacillary dysentery was highest at 4/5 days lag, respectively. The higher of storm flooding, the higher the risk of disease, which suggests that the authorities should take appropriate preventive and control measures before and after storm flooding.