Typhoid and paratyphoid fever

Convergent synthesis of the pentasaccharide repeating unit corresponding to the cell wall O-polysaccharide of Salmonella milwaukee (group U) O:43 strain

Synthesis of the pentasaccharide repeating unit of the cell O-polysaccharide produced by Salmonella milwaukee O:43 strain (group U) has been achieved in very good yield adopting a convergent stereoselective [3 + 2] block glycosylation strategy. Thioglycosides and glycosyl trichloroacetimidate derivative were used as glycosyl donors in the presence of a combination of N-iodosuccinimide (NIS) and trimethylsilyl trifluoromethanesulfonate (TMSOTf) as thiophilic activator and TMSOTf as trichloroacetimidate activator respectively. The stereochemical outcome of all glycosylation reactions was excellent.

Characterization, genome analysis, and therapeutic evaluation of a novel Salmonella phage vB_SalS_JNS02: a candidate bacteriophage for phage therapy

Phage therapy is gaining momentum as an alternative to antibiotics in the treatment of salmonellosis caused by Salmonella. In this study, a novel Salmonella phage, vB_SalS_JNS02, was isolated successfully from poultry farms in Shandong, China. The biological characteristics of vB_SalS_JNS02 were analysed, which revealed a short latent period of approximately 10 min and a burst size of 110 PFU/cell. Moreover, vB_SalS_JNS02 exhibited remarkable stability across a wide pH range (pH 3-12) and temperatures ranging from 30 to 80°C. Genome sequencing analysis provided valuable insights into the genetic composition of vB_SalS_JNS02, which consists of a double-stranded DNA genome that spans 42,450 base pairs and has a G + C content of 49.4%. Of significant importance, the genomic sequence of vB_SalS_JNS02 did not contain any genes related to lysogenicity, virulence, or antibiotic resistance. The phage's efficacy was evaluated in a larval challenge study. Treatment with the phage resulted in increased survival of Galleria mellonella larvae (100, 70, and 85%) (MOI 0.1) in the prophylactic treatment, co-infection treatment, and remedial treatment experiments, respectively. Another in vivo experiment investigated the potential application of the phage in broiler chickens and revealed that a single oral dose of vB_SalS_JNS02 (108 PFU/mL, 100 µL/chick) administered 3 h after S. enteritidis oral administration provided effective protection. The introduction of bacteriophage not only enhances the production of secretory immunoglobulin A (sIgA), but also induces alterations in the composition of the gut microbial community. Phage therapy increases the relative abundance of beneficial bacteria, which helps to maintain intestinal barrier homeostasis. However, it is unable to fully restore the disrupted intestinal microbiome caused by S. enteritidis infection. Importantly, no significant adverse effects were observed in the animal subjects following oral administration of the phage, and our findings highlight vB_SalS_JNS02 is a hopeful candidate as a promising tool to target Salmonella infections in poultry.

The frequency and associated factors of typhoid carriage in patients undergoing cholecystectomy for gallbladder disease in Pakistan: A cross-sectional study

BACKGROUND

Enteric fever is caused by Salmonella enterica serovars Typhi (S. Typhi) and Paratyphi A, B, and C. It continues to be a significant cause of morbidity and mortality worldwide. In highly endemic areas, children are disproportionately affected, and antimicrobial resistance reduces therapeutic options. It is estimated that 2-5% of enteric fever patients develop chronic asymptomatic infection. These carriers may act as reservoirs of infection; therefore, the prospective identification and treatment of carriers are critical for long-term disease control. We aimed to find the frequency of Salmonella Typhi carriers in patients undergoing cholecystectomy. We also compared the detection limit of culturing versus qPCR in detecting S. Typhi, performed a geospatial analysis of the carriers identified using this study, and evaluated the accuracy of anti-Vi and anti-YncE in identifying chronic typhoid carriage.

METHODS

We performed a cross-sectional study in two centers in Pakistan. Gallbladder specimens were subjected to quantitative PCR (qPCR) and serum samples were analyzed for IgG against YncE and Vi by ELISA. We also mapped the residential location of those with a positive qPCR result.

FINDINGS

Out of 988 participants, 3.4% had qPCR-positive gallbladder samples (23 S. Typhi and 11 S. Paratyphi). Gallstones were more likely to be qPCR positive than bile and gallbladder tissue. Anti-Vi and YncE were significantly correlated (r = 0.78 p<0.0001) and elevated among carriers as compared to qPCR negative controls, except for anti-Vi response in Paratyphi A. But the discriminatory values of these antigens in identifying carriers from qPCR negative controls were low.

CONCLUSION

The high prevalence of typhoid carriers observed in this study suggests that further studies are required to gain information that will help in controlling future typhoid outbreaks in a superior manner than they are currently being managed.

Cost-effectiveness and public health impact of typhoid conjugate vaccine introduction strategies in Bangladesh

PURPOSE

Typhoid fever causes substantial morbidity and mortality in Bangladesh. The government of Bangladesh plans to introduce typhoid conjugate vaccines (TCV) in its expanded program on immunization (EPI) schedule. However, the optimal introduction strategy in addition to the costs and benefits of such a program are unclear.

METHODS

We extended an existing mathematical model of typhoid transmission to integrate cost data, clinical incidence data, and recently conducted serosurveys in urban, semi-urban, and rural areas. In our primary analysis, we evaluated the status quo (i.e., no vaccination) and eight vaccine introduction strategies including routine and 1-time campaign strategies, which differed by age groups targeted and geographic focus. Model outcomes included clinical incidence, seroincidence, deaths, costs, disability-adjusted life years (DALYs), and incremental cost-effectiveness ratios (ICERs) for each strategy. We adopted a societal perspective, 10-year model time horizon, and 3 % annual discount rate. We performed probabilistic, one-way, and scenario sensitivity analyses including adopting a healthcare perspective and alternate model time horizons.

RESULTS

We projected that all TCV strategies would be cost saving compared to the status quo. The preferred strategy was a nationwide introduction of TCV at 9-12 months of age with a single catch-up campaign for children ages 1-15, which was cost saving compared to all other strategies and the status quo. In the 10 years following implementation, we projected this strategy would avert 3.77 million cases (95 % CrI: 2.60 - 5.18), 11.31 thousand deaths (95 % CrI: 3.77 - 23.60), and save $172.35 million (95 % CrI: -14.29 - 460.59) compared to the status quo. Our findings were broadly robust to changes in parameter values and willingness-to-pay thresholds.

CONCLUSIONS

We projected that nationwide TCV introduction with a catch-up campaign would substantially reduce typhoid incidence and very likely be cost saving in Bangladesh.

Clinical and antimicrobial susceptibility profile of typhoid fever in children in the era of antibiotic resistance

Enteric fever remains a significant public health problem in low- and middle-income countries with further challenges from emerging antimicrobial resistance. Our prospective study evaluated the current clinical and antimicrobial susceptibility profile of enteric fever in 88 children and compared it to previously established literature. Enteric fever usually presents with nonspecific signs and symptoms, with predominant respiratory complaints. A paradigm shift in the antimicrobial sensitivity pattern has been noted, with increasing resistance for first-line antibiotics and older antibiotics such as ampicillin, cotrimoxazole, and chloramphenicol showing good sensitivity. Thus, the introduction of the latter merits consideration.

Typhoid Conjugate Vaccine: A Boon for Endemic Regions

Typhoid fever has the highest disease burden in countries in low- and middle-income countries, primarily located in Asia and Sub-Saharan Africa. Previous typhoid vaccines such as the live attenuated typhoid (Ty21a) vaccine and Vi (virulence) capsular polysaccharide vaccine had the limitation that they could not be administered with other standard childhood immunizations and were ineffective in children under two years of age. To address these shortcomings of the previous vaccines, typhoid conjugate vaccines (TCVs) were developed and prequalified by the World Health Organization. Cross-reacting material and tetanus toxoid are widely used as carrier proteins in TCVs. According to various studies, TCV has higher efficacy, has a more extended protection period, and is safe and immunogenic in infants as young as six months. This review article aims to comprehensively appraise the data available on TCVs' efficacy, duration of protection, safety, and immunogenicity in endemic regions.

Punicalagin, a pomegranate polyphenol sensitizes the activity of antibiotics against three MDR pathogens of the Enterobacteriaceae

BACKGROUND

Multidrug resistance (MDR) in the family Enterobacteriaceae is a perniciously increasing threat to global health security. The discovery of new antimicrobials having the reversing drug resistance potential may contribute to augment and revive the antibiotic arsenal in hand. This study aimed to explore the anti-Enterobacteriaceae capability of bioactive polyphenols from Punica granatum (P. granatum) and their co-action with antibiotics against clinical isolates of Enterobacteriaceae predominantly prevalent in South Asian countries.

METHODS

The Kandhari P. granatum (Pakistani origin) extracts were tested for anti-Enterobacteriaceae activity by agar well diffusion assay against MDR Salmonella enterica serovar Typhi, serovar Typhimurium and Escherichia coli. Predominant compounds of active extract were determined by mass spectrometry and screened for bioactivity by agar well diffusion and minimum inhibitory concentration (MIC) assay. The active punicalagin was further evaluated at sub-inhibitory concentrations (SICs) for coactivity with nine conventional antimicrobials using a disc diffusion assay followed by time-kill experiments that proceeded with SICs of punicalagin and antimicrobials.

RESULTS

Among all P. granatum crude extracts, pomegranate peel methanol extract showed the largest inhibition zones of 25, 22 and 19 mm, and the MICs as 3.9, 7.8 and 7.8 mg/mL for S. typhi, S. typhimurium and E. coli, respectively. Punicalagin and ellagic acid were determined as predominant compounds by mass spectrometry. In plate assay, punicalagin (10 mg/mL) was active with hazy inhibition zones of 17, 14, and 13 mm against S. typhi, S. typhimurium and E. coli, respectively. However, in broth dilution assay punicalagin showed no MIC up to 10 mg/mL. The SICs 30 μg, 100 μg, and 500 μg of punicalagin combined with antimicrobials i.e., aminoglycoside, β-lactam, and fluoroquinolone act in synergy against MDR strains with % increase in inhibition zone values varying from 3.4 ± 2.7% to 73.8 ± 8.4%. In time-kill curves, a significant decrease in cell density was observed with the SICs of antimicrobials/punicalagin (0.03-60 μg/mL/30, 100, 500 μg/mL of punicalagin) combinations.

CONCLUSIONS

The P. granatum peel methanol extract exhibited antimicrobial activity against MDR Enterobacteriaceae pathogens. Punicalagin, the bacteriostatic flavonoid act as a concentration-dependent sensitizing agent for antimicrobials against Enterobacteriaceae. Our findings for the therapeutic punicalagin-antimicrobial combination prompt further evaluation of punicalagin as a potent activator for drugs, which otherwise remain less or inactive against MDR strains.

Defying the odds: Determinants of the antimicrobial response of Salmonella Typhi and their interplay

Salmonella Typhi, the invasive serovar of S. enterica subspecies enterica, causes typhoid fever in healthy human hosts. The emergence of antibiotic-resistant strains has consistently challenged the successful treatment of typhoid fever with conventional antibiotics. Antimicrobial resistance (AMR) in Salmonella is acquired either by mutations in the genomic DNA or by acquiring extrachromosomal DNA via horizontal gene transfer. In addition, Salmonella can form a subpopulation of antibiotic persistent (AP) cells that can survive at high concentrations of antibiotics. These have reduced the effectiveness of the first and second lines of antibiotics used to treat Salmonella infection. The recurrent and chronic carriage of S. Typhi in human hosts further complicates the treatment process, as a remarkable shift in the immune response from pro-inflammatory Th1 to anti-inflammatory Th2 is observed. Recent studies have also highlighted the overlap between AP, persistent infection (PI) and AMR. These incidents have revealed several areas of research. In this review, we have put forward a timeline for the evolution of antibiotic resistance in Salmonella and discussed the different mechanisms of the same availed by the pathogen at the genotypic and phenotypic levels. Further, we have presented a detailed discussion on Salmonella antibiotic persistence (AP), PI, the host and bacterial virulence factors that can influence PI, and how both AP and PI can lead to AMR.

Novel Heptaplex PCR-Based Diagnostics for Enteric Fever Caused by Typhoidal Salmonella Serovars and Its Applicability in Clinical Blood Culture

Enteric fever is caused by typhoidal Salmonella serovars (Typhi, Paratyphi A, Paratyphi B, and Paratyphi C). Owing to the importance of Salmonella serovars in clinics and public hygiene, reliable diagnostics for typhoidal serovars are crucial. This study aimed to develop a novel diagnostic tool for typhoidal Salmonella serovars and evaluate the use of human blood for clinically diagnosing enteric fever. Five genes were selected to produce specific PCR results against typhoidal Salmonella serovars based on the genes of Salmonella Typhi. Heptaplex PCR, including genetic markers of generic Salmonella, Salmonella enterica subsp. enterica, and typhoidal Salmonella serovars, was developed. Typhoidal Salmonella heptaplex PCR using genomic DNAs from 200 Salmonella strains (112 serovars) provided specifically amplified PCR products for each typhoidal Salmonella serovar. These results suggest that heptaplex PCR can sufficiently discriminate between typhoidal and nontyphoidal Salmonella serovars. Heptaplex PCR was applied to Salmonella-spiked blood cultures directly and provided diagnostic results after 12- or 13.5-h blood culture. Additionally, it demonstrated diagnostic performance with colonies recovered from a 6-h blood culture. This study provides a reliable DNA-based tool for diagnosing typhoidal Salmonella serovars that may be useful in clinical microbiology and epidemiology.

Salmonella Bloodstream Infections

Salmonella is a major foodborne pathogen of both animals and humans. This bacterium is responsible for considerable morbidity and mortality world-wide. Different serovars of this genus cause diseases ranging from self-limiting gastroenteritis to a potentially fatal systemic disease known as enteric fever. Gastrointestinal infections with Salmonella are usually self-limiting and rarely require medical intervention. Bloodstream infections, on the other hand, are often fatal even with hospitalization. This review describes the routes and underlying mechanisms of the extraintestinal dissemination of Salmonella and the chronic infections that sometimes result. It includes information on the pathogenicity islands and individual virulence factors involved in systemic dissemination as well as a discussion of the host factors that mediate susceptibility. Also, the major outbreaks of invasive Salmonella disease in the tropics are described.

The stability analysis of a nonlinear mathematical model for typhoid fever disease

Typhoid fever is a contagious disease that is generally caused by bacteria known as Salmonella typhi. This disease spreads through manure contamination of food or water and infects unprotected people. In this work, our focus is to numerically examine the dynamical behavior of a typhoid fever nonlinear mathematical model. To achieve our objective, we utilize a conditionally stable Runge-Kutta scheme of order 4 (RK-4) and an unconditionally stable non-standard finite difference (NSFD) scheme to better understand the dynamical behavior of the continuous model. The primary advantage of using the NSFD scheme to solve differential equations is its capacity to discretize the continuous model while upholding crucial dynamical properties like the solutions convergence to equilibria and its positivity for all finite step sizes. Additionally, the NSFD scheme does not only address the deficiencies of the RK-4 scheme, but also provides results that are consistent with the continuous system's solutions. Our numerical results demonstrate that RK-4 scheme is dynamically reliable only for lower step size and, consequently cannot exactly retain the important features of the original continuous model. The NSFD scheme, on the other hand, is a strong and efficient method that presents an accurate portrayal of the original model. The purpose of developing the NSFD scheme for differential equations is to make sure that it is dynamically consistent, which means to discretize the continuous model while keeping significant dynamical properties including the convergence of equilibria and positivity of solutions for all step sizes. The numerical simulation also indicates that all the dynamical characteristics of the continuous model are conserved by discrete NSFD scheme. The theoretical and numerical results in the current work can be engaged as a useful tool for tracking the occurrence of typhoid fever disease.

Severe Typhoid Fever Complicated by Superior Mesenteric and Splenic Vein Thrombosis

Typhoid fever (Typhoid or enteric fever) is still the most common bacterial bloodstream infection worldwide, caused by Salmonella typhi. The transmission route is indirect through passive vehicles such as contaminated water or food. Main clinical findings are a fever lasting more than three days, abdominal symptoms, leukocytosis, and anemia. Typhoid can cause a wide range of multi-organ complications. We report a particularly severe form of this infection complicated by superior mesenteric vein and splenic vein thrombosis, an extremely uncommon manifestation.

Milan's forgotten epidemic of summer 1629, a few months before the last great plague: An investigation into the possible cause

An epidemic not attributable to plague caused thousands of deaths in Milan in the summer of 1629, a time of war and famine that immediately preceded the even more fatal Great Plague of 1630 that killed an estimated ten of thousands of people. The 5,993 deaths of 1629 recorded in the Liber Mortuorum of Milan (a city with an estimated population of 130,000 inhabitants at the time) were 45.7% more than the average number recorded between 1601 and 1628. Registered deaths peaked in July, and 3,363 of the deaths (56,1%) were attributed to a febrile illness which, in most cases (2,964, 88%), was not associated with a rash or organ involvement. These deaths involved 1,627 males and 1,334 females and occurred at a median age of 40 years (range 0-95). In this paper, we discuss the possible cause of the epidemic, which may have been an outbreak of typhoid fever.

Oral GSH Exerts a Therapeutic Effect on Experimental Salmonella Meningitis by Protecting BBB Integrity and Inhibiting Salmonella-induced Apoptosis

Bacterial meningitis (BM) is the main cause of the central nervous system (CNS) infection and continues to be an important cause of mortality and morbidity. Glutathione (GSH), an endogenous tripeptide antioxidant, has been proved to exert crucial role in reducing superoxide radicals, hydroxyl radicals and peroxynitrites. The purpose of this study is to expand the application scope of GSH via exploring its therapeutic effect on BM caused by Salmonella typhimurium SL1344 and then provide a novel approach for the treatment of BM. The results suggested that intragastric administration of GSH could significantly increase median survival and improve experimental autoimmune encephalomyelitis score of BM model mice. However, exogenous GSH did not affect the adhesion, invasion and cytotoxicity of SL1344 to C6, BV2 and primary microglia. Due to the contradiction between the therapeutic and bactericidal effects of GSH, the effect of GSH on blood-brain barrier (BBB) was investigated to explore its action target for the treatment of meningitis. GSH was found to repair the damage of BBB and then prevent the leakage of SL1344 from the brain to the blood circulation. The repaired BBB could also effectively reduce the entry of macrophages and neutrophils into the brain, and significantly reverse the microglia activation induced by SL1344. More importantly, exogenous GSH was proved to reduce mouse brain cell apoptosis by inhibiting the activation of caspase-8 followed by caspase-3, and reversing the up-regulation of ICAD and PARP-1 caused by SL1344.

Exploring the prevalence of antibiotic resistance patterns and drivers of antibiotics resistance of Salmonella in livestock and poultry-derived foods: a systematic review and meta-analysis in Bangladesh from 2000 to 2022

Background

Antimicrobial resistance (AMR) is a severe public health problem that Bangladeshis are dealing with nowadays. However, we wanted to investigate the pooled prevalence of Salmonella and AMR in Salmonella strains isolated from livestock- and poultry-derived foods between 1 January 2000 and 31 August 2022.

Methods

The metafor and metareg packages in the R programming language were used to conduct all analyses. We used a random-effect or fixed-effect model for pooled prevalence of Salmonella and AMR to Salmonella, depending on the heterogeneity test for each antibiotic. The heterogeneity was examined using stratified analyses, the meta-regression approach and sensitivity analysis.

Results

The combined prevalence of Salmonella in livestock and poultry-derived food in Bangladesh is 37%, according to the 12-research considered (95% CI: 23%-52%). According to subgroup analysis, neomycin had the lowest prevalence of resistance (4%, 95% CI: 1%-13%), whereas tetracycline had the highest prevalence of resistance (81%, 95% CI: 53%-98%). According to univariate meta-analysis and correlation analysis, the prevalence of Salmonella increased with the study period (β = 0.0179; 95% CI: 0.0059-0.0298, P = 0.0034; R² = 46.11%) and without this, none of aforementioned variables was significantly associated with the detected heterogeneity and there was a positive relationship (r = 0.692, P = 0.001) between the Salmonella prevalence and study period.

Conclusions

AMR is rising alarmingly in Bangladesh by livestock-derived food consumption. However, monitoring and evaluating antibiotic sensitivity trends and developing effective antibiotic regimens may improve Salmonella infection inhibition and control in Bangladesh. Policymakers should be concerned about food handling practices. Doctors should be concerned when using prescribing antibiotics.

Typhoid Control in an Era of Antimicrobial Resistance: Challenges and Opportunities

Historically, typhoid control has been achieved with water and sanitation interventions. Today, in an era of rising antimicrobial resistance (AMR), two World Health Organization-prequalified vaccines are available to accelerate control in the shorter term. Meanwhile, water and sanitation interventions could be implemented in the longer term to sustainably prevent typhoid in low- and middle-income countries. This article first approaches typhoid control from a historical perspective, subsequently presents how vaccination could complement water and sanitation activities, and finally discusses the challenges and opportunities for impactful control of typhoid infection. It also addresses data blind spots and knowledge gaps to focus on for typhoid control and to ultimately progress towards elimination. This article presents a synthesis of discussions held in December 2021 during a roundtable session at the "12th International Conference on Typhoid and Other Invasive Salmonelloses".

Human Salmonellosis: A Continuous Global Threat in the Farm-to-Fork Food Safety Continuum

Salmonella is one of the most common zoonotic foodborne pathogens and a worldwide public health threat. Salmonella enterica is the most pathogenic among Salmonella species, comprising over 2500 serovars. It causes typhoid fever and gastroenteritis, and the serovars responsible for the later disease are known as non-typhoidal Salmonella (NTS). Salmonella transmission to humans happens along the farm-to-fork continuum via contaminated animal- and plant-derived foods, including poultry, eggs, fish, pork, beef, vegetables, fruits, nuts, and flour. Several virulence factors have been recognized to play a vital role in attaching, invading, and evading the host defense system. These factors include capsule, adhesion proteins, flagella, plasmids, and type III secretion systems that are encoded on the Salmonella pathogenicity islands. The increased global prevalence of NTS serovars in recent years indicates that the control approaches centered on alleviating the food animals' contamination along the food chain have been unsuccessful. Moreover, the emergence of antibiotic-resistant Salmonella variants suggests a potential food safety crisis. This review summarizes the current state of the knowledge on the nomenclature, microbiological features, virulence factors, and the mechanism of antimicrobial resistance of Salmonella. Furthermore, it provides insights into the pathogenesis and epidemiology of Salmonella infections. The recent outbreaks of salmonellosis reported in different clinical settings and geographical regions, including Africa, the Middle East and North Africa, Latin America, Europe, and the USA in the farm-to-fork continuum, are also highlighted.

The Prevalence of Undiagnosed Salmonella enterica Serovar Typhi in Healthy School-Aged Children in Osun State, Nigeria

Typhoid fever remains a significant public health concern due to cases of mis-/overdiagnosis. Asymptomatic carriers play a role in the transmission and persistence of typhoid fever, especially among children, where limited data exist in Nigeria and other endemic countries. We aim to elucidate the burden of typhoid fever among healthy school-aged children using the best surveillance tool(s). In a semi-urban/urban state (Osun), 120 healthy school-aged children under 15 years were enrolled. Whole blood and fecal samples were obtained from consenting children. ELISA targeting the antigen lipopolysaccharide (LPS) and anti-LPS antibodies of Salmonella Typhi, culture, polymerase chain reaction (PCR), and next-generation sequencing (NGS) were used to analyze the samples. At least one of the immunological markers was detected in 65.8% of children, with 40.8%, 37.5%, and 39% of children testing positive for IgM, IgG, and antigen, respectively. Culture, PCR, and NGS assays did not detect the presence of Salmonella Typhi in the isolates. This study demonstrates a high seroprevalence of Salmonella Typhi in these healthy children but no carriage, indicating the inability to sustain transmission. We also demonstrate that using a single technique is insufficient for typhoid fever surveillance in healthy children living in endemic areas.

Phenotypic and genotypic survey of antibiotic resistance in Salmonella enterica isolates from dairy farms in Uruguay

Salmonella enterica is an important zoonotic pathogen that is frequently identified in dairy farming systems. An increase in antibiotic resistance has led to inadequate results of treatments, with impacts on animal and human health. Here, the phenotypic and genotypic susceptibility patterns of Salmonella isolates from dairy cattle and dairy farm environments were evaluated and compared. A collection of 75 S. enterica isolates were evaluated, and their phenotypic susceptibility was determined. For genotypic characterization, the whole genomes of the isolates were sequenced, and geno-serotypes, sequence types (STs) and core-genome-sequence types were determined using the EnteroBase pipeline. To characterize antibiotic resistance genes and gene mutations, tools from the Center for Genomic Epidemiology were used. Salmonella Dublin (SDu), S. Typhimurium (STy), S. Anatum (SAn), S. Newport (SNe), S. Agona (Sag), S. Montevideo (SMo) and IIIb 61:i:z53 were included in the collection. A single sequence type was detected per serovar. Phenotypic non-susceptibility to streptomycin and tetracycline was very frequent in the collection, and high non-susceptibility to ciprofloxacin was also observed. Multidrug resistance (MDR) was observed in 42 isolates (56.0%), with SAn and STy presenting higher MDR than the other serovars, showing non-susceptibility to up to 6 groups of antibiotics. Genomic analysis revealed the presence of 21 genes associated with antimicrobial resistance (AMR) in Salmonella isolates. More than 60% of the isolates carried some gene associated with resistance to aminoglycosides and tetracyclines. Only one gene associated with beta-lactam resistance was found, in seven isolates. Two different mutations were identified, parC_T57S and acrB_R717Q, which confer resistance to quinolones and azithromycin, respectively. The accuracy of predicting antimicrobial resistance phenotypes based on AMR genotypes was 83.7%. The genomic approach does not replace the phenotypic assay but offers valuable information for the survey of circulating antimicrobial resistance. This work represents one of the first studies evaluating phenotypic and genotypic AMR in Salmonella from dairy cattle in South America.

Genomic landscape of the emerging XDR Salmonella Typhi for mining druggable targets clpP, hisH, folP and gpmI and screening of novel TCM inhibitors, molecular docking and simulation analyses

Typhoid fever is transmitted by ingestion of polluted water, contaminated food, and stool of typhoid-infected individuals, mostly in developing countries with poor hygienic environments. To find novel therapeutic targets and inhibitors, We employed a subtractive genomics strategy towards Salmonella Typhi and the complete genomes of eight strains were primarily subjected to the EDGAR tool to predict the core genome (n = 3207). Human non-homology (n = 2450) was followed by essential genes identification (n = 37). The STRING database predicted maximum protein-protein interactions, followed by cellular localization. The virulent/immunogenic ability of predicted genes were checked to differentiate drug and vaccine targets. Furthermore, the 3D models of the identified putative proteins encoded by the respective genes were constructed and subjected to druggability analyses where only "highly druggable" proteins were selected for molecular docking and simulation analyses. The putative targets ATP-dependent CLP protease proteolytic subunit, Imidazole glycerol phosphate synthase hisH, 7,8-dihydropteroate synthase folP and 2,3-bisphosphoglycerate-independent phosphoglycerate mutase gpmI were screened against a drug-like library (n = 12,000) and top hits were selected based on H-bonds, RMSD and energy scores. Finally, the ADMET properties for novel inhibitors ZINC19340748, ZINC09319798, ZINC00494142, ZINC32918650 were optimized followed by binding free energy (MM/PBSA) calculation for ligand-receptor complexes. The findings of this work are expected to aid in expediting the identification of novel protein targets and inhibitors in combating typhoid Salmonellosis, in addition to the already existing therapies.

Immune evasion and persistence in enteric bacterial pathogens

The major function of the mammalian immune system is to prevent and control infections caused by enteropathogens that collectively have altered human destiny. In fact, as the gastrointestinal tissues are the major interface of mammals with the environment, up to 70% of the human immune system is dedicated to patrolling them The defenses are multi-tiered and include the endogenous microflora that mediate colonization resistance as well as physical barriers intended to compartmentalize infections. The gastrointestinal tract and associated lymphoid tissue are also protected by sophisticated interleaved arrays of active innate and adaptive immune defenses. Remarkably, some bacterial enteropathogens have acquired an arsenal of virulence factors with which they neutralize all these formidable barriers to infection, causing disease ranging from mild self-limiting gastroenteritis to in some cases devastating human disease.

ANTIBIOTIC RESISTANCE OF SALMONELLA TYPHI CARRIER ASSOCIATED WITH GALL BLADDER CHRONIC INFECTION IN AL-NAJAF PROVINCE

OBJECTIVE

The aim: This study was undertaken to identify antibiotic resistance of Salmonella Typhi in specimens of gall bladder tissue after cholecystectomy.

PATIENTS AND METHODS

Materials and methods: Salmonella Typhi identification from the isolates have been depended on morphology of the colony and biochemical tests as a first step in identification while final identification has been achieved by the automated VITEK-2 compact system then PCR technique.

RESULTS

Results: Depending to finding via the VITEK tests and PCR technique and thirty-five Salmonella Typhi sample have been obtained. This research shown that about 35 (70%) positive result contains, 12 (34.3%) isolates was positive from stool and 23(65.7%) from gall bladder tissue. The results revealed difference in S. Typhi resistance to some antibiotics, where S. Typhi has wide-ranging sensitivity: 35 (100%) to Cefepime, Cefixime and Ciprofloxacin and revealed great sensitivity 22 (62.8%) to Ampicillin. S. Typhi isolates proved extremely resistant 19 (54.2%) and 25 (71.4%) to Trimethoprim/Sulphamethoxazole and Chloramphenicol respectively. Increment in the rate of Salmonella that has multidrug resistance to chloramphenicol, ampicillin, furazolidonecotrimoxazole, streptomycin, and tetracycline is a developing problem and worldwide worry matte.

CONCLUSION

Conclusions: Resistant forms of Salmonella enteric serotype Typhi were detected with increment in the rate of multidrug resistance to chloramphenicol, ampicillin, and tetracycline so currently, Cefepime, Cefixime and Ciprofloxacin and revealed great sensitivity and have become the mainstay of treatment. Challenging difficult which rises in this study is the extend of Multidrug resistant strain (MDR) of S. Typhi.

Treatment of enteric fever (typhoid and paratyphoid fever) with cephalosporins

BACKGROUND

Typhoid and paratyphoid (enteric fever) are febrile bacterial illnesses common in many low- and middle-income countries. The World Health Organization (WHO) currently recommends treatment with azithromycin, ciprofloxacin, or ceftriaxone due to widespread resistance to older, first-line antimicrobials. Resistance patterns vary in different locations and are changing over time. Fluoroquinolone resistance in South Asia often precludes the use of ciprofloxacin. Extensively drug-resistant strains of enteric fever have emerged in Pakistan. In some areas of the world, susceptibility to old first-line antimicrobials, such as chloramphenicol, has re-appeared. A Cochrane Review of the use of fluoroquinolones and azithromycin in the treatment of enteric fever has previously been undertaken, but the use of cephalosporins has not been systematically investigated and the optimal choice of drug and duration of treatment are uncertain.

OBJECTIVES

To evaluate the effectiveness of cephalosporins for treating enteric fever in children and adults compared to other antimicrobials.

SEARCH METHODS

We searched the Cochrane Infectious Diseases Group Specialized Register, CENTRAL, MEDLINE, Embase, LILACS, the WHO ICTRP and ClinicalTrials.gov up to 24 November 2021. We also searched reference lists of included trials, contacted researchers working in the field, and contacted relevant organizations.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) in adults and children with enteric fever that compared a cephalosporin to another antimicrobial, a different cephalosporin, or a different treatment duration of the intervention cephalosporin. Enteric fever was diagnosed on the basis of blood culture, bone marrow culture, or molecular tests.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were clinical failure, microbiological failure and relapse. Our secondary outcomes were time to defervescence, duration of hospital admission, convalescent faecal carriage, and adverse effects. We used the GRADE approach to assess certainty of evidence for each outcome.

MAIN RESULTS

We included 27 RCTs with 2231 total participants published between 1986 and 2016 across Africa, Asia, Europe, the Middle East and the Caribbean, with comparisons between cephalosporins and other antimicrobials used for the treatment of enteric fever in children and adults. The main comparisons are between antimicrobials in most common clinical use, namely cephalosporins compared to a fluoroquinolone and cephalosporins compared to azithromycin. Cephalosporin (cefixime) versus fluoroquinolones Clinical failure, microbiological failure and relapse may be increased in patients treated with cefixime compared to fluoroquinolones in three small trials published over 14 years ago: clinical failure (risk ratio (RR) 13.39, 95% confidence interval (CI) 3.24 to 55.39; 2 trials, 240 participants; low-certainty evidence); microbiological failure (RR 4.07, 95% CI 0.46 to 36.41; 2 trials, 240 participants; low-certainty evidence); relapse (RR 4.45, 95% CI 1.11 to 17.84; 2 trials, 220 participants; low-certainty evidence). Time to defervescence in participants treated with cefixime may be longer compared to participants treated with fluoroquinolones (mean difference (MD) 1.74 days, 95% CI 0.50 to 2.98, 3 trials, 425 participants; low-certainty evidence). Cephalosporin (ceftriaxone) versus azithromycin Ceftriaxone may result in a decrease in clinical failure compared to azithromycin, and it is unclear whether ceftriaxone has an effect on microbiological failure compared to azithromycin in two small trials published over 18 years ago and in one more recent trial, all conducted in participants under 18 years of age: clinical failure (RR 0.42, 95% CI 0.11 to 1.57; 3 trials, 196 participants; low-certainty evidence); microbiological failure (RR 1.95, 95% CI 0.36 to 10.64, 3 trials, 196 participants; very low-certainty evidence). It is unclear whether ceftriaxone increases or decreases relapse compared to azithromycin (RR 10.05, 95% CI 1.93 to 52.38; 3 trials, 185 participants; very low-certainty evidence). Time to defervescence in participants treated with ceftriaxone may be shorter compared to participants treated with azithromycin (mean difference of -0.52 days, 95% CI -0.91 to -0.12; 3 trials, 196 participants; low-certainty evidence). Cephalosporin (ceftriaxone) versus fluoroquinolones It is unclear whether ceftriaxone has an effect on clinical failure, microbiological failure, relapse, and time to defervescence compared to fluoroquinolones in three trials published over 28 years ago and two more recent trials: clinical failure (RR 3.77, 95% CI 0.72 to 19.81; 4 trials, 359 participants; very low-certainty evidence); microbiological failure (RR 1.65, 95% CI 0.40 to 6.83; 3 trials, 316 participants; very low-certainty evidence); relapse (RR 0.95, 95% CI 0.31 to 2.92; 3 trials, 297 participants; very low-certainty evidence) and time to defervescence (MD 2.73 days, 95% CI -0.37 to 5.84; 3 trials, 285 participants; very low-certainty evidence). It is unclear whether ceftriaxone decreases convalescent faecal carriage compared to the fluoroquinolone gatifloxacin (RR 0.18, 95% CI 0.01 to 3.72; 1 trial, 73 participants; very low-certainty evidence) and length of hospital stay may be longer in participants treated with ceftriaxone compared to participants treated with the fluoroquinolone ofloxacin (mean of 12 days (range 7 to 23 days) in the ceftriaxone group compared to a mean of 9 days (range 6 to 13 days) in the ofloxacin group; 1 trial, 47 participants; low-certainty evidence).

AUTHORS' CONCLUSIONS

Based on very low- to low-certainty evidence, ceftriaxone is an effective treatment for adults and children with enteric fever, with few adverse effects. Trials suggest that there may be no difference in the performance of ceftriaxone compared with azithromycin, fluoroquinolones, or chloramphenicol. Cefixime can also be used for treatment of enteric fever but may not perform as well as fluoroquinolones.  We are unable to draw firm general conclusions on comparative contemporary effectiveness given that most trials were small and conducted over 20 years previously. Clinicians need to take into account current, local resistance patterns in addition to route of administration when choosing an antimicrobial.

Spatiotemporal and Seasonal Trends of Class A and B Notifiable Infectious Diseases in China: A Retrospective Analysis (Preprint)

BACKGROUND

China is the most populous country globally and has made significant achievements in the control of infectious diseases over the last decades. The 2003 SARS epidemic triggered the initiation of the China Information System for Disease Control and Prevention (CISDCP). Since then, numerous studies have investigated the epidemiological features and trends of individual infectious diseases in China; however, few considered the changing spatiotemporal trends and seasonality of these infectious diseases over time.

OBJECTIVE

This study aims to systematically review the spatiotemporal trends and seasonal characteristics of class A and class B notifiable infectious diseases in China during 2005-2020.

METHODS

We extracted the incidence and mortality data of 8 types (27 diseases) of notifiable infectious diseases from the CISDCP. We used the Mann-Kendall and Sen's methods to investigate the diseases' temporal trends, Moran I statistic for their geographical distribution, and circular distribution analysis for their seasonality.

RESULTS

Between January 2005 and December 2020, 51,028,733 incident cases and 261,851 attributable deaths were recorded. Pertussis (P=.03), dengue fever (P=.01), brucellosis (P=.001), scarlet fever (P=.02), AIDS (P<.001), syphilis (P<.001), hepatitis C (P<.001) and hepatitis E (P=.04) exhibited significant upward trends. Furthermore, measles (P<.001), bacillary and amebic dysentery (P<.001), malaria (P=.04), dengue fever (P=.006), brucellosis (P=.03), and tuberculosis (P=.003) exhibited significant seasonal patterns. We observed marked disease burden-related geographic disparities and heterogeneities. Notably, high-risk areas for various infectious diseases have remained relatively unchanged since 2005. In particular, hemorrhagic fever and brucellosis were largely concentrated in Northeast China; neonatal tetanus, typhoid and paratyphoid, Japanese encephalitis, leptospirosis, and AIDS in Southwest China; BAD in North China; schistosomiasis in Central China; anthrax, tuberculosis, and hepatitis A in Northwest China; rabies in South China; and gonorrhea in East China. However, the geographical distribution of syphilis, scarlet fever, and hepatitis E drifted from coastal to inland provinces during 2005-2020.

CONCLUSIONS

The overall infectious disease burden in China is declining; however, hepatitis C and E, bacterial infections, and sexually transmitted infections continue to multiply, many of which have spread from coastal to inland provinces.

Clinical Characteristics and Antibiotics Sensitivity of Culture Positive Typhoid Fever Patients in Baghdad Teaching Hospital - A Single Center Study

BACKGROUND: Enteric fever caused by Salmonella Typhi is an endemic disease in Iraq. Variations in presentations make it a diagnostic challenge. If untreated or treated inappropriately then it is a serious disease with potentially life-threatening complications. The recent emergence of drug resistant strains of S. Typhi is a rising public health problem and a clinical concern to the physician. AIM: The objectives of the study were to assess and describe the patterns of antimicrobial resistance, clinical characteristics, epidemiological distribution, and complications of typhoid fever. PATIENTS AND METHODS: Fifty cases of typhoid fever (culture proven) were collected during the period from February 2019 to November 2019 in the medical wards of Baghdad Teaching Hospital. Detailed history, physical examination, and laboratory investigations were conducted and statistical analysis of the results was done, prospective observational study was conducted. RESULTS: During the study period, 50 cases of typhoid fever were documented, mean age of presentation was 30.7 ± 12.8, 60% of the cases were male gender, gastrointestinal complications were the most common (90%) followed by hematological complications (71%). Mortality of typhoid fever in our study was 2%. High percentage of resistance to third generation cephalosporins, ciprofloxacin, and azithromycin was found (96%, 56%, and 56%, respectively) while good sensitivity to trimethoprim and meropenem was found (94% and 76%, respectively). Significant association was also found between the development of typhoid fever complications and the presence of anemia, thrombocytopenia, lymphopenia, and eosinopenia. Significant association was also found between the complications and the infection with strains resistant to cephalosporins, ciprofloxacin, and azithromycin. CONCLUSIONS: There is a concerning increase in resistance toward cephalosporins, ciprofloxacin, and azithromycin while meropenem and trimethoprim are emerging as effective drugs. There was high incidence of complications found (84%).Lymphopenia, anemia, eosinopenia, and thrombocytopenia are independent risk factors for the development of complications of typhoid fever.

Paratyphoid Fever A: Infection and Prevention

Enteric fever is caused by Salmonella enterica serovar Typhi, Salmonella enterica serovar Paratyphi A, B, and C. While S. Typhi remains the primary causative agent of enteric fever, S. Paratyphi A is responsible for an increasing portion of enteric fever incidence. However, the current available vaccines for enteric fever are all developed from S. Typhi, and lack adequate cross immune protection against paratyphoid fever A. Therefore, paratyphoid A vaccines are urgently needed. The present paper reviews the latest progresses in pathogenesis, global burden, infection features of paratyphoid fever A, as well as the status of vaccine development, highlighting the necessity for the development of vaccines against paratyphoid fever A.

Inflammatory Monocytes Promote Granuloma-Mediated Control of Persistent Salmonella Infection

Persistent infections generally involve a complex balance between protective immunity and immunopathology. We used a murine model to investigate the role of inflammatory monocytes in immunity and host defense against persistent salmonellosis. Mice exhibit increased susceptibility to persistent infection when inflammatory monocytes cannot be recruited into tissues or when they are depleted at specific stages of persistent infection. Inflammatory monocytes contribute to the pathology of persistent salmonellosis and cluster with other cells in pathogen-containing granulomas. Depletion of inflammatory monocytes during the chronic phase of persistent salmonellosis causes regression of already established granulomas with resultant pathogen growth and spread in tissues. Thus, inflammatory monocytes promote granuloma-mediated control of persistent salmonellosis and may be key to uncovering new therapies for granulomatous diseases.

Typhoid fever presenting with gastric ulcer bleeding

Background

Enteric fever is a systemic disease caused by Salmonella enterica serovar Typhi or Salmonella enterica serovar Paratyphi, characterized by high fever and abdominal pain. Most patients with enteric fever improve within a few days after antibiotic treatment. However, some patients do not recover as easily and develop fatal life-threatening complications, including intestinal hemorrhage. Lower gastrointestinal bleeding has been reported in 10% of cases. However, upper gastrointestinal bleeding has rarely been reported in patients with enteric fever. We present a case of gastric ulcer hemorrhage caused by enteric fever.

Case presentation

A 32-year-old woman, complaining of fever lasting four days and right upper quadrant pain and melena that started one day before admission, consulted our hospital. Abdominal computed tomography revealed mild hepatomegaly and gastroscopy revealed multiple active gastric ulcers with flat black hemorrhagic spots. The melena of the patient stopped on the third day. On the fifth admission day, she developed hematochezia. At that time, Salmonella enterica serovar Typhi was isolated from the blood culture. The antibiotic regimen was switched to ceftriaxone. Her hematochezia spontaneously resolved the following day. Finally, the patient was discharged on the 12th admission day without clinical symptoms. However, her fever recurred one month after discharge, and she was readmitted and Salmonella enterica serovar Typhi was confirmed again via blood culture. She was treated with ceftriaxone for one month, and was discharged without complications.

Conclusion

Our case showed that although rare, active gastric ulcers can develop in patients with enteric fever. Therefore, upper and lower gastrointestinal bleeding should be suspected in patients with enteric fever, especially showing relapsing bacteremia.

Nano-Antibacterials Using Medicinal Plant Components: An Overview

Gradual emergence of new bacterial strains, resistant to one or more antibiotics, necessitates development of new antibacterials to prevent us from newly evolved disease-causing, drug-resistant, pathogenic bacteria. Different inorganic and organic compounds have been synthesized as antibacterials, but with the problem of toxicity. Other alternatives of using green products, i.e., the medicinal plant extracts with biocompatible and potent antibacterial characteristics, also had limitation because of their low aqueous solubility and therefore less bioavailability. Use of nanotechnological strategy appears to be a savior, where phytochemicals are nanonized through encapsulation or entrapment within inorganic or organic hydrophilic capping agents. Nanonization of such products not only makes them water soluble but also helps to attain high surface to volume ratio and therefore high reaction area of the nanonized products with better therapeutic potential, over that of the equivalent amount of raw bulk products. Medicinal plant extracts, whose prime components are flavonoids, alkaloids, terpenoids, polyphenolic compounds, and essential oils, are in one hand nanonized (capped and stabilized) by polymers, lipids, or clay materials for developing nanodrugs; on the other hand, high antioxidant activity of those plant extracts is also used to reduce various metal salts to produce metallic nanoparticles. In this review, five medicinal plants, viz., tulsi (Ocimum sanctum), turmeric (Curcuma longa), aloe vera (Aloe vera), oregano (Oregano vulgare), and eucalyptus (Eucalyptus globulus), with promising antibacterial potential and the nanoformulations associated with the plants' crude extracts and their respective major components (eugenol, curcumin, anthraquinone, carvacrol, eucalyptus oil) have been discussed with respect to their antibacterial potency.

Simultaneous Efficient Decontamination of Bacteria and Heavy Metals via Capacitive Deionization Using Polydopamine/Polyhexamethylene Guanidine Co-deposited Activated Carbon Electrodes

The contamination of pathogenic micro-organisms and heavy metals in drinking water sources poses a serious threat to human health, which raises the demand for efficient water treatments. Herein, multi-functional capacitive deionization (CDI) electrodes were developed for the simultaneous decontamination of bacteria and heavy metal contaminants. Polyhexamethylene guanidine (PHMG), an antibacterial polymer, was deposited on the surface of the activated carbon (AC) electrode with the assistance of mussel-inspired polydopamine (PDA) chemistry. The main characterization results proved successful co-deposition of PDA and PHMG on the AC electrode, forming a hydrophilic coating layer in one step. Electrochemical analyses indicated that the AC-PDA/PHMG electrodes presented satisfactory capacitive behaviors, with outstanding salt adsorption capacity and cycling stability. The modified electrodes also exhibit excellent disinfection performance and heavy metal adsorption performance. The bacterial elimination rate of co-deposited electrodes grew along with the increase in the PHMG content. Particularly, AC-PDA/PHMG₂ electrodes successfully removed and deactivated 99.11% Escherichia coli and 98.67% Pseudomonas aeruginosa (10⁴ CFU mL^-1) in water within 60 min. Furthermore, three flow cells made by AC-PDA/PHMG₂ electrodes connected in series achieved efficient removal of salt, heavy metals such as lead and cadmium, and bacteria simultaneously, which indicated that the adsorption performance is significantly improved compared with pristine AC electrodes. These results denote the enormous potential of this one-step prepared multi-functional electrodes for facile and effective water purification using CDI technology.

Antimicrobial Resistance in Salmonella Typhi Isolated From a Referral Hospital of Kathmandu, Nepal

Purpose:

The morbidity and mortality due to typhoid fever can be significantly reduced with the use of effective antibiotics. At present, fluoroquinolones, third generation cephalosporins, and azithromycin are widely used to treat typhoid fever. However, changing antibiotic susceptibility among Salmonella Typhi and Salmonella Paratyphi poses a particular challenge to the therapeutic management of enteric fever. The objective of this study was to assess the antibiotic susceptibility pattern of Salmonella Typhi isolates.

Patients and Methods:

A total of 706 blood specimens were collected from febrile patients attending the outpatient department of Kathmandu Model Hospital during June to September, 2018. The antibiotic susceptibility testing for 11 different antibiotics (nalidixic acid, ciprofloxacin, ofloxacin, levofloxacin, cefixime, ceftriaxone, cefotaxime, azithromycin, cotrimoxazole, chloramphenicol, and amoxicillin) was performed by disk diffusion method. Furthermore, minimum inhibitory concentration (MIC) values of ciprofloxacin, ofloxacin, and azithromycin were determined by agar dilution method. Mutation at gyrA ser83 associated with reduced susceptibility to fluoroquinolones was determined by PCR-RFLP.

Results:

Out of 706 blood samples, 6.94% (n = 49) were culture positive for Salmonella enterica (S. Typhi, n = 46). It was revealed that 97.8% S. Typhi isolates were susceptible to conventional first-line antibiotics (ampicillin, chloramphenicol, and cotrimoxazole), 97.3% to cephalosporins and 95.7% to azithromycin. S. Typhi were either resistant or intermediately susceptible to fluoroquinolones: 97.8% to ciprofloxacin, 91.3% to ofloxacin, and 89.1% to levofloxacin. The MIC of ciprofloxacin, ofloxacin, and azithromycin for S. Typhi ranged from 0.008 to 32, 0.03 to 16, and 2 to 8 μg/mL, respectively. Out of 46 S. Typhi isolates, 44 (95.65%) had gyrA ser83 mutation.

Conclusion:

Fluoroquinolones have poor activity against Salmonella Typhi. The trends of increasing azithromycin MIC value among S. Typhi might limit its use for the treatment of typhoid fever. Effectiveness of conventional first-line antibiotics in vitro suggests considering their clinical use after large-scale studies.

Prevalence and awareness of mode of transmission of typhoid fever in patients diagnosed with Salmonella typhi and paratyphi infections at the Saint Elisabeth General Hospital Shisong, Bui Division, Cameroon

Introduction

typhoid fever is a systemic infectious disease caused by the bacteria Salmonella enterica subspecies (typhi). It is a major cause of morbidity and mortality worldwide. This cross-sectional descriptive study aimed at determining the prevalence and awareness of the mode of transmission of Salmonella typhi among patients at the Saint Elisabeth General Hospital Shisong of Cameroon.

Methods

the study carried out from March 1^st, 2017 to May 31^st, 2017 recruited patients who presented at the hospital with clinical signs and symptoms of typhoid fever and who had lab requests for stool culture requested by the resident physician. The prevalence of Salmonella typhi infections among the patients and the proportion of patients with adequate knowledge on the mode of transmission of Salmonella typhi were estimated at a 95% CI. Data were analyzed using Epi info7.1.3.3.

Results

out of the 172 patients recruited for the studies, 52 (30.1%) were diagnosed with Salmonella typhi, 59.6% of which were male. Also, 3 (5.8%) were diagnosed with Salmonella paratyphoid A. A positive correlation between knowledge on the mode of transmission of Salmonella typhi and the level of education was established, showing that 92% of participants with a higher level of education indicating that typhoid fever can be contracted through consumption of contaminated water.

Conclusion

high prevalence of typhoid fever was observed in our study. The unawareness of the patients on typhoid fever and its contraction through contaminated water and food was positively correlated to the level of educations of the patients. These findings, therefore, suggest a public health challenge faced by inhabitants in this region where typhoid fever remains endemic. Scarcity of potable water, improper drainage systems, and problems of unsanitary toilets in Cameroon require urgent intervention.

Structural optimization of natural product fusaric acid to discover novel T3SS inhibitors of Salmonella

Type III secretion system (T3SS) plays a critical role in host cell invasion and pathogenesis of Salmonella. We recently identified the mycotoxin fusaric acid (FA) as a T3SS inhibitor of Salmonella. Herein, twenty-two diphenylsulfane derivatives were designed and synthesized using FA as a lead compound through scaffold hopping. Among them, SL-8 and SL-19 possessing strong anti-T3SS and anti-invasion activity were identified as T3SS inhibitors with improvement in potency as compared to FA. The inhibitory mechanisms on SPI-1 did not depend on the HilD-HilC-RtsA-HilA or PhoP-PhoQ pathway or the assembly of T3SS needle complex. Accordingly, we proposed that the inhibitory effects of SL-8 and SL-19 on SPI-1 probably influence the formation of SicA/InvF-effector complex or other related proteins.

Comparison of Strategies for Typhoid Conjugate Vaccine Introduction in India: A Cost-Effectiveness Modeling Study

Background

Typhoid fever causes substantial global mortality, with almost half occurring in India. New typhoid vaccines are highly effective and recommended by the World Health Organization for high-burden settings. There is a need to determine whether and which typhoid vaccine strategies should be implemented in India.

Methods

We assessed typhoid vaccination using a dynamic compartmental model, parameterized by and calibrated to disease and costing data from a recent multisite surveillance study in India. We modeled routine and 1-time campaign strategies that target different ages and settings. The primary outcome was cost-effectiveness, measured by incremental cost-effectiveness ratios (ICERs) benchmarked against India’s gross national income per capita (US$2130).

Results

Both routine and campaign vaccination strategies were cost-saving compared to the status quo, due to averted costs of illness. The preferred strategy was a nationwide community-based catchup campaign targeting children aged 1–15 years alongside routine vaccination, with an ICER of $929 per disability-adjusted life-year averted. Over the first 10 years of implementation, vaccination could avert 21–39 million cases and save $1.6–$2.2 billion. These findings were broadly consistent across willingness-to-pay thresholds, epidemiologic settings, and model input distributions.

Conclusions

Despite high initial costs, routine and campaign typhoid vaccination in India could substantially reduce mortality and was highly cost-effective.

Geographic Pattern of Typhoid Fever in India: A Model-Based Estimate of Cohort and Surveillance Data

Background

Typhoid fever remains a major public health problem in India. Recently, the Surveillance for Enteric Fever in India program completed a multisite surveillance study. However, data on subnational variation in typhoid fever are needed to guide the introduction of the new typhoid conjugate vaccine in India.

Methods

We applied a geospatial statistical model to estimate typhoid fever incidence across India, using data from 4 cohort studies and 6 hybrid surveillance sites from October 2017 to March 2020. We collected geocoded data from the Demographic and Health Survey in India as predictors of typhoid fever incidence. We used a log linear regression model to predict a primary outcome of typhoid incidence.

Results

We estimated a national incidence of typhoid fever in India of 360 cases (95% confidence interval [CI], 297–494) per 100 000 person-years, with an annual estimate of 4.5 million cases (95% CI, 3.7–6.1 million) and 8930 deaths (95% CI, 7360–12 260), assuming a 0.2% case-fatality rate. We found substantial geographic variation of typhoid incidence across the country, with higher incidence in southwestern states and urban centers in the north.

Conclusions

There is a large burden of typhoid fever in India with substantial heterogeneity across the country, with higher burden in urban centers.

Samonella typhi infection-related appendicitis: A case report

BACKGROUND

Acute appendicitis is one of the most common acute abdominal emergencies around the world, which is always associated with infection. Infection with Salmonella typhi, an enteric pathogen, is a rare cause of acute appendicitis. We here report a patient with acute appendicitis associated with Samonella typhi infection, accompanied with spleen and kidney infarction, providing a rare example for a common surgical emergency.

CASE SUMMARY

A 25-year-old Pakistani man presented to the hospital with a 3-d history of fevers, vomiting, and abdominal pain. Computed tomography (CT) revealed a thickened intestinal wall of the ileocecal junction with multiple enlarged lymph nodes nearby. He was diagnosed with acute appendicitis and received laparoscopic appendectomy, which showed mild inflammation of the appendix. After the surgery, the patient presented again with a high fever (> 39 °C) and diarrhea. A CT angiography scan indicated spleen and kidney infarction. According to the blood culture, the diagnosis was finally clear to be Samonella typhi infection. The pyrexia and enteric symptoms were relieved after the application of intravenous levofloxacin.

CONCLUSION

This case, characterized by the combination of Salmonella typhi infection, acute appendicitis, and renal and splenic infraction, serves as a rare example for a common surgical emergency.

The Abundance and Organization of Salmonella Extracellular Polymeric Substances in Gallbladder-Mimicking Environments and In Vivo

Salmonella enterica serovar Typhi (S. Typhi) causes chronic infections by establishing biofilms on cholesterol gallstones. Production of extracellular polymeric substances (EPSs) is key to biofilm development and biofilm architecture depends on which EPSs are made. The presence and spatial distribution of Salmonella EPSs produced in vitro and in vivo were investigated in S. Typhimurium and S. Typhi biofilms by confocal microscopy. Comparisons between serovars and EPS-mutant bacteria were examined by growth on cholesterol-coated surfaces, with human gallstones in ox or human bile, and in mice with gallstones. On cholesterol-coated surfaces, major differences in EPS biomass were not found between serovars. Co-culture biofilms containing wild-type (WT) and EPS-mutant bacteria demonstrated WT compensation for EPS mutations. Biofilm EPS analysis from gallbladder-mimicking conditions found that culture in human bile more consistently replicated the relative abundance and spatial organization of each EPS on gallstones from the chronic mouse model than culture in ox bile. S. Typhimurium biofilms cultured in vitro on gallstones in ox bile exhibited co-localized pairings of curli fimbriae/lipopolysaccharide and O antigen capsule/cellulose while these associations were not present in S. Typhi biofilms or in mouse gallstone biofilms. In general, inclusion of human bile with gallstones in vitro replicated biofilm development on gallstones in vivo, demonstrating its strength as a model for studying biofilm parameters or EPS-directed therapeutic treatments.

S. Typhi derived vaccines and a proposal for outer membrane vesicles (OMVs) as potential vaccine for typhoid fever

Typhoid fever is a serious systemic infection caused by Salmonella Typhi (S. Typhi), spread by the feco-oral route and closely associated with poor food hygiene and inadequate sanitation. Nearly 93% of S. Typhi strains have acquired antibiotic resistance against most antibiotics. Vaccination is the only promising way to prevent typhoid fever. This review covers the nature and composition of S. Typhi, pathogenecity and mode of infection, epidemiology, and nature of drug resistance. Several components (Vi-polysaccharides, O-antigens, flagellar antigens, full length OMPs, and short peptides from OMPs) of S. Typhi have been utilized for vaccine design for protection against typhoid fever. Vaccine delivery systems also contribute to efficacy of the vaccines. In this study, we propose to develop S. Typhi derived OMVs as vaccine for protection against typhoid fevers.

A global resource for genomic predictions of antimicrobial resistance and surveillance of Salmonella Typhi at pathogenwatch

As whole-genome sequencing capacity becomes increasingly decentralized, there is a growing opportunity for collaboration and the sharing of surveillance data within and between countries to inform typhoid control policies. This vision requires free, community-driven tools that facilitate access to genomic data for public health on a global scale. Here we present the Pathogenwatch scheme for Salmonella enterica serovar Typhi (S. Typhi), a web application enabling the rapid identification of genomic markers of antimicrobial resistance (AMR) and contextualization with public genomic data. We show that the clustering of S. Typhi genomes in Pathogenwatch is comparable to established bioinformatics methods, and that genomic predictions of AMR are highly concordant with phenotypic susceptibility data. We demonstrate the public health utility of Pathogenwatch with examples selected from >4,300 public genomes available in the application. Pathogenwatch provides an intuitive entry point to monitor of the emergence and spread of S. Typhi high risk clones.

Whole genome sequencing data are increasingly becoming routinely available but generating actionable insights is challenging. Here, the authors describe Pathogenwatch, a web tool for genomic surveillance of S. Typhi, and demonstrate its use for antimicrobial resistance assignment and strain risk assessment.

Mass burial genomics reveals outbreak of enteric paratyphoid fever in the Late Medieval trade city Lübeck

Medieval Europe was repeatedly affected by outbreaks of infectious diseases, some of which reached epidemic proportions. A Late Medieval mass burial next to the Heiligen-Geist-Hospital in Lübeck (present-day Germany) contained the skeletal remains of more than 800 individuals who had presumably died from infectious disease. From 92 individuals, we screened the ancient DNA extracts for the presence of pathogens to determine the cause of death. Metagenomic analysis revealed evidence of Salmonella enterica subsp. enterica serovar Paratyphi C, suggesting an outbreak of enteric paratyphoid fever. Three reconstructed S. Paratyphi C genomes showed close similarity to a strain from Norway (1200 CE). Radiocarbon dates placed the disease outbreak in Lübeck between 1270 and 1400 cal CE, with historical records indicating 1367 CE as the most probable year. The deceased were of northern and eastern European descent, confirming Lübeck as an important trading center of the Hanseatic League in the Baltic region.

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Salmonella enterica Paratyphi C detected in remains from a mass burial in Lübeck

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Outbreak of enteric paratyphoid fever likely occurred in 1367 CE

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Pathogen genomes showed close similarity to a strain from Norway (1200 CE)

Broadly reactive human CD4+ T cells against Enterobacteriaceae are found in the naïve repertoire and are clonally expanded in the memory repertoire

Enterobacteriaceae are a large family of Gram-negative bacteria that includes both commensals and opportunistic pathogens. The latter can cause severe nosocomial infections, with outbreaks of multi-antibiotics resistant strains, thus being a major public health threat. In this study, we report that Enterobacteriaceae-reactive memory Th cells were highly enriched in a CCR6+ CXCR3+ Th1*/17 cell subset and produced IFN-γ, IL-17A, and IL-22. This T cell subset was severely reduced in septic patients with K. pneumoniae bloodstream infection who also selectively lacked circulating K. pneumonie-reactive T cells. By combining heterologous antigenic stimulation, single cell cloning and TCR Vβ sequencing, we demonstrate that a large fraction of memory Th cell clones was broadly cross-reactive to several Enterobacteriaceae species. These cross-reactive Th cell clones were expanded in vivo and a large fraction of them recognized the conserved outer membrane protein A antigen. Interestingly, Enterobacteriaceae broadly cross-reactive T cells were also prominent among in vitro primed naïve T cells. Collectively, these data point to the existence of immunodominant T cell epitopes shared among different Enterobacteriaceae species and targeted by cross-reactive T cells that are readily found in the pre-immune repertoire and are clonally expanded in the memory repertoire.

Salmonella Biofilm Formation, Chronic Infection, and Immunity Within the Intestine and Hepatobiliary Tract

Within the species of Salmonella enterica, there is significant diversity represented among the numerous subspecies and serovars. Collectively, these account for microbes with variable host ranges, from common plant and animal colonizers to extremely pathogenic and human-specific serovars. Despite these differences, many Salmonella species find commonality in the ability to form biofilms and the ability to cause acute, latent, or chronic disease. The exact outcome of infection depends on many factors such as the growth state of Salmonella, the environmental conditions encountered at the time of infection, as well as the infected host and immune response elicited. Here, we review the numerous biofilm lifestyles of Salmonella (on biotic and abiotic surfaces) and how the production of extracellular polymeric substances not only enhances long-term persistence outside the host but also is an essential function in chronic human infections. Furthermore, careful consideration is made for the events during initial infection that allow for gut transcytosis which, in conjunction with host immune functions, often determine the progression of disease. Both typhoidal and non-typhoidal salmonellae can cause chronic and/or secondary infections, thus the adaptive immune responses to both types of bacteria are discussed with particular attention to the differences between Salmonella Typhi, Salmonella Typhimurium, and invasive non-typhoidal Salmonella that can result in differential immune responses. Finally, while strides have been made in our understanding of immunity to Salmonella in the lymphoid organs, fewer definitive studies exist for intestinal and hepatobiliary immunity. By examining our current knowledge and what remains to be determined, we provide insight into new directions in the field of Salmonella immunity, particularly as it relates to chronic infection.

A dual-therapy approach for the treatment of biofilm-mediated Salmonella gallbladder carriage

Asymptomatic carriage of Salmonella Typhi continues to facilitate the transmission of typhoid fever, resulting in 14 million new infections and 136,000 fatalities each year. Asymptomatic chronic carriage of S. Typhi is facilitated by the formation of biofilms on gallstones that protect the bacteria from environmental insults and immune system clearance. Here, we identified two unique small molecules capable of both inhibiting Salmonella biofilm growth and disrupting pre-formed biofilm structures without affecting bacterial viability. In a mouse model of chronic gallbladder Salmonella carriage, treatment with either compound reduced bacterial burden in the gallbladder by 1–2 logs resulting in bacterial dissemination to peripheral organs that was associated with increased mortality. Co-administration of either compound with ciprofloxacin not only enhanced compound efficacy in the gallbladder by a further 1–1.5 logs for a total of 3–4.5 log reduction, but also prevented bacterial dissemination to peripheral organs. These data suggest a dual-therapy approach targeting both biofilm and planktonic populations can be further developed as a safe and efficient treatment of biofilm-mediated chronic S. Typhi infections.

Typhoid fever is an infectious disease caused by Salmonella Typhi (S. Typhi), a bacterium that causes as many as 14 million new infections and 136,000 deaths annually. Asymptomatic chronic carriers of S. Typhi play a major role in the transmission of typhoid fever, as they intermittently shed the bacteria and can unknowingly infect surrounding individuals. Here, we characterized novel compounds that target biofilm formation, a process utilized by S. Typhi to establish and maintain chronic carriage in the gallbladder, in hopes that they may be eventually used in conjunction with traditional antibiotics to prevent and/or cure chronic infections more efficiently than antibiotics alone.

EmhR is an indole-sensing transcriptional regulator responsible for the indole-induced antibiotic tolerance in Pseudomonas fluorescens

Indole is well known as an interspecies signalling molecule to modulate bacterial physiology; however, it is not clear how the indole signal is perceived and responded to by plant growth promoting rhizobacteria (PGPR) in the rhizosphere. Here, we demonstrated that indole enhanced the antibiotic tolerance of Pseudomonas fluorescens 2P24, a PGPR well known for its biocontrol capacity. Proteomic analysis revealed that indole influenced the expression of multiple genes including the emhABC operon encoding a major multidrug efflux pump. The expression of emhABC was regulated by a TetR-family transcription factor EmhR, which was demonstrated to be an indole-responsive regulator. Molecular dynamics simulation showed that indole allosterically affected the distance between the two DNA-recognizing helices within the EmhR dimer, leading to diminished EmhR-DNA interaction. It was further revealed the EmhR ortholog in Pseudomonas syringae was also responsible for indole-induced antibiotic tolerance, suggesting this EmhR-dependent, indole-induced antibiotic tolerance is likely to be conserved among Pseudomonas species. Taken together, our results elucidated the molecular mechanism of indole-induced antibiotic tolerance in Pseudomonas species and had important implications on how rhizobacteria sense and respond to indole in the rhizosphere.

Typhoid fever infection - Antibiotic resistance and vaccination strategies: A narrative review

Typhoid fever is a bacterial infection caused by the Gram-negative bacterium Salmonella enterica subspecies enterica serovar Typhi (S. Typhi), prevalent in many low- and middle-income countries. In high-income territories, typhoid fever is predominantly travel-related, consequent to travel in typhoid-endemic regions; however, data show that the level of typhoid vaccination in travellers is low. Successful management of typhoid fever using antibiotics is becoming increasingly difficult due to drug resistance; emerging resistance has spread geographically due to factors such as increasing travel connectivity, affecting those in endemic regions and travellers alike. This review provides an overview of: the epidemiology and diagnosis of typhoid fever; the emergence of drug-resistant typhoid strains in the endemic setting; drug resistance observed in travellers; vaccines currently available to prevent typhoid fever; vaccine recommendations for people living in typhoid-endemic regions; strategies for the introduction of typhoid vaccines and stakeholders in vaccination programmes; and travel recommendations for a selection of destinations with a medium or high incidence of typhoid fever.

Predictive evaluation of pediatric patients based on their typhoid fever status using linear discriminant model

Epidemiologic studies have established a relationship between pediatric patients and typhoid fever infection. This study was carried out to ascertain if specific hematological measurements of the pediatric patients discriminate between their positive and negative status to typhoid infection and to produce a rule for classifying other pediatric patients. Discriminant analysis was applied to predict the probability of a specific categorical outcome based on several explanatory variables (predictors). This study analyzed the differentiation between two hundred pediatric patients attending Landmark University Medical Centre based on their typhoid fever status. The hematological parameters considered were Packed Cell Volume, White Blood Cell count; Neutrophil, Erythrocyte level, Hemoglobin and Platelet count, Assay of samples were performed using standard procedures. Fisher's Linear Discriminant Method was used for classification of variables in this study. With the use of the Fisher's Linear Discrimination method for classification of the obtained data, a minimum value of -0.0067 was obtained implying that any new pediatric patient with a discriminant score above -0.0067 would be diagnosed to be typhoid negative; otherwise, they would be classified as typhoid positive pediatric patients. The efficiency of this method of classification was tested using two approaches; Retribution estimate approach and leaving-one out approach which showed a prevalence rate of typhoid positive patients at 75.8% and 74.7% respectively. This data analysis hypotheses that typhoid fever is highly endemic amongst our study subjects. A point-of-care diagnosis with a strong positive predictive value, which improves pediatric enteric fever diagnosis, is strongly advocated.

A retrospective study of patients with blood culture-confirmed typhoid fever in Fiji during 2014-2015: epidemiology, clinical features, treatment and outcome

Background

Typhoid fever is endemic in Fiji. We sought to describe the epidemiology, clinical features and case fatality risk of blood culture-confirmed typhoid fever from January 2014 through December 2015.

Methods

Blood culture-positive patients were identified from a typhoid surveillance line list. A standardised case investigation form was used to record data from patients’ medical records.

Results

Of 542 patients, 518 (95.6%) were indigenous Fijians (iTaukei) and 285 (52.6%) were male. The median (IQR) age was 25 (16–38) y. Mean (SD) time from the onset of illness to admission was 11.1 (6.9) d. Of 365 patients with clinical information, 346 (96.9%) had fever, 239 (66.9%) diarrhoea, 113 (33.5%) vomiting, and 72 (30.2%) abdominal pain. There were 40 (11.0%) patients with complications, including 17 (4.7%) with shock, and 11 (3.0%) with hepatitis. Nine patients died for a case fatality risk of 1.7%. Of the 544 Salmonella Typhi isolates tested, none were resistant to first line antimicrobials; 3(0.8%) were resistant to ciprofloxacin and 5(1.4%) to nalidixic acid.

Conclusions

In Fiji, most blood culture-confirmed typhoid fever cases were in young adults. Common clinical manifestations were fever and gastrointestinal symptoms. Further studies are required to elucidate the factors associated with complications and death.

Salmonella Infection Among Food Handlers at Canteens in a Campus

Background:

Salmonella is one of the pathogenic microorganisms that can contaminate food through cross-contamination (less hygiene of handlers and environment). In a campus, food management and food handlers have a very important role in the contamination of microorganisms, which can lead to the incidence of foodborne diseases.

Objective:

This study aimed to assess the incidence of salmonella infections among food handlers at a campus canteen in Depok City, Indonesia.

Methods:

The cross-sectional study was conducted in May-June 2017. The population of this study was all food handlers working in the canteen (N=260). The data were obtained through interviews and observation of the characteristics and behaviors of the food handlers. Blood samples were also collected from 49 food handlers (n=49).

Results:

This study revealed that 61.2% of food handlers included in the age group were not at risk, the proportion of female food-handlers was slightly more than men (51%), the majority of them were low educated (59.2%), and all respondents had never given typhoid immunization. The results of the fecal examination revealed that two food handlers had typhoid. In addition, the behavior and personal hygiene of most of the handlers are poor. Environmental factors such as canteen sanitation facilities are mostly qualified, and most of the food handlers have no history of contact with animals.

Conclusion:

There was no statistically significant relationship between characteristics, behavior, personal hygiene, sanitation facilities, and contact history with animals against pathogenic bacterial infections.