Occurrence of Salmonella Enteric Serovar Typhi Antibodies among Blood Donors in Ghana

Background: Donated blood contaminated with S. Typhi can cause post-transfusion sepsis. This study aimed to determine the correlation between some risk factors of typhoid fever and seroprevalence of antibodies against S. Typhi among blood donors. Methodology: Following informed consent, socio-demographic and information on risk factors of typhoid infection was obtained using pre-structured questionnaires from 400 apparently healthy blood donors at the Tema General Hospital. Blood was also collected for serology and cultured for identification of pathogens by standard bacteriological method. Results: Blood culture did not reveal any S. Typhi isolate out of the tested 400 (348 males and 52 females) samples from apparently healthy blood donors. However, IgM and IgG antibody seroprevalence of 9.3% and 3.5% were detected. Age group of 17 - 24 years was the highest risk group, persons with a history of typhoid infection, and sources of drinking water were major risk factors for typhoid infection. It was also observed that prevalence of IgM was highest among new donors (62.2%), but lower in donors with a history of 1 to 3 blood donations (32.4%) and least among regular donors (>3 donations (5.4%)). In addition, typhoid prevention awareness and typhoid knowledge (knowledge about typhoid transmission) among the donors were poor (4.3% and 5.9% respectively). Conclusions: This study has shown an overall seroprevalence of 9% and 3.5% for IgM and IgG antibodies respectively among blood donors in the Tema area in Ghana. We advocate for the mandatory screening of donor units intended for transfusion for S. Typhi. Furthermore, there is an urgent need for the health education of all persons in Ghana on preventive measures and the spread of S. Typhi.

Prevalence and Antimicrobial Susceptibility Patterns of Escherichia Coli and Salmonella Typhi Isolated from Meat and Fish Samples from Selected Markets in a Metropolis and District in Ghana

Antimicrobial resistance has become a major challenge to the treatment and prevention of infections resulted in high morbidity and mortality globally. The inappropriate or abuse of antibiotics in animal farming is a key factor and thus led to the emergence of bacteria resistance and subsequent transfer of resistance genes to humans through the food chain. This study was to determine the prevalence of Salmonella typhi (S. typhi) and Escherichia coli (E. coli) isolated from various meat and fish samples and their susceptibility patterns against five commonly used antibiotics in Ghana (Ciprofloxacin 5 μg, Amoxicillin-clavulanic acid 20/10 μg, Imipenem 10 μg, Tetracycline 30 μg and Ceftazidime 30 μg). A total of 105 meat and fish samples were obtained from Tema and Prampram markets and bacteria isolation was carried out using appropriate selective microbial culture media and various biochemical methods for identification. The susceptibility patterns were determined using the Kirby-Bauer disk diffusion method and the results were interpreted using the CLSI 2020 guidelines. The results revealed a total of 56 bacterial isolates comprising 14 E. coli (25%) and 42 S. typhi (75%) isolated from the meat and fish samples. The antibiogram study showed a high resistance rate (88.64%) of S. typhi isolates to amoxicillin-clavulanic acid and tetracycline (97.73%). A moderate susceptibility of the isolates was obtained with imipenem (53.27%). All the E. coli isolates were resistant to tetracycline (100%) and demonstrated 78.57% and 50% resistance to amoxicillin-clavulanic acid and ceftazidime respectively. A total of 78.57% of the E. coli isolates and 68.18% of S. typhi isolates showed multidrug resistance. The multiple antibiotic resistance (MAR) index for all the isolates ranged from 0.2 to 1.00 with two S. typhi isolates and one E. coli isolate having a MAR index of 1.00 signifying total resistance to all the 5 antibiotics tested. In conclusion, E. coli and S. typhi isolated from the meat samples exhibited high rate of resistance against the antibiotics tested and thus possesses a major health risk due to inappropriate use of antibiotics in animal and fish farming and possible transfer of resistant strains to humans.

Salmonella typhi and gallbladder cancer:report from an endemic region

BACKGROUND:Evidence exists of a link between chronic infection by Salmonella typhi(S.typhi) and the development of gallbladder cancer(GBC),but several studies from endemic regions contradict its role in the etiopathogenesis of GBC.This study used various tools to assess the prevalence of S.typhi in patients with GBC and gallstone disease(GSD) in this region with a high incidence of GBC.METHODS:S.typhi was detected in tissue and bile by PCR and culture and in serum by the Widal test and indirect hemagglutination assay(IHA).PCR with two pairs of S.typhi specific primers(flagellin gene H1d and SOP E gene) could detect 0.6 ng of S.typhi DNA.Fifty-four patients with GBC(cases) were matched with 54 patients with GSD(controls).RESULTS:Of the 54 cases,24(44.44%) were positive on the Widal test and 12(22.22%) on IHA,compared to 13(24.07%) and 5(9.26%) respectively in the controls.Eighteen(33.33%) cases showed a positive result on PCR(tissue) and 2 on PCR(bile) vs.none in the controls.Bile culture revealed no Salmonella colonies in either cases or controls.Only 3 cases were positive for Salmonella on tissue culture compared to none in the controls.The sensitivity of PCR(tissue) relative to the Widal test,IHA,culture(bile and tissue) and PCR(bile) was 100% vs.66.67%,11.11%,and 11.11%,and the specificity was 83.33% vs.100%,100%,and 100%,respectively.CONCLUSIONS:S.typhi is significantly associated with GBC compared to GSD(33% vs.0%).PCR appears to be the most specific diagnostic tool,the gold standard for S.typhi in tissue samples.

Induction of deletion mutation on ompR gene of Salmonella enterica serovar Typhi isolates from asymptomatic typhoid carriers to evolve attenuated strains for vaccine development

Objective:To develop allenualed slrains of Salmonella enterica serorar Typhi(S.typhi) for the candidate vaccine by osmolar stress.Mothods:S.typhi SS3 and SS5 strains were isolated from asymptomatic typhoid carriers in Mamakkal,Tamil Nadu.India.Both strains were grown in LB(Luria Bertani) medium supplemented with various concentration of NaCl(0.1- 0.7M) respectively.The effecl of osmolar stress was determined at molecular level by PCR using MCR 06 and MCR07 primers corresponding to ompR with chromosomal DNA of S.typhi SS3 and SS5 strains.Attenuation by osmolar stress results in deletion mutation of the.S.typhi slrains was determined by agglutination assays,precipitation method.SDS PAGE analysis and by animal models.Results:The 799 bp amplified ompR gene product from wild type S.typhi SS3 and SS5 illustrate the presence of virulent gene.Interestingly,there was only a 282 bp amplified product from S.typhi SS3 and SS5 grown in the presence of 0.5.0.6 and 0.7 M NaCl.This illustrates the occurrence of deletion mutation in ompR gene al high concentration of NaCl.Furthermore,both the wildtype and mutant S.typhi outer membrane SDS-PAGF.profile reveals the differences in the expression of ompF.ompC and ompA proteins.In mice,wild type and mutant strains lethal dose(LD_(50)) were determined.The mice died within 72 h when both the wild type strains were injected intraperitoneally with 3 log CFU-mL^(-1).When the mice were injected with the mutants in same dosage,no clinical symptoms were observed;whereas the serum antibodv litre was elicited within two weeks indicated that the mutants have the ability to induce protective humoral immune response.These results suggest that S.typhi SS3 and SS5 may bo used as good candidate strains for the development of live attenuated vaccine against salmonellosis.Conclusions:This study demonstrates that the S.typhi strains were allenualed and could be good vaccine candidates in future.

Comparative Study on Bactericidal Effect of Silver Nanoparticles, Synthesized Using Green Technology, in Combination with Antibiotics on Salmonella Typhi

In this work bactericidal study of silver nanoparticles was taken up in combination with two standard antibiotics, ampicillin and gentamycin, for Salmonella Typhi. The antibacterial activities of antibiotics were increased in the presence of AgNPs against test strains. The higher enhancing effect was observed for ampicillin in comparison to gentamicin against test strains. Silver nanoparticles were synthesized elctrolytically using silver wire of 99% purity as anode and carbon rod wrapped with LDPE as cathode. Silver nitrate [of Merck] of 0.01N is used as an electrolyte. Here tea extract is added as capping and mild reducing agent. The polyphenols theaflavins and thearubigins, present in tea perform the role of stabilizing or capping agents due to their bulky and steric nature. A brown coloured colloidal solution of silver nanoparticles is obtained. The as-synthesized silver nanoparticles were characterized using XRD, TEM and UV-Vis spectroscopy.

Salmonella typhi infection in a tertiary institution in Nasarawa State,Nigeria

Objective:To evaluate the prevalence of Sabmonella typhi(S.typhi) among subjects attending College of Education Health Clinic,Akwanga,Nasarawa state from the year.2005 to 2007 and to recommend some preventive measures to the populace.Methods:Blood samples were tested for infection using the widal test.Results:Out of the 793 patients examined,579(73.0%) were positive with 174(30.05%),254(43.86%) and 151(26.07%) for the years 2005,2006 and 2007 respectively. The age range with the highest prevalence of infection for the period was 21-30 with 207(35.75%) followed by 31-40 year group with 133(22.97%).Chi-square analysis showed no significant difference in infection between males and females(P】0.05).Conclusions:The results of this study provide a useful guide in the formulation of S.typhi control measures in tertiary institutions in the State and also help to check the spread of the pathogen in the general population.

Enhancing chloramphenicol and trimethoprim in vitro activity by Ocimum sanctum Linn.(Lamiaceae) leaf extract against Salmonella enterica serovar Typhi

Objective:To evaluate the antibacterial activity of Ocimum sanctum(O.sanctum) leaf extract, alone,and in combination with chloramphenicol(C) and trimethoprim(Tm) against Salmonella enterica serovar Typhi(S.typhi).Methods:The antibacterial activity of ethanolic extract of tulsi, 0.sanctum,leaf(TLE:500μg) for 23 S.typhi isolates was determined following agar diffusion. The C(30μg) and Tm(5μg) activity alone and in combination with TLE(250μg) was determined by disk diffusion.The zone diameter of inhibition(ZDI) for the agents was recorded, and growth inhibitory indices(Glls) were calculated.Results:The S.typhi isolates(n=23),which were resistant to both C(ZDI 6 mm) and Tm(ZDI 6 mm),had TLE(500μg) ZDIs 16-24 mm.The ZDIs of C and Tm were increased up to 15-21 mm and 17-23 mm,respectively,when TLE(250μg) was added to the C and Tm discs.The Glls ranged 0.789-1.235 and 0.894-1.352,due to combined activity against S.typhi isolates,of C and TLE and Tm and TLE.respeclivelv.Conclusions:The data suggest that TLE,in combination with C and Tm,had synergistic activity for S.typhi isolates, and hence O.sanclum is potential in combating S.typhi drug resistance,as well promising in the development of non-antibiotic drug for S.typhi infection.

A cross sectional study on antibiotic resistance pattern of Salmonella typhi clinical isolates from Bangladesh

Objective:To investigate and compare the resistance and sensitivity of Salmonella typhi samples to commonly used antibiotics in three major divisions of Bangladesh and to evaluate the gradually developing resistance pattern.Methods:The antibiotic susceptibility of 70 clinical isolates collected from blood,sputum,urine and pus samples were identified by specific antisera and with standard biochemical tests.The patients were divided into 5 age groups.Susceptibility and resistance was also tested by KirbyBauer disc-diffusion method using 12 regularly used antibiotics.Results:Antibiotic susceptibility test demonstrated that 64.28%isolates of Salmonella typhi were multidrug resistant.Present study suggests that the clinical samples were mostly resistant against nalidixic acid with all age groups and in all three divisions with similar resistance pattern.Resistance is more common among adult people(30-40 years)and children(0-10 years).Salmonella typhi was mostly sensitive against gentamycin,chloramphenicol and ciprofloxacin.Conclusions:Although the population density of Dhaka region is markedly higher than Rajshahi and Chittagong regions,no significant difference in resistance pattern was found.The rate of multidrug resistance is a matter of concern.Physicians should reconsider before prescribing nalidixic acid and cefixime.Further molecular study is needed to reveal the genomic and proteomic basis of resistance.

Identification of a toxin coding fragment in pBSSB1, a linear plasmid from Salmonella enterica serovar Typhi that can stabilize a multicopy plasmid

Objective: To identify the region conferring stability to pBSSB2(a linear plasmid, pBSSB1, containing a kanamycin cassette), which is unique to Indonesian isolates of Salmonella enterica serovar Typhi. Methods: The open reading frame(ORF) 009 was identified as a toxin coding gene in the plasmid through introduction of translational termination codons in the ORF. Results: The stability function was located in a fragment that spanned nucleotides 5 766 to 6 828 in the linear plasmid genetic map. Ectopic expression of ORF009 in pBAD18 vector indicated ORF009 codes for a toxin. This fragment could stabilize plasmid pUC18 previously destabilized through mutation of the pcnB(plasmid copy number control) gene that codes for polyA polymerase. Majority of the cells expressing ORF009 were non-viable according to phase contrast microscopy. Conclusions: This study demonstrated that a linear plasmid fragment that carries a gene encoding a toxin possibly conferred stability to the parent plasmid. It was able to stabilize a multicopy plasmid of Escherichia coli.

Extensively drug-resistant Salmonella typhi causing rib osteomyelitis: A case report

Rationale:Salmonella(S.)typhi is a rare cause of osteomyelitis in immunocompetent adults.Extensive drug resistance(XDR)may lead to more complicated cases of S.typhi osteomyelitis.Patient concern:A 55-year-old female presented with a persistent low-grade fever and a swelling on her lower left chest with a sinus discharging purulent fluid for the past 8 months.Her symptoms had been unresponsive to previous anti-microbial therapy.Diagnosis:Rib osteomyelitis caused by XDR S.typhi.Interventions:Surgical wound debridement,left 7th-9th rib resection and intravenous Ⅳ meropenem were done.Outcome:Fever resolved and left-sided swelling resected without recurrence.Lessons:The prevalence of XDR S.typhi is growing in South Asia and should be considered as the differential diagnosis of chronic osteomyelitis.

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℃)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.

Effect of <i>Chromolaena odorata</i>Extracton Hematotoxicity and Spleen Histopathology Induced by <i>Salmonella typhi</i>in Wistar Rats

Salmonella typhi is a facultative intracellular pathogen that causes typhoid fever in humans. In the present study, the effect of Salmonella typhi infection on hematological indices and spleen histology in Wistar rats was investigated and was followed by an evaluation of the ameliorative potential of the methanol leaf extract of Chromolaena odorata (MLECO) compared with ciprofloxacin treatment. The animals were divided into six groups: group 1 was normal control, group 2 was infected with Salmonella typhi without treatment (negative control), groups 3, 4 and 5 were Salmonella typhi infected and treated with 100 mg/kg, 200 mg/kg and 400 mg/kg of the extract respectively and group 6 was also Salmonella typhi infected and treated with 500 mg/70kg of ciprofloxacin. The animals were inoculated with a single infectious dose of Salmonella typhi bacteria and thereafter, treated with the extract and ciprofloxacin for a period of seventeen days, after the animals were confirmed infected. The rats were humanely sacrificed and blood samples taken for haematological investigations, and the spleen harvested and processed for histological examinations. Chromolaena odorata administration reversed the adverse hematotoxicity and histopathological changes in the spleen induced by?Salmonella typhi?infection.

Analysis of Trends in Resistance to Fluoroquinolones and Extended Spectrum Beta-Lactams among <i>Salmonella</i>Typhi Isolates Obtained from Patients at Four Outpatient Clinics in Nairobi County, Kenya

Typhoid fever caused by the bacterium Salmonella enterica serovar Typhi (S. Typhi) causes an estimated 25 million illnesses and approximately 200,000 deaths annually mostly in developing countries. Although the management of typhoid fever has been effectively through antibiotic treatment, S. Typhi is increasingly becoming resistant to the currently recommended drugs. This study utilized a quasi-experimental design focusing on archived samples to describe antimicrobial susceptibility patterns of S. Typhi and determine the genetic basis of resistance to the two most commonly used classes of antimicrobials. A total sample size of 287 isolates of S. Typhi isolates stored in -80°C freezer at the Centre for Microbiology Research was utilized. Isolates were subjected to anti-microbial susceptibility testing to commonly available antimicrobials using disk diffusion method, then analyzed for trends in resistance to fluoroquinolones and extended spectrum beta lactams. Among the 287 isolates 158 (55.5%) were found to be Multi Drug Resistant (MDR). This implied that these isolates were resistant to all first line classes of treatment such as ampicillin, chloramphenicol and sulfamethoxazole-trimethroprim. In addition to this, these isolates were also resistant to at least one of the currently recommended drugs of choice, either a β-lactam or a fluoroquinolone. This study observed resistances at 18.2% and 15.4% to fluoroquinolones and cephalosporins respectively. PCR results revealed presence of blaTEM, blaINT and blaCTX-M genes coding for resistance to β-lactams in 80% of the isolates that had combined resistance to β-lactams and fluoroquinolones. It is likely that recent heavy use of these classes of antimicrobials is driving resistances to these antimicrobials.

Resistance to Fluoroquinolones and Other Antimicrobials in Culture-Positive <i>Salmonella typhi</i>Isolates in Gulbarga, South India

Background: Typhoid fever is a major public health concern in developing countries. The upsurge in the occurrence of bacterial isolates that are resistant to nalidixic acid;with reduced susceptibility to ciprofloxacin in typhoidal Salmonellae constitutes a challenge to the clinician. Methods: In order to better understand the epidemiology of Salmonella infections in South India, Salmonella typhi isolates were screened from various healthcare centers. Salmonella isolates were identified by using standard phenotypic, serological, antibiotic susceptibility and molecular methods. Results: Among a total of 100 S. typhi isolates 9% were found to be multidrug resistant and 30% were nalidixic acid resistant. Isolates with reduced susceptibility to ciprofloxacin displays single base mutations in the gyrA gene. A very low rate of 1% resistance was found to ciprofloxacin. The only one isolate with ciprofloxacin MIC ≥ 4 μg/ml also showed single mutation in the QRDR of the gyrA gene in S. typhi (GenBank accession no. HQ176349-HQ176368). Conclusions: A very low rate of nalidixic acid resistance with reduced susceptibility to ciprofloxacin was observed in comparison to other endemic areas in isolates of S. typhi from Gulbarga, South India, with steadily increasing NAR S. typhi but decreasing MDR isolations over the study period. This is most likely due to an increased use of ciprofloxacin as a first line drug of choice over more traditional antimicrobial agents for the treatment of typhoid fever.

Isolation of Multi-Drug Resistant (MDR) and Extensively Drug Resistant (XDR) <i>Salmonella typhi</i>from Blood Samples of Patients Attending Tertiary Medical Centre in Dhaka City, Bangladesh

Objective: Almost all year round occurrence of typhoid fever remains a major public health issue in Bangladesh. In recent years, there has been a significant rise in the prevalence of multi-drug resistance Salmonella typhi in Dhaka city. The major objective of this study was to observe the prevalence of multi-drug and Extended drug-resistant patterns of typhoidal Salmonella typhi among the patients attending a tertiary medical center by conventional culture and serologic test. Materials and Methods: Blood was collected by syringe and equally divided between aerobic & anaerobic BacT Alert bottle, 10 mL for paediatrics. Post isolation Salmonella strains were identified and were tested for antibiotic resistance. Results: A total of 600 blood samples of typhoid suspected patients were tested, where 32.5% came out positive, which were identified as Salmonella typhi. These isolates were susceptible to carbapenem drugs but highly resistant to Fluoroquinolones and Aminoglycosides antibiotics. Discussion: It was seen that 73.23% of isolates among male patients were extensively drug-resistant (XDR) meaning that isolates were sensitive against only one or two antibiotics while in the female it was 58.46%. Isolates from Female patients showed higher multi-drug resistant (MDR) (26.15%) isolates resistance to multiple antibiotics in comparison to isolates from the male (16.54%). 87.19% of the strains showed high drug resistance (XDR and MDR). Conclusion: The emergence of XDR and MDR strains of S. typhi in recent years is becoming a significant threat. Although no PAN-Drug resistance (resistant against all tested drugs) was observed in the current study, a high level of XDR and MDR isolates are indicating that the scenario might take place sooner than later.

伤寒沙门菌外膜囊泡通过调控铁死亡抑制结直肠癌细胞的增殖及机制初探

近年来,细菌外膜囊泡(OMVs)在抗肿瘤治疗中展现出的巨大潜力引起了广泛的关注.为探究伤寒沙门菌外膜囊泡(S.Typhi-OMVs)对人结直肠癌细胞株HT-29增殖的影响及可能的作用机制,通过超速离心法提取不同细菌的OMVs,细胞增殖实验(CCK-8)检测各细菌OMVs对细胞活力的影响;转录组测序(RNA-seq)分析处理后细胞基因表达水平的变化;试剂盒检测铁死亡相关标志物的含量变化;实时荧光定量PCR(qRT-PCR)和蛋白质免疫印迹法(western blot)分别检测相关基因mRNA和蛋白质的表达变化.结果显示,在提取的6种细菌OMVs中,S.Typhi-OMVs对HT-29细胞的增殖产生了最明显的抑制作用,并且呈现出浓度和时间梯度依赖性;RNA-seq显示HT-29细胞可能发生了铁死亡;S.Typhi-OMVs作用后,细胞内发生了铁沉积,氧化产物增多,抗氧化剂减少,符合铁死亡生化特征;SAT1是S.Typhi-OMVs处理后HT-29胞内mRNA表达量变化最大的基因;p53-SAT1-ALOX15是铁死亡的信号通路之一,S.Typhi-OMVs处理后胞内p53、SAT1、ALOX15的mRNA与蛋白表达均增高.以上结果表明,S.Typhi-OMVs能够抑制结直肠癌细胞HT-29的增殖,其机制可能与通过p53-SAT1-ALOX15信号通路诱导HT-29发生铁死亡有关.

Identification of in vivo induced protein antigens of Salmonella enterica serovar Typhi during human infection

During infectious disease episodes, pathogens express distinct subsets of virulence factors which allow them to adapt to different environments. Hence, genes that are expressed or upregulated in vivo are implicated in pathogenesis. We used in vivo induced antigen technology (IVIAT) to identify antigens which are expressed during infection with Salmonella enterica serovar Typhi. We identified 7 in vivo induced (IVI) antigens, which included BcfD (a fimbrial structural subunit), GrxC (a glutaredoxin 3), SapB (an ABC-type transport system), T3663 (an ABC-type uncharacterized transport system), T3816 (a putative rhodanese-related sulfurtransferase), T1497 (a probable TonB-dependent receptor) and T3689 (unknown function). Of the 7 identified antigens, 5 antigens had no cross-immunoreactivity in adsorbed control sera from healthy subjects. These 5 included BcfD, GrxC, SapB, T3663 and T3689. Antigens identified in this study are potential targets for drug and vaccine development and may be utilized as diagnostic agents.

Humanized mice are susceptible to Salmonella typhi infection

Salmonella enterica serovar Typhi is a pathogen that only infects humans.Currently,there is no animal model for studying this pathogen.Recently,alymphoid RAG2^(-/-)/γc^(-/-) mice engrafted with human leukocytes,known as humanized mice,have been successfully utilized to develop experimental models for several human-specific viral infections,including HIV,human-like dengue fever and hepatitis C virus.Little is known about the usefulness and feasibility of the humanized mouse model for the study of human-specific bacterial pathogens,such as S.typhi.The aim of this study was to determine if Salmonella enterica serovar Typhi could establish productive infection in humanized mice.Here we report that intravenous inoculation of S.typhi into humanized mice,but not controls,established S.typhi infections.High bacterial loads were found in the liver,spleen,blood and bone marrow of mice reconstituted with human leukocytes,but not in the unreconstituted control mice.Importantly,S.typhi-infected humanized mice lost significant body weight,and some of the infected mice displayed neurological symptoms.Our data suggest,for the first time,that humanized mice are susceptible to S.typhi challenge and that this model can be utilized to study the pathogenesis of S.typhito develop novel therapeutic strategies.

Antibiotic resistome of Salmonella typhi:molecular determinants for the emergence of drug resistance

Resistome is a cluster of microbial genes encoding proteins with necessary functions to resist the action of antibiotics.Resistome governs essential and separate biological functions to develop resistance against antibiotics.The widespread clinical and nonclinical uses of antibiotics over the years have combined to select antibiotic-resistant determinants and develop resistome in bacteria.At present,the emergence of drug resistance because of resistome is a significant problem faced by clinicians for the treatment of Salmonella infection.Antibiotic resistome is a dynamic and ever-expanding component in Salmonella.The foundation of resistome in Salmonella is laid long before;therefore,the antibiotic resistome of Salmonella is reviewed,discussed,and summarized.We have searched the literature using PubMed,MEDLINE,and Google Scholar with related key terms(resistome,Salmonella,antibiotics,drug resistance)and prepared this review.In this review,we summarize the status of resistance against antibiotics in S.typhi,highlight the seminal work in the resistome of S.typhi and the genes involved in the antibiotic resistance,and discuss the various methods to identify S.typhi resistome for the proactive identification of this infection and quick diagnosis of the disease.

艾滋病合并伤寒沙门菌硬膜下脓肿一例

硬膜下脓肿是指硬脑膜与蛛网膜下腔之间的脓肿,常由葡萄球菌、链球菌等引起,伤寒沙门菌引起的硬膜下脓肿罕见。该文报道了一例艾滋病患者,表现为发热、头痛的硬膜下脓肿,血培养、脑脊液高通量测序(NGS)均提示伤寒沙门菌感染,予基于药物敏感试验的敏感抗生素治疗结合外科引流的方法而治愈,引流物培养出伤寒沙门菌。术后4个月随访,患者症状消失,影像学无异常。该文提示,伤寒沙门菌引起的颅内感染罕见,可见于免疫功能低下人群,血培养、脓液培养和NGS对于鉴别该病原体感染有重要的价值,确诊后选用敏感抗生素结合外科治疗,可取得良好疗效。