Objectives:To assess the variations in hypertonic tolerance among Salmonella enterica serovar Newport(S.Newport)strains isolated from diverse sources and investigate the mechanism underlying the tolerance differences between the sensitive and tolerant strain.Materials and Methods:In this work,various S.Newport strains were cultured in 5%and 10%NaCl solutions(hypertonic stress),and the most sensitive and tolerant strains were selected using a Weibull model.The regulatory mechanisms underlying the hypertonic tolerance differences of S.Newport were preliminarily investigated in the aspects of cell phenotype,intracellular solute concentration,and gene expression level.Results:With prolonged hypertonic stress time,the leakage of nucleic acids and proteins of S.Newport increased gradually,and the membrane potential of S.Newport declined after increasing.Compared with the sensitive strain,the tolerant counterpart exhibited the ability to maintain the integrity of the cell membrane and sustain a high membrane potential level.The expression levels of the upstream genes proV and otsB in the tolerant strain were signifcantly lower than those in the sensitive strain;but the Kdp and Trk systems and downstream genes proX,proW,and otsA were highly expressed in the tolerant strain compared with the sensitive strain,leading to higher concentrations of intracellular K+and trehalose,enabling better survival in a hypertonic environment.Conclusions:The fndings of this work offer valuable insights into pathogen survival mechanisms under hypertonic stress and contribute to the development of strategies for mitigating microbiological risks during long-term processing and storage in the cured food industry.
Typhoid fever is an important health issue in developing countries,and the pathogenicity of Salmonella enterica serovar Typhi(S.ser.Typhi)depends on the presence of different virulence factors.Therefore,this study aimed to investigate the spread of virulence genes among S.Typhi isolates from patients with typhoid fever in Baghdad,Iraq.Sixty S.Typhi isolates were collected from several hospitals in Baghdad and identified using VITEK-II and confirmed by polymerase chain reaction(PCR)to detect the 16S rRNA gene.After testing their susceptibility to different antimicrobials(via the disk diffusion method),we found the highest resistance rates(100%)were to ampicillin,piperacillin,cefotaxime,and ceftriaxone.The highest sensitivity rates(100%)were to ertapenem,imipenem,meropenem,and sulfamethoxazole/trimethoprim.The presence of genes encoding for virulence in S.Typhi isolates was tested by conventional PCR.The results showed that out of 60 isolates,59(98.3%),59(98.3%),58(96.7%),and 60(100%)were positive for viaB,staA,cdtB,and orfL genes,respectively.The sequencing of PCR products(viaB,staA,cdtB,and orfL genes)was carried out at the Macrogen Company(Seoul,Korea).The sequences were compared with nucleotide sequences in the BLAST GenBank database,and data obtained from the sequencing of these virulence genes were submitted to GenBank under different accession numbers.A phylogenetic analysis of the 16S rRNA gene sequence found a high similarity between local sequences and the closely related sequences of genes in GenBank.The presence of the viaB,staA,cdtB,and orfL virulence genes in nearly all of the isolates under examination suggests that they play an important role in the pathogenicity of local isolates.
Muna Sabah DawoodNadheema Hammood HusseinKhetam Habeeb Rasool
Food- and water-borne diseases exacerbate cases of antimicrobial resistance (AMR), particularly in low- and middle-income countries. Since 2011, cases of enteric infections have been reported in Bukavu city, Democratic Republic of the Congo. The objectives of this study were to evaluate the rate of AMR and multidrug resistance (MDR) of Salmonella enterica and Escherichia coli, and to determine the effect of S. enterica and E. coli cohabitation on antibiotic resistance of S. enterica. Bacteria were isolated from 553 foods, milk, and water samples collected from restaurants, taps, tanks and wells in Bukavu. Microbial analyses involved bacterial culture, and morphological and biochemical characterization. Antibiotic susceptibility tests were performed before and after bacteria cohabitation of S. enterica and E. coli isolates in the same media. 152 (27.5%) and 27 (4.9%) of the samples tested positive for S. enterica and E. coli, respectively. Salmonella isolates were more susceptible to ciprofloxacin (75.7%) and co-trimoxazole (75.0%) and more resistant to ampicillin (82.2%). E. coli was more resistant to ciprofloxacin (59.3%). Overall, 90.5% of isolates (n = 179) were MDR. The origin (food, water) of S. enterica and E. coli isolates had no significant (p > 0.05) influence on their susceptibility to antibiotics. However, S. enterica isolates from milk were significantly (p = 0.00) antibiotic-resistant than those from food and water. The cohabitation between antibiotic-susceptible S. enterica and antibiotic-resistant E. coli significantly (p S. enterica from 30% to 89.5%, implying that interactions of antibiotic-resistant and antibiotic-susceptible bacteria in food and water could be among neglected factors promoting the spread of AMR, leading to increase AMR cases in Bukavu. Strong sanitation strategies and the operationalization of One Health approach could mitigate the spread of AMR in Bukavu city, DR Congo.
Alain M. OkitoJohn M. WagachaCatherine LukhobaGrace WaturuAlexi A. LinaWolfgang R. Mukabana
The objective of this study was to correlate the annual prevalence of cephems resistance and bla_(CMY-2) in Salmo-nella enterica using surveillance data in the United States.Using datasets retrieved from the surveillance programs of the United States National Antimicrobial Resistance Monitoring System(NARMS)for Enteric Bacteria from 2002 to 2018,we performed Spearman’s correlation analysis to correlate the annual prevalence data.We observed a near-perfect positive correlation in the annual prevalence between cefoxitin(ρ=0.97,P<0.0001),ceftiofur(ρ=0.96,P<0.0001),ceftriaxone(ρ=0.95,P<0.0001)resistance and bla_(CMY-2) in S.enterica recovered from chicken retail meat.Similarly,we observed a very high positive correlation in the annual prevalence between cefoxitin(ρ=0.94,P<0.0001),ceftiofur(ρ=0.91,P<0.0001),ceftriaxone(ρ=0.82,P<0.0001)resistance and bla_(CMY-2) in S.enterica recov-ered from turkey retail meat.Using Autoregressive Integrated Moving Average(ARIMA)modeling,the forecasted annual prevalence of beta-lactam resistance for the years 2019-2021 was similar to the NARMS-reported data for these periods.Correlation between the annual prevalence of cephems resistance and bla_(CMY-2) suggests either data can be used as a proxy for decision-making in retail meat surveillance programs.
BACKGROUND Secondary hemophagocytic lymphohistiocytosis(sHLH)triggered by Salmonella enterica serovar Typhimurium is rare in pediatric patients.There is no consensus on how to treat S.typhimurium-triggered sHLH.CASE SUMMARY A 9-year-old boy with intermittent fever for 3 d presented to our hospital with positive results for S.typhimurium,human rhinovirus,and Mycoplasma pneumoniae infections.At the time of admission to our institution,the patient’s T helper 1/T helper 2 cytokine levels were 326 pg/mL for interleukin 6(IL-6),9.1 pg/mL for IL-10,and 246.7 pg/mL for interferon-gamma(IFN-γ),for which the ratio of IL-10 to IFN-γwas 0.04.In this study,the patient received meropenem,linezolid,and cefoperazone/sulbactam in combination with high-dose methylprednisolone therapy(10 mg/kg/d for 3 d)and antishock supportive treatment twice.After careful evaluation,this patient did not receive HLH chemotherapy and recovered well.CONCLUSION S.Typhimurium infection-triggered sHLH patient had a ratio of IL-10 to IFN-γ≤1.33,an IL-10 concentration≤10.0 pg/mL,and/or an IFN-γconcentration≤225 pg/mL at admission.Early antimicrobial and supportive treatment was sufficient,and the HLH-94/2004 protocol was not necessary under these conditions.
