Non-typhoidal Salmonella Isolates Research Articles

Impact of COVID-19-related nonpharmaceutical interventions on diarrheal diseases and zoonotic Salmonella

Non-pharmaceutical interventions (NPIs) have been proven effective in reducing the spread of the coronavirus disease 2019 (COVID-19), but their broader impact on gastrointestinal disorders remains poorly studied. Here, we report an observational analysis and retrospective study that compares the incidence of acute diarrheal diseases in Hangzhou, Zhejiang, China, between 2019 and 2020, with an examination of the antimicrobial resistance and genetic spectrum of non-typhoidal Salmonella (NTS) from 2015 to 2022, before and during the COVID-19 pandemic. Our findings underscore that NPIs related to COVID-19 effectively reduced the incidence of acute diarrhea, with a substantial decrease in most enteric pathogens. Notably, NTS exhibited an unexpected surge. Further genomic investigations of NTS isolates revealed an overall reduction in antimicrobial-resistant (AMR), disinfection-tolerant, and virulent capabilities, but with marked variations detected between human and animal isolates. Additional genome-based analysis confirmed a decrease in the scale of zoonotic transmission in response to NPIs, suggesting particular NTS types may contribute to human infections via alternative pathways. The collective findings manifested that COVID-19-related NPIs had a mixed impact on NTS infections, which may inform AMR NTS mitigation policy.

Prevalence and dissemination of mcr-9.1-producing non-typhoidal Salmonella strains from diarrhea patients throughout China during 2010–2020

The emergence of mobilized colistin resistance (mcr) genes has raised significant concerns as they pose a public health issue. The prevalence of mcr genes, particularly the newly discovered mcr-9 gene, in non-typhoidal Salmonella (NTS) isolates remains unclear. We characterized mcr-9.1-producing NTS isolates from China. Among 7,106 NTS isolates from diarrhea cases in 32 provinces during 2010–2020, 11 mcr-9.1-producing isolates were identified and were all not resistant to colistin. Five isolates belonged to Salmonella Thompson and sequence type (ST) 26, two belonged to Salmonella Typhimurium and ST34, two belonged to Salmonella Typhimurium and ST36, and two belonged to Salmonella 1,4,[5],12:i:- and ST34. Plasmids harboring mcr-9.1 tended to possess the IncHI2 backbone and were ~ 300 kb long. All mcr-9.1 genes shared the same flanking sequence, rcnR-rcnA-pcoS-IS903-mcr-9.1-wbuC. According to the NCBI data, we found that NTS serves as the primary host of mcr-9.1, although the prevalence of specific serotypes differed between domestic and international settings. Notably, most data came from developed countries, such as the USA. mcr-9.1 tended to be transferred as a gene cassette or to be mobilized by a conjugational plasmid in multiple bacteria across humans, animals, and the environment. Furthermore, mcr-9.1 frequently co-existed and was co-transferred with various genes encoding resistance to first-line drugs, reducing the effectiveness of available therapeutic options. In summary, although mcr-9 does not mediate colistin resistance, it can silently spread with some genes encoding resistance to first-line drugs, and therefore warrants research attention.

Whole-Genome Sequencing Analysis of Non-Typhoidal Salmonella Isolated from Breeder Poultry Farm Sources in China, 2020-2021.

Non-typhoidal salmonellosis is a dangerous foodborne disease that causes enormous economic loss and threatens public health worldwide. The consumption of food, especially poultry or poultry products, contaminated with non-typhoidal Salmonella (NTS) is the main cause of human salmonellosis. To date, no research has identified the molecular epidemiological characteristics of NTS strains isolated from breeder chicken farms in different provinces of China. In our study, we investigated the antimicrobial resistance, phylogenetic relationships, presence of antimicrobial resistance and virulence genes, and plasmids of NTS isolates recovered from breeder chicken farms in five provinces of China between 2020 and 2021 by using a whole-genome sequencing (WGS) approach and phenotypic methods. All sequenced isolates belonged to six serovars with seven sequence types. Nearly half of the isolates (44.87%) showed phenotypic resistance to at least three classes of antimicrobials. Salmonella enterica serotype Kentucky harbored more antimicrobial resistance genes than the others, which was highly consistent with phenotypic resistance. Furthermore, the carried rate of 104 out of 135 detected virulence genes was 100%. Overall, our WGS results highlight the need for the continuous monitoring of, and additional studies on, the antimicrobial resistance of NTS.

The epidemiology of fecal carriage of nontyphoidal Salmonella among healthy children and adults in three sites in Kenya.

Despite the importance of non-Typhoidal Salmonella (NTS) disease in Africa, epidemiologic data on carriage and transmission are few. These data are important to understand the transmission of NTS in Africa and to design control strategies. To estimate the prevalence of stool carriage of NTS in Kenya, we conducted a cross-sectional study in Kilifi, Nairobi, and Siaya, sites with a low, moderate and high incidence of invasive NTS disease, respectively. At each site, we randomly selected 100 participants in each age-group of 0-11 months, 12-59 months, 5-14 years, 15-54 years and ≥55 years. We collected stool, venous blood (for hemoglobin and malaria rapid tests), anthropometric measurements, and administered a questionnaire on Water Access Sanitation and Hygiene (WASH) practices. Stool samples were cultured on selective agar for Salmonella; suspect isolates underwent serotyping and antimicrobial susceptibility testing. Overall, 53 (3.5%) isolates of NTS were cultured from 1497 samples. Age-adjusted prevalence was 13.1% (95%CI 8.8-17.4) in Kilifi, 0.4% (95%CI 0-1.3) in Nairobi, and 0.9% (95%CI 0-2.0) in Siaya. Prevalence was highest among those aged 15-54 years (6.2%). Of 53 isolates; 5 were S. Enteritidis, 1 was S. Typhimurium. No S. Typhi was isolated. None of the risk factors were associated with carriage of NTS. All isolates were susceptible to all antibiotics tested, including ampicillin, chloramphenicol, ciprofloxacin and co-trimoxazole. Prevalence of fecal carriage was high in Kilifi, an area of low incidence of invasive NTS disease and was low in areas of higher incidence in Nairobi and Siaya. The age-prevalence, risk factors, geographical and serotype distribution of NTS in carriage differs from invasive disease.

Persistence and dynamic structures of diverse cephalosporinase genes in nontyphoidal Salmonella in cross-sectional surveillance in Taiwan

Nontyphoidal Salmonella (NTS) is a major foodborne pathogen causing from acute gastroenteritis to bacteraemia, particularly in paediatric and elderly patients. Antimicrobial resistance of NTS, especially resistance to extended-spectrum cephalosporins, has emerged over the past decades. Thirteen NTS isolates resistant to ceftriaxone or cefotaxime were collected from a teaching hospital in Taipei, and another three from a tertiary hospital, in New Taipei City, Taiwan, from September 2018 to December 2019. Ten other archived isolates from 2000 to 2017 were also obtained. Complete genomes of the 26 isolates were obtained. Serovars, sequence types, resistomes, genetic relatedness, and sequence comparison of plasmids were analyzed. Serogroups B, C2 and E were significantly associated with ampicillin resistance. Over 90% of these 26 isolates are susceptible to carbapenems and colistin. Genomic epidemiology of these isolates shows that blaCMY-2-harbouring isolates in different serovars were prevalent over two decades, presumably resulting from highly mobile IncI1 plasmid harbouring blaCMY-2. One type of the IncI1 plasmids contained a mobile element, IS26, which might be involved in the acquisition of antimicrobial resistance genes. Two emerging serovars, S. Goldcoast ST358 harbouring blaCTX-M-55 on IncHI2 plasmids and S. Anatum ST64 harbouring blaDHA-1 on IncA/C2 plasmids persisted in Taiwan, possibly through the clonal spread. Integration of complete or partial plasmid sequences into host chromosomes or multiplications of the antimicrobial resistance genes also appears to be mediated by IS26, in the two emerging clones. The dynamic movement of cephalosporinase genes mediated by IS26 in NTS is of great concern.

Genomic diversity and epidemiological significance of non-typhoidal Salmonella found in retail food collected in Norfolk, UK.

Non-typhoidal Salmonella (NTS) is a major cause of bacterial gastroenteritis. Although many countries have implemented whole genome sequencing (WGS) of NTS, there is limited knowledge on NTS diversity on food and its contribution to human disease. In this study, the aim was to characterise the NTS genomes from retail foods in a particular region of the UK and assess the contribution to human NTS infections. Raw food samples were collected at retail in a repeated cross-sectional design in Norfolk, UK, including chicken (n=311), leafy green (n=311), pork (n=311), prawn (n=279) and salmon (n=157) samples. Up to eight presumptive NTS isolates per positive sample underwent WGS and were compared to publicly available NTS genomes from UK human cases. NTS was isolated from chicken (9.6 %), prawn (2.9 %) and pork (1.3 %) samples and included 14 serovars, of which Salmonella Infantis and Salmonella Enteritidis were the most common. The S. Enteritidis isolates were only isolated from imported chicken. No antimicrobial resistance determinants were found in prawn isolates, whilst 5.1 % of chicken and 0.64 % of pork samples contained multi-drug resistant NTS. The maximum number of pairwise core non-recombinant single nucleotide polymorphisms (SNPs) amongst isolates from the same sample was used to measure diversity and most samples had a median of two SNPs (range: 0-251). NTS isolates that were within five SNPs to clinical UK isolates belonged to specific serovars: S. Enteritidis and S. Infantis (chicken), and S. I 4,[5],12:i- (pork and chicken). Most NTS isolates that were closely related to human-derived isolates were obtained from imported chicken, but further epidemiological data are required to assess definitively the probable source of the human cases. Continued WGS surveillance of Salmonella on retail food involving multiple isolates from each sample is necessary to capture the diversity of Salmonella and determine the relative importance of different sources of human disease.

Whole genome sequencing of Salmonella enterica serovars isolated from humans, animals, and the environment in Lagos, Nigeria

BackgroundSalmonella infections remain an important public health issue worldwide. Some serovars of non-typhoidal Salmonella (NTS) have been associated with bloodstream infections and gastroenteritis, especially in children in Sub-Saharan Africa with circulating S. enterica serovars with drug resistance and virulence genes. This study identified and verified the clonal relationship of Nigerian NTS strains isolated from humans, animals, and the environment.MethodsIn total, 2,522 samples were collected from patients, animals (cattle and poultry), and environmental sources between December 2017 and May 2019. The samples were subjected to a standard microbiological investigation. All the isolates were identified using Microbact 24E, and MALDI-TOF MS. The isolates were serotyped using the Kauffmann-White scheme. Antibiotic susceptibility testing was conducted using the disc diffusion method and the Vitek 2 compact system. Virulence and antimicrobial resistance genes, sequence type, and cluster analysis were investigated using WGS data.ResultsForty-eight (48) NTS isolates (1.9%) were obtained. The prevalence of NTS from clinical sources was 0.9%, while 4% was recorded for animal sources. The serovars identified were S. Cotham (n = 17), S. Give (n = 16), S. Mokola (n = 6), S. Abony (n = 4), S. Typhimurium (n = 4), and S. Senftenberg (n = 1). All 48 Salmonella isolates carried intrinsic and acquired resistant genes such as aac.6…Iaa, mdf(A), qnrB, qnrB19 genes and golT, golS, pcoA, and silP, mediated by plasmid Col440I_1, incFIB.B and incFII. Between 100 and 118 virulence gene markers distributed across several Salmonella pathogenicity islands (SPIs), clusters, prophages, and plasmid operons were found in each isolate. WGS revealed that strains of each Salmonella serovar could be assigned to a single 7-gene MLST cluster, and strains within the clusters were identical strains and closely related as defined by the 0 and 10 cgSNPs and likely shared a common ancestor. The dominant sequence types were S. Give ST516 and S. Cotham ST617.ConclusionWe found identical Salmonella sequence types in human, animal, and environmental samples in the same locality, which demonstrates the great potential of the applied tools to trace back outbreak strains. Strategies to control and prevent the spread of NTS in the context of one’s health are essential to prevent possible outbreaks.

Prevalence ofSalmonellain Stool During the Vaccine Impact on Diarrhea in Africa (VIDA) Study, 2015–2018

Non-typhoidal Salmonella (NTS) is a common cause of gastroenteritis in young children, with limited data on NTS serovars and antimicrobial resistance in Africa. We determined the prevalence of Salmonella spp. and frequency of antimicrobial resistance among serovars identified in stools of 0-59 month-old children with moderate-to-severe diarrhea (MSD) and controls enrolled in the Vaccine Impact on Diarrhea in Africa (VIDA) Study in The Gambia, Mali, and Kenya in 2015-2018, and compared with data from the Global Enteric Multicenter Study (GEMS; 2007-2010) and the GEMS-1A study (2011). Salmonella spp. was detected by quantitative real-time PCR (qPCR) and culture-based methods. Identification of serovars was determined by microbiological methods. By qPCR, the prevalence of Salmonella spp. among MSD cases was 4.0%, 1.6%, and 1.9% and among controls was 4.6%, 2.4%, and 1.6% in The Gambia, Mali, and Kenya, respectively, during VIDA. We observed year-to-year variation in serovar distribution and variation between sites. In Kenya, Salmonella enterica serovar Typhimurium decreased (78.1% to 23.1%; P < .001) among cases and controls from 2007 to 2018, whereas serogroup O:8 increased (8.7% to 38.5%; P = .04). In The Gambia, serogroup O:7 decreased from 2007 to 2018 (36.3% to 0%; P = .001) but S. enterica serovar Enteritidis increased during VIDA (2015 to 2018; 5.9% to 50%; P = .002). Only 4 Salmonella spp. were isolated in Mali during all 3 studies. Multidrug resistance was 33.9% in Kenya and 0.8% in The Gambia across all 3 studies. Ceftriaxone resistance was only observed in Kenya (2.3%); NTS isolates were susceptible to ciprofloxacin at all sites. Understanding variability in serovar distribution will be important for the future deployment of vaccines against salmonellosis in Africa.

Molecular Characterization of Non-typhoidal Salmonella (NTS) Isolated from Salad Vegetables in Terengganu, Malaysia

Salad vegetables are the important sources of vitamins and minerals for human diet. However, salad vegetables are potential vehicles for non-typhoidal Salmonella spp. (NTS) as reported in our previous study. Such contamination posed significant food poisoning risk to consumer. The aims of present study include determination of the virulence genes prevalence in NTS isolates in samples from retail markets and farms. Besides, characterization of NTS isolates was performed to determine their genetic relatedness. Multiplex PCR assay was done to detect the presence of 15 virulence genes in 58 NTS isolates. The genetic relatedness of 33 NTS belonging to S. Weltevreden, S. Albany, S. Hvittingfoss, S. Aberdeen, S. Poona and S. Corvallis were characterized using ERIC-PCR and BOX-PCR typing methods. Results showed the presence of 13 virulence genes (spiA, pagC, msgA, invA, sipB, prgH, spaN, orgA, tolC, sitC, lpfC, sifA and sopB) among all the isolates with 53 (91.38%) isolates carried more than 11 virulence genes, while other five isolates carried the genes in the range of six to nine types. None of the isolates possessed spvB and pefA genes. Major clusters were observed at a genetic distance percentage of 90% for both ERIC- and BOX-PCR with discriminatory index of 0.917 and 0.873, respectively. In terms of source and type of sample, all NTS isolates were found diverse without clear association, thus no specific cluster was found. In summary, this study demonstrated the potential risks of NTS from salad vegetables to cause foodborne diseases and they were commonly found to be related with regard to their specific serovars.

NON-TYPHOIDAL SALMONELLA: A HOSPITAL BASED STUDY FROM SOUTH INDIA

Background &amp; objectives: The objective of this study was to evaluate the prevalence of Non-typhoidal Salmonella and to nd their antibiotic susceptibility pattern in a tertiary care hospital in South India. A signicant global health issue is the steadily rising percentage of Non-typhoidal Salmonella (NTS) infections in people. A descriptive study was conducted at Methods: a tertiary care teaching hospital in South India. Culture and sensitivity of stool samples of clinically suspected patients were done in the Microbiology laboratory from Sree Gokulam Medical College and Research Foundation. All samples were inoculated onto appropriate culture plates. Colonies suspected as Salmonella were identied by standard laboratory methods, initially by manual biochemical tests and by the VITEK-2 automated systems (bioMérieux) and nal serotyping by polyvalent antisera. 3 of the Salmonella isolates were sent to CMC, Vellore, India for serotyping. Antibiotic susceptibility tests were performed by Kirby Bauer's disc diffusion method on Mueller-Hinton agar and results were interpreted as per the CLSI guidelines (2022). Signed informed consent was obtained from all participants. Tests were performed in the clinical Microbiology Laboratory under the Department of Microbiology, Sree Gokulam Medical College and Research Foundation, Venjaramoodu, Trivandrum. Of the 244 mot Results: ion samples, Non-typhoidal Salmonella isolated were from 20 motion samples. The predominant serotype isolated was Salmonella Typhimurium (S. Typhimurium) in 16(80%) followed by Salmonella enteritidis in 3(15%) and Salmonella C2 in 1(5%) isolates. It was noticed by an increasing trend of resistance to Ampicillin, Chloramphenicol, Cephalosporins (Third generation) and Quinolones over this 18 month study. Based on this study, Conclusions: faecal prevalence of NTS (8.20%) were increasing among motion samples. Majority of isolates were from females (75%) with a mean age group belonging to Adults (46-60yrs). Except for Ampicillin and Cotrimoxazole, NTS isolates exhibited high rates of resistance to rst-line antibiotics. The gradual but consistent increase in resistance to Ampicillin, Fluoroquinolones, third generation Cephalosporins may restrict future treatment 1 options. Hence periodic monitoring of NTS infections, serotype distribution and antimicrobial resistance trend is recommended .

Evaluation of Intervention Measures on Controlling the Dissemination of Nontyphoidal Salmonella Disease in Mukuru Informal Settlement, Nairobi County, Kenya.

Nontyphoidal Salmonella is the most common bacterial pathogen causing gastrointestinal infection worldwide. Data is limited on the effectiveness of the intervention measures put in place to help control the dissemination of nontyphoidal Salmonella disease on Mukuru informal settlement in Nairobi County, Kenya. The aim of the study was to determine the effectiveness of the intervention measures put in place to prevent and control the dissemination of nontyphoidal Salmonella disease in Mukuru informal settlement in Nairobi County, Kenya. A cross-sectional study was conducted in patients aged 0-5 years. Nontyphoidal Salmonella (NTS) bacteria was cultured from blood and stool collected from the recruited children who reported at three health facilities with symptoms of diarrhea, fever or vomiting and antimicrobial susceptibility testing of the recovered NTS isolates from the stool and blood samples was performed. A questionnaire was administered to obtain relevant demographic, socio-economic and healthcare utilization information. Fisher’s test was conducted to determine the difference in the susceptibility patterns between the isolated NTS. Out of 191 collected samples, 3 were found to be positive for Salmonella Typhimurium and Salmonella Enteritidis. Both S. Typhimurium and S. Enteritidis isolates were resistant to gentamycin. Salmonella Typhimurium was found also to be resistant to tetracycline drug. Significant differences existed between some of the drugs susceptibility patterns (p= 0.0048). There are still AMR strains circulating in Mukuru informal settlement. There is still need for the Kenyan government to strengthen knowledge and understanding of AMR through supporting surveillance and research.

Physiological characteristics and virulence gene composition of selected serovars of seafood-borne Salmonella enterica.

All serotypes of Salmonella enterica are considered potentially pathogenic. However, the non-typhoidal Salmonella (NTS) serotypes vary considerably in terms of pathogenicity and the severity of infections. Although diverse serotypes of NTS have been reported from tropical seafood, their sources, physiological characteristics, and virulence potentials are not well understood. This study aimed to compare the physiological characteristics of selected serovars of Salmonella from seafood and investigate possible variations in the distribution of known genes within the pathogenicity islands. A series of biochemical tests, including carbohydrate fermentation and amino acid decarboxylation tests were performed to physiologically compare the isolates. The genetic characterization with respect to putative virulence genes was done by screening for genes associated with Salmonella pathogenicity island (SPI) I-V, as well as the toxin- and prophage-associated genes by polymerase chain reaction. Irrespective of serotypes, all the isolates uniformly harbored the five SPIs screened in this study. However, some virulence genes, such as the avrA, sodC, and gogB were not detected in all Salmonella isolates. The biochemical profiles of Salmonella serotypes were highly conserved except for variations in inositol fermentation and citrate utilization. All the isolates of this study were weak biofilm formers on polystyrene surfaces. The pathogenicity profiles of environmental NTS isolates observed in this study suggest that they possess the virulence machinery necessary to cause human infections and therefore, urgent measures to contain Salmonella contamination of seafood are required to ensure the safety of consumers.

Multicenter Surveillance of Antimicrobial Resistance among Gram-Negative Bacteria Isolated from Bloodstream Infections in Ghana

Antimicrobial resistance (AMR) in Gram-negative bacteria-causing bloodstream infections (BSIs), such as Klebsiella pneumoniae and non-typhoidal Salmonella (NTS), is a major public health concern. Nonetheless, AMR surveillance remains scarce in sub-Saharan Africa, where BSI treatment is largely empirical. The aim of the study was to determine the distribution and AMR patterns of BSI-causing NTS, K. pneumoniae, and other Gram-negative bacteria in Ghana. A cross-sectional study was conducted between April and December 2021 at eleven sentinel health facilities across Ghana as part of a pilot study on the feasibility and implementation of the human sector AMR surveillance harmonized protocol in sub-Saharan Africa. Gram-negative bacteria recovered from blood specimens of febrile patients were identified using MALDI-TOF and evaluated for antimicrobial resistance using the BD Phoenix M50 analyzer and Kirby-Bauer disc diffusion. The Department of Medical Microbiology at the University of Ghana served as the reference laboratory. Out of 334 Gram-negative blood isolates, there were 18 (5.4%) NTS, 85 (25.5%) K. pneumoniae, 88 (26.4%) Escherichia coli, 40 (12.0%) Acinetobacter baumannii, 25 (7.5%) Pseudomonas aeruginosa, and 77 (23.1%) other Gram-negative bacteria. As a composite, the isolates displayed high resistance to the antibiotics tested-amoxicillin (89.3%), tetracycline (76.1%), trimethoprim-sulfamethoxazole (71.5%), and chloramphenicol (59.7%). Resistance to third-generation cephalosporins [ceftriaxone (73.7%), cefotaxime (77.8%), and ceftazidime (56.3%)] and fluoroquinolones [ciprofloxacin (55.3%)] was also high; 88% of the isolates were multidrug resistant, and the rate of extended-spectrum beta-lactamase (ESBL) production was 44.6%. Antibiotic resistance in K. pneumoniae followed the pattern of all Gram-negative isolates. Antibiotic resistance was lower in NTS blood isolates, ranging between 16.7-38.9% resistance to the tested antibiotics. Resistance rates of 38.9%, 22.2%, and 27.8% were found for cefotaxime, ceftriaxone, and ceftazidime, respectively, and 27.8% and 23.8% for ciprofloxacin and azithromycin, respectively, which are used in the treatment of invasive NTS. The prevalence of multidrug resistance in NTS isolates was 38.9%. Multicenter AMR surveillance of Gram-negative blood isolates from febrile patients was well-received in Ghana, and the implementation of a harmonized protocol was feasible. High resistance and multidrug resistance to first- or second-choice antibiotics, including penicillins, third-generation cephalosporins, and fluoroquinolones, were found, implying that these antibiotics might have limited effectiveness in BSI treatment in the country. Continuation of AMR surveillance in Gram-negative blood isolates is essential for a better understanding of the extent of AMR in these pathogens and to guide clinical practice and policymaking.

Antimicrobial Resistance and Mechanisms of Azithromycin Resistance in Nontyphoidal Salmonella Isolates in Taiwan, 2017 to 2018.

Antimicrobial resistance was investigated in 2,341 nontyphoidal Salmonella (NTS) isolates recovered from humans in Taiwan from 2017 to 2018 using antimicrobial susceptibility testing. Azithromycin resistance determinants were detected in 175 selected isolates using PCR and confirmed in 81 selected isolates using whole-genome sequencing. Multidrug resistance was found in 47.3% of total isolates and 96.2% of Salmonella enterica serovar Anatum and 81.7% of S. enterica serovar Typhimurium isolates. Resistance to the conventional first-line drugs (ampicillin, chloramphenicol, and cotrimoxazole), cefotaxime and ceftazidime, and ciprofloxacin was found in 32.5 to 49.0%, 20.3 to 20.4%, and 3.2% of isolates, respectively. A total of 76 (3.1%) isolates were resistant to azithromycin, which was associated with mph(A), erm(42), erm(B), and possibly the enhanced expression of efflux pump(s) due to ramAp or defective ramR. mph(A) was found in 53% of the 76 azithromycin-resistant isolates from 11 serovars and located in an IS26-mph(A)-mrx(A)-mphR(A)-IS6100 unit in various incompatibility plasmids and the chromosomes. erm(42) in S. enterica serovar Albany was carried by an integrative and conjugative element, ICE_erm42, and in S. enterica serovar Enteritidis and S. Typhimurium was located in IS26 composite transposons in the chromosomes. erm(B) was carried by IncI1-I(α) plasmids in S. Enteritidis and S. Typhimurium. ramAp was a plasmid-borne ramA, a regulatory activator of efflux pump(s), found in only S. enterica serovar Goldcoast. Since the azithromycin resistance determinants are primarily carried on mobile genetic elements, they could easily be disseminated among human bacterial pathogens. The ramAp-carrying S. Goldcoast isolates displayed azithromycin MICs of 16 to 32 mg/L. Thus, the epidemiological cutoff value of ≤16 mg/L of azithromycin proposed for wild-type NTS should be reconsidered. IMPORTANCE Antimicrobial resistance in NTS isolates is a major public health concern in Taiwan, and the mechanisms of azithromycin resistance are rarely investigated. Azithromycin and carbapenems are the last resort for the treatment of invasive salmonellosis caused by multidrug-resistant (MDR) and extensively drug-resistant Salmonella strains. Our study reports the epidemiological trend of resistance in NTS in Taiwan and the genetic determinants involved in azithromycin resistance. We point out that nearly half of NTS isolates from 2017 to 2018 are MDR, and 20% are resistant to third-generation cephalosporins. The azithromycin resistance rate (3.1%) for the NTS isolates from Taiwan is much higher than those for the NTS isolates from the United States and Europe. Our study also indicates that azithromycin resistance is primarily mediated by mph(A), erm(42), erm(B), and ramAp, which are frequently carried on mobile genetic elements. Thus, the azithromycin resistance determinants could be expected to be disseminated among diverse bacterial pathogens.

Antimicrobial Resistance in Non-typhoidal Salmonella from Retail Foods Collected in 2020 in China

Objective: Non-typhoidal Salmonella (NTS) is a major cause of human salmonellosis globally. Food animals are major NTS reservoirs. An increase in antimicrobial resistance (AMR) in foodborne NTS has led to clinical treatment failures. Here, to examine the prevalence and perform characterization of foodborne NTS with AMR in China, we tested the antimicrobial susceptibility of 1,256 NTS isolates cultured from retail foods in 2020 in China. Methods: The antimicrobial susceptibility of 26 antimicrobial agents representing 12 classes was evaluated with the broth-microdilution method; the presence of ten mcr genes was screened with multi-PCR. The complete closed genomes of mcr-gene-carrying isolates were generated by hybrid assembly through whole genome sequencing on both the PacBio and Illumina platforms. Genomic features and genetic environments of the mcr-1 gene were analysed. Results: The overall drug resistance rate was 92.28%, and the multi-drug resistance (MDR) rate was 76.53%. A total of 341 AMR profiles were determined, and resistance was highest to nalidixic acid (63.38%). Among 887 NTS isolates with MDR, 232 showed co-resistance to cefotaxime and ciprofloxacin, and 25 were resistant to ten classes of antimicrobial agents. The resistance of NTS isolated from different regions varied. Isolates from raw chicken sources most frequently showed resistance. Four NTS carried the mcr-1 gene and represented four different serotypes. Four mcr-1 gene-bearing plasmids from the four Salmonella isolates were classified into two replicon types (IncI2 and IncHI2A). Two mcr-1 genes in IncI2 type plasmids were found to be located between a PAP2 family protein-encoding gene and a relaxase-encoding gene, whereas the other two mcr-1 gene structures in IncHI2A type plasmids showed variations in the presence of insertion sequences. Conclusion: Our data demonstrated severe AMR among foodborne NTS isolated from food in China, thus highlighting the importance of antimicrobial susceptibility surveillance to decrease the spread of AMR, particularly to critical drugs in human medicine.

1367. Resistance to Ceftriaxone and Ciprofloxacin in Nontyphoidal Salmonella from Humans and Relatedness to Isolates from Animal Sources

Abstract Background Nontyphoidal Salmonella (NTS) is a leading cause of foodborne bacterial infections. Annually, ∼200,000 antimicrobial-resistant (AMR) NTS illnesses occur in the United States. NTS infections resistant to ceftriaxone and ciprofloxacin, drugs used for the treatment of severe infections, are a growing concern. Methods We identified patient NTS isolates submitted to the Pennsylvania Bureau of Laboratories by two hospitals from the same health system during 2018–2020. All were tested by broth microdilution for susceptibility to antibiotics tracked by the National Antimicrobial Resistance Monitoring System and analyzed by whole-genome sequencing. We identified resistance mechanisms and plasmids with ResFinder and PlasmidFinder, respectively, and compared each isolate in selected serotypes against the PulseNet database to identify genetic relatedness within ≤5 allele differences to non-human sequences uploaded during 2017–2021. Results Of 164 human NTS analyzed for susceptibility, 28 (17%) had decreased susceptibility to ciprofloxacin (DSC) [MIC ≥0.12 µg/mL] while 6 (3.7%) were ceftriaxone-resistant. AMR varied by serotype; 8 (50%) S. Infantis and 16 (42%) Enteritidis had DSC, representing 86% of all isolates with DSC (Figure). Six ceftriaxone-resistant isolates had genes that confer resistance to third-generation cephalosporins including blaCMY−2 in 1 Dublin and 2 Typhimurium and blaCTX-M-65 in 3 Infantis isolates. The 3 Infantis isolates also had a mutation in gyrA that results in DSC, plus a known transmissible plasmid IncFIB(pN55391) linked to multiple resistance genes. An Infantis isolate was related to a chicken meat isolate and a Hadar isolate was related to isolates from 3 animals and 3 meat sources. One Dublin isolate was related to 2 isolates from beef in Pennsylvania. Figure.Percent of antimicrobial resistance in nontyphoidal Salmonella (NTS) clinical isolates (n=164) submitted to public health authorities by two hospital systems in Pennsylvania, 2018–2020. Multidrug resistance (MDR) was defined as resistance to ≥3 of the 9 antimicrobial classes tested for NTS clinical isolates. Resistance to ceftriaxone (AXO), a third-generation cephalosporin preferred for treating severe infections in children, was over 5% and 19% in serotypes S. Typhimurium and S. Infantis, respectively. Half (8/16) of Infantis isolates and 42% (16/38) of Enteritidis isolates had decreased susceptibility to ciprofloxacin (DSC). Conclusion Ceftriaxone resistance and DSC in NTS from patients in Pennsylvania varied by serotype and some isolates harbored blaCMY−2 and blaCTX-M-65 genes. Dissemination of mechanisms that confer resistance to ceftriaxone and DSC is concerning as is the genetic relatedness of isolates from human and animal sources. Our study highlights the need for enhanced One Health AMR monitoring combined with a review of animal production and food processing practices. Disclosures All Authors: No reported disclosures.

Antibacterial potency of Vernonia amygdalina on antibiotic-resistant non-typhoidal salmonella isolates from human and animal sources in southern Taraba, North-East, Nigeria

Antibiotic discovery was considered a wonder of the world. Shortly after, many microorganisms began to exhibit resistance to prior antimicrobial actions of antibiotics. Notwithstanding, Quinones, Flavonoids, Flavones, Flavonols, Tannins, and Coumarins are major phytochemicals synthesized by plant parts and have shown decisive antimicrobial activities against a panel of microorganisms. In this research hot and cold extracts of fresh and dried Vernonia, amygdalina showed remarkable in vivo antimicrobial activity on antibiotic-resistant Salmonella isolates from various poultry farms and food vendors in Ibi, Donga, Takum, and Wukari. 5 g-10 ml, 10 g-10 ml, 15g-10ml, 20g-10ml, and 25g-10ml are arrays of Vernonia Amygdalina concentrations tested on the inocula. Significant light growth was observed for both menstruum extracts of dried and fresh leaves of Vernonia Amygdalina at higher concentrations levels of 20g-10ml, 25g-10ml, while and moderate growth was seen at lower concentrations levels of 5g-10ml, 10g-10ml. Also, heavy growth of Salmonella was detected in the control plates inoculated with the test microorganism but without the addition of any extracts. Weak political will in implementing regulation policies, funding of research, and perceived antimicrobial resistance to plant extracts as well as acceptability and cultural factors have threatened the extensive use of plant extract in the management of health. Improved universal health coverage and enhanced economic potentials are core benefits of the use of plant extracts for health management. Conclusively, plant extracts possess appreciable antimicrobial activities against Multi-Drug Resistance (MDR) microorganisms compared to currently prescribe synthetic drugs. Hence, further studies on clinical efficacy trials and the safety of more plants need to be intensified.

The Clinical Implication of Serogroup Distribution and Drug Resistance of Non-Typhoidal Salmonella in Children: A Single Center Study in Southern Taiwan during 2004-2019.

Background: A regional antibiotic susceptibility database of certain pathogens is crucial for first-line physicians in terms of providing clinical judgement and appropriate selection of antimicrobial agents. The aim of this study is to update the epidemiological data of Salmonella serogroups and drug resistance in pediatric patients. Methods: This is a single-center retrospective study enrolling patients aged from 0 to 18 years who were hospitalized with cultured proven non-typhoidal Salmonella (NTS) infection from 2004 to 2019. The isolates were collected and the demographic data, serogroups of Salmonella and antimicrobial susceptibilities were further analyzed. Results: A total of 1583 isolates of NTS were collected. Serogroup C2 was prone to cause invasive non-typhoidal salmonellosis (iNTS), especially bacteremia. Patients aged < 2 years were associated with serogroups B and C2 infection, while those aged ≥ 2 years were associated with serogroups D and E infection. The prevalence of serogroup B declined with simultaneous increase in prevalence of serogroups D and E. Serogroups B and E were associated with ceftriaxone resistance, while Serogroup D was less drug-resistant than the others. The prevalence of ceftriaxone-resistant Salmonella had not increased, although more ciprofloxacin-resistant isolates were found in iNTS infection. Conclusions: Age < 2 years is a risk factor of iNTS for children, and the distribution of serogroup changes should be closely monitored. Ceftriaxone is still the drug of choice for treating pediatric iNTS infection, and although no increase was observed in the prevalence of ceftriaxone-resistant strains in this study, continuing surveillance of such cases is warranted.

Using genetic markers for detection and subtyping of the emerging Salmonella enterica subspecies enterica serotype Muenchen

Non-typhoidal Salmonella (NTS) poses a global threat to public health. Poultry, one of the main reservoirs of NTS, is usually not clinically affected by most NTS, yet the economic losses to the poultry industry due to control and mitigation efforts, and due to negative publicity can be tremendous.NTS strains are routinely characterized into serotypes in a time-consuming, labor-intensive multistep process that requires skilled personnel. Moreover, the discriminatory power of serotyping is limited compared to other subtyping methods. Whole-genome sequence data enable the identification of genetic variation within serotypes. However, sequencing is often limited by available resources, and analyzing and interpreting the genetic data may be time-consuming. Source tracing during epidemiological outbreak investigations requires rapid and efficient characterization of strains to control pathogen spread. Here we designed a multiplex polymerase chain reaction (PCR) assay for the detection of genetic variants of Salmonella Muenchen, a serotype that has emerged in Israel in the last 3 yr in both clinical human cases and different hosts. Test sensitivity of 99.21% and specificity of 94 to 100% were determined using in-silico PCR with a dataset of 18,282 NTS assemblies from 37 NTS serotypes. Similarly, test sensitivity of 100% and specificity of 96.2 to 100% were determined in-vitro with 120 NTS isolates of 52 serotypes. Moreover, the test enabled differentiation between the common sequence types of serotype Muenchen using both approaches. As opposed to traditional serotyping and other subtyping methods, the designed test allows for rapid and cost-efficient detection of the emerging S. Muenchen serotype and its variants in a single step. Future development of similar assays for other dominant serotypes may help reduce the time and cost required for detection and initial characterization of dominant NTS strains. Overall, these tests will be beneficial to both public health and for reducing of the economic losses to the poultry industry due to NTS infections.

Clinical profiles and antimicrobial resistance patterns of invasive Salmonella infections in children in China

Invasive Salmonella infections result in a significant burden of disease including morbidity, mortality, and financial cost in many countries. Besides typhoid fever, the clinical impact of non-typhoid Salmonella infections is increasingly recognized with the improvement of laboratory detection capacity and techniques. A retrospective multicenter study was conducted to analyze the clinical profiles and antimicrobial resistance patterns of invasive Salmonella infections in hospitalized children in China during 2016–2018. A total of 130 children with invasive Salmonella infections were included with the median age of 12 months (range: 1–144 months). Seventy-nine percent of cases occurred between May and October. Pneumonia was the most common comorbidity in 33 (25.4%) patients. Meningitis and septic arthritis caused by nontyphoidal Salmonella (NTS) infections occurred in 12 (9.2%) patients and 5 (3.8%) patients. Patients < 12 months (OR: 16.04) and with septic shock (OR: 23.4), vomit (OR: 13.33), convulsion (OR: 15.86), C-reactive protein (CRP) ≥ 40 g/L (OR: 5.56), and a higher level of procalcitonin (PCT) (OR: 1.05) on admission were statistically associated to an increased risk of developing meningitis. Compared to 114 patients with NTS infections, 16 patients with typhoid fever presented with higher levels of CRP and PCT (P < 0.05). The rates of resistance to ampicillin, sulfamethoxazole/trimethoprim, ciprofloxacin, and ceftriaxone among Salmonella Typhi and NTS isolates were 50% vs 57.3%, 9.1% vs 24.8%, 0% vs 11.2%, and 0% vs 9.9%, respectively. NTS has been the major cause of invasive Salmonella infections in Chinese children and can result in severe diseases. Antimicrobial resistance among NTS was more common.