Comparative Whole-Genome Analysis of Russian Foodborne Multidrug-Resistant Salmonella Infantis Isolates

Non-typhoidal Salmonella infections remain a significant public health problem worldwide. In this study, we present the first detailed genomic analysis report based on short-read (Illumina) whole-genome sequencing (WGS) of 45 multidrug-resistant (MDR) Salmonella enterica subsp. enterica serotype Infantis isolates from poultry and meat product samples obtained in Russia during 2018–2020, and long-read (MinION) WGS of five more representative isolates. We sought to determine whether foodborne S. Infantis have acquired new characteristics, traits, and dynamics in MDR growth in recent years. All sequenced isolates belonged to the sequence type ST32 and more than the half of isolates was characterized by six similar antimicrobial susceptibility profiles, most of which corresponded well with the antimicrobial resistance determinants to aminoglycosides, sulphonamides, tetracycline, and chloramphenicol revealed in silico. Some of the isolates were characterized by the presence of several types of plasmids simultaneously. Plasmid typing using WGS revealed Col440I, ColpVC, ColRNAI, IncFIB, IncFII, IncX1, IncHI2, IncHI2A, and IncN replicons. The identified virulence genes for 45 whole genomes of S. Infantis were similar and included 129 genes encoding structural components of the cell, factors responsible for successful invasion of the host, and secreted products. These data will be a valuable contribution to further comparative genomics of S. Infantis circulating in Russia, as well as to epidemiological surveillance of foodborne Salmonella isolates and investigations of Salmonella outbreaks.

Prevalence and antibiotic resistance of Salmonella isolated from poultry and its environment in the Mekong Delta, Vietnam

Background and Aim: Salmonella is one of the leading causes of zoonotic and foodborne infectious outbreaks in humans and poultry and its associated environment is a potential reservoir of Salmonella. In recent years, the antibiotic resistance of bacteria, including Salmonella, has been increasing. This study aimed to investigate the prevalence and antibiotic resistance of Salmonella isolated from poultry, its environment, and the pest animals found at poultry farms and households of the Mekong Delta, Vietnam. Materials and Methods: A total of 3,055 samples were collected from the broiler farms and households of the Mekong Delta from 2017 to 2020. Salmonella was isolated using conventional methods (culturing on selective agar – BPLS and biochemical test) and the isolates were examined for antibiotic resistance against 14 antibiotics using the disk diffusion method. Results: Salmonella was isolated from 181 samples (5.92%), which included chicken feces (7.67%), pest animals (5.98%), and environmental samples (4.33%). The environmental samples comprised bedding (5.88%), feed (5.48%), and drinking water (0.70%). The prevalence of Salmonella was the highest in rats (15.63%) and geckos (12.25%) followed by ants (2.83%) and cockroaches (2.44%); however, Salmonella was not isolated from any fly species. Most of the isolates exhibited resistance to 1-9 antibiotics. The isolates were relatively resistant to chloramphenicol (62.98%), tetracycline (55.80%), ampicillin (54.14%), and sulfamethoxazole/trimethoprim (53.04%). Sixty-two multiple resistance patterns were found in the isolates, with ampicillin-cefuroxime-chloramphenicol-tetracycline- sulfamethoxazole/trimethoprim being the most frequent (7.18%). Conclusion: The chickens, husbandry environment, and pest animals at poultry farms and households were found to be important Salmonella sources in the Mekong Delta. Salmonella isolates from these sources also exhibited a wide-ranging resistance to antibiotics as well as several resistance patterns. Hence, biosecurity should be addressed in poultry farms and households to prevent cross-contamination and reduce the spread of Salmonella infections.

Retrospective analysis of the emergence of antibiotic-resistant Salmonella enterica infections in a level IV hospital from Lima, Peru

This study retrospectively analysed the emergence of multidrug-resistant Salmonella enterica in a level IV hospital in Lima, Peru. A total of 64 S. enterica from January 2009 to June 2010 (Period 1, 24 isolates) and January 2012 to December 2014 (Period 2, 40 isolates) were included. Some 25 were from non-hospitalized and 39 from hospitalized patients. Antimicrobial susceptibility to 15 antimicrobial agents was established by automated methods. Most of the isolates were from blood (46.9%), urine (21.9%) and faeces (14.1%). There was a reduction in blood isolates in Period 2, while all the faecal isolates were from this period. In Period 1, only 3/24 (12.5%) isolates showed antibiotic resistance, whereas 25/39 isolates (64.1%) from Period 2 were antibiotic-resistant, with multidrug-resistant and extensively drug-resistant rates of 17.9% and 20.5%, respectively. Multidrug-resistant/extensively drug-resistant Salmonella isolates were introduced in the hospital in 2013, with Salmonella recovered from faeces from non-hospitalized patients suggested an increase in community-acquired multidrug-resistant/extensively drug-resistant Salmonella infections.

Alternative and Complementary Therapies against Foodborne Salmonella Infections

The limitations in the therapeutic options for foodborne pathogens lead to treatments failure, especially for multidrug-resistant (MDR) Salmonella sp., worldwide. Therefore, we aimed to find alternative and complementary therapies against these resistant foodborne pathogens. Out of 100 meat products samples, the prevalence rate of salmonella was 6%, serotyped only as S. Typhimurium and S. Enteritidis. According to the antibiotic susceptibility assays, the majority of our isolates were MDR and susceptible to cefotaxime. Out of the 13 tested plant extracts, five only showed an inhibition zone in the range of 8–50 mm against both serotypes. Based on their promising activity, the oily extract of cinnamon and aqueous extract of paprika represented the highest potency. Surprisingly, a significant synergistic effect was detected between cinnamon oil and cefotaxime. Depending on Gas Chromatography/Mass Spectrometry (GC-MS), the antimicrobial activity of cinnamon oil was attributed to four components including linalool, camphor, (Z)-3-Phenylacrylaldehyde and its stereoisomer 2-Propenal-3-phenyl. The anti-virulence activities of these compounds were confirmed on the basis of computational molecular docking studies. Accordingly, we recommended the use of cinnamon oil as a food additive to fight the resistant foodborne pathogens. Additionally, we confirmed its therapeutic uses, especially when co-administrated with other antimicrobial agents.

The Interplay between Salmonella and Intestinal Innate Immune Cells in Chickens

Salmonellosis is a common infection in poultry, which results in huge economic losses in the poultry industry. At the same time, Salmonella infections are a threat to public health, since contaminated poultry products can lead to zoonotic infections. Antibiotics as feed additives have proven to be an effective prophylactic option to control Salmonella infections, but due to resistance issues in humans and animals, the use of antimicrobials in food animals has been banned in Europe. Hence, there is an urgent need to look for alternative strategies that can protect poultry against Salmonella infections. One such alternative could be to strengthen the innate immune system in young chickens in order to prevent early life infections. This can be achieved by administration of immune modulating molecules that target innate immune cells, for example via feed, or by in-ovo applications. We aimed to review the innate immune system in the chicken intestine; the main site of Salmonella entrance, and its responsiveness to Salmonella infection. Identifying the most important players in the innate immune response in the intestine is a first step in designing targeted approaches for immune modulation.

Twenty-four month longitudinal study suggests little to no horizontal gene transfer in situ between third-generation cephalosporin-resistant Salmonella and third-generation cephalosporin-resistant Escherichia coli in a beef cattle feedyard

Third-generation cephalosporins (3GCs) are preferred treatments for serious human Salmonella enterica infections. Beef cattle are suspected to contribute to human 3GC-resistant Salmonella infections. Commensal 3GC-resistant Escherichia coli are thought to act as reservoirs of 3GC resistance since they are more frequently isolated than 3GC-resistant Salmonella at beef cattle feedyards. During each of 24 consecutive months 4 samples of pen surface material were obtained from 5 pens ( N = 480) at a Nebraska feedyard to determine to the contribution of 3GC-resistant E. coli to the occurrence of 3GC-resistant Salmonella . Illumina whole genome sequencing was performed and susceptibilities to 14 antimicrobial agents were determined for 121 3GC-susceptible Salmonella , 121 3GC-resistant Salmonella , and 203 3GC-resistant E. coli isolates. 3GC-susceptible Salmonella isolates were predominantly Muenchen (70.2%) and Montevideo Clade 1 (23.1%). 3GC-resistant Salmonella isolates were predominantly Montevideo Clade 2 (84.3%). One bla gene type ( bla CMY-2 ) and the IncC plasmid replicon were present in 100% and 97.5% of the 3GC-resistant Salmonella , respectively. Eleven bla gene types were detected in the 3GC-resistant E. coli . The 3GC-resistant E. coli were distributed across 42 multilocus sequence types. The bla CMY-2 gene and IncC plasmid replicon were present in 37.9% and 9.9% of the 3GC-resistant E . coli , respectively. These results suggested that 3GC resistance in Salmonella was primarily due the persistence of Montevideo Clade 2 with very minimal or no contribution from 3GC-resistant E. coli via horizontal gene transfer, suggesting that 3GC-resistant E. coli may not be a useful indicator for 3GC-resistant Salmonella in beef cattle production environments.

Isolation and Study of Bacteriophages Specific Against Multidrug Resistant Salmonella spp. and Assessment of their Therapeutic Potential

Within the scope of the study, clinical non-typhoidal Salmonella were isolated in Armenia and Georgia and identified based on conventional microbiological methods and MALDI-TOF MS. These isolates were further analysed by serotyping (White-Kauffmann-Le Minor scheme) and their antimicrobial susceptibility profiles were defined. A total of 40 antibiotic resistance profiles were identified, of which 35 were characteristic of clinical strains. Out of a total of 345 isolates, 238 strains from Georgia, Armenia and Ireland were eventually selected for our study.Using the strains of this collection, 13 new bacteriophages were isolated, characterized by biological and genetic features. Based on the data obtained, phages were classified and the peculiarities of their life cycle were determined (virulent-lytic, moderate-lysogenic).Analysis of the sequencing results showed that only one of the 12 phages identified as temperate phage (vB_GEC_ TR), it belongs to the family Podoviridae, genus-Laderbergvirus. While the other 11 phages are virulent, they are related to well-known and characterized phages, which are used in various phage preparations. Analysis of their genomes did not show any lysogeny associated genes. Among the virulent phages, 6 are members of Myoviridae family (vB_GEC_B1, vB_GEC_B3, vB_GEC_MG, vB_GEC_BS, vB_GEC_NS7, vB_GEC_7A) and 5 of the Syphoviridae family (vB_GEC_N5, vB_GEC_N8, vB_GEC_M4, vB_GEC_M5, vB_GEC_Hi). In vitro tests revealed that the phages - vB_GEC_B1, vB_GEC_BS, vB_GEC_B3, vB_GEC_NS7, vB-GEC-N8 showed high activity (60% to 80%) against the examined strains. The phages have been shown to be more effective against clinical strains (≈90%) than against veterinary strains (≈70%). The strains susceptible to these phages were mainly S.typhimurium and S. Enteritidis serovars and are largely of clinical origin. Based on our research we can conclude that the application of phages as an additional tool for the treatment of MDR Salmonella infections seems to be plausible. Phages are natural and specific antibacterial agents, which can lyse bacteria.irrespective of their AMR status, whilst leaving the commensal microflora unharmed. This is one of the main advantages of phages in comparison to antibiotics. The phages tested in this study showed potential for application in phage therapy against MDR Salmonella infections.

Epidemiological Investigation of Salmonella enterica Isolates in Children with Diarrhea in Chengdu, China

Background: Children with the immature intestinal immune system are prone to Salmonella infection through the fecal-oral route causing diarrhea. Non-typhoid Salmonella (NTS) is difficult to treat and eliminate due to its zoonosis. Salmonella typhi, including typhoid and paratyphoidA, B, and C, only infect humans and cause invasive infectious diseases. Salmonella typhi infection is serious and requires antibiotic treatment. The bacterial resistance caused by conventional antibacterial drugs brings great difficulties to treatment. Objectives: This study aimed to investigate the epidemiology of S. enterica in children with diarrhea in Chengdu, China. Methods: Fresh stool specimens or rectal swabs from 6656 children aged 1 day to 17 years with diarrhea were collected, cultured, identified, and tested for antimicrobial susceptibility. Analytical Profile index 20E was used for biochemical identification, and the Kirby-Bauer method was used for the bacterial sensitivity test. The whole process was conducted in accordance with the fourth edition of the National Clinical Examination procedures, and the drug sensitivity test was conducted in accordance with the Clinical and Laboratory Standards Institute 2020 guidelines. Results: A total of 649 Salmonella strains were isolated from 6656 children with suspected Salmonella infection, among which the isolation rates of NTS and S. typhi were 8.92% and 0.83%, respectively. The infection rate of S. typhimurium was the highest every year (74.88%). Salmonella infections are on the rise, especially typhimurium, Dublin, Typhi, and London. Paratyphi is unstable, presenting a phenomenon of transition and replacement (the male to female ratio:1.12:1). The infection rate was the lowest within 1 day and 6 months (P < 0.05). Salmonella mainly infected children under 3 years of age, and the positive rate was reported as 88.29%. Within June-September, the infection rate of Salmonella was the highest, with a positive rate of 72.73%. The isolated 649 Salmonella strains had good susceptibility to cefotaxime and ciprofloxacin (87.7% and 79.2%, respectively), almost no susceptibility to ampicillin, and a drug resistance rate of 92.9%. Conclusions: typhoid and paratyphoid vaccines should be considered together, and vaccines should focus on children under 3 years of age. Antibiotics should be rationally selected according to the drug sensitivity test and disease condition.

1258. Antibiotic Resistant Nontyphoidal Salmonella Infection Following International Travel — United States, 2018

Background Antibiotic resistance in nontyphoidal Salmonella can limit treatment options for patients requiring antibiotic therapy. We assessed the contribution of international travel to resistance among nontyphoidal Salmonella infections. Methods We describe characteristics of nontyphoidal Salmonella infections in the Foodborne Diseases Active Surveillance Network during 2018 that were also reported to PulseNet and the National Antimicrobial Resistance Monitoring System. We defined genetic resistance to first-line antibiotics as the presence of genes or mutations known to confer decreased susceptibility or resistance to ciprofloxacin, azithromycin, or ceftriaxone. We used multivariable logistic regression to assess the association between resistance to first-line antibiotics and international travel in the 7 days before symptom onset overall and by United Nations statistical region, and we estimated the contribution of travel to resistance using population attributable fractions. Results Among 3,238 nontyphoidal Salmonella infections, 356 (11%) were in patients who traveled internationally in the 7 days before symptom onset. Of these, 109/356 (31%) had isolates with genetic resistance to first-line antibiotics, compared with 308/2882 (11%) non-travelers. Resistance was more likely following travel, after adjusting for age and sex (OR 3.7, 95% CI 2.9–4.8). Nine genes or mutations conferred resistance to first-line antibiotics among travel-associated isolates. The risk of resistance varied by region and was highest after travel to Asia (OR 7.5, 95% CI 4.7–12.0). Overall, 17.1% (95% CI 12.2%–21.7%) of genetic resistance to first-line antibiotics was attributable to international travel. Conclusion For patients with nontyphoidal Salmonella infections, international travel is associated with approximately three-fold increased risk that first-line agents could be ineffective. The estimated 17% of resistance to first-line antibiotics attributable to travel is encoded by relatively few genes and mutations. Investigation of the major sources of resistant strains could help target prevention efforts. Travel region should be considered when treating empirically; treatment should be adjusted based on results from antibiotic susceptibility testing. Disclosures All Authors: No reported disclosures