Infantis Strains Research Articles

Nationwide surveillance and characterization of the third-generation cephalosporin-resistant Salmonella enterica serovar infantis isolated from chickens in South Korea between 2010 and 2022

The occurrence of extended-spectrum β-lactamase (ESBL)/AmpC β-lactamase-producing Salmonella conferring resistance to third-generation cephalosporin has emerged as a global public health concern. In this study, we aimed to investigate the prevalence and molecular characterization of third-generation cephalosporin-resistant Salmonella enterica serovar Infantis. In total, 409 S. Infatis isolates were collected from the feces and carcasses of healthy and diseased food animals, including chickens (n = 348), pigs (n = 48), cattle (n = 8), and ducks (n = 5) between 2010 and 2022 nationwide in South Korea. Among them, 61.9 % (253/409) of S. Infantis strains displayed resistance to ceftiofur, with the most resistant isolates obtained from chickens (98.4 %, 249/253). Moreover, S. Infantis isolates showed high resistance (47.7–67.2 %) to streptomycin, ampicillin, nalidixic acid, sulfisoxazole, chloramphenicol, tetracycline, and trimethoprim/sulfamethoxazole. Additionally, the multidrug resistance (MDR) was significantly greater in the ceftiofur-resistant isolates compared to the ceftiofur-susceptible isolates (p < 0.05). All the ceftiofur-resistant S. Infantis strains produced CTX-M/CMY-2 β-lactamase enzymes, with blaCTX-M-65 comprising the most (98.4 %, 249/253), followed by blaCTX-M-15 (1.2 %, 3/253), and blaCMY-2 (0.4 %, 1/253). The ceftiofur-resistant S. Infantis belonged to 37 different pulsotypes, with X1A1 (26.1 %, 66/253), X1A2 (20.9 %, 53/253), and X5A3 (9.1 %) being the most prevalent, representing a total of 56.1 % (142/253). Furthermore, the S. Infantis sequence type (ST)32 was the most common, accounting for 91.9 % (34/37) of the three distinct STs (ST32, ST16, and ST11) detected across farms located in various provinces nationwide. Most of the blaCMX-M-65 genes (77.5 %, 193/249), all of the blaCTX-M-15 genes (100 %, 3/3), and the blaCMY-2 gene (100 %, 1/1) were transferred to the recipient E. coli RG488 by conjugation. In addition, the majority of the transconjugants (98.9 %, 191/193) containing blaCTX-M-65 genes belong to the IncFIB replicon type, playing an important role in the quick and widespread dissemination of S. Infantis. Thus, ceftiofur-resistant S. Infantis carrying the β-lactamase genes in chickens has the potential to be transmitted to humans.

Emergence and Comparative Genome Analysis of Salmonella Ohio Strains from Brown Rats, Poultry, and Swine in Hungary.

Rats are particularly important from an epidemiological point of view, because they are regarded as reservoirs for diverse zoonotic pathogens including enteric bacteria. This study is the first to report the emergence of Salmonella serovar Ohio in brown rats (Rattus norvegicus) and food-producing animals in Hungary. We first reveal the genomic diversity of the strains and their phylogenomic relationships in the context of the international collection of S. Ohio genomes. This pathogen was detected in 4.3% (4/92) of rats, captured from multiple sites in Hungary. A whole-genome-based genotype comparison of S. Ohio, Infantis, Enteritidis, and Typhimurium strains showed that 76.4% (117/153) of the virulence and antimicrobial resistance genes were conserved among these serovars, and none of the genes were specific to S. Ohio. All S. Ohio strains lacked virulence and resistance plasmids. The cgMLST phylogenomic comparison highlighted a close genetic relationship between rat and poultry strains of S. Ohio from Hungary. These strains clustered together with the international S. Ohio genomes from aquatic environments. Overall, this study contributes to our understanding of the epidemiology of Salmonella spp. in brown rats and highlights the importance of monitoring to minimize the public health risk of rodent populations. However, further research is needed to understand the route of infection and evolution of this serovar.

Genetic characterization of blaCTX-M-65 in Salmonella Infantis and blaCMY-2 in Salmonella Heidelberg isolated from fresh ground turkey meat sold in supermarkets in Los Andes and San Felipe, Chile

Annually, food poisoning caused by non-typhoidal Salmonella (NTS) accounts for 40 million foodborne infections worldwide. Outbreaks due to multidrug-resistant NTS strains are associated with the consumption of poultry products. We aimed to determine the proportion of NTS in ground turkey meat available at supermarkets in two locations in Chile, characterizing their serovars, virulence traits, and antimicrobial resistance profiles. Between September and December 2018, we analyzed 47 samples of packed ground turkey meat purchased at 13 supermarkets. NTS were identified by MALDI-TOF, and antimicrobial susceptibility was determined by the disk-diffusion agar method. Whole genome sequencing was performed with MiSeq (Illumina) followed by Nullarbor analysis. NTS was detected in 6 out of 47 samples (12.8 %, 95 %CI: 6.0–25.1 %), identifying S. enterica serovar Infantis (n=4 isolates), serovar Agona (n=1 isolate), and serovar Heidelberg (n=1 isolate), respectively. S. Infantis belonged to sequence type (ST)32, differentiating two clones, whereas the S. Agona was ST13 and S. Heidelberg was ST15. S. Infantis strains were multidrug antibiotic resistant, harboring blaCTX-M-65, tetA, and mutations that confer fosfomycin resistance. Serovars Agona and Heidelberg showed tetracycline (tetB) and fosfomycin resistance (fosA7). Additionally, serovar Heidelberg showed resistance to sulfamethoxazole-trimethoprim, aminoglycosides, and carried the blaCMY-2 gene. This is the first report in Chile about NTS detected in raw ground turkey meat available in supermarkets. S. Infantis and S. Agona strains showed a phylogenetic relationship with strains of the same serovars isolated from the environment in our country. This situation would impact food poisoning and the dissemination of bacterial resistance between animals, humans, and the environment.

High Biofilm-Forming Multidrug-Resistant Salmonella Infantis Strains from the Poultry Production Chain.

The ability of Salmonella species to adhere to surfaces and form biofilms, leading to persistent environmental reservoirs, might represent a direct link between environmental contamination and food processing contamination. The purpose of this study was to investigate the biofilm-forming ability of 80 multidrug-resistant (MDR) and extended-spectrum beta-lactamase (ESBL) producing Salmonella enterica serovar Infantis strains isolated from the broiler food chain production through whole genome sequencing (WGS), PCR, and morphotype association assays. Biofilm formation was quantified by testing the strains at two different temperatures, using 96-well polystyrene plates. The rough and dry colony (rdar) morphotype was assessed visually on Congo red agar (CRA) plates. Based on our results, all tested S. Infantis strains produced biofilm at 22 °C with an rdar morphotype, while at 37 °C, all the isolates tested negative, except one positive. Most isolates (58.75%) exhibited strong biofilm production, while 36.25% showed moderate production. Only 5 out of 80 (6.25%) were weak biofilm producers. WGS analysis showed the presence of the fim cluster (fimADF) and the csg cluster (csgBAC and csgDEFG), also described in S. Typhimurium, which are responsible for fimbriae production. PCR demonstrated the presence of csgD, csgB, and fimA in all 80 S. Infantis strains. To our knowledge, this is the first study comparing the effects of two different temperatures on the biofilm formation capacity of ESBL producing S. Infantis from the broiler production chain. This study highlights that the initial biofilm components, such as curli and cellulose, are specifically expressed at lower temperatures. It is important to emphasize that within the broiler farm, the environmental temperature ranges between 18-22 °C, which is the optimum temperature for in vitro biofilm formation by Salmonella spp. This temperature range facilitates the expression of biofilm-associated genes, contributing to the persistence of S. Infantis in the environment. This complicates biosecurity measures and makes disinfection protocols on the farm and in the production chain more difficult, posing serious public health concerns.

CRISPR and CRISPR-MVLST reveal conserved spacer distribution and high similarity among Salmonella enterica serovar Infantis genomes from Brazil and other countries.

Salmonella enterica serovar Infantis (S. Infantis) is a globally distributed non-typhoid serovar infecting humans and food-producing animals. Considering the zoonotic potential and public health importance of this serovar, strategies to characterizing, monitor and control this pathogen are of great importance. This study aimed to determine the genetic relatedness of 80 Brazilian S. Infantis genomes in comparison to 40 non-Brazilian genomes from 14 countries using Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and CRISPR-Multi-Locus Virulence Sequence Typing (CRISPR-MVLST). CRISPR spacers were searched using CRISPR-Cas++ and fimH and sseL alleles using BLAST and MEGA X. Results were analyzed using BioNumerics 7.6 in order to obtain similarity dendrograms. A total of 23 CRISPR1 and 11 CRISPR2 alleles formed by 37 and 26 types of spacers, respectively, were detected. MVLST revealed the presence of five fimH and three sseL alleles. CRISPR's similarity dendrogram showed 32 strain subtypes, with an overall similarity ≥ 78.6. The CRISPR-MVLST similarity dendrogram showed 37 subtypes, with an overall similarity ≥ 79.2. In conclusion, S. Infantis strains isolated from diverse sources in Brazil and other countries presented a high genetic similarity according to CRISPR and CRISPR-MVLST, regardless of their source, year, and/or place of isolation. These results suggest that both methods might be useful for molecular typing S. Infantis strains using WGS data.

Comparative whole genome analysis of face-derived Streptococcus infantis CX-4 unravels the functions related to skin barrier.

The skin microbiome is essential in guarding against harmful pathogens and responding to environmental changes by generating substances useful in the cosmetic and pharmaceutical industries. Among these microorganisms, Streptococcus is a bacterial species identified in various isolation sources. In 2021, a strain of Streptococcus infantis, CX-4, was identified from facial skin and found to be linked to skin structure and elasticity. As the skin-derived strain differs from other S. infantis strains, which are usually of oral origin, it emphasizes the significance of bacterial variation by the environment. This study aims to explore the unique characteristics of the CX-4 compared to seven oral-derived Streptococcus strains based on the Whole-Genome Sequencing data, focusing on its potential role in skin health and its possible application in cosmetic strategies. The genome of the CX-4 strain was constructed using PacBio Sequencing, with the assembly performed using the SMRT protocol. Comparative whole-genome analysis was then performed with seven closely related strains, utilizing web-based tools like PATRIC, OrthoVenn3, and EggNOG-mapper, for various analyses, including protein association analysis using STRING. Our analysis unveiled a substantial number of Clusters of Orthologous Groups in diverse functional categories in CX-4, among which sphingosine kinase (SphK) emerged as a unique product, exclusively present in the CX-4 strain. SphK is a critical enzyme in the sphingolipid metabolic pathway, generating sphingosine-1-phosphate. The study also brought potential associations with isoprene formation and retinoic acid synthesis, the latter being a metabolite of vitamin A, renowned for its crucial function in promoting skin cell growth, differentiation, and maintaining of skin barrier integrity. These findings collectively suggest the potential of the CX-4 strain in enhancing of skin barrier functionality. Our research underscores the potential of the skin-derived S. infantis CX-4 strain by revealing unique bacterial compounds and their potential roles on human skin.

Geographical and temporal distribution of multidrug-resistant Salmonella Infantis in Europe and the Americas.

Recently emerged S. Infantis strains carrying resistance to several commonly used antimicrobials have been reported from different parts of the globe, causing human cases of salmonellosis and with occurrence reported predominantly in broiler chickens. Here, we performed phylogenetic and genetic clustering analyses to describe the population structure of 417 S. Infantis originating from multiple European countries and the Americas collected between 1985 and 2019. Of these, 171 were collected from 56 distinct premises located in England and Wales (E/W) between 2009 and 2019, including isolates linked to incursions of multidrug-resistant (MDR) strains from Europe associated with imported poultry meat. The analysis facilitated the comparison of isolates from different E/W sources with isolates originating from other countries. There was a high degree of congruency between the outputs of different types of population structure analyses revealing that the E/W and central European (Germany, Hungary, and Poland) isolates formed several disparate groups, which were distinct from the cluster relating to the United States (USA) and Ecuador/Peru, but that isolates from Brazil were closely related to the E/W and the central European isolates. Nearly half of the analysed strains/genomes (194/417) harboured the IncFIB(pN55391) replicon typical of the "parasitic" pESI-like megaplasmid found in diverse strains of S. Infantis. The isolates that contained the IncFIB(pN55391) replicon clustered together, despite originating from different parts of the globe. This outcome was corroborated by the time-measured phylogeny, which indicated that the initial acquisition of IncFIB(pN55391) likely occurred in Europe in the late 1980s, with a single introduction of IncFIB(pN55391)-carrying S. Infantis to the Americas several years later. Most of the antimicrobial resistance (AMR) genes were identified in isolates that harboured one or more different plasmids, but based on the short-read assemblies, only a minority of the resistance genes found in these isolates were identified as being associated with the detected plasmids, whereas the hybrid assemblies comprising the short and long reads demonstrated that the majority of the identified AMR genes were associated with IncFIB(pN55391) and other detected plasmid replicon types. This finding underlies the importance of applying appropriate methodologies to investigate associations of AMR genes with bacterial plasmids.

Bifidobacterium longum subsp. infantis regulates Th1/Th2 balance through the JAK-STAT pathway in growing mice.

Objectives: Bifidobacterium longum subsp. infantis is a dominant bacterium in infant gut, which plays a critical role in maintaining the health and development of infants. This study investigated the abilities of eight different strains of B. longum subsp. infantis to regulate the T helper (Th)1/Th2 balance. Methods: Eight B. longum subsp. infantis strains, including I2MI (FJSWXI2MIM1), I4MI [FJSWXI4MI (CCFM1270)], I4MNI (FJSWXI4MNIM1), I5TI (FJSWXI5TIM1), I6TI (FJSWXI6TIM1), I8TI [FJSWXI8TI (CCFM1271)], I10TI [FJSWXI10TI (CCFM1272)], and B6MNI [BJSWXB6MNIM1 (CCFM1269)], were gavaged to BALB/C pups in both female (n = 8) and male (n = 8) mice starting from 1 to 3 weeks old (1 × 109 CFU/day/mice). Selected immune cells were assessed by immunofluorescence and flow cytometry. Cytokines and immunoglobulins were determined by ELISA. Bacterial and bifidobacterial communities were determined by 16S rRNA gene sequencing and bifidobacterial groEL sequencing. Results: B. longum subsp. infantis I4MI and I8TI were shown to increase the ration of colonic IgG2a/IgE in male mice (P < 0.05). B6MNI was demonstrated to significantly increase the levels of colonic IFN-γ and IgG2a, as well as the ratio of IgG2a/IgE in female mice (P < 0.05). It was also shown to significantly increase the ratio of colonic IgG2a/IgE (P < 0.05) and reduce the level of colonic IL-4 in male mice (P < 0.05). Furthermore, B6MNI was demonstrated to regulate colonic JAK/STAT pathway in both male and female mice. I4MI, I5TI, and B6MNI were shown to increase the relative abundance of Bifidobacterium and B. longum subsp. infantis in both male and female mice, whereas I8TI was only shown to increase the relative abundance of Bifidobacterium and B. longum subsp. infantis in male mice (P < 0.05). Conclusion: These results indicated supplementation with B. longum subsp. infantis in early infancy may regulate the Th1/Th2 immune balance, which may prevent the development of related diseases.

Salmonella in Coastal Birds in Chile: Detection of a Multidrug‐Resistant S. Infantis Bearing the blaCTX-M−65 Gene in a pESI‐Like Megaplasmid in Humboldt Penguins

Salmonella enterica is one of the most important foodborne pathogens worldwide, and the emergence of multidrug resistance (MDR) clones can aggravate its public health importance. Wildlife species may act as reservoirs of these clones, but their role is not well understood. In this study, faecal samples from shorebirds, with a focus on the endangered Humboldt penguin (Spheniscus humboldti), collected from five sites in central Chile with different levels of anthropogenic pressure were analysed to characterize antimicrobial resistant S. enterica serovars. Overall, Salmonella was isolated from 22 of the 595 samples (3.7%), with positivity ranging between 1.6% and 9.5%, depending on the sampling site. Four of the Salmonella isolates were retrieved from Humboldt penguin samples (1.4% positive samples in this species). Serovars Infantis (nine isolates), Typhimurium (six), Goldcoast (four), and Enteritidis, Agona, and Give (one isolate each) were identified. Resistance levels were the highest for sulphamethoxazole (13/21 isolates with a non‐wild‐type phenotype), ciprofloxacin, tetracycline, and trimethoprim (11/21 each). Whole‐genome sequencing performed on eight S. Infantis strains revealed that seven carried the plasmid replicon IncFIB (pN55391), indicating the presence of the pESI‐like megaplasmid, harbouring resistance determinants to multiple antimicrobial classes as well as heavy metal, biocides, and virulence‐related genes. Furthermore, five S. Infantis isolates that showed an ESBL phenotype carried the blaCTX-M−65 gene, three of which were detected in Humboldt penguin faeces. The finding of an international emerging S. Infantis clone in protected wildlife is of concern to environmental, animal, and public health specialists, supporting initiatives for an active surveillance of resistance and virulence traits in wildlife exposed to anthropogenic areas.

HMO-primed bifidobacteria exhibit enhanced ability to adhere to intestinal epithelial cells.

The ability of gut commensals to adhere to the intestinal epithelium can play a key role in influencing the composition of the gut microbiota. Bifidobacteria are associated with a multitude of health benefits and are one of the most widely used probiotics for humans. Enhanced bifidobacterial adhesion may increase host-microbe, microbe-nutrient, and/or microbe-microbe interactions, thereby enabling consolidated health benefits to the host. The objective of this study was to determine the ability of human milk oligosaccharides (HMOs) to enhance bifidobacterial intestinal adhesion in vitro. This study assessed the colonisation-promoting effects of HMOs on four commercial infant-associated Bifidobacterium strains (two B. longum subsp. infantis strains, B. breve and B. bifidum). HT29-MTX cells were used as an in vitro intestinal model for bacterial adhesion. Short-term exposure of four commercial infant-associated Bifidobacterium strains to HMOs derived from breastmilk substantially increased the adherence (up to 47%) of these probiotic strains. Interestingly, when strains were incubated with HMOs as a four-strain combination, the number of viable bacteria adhering to intestinal cells increased by >90%. Proteomic analysis of this multi-strain bifidobacterial mixture revealed that the increased adherence resulting from exposure to HMOs was associated with notable increases in the abundance of sortase-dependent pili and glycosyl hydrolases matched to Bifidobacterium bifidum. This study suggests that HMOs may prime infant gut-associated Bifidobacterium for colonisation to intestinal epithelial cells by influencing the expression of various colonization factors.

Safety, efficacy, and impact on gut microbial ecology of a Bifidobacterium longum subspecies infantis LMG11588 supplementation in healthy term infants: a randomized, double-blind, controlled trial in the Philippines.

Bifidobacterium longum subspecies infantis (B. infantis) may play a key role in infant gut development. This trial evaluated safety, tolerability, and efficacy of B. infantis LMG11588 supplementation. This randomized, placebo-controlled, double-blind study conducted in the Philippines included healthy breastfed and/or formula-fed infants (14-21 days old) randomized for 8 weeks to a control group (CG; n = 77), or any of two B. infantis experimental groups (EGs): low (Lo-EG; 1*108 CFU/day; n = 75) or high dose (Hi-EG; 1.8*1010 CFU/day; n = 76). Primary endpoint was weight gain; secondary endpoints included stooling patterns, gastrointestinal symptoms, adverse events, fecal microbiome, biomarkers, pH, and organic acids. Non-inferiority in weight gain was demonstrated for Hi-EG and Lo-EG vs. CG. Overall, probiotic supplementation promoted mushy-soft stools, fewer regurgitation episodes, and increased fecal acetate production, which was more pronounced in the exclusively breastfed infants (EBF) and positively correlated with B. infantis abundance. In EBF, fecal pro-inflammatory cytokines (IL-1 beta, IL-8) were reduced. Strain-level metagenomic analysis allowed attributing the increased abundance of B. infantis in EGs versus CG, to LMG11588 probiotic colonization. Colonization by autochthonous B. infantis strains was similar between groups. B. infantis LMG11588 supplementation was associated with normal infant growth, was safe and well-tolerated and promoted a Bifidobacterium-rich microbiota driven by B. infantis LMG11588 colonization without disturbing the natural dispersal of autochthonous B. infantis strains. In EBF, supplementation stimulated microbial metabolic activity and beneficially modulated enteric inflammation.

Rapid discrimination of Bifidobacterium longum subspecies based on MALDI-TOF MS and machine learning.

Although MALDI-TOF mass spectrometry (MS) is widely known as a rapid and cost-effective reference method for identifying microorganisms, its commercial databases face limitations in accurately distinguishing specific subspecies of Bifidobacterium. This study aimed to explore the potential of MALDI-TOF MS protein profiles, coupled with prediction methods, to differentiate between Bifidobacterium longum subsp. infantis (B. infantis) and Bifidobacterium longum subsp. longum (B. longum). The investigation involved the analysis of mass spectra of 59 B. longum strains and 41 B. infantis strains, leading to the identification of five distinct biomarker peaks, specifically at m/z 2,929, 4,408, 5,381, 5,394, and 8,817, using Recurrent Feature Elimination (RFE). To facilate classification between B. longum and B. infantis based on the mass spectra, machine learning models were developed, employing algorithms such as logistic regression (LR), random forest (RF), and support vector machine (SVM). The evaluation of the mass spectrometry data showed that the RF model exhibited the highest performace, boasting an impressive AUC of 0.984. This model outperformed other algorithms in terms of accuracy and sensitivity. Furthermore, when employing a voting mechanism on multi-mass spectrometry data for strain identificaton, the RF model achieved the highest accuracy of 96.67%. The outcomes of this research hold the significant potential for commercial applications, enabling the rapid and precise discrimination of B. longum and B. infantis using MALDI-TOF MS in conjunction with machine learning. Additionally, the approach proposed in this study carries substantial implications across various industries, such as probiotics and pharmaceuticals, where the precise differentiation of specific subspecies is essential for product development and quality control.

From farm to fork: Spread of a multidrug resistant Salmonella Infantis clone encoding blaCTX-M-1 on pESI-like plasmids in Central Italy

Salmonella enterica subsp. enterica serovar Infantis (S. Infantis) is one of the “top five Salmonella serovars” of clinical significance in the European Union (EU). Antimicrobial resistant and extended spectrum β-lactamase (ESBL) AmpC-producing S. Infantis have been described in food production systems and human clinical samples in Italy. Recently, an increase of MDR S. Infantis carrying blaCTX-M genes involved in 3rd generation cephalosporin resistance was noticed in the EU, including Italy, mainly due to the spread of S. Infantis harboring a pESI-like plasmid.The aim of this study was to investigate the occurrence of the S. Infantis pESI-like plasmid among antibiotic resistant S. Infantis strains isolated at different points of the food chain, and to provide a phylogenetic analysis to gain further insight on their transmission pathways from ‘farm to fork’.MDR S. Infantis strains (n. 35) isolated from 2016 to 2021 at different stages of the food chain (animals, food, food-related environments, and humans) were investigated with in depth molecular characterization using real-time PCR, S1 nuclease pulsed-field gel electrophoresis (S1-PFGE) and whole genome sequencing (WGS).Our study reported the occurrence of S. Infantis strains harboring pESI-like plasmids, carrying blaCTX-M-1 genes, in Central Italy, at different sampling points along the food chain. Results confirmed the presence of a plasmid with a molecular size around 224–310 kb, thus consistent with the pESI-like, in 97 % of the 35 samples investigated. Two variants of S. Infantis pESI-like IncFIB(K)_1_Kpn3 were detected, one associated with the European clone carrying blaCTX-M-1 (21 isolates) and the other associated with U.S. isolates carrying blaCTX-M-65 (2 isolates, pESI-like U.S. variant). The majority was resistant to 3rd generation cephalosporins but none of the strains tested positive for the carbapenemase encoding genes. A total of 118 virulence genes were identified in isolates harboring the pESI-like plasmid. cgMLST and SNP-based analysis revealed the presence of one main cluster, composed by strains isolated from the environment, animals, food and humans.The results of this investigation underline the importance of phylogenetic studies to monitor and understand pathogen and AMR spread in a One Health approach.

Detecting Virulence Genes Among Salmonella Serovar Infantis Isolated From Poultry Sources

Background: Salmonellosis is increasingly recognized as a worldwide public health concern. Salmonella Infantis can infect both humans and animals, including poultry. It has been one of the most reported isolated serovars from different parts of the world. Although some research has been carried out on the pathogenesis of S. Infantis, little scientific understanding of its pathogenesis is available. Objectives: This study aimed to analyze the virulence genes of S. Infantis recovered from different sources of poultry in Iran. Methods: Six virulence genes of 54 S. Infantis strains originated from broiler feces, poultry processing, and broiler carcasses were examined. Gene-specific polymerase chain reactions were designed and employed to detect the presence or absence of 6 important virulence genes (sopB, sopE, sitC, pefA, sipA, and spvC) in 54 S. Infantis isolates. Results: In this study, sopE, sitC, pefA, sipA, and sopB virulence genes were detected in 51(94.4%), 49(90.7%), 26(48.1%), 15(27.7%), and 5(9.2%) isolates, respectively. The spvC gene was not detected in any of the isolates. Conclusion: In the present study, a remarkably identical profile was found on virulence genes’ presence in isolates recovered from broiler feces and poultry processing plant sources, that is a public health concern. However, more S. Infantis isolates from various poultry sources, and human origin should be examined and analyzed. The findings of this survey can help the health researchers better understand the pathogenesis and epidemiology of S. Infantis in Iran.

Bifidobacterium infantis utilizes N-acetylglucosamine-containing human milk oligosaccharides as a nitrogen source

ABSTRACT Bifidobacterium longum subsp. infantis (B. infantis) utilizes oligosaccharides secreted in human milk as a carbohydrate source. These human milk oligosaccharides (HMOs) integrate the nitrogenous residue N-acetylglucosamine (NAG), although HMO nitrogen utilization has not been described to date. Herein, we characterize the B. infantis nitrogen utilization phenotype on two NAG-containing HMO species, LNT and LNnT. This was characterized through in vitro growth kinetics, incorporation of isotopically labeled NAG nitrogen into the proteome, as well as modulation of intracellular 2-oxoglutarate levels while utilizing HMO nitrogen. Further support is provided by comparative transcriptomics and proteomics that identified global regulatory networks deployed during HMO nitrogen utilization. The aggregate data demonstrate that B. infantis strains utilize HMO nitrogen with the potential to significantly impact fundamental and clinical studies, as well as enable applications.

Reaction of &lt;i&gt;Bifidobacterium longum&lt;/i&gt; subsp. &lt;i&gt;infantis&lt;/i&gt; Strain ATCC 15697 to Oxidative Stress

The genus Bifidobacterium is one of the predominant bacterial populations in human gut microbiota. Despite the increasing number of studies on the beneficial functionality of bifidobacteria for human health, knowledge about their antioxidant potential is still insufficient. The role of the antioxidant potential of bifidobacteria in maintaining the homeostasis of the intestinal microbiota of the host organism as a whole is an important task that requires solutions. For the first time, this paper presents the data of genomic, transcriptomic and proteomic analyses of probiotic strains Bifidobacterium longum subsp. infantis ATCC 15697 after the action of oxidative stress. The growing culture of strain was exposed to hydrogen peroxide for 2 hours and oxygen for 2 and 4 hours. Preliminary genome analysis of the strain showed the presence of 18 genes encoding a known protein with antioxidant function, as in other complied genomes of B. longum subsp. infantis strains available in the international database. The complete transcriptome analysis revealed an increase in transcript levels by more than two times for 6 genes with a known antioxidant function. The data of quantitative proteomic analysis showed an increase in protein levels by more than two times for five enzymes with a known antioxidant function. 28 other proteins with increased levels more than twice were identified in the cells of the growing culture in response to the long action of oxygen. These proteins can be involved in the processes of the cell’s response to stress, the amino acids, nucleotides metabolism and transport processes. Six proteins with unknown functions, which may play a significant role in the antioxidant response of anaerobic bifidobacteria, were found to have high levels in the cells after the action of stress. The obtained data are supposed to be used in the selection of B. longum subsp. infantis strains and the creation of pharmacobiotics able to correct the composition of the microbiota.

Fucosylated Human Milk Oligosaccharides Drive Structure-Specific Syntrophy between Bifidobacterium infantis and Eubacterium hallii within a Modeled Infant Gut Microbiome.

Fucosylated human milk oligosaccharides (fHMOs) are metabolized by Bifidobacterium infantis and promote syntrophic interactions between microbiota that colonize the infant gut. The role of fHMO structure on syntrophic interactions and net microbiome function is not yet fully understood. Metabolite production and microbial populations are tracked during mono- and co-culture fermentations of 2'fucosyllactose (2'FL) and difucosyllactose (DFL) by two B. infantis strains and Eubacterium hallii. This is also conducted in an in vitro modeled microbiome supplemented by B. infantis and/or E. hallii. Metabolites are quantified by high performance liquid chromatography. Total B. infantis and E. hallii populations are quantified through qRT-PCR and community composition through 16S amplicon sequencing. Differential metabolism of 2'FL and DFL by B. infantis strains gives rise to strain- and fHMO structure-specific syntrophy with E. hallii. Within the modeled microbial community, fHMO structure does not strongly alter metabolite production in aggregate, potentially due to functional redundancy within the modeled community. In contrast, community composition is dependent on fHMO structure. Whereas short chain fatty acid production is not significantly altered by the specific fHMO structure introduced to the modeled community, specific fHMO structure influences the composition of the gut microbiome.

Bifidobacterium longum subsp. infantis utilizes human milk urea to recycle nitrogen within the infant gut microbiome

ABSTRACT Human milk guides the structure and function of microbial commensal communities that colonize the nursing infant gut. Indigestible molecules dissolved in human milk establish a microbiome often dominated by bifidobacteria capable of utilizing these substrates. Interestingly, urea accounts for ~15% of total human milk nitrogen, representing a potential reservoir for microbiota that may be salvaged for critical metabolic operations during lactation and neonatal development. Accordingly, B. infantis strains are competent for urea nitrogen utilization, constituting a previously hypothetical phenotype in commensal bacteria hosted by humans. Urease gene expression, downstream nitrogen metabolic pathways, and enzymatic activity are induced during urea utilization to yield elevated ammonia concentrations. Moreover, biosynthetic networks relevant to infant nutrition and development are transcriptionally responsive to urea utilization including branched chain and other essential amino acids. Importantly, isotopically labeled urea nitrogen is broadly distributed throughout the expressed B. infantis proteome. This incisively demonstrates that the previously inaccessible urea nitrogen is incorporated into microbial products available for infant host utilization. In aggregate, B. infantis possesses the requisite phenotypic foundation to participate in human milk urea nitrogen recycling within its infant host and thus may be a key contributor to nitrogen homeostasis early in life.

Antimicrobial Resistance and Genomic Characterization of Salmonella Infantis from Different Sources

The epidemiology of Salmonella Infantis is complex in terms of its distribution and transmission. The continuous collection and analysis of updated data on the prevalence and antimicrobic resistance are essential. The present work aimed to investigate the antimicrobial resistance and the correlation among S. Infantis isolates from different sources through the multiple-locus variable-number of tandem repeat (VNTR) analysis (MLVA). A total of 562 Salmonella strains isolated from 2018 to 2020 from poultry, humans, swine, water buffalo, mussels, cattle, and wild boar were serotyped, and 185 S. Infantis strains (32.92%) were identified. S. Infantis was commonly isolated in poultry and, to a lesser extent, in other sources. The isolates were tested against 12 antimicrobials, and a high prevalence of resistant strains was recorded. S. Infantis showed high resistance against fluoroquinolones, ampicillin, and tetracycline, which are commonly used in human and veterinary medicine. From all S. Infantis isolates, five VNTR loci were amplified. The use of MLVA was not sufficient to understand the complexity of the epidemiological relationships between S. Infantis strains. In conclusion, an alternative methodology to investigate genetic similarities and differences among S. Infantis strains is needed.

Antibacterial activity of cinnamon oil against multidrug-resistant Salmonellaserotypes and anti-quorum sensing potential

The antimicrobial resistance due to Salmonella and other foodborne pathogenic microorganisms, witnessed in recent years, has become a significant health concern. Bacteria use chemical signals to communicate each other and regulate their behavior including virulence. Depending increased antibiotic resistance, new drug development strategies being investigating and the usability of active ingredients of various medicinal and aromatic plants is especially tested as an alternative. The aim of this study was to determine the anti-quorum sensing (QS) activity of cinnamon oil (CO) on pigment production of Chromobacterium violaceum and to evaluate antibacterial activity against multidrug resistant (MDR) S. enterica serotypes. Anti QS activity was tested using biosensor strain and antibacterial activity was determined by microdilution method according to EUCAST standards. CO was found effective on QS mechanisms of Chromobacterium violaceum with pigment inhibition. Nineteen foodborne pathogens isolated from different poultry/cow sourced foods and serotyped as S. enterica serovar Infantis (15), Kentucky (1), Newport (1), Telaviv (1), and Typhimurium (1). S. enterica Infantis strains were found resistant to three or more antibiotics and categorized as MDR. The results concluded that CO has strong antibacterial activity against all S. enterica serotypes with MIC between 0.125 µg ml-1 and 1.0 µg ml-1. This research demonstrates CO is a potential candidate for developing new antimicrobial agents, antiseptic solutions or natural food preservatives against MDR Salmonella isolates also a potential as an anti-QS agent.