Diffusion and persistence of multidrug resistant Salmonella Typhimurium strains phage type DT120 in southern Italy

The Role of Stakeholders' Understandings in Emerging Antimicrobial Resistance: A One Health Approach

The increasing misuse of antibiotics in human and veterinary medicine and in agroecosystems and the consequent selective pressure of resistant strains lead to multidrug resistance (AMR), an expanding global phenomenon. Indeed, this phenomenon represents a major public health target with significant clinical implications related to increased morbidity and mortality and prolonged hospital stays. The current presence of microorganisms multi-resistant to antibiotics isolated in patients is a problem because of the additional burden of disease it places on the most fragile patients and the difficulty of finding effective therapies. In recent decades, international organizations like the World Health Organization (WHO) and the European Centre for Disease Prevention and Control (ECDC) have played significant roles in addressing the issue of AMR. The ECDC estimates that in the European Union alone, antibiotic resistance causes 33,000 deaths and approximately 880,000 cases of disability each year. The epidemiological impact of AMR inevitably also has direct economic consequences related not only to the loss of life but also to a reduction in the number of days worked, increased use of healthcare resources for diagnostic procedures and the use of second-line antibiotics when available. In 2015, the WHO, recognising AMR as a complex problem that can only be addressed by coordinated multi-sectoral interventions, promoted the One Health approach that considers human, animal, and environmental health in an integrated manner. In this review, the authors try to address why a collaboration of all stakeholders involved in AMR growth and management is necessary in order to achieve optimal health for people, animals, plants, and the environment, highlighting that AMR is a growing threat to human and animal health, food safety and security, economic prosperity, and ecosystems worldwide.

Comparative virulence of the worldwide ST19 and emergent ST213 genotypes of Salmonella enterica serotype Typhimurium strains isolated from food

Salmonella enterica Typhimurium represents one of the most frequent causal agents of food contamination associated to gastroenteritis. The sequence type ST19 is the founder and worldwide prevalent genotype within this serotype, but its replacement by emerging genotypes has been recently reported. Particularly, the ST213 genotype has replaced it as the most prevalent in clinical and contaminated food samples in Mexico and has been recently reported in several countries. In this study, the in vitro and in vivo virulence of ST213 and ST19 strains isolated from food samples in Mexico was evaluated. Three out of the five analyzed ST213 strains, showed a greater internalization capacity and increased secretion of interleukins IL-8 and IL-6 of Caco-2 cells than the ST19 strains. Microbiological counts in feces and tissues showed the ability of all strains tested to establish infection in the rat model. The ST213 strains also caused histopathological damage, characteristic of gastroenteritis in Wistar rats. In contrast to the in vitro result, one of the ST19 strains showed marked damage in the test animals. The ST213 genotype strains showed in vitro and in vivo virulence variability, but significantly higher than the observed in the ST19 genotype strains, thus such emergent genotype represents a public health concern.

Identification and Characterisation of pST1023 A Mosaic, Multidrug-Resistant and Mobilisable IncR Plasmid

We report the identification and characterisation of a mosaic, multidrug-resistant and mobilisable IncR plasmid (pST1023) detected in Salmonella ST1023, a monophasic variant 4,[5],12:i: strain of widespread pandemic lineage, reported as a Southern European clone. pST1023 contains exogenous DNA regions, principally gained from pSLT-derivatives and IncI1 plasmids. Acquisition from IncI1 included oriT and nikAB and these conferred the ability to be mobilisable in the presence of a helper plasmid, as we demonstrated with the conjugative plasmids pST1007-1D (IncFII) or pVC1035 (IncC). A sul3-associated class 1 integron, conferring resistance to aminoglycosides, chloramphenicol and trimethoprim-sulphonamides, was also embedded in the acquired IncI1 DNA segment. pST1023 also harboured an additional site-specific recombination system (rfsF/rsdB) and IS elements of the IS1, IS5 (IS903 group) and IS6 families. Four of the six IS26 elements present constituted two pseudo-compound-transposons, named PCT-sil and PCT-Tn10 (identified here for the first time). The study further highlighted the mosaic genetic architecture and the clinical importance of IncR plasmids. Moreover, it provides the first experimental data on the ability of IncR plasmids to be mobilised and their potential role in the horizontal spread of antimicrobial-resistant genes.

Potential impact of functional biomolecules-enriched foods on human health: A randomized controlled clinical trial

Naturally occurring milk compounds have recently been investigated for their health-promoting properties; in fact, their anti-microbial, immuno-modulatory, antioxidant and anti-thrombotic activities, have increasingly gained interest within the scientific community. We have reported a translational, randomized, controlled clinical trial (RCT) on human subjects with a moderate to high cardiovascular risk, and a body mass index (BMI) >25.1 kg/m2, to evaluate the clinical impact of biomolecules-enriched Mediterranean Buffalo (Bubalus bubalis) milk and its derived dairy foods, produced with innovative breeding techniques. The experimental arm involved patients that followed a diet including the above-described products (treated group; n= 11); the control arm was based on a diet including cow milk and its dairy products (control group; n= 9). The results of this study have been statistically evaluated, pointing out a specific significance related to the comparative analysis of the blood pressure among the 2 arms; in fact, this value showed a significant improvement in an extremely short experimental time. Nevertheless, this study also reported not-significant results that were indicative of an interesting and promising tendency in modulating specific diet-depending haematological and biomedical values. In conclusion, this RCT has assessed that the foods derived from buffalo milk naturally enriched with biomolecules, was able to improve the overall blood glucose levels, the BMI and the body weight. These preliminary results are suitable for the design of future strategies in the prevention of cardiometabolic diseases, thus improving the overall quality of life and the policies of healthcare management.

Antimicrobial Drug-Resistant Salmonella in Urban Cats: Is There an Actual Risk to Public Health?

The present study was undertaken to investigate the presence of Salmonella spp. in the faeces of client-owned cats in urban areas and to evaluate the risk that is posed to public health. Fresh faecal samples were collected directly from the rectums from 53 diarrhoeic and 32 non-diarrhoeic cats. The samples were individually screened for the presence of Salmonella spp. using standard methods and, in the case of positive findings, the resulting typical colonies were then biochemically confirmed using the VITEK^®2 automated system. Subsequently, all of the Salmonella spp. isolates were molecularly tested for the presence of the invA gene. All of the isolates were serotyped using the slide agglutination technique according to the White–Kauffmann–Le Minor scheme. The phenotypic antimicrobial susceptibility profile of the isolated strains was obtained from the VITEK^®2 system using specific cards from the Gram-negative bacteria. A total of 16 of the samples (18.82%) tested positive for Salmonella spp. according to conventional and molecular testing methods. Serotyping of the Salmonella isolates showed the presence of three serotypes, namely S. enteritidis (n = 9; 56.3%), S. typhimurium (n = 4; 25%), and S. kentucky (n = 3; 18.8%). All of the tested strains showed strong resistance towards cefazolin, cefepime, ceftazidime, and ceftriaxone. Additionally, resistance (listed in descending order of strength) was observed to trimethoprim/sulfamethoxazole (11/16; 68.8%), ampicillin (10/16; 62.5%), ampicillin/sulbactam (9/16; 56.3%), gentamicin (9/16; 56.3%), nitrofurantoin (8/16; 50.0%), and amikacin (5/16; 31.3%). No resistance was expressed against ciprofloxacin, ertapenem, imipenem, levofloxacin, piperacillin/tazobactam, and tobramycin. The results of this study highlight a substantial public health issue and medical concern, especially in vulnerable people, such as children, the elderly, and immunocompromised individuals.

Rebalancing the Oral Microbiota as an Efficient Tool in Endocrine, Metabolic and Immune Disorders

The current treatment and prevention procedures of oral disorders follow a very targeted approach considering mouth and its structures as a system that is completely independent, than the rest of the body. The main therapeutic approach is to keep the levels of oral bacteria and hygiene in an acceptable range compatible with oral-mouth health, completely separated from systemic microbial homeostasis (eubiosis vs dysbiosis). This can negatively impact the diagnosis of a more complex systemic disease and its progression. Dysbiosis occurs as a consequence of imbalance in oral and gut microbiota which leads to cardiovascular diseases, diabetes mellitus, rheumatoid arthritis, and Alzheimer's disease, as reported in current literature. Likewise, there is a need to highlight and develop a novel philosophical approach in the treatments for oral diseases that will necessarily involve nonconventional approaches.

Antimicrobial resistance gene shuffling and a three-element mobilisation system in the monophasic Salmonella typhimurium strain ST1030

In this study we describe the genetic elements and the antimicrobial resistance units (RUs) harboured by the Salmonella Typhimurium monophasic variant 1,4,[5],12:i:- strain ST1030. Of the three identified RUs two were chromosomal, RU1 (IS26-bla_TEM-1-IS26-strAB-sul2- IS26) and RU2 (IS26-tetR(B)-tetA(B)-ΔIS26), and one, RU3 (a sul3-associated class 1 integron with cassette array dfrA12-orfF-aadA2-cmlA1-aadA1), was embedded in a Tn21-derived element harboured by the conjugative I1 plasmid pST1030-1A. IS26 elements mediated the antimicrobial resistance gene (ARG) shuffling and this gave rise to pST1030-1A derivatives with different sets of ARGs. ST1030 also harboured two ColE1-like plasmids of which one, pST1030-2A, was mobilisable and the target of an intracellular translocation of the Tn21-derived element; the second (pST1030-3) was an orphan mob-associated oriT plasmid co-transferred with pST1030-1A and pST1030-2A. pST1030-2A and pST1030-3 also carried a parA gene and a type III restriction modification system, respectively. Overall analysis of our data reinforces the role played by IS26, Tn21-derived elements and non-conjugative plasmids in the spread of ARGs and supplies the first evidence, at least in Salmonella, for the identification of a natural isolate harbouring a three-element mobilisation system in the same cell.

Management of Endodontic and Periodontal Lesions: the Role of Regenerative Dentistry and Biomaterials

Regenerative dentistry represents a novel interdisciplinary approach involving biomaterials, several molecules and mesenchymal stem cells (MSCs), preferably derived from oral tissues. The pivotal role of MSCs depends on the fact that they can differentiate into different cell lineages and have the strategic role to release bioactive substances that stimulate the renewal and regeneration of damaged tissues. The role of regenerative dentistry is promising in all the branches of dentistry: the most intriguing application is related to the management of endodontic and periodontal defects, overcoming the surgical approach and the implantology as a consequence of a poorly efficient therapeutic plan.

Antibiotic Resistance in Salmonella Typhimurium Isolates Recovered From the Food Chain Through National Antimicrobial Resistance Monitoring System Between 1996 and 2016

Salmonella is a major foodborne pathogen which causes widespread contamination and infection worldwide. Salmonella Typhimurium is one of the leading serovars responsible for human and animal salmonellosis, globally. The increasing rate of antibiotic resistance in Salmonella Typhimurium poses a significant global concern, and an improved understanding of the distribution of antibiotic resistance patterns in Salmonella Typhimurium is essential for choosing the suitable antibiotic for the treatment of infections. To evaluate the roles of animal and human in antibiotic resistance dissemination, this study aims to categorize 11,447 S. Typhimurium strains obtained across the food-chain, including food animals, retail meats and humans for 21 years in the United States by analyzing minimum inhibitory concentrations (MICs) values for 27 antibiotics. Random Forest Algorithm and Hierarchical Clustering statistics were used to group the strains according to their minimum inhibitory concentration values. Classification and Regression Tree analysis was used to identify the best classifier for human- and animal-populations’ isolates. We found the persistent population or multi-drug resistant strains of S. Typhimurium across the four time periods (1996∼2000, 2001∼2005, 2006∼2010, 2011∼2016). Importantly, we also detected that there was more diversity in the MIC patterns among S. Typhimurium strains isolated between 2011 and 2016, which suggests significant emergence of diversified multi-drug resistant strains. The most frequently observed (43%) antibiotic resistance patterns found in S. Typhimurium were tetra-resistant pattern ASSuT (ampicillin, streptomycin, sulfonamides, and tetracycline) and the penta-resistant pattern ACSSuT (ampicillin, chloramphenicol, streptomycin, sulfonamides, and tetracycline). Animals (mainly swine and bovine) are the major source for these two frequently found antibiotic resistance patterns. The occurrence of antibiotic resistant strains from humans and chicken is alarming. Strains were mostly susceptible to fluoroquinolones. Together, this study helped in understanding the expansion of dynamics of antibiotic resistance of S. Typhimurium and recommended fluoroquinolones as a possible treatment options against S. Typhimurium infection.

IS26 mediated antimicrobial resistance gene shuffling from the chromosome to a mosaic conjugative FII plasmid

In the present study we report the identification of a sul3-associated class 1 integron containing the dfrA12-orfF-aadA2-cmlA1-aadA1-qacH array embedded in a Tn21-derived element that is part of a conjugative FII plasmid named pST1007-1A. The plasmid was identified in the Salmonella Typhimurium strain ST1007, a member of a clinically relevant clonal MDR lineage diffuse in Italy. ST1007 exhibited resistance to ampicillin, chloramphenicol, streptomycin, sulphamethoxazole, tetracycline and trimethoprim encoded by bla_TEM-1, cmlA1, (aadA1, aadA2, strAB), (sul2, sul3), tet(B) and dfrA12 genes, respectively. Apart from pST1007-1A, ST1007 also harbours two chromosome-integrated resistance units RU1 (bla_TEM-1-sul2-strAB) and RU2 (tet(B)), flanked by IS26 elements. RU1 and RU2 were able to move as translocatable units, respectively TU1 and TU2, and integrate via IS26 mediated recombination into pST1007-1A. A family of conjugative plasmids, harbouring different sets of antimicrobial resistance genes (ARG) was then generated: pST1007-1B (dfrA12-aadA2-cmlA1-aadA1-sul3- tet(B)), pST1007-1C (dfrA12-aadA2-cmlA1-aadA1-sul3-bla_TEM-1-sul2-strAB), pST1007-1D (bla_TEM-1-sul2-strAB), pST1007-1E (tet(B)) and pST1007-1F (dfrA12-aadA2-cmlA1-aadA1-sul3- tet(B) -bla_TEM-1-sul2-strAB). pST1007-1A is also a mosaic plasmid containing two distinct DNA fragments acquired from I1 plasmids through recombination within the repA4, rfsF and repeat-3 sites. This study further highlights the role played by IS26 in intracellular ARGs shuffling. Moreover, attention has been focused on recombination hot spots that might play a key role in generating mosaic plasmids.

Whole genome sequencing of multidrug-resistant Salmonella enterica serovar Typhimurium isolated from humans and poultry in Burkina Faso

Background

Multidrug-resistant Salmonella is an important cause of morbidity and mortality in developing countries. The aim of this study was to characterize and compare multidrug-resistant Salmonella enterica serovar Typhimurium isolates from patients and poultry feces.

Methods

Salmonella strains were isolated from poultry and patients using standard bacteriological methods described in previous studies. The strains were serotype according to Kaufmann-White scheme and tested for antibiotic susceptibility to 12 different antimicrobial agents using the disk diffusion method. The whole genome of the S. Typhimurium isolates was analyzed using Illumina technology and compared with 20 isolates of S. Typhimurium for which the ST has been deposited in a global MLST database.The ResFinder Web server was used to find the antibiotic resistance genes from whole genome sequencing (WGS) data. For comparative genomics, publicly available complete and draft genomes of different S. Typhimurium laboratory-adapted strains were downloaded from GenBank.

Results

All the tested Salmonella serotype Typhimurium were multiresistant to five commonly used antibiotics (ampicillin, chloramphenicol, streptomycin, sulfonamide, and trimethoprim). The multilocus sequence type ST313 was detected from all the strains. Our sequences were very similar to S. Typhimurium ST313 strain D23580 isolated from a patient with invasive non-typhoid Salmonella (NTS) infection in Malawi, also located in sub-Saharan Africa. The use of ResFinder web server on the whole genome of the strains showed a resistance to aminoglycoside associated with carriage of the following resistances genes: strA, strB, and aadA1; resistance to β-lactams associated with carriage of a bla_TEM-1B genes; resistance to phenicol associated with carriage of catA1 gene; resistance to sulfonamide associated with carriage of sul1 and sul2 genes; resistance to tetracycline associated with carriage of tet B gene; and resistance to trimethoprim associated to dfrA1 gene for all the isolates.

Conclusion

The poultry and human isolates were genetically similar showing a potential food safety risk for consumers. Our finding of multidrug-resistant S. Typhimurium ST313 in poultry feces calls for further studies to clarify the potential reservoirs of this emerging pathogen.

Integron types, gene cassettes and antimicrobial resistance profile of Acinetobacter baumannii isolated from BAL samples in Babol, north of Iran

Multi-drug resistant isolates of Acinetobacter baumannii have created therapeutic problems worldwide. This current study was intended to determine the Integron types, gene cassettes and antimicrobial resistance profile of A. baumannii isolated from BAL samples in Babol, north of Iran. During a 15-month period, 35 A. baumannii isolates were studied. Different classes of antimicrobial agents were used to determine the resistance ratios. Multiplex-PCR was used to detect different types of integrons and associated gene cassettes. The resistance rates to GM, FEP, AK, TOB, CP, PIP, SAM, IPM, SXT, CTX, CAZ, CL, TIM, MEM, and TZP were 85.7%, 100%, 91.4%, 68.5%, 94.3%, 88.5%, 97.1%, 94.3%, 100%, 100%, 100%, 0.0%, 91.4%, 94.3% and 91.4%, respectively. The distribution analysis of int genes showed that 25.7%, 88.6% and 28.6% of isolates carried the intI, intII and intIII genes, respectively. The prevalence of aadB, dfrA1, bla-OXA₃₀ and aadA1 genes were 94.3%, 77.1%, 40% and 5.7%, respectively. The current study showed that a high level of A. baumannii isolates harbor integrons in our therapeutic center, which may lead to distribution of multiple antimicrobial resistance. The different types of gene cassette arrays in the present study highlight the important role of geographical features in MDR isolates dissemination which could be credited to different profiles of drug consumption in different areas. The findings emphasized that the need for continuous surveillance to prevent distribution of multidrug resistance among A. baumannii strains in Iran.

A novel group of IncQ1 plasmids conferring multidrug resistance

The IncQ is a group of non-conjugative but mobilisable plasmids that are found and stably maintained in a wide range of bacteria contributing to the spread of antimicrobial resistance genes and to the insurgence of multidrug resistant bacteria. Here we report the identification, in clinical Salmonella Typhimurium strains, of an IncQ1 plasmid (pNUC) which confers resistance to sulfamethoxazole, streptomycin and tetracycline through the presence of sul2, strAB and tetA genes, respectively. pNUC was detected in five multidrug resistant S. Typhimurium strains collected in Southern Italy from various hospitals and years of isolation. Bioinformatics analyses highlighted the presence of pNUC-like plasmids in pathogenic bacteria of various Enterobacteriaceae genera or species. Taken as a whole, these plasmids constitute a novel group of IncQ1 plasmids that might have originated through recombination events between a tetR-tetA gene cluster (possibly derived from a Tn1721) and a recipient IncQ1 plasmid related to RSF1010. Our findings raise concerns regarding the possible contribution of the newly identified group of IncQ1 plasmids to the spread of tetracycline resistance.