Prevalence of streptomycin and tetracycline resistance and increased transmissible third-generation cephalosporin resistance in Salmonella enterica isolates derived from food handlers in Japan from 2006 to 2021.

AIMS: The increasing prevalence of AmpC ß-lactamase (AmpC)- and extended-spectrum ß-lactamase (ESBL)- producing food pathogens is a serious public health concern. AmpC- and ESBL-producing Salmonella species pose a high risk of food contamination. This study aimed to investigate changes in the prevalence of Salmonella among food handlers in Japan from 2006 to 2021 using 100 randomly selected isolates from 2006, 2012, 2018, and 2021 with different serotypes and antimicrobial resistance patterns. METHODS AND RESULTS: The average Salmonella isolation rate was 0.070% (19 602/27 848 713). Serotyping revealed that the most common serotypes were Enteritidis in 2006, Infantis in 2012, Agoueve/Cubana in 2018, and Schwarzengrund in 2021. Antimicrobial susceptibility testing showed that Salmonella isolates exhibited the highest resistance to streptomycin (<40%), followed by tetracycline (<20%-40%). Moreover, 6% of the Salmonella isolates produced cephalosporinases with the blaCMY-2, blaCTX-M-14, and blaTEM genes. The annual incidence of cephalosporin resistance has increased. Plasmid conjugation assays revealed that cephalosporin-resistant Salmonella spp. transmitted their resistance to Escherichia coli. Additionally, plasmid genome analysis showed that the insertion sequence IS26 was encoded in the upstream and downstream regions of blaCTX-M-14 and qnrS1 in the IncHI1 plasmid, which could be transmitted to other bacteria. CONCLUSIONS: The tested Salmonella isolates showed high resistance to specific antibiotics, with differences in resistance depending on the serotype. Further increase and spread of transmissible cephalosporin-resistant strains should be noted.

Dissemination of IncC plasmids in Salmonella enterica serovar Thompson recovered from seafood and human diarrheic patients in China.

Salmonella Thompson is a prevalent foodborne pathogen and a major threat to food safety and public health. This study aims to reveal the dissemination mechanism of S. Thompson with co-resistance to ceftriaxone and ciprofloxacin. In this study, 181 S. Thompson isolates were obtained from a retrospective screening on 2118 serotyped Salmonella isolates from foods and patients, which were disseminated in 12 of 16 districts in Shanghai, China. A total of 10 (5.5 %) S. Thompson isolates exhibited resistance to ceftriaxone (MIC ranging from 8 to 32 µg/mL) and ciprofloxacin (MIC ranging from 2 to 8 µg/mL). The AmpC ß-lactamase gene blaCMY-2 and plasmid-mediated quinolone resistance (PMQR) genes of qnrS and qepA were identified in the 9 isolates. Conjugation results showed that the co-transfer of blaCMY-2, qnrS, and qepA occurred on the IncC plasmids with sizes of ∼150 (n = 8) or ∼138 (n = 1) kbp. Three typical modules of ISEcp1-blaCMY-2-blc-sugE, IS26-IS15DIV-qnrS-ISKpn19, and ISCR3-qepA-intl1 were identified in an ST3 IncC plasmid pSH11G0791. Phylogenetic analysis indicated that IncC plasmids evolved into Lineages 1, 2, and 3. IncC plasmids from China including pSH11G0791 in this study fell into Lineage 1 with those from the USA, suggesting their close genotype relationship. In conclusion, to our knowledge, it is the first report of the co-existence of blaCMY-2, qnrS, and qepA in IncC plasmids, and the conjugational transfer contributed to their dissemination in S. Thompson. These findings underline further challenges for the prevention and treatment of Enterobacteriaceae infections posed by IncC plasmids bearing blaCMY-2, qnrS, and qepA.

Prevalence of Antimicrobial Resistance and Clonal Relationship in ESBL/AmpC-Producing Proteus mirabilis Isolated from Meat Products and Community-Acquired Urinary Tract Infection (UTI-CA) in Southern Brazil.

The present study aimed to evaluate the prevalence of antimicrobial resistance and clonal relationships in Proteus mirabilis isolated from chicken meat, beef, pork, and community-acquired urinary tract infections (UTI-CA). Chicken meat isolates showed the highest multidrug resistance (MDR), followed by those from pork and UTI-CA, whereas beef had relatively few MDR strains. All sources had strains that carried blaCTX-M-65, whereas blaCTX-M-2 and blaCMY-2 were only detected in chicken meat and UTI-CA isolates. This indicates that chicken meat should be considered an important risk factor for the spread of P. mirabilis carrying ESBL and AmpC. Furthermore, ESBL/AmpC producing strains were resistant to a greater number of antimicrobials and possessed more resistance genes than non-producing strains. In addition, the antimicrobial resistance genes qnrD, aac(6')-Ib-cr, sul1, sul2, fosA3, cmlA, and floR were also found. Molecular typing showed a genetic similarity between chicken meat and UTI-CA isolates, including some strains with 100% similarity, indicating that chicken can be a source of P. mirabilis causing UTI-CA. It was concluded that meat, especially chicken meat, can be an important source of dissemination of multidrug-resistant P. mirabilis in the community.

Abundance of colistin-resistant Escherichia coli harbouring mcr-1 and extended-spectrum ß-lactamase-producing E. coli co-harbouring blaCTX-M-55 or -65 with blaTEM isolates from chicken meat in Vietnam.

Although the spread of plasmid-mediated antibiotic-resistant bacteria is a public health concern, food contamination with plasmid-mediated antibiotic-resistant Escherichia coli in Vietnam has not been well investigated. This study aimed to describe the prevalence of colistin-resistant, carbapenem-resistant, and endemic blaCTX-M in extended-spectrum ß-lactamase (ESBL) producing E. coli isolates. Colistin and carbapenem-resistant ESBL-producing E. coli were isolated from chickens in Vietnam and Japan. Colistin-resistant and AmpC/ESBL-producing E. coli (52% and 93%, respectively) were detected in chickens from Vietnam, in comparison to 52.7%, AmpC/ESBL-producing E. coli found in chicken from Japan. Carbapenem-resistant E. coli has not been isolated in Vietnam and Japan. Genotyping revealed that colistin-resistant E. coli harboured mcr-1, and most of the AmpC/ESBL-related genes were blaCTX-M-55 and blaCTX-M-65 together with blaTEM in Vietnamese chickens and blaCMY-2 in Japanese chickens. Multi-drug resistance analysis showed that ESBL-producing E. coli isolates had greater resistance to quinolones, streptomycin, and chloramphenicol than colistin-resistant E. coli isolates from Vietnam, suggesting the selection of multiple antibiotic resistance genes in ESBL-producing E. coli. In conclusion, colistin-resistant E. coli was detected in approximately half of the chicken samples, the majority of which harboured mcr-1. The high prevalence of ESBL-producing E. coli has remained constant in the last 5 years. The predominant blaCTX-M in ESBL-producing E. coli was blaCTX-M-55 or blaCTX-M-65, with the coexistence of blaTEM in Vietnam. These results can be implemented in monitoring systems to overcome the development of antimicrobial resistance.

Detection of blaTEM, blaCTX-M, blaCMY, and blaSHV Genes Among Extended-Spectrum Beta-Lactamase-Producing Escherichia coli Isolated from Migratory Birds Travelling to Bangladesh.

Extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli cause severe health hazards. Migratory birds are reservoirs and transmitters of many pathogens including ESBL-producing E. coli. To examine migratory birds as potential carriers of ESBL-producing E. coli and E. coli-carrying antibiotic resistance genes, 55 PCR-positive E. coli isolates were screened using the disk diffusion method, double-disk synergy test, and further polymerase chain reaction (PCR) tests. Genes encoding resistance to tetracycline [tetA, 100% (35/35); tetB, 31.43% (11/35)], fluoroquinolone [qnrA, 35.71% (10/28); qnrB, 25% (7/28)], and streptomycin [aadA1, 90.24% (37/41)] were detected in the isolated E. coli. Of the 55 E. coli isolates, 21 (38.18%) were ESBL producers, and all of them were multidrug resistant. All the ESBL-producing E. coli isolates harbored at least two or more beta-lactamase genes, of which blaTEM, blaCMY, blaCTX-M, and blaSHV were detected in 95.24%, 90.48%, 85.71%, and 42.86% of isolates, respectively. All the beta-lactamase genes were present in four of the ESBL-producing E. coli isolates. Furthermore, 95.24% of ESBL-producing E. coli isolates were positive for one or more antibiotic resistance genes. To the best of our knowledge, this is the first study to detect E. coli-carrying antibiotic resistance genes including beta-lactamase blaCMY and blaSHV originating from migratory birds in Bangladesh. These results suggest that migratory birds are potential carriers of ESBL-producing E. coli along with other clinically important antibiotic resistance genes which may have detrimental impacts on human health.

Multidrug resistance IncC plasmid carrying blaCMY-97 in Shiga toxin-producing Escherichia coli ST215-H54 of ovine origin.

CMY-type ß-lactamases are the most reported plasmid-mediated AmpC (pAmpC), with the CMY-2-like group being the most clinically relevant described in Escherichia coli at human-animal-environment interface. Shiga toxin-producing E. coli (STEC) lineages are zoonotic pathogens commonly reported causing serious clinical conditions in humans, including severe diarrheagenic diseases. Therefore, this study aimed to investigate a multidrug-resistant (MDR) STEC isolate (A313) recovered from a healthy sheep and carrying mobile blaCMY-97, that encodes a pAmpC belonging to the CMY-2-like group. The A313 isolate exhibited a MDR profile to clinically relevant antimicrobials (i.e., cephalosporins, aminoglycosides, and fluoroquinolones), but reduced susceptibility to extended-spectrum cephalosporins and aztreonam. Besides, virulence genes (stx2, gad and iutA) were detected in A313, which belonged to ST215/CC10 and phylogenetic group A, whereas the fimH54 was identified. The blaCMY-97 gene and other antimicrobial resistance determinants [aph(6)-Id, aph(3″)-Ib, aac(3)-IId, aadA5, floR, tetA, sul1, and sul2], as well as genes encoding tolerance to mercury (merRTPCADE), were harbored by an IncC plasmid (named pA313-CMY-97, ~ 176 kb). A novel genetic context of blaCMY-2-like, in which a 208-bp ISEcp1 was truncated by an IS26 in the opposite orientation upstream of the blaCMY-97 gene (IS26-∆ISEcp1-blaCMY-97-blc-sugE-encR), was also identified in pA313-CMY-97. To the best of our knowledge, this is the first report on the acquisition of blaCMY-97 into a plasmid. Therefore, we reported ovine as reservoir of clinically relevant MDR bacteria carrying mobile blaCMY-97 with potential for zoonotic transmission.

Whole genome sequencing of Salmonella enterica serovar Saintpaul for elucidating the mechanisms of resistance to third generation cephalosporins.

An increase in the number of Salmonella enterica serovar Saintpaul observed in Singapore in 2015-2016 in humans was accompanied by increased resistance to third generation cephalosporins. We aimed to understand the genetic mechanisms contributing to this resistance. Whole genome sequencing using MiSeq was performed on 49 S. Saintpaul isolates collected between 2014-2016. Nanopore sequencing was also performed in an attempt to obtain a full genome of the plasmids. All but one S. Saintpaul isolates sequenced belonged to a single sequence type based on an in silico 7-gene multi-locus sequence typing scheme suggesting a clonal lineage. In total 27/49 were resistant to third generation cephalosporins as confirmed by the broth microdilution method; the resistance was due to the presence of either blaCTX-M-55 (n=23), blaCTX-M-27 (n=1) or blaCMY-2 (n=3) carried on a plasmid. Two isolates were also found to carry the mcr-1 gene on a different plasmid. Our study showed that all S. Saintpaul isolates resistant to third generation cephalosporins carried either blaCTX-M-55, blaCTX-M-27 or blaCMY-2 on a plasmid. Continuous monitoring of Salmonella serovars is warranted to track the potential spread of these plasmids.

Genetic analysis and plasmid-mediated blaCMY-2 in Salmonella and Shigella and the Ceftriaxone Susceptibility regulated by the ISEcp-1 tnpA-blaCMY-2-blc-sugE.

BACKGROUND: Nontyphoid Salmonella and Shigella can cause gastroenteritis in humans. Ceftriaxone (CRO) has been used to treat their infection, however, development of CRO resistance are often associated with plasmid-mediated blaCMY. Here, we investigated the presence of plasmid-mediated ISEcp-1 tnpA-blaCMY-2-blc-sugE and the role of these genes in regulation of CRO susceptibility in different hosts. METHODS: 194 strains of Salmonella serovars and Shigella were tested for CRO susceptibility. Non-susceptibility strains were examined for plasmid-mediated ISEcp-1 tnpA-blaCMY-2-blc-sugE by PCR amplification, Southern blot, and DNA sequencing. The plasmid profiles were determined by HindIII-digested restriction fragment length polymorphism (RFLP). Four recombinant plasmids with different genes from ISEcp-1 tnpA-blaCMY-2-blc-sugE were constructed and then were transferred into Escherichia coli and different Salmonella serovars to evaluate the CRO susceptibility. RESULTS: Among 20 CRO-nonsusceptible isolates of Salmonella Choleraesuis (5), S. Typhimurium (4), S. Mons (1), S. Stanley (2) and Shigella sonnei (8) with plasmid-mediated blaCMY-2, 19 isolates carried the ISEcp-1 tnpA-blaCMY-2-blc-sugE and only one isolate with tnpA-blaCMY-2. Transformation of these plasmids into E. coli pir116 produced multidrug resistance. Furthermore, PCR-RFLP analysis determined 5 different plasmid profiles and identical RFLP pattern between S. Typhimurium and S. sonnei. Transformation of the recombinant plasmids into E. coli and different Salmonella serovars resulted in phenotypes ranging from susceptible to resistant (especially inducible resistance) to CRO that were dependent on the genes, and host. CONCLUSION: The CRO susceptibility associated with the ISEcp-1 tnpA-blaCMY-2-blc-sugE element is regulated positively by ISEcp-1 tnpA and SugE and negatively regulated by Blc and unknown species-dependent host factor(s).

Whole-genome characterisation of TEM-1 and CMY-2 ß-lactamase-producing Salmonella Kentucky ST198 in Lebanese broiler chain.

OBJECTIVES: Salmonella enterica subsp. enterica serovar Kentucky has been associated with the worldwide ciprofloxacin-resistant (CIPR) Salmonella Kentucky sequence type 198 (ST198) epidemic clone, mostly recovered from poultry farms and products. The aim of this study was to examine whether this expanding clone exists in the Lebanese broiler chain. METHODS: Eight CIPR and extended-spectrum cephalosporin-resistant Salmonella Kentucky isolates previously recovered from Lebanese broilers were genetically characterised by whole-genome sequencing. RESULTS: Seven of the eight isolates belonged to ST198 and were phylogenetically closely related. They all harboured mutations in the chromosomal quinolone resistance genesgyrA and parC with double and single substitutions, respectively. The blaTEM-1B and blaCMY-2 genes were both detected in six isolates. Insertion sequence ISEcp1 was located upstream of blaCMY-2, harboured by IncI1 plasmids in four strains. An IS10 transposition coupled to homologous recombination at transposition sites mediated CMY-2 plasmid integration into the chromosome of one strain. Resistance genes to aminoglycosides [aadA7 and aac(3)-Id], tetracyclines [tet(A)] and sulfonamides (sul1) were detected in five strains, among which four were positive for the presence of Salmonella genomic island 1 (SGI1) variant SGI1-K. All studied isolates harboured a variety of Salmonella pathogenicity islands (SPIs) as well as common regulatory and virulence genes. CONCLUSION: Here we report for the first time in Lebanon the detection and dissemination of the emerging highly drug-resistantSalmonella Kentucky ST198. Our findings shed new light on this clone as a potential public-health threat.

Short communication: Whole-genome sequence analysis of 4 fecal blaCMY-2-producing Escherichia coli isolates from Holstein dairy calves.

This study was carried out to determine the antimicrobial resistance (AMR) genes and mobile genetic elements of 4 fecal blaCMY-2-producing Escherichia coli isolated from Holstein dairy calves on the same farm using whole-genome sequencing. Genomic analysis revealed that 3 of the 4 isolates shared similar genetic features, including sequence type (ST), serotype, plasmid characteristics, insertion ST, and virulence genes. In addition to genes encoding for complex multidrug resistance efflux systems, all 4 isolates were carriers of genes conferring resistance to ß-lactams (blaCMY-2, blaTEM-1B), tetracyclines (tetA, tetB, tetD), aminoglycosides [aadA1, aph(3")-lb, aph(6)-ld], sulfonamides (sul2), and trimethoprim (dfrA1). We also detected 4 incompatibility plasmid groups: Inc.F, Inc.N, Inc.I, and Inc.Q. A novel ST showing a new purA and mdh allelic combination was found. The 4 isolates were likely enterotoxigenic pathotypes of E. coli, based on serotype and presence of the plasmid Inc.FII(pCoo). This study provides information for comparative genomic analysis of AMR genes and mobile genetic elements. This analysis could give some explanation to the multidrug resistance characteristics of bacteria colonizing the intestinal tract of dairy calves in the first few weeks of life.

An emerging threat of ceftriaxone-resistant non-typhoidal salmonella in South India: Incidence and molecular profile.

Background: Non-typhoidal Salmonella (NTS) infection is a serious public health problem globally. Although NTS infections are self-limited, antimicrobial therapy is recommended for severe infections and immunocompromised patients. Antimicrobial resistance (AMR) in these pathogens further limits its therapeutic options. Here, we report an incidence of ceftriaxone resistance in NTS over the past 9 years in a southern Indian region. Materials and Methods: Molecular mechanisms of resistance in ceftriaxone-resistant NTS have been tested by both phenotypic and molecular methods. Minimum inhibitory concentration was determined by the E-test and broth microdilution method. AMR gene markers of ß-lactamases such as AmpCs (blaMOX, blaCMY, blaDHA, blaFOX, blaACC and blaACT) and extended-spectrum ß-lactamases (ESBLs) (blaSHV, blaTEM, blaVEB, blaPER, blaCTXM-1like,blaCTXM-2like, blaCTXM-8like, blaCTXM-9like and blaCTXM-25like) were screened. The presence of IncH12 and IncI1 plasmid was also analysed. Results: The study reports a 5% prevalence of ceftriaxone resistance in NTS. The most common serogroup was Salmonella Group B followed by Salmonella Group E and Salmonella group C1/C2. The occurrence of blaCTX-M-1, blaTEM, blaCMY and blaSHV genes was observed in 54%, 54%, 48% and 3% of the isolates, respectively. Interestingly, few isolates carried dual resistance genes (ESBLs and AmpCs). IncH12 and IncI1 plasmid was identified in isolates carrying ESBL and AmpC genes, respectively. Conclusion: This study shows that ceftriaxone resistance is mainly mediated by ß-lactamases such as ESBL and AmpC. As the incidence of ceftriaxone resistance is rising gradually over the years, it is imperative to monitor the AMR in this species.

blaNDM-1-producing Vibrio parahaemolyticus and V. vulnificus isolated from recreational beaches in Lagos, Nigeria.

Twenty-six strains of Vibrio parahaemolyticus and 14 strains of V. vulnificus isolated from selected beaches in Lagos State, Nigeria, were examined for virulence and antimicrobial resistance genes. The V. parahaemolyticus isolates were further serotyped and subjected to pulsed field gel electrophoresis (PFGE). Five strains of V. vulnificus and one of V. parahaemolyticus carried the New Delhi-metallo-beta-lactamase gene blaNDM-1, seven strains carried blaTEM, and four strains of V. vulnificus and one of V. parahaemolyticus carried blaCMY. Real-time PCR assay for detection of virulence genes tdh and trh in the V. parahaemolyticus isolates showed that five isolates were positive for tdh, two for trh, and one isolate carried both genes. Ten V. parahaemolyticus serogroups and 23 pulsotypes were identified from 26 isolates based on O and K antigens typing and PFGE. Five of the isolates belong to the pandemic strains O1:Kut and O3:K6, and three belonged to the highly virulent O4:Kut serotype. Nineteen of the isolates showed distinct PFGE banding patterns. These results highlighted the importance of Nigerian recreational beaches as reservoirs of antimicrobial resistance genes of global public health interest, such as blaNDM-1.

A culture-independent method for studying transfer of IncI1 plasmids from wild-type Escherichia coli in complex microbial communities.

IncI1 plasmids play a central role in the transfer of antimicrobial resistance genes among Enterobacteriaceae in animals and humans. Knowledge on the dynamics of IncI1 plasmid transfer is limited, mainly due to lack of culture-independent methods that can quantify donor strain survival and plasmid transfer in complex microbial communities. The aim of this study was to develop a culture-independent method to study the dynamics of IncI1 plasmids transfer by fluorescence-activated cell sorting. We genetically modified three wild-type Escherichia coli of animal (n = 2) and human (n = 1) origin carrying blaCMY-2 or blaCTX-M-1 on two epidemic IncI1 plasmids (pST12 and pST7). Non-coding regions on the chromosome and on the IncI1 plasmid of each strain were tagged with mCherry (red) and GFPmut3 (green) fluorescent proteins, respectively, using lambda recombineering. A gene cassette expressing mCherry and lacIq was inserted into the chromosome, whereas the plasmid was marked with a GFPmut3 cassette with LacIq repressible promoter. Therefore, gfpmut3 was repressed in donor strains but expressed in recipient strains acquiring the plasmids. We demonstrated that genetic engineering of the strains did not affect the growth rate and plasmid transfer-ability in filter and broth matings. A proof-of-concept experiment using the CoMiniGut, an in vitro model of the colon, proved the validity of our method for studying the survival of wild-type E. coli and horizontal transfer of IncI1 plasmids under different pH and oxygen conditions. The dual-labeling method by fluorescent proteins is useful to determine persistence of exogenous E. coli and transfer dynamics of IncI1 plasmids in microbial communities.

Draft genome sequence of a blaCMY-2/IncI1-harbouring Escherichia coli D:ST457 isolated from coastal benthic organisms.

OBJECTIVES: Marine bivalves can act as bioindicators of marine environment pollution by multidrug-resistant (MDR) enteric bacteria of medical interest. The aim of this study was to report the draft genome sequence of a plasmid-encoded AmpC (pAmpC) (CMY-2)-carrying Escherichia coli isolate recovered from a marine bivalve sample in the coastal shore of Southeast Brazil. METHODS: The whole genome was sequenced on an Illumina NextSeq platform and was assembled using Velvet v.1.2.10. Data analysis was carried out using tools available from the Center of Genomic Epidemiology and Geneious R10 software. RESULTS: The genome size was calculated at 5198055bp, comprising a total of 5316 protein-coding sequences. The strain was assigned to ST457 and presented the blaCMY-2 pAmpC gene. In addition, the strain was clustered into the pathogenic phylogenetic group D. CONCLUSION: The release of this draft genome sequence can provide valuable information to better understand the dissemination of MDR enteric bacteria in marine environments.

Occurrence of blaCMY-42 on an IncI1 plasmid in multidrug-resistant Escherichia coli from a tertiary referral hospital in India.

OBJECTIVES: Plasmids of different replicon types are believed to be associated with the carriage and transmission of antimicrobial resistance genes. The present study was undertaken to examine the association of blaCIT with particular plasmid types and to identify Escherichia coli strains involve in the maintenance of this resistance determinant in the plasmid. METHODS: Phenotypic screening of AmpC ß-lactamases was performed by the modified three-dimensional extract method, followed by antimicrobial susceptibility testing and determination of minimum inhibitory concentrations (MICs). Genotyping screening of ß-lactamase genes was performed by PCR assay, followed by sequencing. Transferability of the blaCMY gene was performed by transformation and conjugation experiments. Plasmid incompatibility typing and DNA fingerprinting by enterobacterial repetitive intergenic consensus (ERIC)-PCR were performed. RESULTS: Among 203 E. coli obtained from different clinical specimens (pus, urine, stool and sputum), 37 were detected as harbouring the blaCIT gene and sequencing of this gene showed nucleotide sequence similarity with the blaCMY-42 variant. This study revealed IncI1-type plasmids as carriers of blaCMY-42 and its propagation within E. coli ST5377, ST361 and ST672. According to the stability results, the blaCMY-42-encoding plasmid can be maintained in E. coli strains for a longer duration without any antimicrobial pressure. CONCLUSIONS: These finding document blaCMY-42 on IncI1-type plasmids, which are considered to be the main vehicles for the spread of blaCMY-42 in this hospital setting. Thus, a proper strategy should be developed to curb the expansion of IncI1-type plasmids in the hospital and community environment.

Imported poultry meat as a source of extended-spectrum cephalosporin-resistant CMY-2-producing Salmonella Heidelberg and Salmonella Minnesota in the European Union, 2014-2015.

Extended-spectrum cephalosporin (ESC)-resistant Salmonella have been described at a low level in the EU, nevertheless the increasing importation of poultry meat could be an important source of epidemic strains carrying ESC resistance genes. This study evaluated ESC resistance and its genetic platform among Salmonella isolates from poultry meat products imported into Portugal as well as clonal relatedness of the isolates. All Salmonella isolates recovered from samples of fresh meat destined for import into the EU in the scope of Portuguese official border control (2014-2015) were studied. Antibiotic susceptibility and ß-lactamase production was determined by disk diffusion/microdilution. Molecular studies included detection of genes encoding acquired AmpC and extended-spectrum ß-lactamases, plasmid-mediated quinolone resistance and other antibiotic resistance genes by PCR/sequencing, and clonality by MLST and XbaI-PFGE. Plasmid characterisation was assessed by conjugation assays, replicon typing (PCR-PBRT/pMLST) and hybridisation experiments (I-CeuI/S1-PFGE nuclease). Isolates belonged to Salmonella Heidelberg (n = 6; ST15/eBG26) and Salmonella Minnesota (n = 1; ST548/eBG77) and presented multidrug-resistant profiles, including to ESCs and/or fluoroquinolones. All but one carried blaCMY-2, located on two epidemic plasmids, IncA/C (ST2, n = 5) or transferable IncI1 (ST12, n = 1). Salmonella Heidelberg was associated with five PFGE types, including one similar to an American epidemic clone. This study reveals imported poultry products as a source of uncommon and/or invasive ESC-resistant Salmonella strains in the EU. The increase of clinically relevant poultry-related serotypes in Europe must be taken into account in the current monitoring of antibiotic resistance trends and in re-evaluation of food regulations.

Phenotypic and genotypic profile of clinical and animal multidrug-resistant Salmonella enterica isolates from Mexico.

AIMS: The objective of this study was to obtain a phenotypic and genotypic profile of Salmonella enterica including multidrug-resistant (MDR) isolates from food-producing animals and clinical isolates, as well as their genetic relatedness in two different States of Mexico (Jalisco and State of Mexico). METHODS AND RESULTS: A total of 243 isolates were evaluated in terms of antimicrobial resistance (AMR) and related genes through a disk diffusion method and PCR respectively; we found 16 MDR isolates, all of them harbouring the blaCMY gene but not qnr genes, these isolates represent less than 10% of the collection. The pulsed-field gel electrophoresis revealed a higher genotypic similitude within isolates of State of Mexico than Jalisco. CONCLUSIONS: A low percentage of Salmonella isolates were resistant to relevant antibiotics in human health, nevertheless, the AMR and involved genes were similar despite the different serovars and origin of the isolates. SIGNIFICANCE AND IMPACT OF THE STUDY: This investigation provided an insight of the current status of AMR of Salmonella isolates in two States of Mexico and pinpoint the genes involved in AMR and their epidemiological relationship, the information could help to determine an adequate therapy in human and veterinary medicine.

Convergence of plasmid architectures drives emergence of multi-drug resistance in a clonally diverse Escherichia coli population from a veterinary clinical care setting.

The purpose of this study was to determine the plasmid architecture and context of resistance genes in multi-drug resistant (MDR) Escherichia coli strains isolated from urinary tract infections in dogs. Illumina and single-molecule real-time (SMRT) sequencing were applied to assemble the complete genomes of E. coli strains associated with clinical urinary tract infections, which were either phenotypically MDR or drug susceptible. This revealed that multiple distinct families of plasmids were associated with building an MDR phenotype. Plasmid-mediated AmpC (CMY-2) beta-lactamase resistance was associated with a clonal group of IncI1 plasmids that has remained stable in isolates collected up to a decade apart. Other plasmids, in particular those with an IncF replicon type, contained other resistance gene markers, so that the emergence of these MDR strains was driven by the accumulation of multiple plasmids, up to 5 replicons in specific cases. This study indicates that vulnerable patients, often with complex clinical histories provide a setting leading to the emergence of MDR E. coli strains in clonally distinct commensal backgrounds. While it is known that horizontally-transferred resistance supplements uropathogenic strains of E. coli such as ST131, our study demonstrates that the selection of an MDR phenotype in commensal E. coli strains can result in opportunistic infections in vulnerable patient populations. These strains provide a reservoir for the onward transfer of resistance alleles into more typically pathogenic strains and provide opportunities for the coalition of resistance and virulence determinants on plasmids as evidenced by the IncF replicons characterised in this study.

Fortuitous Detection of cmy-2 and dha-1 from ESBL-producing Escherichia coli in Senegal.

Cephalosporinases, which are naturally present in some enterobacterial species, can be mobilized by transposons, migrate to plasmids, and spread into other species such as Escherichia coli. The aim of this study was to characterize genes responsible for the production of extended-spectrum ß-lactamases (ESBL) in E. coli isolates from urinary origin isolated in two hospitals in Senegal. Thus, a fortuitous discovery of plasmidic cephalosporinase in two isolates was noted. One of the isolates produced dha-1 associated with ESBL CTX-M-14, the other produced cmy-2, ESBL CTXM-15, tem-1 penicillinase, and oxa-1. This confirms the circulation of multidrug-resistant bacteria producing plasmidic cephalosporinase in Senegal. However, a large study is needed to better understand the prevalence and the nature of the genes involved.