Extended-spectrum-beta-lactamase (TEM-52)-producing strains of Salmonella enterica of various serotypes isolated in France

Whole genome sequencing based prediction of antimicrobial resistance evolution among the predominant bacterial pathogens of diabetic foot ulcer

Emerging antibiotic resistance among bacterial pathogens of diabetic foot ulcers (DFUs) cause a significant threat to the human health. In the study, deep ulcer swabs were collected from 70 diabetic patients with foot ulcer. Among the 187 bacterial strains purified from the same, major representations were identified to be from Klebsiella pneumoniae and Staphylococcus spp. Here, polymicrobial infection (87.14%) was found to be more prevalent than monomicrobial (12.86%). From the antibiotic susceptibility test results, 34 bacterial isolates were identified as MDR pathogens with resistance to β-lactam and carbapenem classes of antibiotics. Furthermore, molecular screening has revealed the presence of antibiotic resistance gene such as blaSHV,blaCTX-M, blaTEM,blaOXA-48, NDM-1, mecA and blaZ genes among the isolates studied. Biofilm analysis has further revealed 31 strains to have strong and 3 with moderate biofilm production property. Among the MDR strains, K. pneumoniae (DFU2.2) and methicillin-resistant S. aureus (MRSA) (DFU24.3) were subjected to the whole-genome sequencing (WGS) based analysis due to their significant role in the chronicity of DFUs. The resistome prediction from the WGS data of DFU2.2 has revealed it to have the presence of a novel extended β-lactamase gene blaSHV-106 which has not been reported previously from India. Pan-genome analysis of DFU2.2 and DFU24.3 has also provided detailed insight into the genetic diversity, evolution, and pathogenic potential of the selected strains. The findings of this study hence suggest the emerging AMR to be one of the major risk factors challenging the therapeutic response of DFUs, the incidence of which is alarmingly high.

Incidence, identification and antibiotic resistance of Salmonella spp. in the well waters of Tadla Plain, Morocco

Concerns about challenges with water availability in the Tadla Plain region of Morocco have grown as a result of groundwater contamination brought on by human activity, climate change, and insufficient groundwater management. The objective of the study is to measure the number of resistant bacteria in the groundwater of Beni Moussa and Beni Aamir, as well as to evaluate the level of water pollution in this area. 200 samples were therefore gathered from 43 wells over the course of four seasonal campaigns in 2017 and 2018. Additionally, the samples were examined to determine whether Salmonella species were present and if they were resistant to the 16 antibiotics that were tested. Salmonella spp. have been identified in 31 isolated strains in total, accounting for 18.02% of all isolated strains. Data on antibiotic resistance show that 58.1% of Salmonella spp. strains are multidrug-resistant (MDR); 38.7% of Salmonella strains are tolerant to at least six antibiotics, 19.4% to at least nine antibiotics, 9.7% to four to seven antibiotics, 6.5% to at least eleven antibiotics, and the remaining 3.2% to up to twelve antibiotics. A considerable level of resistance to cefepime (61.29%), imipenem (54.84%), ceftazidime (45.16%), ofloxacin (70.97%), and ertapenem (74.19%) was found in the data. Consequently, it is important to monitor and regulate the growth of MDR in order to prevent the groundwater's quality from declining.

Therapeutic Switching of Rafoxanide: a New Approach To Fighting Drug-Resistant Bacteria and Fungi

Control and management of life-threatening bacterial and fungal infections are a global health challenge. Despite advances in antimicrobial therapies, treatment failures for resistant bacterial and fungal infections continue to increase. We aimed to repurpose the anthelmintic drug rafoxanide for use with existing therapeutic drugs to increase the possibility of better managing infection and decrease treatment failures. For this purpose, we evaluated the antibacterial and antifungal potential of rafoxanide. Notably, 70% (70/100) of bacterial isolates showed multidrug resistance (MDR) patterns, with higher prevalence among human isolates (73.5% [50/68]) than animal ones (62.5% [20/32]). Moreover, 22 fungal isolates (88%) were MDR and were more prevalent among animal (88.9%) than human (87.5%) sources. We observed alarming MDR patterns among bacterial isolates, i.e., Klebsiella pneumoniae (75% [30/40; 8 animal and 22 human]) and Escherichia coli (66% [40/60; 12 animal and 28 human]), and fungal isolates, i.e., Candida albicans (86.7% [13/15; 4 animal and 9 human]) and Aspergillus fumigatus (90% [9/10; 4 animal and 5 human]), that were resistant to at least one agent in three or more different antimicrobial classes. Rafoxanide had antibacterial and antifungal activities, with minimal inhibitory concentration (MICs) ranging from 2 to 128 μg/mL. Rafoxanide at sub-MICs downregulated the mRNA expression of resistance genes, including E. coli and K. pneumoniae blaCTX-M-1, blaTEM-1, blaSHV, MOX, and DHA, C. albicans ERG11, and A. fumigatus cyp51A. We noted the improvement in the activity of β-lactam and antifungal drugs upon combination with rafoxanide. This was apparent in the reduction in the MICs of cefotaxime and fluconazole when these drugs were combined with sub-MIC levels of rafoxanide. There was obvious synergism between rafoxanide and cefotaxime against all E. coli and K. pneumoniae isolates (fractional inhibitory concentration index [FICI] values ≤ 0.5). Accordingly, there was a shift in the patterns of resistance of 16.7% of E. coli and 22.5% of K. pneumoniae isolates to cefotaxime and those of 63.2% of C. albicans and A. fumigatus isolates to fluconazole when the isolates were treated with sub-MICs of rafoxanide. These results were confirmed by in silico and mouse protection assays. Based on the in silico study, one possible explanation for how rafoxanide reduced bacterial resistance is through its inhibitory effects on bacterial and fungal histidine kinase enzymes. In short, rafoxanide exhibited promising results in overcoming bacterial and fungal drug resistance. IMPORTANCE The drug repurposing strategy is an alternative approach to reducing drug development timelines with low cost, especially during outbreaks of disease caused by drug-resistant pathogens. Rafoxanide can disrupt the abilities of bacterial and fungal cells to adapt to stress conditions. The coadministration of antibiotics with rafoxanide can prevent the failure of treatment of both resistant bacteria and fungi, as the resistant pathogens could be made sensitive upon treatment with rafoxanide. From our findings, we anticipate that pharmaceutical companies will be able to utilize new combinations against resistant pathogens.

Plasmid Composition, Antimicrobial Resistance and Virulence Genes Profiles of Ciprofloxacin- and Third-Generation Cephalosporin-Resistant Foodborne Salmonella enterica Isolates from Russia

Salmonella enterica is an important foodborne pathogen worldwide. Ciprofloxacin and extended-spectrum cephalosporins are the common first-line antimicrobial drugs for the treatment of salmonellosis, antimicrobial resistance genes for which are mostly transferred via plasmids. The goal of this work was to perform genomic analysis of plasmids from foodborne S. enterica isolates obtained in Russia based on whole-genome sequencing. In the current study, 11 multidrug-resistant samples isolated in 2021 from 8 regions of Russia were selected based on their resistance to ciprofloxacin and third-generation cephalosporins (CIP-3rd). Whole-genome short-read sequencing (WGS) was performed for all isolates; the samples belonged to five different sequence types (ST32, ST469, ST11, ST142, and ST548) which had different profiles of antimicrobial resistance (AMR) and virulence genes. We have performed additional long-read sequencing of four representative S. enterica isolates, which showed that they carried pESI-like megaplasmids of 202-280 kb length harboring extended-spectrum β-lactamase genes, fluoroquinolone, tetracycline, and aminoglycosides resistance genes, as well as several virulence determinants. We believe that the WGS data obtained will greatly facilitate further studies of foodborne S. enterica isolates epidemiology in terms of their self-transmissible plasmid composition that mediated antimicrobial resistance and virulence determinants conferring selective advantages of this important bacterial pathogen.

Cefixime and cefixime-clavulanate for screening and confirmation of extended-spectrum beta-lactamases in Escherichia coli

Introduction

Detection of Extended-Spectrum Beta-Lactamases (ESBLs) depends on screening for resistance to certain cephalosporins, confirmation with selective ESBL inhibitors, and ESBL genes detection. New tests are required for accurate ESBL detection.

Aims

To test the ability of cefixime (CFM) and cefixime-amoxicillin/clavulanate (CFM-AMC) as a screening and confirmatory test for ESBL identification.

Methods

246 clinical isolates of Escherichia coli were tested by an ESBL screening test, a double-disk synergy test (DDST), a disk replacement test, the Vitek 2 ESBL test, and an ESBL genes test by PCR. CFM ESBL Screening was performed by disk diffusion, while CFM-AMC confirmation was performed by DDST and a disk replacement test.

Results

246 E. coli clinical isolates from two referral hospitals were collected over 2 years. The mean age ± standard deviation of patients was 43.8 ± 27.7 years and 76.8% were females. Resistance rates to penicillins, first, second, and third generation cephalosporins, and monobactams were very high at 97%, 84%, 100% and 97%, respectively. ESBL screening was positive in 81.3% of isolates, DDST was positive in 74.8%, disk replacement was positive in 79%, Vitek 2 ESBL test was positive in 67.3%, and ESBL genes were detected in 85.8% of isolates (CTX-M 75%, TEM 42.5%, SHV 4.6%). Compared to genotyping, screening with CFM achieved 87.7% sensitivity and 64.7% specificity. CFM-AMC DDST achieved 75.8% sensitivity and 75.4% specificity, and CFM-AMC disk replacement had 73% sensitivity and 70% specificity.

Conclusions

High prevalence of ESBLs was noted among E. coli isolates, dominated by CTX-M genotype. ESBL screening and confirmation using CFM and CFM-AMC is a new and accurate method for ESBLs detection.

Antimicrobial Susceptibility and Detection of Virulence-Associated Genes in Escherichia coli Strains Isolated from Commercial Broilers

The aim of this study was to investigate the presence of iron-uptake and virulence genes, antibiotic resistance profiles, and phylogenetic relatedness in 115 Escherichia coli (E. coli) strains isolated from broilers in Slovakia and to determine their potential threat to human health. The most frequent phylogroups were B1 (37%) and A (21%), and 33.9% strains were included in pathogenic groups. The commonly observed iron-uptake genes were feoB (94%), sitA (83%), and iutA (58%). Protectins (iss, kpsMTII) were identified in 30% of samples. Four percent of B2-associated broilers carried the papC (P fimbria) gene connected with upper urinary tract infection. The dominant resistance was to tetracycline (49%), ampicillin (66%), ampicillin + sulbactam (27%), ciprofloxacin (61%), and trimethoprim + sulfonamide (34%); moreover, sporadically occurring resistance to cephalosporins, aminoglycosides, fluoroquinolones, and polypeptide colistin was observed. Genotypic analysis of resistance revealed the presence of bla_CTX-M-1 and bla_CTX-M-2 in two isolates from broilers. Commercial broilers can be reservoirs of virulent and resistant genes as well as E. coli causing (extra-)intestinal infections, which can be a potential threat to humans via direct contact and food.

New Insight on Antibiotic Resistance and Virulence of Escherichia coli from Municipal and Animal Wastewater

Antibiotic resistance of the indicator microorganism Escherichia coli was investigated in isolates from samples collected during the course of one year from two wastewater treatment plants treating municipal and animal wastes in Slovakia, respectively. The genes of antibiotic resistance and virulence factors in selected resistant E. coli isolates were described. A high percentage of the isolates from municipal and animal wastewater were resistant to ampicillin, streptomycin, tetracycline, ceftiofur, ceftriaxone, and enrofloxacin. In the selected E. coli isolates, we detected the following phenotypes: ESBL (20.4% in animal wastewater; 7.7% in municipal wastewater), multidrug-resistant (17% of animal and 32% of municipal isolates), high resistance to quinolones (25% of animal and 48% of municipal samples), and CTX-M (7.9% of animal and 17.3% of municipal isolates). We confirmed an integro-mediated antibiotic resistance in 13 E. coli strains from municipal and animal wastewater samples, of which the Tn3 gene and virulence genes cvaC, iutA, iss, ibeA, kps, and papC were detected in six isolates. One of the strains of pathogenic E. coli from the animal wastewater contained genes ibeA with papC, iss, kpsII, Int1, Tn3, and Cit. In addition, one bla_IMP gene was found in the municipal wastewater sample. This emphasises the importance of using the appropriate treatment methods to reduce the counts of antibiotic-resistant microorganisms in wastewater effluent.

Antimicrobial Resistance Patterns and Risk Factors Associated with Salmonella spp. Isolates from Poultry Farms in the East Coast of Peninsular Malaysia: A Cross-Sectional Study

The burden of antimicrobial use in agricultural settings is one of the greatest challenges facing global health and food security in the modern era. Malaysian poultry operations are a relevant but understudied component of epidemiology of antimicrobial resistance. We aimed to identify the prevalence, resistance patterns, and risk factors associated with Salmonella isolates from poultry farms in three states of East Coast Peninsular Malaysia. Between 8 February 2019 and 23 February 2020, a total of 371 samples (cloacal swabs = 259; faecal = 84; Sewage = 14, Tap water = 14) was collected from poultry operations. Characteristics of the sampled farms and associated risk factors were obtained using semi-structured questionnaires. Presumptive Salmonella spp. isolates were identified based on colony morphology with subsequent biochemical and PCR confirmation. Susceptibility of isolates was tested against a panel of 12 antimicrobials using disk diffusion method. Our findings revealed that the proportion of Salmonella spp.-positive isolates across sample source were as following: cloacal swab (46.3%, 120/259); faecal (59.5%, 50/84); in tap water (14.3%, 2/14); and in sewage sample (35.7%, 5/14). Isolates from faecal (15.5%, 13/84), cloacal (1.2%, 3/259), and sewage (7.1%, 1/14) samples were significantly resistant to at least five classes of antimicrobials. Resistance to Sulfonamides class (52%, 92/177) was predominantly observed followed by tetracycline (39.5%, 70/177) and aminoglycosides (35.6%, 63/177). Multivariate regression analysis identified intensive management system (OR = 1.55, 95% CI = 1.00–2.40) as a leading driver of antimicrobial resistance (AMR) acquisition. A prevalence of resistance to common antimicrobials was recorded for sulfamethoxazole (33.9%), tetracycline (39.5%), and trimethoprim-sulphamethoxazole (37.9%). A close association between different risk factors and the prevalence of AMR of Salmonella strains suggests a concern over rising misuse of veterinary antimicrobials that may contribute to the emergence and evolution of multidrug-resistant pathogen isolates. One Health approach is recommended to achieve a positive health outcome for all species.

Antibiotic Resistant and Biofilm-Associated Escherichia coli Isolates from Diarrheic and Healthy Dogs

Bacteria isolated from companion animals are attracting concerns in a view of public health including antimicrobial resistance and biofilm development, both contributing to difficult-to-treat infections. The purpose of this study was to evaluate the minimum inhibitory concentrations (MIC) of 18 antibiotics in Escherichia coli isolated from two groups of dogs (healthy and diarrheic). Isolates were classified into phylogroups, examined for the presence of resistance genes and biofilm-formation capacity. In healthy dogs, phylogenetic analysis showed that 47.37% and 34.22% of E. coli isolates belonged to commensal groups (A; B1) in contrast to diarrheic dogs; 42.2% of isolates were identified as the B2 phylogroup, and these E. coli bacteria formed a stronger biofilm. The results of healthy dogs showed higher MIC levels for tetracycline (32 mg/L), ampicillin (64 mg/L), ciprofloxacin (8 mg/L) and trimethoprim-sulphonamide (8 mg/L) compared to clinical breakpoints. The most detected gene encoding plasmid-mediated resistance to quinolones in the healthy group was qnrB, and in dogs with diarrhea, qnrS. The resistance genes were more frequently detected in healthy dogs. The presence of the integron int1 and the transposon tn3 increases the possibility of transfer of many different cassette-associated antibiotic-resistance genes. These results suggest that dogs could be a potential reservoir of resistance genes.

Antibiotic resistance and virulence of Escherichia coli strains isolated from animal rendering plant

Processing of animal carcasses and other animal wastes in rendering plants is a significant source of antibiotic resistant microorganisms. The main goal of this study was to investigate the resistance to 18 antibacterial agents including β-lactams, fluoroquinolones, colistin and virulence factors (iss, tsh, cvaC, iutA, papC, kps and ibeA genes) in 88 Escherichia coli strains isolated from a rendering plant over 1 year period. ESBL (Extended-spectrum beta-lactamases) and plasmid-mediated Amp were screened by interpretative reading of MIC. ESBL phenotype was detected in 20.4% of samples and high level of resistance to fluoroquinolone was found in 27.2% of strains. Cephalosporinase CTX-M1, cephamycinase CMY-2, integrase 1 and transposon 3 genes were detected by PCR. Furthermore, there were found three CMY-2 producing E. coli with O25b-ST131, resistant to the high level of enrofloxacin and containing the gene encoding the ferric aerobactin receptor (iutA). One enrofloxacin resistant E. coli strain possessed iss, ibeA, kps and papC virulence genes also with CMY-2, integrase1 and Tn3. ST131 E. coli with CMY-2 has a zoonotic potential and presents a serious health risk to humans.

Antibiotic resistance and virulence factors of Escherichia coli from eagles and goshawks

One of the major global problems in medicine is microbial resistance to antibiotics (antimicrobial resistance) and this has become an increasingly frequent research topic. This study focuses on antimicrobial resistance, phylogenetic and genetic characterization of Escherichia coli from wild birds: ten isolates from eagles (Aquila chrysaetos), nine from goshawks (Accipiter gentilis) and 24 from broilers in the Slovak Republic. Twenty-two strains with presence of int1 gene were selected and examined for the presence or absence of transposon gene (tn3), genes of antibiotic resistance and virulence factors. We detected sequence type (ST) in eagles ST 442 with genes iss, papC, iutA, cvaC, tsh, fyuA, iroN, kps, feoB, sitA, irp2, ireA for virulence factors and tetA, sul1, sul2, dfrA, aadA for antibiotic resistance; in goshawks ST 1011 with iss, papC, fyuA, iroN, feoB, sitA and qnrS1, tetA, sul1, sul2, dfrA, aadA, respectively. These ST types have been found in humans too and should be evaluated further for possible zoonotic potential and transfer of resistance genes from the environment.

Decrease in the prevalence of extended-spectrum cephalosporin-resistant Salmonella following cessation of ceftiofur use by the Japanese poultry industry

Extended-spectrum cephalosporin (ESC)-resistant Salmonella in chicken meat is a significant food safety concern. We previously reported that the prevalence of ESC-resistant Salmonella in chicken meat, giblets, and processed chicken (chicken meat products) increased in Japan between 2005 and 2010, with 27.9% (17/61) of Salmonella isolated from chicken meat products in 2010 showing resistance to ESC. The aims of the present study were to clarify trends in the prevalence of ESC-resistant Salmonella in chicken meat products in Japan between 2011 and 2015, and to determine the genetic profiles of bla-harboring plasmids, including replicon types, using next-generation sequencing. Our results showed that the prevalence of ESC-resistant Salmonella, mainly consisting of AmpC β-lactamase CMY-2-producing isolates, in chicken meat products had increased to 45.5% (10/22) by 2011. However, following the voluntary cessation of ceftiofur use by the Japanese poultry industry in 2012, the prevalence of ESC-resistant Salmonella steadily decreased each year, to 29.2% (7/24), 18.2% (4/22), 10.5% (2/19), and 10.5% (2/19) in 2012, 2013, 2014, and 2015, respectively. Furthermore, no AmpC β-lactamase CMY-2-producing isolates were identified in 2014 and 2015. However, the prevalence of Salmonella enterica subspecies enterica serovar Manhattan isolates harboring a bla_TEM-52-carrying IncX1 plasmid remained steady even after the cessation of ceftiofur use. Therefore, continuous monitoring of ESC resistance amongst Salmonella isolates from chicken meat products is required for food safety.

Molecular signature of extended spectrum β-lactamase producing Klebsiella pneumoniae isolated from bovine milk in eastern and north-eastern India

The present study reports on 23 extended spectrum β-lactamase producing Klebsiella pneumoniae (KP), isolated from milk samples (n=340) of healthy cows (n=129) and cows with subclinical (n=159) and clinical (n=52) mastitis, from three different states of India viz. West Bengal, Jharkhand and Mizoram. Seven of them were AmpC type β-lactamase producers, as well. The ESBL producing KP were significantly (P=0.006, χ2=10.04, df=2) and more frequently detected in milk samples of mastitic cows than healthy ones. The β-lactamase genes - blaCTX-M, blaTEM and blaSHV were detected in 19, 8 and 3 isolates, respectively. In all but one CTX-M positive isolates, the genetic platform - ISEcp1-blaCTX-M-orf477 was detected. Ten of the isolates carried plasmid mediated quinolone resistance gene - qnrS and 1 isolate possessed qnrB. Again 11 of them were found to have sulfonamide resistance gene - sul1 and 12 possessed class I integron. Sequencing of the class 1 integron revealed the presence of dfrA12/dfrA17 and aadA2/aadA5 gene cassettes conferring resistance to trimethoprim and aminoglycosides, respectively. All the isolates, characterized by enterobacterial repetitive intergenic consensus (ERIC) PCR, yielded distinct fingerprinting profile. However, most of the isolates from Jharkhand were clustered along with two isolates each from West Bengal and Mizoram indicating their clonal relatedness even though isolated from geographically different areas. Isolation of ESBL producing KP from bovine milk samples implies its public health significance; as such pathogens may enter the human food chain causing severe health hazards.

Colonization of extended-spectrum-β-lactamase- and NDM-1-producing Enterobacteriaceae among pregnant women in the community in a low-income country: a potential reservoir for transmission of multiresistant Enterobacteriaceae to neonates

The spread of extended-spectrum-β-lactamase-producing Enterobacteriaceae (ESBL-PE) in low-income countries, where the burden of neonatal sepsis is high, may have a serious impact on neonatal mortality rates. Given the potential for mother-to-child transmission of multiresistant bacteria, this study investigated the ESBL-PE rectal colonization among pregnant women at delivery in the community in Madagascar and estimated a prevalence of 18.5% (95% confidence interval, 14.5% to 22.6%). One strain of Klebsiella pneumoniae isolated was also a New Delhi metallo-β-lactamase-1 (NDM-1) producer.

Chronological Change of Resistance to β-Lactams in Salmonella enterica serovar Infantis Isolated from Broilers in Japan

Epidemiologic surveillance study was conducted in southern Japan to determine the antimicrobial resistance phenotypes and characterize the β-lactamase genes and the plasmids harboring these genes in Salmonella enterica serovar Infantis (S. Infantis) isolates from broilers. Between January, 2007 and December, 2008, a total of 1,472 fecal samples were collected and examined at the Laboratory of Veterinary Public Health, Kagoshima University, Japan. In 93 (6.3%) isolates recovered, 33 (35.5%) isolates showed resistance to cefotaxime, an extended-spectrum cephalosporin (ESC), conferred by TEM-20, TEM-52 and CTX-M-25 extended-spectrum β-lactamases (ESBLs). In addition to ESC-resistance, eight (8.6%) isolates exhibited resistance to cefoxitin mediated by CMY-2 AmpC β-lactamase. Plasmid analysis and polymerase chain reaction replicon typing revealed the bla TEM-20 and bla CMY-2 genes were associated with IncP plasmids, bla TEM-52 was linked with a non-typable plasmid and bla CTX-M-25 was carried by an IncA/C plasmid. Non-β-lactam resistance to streptomycin, sulfamethoxazole, and oxytetracycline encoded by the aadA1, sul1, and tet(A) genes, respectively, was found in 86 (92.5%) isolates. Resistance to kanamycin and ofloxacin was exhibited in 12 (12.9%) and 11 (11.8%) isolates, respectively, the former was mediated by aphA1-Iab. These data indicate that S. Infantis isolates producing ESBLs and AmpC β-lactamase have spread among broiler farms in Japan. These data demonstrated that the incidence of ESC-resistant S. Infantis carrying bla TEM-52 remarkably increased and S. Infantis strains harboring bla CMY-2, bla TEM-20, or bla CTX-M-25 genes emerged from broilers in Japan for the first time in 2007 and 2008.

PCR-Based Detection of Extended-Spectrum β-Lactamases (bla CTX-M-1 and bla TEM ) in Escherichia coli, Salmonella spp. and Klebsiella pneumoniae Isolated from Pigs in North Eastern India (Mizoram)

Cephalosporins are major antimicrobials used to treat serious infections. However, their effectiveness is being compromised by the emergence of extended-spectrum β-lactamases (ESBLs). A total of 138 enteric bacteria were isolated from 53 faecal samples of pigs collected from different districts of Mizoram, of which 102 (73.91 %) were Escherichia coli, 26 (18.84 %) were Salmonella spp. and 10 (7.25 %) were Klebsiella pneumoniae. Phenotypic confirmatory test (Double Discs Synergy Test) showed that 8 (5.80 %) E. coli isolates were ESBLs producer. PCR analysis confirmed that out of the eight isolate, 7 (5.07 %) harboured bla CTX-M-1 gene and/or bla TEM gene. Of the eight positive isolates, 7 (5.07 %) and 3 (2.17 %) were found to be positive for bla CTX-M-1 gene and bla TEM gene, respectively, of which 3 (2.17 %) isolates were positive for both the genes. Only 4 (2.90 %) E. coli isolates carried bla CTX-M-1 gene alone. Agarose gel electrophoresis showed that all the isolates were carrying plasmids ranging between 0.9 and ~30 kb. Out of the seven isolates positive for bla CTX-M-1 and/or bla TEM , 2 (1.84 %) isolates were confirmed for bla CTX-M-1 gene in their plasmid. Only one E. coli isolate was found to be positive for both the genes in its plasmid. The resistance plasmid could not be transferred to a recipient by in vitro horizontal gene transfer method.

IncI1 plasmid carrying extended-spectrum-beta-lactamase gene blaCTX-M-1 in Salmonella enterica isolates from poultry and humans in France, 2003 to 2008

We report the dissemination of a conjugative IncI1 plasmid carrying bla(CTX-M-1), conferring resistance to extended-spectrum cephalosporins, in Salmonella enterica isolates from poultry and humans in France from 2003 to 2008. By IncI1 plasmid subtyping, this plasmid was shown to be genetically related to that found in Escherichia coli isolates from healthy poultry in France.

Antimicrobial resistance in nontyphoidal Salmonella

Salmonella is one of the leading causes of foodborne illness in countries around the world. Treatment of Salmonella infections, in both animals and humans has become more difficult with the emergence of multidrug-resistant (MDR) Salmonella strains. Foodborne infections and outbreaks with MDR Salmonella are also increasingly reported. To better monitor and control the spread of MDR Salmonella, it is important to understand the mechanisms responsible for drug resistance and how drug resistance is transmitted to and between Salmonella strains. This review summarizes current knowledge on antimicrobial drugs used to treat Salmonella infections and provides an overview of MDR Salmonella in the United States and a discussion of the genetics of Salmonella drug resistance, including the mechanisms responsible for the transmission of drug-resistance genes in Salmonella, using data from the United States and other countries.

Dissemination of an extended-spectrum-beta-lactamase blaTEM-52 gene-carrying IncI1 plasmid in various Salmonella enterica serovars isolated from poultry and humans in Belgium and France between 2001 and 2005

We report here the dissemination of a conjugative IncI1 plasmid carrying bla(TEM-52) on a Tn3 transposon conferring resistance to extended-spectrum cephalosporins in Salmonella enterica serovar Agona, Derby, Infantis, Paratyphi B dT(+), and Typhimurium isolates from poultry and humans in Belgium and France from 2001 to 2005. The most prevalent serovar spreading this resistance was serovar Infantis.

Salmonella enterica serovar Enteritidis producing a TEM-52 β-lactamase: first report in Spain

TEM-52 is an extended-spectrum beta-lactamase (ESBL) that is being increasingly reported in enterobacteria. In Spain, TEM-52 had been reported before only in Escherichia coli. Here we report the first finding of a TEM-52 ESBL in Salmonella in Spain, associated to a Tn3 transposon.

Multidrug resistance in Salmonella enterica serotype Typhimurium from humans in France (1993 to 2003)

The aim of this study was to determine the distribution of the antimicrobial resistance phenotypes (R types), the phage types and XbaI-pulsed-field gel electrophoresis (PFGE) types, the genes coding for resistance to beta-lactams and to quinolones, and the class 1 integrons among a representative sample of Salmonella enterica serotype Typhimurium isolates collected from humans in 2002 through the French National Reference Center for Salmonella (NRC-Salm) network. The trends in the evolution of antimicrobial resistance of serotype Typhimurium were reviewed by using NRC-Salm data from 1993, 1997, 2000, and 2003. In 2002, 3,998 isolates of serotype Typhimurium were registered at the NRC-Salm among 11,775 serotyped S. enterica isolates (34%). The most common multiple antibiotic resistance pattern was resistance to amoxicillin, chloramphenicol, streptomycin and spectinomycin, sulfonamides, and tetracycline (ACSSpSuTe R type), with 156 isolates (48.8%). One isolate resistant to extended-spectrum cephalosporins due to the production of TEM-52 extended-spectrum beta-lactamase was detected (0.3%), and one multidrug-resistant isolate was highly resistant to ciprofloxacin (MIC > 32 mg/liter). We found that 57.2% of the isolates tested belonged to the DT104 clone. The main resistance pattern of DT104 isolates was R type ACSSpSuTe (83.2%). However, evolutionary changes have occurred within DT104, involving both loss (variants of Salmonella genomic island 1) and acquisition of genes for drug resistance to trimethoprim or to quinolones. PFGE profile X1 was the most prevalent (74.5%) among DT104 isolates, indicating the need to use a more discriminatory subtyping method for such isolates. Global data from the NRC-Salm suggested that DT104 was the main cause of multidrug resistance in serotype Typhimurium from humans from at least 1997 to 2003, with a roughly stable prevalence during this period.

Salmonella resistant to extended-spectrum cephalosporins: prevalence and epidemiology

Salmonella resistant to extended-spectrum cephalosporins (ESCs) have emerged worldwide since 1988. By 2004, 43 countries had reported this public health problem. Resistance was mediated by classical extended-spectrum beta-lactamases, plasmid-mediated cephalosporinases, and recently a class A carbapenemase. Of these, CMY-2 is the most widely disseminated enzyme. Salmonella enterica serotype Typhimurium and S. enterica serotype Enteritidis are the most common serovars associated with ESC resistance in human infections. Many outbreaks in humans have been reported, most often among children and neonates. ESC-resistant Salmonella is frequently recovered from animals and food, with poultry as primary food source, suggesting that humans are often infected by these routes.

Serotype distribution and antimicrobial resistance of Salmonella enterica from patients with gastroenteritis in Crete, Greece

The aim of the present study was to determine the serotype distribution and the evolution of antimicrobial resistance among Salmonella enterica strains isolated from patients with diarrhea in Crete, Greece, during a 5-year period (2000-2004). Among the 401 S. enterica isolates recovered, serotype Enteritidis was the most prevalent (66.6%), followed by serotype Typhimurium (14.2%). The rates of resistance to ampicillin, amoxicillin-clavulanic acid, gentamicin, chloramphenicol, tetracycline, nalidixic acid and trimethoprim-sulfamethoxazole were 8.5, 7, 0.7, 5.4, 14.2, 2.7 and 2.7%, respectively. A marked decrease in resistance was observed during the study period. Resistance and multidrug resistance was most common in serotype Typhimurium. The extended-spectrum beta-lactamase production observed in one strain of S. enterica serotype Virchow and the reduced ciprofloxacin susceptibility detected in 2.7% of the isolates studied are causes of concern.

Resistance to Oxyiminocephalosporins Mediated byblaTEM-52Genes in Salmonella Typhimurium from Humans in England and Wales

The emergence of antimicrobial resistance among Salmonella is a matter of great public health concern, more so in the case of extended-spectrum cephalosporins, since these antimicrobials are normally regarded as the drugs of choice for complicated cases of infection. This study was designed to determine the occurrence of resistance mediated by the presence of extended-spectrum beta-lactamases (ESBL) enzymes belonging to the TEM family. Only two isolates were detected after analysis of the 278,308 Salmonella isolates from the last 10 years. In both cases, the gene involved was a bla (TEM-52)-like, and infections were linked with foreign travel. ESBL-TEM enzymes remain very rare in Salmonella in England and Wales, and no domestic cases have been detected to date.

Repeated occurrence of diverse extended-spectrum beta-lactamases in minor serotypes of food-borne Salmonella enterica subsp. enterica

Screening of Greek nontyphoid salmonellae from 2000 to 2002 yielded three extended-spectrum beta-lactamase (ESBL)-producing human isolates. Salmonella enterica serotype Brandenburg harbored a multiresistant SHV-5 gene-carrying plasmid. S. enterica serotype Blockley and S. enterica serotype Hadar harbored a TEM-52 gene-carrying plasmid. An S. enterica serotype Virchow strain producing plasmid-mediated CTX-M-32 was isolated twice from poultry end products. All ESBL plasmids were self-transferable and carried by clones currently common in Greece.

beta-Lactamases among extended-spectrum beta-lactamase (ESBL)-resistant Salmonella from poultry, poultry products and human patients in The Netherlands

OBJECTIVES

The purpose of this work was to study the genetic determinants responsible for extended-spectrum beta-lactamase (ESBL) resistance of Salmonella isolated from Dutch poultry, poultry meat and hospitalized humans.

METHODS

Thirty-four ESBL-resistant Salmonella isolates from The Netherlands were tested towards 21 antimicrobial agents. PCR and sequencing were used to determine the underlying genetic determinants responsible for the ESBL phenotypes. The transferability of the ESBL phenotypes was tested by conjugation to a susceptible Salmonella enterica serovar Dublin and plasmid purification, restriction fragment length polymorphism (RFLP) and pulsed-field gel electrophoresis (PFGE) were employed to further characterize a subset of the isolates.

RESULTS

A great genetic diversity was seen among the isolates. The bla(TEM-52) gene was most predominant and was found among Salmonella enterica serovars Blockley, Thomson, London, Enteritidis phage type 14b, Paratyphi B, Virchow and Typhimurium phage types 11 and 507. We also found the bla(TEM-20) gene in S. Paratyphi B var. Java and the bla(TEM-63) gene in S. Isangi. Furthermore, we detected the bla(CTX-M-28) gene in S. Isangi and the bla(CTX-M-3) gene in S. Typhimurium phage type 507. The bla(CTX-M-2) gene was identified in S. Virchow, which also contained a copy of the bla(SHV-2) gene and a copy of the bla(TEM-1) gene. The bla(SHV-12) gene was found alone in S. Concord and together with the bla(TEM-52) gene in S. Typhimurium. Finally, the bla(ACC-1) gene was cloned from a S. Bareilly isolate and was found to be present on indistinguishable plasmids in all S. Bareilly isolates examined as well as in a S. Braenderup isolate and a S. Infantis isolate.

CONCLUSIONS

Our data underscore the diversity of ESBL genes in Salmonella enterica isolated from animals, food products and human patients.

Emergence of extended-spectrum-beta-lactamase (CTX-M-9)-producing multiresistant strains of Salmonella enterica serotype Virchow in poultry and humans in France

During 2002 to 2003, eight Salmonella enterica serotype Virchow poultry and poultry product isolates from various sources (chicken farms, poultry slaughterhouse, or retail store) and one S. enterica rough strain isolated from human feces were found to produce extended-spectrum beta-lactamase CTX-M-9. Poultry and poultry product isolates were recovered from different locations in the southwest of France. The human rough isolate had sequences of flagellin genes (fliC and fljB) typical of serotype Virchow and ribotyping and pulsed-field gel electrophoresis (PFGE) patterns closely similar to those of serotype Virchow strains. PFGE confirmed the clonal relationship between the poultry isolates, while the human isolate displayed a pattern with 94% homology. The bla(CTX-M-9) gene was located on a conjugative plasmid and was shown to be linked to orf513. Plasmid profiling found a very similar EcoRI restriction pattern in six transconjugants studied, including transconjugants obtained from the human isolate. A single hatchery, supplying chicks to the six farms, was identified. Emergence of extended-spectrum beta-lactamase-producing S. enterica strains in food animals is a major concern, as such strains could disseminate on a large scale and lead to antibiotic therapy difficulties.