Search Results (6)

Proteus mirabilis is a significant foodborne opportunistic pathogen associated with various nosocomial infections. Chicken farms may serve as an important reservoir for P. mirabilis. However, research on antibiotic resistance and genomic features of P. mirabilis in China’s poultry industry is limited. This study isolates P. mirabilis from a breeder farm in China and investigates the dissemination of P. mirabilis and clinically significant antibiotic resistance genes (ARGs), including bla_NDM and bla_CTX-M. From 510 samples, 69 isolates were obtained, classified into 11 sequence types (STs), with ST135 and ST175 predominating. A total of 39 ARGs were detected, including fosA3, floR, bla_CTX-M-3, bla_CTX-M-65, and bla_NDM-1. Genetic analysis revealed that bla_NDM-1 was exclusively located on Salmonella genomic island 1 (SGI1), while bla_CTX-M was found in various mobile genetic elements (MGEs), including Tn7, SXT/R391 integrative conjugative elements (ICEs), Proteus mirabilis genomic resistance island 1 (PmGRI1), and SGI1. Notably, many isolates carried multiple MGEs, suggesting frequent horizontal transfer of ARGs in P. mirabilis. These findings underscore the role of P. mirabilis in carrying and spreading antibiotic resistance, posing significant risks to the poultry industry and public health. Full article

In recent years, Salmonella enterica subsp. enterica serovar Mbandaka (S. Mbandaka) has been increasingly isolated from laying hens and shell eggs around the world. Moreover, this serovar has been identified as the causative agent of several salmonellosis outbreaks in humans. Surprisingly, little is known about the characteristics of this emerging serovar, and therefore, we investigated antimicrobial resistance, virulence, and prophage genes of six selected Brazilian strains of Salmonella Mbandaka using Whole Genome Sequencing (WGS). Multi-locus sequence typing revealed that the tested strains belong to Sequence Type 413 (ST413), which has been linked to recent multi-country salmonellosis outbreaks in Europe. A total of nine resistance genes were detected, and the most frequent ones were aac(6′)-Iaa, sul1, qacE, bla_OXA-129, tet(B), and aadA1. A point mutation in ParC at the 57th position (threonine → serine) associated with quinolone resistance was present in all investigated genomes. A 112,960 bp IncHI2A plasmid was mapped in 4/6 strains. This plasmid harboured tetracycline (tetACDR) and mercury (mer) resistance genes, genes contributing to conjugative transfer, and genes involved in plasmid maintenance. Most strains (four/six) carried Salmonella genomic island 1 (SGI1). All S. Mbandaka genomes carried seven pathogenicity islands (SPIs) involved in intracellular survival and virulence: SPIs 1-5, 9, and C63PI. The virulence genes csgC, fimY, tcfA, sscA, (two/six), and ssaS (one/six) were absent in some of the genomes; conversely, fimA, prgH, and mgtC were present in all of them. Five Salmonella bacteriophage sequences (with homology to Escherichia phage phiV10, Enterobacteria phage Fels-2, Enterobacteria phage HK542, Enterobacteria phage ST64T, Salmonella phage SW9) were identified, with protein counts between 31 and 54, genome lengths of 24.7 bp and 47.7 bp, and average GC content of 51.25%. In the phylogenetic analysis, the genomes of strains isolated from poultry in Brazil clustered into well-supported clades with a heterogeneous distribution, primarily associated with strains isolated from humans and food. The phylogenetic relationship of Brazilian S. Mbandaka suggests the presence of strains with high epidemiological significance and the potential to be linked to foodborne outbreaks. Overall, our results show that isolated strains of S. Mbandaka are multidrug-resistant and encode a rather conserved virulence machinery, which is an epidemiological hallmark of Salmonella strains that have successfully disseminated both regionally and globally. Full article

Salmonella enterica serovar Derby (S. Derby) ranks fifth among nontyphoidal Salmonella serovars causing human infections in the European Union. S. Derby isolates (36) collected between 2006 and 2018 in a Spanish region (Asturias) from human clinical samples (20) as well as from pig carcasses, pork- or pork and beef-derived products, or wild boar (16) were phenotypically characterized with regard to resistance, and 22 (12 derived from humans and 10 from food-related samples) were also subjected to whole genome sequence analysis. The sequenced isolates belonged to ST40, a common S. Derby sequence type, and were positive for SPI-23, a Salmonella pathogenicity island involved in adherence and invasion of the porcine jejune enterocytes. Isolates were either susceptible (30.6%), or resistant to one or more of the 19 antibiotics tested for (69.4%). Resistances to tetracycline [tet(A), tet(B) and tet(C)], streptomycin (aadA2), sulfonamides (sul1), nalidixic acid [gyrA (Asp87 to Asn)] and ampicillin (bla_TEM-1-like) were detected, with frequencies ranging from 8.3% to 66.7%, and were higher in clinical than in food-borne isolates. The fosA7.3 gene was present in all sequenced isolates. The most common phenotype was that conferred by the tet(A), aadA2 and sul1 genes, located within identical or closely related variants of Salmonella Genomic Island 1 (SGI1), where mercury resistance genes were also present. Diverse IncI1-I(α) plasmids belonging to distinct STs provided antibiotic [bla_TEM-1, tet(A) and/or tet(B)] and heavy metal resistance genes (copper and silver), while small pSC101-like plasmids carried tet(C). Regardless of their location, most resistance genes were associated with genetic elements involved in DNA mobility, including a class one integron, multiple insertion sequences and several intact or truncated transposons. By phylogenetic analysis, the isolates were distributed into two distinct clades, both including food-borne and clinical isolates. One of these clades included all SGI1-like positive isolates, which were found in both kinds of samples throughout the entire period of study. Although the frequency of S. Derby in Asturias was very low (0.5% and 3.1% of the total clinical and food isolates of S. enterica recovered along the period of study), it still represents a burden to human health linked to transmission across the food chain. The information generated in the present study can support further epidemiological surveillance aimed to control this zoonotic pathogen. Full article

The monophasic 4,[5],12:i:-variant of Salmonella enterica serovar Typhimurium with sequence type ST34 has become one of the most prevalent non-typhoidal salmonellae worldwide. In the present study, we thoroughly characterized seven isolates of this variant detected in a Spanish hospital and selected based on cefotaxime resistance and cefoxitin susceptibility, mediated by bla_CTX-M-9. For this, conventional microbiological techniques, together with whole genome sequencing performed with the Illumina platform, were applied. All selected isolates carried the resistance region RR or variants therein, and most also contained the SGI-4 genomic island. These chromosomal elements, typically associated with monophasic S. Typhimurium ST34, confer resistance to traditional antibiotics (ampicillin, streptomycin, sulfonamides, and tetracycline) and tolerance to heavy metals (mercury, silver, and copper). In addition, each isolate carried a large IncHI2-ST1 conjugative plasmid containing additional or redundant resistance genes. All harbored the bla_CTX-M-9 gene responsible for cefotaxime resistance, whereas the qnrA1 gene mediating fluoroquinolone resistance was detected in two of the plasmids. These genes were embedded in ISCR1-bearing complex class 1 integrons, specifically In60-like and In36-like. The mcr-9 gene was present in all but one of the IncHI2-ST1 plasmids found in the analyzed isolates, which were nevertheless susceptible to colistin. Most of the resistance genes of plasmid origin clustered within a highly complex and variable region. The observed diversity results in a wide range of resistance phenotypes, enabling bacterial adaptation to selective pressure posed by the use of antimicrobials. Full article

Salmonella genomic island 1 (SGI1) is an integrative mobilisable element that plays an important role in the capture and spread of multiple drug resistance. To date, SGI1 has been found in clinical isolates of Salmonella enterica serovars, Proteus mirabilis, Morganella morganii, Acinetobacter baumannii, Providencia stuartii, Enterobacter spp, and recently in Escherichia coli. SGI1 preferentially targets the 3´-end of trmE, a conserved gene found in the Enterobacteriaceae and among members of the Gammaproteobacteria. It is, therefore, hypothesised that SGI1 and SGI1-related elements (SGI1-REs) may have been acquired by diverse bacterial genera. Here, Bitsliced Genomic Signature Indexes (BIGSI) was used to screen the NCBI Sequence Read Archive (SRA) for putative SGI1-REs in Gammaproteobacteria. Novel SGI-REs were identified in diverse genera including Cronobacter spp, Klebsiella spp, and Vibrio spp and in two additional isolates of Escherichia coli. An extensively drug-resistant human clonal lineage of Klebsiella pneumoniae carrying an SGI1-RE in the United Kingdom and an SGI1-RE that lacks a class 1 integron were also identified. These findings provide insight into the origins of this diverse family of clinically important genomic islands and expand the knowledge of the potential host range of SGI1-REs within the Gammaproteobacteria. Full article

Salmonella enterica serovar Kentucky (S. Kentucky) sequence type 198 has emerged as a global zoonotic pathogen. We explored Salmonella enterica serovar Kentucky ST198 samples from the broiler chicken supply chain and patients between 2010 and 2016. Here, we collected 180 S. Kentucky isolates from clinical cases and the poultry supply chain. We performed XbaI pulsed-field gel electrophoresis and multilocus sequence typing. We assessed mutations in the quinolone resistance-determining regions and screened for the presence of the Salmonella genomic island 1 (SGI1). We determined that 63 (35.0%) of the 180 isolates were S. Kentucky ST198. Chinese strains of S. Kentucky ST198 have a high transmission of ciprofloxacin resistance (38/63, 60.3%) and a high risk of multidrug resistance. The quinolone resistance of the S. Kentucky ST198 strain found in China may be due to mutations in its quinolone resistance-determining region. Our study firstly revealed that ciprofloxacin-resistant S. Kentucky ST198 strains can undergo cross-host transmission, thereby causing a serious foodborne public health problem in China. Full article