Antimicrobial resistance and prevalence of diarrheagenic Escherichia coli (DEC), in diarrheic yaks of Tibetan Plateau, China

Landscape of antibiotic resistance genes and bacterial communities in groundwater on the Tibetan Plateau, and distinguishing their difference with low-altitude counterparts

Groundwater is a vital source of drinking water for Tibetans. Antibiotic resistance genes (ARGs) and bacterial communities in groundwater on the Tibetan Plateau remain unclear. Furthermore, the characterization of their differences between high-altitude and low-altitude groundwater is still unrevealed. Herein, 32 groundwater samples were collected on the plateau, and intra- and extracellular ARGs (iARGs and eARGs), and bacterial communities were characterised through qPCR assays to 19 ARGs and 16S rRNA sequencing. It showed top four abundant intra- and extracellular last-resort ARGs (LARGs) were blaOXA-48, mcr-1, vanA, and vanB, whereas dominant common ARGs (CARGs) were tetA and ermB, respectively. CARGs had higher abundances than LARGs, and iARGs were more frequently detected than eARGs. Proteobacteria, an invasive resident phylum, and Firmicutes dominated eDNA release. Network analysis revealed all observed LARGs co-occurred with pathogenic and non-pathogenic bacteria. Community diversity was significantly associated with longitude and elevation, while nitrate correlated with ARGs. Comparative analysis demonstrated eARG frequencies and abundances were higher at high altitudes than at low altitudes. Additionally, Acinetobacter and Pseudomonas specifically dominated at high altitudes. This study reveals the widespread prevalence of ARGs, particularly LARGs, in groundwater on the less-disturbed Tibetan Plateau and underlines the potential risks associated with the LARG-carrying bacteria. ENVIRONMENTAL IMPLICATION: Antibiotic resistance genes (ARGs), which are defined as emerging environmental contaminants, are becoming a global concern due to their ability to confer antibiotic resistance to pathogens. Our findings highlight the prevalence of ARGs, particularly LARGs, in groundwater on the Tibetan Plateau, and the possibility that naturally-occurring pathogenic and non-pathogenic bacteria carry multiple LARGs. In addition, we further reveal differences in the distribution of ARGs and bacterial community between high-altitude and low-altitude groundwater. Collectively, our findings offer an important insight into the potential public risks related to groundwater on the Tibetan Plateau.

Characterization, estimation of virulence and drug resistance of diarrheagenic escherichia coli (DEC) isolated from Tibetan pigs

In this study, we collected feces of Tibetan piglets from Nyingchi area for isolation, culture, identification, virulence gene analysis and drug resistance analysis of Escherichia Coli. The results demonstrated a 41.3% isolation rate of Diarrheagenic Escherichia Coli from Tibetan pigs with the main phylogenetic groups: group A (68.6%) and group B2 (15.7%). Typical E.coli accounted for 76.5%. The highest detection rates of porcine virulence genes were E.coli heat-resistant enterotoxin STb (58.82%) and F107 fimbrial subunit (23.53%). The highest detection rates of virulence genes from Tibetan pigs were fimC (80.39%) and ompA (76.47%). A drug sensitivity test showed that Diarrheagenic Escherichia Coli from Tibetan pigs had high drug resistance rates to mezlocillin, doxycycline and gentamicin. This study comprehensively analyzed the species composition, virulence and drug resistance of Diarrheagenic Escherichia Coli from Tibetan pigs, which provided a clearer and more targeted idea for the prevention and treatment of yellow and white dysentery in Tibetan pigs in the future.

Genome Assessment of Carbapenem- and Colistin-Resistant Escherichia coli from Patients in a Sentinel Hospital in China

Antimicrobial-resistant (AMR) pathogens are a significant threat to public health worldwide. However, the primary carrier of AMR genes, particularly against last-resort antibiotics, is still only partially studied in Chinese hospitals. In a sentinel hospital in China, we collected 157 E. coli strains from patients between January and July 2021. One bla_NDM-1-, nine bla_NDM-5-, and one mcr-1-positive E. coli recovered from inpatients were identified as resistant to meropenem and colistin. There are 37 virulence genes discovered in the 11 strains, including astA in strain EC21Z-147 (O128: H4), which belongs to the enteroaggregative E. coli (EAEC). The bla_NDM gene is distributed into distinct ST types, including ST48, ST616, ST410, ST711, and ST2003, while the mcr-1 gene was identified in ST117. The conjugative plasmids IncX3, IncI1-I, and IncI2 mediated the bla_NDM-5 and mcr-1 genes detected among inpatients. Notably, the youngest age at which mcr-1-positive E. coli has been reported was at one day old, in a child in which the strain is closely related to strains with animal origins. Hospitals are major environments for the spread and dissemination of critical virulence and AMR genes, which requires active monitoring systems at the genome level to surveil the spread of virulence and AMR.

Facile synthesis and biological evaluation of chrysin derivatives

In this paper, novel synthetic methods, including microwave O-alkylation, were used to produce several chrysin derivatives. These compounds were purified, characterised and tested on different cell lines and bacterial strains. From this family, 7-(2,4-dinitrophenoxy)-5-hydroxy-3-phenyl-4H-chromen-4-one (C3) was shown to be extremely active on bacterial strains methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa and Klebsiella pneumoniae as well as having anticancer activity on a range of cancer cell lines with IC50 values less than 30 µM. Chrysin has been known for their anticancer and antimicrobial properties, and this study not only corroborates this but also shows that it is possible to synthesise new improved derivatives with therapeutic possibilities.

Multidrug-Resistant Extended-Spectrum β-Lactamase-Producing Escherichia coli Pathotypes in North Eastern Region of India: Backyard Small Ruminants-Human-Water Interface

A total of 648 diarrheagenic Escherichia coli (DEC) were isolated from calves (n = 219), lambs (n = 87), kids (n = 103), human (n = 193), and water (n = 46) samples. The presence of enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC), and shigatoxigenic E. coli (STEC) was confirmed by PCR-based detection of the Shiga toxin, intimin, hemolysin, and enterotoxin genes. All the isolates were tested for antimicrobial resistance (AMR) by disc diffusion assay. Extended-spectrum β-lactamase (ESBL), carbapenemase, and metallo-beta-lactamase production were determined by double-disk synergy test, modified Hodge test, and combined disk test assays. AMR genes (bla_TEM, bla_SHV, bla_CTX-M, bla_CMY-2, bla_NDM, bla_KPC, bla_VIM, and bla_IMP) were detected by PCR using specific primers. Majority of the isolates from human and water exhibited resistance (>80%) against amoxicillin, ampicillin, aztreonam, cefotaxime, cefixime, gentamicin, ceftazidime, and cefalexin, and against imipenem (70.98%), doripenem (70.47%), and ertapenem (60.62%). Bovine isolates were sensitive to carbapenems. Many isolates (5.75-24.35%) from human, water, calves, kids, and lambs were multidrug resistant (MDR), with resistance against three or more classes of antimicrobials. A total of 170/648 (26.23%) isolates were classified as STEC (9.88%), EPEC (4.32%), and ETEC (12.04%). The AMR genes, including bla_TEM, bla_CMY2, bla_CTX-M, and bla_SHV were detected in the E. coli from all sources. but bla_NDM and bla_KPC were detected only in the isolates from human and water. Three STEC isolates from human origin possessed multiple ESBLs, carbapenemase and metallo-beta-lactamase genes reported for the first time. ESBLs producing EPEC and ETEC in lambs and kids are also reported under this study. Presence of MDR-DEC in domestic animals and common potable water poses public health concern in this region.

Genetic diversity, antimicrobial resistance and extended-spectrum β-lactamase type of Escherichia coli isolates from chicken, dog, pig and yak in Gansu and Qinghai Provinces, China

OBJECTIVES

In this study, the genetic diversity, phylogenetic grouping, antimicrobial resistance and extended-spectrum β-lactamase (ESBL) types of Escherichia coli isolates from chickens, dogs, pigs and yaks in six prefectures of Gansu and Qinghai Provinces, China, were investigated.

METHODS

E. coli was isolated from diarrhoeic and healthy faecal samples. Multilocus sequence typing (MLST), phylogenetic grouping, antimicrobial resistance and ESBL profiles were investigated.

RESULTS

A total of 142 MLST sequence types (STs) were identified from 400 E. coli isolates. eBURST clustering analysis resolved the 142 STs into 19 clonal complexes (CCs) and 67 singletons. PCR phylogenetic typing determined the isolation rate of potentially pathogenic B2/D group isolates among all E. coli to be 12.5% from healthy animal samples and 17.5% from diarrhoeic samples. Antimicrobial susceptibility testing revealed 78 antimicrobial resistance patterns. E. coli resistance rates were highest to doxycycline, ampicillin and tetracycline, whereas polymyxin B and meropenem had the lowest resistance rates. All polymyxin B-resistant E. coli isolates were positive for the mcr-1 gene. A total of 62 ESBL-producing isolates were identified. The ESBL prevalence was 55.0% in diarrhoeic samplings and 5.6% in healthy animals. TEM (82.3%) was the predominant ESBL type, followed by CTM (43.5%) and SHV (19.4%).

CONCLUSION

E. coli isolates in the study area have a high diversity of genetic and antimicrobial resistance patterns but a relatively low isolation rate of potentially pathogenic phylogroups. However, the somewhat high isolation rate of multidrug-resistant E. coli, particularly ESBL-producing isolates, requires continual surveillance of E. coli from animals in these areas.

Class 1 integrons as predominant carriers in Escherichia coli isolates from waterfowls in Hainan, China

This study was conducted to determine the prevalence of integrons and associated gene cassettes in Escherichia coli (E. coli) isolates from waterfowls in Hainan, China. The antimicrobial resistance profile of the isolates was examined by using disc diffusion test. In addition, PCR, RFLP, plasmid replicon typing and DNA sequencing analyses were used for the characterization of integrase genes (class 1, 2 and 3) and associated gene cassettes. Approximatively, 90% of the isolates were positive for the integrase genes by PCR. Specifically, class 1 and class 2 integrons were found in 252 (81%) and 7 (2.3%) strains, respectively. While 21 (6.7%) isolates were positive for both class 1 and class 2 integrons. However, none of the isolate was positive for the class 3 integrons. In addition, 5 various cassette arrays, dfrA1-orfC, aadA2, aadA1, dfrA1-aadA1, and dfrA1-orfC- aadA1, were found within the variable regions (VRs) of class 1 integron isolates. While only single cassette array, dfrA1-sat2- aadA1, was identified within VRs of class 2 integron isolates. We identified incF plasmid as the most common plasmid type, which was detected in 81 of 243 VRs containing isolates. This study is the first report showing the baseline characteristics of integrons in E. coli isolates from waterfowls in Hainan, China. Our results provide evidence of the waterfowl birds as a reservoir of class 1 and class 2 integrons carrying antibiotic resistance gene cassettes. Therefore, strict preventive measures should be taken to avoid the spread of mobile genetic resistance elements in waterfowls in China.

High prevalence of CTX-M belonging to ST410 and ST889 among ESBL producing E. coli isolates from waterfowl birds in China's tropical island, Hainan

The epidemiology and genetic characteristics of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (E. coli) have been widely studied in human and veterinary settings. ESBL-producing E. coli are generally reported in pigs, poultry, and dairy farm animals. Here, we report on the prevalence and genetic characteristics of beta-lactamase producing E. coli isolated from waterfowl birds in Hainan, China. After phenotypic confirmation, genes encoding bla_CTX-M, bla_SHV and bla_TEM were detected by polymerase chain reaction (PCR). The isolates were assigned to different phylogenetic groups, and multi-locus sequence typing (MLST). Taken as a whole, 289 (92.9%) out of 311 E. coli isolates from waterfowl birds were confirmed as ESBL phenotypes by double-disk synergy testing. Subsequent PCR analysis revealed that bla_CTX-M was the predominant ESBL gene identified in 146 (46.9%) isolates, followed by the combination of bla_CTX-M and bla_TEM in 70 (22.5%) isolates. The majority of these positive isolates were assigned to phylogroup B2 (46.2%) followed by phylogroup A (43.6%). In addition, MLST assigned representative ESBL positive isolates (n = 40) to 18 STs, and ST410 (ST23cplx) was the most prevalent population (22.5%). The high prevalence of CTX-M and STs frequently associating with E. coli infections should be of concern as it poses threats to animal and public health. To the best of our knowledge, this is the first comprehensive study to report on the occurrence of ESBL producing E. coli from waterfowl birds in China.