NDM-1-producing Escherichia coli isolated from pigs induces persistent infection with limited pathogenicity

A Multidrug-Resistant Escherichia coli Caused the Death of the Chinese Soft-Shelled Turtle (Pelodiscus sinensis)

The rapid increase in drug resistance in recent years has become a significant global public health concern. Escherichia coli are ubiquitous bacteria, widely distributed in various environments. This study isolated a bacterial strain (HD-593) from diseased Chinese soft-shelled turtles (Pelodiscus sinensis). The bacterium was identified based on morphology, biochemical tests, and 16S rRNA sequencing, confirming it as E. coli. Drug susceptibility tests revealed that the HD-593 strain was highly resistant to ceftriaxone, enrofloxacin, doxycycline, sulfadiazine, gentamicin, neomycin, florfenicol, carbenicillin, cefradine, erythromycin, penicillin, ampicillin, midecamycin, and streptomycin. Resistance gene analysis confirmed the presence of quinolone resistance genes (oqxA and oqxB), aminoglycoside resistance genes (aac(3)-II and aphA1), a β-lactam resistance gene (blaTEM), and an acylaminol resistance gene (floR) in HD-593. The median lethal dose (LD50) of HD-593 for P. sinensis was 6.53 × 105 CFU/g. Biochemical analysis of serum revealed that HD-593 infection caused a significant reduction in total protein, albumin, and globulin levels, while markedly increasing the levels of aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase. Histopathological analysis revealed severe intestinal damage characterized by villi detachment and muscle cell necrosis. Additionally, extensive splenocyte necrosis with nuclear marginalization, glomerular swelling, and pronounced hepatic steatosis accompanied by distended sinusoids were observed. This study identified a multidrug-resistant E. coli strain from deceased P. sinensis, suggesting that drug resistance genes may circulate in aquaculture ecosystems, posing potential risks to aquaculture.

Ligilactobacillus salivarius regulating translocation of core bacteria to enrich mouse intrinsic microbiota of heart and liver in defense of heat stress

The aim of this study was to elucidate the intrinsic microbiota residing in the heart and liver, which was enriched with Ligilactobacillus salivarius supplementation and its roles in defending anti-oxidation of heat stress. The specific pathogen free (SPF) mice were employed to perform the study. Genomic sequencing showed that the intrinsic microbes in the heart and liver of SPF mice, which were primarily of the genera Burkholderia and Ralstonia, functioned in organic metabolism, environmental information processing, cellular processes, and genetic information processing. Lactobacillus sp. were found in the liver but not in the heart. The heart had a lower bacterial abundance than the liver. A culturomic assay of the heart flushing liquid indicated that the dominant species of bacteria were Ralstonia pickettii, Ralstonia sp._3PA37C10, Ralstonia insidiosa, Burkholderia lata, unclassified _g_ Ralstonia, and unclassified _p_ Pseudomonadota. Intrinsic bacteria exist in the heart due to their inhibitory action against pathogenic Escherichia coli. After, the mice were supplemented with Ligilactobacillus salivarius to optimize the microbiota levels. The dominant bacterial phyla in the liver and heart were Bacillota, Bacteroidota, Pseudomonadota, Thermodesulfobacteriota, andActinomycetota, which comprised 98.2% of total bacteria. The genus Lactobacillus was also abundant. Core bacteria such as Lactobacillus reuteri are translocated from the intestine to the heart and liver. The enriched bacterial composition up-regulated anti-oxidation capacities in the heart and liver. The levels of reactive oxygen species and superoxide dismutase (SOD) were significantly improved compared to those in control (P < 0.01). In conclusion, intrinsic bacteria present in the heart and liver alleviate infection by pathogens, environmental and genetic information processing, and cellular processes during heat stress exposure. Diet with Ligilactobacillus salivarius supplementation regulated the translocation of core bacteria to the heart and liver, improved bacterial composition, and induced a higher anti-oxidative capacity under heat stress.

Characterization of antibiotic determinants and heavy metal resistance genes in Escherichia coli from pigs in Catalonia

More antibiotics are administered to livestock animals than to treat human infections. Industrialization, large animal densities and early weaning mean pigs are exposed to more antibiotics than any other livestock animal. Consequently, antimicrobial resistance (AMR) is common among commensal and pathogenic bacteria. Heavy metals (HMs) are also often used as feed additives for growth promotion and infection prevention alongside antimicrobials, and increased exposure to copper, zinc and cadmium can further encourage AMR through co-selection. In this study, we sequenced an archived collection of 112 Escherichia coli isolates from pigs in Catalonia using short- and long-read sequencing methods to detect AMR and HM tolerance genes. The most common AMR genes were mdfA (84.8%), aph(3″)-Ib (52.7%), bla TEM-1B (45.6%) and aph(6)-Id (45.6%). Genes relevant to public health, such as the extended-spectrum β-lactamases (15.4%), bla CTX-M type or bla SHV, or mobile colistin resistance (mcr) genes (13.4%), such as mcr-1, were also found. HM tolerance genes were present in almost every genome but were rarely located in plasmids, and, in most cases, AMR and HM tolerance genes were not located on the same plasmids. Of the genes predicted to increase tolerance to HMs, only those with activity to mercury were co-located on plasmids alongside other AMR determinants. However, mercury is rarely used in pig farming and does not support a scenario where AMR and HM genes are co-selected. Finally, we identified the exclusive association between mcr-4 and ColE10 plasmid, which may help target interventions to curtail its spread among pig Escherichia coli.

The impact of microplastic-microbe interactions on animal health and biogeochemical cycles: A mini-review

Microplastic (MP) pollution has attracted global attention due to the extensive use of plastic products. The hydrophobic MP surface provides a habitat for multiple microorganisms. Although there have been several studies on the impact of plastic particles on microbial communities, there are few reviews that have systematically summarized the interaction between MPs and microbes and their effects on human health and biochemical circulation. The discussions in this review will take place under the following topics: (1) MPs prompt colonization, biofilm generation, and transfer of environmental microbes; (2) the microbial communities can cause the morphological alterations and biodegradation of MPs; (3) MP-microbe combinations can induce the alteration of intestinal flora and hazard animal health; (4) the biogeochemical cycles affected by MP-microbe interactions. This review will highlight the close interactions between MPs and microorganisms, and provide suggestions for future studies.

Prevalence of Virulence Genes and Antimicrobial Resistances in E. coli Associated with Neonatal Diarrhea, Postweaning Diarrhea, and Edema Disease in Pigs from Austria

Increasing numbers of multi-resistant Escherichia (E.) coli from clinical specimens emphasize the importance of monitoring of their resistance profiles for proper treatment. Furthermore, knowledge on the presence of virulence associated genes in E. coli isolates from European swine stocks is scarce. Consequently, a total of 694 E. coli isolated between 2016 and 2018 from diarrheic piglets of Austrian swine herds were investigated. The isolates were tested for their susceptibility to twelve antibiotics using agar disk diffusion test and for the presence of 22 virulence associated genes via PCR. Overall, 71.9, 67.7, and 49.5% of all isolates were resistant to ampicillin, tetracycline, and trimethoprim-sulfamethoxazole, while resistance levels to gentamicin and fosfomycin were 7.7 and 2.0%, respectively. Resistance frequency to ciprofloxacin was higher than in previous studies. Isolates were more likely to be resistant to ampicillin if they were also resistant to ciprofloxacin. No isolate was resistant to meropenem or amikacin. Virulence genes were detected more frequently in isolates expressing hemolytic activity on blood agar plates. The detection rate of faeG was increased in fimH negative isolates. We assume, that hemolytic activity and absence of fimH could be considered as potential indicators for the virulence of E. coli in piglets.