The Siamese crocodile (Crocodylus siamensis) farming industry in China, particularly in Hainan Province, has grown substantially, yet it faces increasing threats from infectious diseases. Providencia spp., especially P. rettgeri, are increasingly reported in reptilian disease outbreaks, but their epidemiological and pathogenic profiles in farmed C. siamensis remain poorly understood. In this study, necropsy and histopathological examination of 18 deceased juvenile Siamese crocodiles from three farms in Hainan Province, China, revealed severe multiorgan lesions indicative of septicemia. Sixty-five Providencia isolates were recovered and assigned to four species-level clusters (P. rettgeri, P. stuartii, P. hangzhouensis, and P. alcalifaciens) via 16S rDNA and fusA phylogenetic analyses. Most isolates exhibited strong motility but weak biofilm-forming ability. Crucially, all 65 isolates were multidrug-resistant and carried diverse antimicrobial resistance genes (ARGs), with 74% harboring class 1 integrons. Virulence-associated genes (VGs) were widespread. Zebrafish challenge assays confirmed that all five representative isolates were pathogenic, with P. rettgeri strains PL-425 and PL-688 exhibiting the highest virulence (100% mortality within 24-30 h). Whole-genome sequencing of PL-425 identified multiple virulence loci related to motility, capsule, adhesion, and toxins. These findings identify multidrug-resistant P. rettgeri as a dominant and highly virulent pathogen in farmed Siamese crocodiles, highlighting its emergence as a significant threat to the industry and underscoring the urgent need for integrated surveillance and antimicrobial stewardship.

The global aquaculture industry is facing increasing threats from multidrug-resistant pathogens, particularly Aeromonas dhakensis, which causes septicemia in crocodiles, causes severe infections in aquatic species, and poses zoonotic risks to humans. To address this challenge, we isolated Bacillus velezensis L09, a novel probiotic, from the gut of Crocodylus siamensis in Hainan Province, China, and evaluated its antimicrobial efficacy. Whole-genome sequencing identified seven antimicrobial biosynthesis gene clusters and diverse carbohydrate-active enzymes, highlighting its metabolic versatility and environmental adaptability. In vitro co-culture experiments revealed a clear time-dependent reduction of A. dhakensis burden—approximately 65 ​% at 24 ​h and 95.7 ​% at 48 h—quantified by Colony-forming unit (CFU) counts and supported by scanning electron microscopy, which showed progressive envelope wrinkling, surface pitting, and overt lysis in treated bacteria. In zebrafish infection models, L09 exhibited dual protective effects against A. dhakensis: competitive exclusion—blocking 78.58 ​% of pathogen adhesion—and immunomodulation. Specifically, L09 upregulated intestinal barrier genes (tjp1, muc2) and activated tlr1/tlr7/tlr22–nfkb–tnfa/il6 signaling axis, thereby enhancing intestinal barrier integrity and activate the host immune response. Histopathological analysis confirmed the restoration of the villus structure and goblet cell repopulation. Safety assessments showed no hemolytic activity and susceptibility to 27 clinically relevant antibiotics. These findings demonstrate that B. velezensis L09 effectively suppresses pathogens, repairs intestinal barriers, and mitigates inflammation, establishing it as an functional adapted probiotic for sustainable aquaculture and a promising alternative for A. dhakensis-associated disease management.

Aeromonas dhakensis, an increasingly prevalent pathogen in tropical areas, presents significant risks to public health and the aquaculture industry. This research evaluates the virulence effects of ugd and phoB gene deletions. The double gene deletion mutant strain ΔugdΔphoB was obtained by further knocking out the ugd gene in the previously constructed single mutant strain ΔphoB. Phenotypic analyses under phosphate-deficient conditions showed marked decreases in both growth and motility for the Δugd and ΔugdΔphoB mutants compared to the wild type. Conversely, under phosphate-rich conditions, growth remained stable, although motility variations were noted. The mutants ΔugdΔphoB and Δugd exhibited diminished resistance to H2O2, ECPase activity, and antimicrobial peptide resistance, alongside reduced adherence to EPC cells. However, the Δugd mutant displayed enhanced biofilm formation. The immunoprotection experiment showed that the protection rate (relative percent survival, RPS) of the Δugd mutant strain was 63.3

Edwardsiella tarda poses a significant challenge to aquaculture industry owing to its pathogenicity and emerging antibiotic resistance. These factors have led to substantial economic losses and growing concerns about food safety. Given the urgent need for sustainable alternatives to antibiotics, bacteriophage therapy has emerged as a promising strategy for targeted pathogen control. This study isolated two bacteriophages exhibiting high lytic activity against E. tarda from wastewater samples collected at a crocodile farm in Hainan, China. These phages, designated as vB_EtaS_2 and vB_EtaS_6, were taxonomically classified within the genus Tlsvirus of the family Drexlerviridae, based on morphological characterization and genomic sequence analysis. In vitro antibacterial assays showed that a multiplicity of infection value of 0.1 exhibited optimal antibacterial efficacy and phage propagation efficiency. Both phages maintained substantial stability under thermal stress (- 20-50 degrees C), across a broad pH range (5-10), and in the presence of low-concentration chloroform. Whole-genome analysis confirmed the absence of antibiotic resistance genes and virulence factors in both phages, ensuring their biosafety profile. Furthermore, in vitro assays demonstrated potent bactericidal activity. In Danio rerio (zebrafish) infection models, a phage cocktail of vB_EtaS_2 and vB_EtaS_6 significantly reduced mortality rates by 40 % (p < 0.05). Collectively, these findings suggest that vB_EtaS_2 and vB_EtaS_6 demonstrate favorable therapeutic potential are promising biocontrol agents against E. tarda. They offer a sustainable, targeted alternative to antibiotics, with translational value in improving pathogen management in crocodile aquaculture.

Serotype Ib and sequence type 261 (Ib/ST261) of Streptococcus agalactiae has emerged as a specific pathogen causing high mortality of bullfrogs (Rana catesbeiana) in Hainan, China, since 2019. However, its virulence gene profile and antimicrobial resistance (AMR) patterns remain poorly characterized. This study is aimed to characterize the virulence gene profile, resistance-associated mutations, and dynamic changes in antimicrobial resistance of S. agalactiae Ib/ST261 collected from diseased bullfrogs in 2019 and 2023 in Hainan, China. By comparing with the isolates in 2019, they shared a stable virulence gene profile (pavA + sip+iagA + cfb+hylB+bibA+cspA+fbsA), and same resistance-associated adaptation mutations of gyrA (S81L), parC (D83Y), pbp1A (Y305F, A604T, N639S), and pbp2B (V79A, S247F, S313P, N412D, T656I), as well as similar weak biofilm formation. Though most of them exhibited similarly high resistance to tetracycline (97

Aeromonas dhakensis, an emerging opportunistic pathogen prevalent in tropical regions, poses significant threats to both public health and aquaculture industries. This study elucidates the synergistic effects of dual deletion of the two-component systems PhoBR and KdpDE on virulence attenuation. Using homologous recombination and seamless cloning techniques, we constructed a ΔphoBRΔkdpE double mutant based on our laboratory's existing ΔphoBR mutant. Notably, phenotypic characterization revealed that the double mutant maintained comparable growth kinetics to wild-type, ΔphoBR mutant, and complemented strains under high-potassium conditions. However, under potassium-limiting conditions, ΔphoBRΔkdpE exhibited significantly impaired growth, compromised antioxidant capacity, diminished biofilm formation, reduced extracellular protease activity, and attenuated cell adhesion compared to controls. Furthermore, the mutant demonstrated enhanced susceptibility to antimicrobial peptides and marked virulence attenuation in zebrafish models, as evidenced by a substantially higher LD50 (6.53 × 108 CFU/mL) compared to ΔphoBR (1.15 × 108 CFU/mL) and wild-type strains (2.91 × 107 CFU/mL). Intriguingly, immunization trials showed moderate protective efficacy (43.3

The PhoPQ and QseBC two-component systems (TCSs) regulate virulence and promote bacterial survival in vitro and in vivo, enabling competition in microenvironments or interactions with the host. However, their potential contributions to vaccine development remain uncharacterized in Edwardsiella tarda, a notorious pathogen that poses a substantial economic threat to the food and aquaculture industries. In this study, our data revealed that the deletion of either phoPQ or qseBC did not impair the growth and motility of E. tarda, except that PhoPQ inactivation led to growth retardation under magnesium (Mg2+)-limiting conditions (50 μM). Besides, the mutants of PhoPQ TCS enhanced sensitivities to polymyxin B, clindamycin, chloramphenicol, minocycline, oxytetracycline, and sulfafurazole, but QseBC TCS mutants showed the opposite trend. However, survival under oxidative and osmotic stress and biofilm formation capability were substantially reduced, especially in the double TCS mutant ΔqseBCΔphoP, which was the most severely impaired. Animal model results also demonstrated that the ΔqseBCΔphoP mutant was the most attenuated, with an LD50 of 3.77 × 106, followed by ΔphoP (6.7 × 105), ΔqseB (7.9 × 104), by comparing with the wild-type (WT) strain (7.55 × 104). Differential gene expression analysis revealed significant downregulation of most tested virulence genes (including citC, flhC, flhD, fliP, luxS and mukF) in the ΔqseBCΔphoP strain. However, immune protection assay revealed a trade-off: ΔqseBCΔphoP exhibited lower relative percent survival (RPS: 29%) than ΔphoP (RPS: 53%), this was supported by elevated levels of specific antibodies in serum from fish vaccinated with ΔphoP, compared to those vaccinated with the strain ΔqseBCΔphoP. Furthermore, transcriptional profiling suggested that the enhanced protection conferred by the strain ΔphoP may stem from PhoPQ's global regulatory role in controlling LPS biosynthesis, metabolism, transport systems, transferase activity, and stress resistance mechanisms. Together, these findings demonstrate that dual TCS disruption synergistically reduces virulence factors (e.g., biofilm formation, stress tolerance) and pathogenicity but compromises immunogenicity. Importantly, PhoPQ shows greater potential as a vaccine target compared to QseBC for live attenuated vaccine (LAV) development against E. tarda.

Aeromonas dhakensis is an emerging pathogen responsible for infections in humans, livestock, and aquatic species, posing a threat to public health and aquaculture. This study investigates the roles of two critical genes, arnA and ugd, which are involved in polymyxin resistance, by creating single (ΔarnA) and double (ΔugdΔarnA) deletion mutants in A. dhakensis. The mutants showed impaired motility, increased sensitivity to polymyxin, and altered biofilm formation. Virulence was reduced in zebrafish models, with ΔarnA exhibiting a 2.03-fold increase in median lethal dose (LD50), and ΔugdΔarnA showing a 7.13-fold increase. Immunization with these mutants provided significant protection, with survival rates of 65 % and 40 %, respectively, after challenge with the wild-type isolate, compared to the control group. These results underscore the critical roles of arnA and ugd in polymyxin resistance and virulence, highlighting their potential as targets for vaccine development in aquaculture disease control.

Aeromonas dhakensis (A. dhakensis), a highly virulent and multidrug-resistant zoonotic pathogen, poses a severe threat to the sustainable development of aquaculture (e.g., crocodile farming) and food safety. In this study, we aimed to develop an antibiotic-alternative prevention and control strategy. To this end, we isolated a phage vB_AdhP_L12 with strong lytic activity against A. dhakensis from general hospital domestic sewage. Morphological observation and phylogenetic analysis identified vB_AdhP_L12 as a novel phage belonging to the genus Teseptimavirus in the family Autographiviridae, which is characterized by an icosahedral head and a short, non-contractile tail. Environmental stability assays demonstrated that vB_AdhP_L12 maintained stable activity at temperatures ranging from −20 °C to 37 °C and pH values ranging from 4 to 11 and exhibited tolerance to low concentrations of chloroform, indicating its suitability for aquaculture environments. Host range determination revealed that it specifically lysed eight strains of A. dhakensis isolated from crocodiles, with no activity against other common aquatic bacterial strains. Whole-genome sequencing revealed that the phage has a linear double-stranded DNA genome of 38,749 bp, containing 42 open reading frames and lacks antibiotic resistance genes, virulence factors, and lysogeny-related genes, confirming its high level of biosafety. In vitro experiments confirmed that vB_AdhP_L12 exhibited optimal bacteriostatic effects at a multiplicity of infection of 0.01, efficiently lysing A. dhakensis and protecting Caco-2 and EPC cells from damage. In the zebrafish infection model, immersion treatment with vB_AdhP_L12 resulted in a survival rate of 63.33% in the experimental group, with a significant reduction in mortality. Moreover, pathological damage to intestinal tissues was effectively repaired. Quantitative PCR results revealed that the overexpression of pro-inflammatory cytokines was markedly suppressed, while the levels of anti-inflammatory cytokines and specific antibodies were significantly upregulated. These findings indicate that phage immersion treatment can modulate the host immune response to a certain extent. Nevertheless, whether such immunomodulatory effects arise directly from phage–host interactions or represent a secondary consequence of bacterial clearance remains to be further explored. In conclusion, phage vB_AdhP_L12 has several advantages, including strong host specificity, excellent environmental adaptability, high biosafety, and significant in vitro and in vivo therapeutic efficacies. This study provides a novel technical prototype for the sustainable prevention and control of A. dhakensis infections in crocodile farming, serving as a promising antibiotic alternative with strong potential for translation to aquaculture practice. This study is of critical significance for alleviating the antibiotic resistance crisis and ensuring the safety of aquaculture.

The PhoBR two-component system is a critical regulator of virulence in many bacterial pathogens, but its role in Aeromonas dhakensis remains poorly characterized. In this study, three markerless knockout mutants (zphoB, zphoR and zphoBR) were constructed to explore the function of PhoBR. Under low phosphate conditions (0.2 mM Pi), physiological analyses showed that all mutants exhibited defects in growth, motility, biofilm formation and resistance to acid, with zphoBR also showing resistance to H2O2, while no significant changes were observed in extracellular protease secretion. Cell adhesion and zebrafish infection assays indicated that PhoBR is crucial for A. dhakensis adhesion to EPC cells. The zphoBR mutant had the highest LD50 value (1.77 x 10(7) CFU per fish), which was 38.15 times higher than that of the wild type strain. Additionally, zphoBR conferred the highest relative percent survival (RPS) of 61.5 % in zebrafish following two immunizations. These findings suggest that PhoBR positively regulates virulence in A. dhakensis and that the zphoBR mutant could serve as a potential vaccine candidate for the prevention of aeromoniasis in aquaculture.

Aeromonas dhakensis is an emerging zoonotic pathogen in aquaculture, yet the genetic determinants underlying its virulence and immunogenicity remain incompletely understood. Among its potential virulence-associated factors, the wecA gene encodes UDP-N-acetylglucosamine-1-phosphate transferase, a key enzyme in lipopolysaccharide (LPS) core oligosaccharide biosynthesis. In this study, an unmarked wecA deletion mutant (ΔwecA) and complemented strain (CΔwecA) were constructed to investigate the role of wecA in physiology, pathogenicity, and vaccine potential through in vitro assays, cell culture infection, and animal models including Caenorhabditis elegans and zebrafish. Deletion of wecA did not affect growth, swimming motility, or biofilm formation, but significantly increased sensitivity to polymyxin B, compromised membrane integrity, and enhanced swarming motility and hemolytic activity. The ΔwecA mutant exhibited markedly reduced adhesion and early cytotoxicity toward EPC cells and showed substantial attenuation in C. elegans and zebrafish, with higher LD50 values and prolonged survival. Zebrafish immunized with ΔwecA achieved considerable protection against lethal challenge (relative percent survival of 46.7 % after primary and 55.6 % after booster immunization), accompanied by robust activation of both transcriptional (qRT-PCR) and protein-level (ELISA) immune responses, including upregulation of mucosal barrier (mucin-2), adaptive humoral (IgM), innate immune effectors (MHC-I, TLR2, lysozyme), and various pro-inflammatory cytokines. These results indicate that wecA is crucial for envelope homeostasis and virulence in A. dhakensis. Its deletion results in a stable attenuated phenotype capable of inducing protective immunity, demonstrating the potential of a live-attenuated vaccine strategy to reduce disease burden and biosecurity risks in international aquaculture systems.

Aeromonas dhakensis is an emerging pathogen linked to systemic infections in diverse animal hosts, with rising prevalence posing a growing threat to animal health. Although the argH gene is traditionally associated with arginine biosynthesis, its role in virulence remains unclear. In this study, a ΔargH mutant of A. dhakensis wild-type C4-1 was constructed to investigate its contribution to pathogenicity. The ΔargH mutant exhibited significantly reduced virulence, as evidenced by reduced biofilm formation, motility, extracellular protease activity, adhesion, and resistance to oxidative stress. Furthermore, the ΔargH mutant exhibited heightened susceptibility to antimicrobial peptides, suggesting a role for argH in stress adaptation. Transcriptomic analysis revealed 518 differentially expressed genes (DEGs), with significant enrichment in pathways associated with membrane structure, flagellar assembly, secretion systems, and biofilm development. These findings indicate that argH acts as a pleiotropic regulator influencing multiple aspects of A. dhakensis virulence.

Aeromonas dhakensis is a zoonotic pathogen responsible for severe infections in both humans and aquatic organisms. The increasing incidence of antibiotic resistance in A. dhakensis strains underscores the urgent need for alternative control strategies, such as vaccines. In this study, a quadruple gene deletion mutant of A. dhakensis Δaart was generated by targeting the virulence genes: aerA, ahh1, rtxA, and th. The Δaart exhibited significantly reduced virulence in hemolytic activity and cytotoxicity, whereas no impairment in bacterial growth. Using zebrafish model, the LD50 of Δaart was 136-fold higher than that of the wild-type strain. Following immunization, the peak expression of innate immune-related genes (SOD, CAT, LZM, TNF-α, IL-6, IL-1β) in the kidney was observed on day 3, followed by a decline; MHC-I peaked on day 7, and IL-10 on day 14. Similar trends were noted in the intestine, while MHC-I did not show significant changes. Notably, IgM levels in the immunized zebrafish increased significantly at day 7 post-immunization, peaked at day 14, and remained at a high level at day 28. Furthermore, the Δaart provided substantial protection against wild-type A. dhakensis infection, with a relative percent survival (RPS) of 56.67%, and less lesion was observed in intestines and kidney histopathology. These findings suggest that the Δaart mutant holds promise as a safe and effective live-attenuated vaccine candidate for controlling A. dhakensis infections.

Antimicrobial resistance profiles of Aeromonas have been used as an effective indicator for monitoring resistances in aquatic environments. Integron gene cassettes are a major reservoir of antibiotic resistance genes in bacteria. To date, little has been reported on the antimicrobial resistance or integrons of Aeromonas in bullfrog aquaculture. In this study, 27 isolates belonging to four Aeromonas species (A. hydrophila, A. veronii, A. caviae, and A. jandaei) were isolated from farmed diseased American bullfrogs (Rana catesbeiana). all of them were multidrug-resistant, exhibiting resistance to at least seven drugs from five antibiotic classes. Class 1 integrons (intI1s), containing nine types of gene cassette arrays encoding resistance to trimethoprim (dfrA1, dfrA12, dfrA15, dfrA17), streptomycin/spectinomycin (aadA2), fluoroquinolones/aminoglycosides (aac(6′)-Ib-cr), rifampin (arr3), proline-rich antimicrobial peptides (ptrB), and multiple antimicrobial agents involved in biofilm development (dgs), were detected in 26 (26/27, 96.3%) of the isolates. Seven patterns were identified, and six of them contained two or three gene cassettes, in 27 isolates. This work highlights unusually high frequency (21/27, 77.8%) of multiple intI1 gene cassette arrays and three novel intI1 gene cassettes or arrays (dgc, ptrB, and aac(6′)-Ib-cr-arr3) in the isolates of Aeromonas spp. from American bullfrogs.

AimTo describe the histopathology and etiology of an outbreak of respiratory disease at a Ptyas mucosus farm in Hainan, China.Methods and resultsThe etiology was confirmed by gross examination and microscopic analysis. The bacterial isolates from blood and internal organs were identified by biochemical analysis and 16S rRNA gene sequencing. The virulence and antibiotic resistance characteristics of the isolates were further demonstrated by polymerase chain reaction (PCR), disk diffusion testing, and LD50 analysis in Kunming mice. Histopathological analysis of the diseased P. mucosus revealed systemic lesions, including severe airway obstruction with large numbers of inflammatory cells and cellulose exudates in the lungs; severe multifocal hepatocyte vacuolar degeneration and necrosis in the liver with excessive inflammatory exudates and chronic granuloma; splenic hemorrhage and partial loss of splenic structure; and renal vascular and interstitial congestion. Providencia rettgeri was isolated from the blood and multiple internal organs (liver, spleen, kidneys, and lungs). All examined isolates (H1, H4, and H13) were multidrug-resistant but sensitive to four antibiotics—cefepime, imipenem, chloramphenicol, and ciprofloxacin. Both H1 and H4 carried five resistance genes [blaOXA, tet(A), tet(B), tet(E), and aac (3)-IIa], whereas H13 only carried the tet(A) gene. The dominant virulence pattern of the three isolates was hlyA + ZapA + luxS + rsbA. The virulence of H1 strain was tested, and its 50% lethal dose (LD50) in mice was 2.29 × 108 CFU ml−1.ConclusionTo our knowledge, this is the first study to describe an outbreak of bacteremia caused by P. rettgeri in farmed rat snakes.Significance and impact of the studyThe results highlight that P. rettgeri is an emerging bacterial pathogen in farmed reptiles.

Background:Sheep are a rarely raised livestock in Hainan Island, China, because of the unfavorable tropical marine climate. Here, this article reports a severe pneumonia in the sheep breeding and domestication facility caused acute mortality during the winter 2021-2022. Methods:Six sheep were clinically dissected and histopathologically observed. The bacteria were isolated and cultured by traditional methods and identified by 16S rRNA sequencing. The genotypes, serotypes, virulence genes and antimicrobial resistance genes were analyzed by PCR and whole genome sequencing. The pubMLST website was used for phylogenetic analysis of related strains. Kirby-Bauer disk diffusion method was used for antimicrobial susceptibility test. The antimicrobial susceptibility test standard was referred to the Clinical and Laboratory Standards Institute (CLSI). The virulence of bacteria was detected by mouse infection model. Results:Etiology and histopathology examination of the pneumonia reveled pulmonary abscess and alveolar neutrophilia and pulmonary fibrinous exudates. Escherichia coli was the only bacterial species isolated, primarily from the lungs and blood of the six dead or moribund sheep, a total of 29 E. coli strains were isolated. Antimicrobial resistance profiling shows that all the isolates were resistant to six agents (penicillin, ampicillin, cephalothin, neomycin, erythromycin, and vancomycin) belonging to five classes of antibiotics, classifying them as multi drug resistant (MDR). Furthermore, genotyping analysis revealed all strains were common with 11-17 virulence factors indicating high pathogenicity. The lab mice infection model shows that all strains severely affect the health status particularly weight loss, lethargy, pneumonia and shortly lead to death. The molecular epidemiological analysis indicated most strains share the same genotype as previously reported strains in humans and other farmed animals this suggests a high possibility of cross-species transmission (CST) of virulent and MDR isolates. This CST could be from sheep to humans and other farmed animals or from humans and other farmed animals to sheep. Conclusion:Therefore, this study indicates that E. coli is an emerging threat that causes sheep pneumonia in Hainan, and the quarantine of contacts is important to control the spread of virulent E. coli and the transmission of acquired resistance genes between humans and farmed animals such as sheep.

Highlights1. ΔphoBR is defective in growth, motility, biofilm formation, adhesion to EPC cell, resistance to acid and H2O2.2. ΔphoBR is more attenuated to zebrafish than ΔphoB and ΔphoR.3. ΔphoBR confers 61.5% of RPS to zebrafish against the isogenous wild strain by double vaccinations.

Edwardsiella tarda is a Gram-negative, facultative anaerobic rod-shaped bacterium and the causative agent of the systemic disease "Edwardsiellosis". It is commonly prevalent in aquatic organisms with subsequent economic loss and hence has attracted increasing attention from researchers. In this study, we investigated the complete genome sequence of a highly virulent isolate Edwardsiella tarda SC002 isolated from hatchlings of the Siamese crocodile. The genome of SC002 consisted of one circular chromosome of length 3,662,469 bp with a 57.29% G+C content and four novel plasmids. A total of 3,734 protein-coding genes, 12 genomic islands (GIs), 7 prophages, 48 interspersed repeat sequences, 248 tandem repeat sequences, a CRISPR component with a total length of 175 bp, and 171 ncRNAs (tRNA = 106, sRNA = 37, and rRNA = 28) were predicted. In addition, the coding genes of assembled genome were successfully annotated against eight general databases (NR = 3,618/3,734, COG = 2,947/3,734, KEGG = 3,485/3,734, SWISS-PROT = 2,787/3,734, GO = 2,648/3,734, Pfam = 2,648/3,734, CAZy = 130/3,734, and TCDB = 637/3,734) and four pathogenicity-related databases (ARDB = 11/3,734, CARD = 142/3,734, PHI = 538/3,734, and VFDB = 315/3,734). Pan-genome and comparative genome analyses of the complete sequenced genomes confirmed their evolutionary relationships. The present study confirmed that E. tarda SC002 is a potential pathogen bearing a bulk amount of antibiotic resistance, virulence, and pathogenic genes and its open pan-genome may enhance its host range in the future.

分离女性阴道中的粪肠球菌(Enterococcus faecalis),通过PCR和Kirby-Bauer(K-B)纸片扩散法探究其毒力基因、耐药基因及其耐药表型,为揭示粪肠球菌感染机制及其临床治疗提供科学依据.结果表明:从157个样品中共分离出22株粪肠球菌;在这些粪肠球菌中:毒力基因检出率为efaA(100％)、asa1(90.9％)、cylA(90.9％)、fsr(90.9％)、cpd(90.9％)、acm(86.4％)、gelE(81.8％)、esp(68.2％)、ace(54.5％)和 hyl(0);耐药基因的检出率为 vanA(0)、vanB(0)、vanC(18.2％)、aac(40.9％)、ant(6)-1(59.1％)、ermB(68.2％)、mefA(54.5％)、tetM(72.2％)和tem(81.8％);药敏结果显示粪肠球菌对万古霉素、呋喃妥因、利奈唑胺、替考拉宁敏感;对其他抗菌药物具不同程度的耐药.由此得出,阴道易受粪肠球菌感染,体外实验支持糖肽类抗菌药物可用于粪肠球菌感染的临床治疗.

Pseudomonas aeruginosa is a common infectious agent associated with respiratory diseases in boas and pythons, however, the histopathology, resistance and virulence are yet described for this species. In this study, we investigated a dying Burmese python rescued from tropical rainforest in Hainan. Clinical signs were open-mouthed breathing, abnormal shedding and anorexia. Abundant yellow mucopurulent secretions were observed in highly ectatic segmental bronchi by postmortem. Histopathological lesions included systemic pneumonia, enteritis, nephritis and carditis. P. aeruginosa was the only species isolated from heart blood, kidney, trachea and lung. The phenotype analysis demonstrated that the isolates had strong biofilm, and were sensitive to amikacin, spectinomycin, ciprofloxacin, norfloxacin and polymyxin B, moreover, the LD50 of the most virulent isolate was 2.22x10(5) cfu/mL in a zebrafish model. Molecular epidemiological analysis revealed that the isolates belonged to sequence type 3495, the common gene patterns were toxA + exoSYT + phzIM + plcHN in virulence and catB + bla(TEM) + ant (3'')-I+ tetA in resistance. This study highlights that P. aeruginosa should be worth more attention in wildlife conservation and raise the public awareness for the cross infection and cross spread between animals and human.