Current trends of human infections and antibiotic resistance of the genus Shewanella

Antibiotic Resistance of Bacteria Isolated from Clinical Samples and Organs of Rescued Loggerhead Sea Turtles (Caretta caretta) in Southern Italy

Antimicrobial resistance affects all environments, endangering the health of numerous species, including wildlife. Increasing anthropic pressure promotes the acquisition and dissemination of antibiotic resistance by wild animals. Sea turtles, being particularly exposed, are considered sentinels and carriers of potential zoonotic pathogens and resistant strains. Therefore, this study examined the antibiotic resistance profiles of bacteria isolated from loggerhead sea turtles hospitalised in a rescue centre of Southern Italy over a 9-year period. Resistance to ceftazidime, doxycycline, enrofloxacin, flumequine, gentamicin, oxytetracycline and sulfamethoxazole-trimethoprim was evaluated for 138 strains isolated from the clinical samples or organs of 60 animals. Gram-negative families were the most isolated: Vibrionaceae were predominant, followed by Shewanellaceae, Pseudomonadaceae, Enterobacteriaceae and Morganellaceae. These last three families exhibited the highest proportion of resistance and multidrug-resistant strains. Among the three Gram-positive families isolated, Enterococcaceae were the most represented and resistant. The opportunistic behaviour of all the isolated species is particularly concerning for diseased sea turtles, especially considering their resistance to commonly utilised antibiotics. Actually, the multiple antibiotic resistance was higher when the sea turtles were previously treated. Taken together, these findings highlight the need to improve antimicrobial stewardship and monitor antibiotic resistance in wildlife, to preserve the health of endangered species, along with public and environmental health.

Emergence of mcr-4.3 genes in a novel Shewanella specie isolated from the Arctic environment

Mobile colistin resistance (mcr) genes are pivotal contributors to last-line of antimicrobial resistance in human infections. Shewanella, historically recognized as a natural environmental bacterium with metal reduction capabilities, recently has been observed in clinical settings. However, limited knowledge has been explored on genetic differences between strains from non-clinical and clinical strains. In this study, we conducted the whole genome sequencing on six Arctic strains, illustrated the phylogenetic relationships on published 393 Shewanella strains that categorized the genus into four lineages (L1 to L4). Over 86.4% of clinical strain group (CG) strains belonged to L1 and L4, carrying mcr-4 genes and a complete metal-reduction pathways gene cluster. Remarkably, a novel Arctic Shewanella strain in L3, exhibits similar genetic characteristics with CG strains that carried both mcr-4 genes and a complete metal reduction pathway gene cluster. It raised concerns about the transmission ability from environment to clinic setting causing in the potential infections, and emphasized the need for monitoring the emerging strains with human infections.

Left knee septic monoarthritis in a pediatric patient due to shewanella putrefaciens: case report and literature review

BACKGROUND

Shewanella putrefaciens is a gram-negative, nonfermenting, oxidase-positive, hydrogen sulfide-producing bacillus and a halophilic bacterium, known for causing unusual infections in humans and often regarded as an opportunistic pathogen. Its diverse symptoms have a significant impact on human health, with 260 documented disorders reported in the literature over the last 40 years, highlighting its potential danger.

CASE PRESENTATION

We present the case of a previously healthy 15-year-old male patient who sustained a self-inflicted sharp-object injury while working in the field, resulting in secondary septic monoarthritis due to Shewanella putrefaciens.

CONCLUSIONS

This case highlights the bacteriological and clinical characteristics, as well as the antibiogram, of Shewanella spp. Given the recent increase in notifications of Shewanella infections, predominantly by S. algae and S. putrefaciens, it is essential to consider these pathogens in patients with a history of contact with bodies of water. Special attention must be paid to their resistance patterns in patient management to prevent the development of intrinsic antimicrobial resistance.

Damage of polyethylene microplastics on the intestine multilayer barrier, blood cell immune function and the repair effect of Leuconostoc mesenteroides DH in the large-scale loach (Paramisgurnus dabryanus)

Polyethylene microplastics (PE-MPs) has become a global concern due to their widespread distribution and hazardous properties in aquatic habitats. In this study, the accumulation effect of PE-MPs in the intestine of large-scale loach (Paramisgurnus dabryanus) was explored by adding different concentrations of PE-MPs to the water, the destination of PE-MPs after breaking the intestinal barrier and the effects caused. The collected data showed that PE-MPs accumulation for 21d altered the histomorphology and antioxidant enzyme activity of the intestine, induced dysbiosis of the intestinal flora. 10 mg/L of PE-MPs induced a significant increase in the transcript levels of intestinal immunity factors in loach after 21d of exposure. Moreover, the levels of diamine oxidase (DAO) and d-lactic acid (D-Lac) in the gut and serum of loach were significantly increased after exposure to PE-MPs at all concentrations (1, 5, 10 mg/L). Subsequently, the presence of PE-MPs was detected in the blood, suggesting that the disruption of the intestinal multilayer barrier allowed PE-MPs to spill into the circulation. The accumulation of PE-MPs (1,5,10 mg/L) in the blood led to massive apoptosis and necrosis of blood cells and activated phagocytosis in response to PE-MPs invasion. To alleviate the damage, this study further exposure the effect of probiotics on PE-MPs treated loach by adding Leuconostoc mesenteroides DH (109 CFU/g) to the feed. The results showed that DH significantly increased the intestinal index and reduced the levels of DAO and D-Lac. To investigate the reason, we followed the PE-MPs in the intestine and blood of the loach and found that the number of PE-MPs particles was significantly reduced in the probiotic group, while the PE-MPs content in the feces was elevated. Thus, we concluded that DH reducing the accumulation of PE-MPs in the intestinal by increases fecal PE-MPs, which in turn mitigates the damage to the intestinal barrier caused by PE-MPs, and reduces the amount of PE-MPs in the blood. This work offers a robust analysis to understand the mechanisms of damage to the intestinal barrier by MPs and the fate of MPs after escaping the intestinal barrier and provide a new perspective on the application of probiotics in mitigating PE-MPs toxicity.

Prevalence and molecular characteristics of Shewanella infection in diarrhea patients in Beijing, China 2017-2019

Introduction

Shewanella is an important opportunistic pathogen distributed in marine environments that has caused an increasing number of clinical infections. However, there are few reports on the distribution and characteristics of Shewanella in the diarrheal pathogen spectrum. In this study, we have systematically described the prevalence of Shewanella infections in diarrhea patients in Beijing, China 2017-2019, and genome characteristics and antimicrobial susceptibility of Shewanella isolates.

Methods

Stool samples were collected from diarrhea patients in a surveillance project from 2017 to 2019. Shewanella strains were isolated, and identified using VITEKR 2 COMPACT and MALDI-TOF MS. Average nucleotide identity (ANI) analysis, multi-locus sequence typing (MLST), phylogenetic analysis, virulence-associated genes and antimicrobial resistance genes analysis were used for genome characteristics description. The antibiotic susceptibility test was performed with microbroth dilution method.

Results

1104 fecal samples were collected, and the Shewanella detection rate was 2.36% (26/1104). The main manifestations of infection caused by Shewanella spp. were diarrhea (100%, 26/26), abdominal pain (65.38%, 17/26), and vomiting (38.46%, 10/26). The 26 isolates were classified into 3 species (S. algae (n = 18), S. indica (n = 5), and S. chilikensis (n = 3)) and 22 sequence types. Core genome single nucleotide polymorphism-based evolutionary tree identified three clone groups corresponding to three infection events in the same months in 2017 and 2019. The putative virulence-associated gene pool consisted of 56 potential virulence genes, including 19 virulence gene factors. The resistance rates of the 26 isolates to 17 antibiotics from high to low were as follows: polymyxin E (76.92%), cefotaxime (57.69%), ampicillin (50%), ampicillin-sulbactam (34.62%), nalidixic acid (15.38%), ciprofloxacin (11.54%), selectrin (3.846%,1/26), and tetracycline (3.846%, 1/26). The rate of multidrug resistance was 38.46% (10/26).

Discussion

Monitoring for Shewanella spp. should be added to the routine surveillance of infectious diarrhea during the epidemic season.

Longitudinal change of gut microbiota in hypertensive disorders in pregnancy: a nested case-control and Mendelian randomization study

Mounting evidence has shown that gut microbiota (GM) is related to hypertensive disorders in pregnancy (HDP), however, most studies only focused on one time point in pregnancy. In this study, we conducted a nested case-control study utilizing a follow-up cohort, resulting in the collection of 47 HDP patients and 30 healthy controls. The GM profiles were explored using 16S rRNA sequencing at three time points during pregnancy. The diversity analysis of GM showed no significant difference between HDP patients and controls, however, we found 21 differential GM during pregnancy. Trend analysis showed that there are statistical differences in the relative abundance of Thermomonas, Xanthomonas, and Phenylobacteriumat during pregnancy in the gestational hypertension group, and of Xanthomonas, Polycyclovorans, and Phenylobacterium in the control group. The correlation study found that six genera of GM are related to blood pressure. Furthermore, the MR analysis identified the causal relationship between Methanobrevibacter and pre-eclampsia (PE). This study first explored the longitudinal change of GM in HDP patients during pregnancy, found the differential GM, and detected the causal association. Our findings may promote the prevention and treatment of HDP from the perspective of GM and provide valuable insights into the pathogenesis of HDP.

Unveiling the Emergence and Genetic Diversity of OXA-48-like Carbapenemase Variants in Shewanella xiamenensis

An increase in the carbapenem-hydrolyzing capacity of class D β-lactamase has been observed in strains of multiple species, posing a significant challenge to the control of antibiotic resistance. In this study, we aimed to investigate the genetic diversity and phylogenetic characteristics of new bla_OXA-48-like variants derived from Shewanella xiamenensis. Three ertapenem-non-susceptible S. xiamenensis strains were identified, one isolated from the blood sample of an inpatient, the other two isolated from the aquatic environment. Phenotypic characterization confirmed that the strains were carbapenemase producers and exhibited antimicrobial resistance patterns to ertapenem, with some showing lower susceptibility to imipenem, chloramphenicol, ciprofloxacin, and tetracycline. No significant resistance to cephalosporins was observed. Sequence analysis revealed that one strain harbored bla_OXA-181 and the other two strains harbored bla_OXA-48-like genes, with open reading frame (ORF) similarities with bla_OXA-48 ranging from 98.49% to 99.62%. The two novel bla_OXA-48-like genes, named bla_OXA-1038 and bla_OXA-1039, respectively, were cloned and expressed in E. coli. The three OXA-48-like enzymes demonstrated significant hydrolysis activity against meropenem, and the classical β-lactamase inhibitor had no significant inhibitory effect. In conclusion, this study demonstrated the diversity of the bla_OXA gene and highlighted the emergence of novel OXA carbapenemases in S. xiamenensis. Further attention to S. xiamenensis and OXA carbapenemases is recommended for the effective prevention and control of antibiotic-resistant bacteria.

Characterizing sediment functional traits and ecological consequences respond to increasing antibiotic pollution

Current studies have shown that the taxonomic structures of ecologically important microbial communities are altered by antibiotic exposure, but the resulting effects on functional potentials and subsequent biogeochemical processes are poorly understood. However, this knowledge is indispensable for developing an accurate projection of nutrient dynamics in the future. Using metagenomic analyses, here we explored the responses of taxonomical and functional structures of a sediment microbial community, and their links with key biogeochemical processes to increasing antibiotic pollution from the pristine inlet to the outfall sites along an aquaculture discharge channel. We identified sharply contrasting sedimentary microbial communities and functional traits along increasing antibiotic pollution. Functional structures exhibited steeper distance-decay relationships than taxonomical structures along both the antibiotic distance and physicochemical distance, revealing higher functional sensitivity. Sediment enzyme activities were significantly and positively coupled with the relative abundances of their coding genes, thus the abundances of genes were indicative of functional potentials. The nitrogen cycling pathways were commonly inhibited by antibiotics, but not for the first step of nitrification, which could synergistically mitigate nitrous oxide emission. However, antibiotic pollution stimulated methanogens and inhibited methanotrophs, thereby promoting methane efflux. Furthermore, microbes could adapt to antibiotic pollution through enriched potential of sulfate uptake. Antibiotics indirectly affected taxonomic structures through alterations in network topological features, which in turn affected sediment functional structures and biogeochemical processes. Notably, only 13 antibiotics concentration-discriminatory genes contributed an overall 95.9% accuracy in diagnosing in situ antibiotic concentrations, in which just two indicators were antibiotic resistance genes. Our study comprehensively integrates sediment compositional and functional traits, biotic interactions, and enzymatic activities, thus generating a better understanding about ecological consequences of increasing antibiotics pollution. KEY POINTS: • Contrasting functional traits respond to increasing antibiotic pollution. • Antibiotics pollution stimulates CH₄ efflux, while mitigating N₂O emission and may drive an adaptive response of enriched sulfate uptake. • Indicator genes contribute 95.9% accuracy in diagnosing antibiotic concentrations.

Shewanella subflava sp. nov., a novel multi-resistant bacterium, isolated from the estuary of the Fenhe River into the Yellow River

A aerobic, gram-negative, rod-shaped and polar-flagellum bacterial strain, designated as FYR11-62^T, was isolated from the estuary of the Fenhe River into the Yellow River in Shanxi Province, China. The isolate was able to grow at 4-37 °C (optimum, 25 °C), pH 5.5-9.5 (optimum, pH 7.5) and in the presence of 0-7.0% (w/v) NaCl (optimum, 1.0% NaCl). Phylogenetic analyses based on 16S rRNA genes and 1597 single-copy orthologous clusters indicated that strain FYR11-62^T affiliated with the genus Shewanella and shared the highest 16S rRNA gene sequence similarity to Shewanella aestuarii SC18^T (98.3%) and Shewanella gaetbuli TF-27^T (97.3%), respectively. The major fatty acids were summed feature 3 (C_16:1 ω7c and/or C_16:1 ω6c), C_16:0 and iso-C_15:0. The major polar lipids were phosphatidylethanolamine and phosphatidylglycerol. The main quinones were Q-7 and Q-8. The genomic DNA G + C content was 41.6%. Gene annotation showed that strain FYR11-62^T possessed 30 antibiotic resistance genes, implying its multiple antidrug resistance. The average nucleotide identity and digital DNA-DNA hybridization values between strain FYR11-62^T and its closely related species were all below the thresholds for species delineation. The phylogenetic position together with the results of the analysis of morphological, physiological and genomic features support the classification of strain FYR11-62^T (= MCCC 1K07242^T = KCTC 92244^T) as a novel species of the genus Shewanella, for which the name Shewanella subflava sp. nov. is proposed.

An Insight into Goat Cheese: The Tales of Artisanal and Industrial Gidotyri Microbiota

The purpose of this study was to determine for the first time the microbiota in artisanal-type and industrial-type Gidotyri cheeses and investigate the influence of the cheese-making practices on their composition using culture-independent techniques. The microbiota present in artisanal with commercial starters (Artisanal_CS, n = 15), artisanal with in-house starters (Artisanal_IHS, n = 10) and industrial (Ind., n = 9) Gidotyri cheese samples were analyzed using a targeted metagenomic approach (16S rRNA gene). The Ind. Gidotyri cheese microbiota were less complex, dominated by the Streptococcaceae family (91%) that was more abundant compared to the artisanal Gidotyri cheeses (p < 0.05). Artisanal cheeses were more diverse compositionally with specific bacterial species being prevalent to each subtype. Particularly, Loigolactobacillus coryniformis (OTU 175), Secundilactobacillus malefermentans (OTU 48), and Streptococcus parauberis (OTU 50) were more prevalent in Artisanal_IHS cheeses compared to Artisanal_CS (p ≤ 0.001) and Ind. (p < 0.01) Gidotyri cheeses. Carnobacterium maltaromaticum (OTU 23) and Enterobacter hormaechei subsp. hoffmannii (OTU 268) were more prevalent in Artisanal_CS cheeses compared to Artisanal_IHS cheeses (p < 0.05) and Ind. cheeses (p < 0.05). Hafnia alvei (OTU 13) and Acinetobacter colistiniresistens (OTU 111) tended to be more prevalent in Artisanal_CS compared to the other two cheese groups (p < 0.10). In conclusion, higher microbial diversity was observed in the artisanal-type Gidotyri cheeses, with possible bacterial markers specific to each subtype identified with potential application to traceability of the manufacturing processes’ authenticity and cheese quality.

Comparative genome analysis of the genus Shewanella unravels the association of key genetic traits with known and potential pathogenic lineages

Shewanella spp. are Gram-negative rods widely disseminated in aquatic niches that can also be found in human-associated environments. In recent years, reports of infections caused by these bacteria have increased significantly. Mobilome and resistome analysis of a few species showed that they are versatile; however, comprehensive comparative studies in the genus are lacking. Here, we analyzed the genetic traits of 144 genomes from Shewanella spp. isolates focusing on the mobilome, resistome, and virulome to establish their evolutionary relationship and detect unique features based on their genome content and habitat. Shewanella spp. showed a great diversity of mobile genetic elements (MGEs), most of them associated with monophyletic lineages of clinical isolates. Furthermore, 79/144 genomes encoded at least one antimicrobial resistant gene with their highest occurrence in clinical-related lineages. CRISPR-Cas systems, which confer immunity against MGEs, were found in 41 genomes being I-E and I-F the more frequent ones. Virulome analysis showed that all Shewanella spp. encoded different virulence genes (motility, quorum sensing, biofilm, adherence, etc.) that may confer adaptive advantages for survival against hosts. Our data revealed that key accessory genes are frequently found in two major clinical-related groups, which encompass the opportunistic pathogens Shewanella algae and Shewanella xiamenensis together with several other species. This work highlights the evolutionary nature of Shewanella spp. genomes, capable of acquiring different key genetic traits that contribute to their adaptation to different niches and facilitate the emergence of more resistant and virulent isolates that impact directly on human and animal health.

Evolution of trimethoprim/sulfamethoxazole resistance in Shewanella algae from the perspective of comparative genomics and global phylogenic analysis

OBJECTIVE

Shewanella algae is a zoonotic marine bacterium that causes a variety of infections in immunocompromised patients or those who have been exposed to seawater. The development of trimethoprim/sulfamethoxazole (TMP/SMX) resistance in S. algae are found in human and environment isolates during the past ten years, and thus the treatment options are decreasing.

METHODOLOGY

In the study, we conduct a comparative genomic study to identify the resistant mechanism of TMP/SMX-resistance in S. algae.

RESULTS

We found the resistance of TMP/SMX in S. algae is associated with the existence of sul1 and dfrA12 within the class 1 integron. The gene cassette dfra12-aadA2-qacEΔ1/sul1 within the class 1 integron is highly conserved. In addition, the class 1 integron and encapsulated sul1 are significantly enriched in Enterobacteriaceae in NCBI and UniProt databases.

CONCLUSION

Our study suggests that the horizontal transfer of TMP/SMX resistance via class 1 integron is most frequently occurred within Enterobacteriaceae and has spread to a wide range of sources including soil, poultry, and marine water.

Shewanella infection in humans: Epidemiology, clinical features and pathogenicity

The genus Shewanella consists of Gram-negative proteobacteria that are ubiquitously distributed in environment. As the members of this genus have rapidly increased within the past decade, several species have become emerging pathogens worldwide, attracting the attention of the medical community. These species are also associated with severe community- and hospital-acquired infections. Patients infected with Shewanella spp. had experiences of occupational or recreational exposure; meanwhile, the process of infection is complex and the pathogenicity is influenced by a variety of factors. Here, an exhaustive internet-based literature search was carried out in PUBMED using terms “Achromobacter putrefaciens,” “Pseudomonas putrefaciens,” “Alteromonas putrefaciens” and “Shewanella” to search literatures published between 1978 and June 2022. We provided a comprehensive review on the epidemiology, clinical features and pathogenicity of Shewanella, which will contribute a better understanding of its clinical aetiology, and facilitate the timely diagnosis and effective treatment of Shewanella infection for clinicians and public health professionals.

Occurrence and Characterization of NDM-1-Producing Shewanella spp. and Acinetobacter portensis Co-Harboring tet(X3) in a Chinese Dairy Farm

Bacteria with carbapenem or tigecycline resistance have been spreading widely among humans, animals and the environment globally, being great threats to public health. However, bacteria co-carrying drug resistance genes of carbapenem and tigecycline in Shewanella and Acinetobacter species remain to be investigated. Here, we detected nine blaNDM-1-carrying Shewanella spp. isolates as well as three A. portensis isolates co-harboring tet(X3) and blaNDM-1 from seventy-two samples collected from a dairy farm in China. To explore their genomic characteristic and transmission mechanism, we utilized various methods, including PCR, antimicrobial susceptibility testing, conjugation experiment, whole-genome sequencing, circular intermediate identification and bioinformatics analysis. Clonal dissemination was found among three A. portensis, of which tet(X3) and blaNDM-1 were located on a novel non-conjugative plasmid pJNE5-X3_NDM-1 (333,311 bp), and the circular intermediate ΔISCR2-tet(X3)-blaNDM-1 was identified. Moreover, there was another copy of tet(X3) on the chromosome of A. portensis. It was verified that blaNDM-1 could be transferred to Escherichia coli C600 from Shewanella spp. by conjugation, and self-transmissible IncA/C2 plasmids mediated the transmission of blaNDM-1 in Shewanella spp. strains. Stringent surveillance was warranted to curb the transmission of such vital resistance genes.

Phage-prokaryote coexistence strategy mediates microbial community diversity in the intestine and sediment microhabitats of shrimp culture pond ecosystem

Emerging evidence supports that the phage-prokaryote interaction drives ecological processes in various environments with different phage life strategies. However, the knowledge of phage-prokaryote interaction in the shrimp culture pond ecosystem (SCPE) is still limited. Here, the viral and prokaryotic community profiles at four culture stages in the intestine of Litopenaeus vannamei and cultural sediment microhabitats of SCPE were explored to elucidate the contribution of phage-prokaryote interaction in modulating microbial communities. The results demonstrated that the most abundant viral families in the shrimp intestine and sediment were Microviridae, Circoviridae, Inoviridae, Siphoviridae, Podoviridae, Myoviridae, Parvoviridae, Herelleviridae, Mimiviridae, and Genomoviridae, while phages dominated the viral community. The dominant prokaryotic genera were Vibrio, Formosa, Aurantisolimonas, and Shewanella in the shrimp intestine, and Formosa, Aurantisolimonas, Algoriphagus, and Flavobacterium in the sediment. The viral and prokaryotic composition of the shrimp intestine and sediment were significantly different at four culture stages, and the phage communities were closely related to the prokaryotic communities. Moreover, the phage-prokaryote interactions can directly or indirectly modulate the microbial community composition and function, including auxiliary metabolic genes and closed toxin genes. The interactional analysis revealed that phages and prokaryotes had diverse coexistence strategies in the shrimp intestine and sediment microhabitats of SCPE. Collectively, our findings characterized the composition of viral communities in the shrimp intestine and cultural sediment and revealed the distinct pattern of phage-prokaryote interaction in modulating microbial community diversity, which expanded our cognization of the phage-prokaryote coexistence strategy in aquatic ecosystems from the microecological perspective and provided theoretical support for microecological prevention and control of shrimp culture health management.

Antibiotic resistant bacteria and genes in wastewater treatment plants: From occurrence to treatment strategies

This study aims to discuss the following: (1) occurrence and proliferation of antibiotic resistance in wastewater treatment plants (WWTPs); (2) factors influencing antibiotic resistance bacteria and genes in WWTPs; (3) tools to assess antibiotic resistance in WWTPs; (4) environmental contamination of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) from WWTPs; (5) effects of ARB and ARGs from WWTPs on human health; and (6) treatment strategies. In general, resistant and multi-resistant bacteria, including Enterobacteriaceae, Pseudomonas aeruginosa, and Escherichia coli, exist in various processes of WWTPs. The existence of ARB and ARGs results from the high concentration of antibiotics in wastewater, which promote selective pressures on the local bacteria present in WWTPs. Thus, improving wastewater treatment technology and avoiding the misuse of antibiotics is critical to overcoming the threat of proliferation of ARBs and ARGs. Numerous factors can affect the development of ARB and ARGs in WWTPs. Abiotic factors can affect the bacterial community dynamics, thereby, affecting the applicability of ARB during the wastewater treatment process. Furthermore, the organic loads and other nutrients influence bacterial survival and growth. Specifically, molecular methods for the rapid characterization and detection of ARBs or their genes comprise DNA sequencing, real-time PCR, simple and multiplex PCR, and hybridization-based technologies, including micro- and macro-arrays. The reuse of effluent from WWTPs for irrigation is an efficient method to overcome water scarcity. However, there are also some potential environmental risks associated with this practice, such as increase in the levels of antibiotic resistance in the soil microbiome. Human mortality rates may significantly increase, as ARB can lead to resistance among several types of antibiotics or longer treatment times. Some treatment technologies, such as anaerobic and aerobic treatment, coagulation, membrane bioreactors, and disinfection processes, are considered potential techniques to restrict antibiotic resistance in the environment.

A Pilot Study: Favorable Effects of Clostridium butyricum on Intestinal Microbiota for Adjuvant Therapy of Lung Cancer

Probiotics as medications have previously been shown to change intestinal microbial characteristics, potentially influencing cancer therapy efficacy. Patients with non-squamous non-small cell lung cancer (NS-NSCLC) treated by bevacizumab plus platinum-based chemotherapy were randomized to obtain Clostridium butyricum supplement (CBS) or receive a placebo as adjuvant therapy. Clinical efficacy and safety were assessed using progression-free survival (PFS), overall survival (OS), and adverse events (AE). Intestinal microbiota was longitudinally explored between CBS and placebo groups over time. Patients who took CBS had significantly decreased bacterial richness and abundance, as well as increased the total richness of the genus Clostridium, Bifidobacterium, and Lactobacillus compared to the placebo group (p < 0.05). Beta diversity and the interactional network of intestinal microbiota were distinctly different between CBS and placebo group. However, there were no significant variations between them in terms of microbial taxonomical taxa and alpha diversity. The potential opportunistic pathogen Shewanella was still detectable after treatment in the placebo group, while no distinguishing microbial markers were found in the CBS group. In terms of clinical efficacy, the CBS group had a significantly reduced AE compare to the placebo group (p < 0.05), although no significantly longer PFS and OS. Therefore, favorable modifications in intestinal microbiota and significant improvements in drug safety make probiotics be promising adjunctive therapeutic avenues for lung cancer treatment.

Novel Mobile Integrons and Strain-Specific Integrase Genes within Shewanella spp. Unveil Multiple Lateral Genetic Transfer Events within The Genus

Shewanella spp. are Gram-negative bacteria that thrive in aquatic niches and also can cause infectious diseases as opportunistic pathogens. Chromosomal (CI) and mobile integrons (MI) were previously described in some Shewanella isolates. Here, we evaluated the occurrence of integrase genes, the integron systems and their genetic surroundings in the genus. We identified 22 integrase gene types, 17 of which were newly described, showing traits of multiple events of lateral genetic transfer (LGT). Phylogenetic analysis showed that most of them were strain-specific, except for Shewanella algae, where SonIntIA-like may have co-evolved within the host as typical CIs. It is noteworthy that co-existence of up to five different integrase genes within a strain, as well as their wide dissemination to Alteromonadales, Vibrionales, Chromatiales, Oceanospirillales and Enterobacterales was observed. In addition, identification of two novel MIs suggests that continuous LGT events may have occurred resembling the behavior of class 1 integrons. The constant emergence of determinants associated to antimicrobial resistance worldwide, concomitantly with novel MIs in strains capable to harbor several types of integrons, may be an alarming threat for the recruitment of novel antimicrobial resistance gene cassettes in the genus Shewanella, with its consequent contribution towards multidrug resistance in clinical isolates.

Microbial Landscape and Antibiotic Susceptibility Dynamics of Skin and Soft Tissue Infections in Kazakhstan 2018–2020

Skin and soft tissue inflammatory diseases of bacterial origin occupy a significant part of hospitalizations to emergency departments. One of the most common causes of sepsis is soft tissue infection, which accounts for about a quarter of all nosocomial infections. The aim of this study was to determine the differences in microbial landscape and antibiotic susceptibility of soft tissue infection pathogens among adults and children during the period 2018–2020. We studied 110 samples of pus admitted to the Scientific Research laboratory of the Karaganda Medical University from 2018 to 2020. Each sample was studied using the standard and express methods. The antibiotic susceptibility was determined by using the diffuse disk method in accordance with the CLSI 2018 recommendations. As such, 50% of S. epidermidis strains in children and 30% in adults were methicillin resistant. Differences in the resistance of S. aureus strains in children and adults were insignificant. Thus, methicillin-resistant S. aureus (MRSA) was not detected in children, but in adults, on the other hand, their percentage was 12.5%. The third cause of infection in adults was E. coli (13.72%), among which 75% were multidrug resistant. A. baumanii was found in 4.9% of adult patients’ samples, of which 60% were multidrug resistant. The effectiveness of the most prescribed antibiotics decreased due to the isolated strain resistance.

The Fulminating Course of Infection Caused by Shewanella algae: A Case Report

Shewanella algae, a Gram-negative bacillus found in warm saltwater environments, has been increasingly recognized as a human pathogen that can cause infection of the skin and soft tissue, ear, blood, and intra-abdominal. In this case, we report a Shewanella algae infection that caused sepsis, renal insufficiency, cardiac dysfunction, fistula and massive pleural effusion after surgery in a 73-year-old man with cancer of the esophagus and cardia.

Complete genome sequence of Shewanella algae strain 2NE11, a decolorizing bacterium isolated from industrial effluent in Peru

Shewanella is a microbial group with high potential to be applied in textile effluents bioremediation due to its ability to use a wide variety of substrates as a final electron acceptor in respiration. The present research aimed to describe a new strain, Shewanella algae 2NE11, a decolorizing bacterium isolated from industrial effluent in Peru. S. algae 2NE11 showed an optimal growth under pH 6-9, temperature between 30-40 °C, and 0-4 % NaCl. It can tolerate high concentrations of NaCl until 10% and low temperatures as 4 °C. It decolorizes azo and anthraquinone dyes with a decolorization rate of 89-97%. We performed next-generation sequencing (Pacific Bioscience®) and achieved its complete genome sequence with a length of 5,030,813bp and a GC content of 52.98%. Genomic characterization revealed the presence of protein-coding genes related to decolorization like azoreductase, dyp-peroxidase, oxidoreductases, and the complete Mtr respiratory pathway. Likewise, we identified other properties such as the presence of metal resistant genes, and genes related to lactate and N-acetylglucosamine metabolism. These results highlight its potential to be applied in the bioremediation of textile effluents and guide future research on decolorization metabolic pathways.

Shewanella jiangmenensis sp. nov., isolated from aquaculture water

A Gram-stain-negative and facultatively anaerobic bacterial strain designated as JM162201^T was isolated from aquaculture water for farming Pacific white shrimp (Litopenaeus vannamei). The genome size of strain JM162201^T was 4,436,316 bp, and the genomic DNA G + C content was 55.0%. Phylogenetic analysis based on 16S rRNA gene sequences and genomes showed that strain JM162201^T belonged to the genus Shewanella and was closely related to Shewanella litorisediminis SMK1-12^T (97.1%), Shewanella khirikhana TH2012^T (97.0%), and Shewanella amazonensis SB2B^T (96.0%). The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain JM162201^T and three reference type strains were below the recognized thresholds of 95.0-96.0% (for ANI) and 70.0% (for dDDH) for species delineation. Growth occurred at 10-40 °C (optimum, 30 °C), at pH 4.0-10.0 (optimum, 7.0-8.0), and in 0-6.0% NaCl (w/v, optimum, 0-0.1%). The major cellular fatty acids of strain JM162201^T were summed feature 3 (C_16:1 ω7c and/or C_16:1 ω6c), C_17:1 ω8c, iso-C_15:0, C_16:0, and C_15:0. The predominant quinones were MK7, Q-7, and Q-8. The major polar lipids were phosphatidylethanolamine (PE) and phosphatidylglycerol (PG). Based on the polyphasic taxonomical analyses, strain JM162201^T represents a novel species of the genus Shewanella, for which the name Shewanella jiangmenensis sp. nov. is proposed, with the type strain JM162201^T (= GDMCC 1.2006^T = KCTC 82340^T).

Molecular identification and antibiotic resistance patterns of diverse bacteria associated with shrimp PL nurseries of Bangladesh: suspecting Acinetobacter venetianus as future threat

Shrimp aquaculture has been accomplished with breeding and nursing of shrimp in an artificial environment to fulfill the increasing demand of shrimp consumption worldwide. However, the microbial diseases appear as a serious problem in this industry. The study was designed to identify the diverse bacteria from shrimp PL (post-larvae) nurseries and to profile antibiotic resistance patterns. The rearing water (raw seawater, treated and outlet water) and shrimp PL were collected from eight nurseries of south-west Bangladesh. Using selective agar plates, thirty representative isolates were selected for 16S rRNA gene sequencing, antibiotic susceptibility test and MAR index calculation. Representative isolates were identified as Aeromonas caviae, Pseudomonas monteilii, Shewanella algae, Vibrio alginolyticus, V. brasiliensis, V. natriegens, V. parahaemolyticus, V. shilonii, V. xuii, Zobellella denitrificans which are Gram-negative, and Bacillus licheniformis and B. pumilus which are Gram-positive. Notably, six strains identified as Acinetobacter venetianus might be a concern of risk for shrimp industry. The antibiotic resistance pattern reveals that the strain YWO8-97 (identified as P. monteilii) was resistant to all twelve antibiotics. Ceftazidime was the most powerful antibiotic since most of the studied strains were sensitive against it. The six strains of A. venetianus showed multiple antibiotic resistance patterns. MAR index were ranged from 0.08 to 1.0, and values of 26 isolates were more than 0.2 which means prior high exposure to the antibiotics. From the present study, it can be concluded that shrimp PL nurseries in southern part of Bangladesh are getting contaminated with antibiotic resistant pathogenic bacteria.

Genomic analysis reveals high intra-species diversity of Shewanella algae

Shewanella algae is widely distributed in marine and freshwater habitats, and has been proved to be an emerging marine zoonotic and human pathogen. However, the genomic characteristics and pathogenicity of Shewanella algae are unclear. Here, the whole-genome features of 55 S. algae strains isolated from different sources were described. Pan-genome analysis yielded 2863 (19.4 %) genes shared among all strains. Functional annotation of the core genome showed that the main functions are focused on basic lifestyle such as metabolism and energy production. Meanwhile, the phylogenetic tree of the single nucleotide polymorphisms (SNPs) of core genome divided the 55 strains into three clades, with the majority of strains from China falling into the first two clades. As for the accessory genome, 167 genomic islands (GIs) and 65 phage-related elements were detected. The CRISPR-Cas system with a high degree of confidence was predicted in 23 strains. The GIs carried a suite of virulence genes and mobile genetic elements, while prophages contained several transposases and integrases. Horizontal genes transfer based on homology analysis indicated that these GIs and prophages were parts of major drivers for the evolution and the environmental adaptation of S. algae. In addition, a rich putative virulence-associated gene pool was found. Eight classes of antibiotic-associated resistance genes were detected, and the carriage rate of β-lactam resistance genes was 100 %. In conclusion, S. algae exhibits a high intra-species diversity in the aspects of population structure, virulence-associated genes and potential drug resistance, which is helpful for its evolution in pathogenesis and environmental adaptability.

Intestinal morphology and microflora to Vibrio alginolyticus in pacific white shrimp (Litopenaeus vannamei)

In recent years, the shrimp farming industry encountered significant economic losses induced by Vibrio alginolyticus. In this study, the influence of Vibrio alginolyticus on intestinal histomorphology and microbiome composition in Litopenaeus vannamei were studied. The results showed that the intestinal mucosal epithelial cells of Vibrio group (VA group) injected only with Vibrio alginolyticus showed large area exfoliation at 12 h, and the tissue morphology of intestine recovered at 48 h. Compared with the control group (CK group), the abundance of Proteobacteria was significantly higher (P < 0.05), while the abundance of Actinobacteria was significantly lower after infection with Vibrio alginolyticus. The abundance of Shewanella in intestinal microbiome of Litopenaeus vannamei was significantly higher at 12 h (P < 0.05), but the abundance of Candidatus_Bacilloplasma was significantly lower at 48 h after infection (P < 0.05). In VA group, the diversity of intestinal microbiome was significantly lower at 12 h, which could be caused by the proliferation of Candidatus_Bacilloplasma and Shewanella. All above findings suggested that the stability of the dynamic balance of microbiome in the intestine helped Litopenaeus vannamei to resist pathogen colonization.

Metagenomic and Recombination Analyses of Antimicrobial Resistance Genes from Recreational Waters of Black Sea Coastal Areas and Other Marine Environments Unveil Extensive Evidence for Their both Intrageneric and Intergeneric Transmission across Genetically Very Diverse Microbial Communities

Microbial communities of marine coastal recreation waters have become large reservoirs of AMR genes (ARGs), contributing to the emergence and transmission of various zoonotic, foodborne and other infections that exhibit resistance to various antibiotics. Thus, it is highly imperative to determine ARGs assemblages as well as mechanisms and trajectories of their transmission across these microbial communities for our better understanding of the evolutionary trends of AMR (AMR). In this study, using metagenomics approaches, we screened for ARGs in recreation waters of the Black Sea coastal areas of the Batumi City (Georgia). Also, a large array of the recombination detection algorithms of the SplitsTree, RDP4, and GARD was applied to elucidate genetic recombination of ARGs and trajectories of their transmission across various marine microbial communities. The metagenomics analyses of sea water samples, obtained from across the above marine sites, could identify putative ARGs encoding for multidrug resistance efflux transporters mainly from the Major Facilitator and Resistance Nodulation Division superfamilies. The data, generated by SplitsTree (fit ≥95.619; bootstrap values ≥ 95; Phi p ≤ 0.0494), RDP4 (p ≤ 0.0490), and GARD, provided strong statistical evidence not only for intrageneric recombination of these ARGs, but also for their intergeneric recombination across fairly large and diverse microbial communities of marine environment. These bacteria included both human pathogenic and nonpathogenic species, exhibiting collectively the genera of Vibrio, Aeromonas, Synechococcus, Citromicrobium, Rhodobacteraceae, Pseudoalteromonas, Altererythrobacter, Erythrobacter, Altererythrobacter, Marivivens, Xuhuaishuia, and Loktanella. The above nonpathogenic bacteria are strongly suggested to contribute to ARGs transmission in marine ecosystems.

Disruption of Intestinal Homeostasis Through Altered Responses of the Microbial Community, Energy Metabolites, and Immune System in Zebrafish After Chronic Exposure to DEHP

Di-(2-ethylhexyl) phthalate (DEHP) is ubiquitously reported in global water bodies and exhibits various environmental and human health risks. However, the effects of DEHP chronic exposure on the intestinal microbiota and associated host health concerns in aquatic species are still largely unexplored. In this study, chronic exposure to DEHP at environmental levels significantly increased the body weight, length, and body mass index (BMI), especially in male fish. The microbial community was disrupted with the relative abundance of phylum Firmicutes and genera diversity for Prevotella-7, Deefgea, PeM15, Halomonas, Akkermansia, Chitinibacter, and Roseomonas, which are significantly activated in zebrafish after exposure to DEHP. The height of the gut villus, the thickness of muscularis layer, and the number of goblet cells per villus were significantly decreased, as well as showed differences between female and male zebrafish. Further, the levels of energy-related metabolites in gut tissues were increased, compared to the control group. The expression levels of immune-related genes (interleukin 8, il-8, also referred to as cxcl8a), microbial defense-related genes (lysozyme, lyz, interleukin 10, and il-10), and obesity-related genes (aquaporin 8a, aqp8, mucin 2.1, muc2.1, fibroblast growth factor 2, fgf2, and proopiomelanocortin a, pomca) were significantly up-regulated in zebrafish, except the down-regulated expressions of toll-like receptor-5 (tlr-5) and interleukin 1β (il-1β) in the females and pomca in the males, respectively. Importantly, Spearman's correlation analyses revealed that the levels of metabolites and gene expressions in the gut were closely related to the dominant microbial genera, such as Aeromonas, Deefgea, Akkermansia, PeM15, Mycobacterium, and Rhodobacter. Taken together, chronic exposure to DEHP at environmental levels disturbed bacterial composition accompanied by the altered expressions of intestinal metabolites and the critical immune and intestinal function-related genes, which provided novel insights into DEHP effects on perturbation of gut microbiota and metabolic homeostasis in zebrafish.

Coming from the Wild: Multidrug Resistant Opportunistic Pathogens Presenting a Primary, Not Human-Linked, Environmental Habitat

The use and misuse of antibiotics have made antibiotic-resistant bacteria widespread nowadays, constituting one of the most relevant challenges for human health at present. Among these bacteria, opportunistic pathogens with an environmental, non-clinical, primary habitat stand as an increasing matter of concern at hospitals. These organisms usually present low susceptibility to antibiotics currently used for therapy. They are also proficient in acquiring increased resistance levels, a situation that limits the therapeutic options for treating the infections they cause. In this article, we analyse the most predominant opportunistic pathogens with an environmental origin, focusing on the mechanisms of antibiotic resistance they present. Further, we discuss the functions, beyond antibiotic resistance, that these determinants may have in the natural ecosystems that these bacteria usually colonize. Given the capacity of these organisms for colonizing different habitats, from clinical settings to natural environments, and for infecting different hosts, from plants to humans, deciphering their population structure, their mechanisms of resistance and the role that these mechanisms may play in natural ecosystems is of relevance for understanding the dissemination of antibiotic resistance under a One-Health point of view.

Establishment and Application of Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry for Detection of Shewanella Genus

Shewanella species are widely distributed in the aquatic environment and aquatic organisms. They are opportunistic human pathogens with increasing clinical infections reported in recent years. However, there is a lack of a rapid and accurate method to identify Shewanella species. We evaluated here matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for rapid identification of Shewanella. A peptide mass reference spectra (PMRS) database was constructed for the type strains of 36 Shewanella species. The main spectrum projection (MSP) cluster dendrogram showed that the type strains of Shewanella species can be effectively distinguished according to the different MS fingerprinting. The PMRS database was validated using 125 Shewanella test strains isolated from various sources and periods; 92.8% (n = 116) of the strains were correctly identified at the species level, compared with the results of multilocus sequence analysis (MLSA), which was previously shown to be a method for identifying Shewanella at the species level. The misidentified strains (n = 9) by MALDI-TOF MS involved five species of two groups, i.e., Shewanella algae-Shewanella chilikensis-Shewanella indica and Shewanella seohaensis-Shewanella xiamenensis. We then identified and defined species-specific biomarker peaks of the 36 species using the type strains and validated these selected biomarkers using 125 test strains. Our study demonstrated that MALDI-TOF MS was a reliable and powerful tool for the rapid identification of Shewanella strains at the species level.

Comparative genomics of two Shewanella xiamenensis strains isolated from a pilgrim before and during travels to the Hajj

BACKGROUND

Shewanella xiamenensis has been reported in water environment and in patients and can act as the originator of oxacillinase in gram-negative bacteria. In order to assess genome plasticity and its functional properties related diarrhea symptoms in pilgrim, comparisons of draft genome sequences of the two isolates were conducted with other closely related genomes.

RESULTS

We isolated S. xiamenensis 111B and 111D strains from a pilgrim before travels to the Hajj and during travels with diarrhea symptom, respectively. Whole-genome sequencing showed that draft genome size of 111B strain was 5,008,191 bp, containing 49 kb of a putative plasmid. The genome size of 111D was 4,964,295 bp containing 225 kb of a putative plasmid that shared the backbone sequences with the hospital wastewater strain T17. Comparatively, two Hajj strains are identical at 97.3% identity and 98.7% coverage. They are closely related to river water strain, AS58 by SNPs analysis. Notably, a novel bla_OXA-48 allele bla_OXA-547 was identified in 111D, sharing 99.5% identity with bla_OXA-546 and bla_OXA-894. Multiple copies of virulence specific genes, such as capsular polysaccharide biosynthesis, O-antigen and lasB (vibriolysin related gene) have been identified specifically in 111D, but absent in 111B strain.

CONCLUSIONS

The whole genome sequences of S. xiamenensis strain 111B and 111D, including comparative genomic analysis, highlight here the potential for virulence factors that might be related to the cause of diarrhea in humans and also indicate the possible acquisition of pathogenic bacteria, including antibiotic resistance genes or plasmids during the Hajj.

Non-Necrotizing Bullous Cellulitis and Bacteremia: A Rare Presentation of the Shewanella Algae Infection

A 58-year-old male with severe psoriasis on Risankizumab presented with painful, left leg swelling with erythema and blisters concerning for necrotizing fasciitis. Intraoperative findings showed non-necrotizing bullous cellulitis. The blood and tissue cultures grew Shewanella algae. A handful case of non-necrotizing bullous cellulitis has been reported but this is the first documented case of non-necrotizing bullous cellulitis and bacteremia in PubMed.

Searching for putative virulence factors in the genomes of Shewanella indica and Shewanella algae

Bacterial pathogens are a major threat to both humans and animals worldwide. It is crucial to understand the mechanisms of various disease processes at the molecular level. Shewanella species are widespread in the environment and some are considered as emerging opportunistic human and marine mammal pathogens. In this study, putative virulence factors on the genome of Shewanella indica BW, a bacterium isolated from the Bryde's whale (Balaenoptera edeni), were determined. Additionally, for comparative purposes, putative virulence factors from two other S. indica and ten S. algae strains were also determined using the Pathosystems Resource Integration Center (PATRIC) pipeline. We confirmed the presence of previously reported virulence factors and we are proposing several new candidate virulence factors. Interestingly, the putative virulence factors were very similar between the two species with the exception of microbial collagenase which was present in all S. algae genomes, but absent in all S. indica genomes.

Isolation and Characterization of Shewanella Phage Thanatos Infecting and Lysing Shewanella oneidensis and Promoting Nascent Biofilm Formation

Species of the genus Shewanella are widespread in nature in various habitats, however, little is known about phages affecting Shewanella sp. Here, we report the isolation of phages from diverse freshwater environments that infect and lyse strains of Shewanella oneidensis and other Shewanella sp. Sequence analysis and microscopic imaging strongly indicate that these phages form a so far unclassified genus, now named Shewanella phage Thanatos, which can be positioned within the subfamily of Tevenvirinae (Duplodnaviria; Heunggongvirae; Uroviricota; Caudoviricetes; Caudovirales; Myoviridae; Tevenvirinae). We characterized one member of this group in more detail using S. oneidensis MR-1 as a host. Shewanella phage Thanatos-1 possesses a prolate icosahedral capsule of about 110 nm in height and 70 nm in width and a tail of about 95 nm in length. The dsDNA genome exhibits a GC content of about 34.5%, has a size of 160.6 kbp and encodes about 206 proteins (92 with an annotated putative function) and two tRNAs. Out of those 206, MS analyses identified about 155 phage proteins in PEG-precipitated samples of infected cells. Phage attachment likely requires the outer lipopolysaccharide of S. oneidensis, narrowing the phage's host range. Under the applied conditions, about 20 novel phage particles per cell were produced after a latent period of approximately 40 min, which are stable at a pH range from 4 to 12 and resist temperatures up to 55°C for at least 24 h. Addition of Thanatos to S. oneidensis results in partial dissolution of established biofilms, however, early exposure of planktonic cells to Thanatos significantly enhances biofilm formation. Taken together, we identified a novel genus of Myophages affecting S. oneidensis communities in different ways.

Comparative genomics reveals insights into characterization and distribution of quorum sensing-related genes in Shewanella algae from marine environment and clinical sources

Shewanella algae is not only the most commonly reported species in Shewanella human infections but also capable to inhabit a wide variety of habitats. Although there is evidence that quorum sensing is associated with bacterial adaptation to changing environmental conditions, little is known of the quorum sensing system in S. algae. In this study, we conducted the whole genome sequencing of S. algae strains and applied comparative genomics to reveal the core genome. Genes related to the quorum sensing system were identified by integrated bioinformatics analysis. S. algae harbor genes involved in all three main types of autoinducer systems. This study provides insights into the quorum sensing systems in S. algae, which might be valuable in the future study of cell behavior in S. algae.

Shewanella harboring antimicrobial and copper resistance genes in sea urchins (Paracentrotus lividus) from the Crozon peninsula (Brittany, France)

Shewanella is a genus of aquatic non-fermenting Gram-negative bacteria with increasing numbers of reports of infections in humans and appearance of antimicrobial resistant strains. Cases of infection show a relatively strong association with seafood consumption or exposure to seawater. This study aimed to analyze Shewanella spp. isolated from the sea urchin Paracentrotus lividus collected from the Crozon peninsula (France) with the intention of obtaining insights into the role of this genus as a reservoir of antimicrobial and heavy metal resistance genes. Five among seven Shewanella isolates were resistant to antimicrobials, mainly to broad spectrum beta-lactams. Four isolates displayed multiple resistance to at least three of these antimicrobial classes: broad spectrum beta-lactams, aminoglycosides, macrolide, quinolones and/or tetracycline. Three antimicrobial resistance genes were detected in just one isolate encoding resistance to beta-lactam (bla_SHV and bla_TEM-1) and macrolide (ermB). In addition, the copper resistance gene cusB, was observed in this isolate which is also a plasmid carrier. Another copper resistance encoding gene, copA, was found among the isolates. These results indicate that the multidrug-resistant (MDR) Shewanella isolates and resistance genes could be potential risks to public health, due to the carrying of these MDR bacteria by sea urchins through human consumption.

Droplet-based high-throughput cultivation for accurate screening of antibiotic resistant gut microbes

Traditional cultivation approaches in microbiology are labor-intensive, low-throughput, and yield biased sampling of environmental microbes due to ecological and evolutionary factors. New strategies are needed for ample representation of rare taxa and slow-growers that are often outcompeted by fast-growers in cultivation experiments. Here we describe a microfluidic platform that anaerobically isolates and cultivates microbial cells in millions of picoliter droplets and automatically sorts them based on colony density to enhance slow-growing organisms. We applied our strategy to a fecal microbiota transplant (FMT) donor stool using multiple growth media, and found significant increase in taxonomic richness and larger representation of rare and clinically relevant taxa among droplet-grown cells compared to conventional plates. Furthermore, screening the FMT donor stool for antibiotic resistance revealed 21 populations that evaded detection in plate-based assessment of antibiotic resistance. Our method improves cultivation-based surveys of diverse microbiomes to gain deeper insights into microbial functioning and lifestyles.

Detection of S83V GyrA mutation in quinolone-resistant Shewanella algae using comparative genomics

BACKGROUND

Shewanella algae is a zoonotic pathogen that poses a serious health threat to immunocompromised hosts. Treatment of S. algae infections is challenging due to the pathogen's intrinsic resistance to a variety of β-lactam antibiotics. Therapeutic options have become further limited by the emergence of quinolone-resistant strains. Currently, there are few studies concerning the genetic and molecular mechanisms underlying acquired quinolones resistance in S. algae. qnrA was once proposed as the candidate gene related to quinolones resistance in S. algae. However, recent studies demonstrated qnrA are highly conservative and does not confer resistance to quinolones in S. algae.

METHODS

A total of 27 non-duplicated isolates of S. algae strains were examined. MICs of ciprofloxacin were determined using Vitek 2. Whole genome sequencing was performed using MiSeq platform. Comprehensive Antibiotic Resistance Database and ResFinder were used for annotation of quinolones resistance genes. Multiple sequence alignment by EMBOSS Clustal Omega were used to identified mutation in quinolone resistance-determining regions. To investigation of the alteration of protein structure induced by mutation, in silico molecular docking studies was conducted using Accryl Discovery studio visualizer.

RESULTS

All S. algae harbored the quinolone-resistance associated genes (qnrA, gyrA, gyrB, parC, and parE) regardless its resistance to ciprofloxacin. Comparison of these genomes identified a nonsynonymous mutation (S83V) in chromosome-encoded gyrase subunits (GyrA) in quinolone-resistant strain. We found this mutation disrupts the water-metal ion bridge, reduces the affinity of the quinolone-enzyme complex for the metal ions and therefore decrease the capability of quinolones to stabilize cleavage complexes.

CONCLUSIONS

The study provides insight into the quinolone resistance mechanisms in S. algae, which would be helpful for the evolution of antibiotic resistance in this bacterium.

Shewanella khirikhana sp. nov. - a shrimp pathogen isolated from a cultivation pond exhibiting early mortality syndrome

Early mortality syndrome (EMS) in cultivated shrimp is of complex aetiology. One of the causes is acute hepatopancreatic necrosis disease (AHPND) caused by unique Vibrio isolates that carry two Pirvp toxin genes, but other causes of EMS remain mostly unexplained. Here, we describe the discovery of a Shewanella isolate TH2012T from an EMS/AHPND outbreak pond and demonstrate its virulence for shrimp (the mean lethal concentration of 105 colony-forming units per millilitre by immersion challenge) accompanied by distinctive histopathology, particularly of the ventral nerve cord and lymphoid organ but also including the digestive tract. On the basis of its complete genome sequence, multilocus phylogenetic trees, digital DNA-DNA hybridization analysis and differential phenotypic characteristics, we propose that Shewanella isolate TH2012T represents a novel species, separated sufficiently from the type strains S. litorisediminis and S. amazonensis to justify naming it Shewanella khirikhana sp. nov. Analysis of the TH2012T genome revealed no homologues of the Pirvp toxin genes but revealed a number of other potential virulence factors. It constitutes the first Shewanella isolate reported to be pathogenic to shrimp.

Shewanella algae and Vibrio spp. strains isolated in Italian aquaculture farms are reservoirs of antibiotic resistant genes that might constitute a risk for human health

The aquatic environment can represent a reservoir of antimicrobial resistance genes. In the present study, phenotypical, biochemical and molecular techniques were used to screen a collection of marine strains isolated in Italian aquaculture farms to investigate their beta-lactam resistance profiles. The genome of 12 carbapenemase and/or beta-lactamase producing strains was sequenced and a phylogenetic analysis of the beta-lactamases found in their chromosomes was performed. Gene annotation and prediction revealed the presence of bla_AmpC and bla_OXA-55-like in all the Shewanella algae isolates whereas in Vibrio anguillarum and Vibrio parahaemolyticus strains, bla_AmpC and bla_CARB-19 were found, respectively. Multiple alignments of OXA-55-like and AmpC protein sequences showed different point mutations. Finally, comparisons between enzyme phylogeny and strain clusterization based on sampling sites and dates indicate the diffusion of specific Multi Drug Resistant (MDR) Shewanella algae clones along the Italian Adriatic coast.

Resistome, Mobilome and Virulome Analysis of Shewanella algae and Vibrio spp. Strains Isolated in Italian Aquaculture Centers

Antimicrobial resistance is a major public health concern restricted not only to healthcare settings but also to veterinary and environmental ones. In this study, we analyzed, by whole genome sequencing (WGS) the resistome, mobilome and virulome of 12 multidrug-resistant (MDR) marine strains belonging to Shewanellaceae and Vibrionaceae families collected at aquaculture centers in Italy. The results evidenced the presence of several resistance mechanisms including enzyme and efflux pump systems conferring resistance to beta-lactams, quinolones, tetracyclines, macrolides, polymyxins, chloramphenicol, fosfomycin, erythromycin, detergents and heavy metals. Mobilome analysis did not find circular elements but class I integrons, integrative and conjugative element (ICE) associated modules, prophages and different insertion sequence (IS) family transposases. These mobile genetic elements (MGEs) are usually present in other aquatic bacteria but also in Enterobacteriaceae suggesting their transferability among autochthonous and allochthonous bacteria of the resilient microbiota. Regarding the presence of virulence factors, hemolytic activity was detected both in the Shewanella algae and in Vibrio spp. strains. To conclude, these data indicate the role as a reservoir of resistance and virulence genes in the environment of the aquatic microbiota present in the examined Italian fish farms that potentially might be transferred to bacteria of medical interest.

Comparative Genomics Reveals Pathogenicity-Related Loci in Shewanella algae

Shewanella algae is an emerging marine zoonotic pathogen and accounts for considerable mortality and morbidity in compromised hosts. However, there is scarce literature related to the understanding of the genetic background of virulence determinants in S. algae. In this study, we aim to determine the occurrence of common virulence genes in S. algae using whole-genome sequence and comparative genomic analysis. Comparative genomics reveals putative-virulence genes related to bile resistance, chemotaxis, hemolysis, and motility. We detected the existence of hlyA, hlyD, and hlyIII involved in hemolysis. We also found chemotaxis gene cluster cheYZA operon and cheW gene. The results provide insights into the genetic basis underlying pathogenicity in S. algae.

Molecular Characterization of Circulating Microbiome Signatures in Rheumatoid Arthritis

Rheumatoid Arthritis (RA) has been increasingly associated with perturbations to the microbial communities that reside in and on the body (the microbiome), in both human and animal studies. To date, such studies have mainly focused on the microbial communities that inhabit the gut and oral cavity. Mounting evidence suggests that microbial DNA can be detected in the blood circulation using a range of molecular methods. This DNA may represent an untapped pool of biomarkers that have the potential to report on changes to the microbiome of distant sites (e.g., example, the gut and oral cavity). To this end, through amplification and sequencing of the bacterial 16S rRNA variable region four, we evaluated the presence and identity of microbial DNA in blood samples obtained from RA patients (both prior to and 3 months following the instigation of treatment) in comparison to a small number of healthy control subjects and samples obtained from patients with ankylosing spondylitis (AS) and psoriatic arthritis (PA). Bacterial-derived DNA was identified in the majority of our patient samples. Taxonomic classification revealed that the microbiome community in RA was distinct from AS, PA, and the healthy state. Through analysis of paired patient samples obtained prior to and 3 months following treatment (V0 vs. V3), we found the microbiome to be modulated by treatment, and in many cases, this shift reduced the distance between these samples and the healthy control samples, suggesting a partial normalization following treatment in some patients. This effect was especially evident in seronegative arthritis patients. Herein, we provide further evidence for the existence of a blood microbiome in health and identify specific taxa modulated in disease and following treatment. These blood-derived signatures may have significant utility as disease biomarkers and suggest this area warrants further investigation.

Shewanella algae Infections in United States Naval Special Warfare Trainees

Shewanella infections are uncommon in immunocompetent hosts. We report 6 cases of Shewanella algae infection in young, healthy Naval Special Warfare trainees in San Diego during 2 consecutive El Niño seasons, defining a unique population at risk and adding to the epidemiologic understanding of this potentially virulent organism.

A rare case of Shewanella septicemia: risk factors, environmental associations and management

Shewanella species are Gram-negative, saprophytic, motile bacilli. Exposure to aquatic environment and raw fish ingestion have been defined as significant associated risk factors. The two species most commonly associated with human infections are Shewanella algae and Shewanella putrefaciens and major portion of infections (80%) caused by the former. Herein, we report a case of Shewanella septicaemia in a 70-year-old man in Omaha, NE who had no exposure to aquatic environment. To date, no defined treatment guidelines are present due to rarity of Shewanella infections, which is contributing to emerging antibiotic resistance.

Genomic investigation of emerging zoonotic pathogen Shewanella xiamenensis

Objective:

Shewanella xiamenensis is an emerging zoonotic pathogen commonly found in aquatic ecosystem. Clustered regularly interspaced short palindromic repeats (CRISPR) and (CRISPR)-associated gene systems act as adaptive immune system of prokaryotes. Recently, growing evidence suggested their role in bacterial virulence and resistance. Despite its medical importance, little is known about the genomic characteristics of S. xiamenensis.

Materials and Methods:

Strain ZYW6 was isolated from Epinephelus awoara. We sequenced the 16S rRNA gene and blast against the GenBank bacterial database. Antibiotic susceptibility tests and interpretation were performed by automatic VITEK 2 system. We extracted the genomic DNA with QIAGEN Genomic-tip 100/G kit and QIAGEN Genomic DNA Buffer Set. Whole-genome shotgun sequencing was performed using the Illumina MiSeq sequencer. To identify the CRISPR-Cas System in the genome of S. xiamenensis ZYW6, the Integrated Microbial Genomes and Microbiomes and CRISPRFinder were used.

Results:

We characterized the genome of a S. xiamenensis strain. The genome is 4,765,190 bp in length and encodes 4262 open-reading frames. Type I CRISPR-Cas system and serine biosynthesis genes were identified.

Conclusion:

Our results demonstrate the genetic structure of CRISPR-Cas system, l-serine synthesis, and oxacillinase in S. xiamenensis. The report of antibiotics resistance genes in the study might indicate a possible reservoir of antimicrobial drug resistance determinants in food animal, resulting in potential infection source. The findings provide insights into the structure and composition of CRISPR-Cas system in S. xiamenensis and foundation for future biological validation.

Genome Sequence of Colistin-Resistant Bacteremic Shewanella algae Carrying the Beta-Lactamase Gene bla OXA-55

Shewanella algae is an emerging pathogen widely distributed in aquatic environment. Bacteremia is a major manifestation of S. algae infections, and there are increasing reports of antibiotic-resistant strains. However, little is known about the genomic characteristics of human bacteremic S. algae. Here, we report the results of the whole-genome sequencing of colistin-resistant S. algae TYL, a blood isolate. Chromosome-encoded pmrC associated with colistin resistance and bla_OXA-55 gene intrinsic to S. algae was identified. Continuous surveillance for the emergence of S. algae is needed.

Definition of a Family of Nonmobile Colistin Resistance (NMCR-1) Determinants Suggests Aquatic Reservoirs for MCR-4

Polymyxins, a family of cationic antimicrobial peptides, are recognized as a last-resort clinical option used in the treatment of lethal infections with carbapenem-resistant pathogens. A growing body of mobile colistin resistance (MCR) determinants renders colistin ineffective in the clinical and human sectors, posing a challenge to human health and food security. However, the origin and reservoir of the MCR family enzymes is poorly understood. Herein, a new family of nonmobile colistin resistance (from nmcr-1 to nmcr-1.8) from the aquatic bacterium Shewanella is reported. NMCR-1 (541aa) displays 62.78% identity to MCR-4. Genetic and structural analyses reveal that NMCR-1 shares a similar catalytic mechanism and functional motifs, both of which are required for MCR action and its resultant phenotypic resistance to polymyxin. Phylogeny and domain-swapping demonstrate that NMCR-1 is a progenitor of MCR-4 rather than MCR-1/2. Additionally, the experiment of bacterial growth and viability reveals that NMCR-1 promotes fitness cost as MCR-1/4 does in the recipient Escherichia coli. In summary, the finding suggests that the aquatic bacterium Shewanella (and even its associated aquaculture) is a reservoir for MCR-4 mobile colistin resistance.

ICE SXT vs. ICESh95: Co-existence of Integrative and Conjugative Elements and Competition for a New Host

Integrative and conjugative elements (ICEs) are mobile genetic elements that contribute to horizontal gene transfer. The aim of this work was to study different types of ICEs in clinical isolates of the emergent pathogen Shewanella spp., to compare their transfer efficiency and their ability to integrate a new host. Here we show that 3 out of 10 clinical isolates contained an ICE. Two of these elements were similar to ICEs from the SXT/R391 family and the other one was similar to ICESh95, a hybrid platform. Mating assays showed that these elements co-exist for several generations in the same host. Furthermore, transfer rates and competition assays between ICESh95 and ICESh392, an SXT-like element, suggest that the latter has evolved into a well-oiled machine that efficiently spread to different bacteria. Our results provide strong evidence of the role that ICEs play in the dissemination of genetic traits in nature and the implications that they have in the global threat of antimicrobial resistance.