Skin and soft-tissue manifestations of Shewanella putrefaciens infection

Characterization of CRISPR-Cas Systems in Shewanella algae and Shewanella haliotis: Insights into the Adaptation and Survival of Marine Pathogens

CRISPR-Cas systems are adaptive immune mechanisms present in most prokaryotes that play an important role in the adaptation of bacteria and archaea to new environments. Shewanella algae is a marine zoonotic pathogen with worldwide distribution, which accounts for the majority of clinical cases of Shewanella infections. However, the characterization of Shewanella algae CRISPR-Cas systems has not been well investigated yet. Through whole genome sequence analysis, we characterized the CRISPR-Cas systems in S. algae. Our results indicate that CRISPR-Cas systems are prevalent in S. algae, with the majority of strains containing the Type I-F system. This study provides new insights into the diversity and function of CRISPR-Cas systems in S. algae and highlights their potential role in the adaptation and survival of these marine pathogens.

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.

Analysis of clinical characteristics of infections caused by Shewanella species

PURPOSE

The Shewanella genus is a rare pathogen of marine origin. In recent years, there has been a continuous increase in infection cases caused by this bacterium, and we have observed the uniqueness of infections caused by this microorganism.

MATERIALS AND METHODS

This study conducted a retrospective analysis of the medical history and laboratory examination data of patients infected with the Shewanella genus over the past decade. Additionally, it employed bioinformatics methods to analyze the relevant virulence factors and antibiotic resistance genes associated with the Shewanella genus.

RESULTS

Over the past 10 years, we have isolated 51 cases of Shewanella, with 68.82% being Shewanella putrefaciens (35/51 cases) and 31.37% being Shewanella algae (16/51 cases). Infected individuals often had underlying diseases, with 39.22% (20/51) having malignant tumors and 25.49% (13/51) having liver and biliary system diseases primarily characterized by stones. The majority of patients, 62.74% (32/51), exhibited mixed infections, including one case with a combination of infections from three other types of bacteria and five cases with a combination of infections from two other types of bacteria. The identified microorganisms were commonly resistant to ticarcillin-clavulanic acid (23.5%), followed by cefoperazone-sulbactam (19.6%), ciprofloxacin (17.6%), and cefotaxime (17.6%). Bioinformatics analysis indicates that Shewanella can express bile hydrolysis regulators and fatty acid metabolism regulators that aid in adapting to the unique environment of the biliary tract. Additionally, it expresses abundant catalase, superoxide dismutase, and two-component signal transduction system proteins, which may be related to environmental adaptation. Shewanella also expresses various antibiotic resistance genes, including beta-lactamases and aminoglycoside modification enzymes. Iron carriers may be one of its important virulence factors.

CONCLUSIONS

We speculate that the Shewanella genus may exist as a specific colonizer in the human body, and under certain conditions, it may act as a pathogen, leading to biliary infections in the host.

Genus Shewanella: A Potential Intestinal Colonizer Associated With Post-Operative Surgical Site Infections in Coastal Regions

Background: This study aims to elucidate the clinical characteristics of Shewanella-related surgical site infections (SSIs) and assess the risk of mortality in patients by establishing a predictive model. Patients and Methods: A retrospective analysis of medical history and laboratory data of Shewanella-related SSI patients over the past decade was conducted via the electronic medical record (EMR) system. A predictive model for mortality risk in Shewanella-related SSI patients was established using plasma interleukin-6 (IL-6) levels combined with the Howell-PIRO scoring system. Results: Over the past 10 years, 45 strains of Shewanella were isolated from specimens such as bile, drainage fluid, and whole blood in patients with digestive tract SSIs. Among them, 21 of 45 (46.67%) patients underwent malignant tumor resection of the digestive system, 14 of 45 (31.11%) underwent endoscopic retrograde cholangiopancreatography (ERCP) common bile duct exploration or the stone removal, and seven of 45 (15.56%) were trauma repair patients with fractures and abdominal injuries. Among the 45 Shewanella-related SSI patients, 10 died within 30 days of infection, six cases involved infections with more than two other types of bacteria. The combined use of IL-6 and Howell-PIRO scores for mortality risk assessment yielded an receiver operating characteristic (ROC) curve with an area under the curve (AUC) of 0.9350, a positive predictive value of 92.71%, a negative predictive value of 94.58%, a diagnostic sensitivity of 95.35%, and a diagnostic specificity of 92.14%-all higher than the model using IL-6 or Howell-PIRO scores alone. Conclusions: We found that residents in coastal areas faced an increased risk of Shewanella-related SSI. Moreover, the higher the number of concurrent microbial infections occurring alongside Shewanella-related SSI, the greater the mortality rate among patients. The combined application of plasma IL-6 levels and the Howell-PIRO scoring system is beneficial for assessing patient mortality risk and guiding timely and proactive clinical interventions.

Microbiological analysis of skin lesions of cod (Gadus morhua) from the southern part of the Baltic Sea

Introduction

Since the middle of the 1980s, severe skin disorders have been observed in Baltic cod (Gadus morhua) each year. Available data on the spectrum of bacteria isolated from the clinical cases being limited, and evaluation of the microbial background of fish skin lesions being useful, a bacteriological examination has been undertaken.

Material and Methods

A total of 1,381 cod were caught during two voyages of the Baltica research vessel in the Polish exclusive economic zone of the southern Baltic Sea. After an examination which found lesions in 164 of the fish, a microbiological analysis was performed to isolate bacteria from them. The collected strains were phenotyped and genotyped, and their antimicrobial resistance was analysed by minimum inhibitory concentration (MIC) techniques.

Results

Bacteriological examinations provided 850 isolates. The dominant microorganisms were mesophilic Aeromonas spp., Pseudomonas spp. and Shewanella baltica. Opportunistic bacteria potentially hazardous to human health were also isolated, e.g. Alcaligenes faecalis, Staphylococcus epidermidis, Stenotrophomonas maltophilia and Vibrio sp. The MIC analysis determined the highest number of bacteria to resist sulphamethoxazole and amoxicillin and clavulanic acid.

Conclusion

Most of the collected bacteria were opportunistic pathogens for fish, widespread in the aquatic environment, and potentially threatening to humans.

Shewanella putrefaciens, a rare human pathogen: A review from a clinical perspective

Shewanella putrefaciens is a gramnegative, facultatively anaerobic, rod shaped bacterium. It belongs to the class of the Gammaproteobacteria and was first described in 1931. S. putrefaciens is part of the marine microflora and especially present in moderate and warm climates. The bacterium is a rare oppurtonistic human pathogen associated mainly with intra-abdominal as well as skin and soft tissue infections. However, it has also been reported in association with more severe diseases such as pneumonia, intracerebral and ocular infections and endocarditis. In these cases the clinical courses are often associated with underlying, predisposing diseases and risk factors. For successful treatment of S. putrefaciens, a combination of appropriate local therapy, e.g. surgical treatment or drainage, and antibiotic therapy should be performed. Since multiple resistances to antibiotics are described, the results of the antimicrobial susceptibility testing must be considered for effective therapy as well. Furthermore, a main challenge in clinical practice is the accurate microbiological identification, and especially the correct differentiation between S. putrefaciens and S. algae. Under certain circumstances, Shewanella-infections can have severe, sometimes even fatal consequences. Therefore, we decided to present the current state of knowledge as well as further aspects with regard to future diagnostics, therapy and research.

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.

Emerging Infections Due to Shewanella spp.: A Case Series of 128 Cases Over 10 Years

Background

Shewanella species are emerging pathogens that can cause severe hepatobiliary, skin and soft tissue, gastrointestinal, respiratory infections, and bacteremia. Here we reported the largest case series of infections caused by Shewanella species.

Aim

To identify the clinical features and risk factors predisposing to Shewanella infections. To evaluate resistance pattern of Shewanella species and appropriateness of antibiotic use in the study cohort.

Methods

Patients admitted to a regional hospital in Hong Kong with Shewanella species infection from April 1, 2010 to December 31, 2020 were included. Demographics, antibiotics, microbiology, and outcomes were retrospectively analyzed.

Findings

Over the 10 years, we identified 128 patients with Shewanella species infection. 61.7% were male with a median age of 78 (IQR 65–87). Important underlying diseases included hepatobiliary diseases (63.3%), malignancy (26.6%), chronic kidney disease or end-stage renal failure (25.8%), and diabetes mellitus (22.7%). Hepatobiliary infections (60.4%) were the most common clinical manifestation. Majority (92.2%) were infected with Shewanella algae, while 7.8% were infected with Shewanella putrefaciens. The identified organisms were usually susceptible to ceftazidime (98.7%), gentamicin (97.4%), cefoperazone-sulbactam (93.5%) and ciprofloxacin (90.3%). Imipenem-susceptible strains were only present in 76.6% of isolates.

Conclusion

This largest case series suggested that Shewanella infections are commonly associated with underlying comorbidities, especially with hepatobiliary diseases and malignancy. Although Shewanella species remained largely susceptible to third and fourth generation cephalosporins and aminoglycosides, carbapenem resistance has been on a significant rise.

Infections following stingray attacks: A case series and literature review of antimicrobial resistance and treatment

BACKGROUND

Injuries sustained following stingray attacks are at high risk of infection and can progress to serious, debilitating consequences for the patient if not appropriately addressed. Antibiotic treatment of such infections is important to minimise the morbidity experienced by patients. However, antibiotic guidelines relating specific to this patient group are not well established. This study aims to report the experience of a single institution at treating stingray associated wound infections and to review the literature for reported cases. Additionally, we review the microbiological risk in these patients and summarise the literature surrounding antibiotic choice.

METHODS

A retrospective review of all patients presenting with injuries sustained following stingray attacks was conducted at a single institution. Additionally, a comprehensive literature review was conducted to identify cases of infected stingray associated trauma and review the causative micro-organisms and antibiotics used to treat such infections.

RESULTS

22 cases of stingray injuries were identified from a single institution. Of these, eight infections were reported. One case grew a highly resistant Vibrio species. Among the literature, 18 cases of infections were identified many of which led to significant complications for patients. The micro-organisms identified were diverse and there was little consistency among the antibiotic regimens utilised.

CONCLUSION

Based on the antibiotic susceptibilities of causative bacteria along with extrapolation from recommendations and guidelines identified in the literature, ciprofloxacin, doxycycline and trimethoprim-sulfamethoxazole appear to be the most appropriate antibiotics choices for prophylaxis or treatment of localised infection. Antibiotic choices for the empiric treatment of systemic infection requires further research and clarification.

Cellulitis: A Review of Current Practice Guidelines and Differentiation from Pseudocellulitis

Cellulitis, an infection involving the deep dermis and subcutaneous tissue, is the most common reason for skin-related hospitalization and is seen by clinicians across various disciplines in the inpatient, outpatient, and emergency room settings, but it can present as a diagnostic and therapeutic challenge. Cellulitis is a clinical diagnosis based on the history of present illness and physical examination and lacks a gold standard for diagnosis. Clinical presentation with acute onset of redness, warmth, swelling, and tenderness and pain is typical. However, cellulitis can be difficult to diagnose due to a number of infectious and non-infectious clinical mimickers such as venous stasis dermatitis, contact dermatitis, eczema, lymphedema, and erythema migrans. Microbiological diagnosis is often unobtainable due to poor sensitivity of culture specimens. The majority of non-purulent, uncomplicated cases of cellulitis are caused by β-hemolytic streptococci or methicillin-sensitive Staphylococcus aureus, and appropriate targeted coverage of this pathogen with oral antibiotics such as penicillin, amoxicillin, and cephalexin is sufficient. Even with rising rates of community-acquired methicillin-resistant Staphylococcus aureus, coverage for non-purulent cellulitis is generally not recommended.

Shewanella putrefaciens: A cause of bacteremia not to neglect

Shewanella putrefaciens is a Gram-negative bacillus and marine pathogen that rarely causes disease in humans. We report the first Moroccan case of multidrug-resistant Shewanella putrefaciens bacteremia and describe the bacteriological, clinical, and antibiogram characteristics of this isolate, which was repeatedly isolated from the blood of a 66-year-old hypertensive man who underwent femoral coronary angiography after a myocardial infarction.

Surfing Injuries: A Review for the Orthopaedic Surgeon

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Surfing is safe: the risk of injury ranges from 0.26 to 0.90 injuries per surfer per year, 0.06 to 3.5 injuries per 1,000 days of surfing, and 1.1 to 13.0 injuries per 1,000 hours of surfing.

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The most common acute surfing injuries are lacerations, contusions, and sprains; the head and the neck as well as the lower extremities are the locations that are affected most.

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The most common mechanism of injury is striking a surfer's own board or that of another surfer.

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A pathology that is unique to surfers is surfer's myelopathy; bites and/or stings by sea life and infections caused by marine life also occur in surfers.

Main bacterial species causing clinical disease in ornamental freshwater fish in Brazil

Bacterial diseases are common in ornamental fish, more frequently associated with ubiquitous bacteria from the aquarium environment. The disease can lead to fish mortality and cause high economic losses if not rapidly controlled. The aim of this study was to identify the main causative bacterial agents of infection in ornamental fish with different clinical signs. A total of 126 freshwater fish, from 12 families and 38 species, with clinical signs were collected in a wholesaler in São Paulo, SP, Brazil. Samples were taken from the eye, skin ulcers, kidneys, and gills, plated on MacConkey, CHROMagar Orientation, and blood agar and incubated under aerobic and anaerobic conditions. Bacterial identification was performed by MALDI-TOF mass spectrometry. From the 126 studied animals, 112 were positive for bacterial isolation. Among the positive animals, 32.1% presented infection caused by a single bacterial species, while in the remaining 67.9%, two to six different bacterial species were identified. A total of 259 bacterial strains were obtained and classified among 46 bacterial species. The species of higher frequency were Aeromonas veronii (26.3%), Aeromonas hydrophilla (16.2%), Shewanella putrefaciens (7.3%), Citrobacter freundii (8.1%), Vibrio albensis (5.8%), and Klebsiella pneumoniae (4.2%). MALDI-TOF MS showed to be a rapid method for diagnosis of bacterial disease outbreaks in ornamental fish establishments.

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.

Pyogenic Flexor Tenosynovitis Caused by Shewanella putrefaciens

Flexor tenosynovitis is a surgical emergency due to the risk of tendon necrosis which can lead to subsequent amputation. We report a case of flexor tenosynovitis with Shewanella putrefaciens as the implicated organism, though the patient’s mechanism of penetrating trauma did not involve a marine exposure. Shewanella are Gram negative bacilli associated with marine environments and have rarely been implicated in human disease. This patient presented with all four of Kanavel’s signs and required open surgical irrigation and debridement; he was found to have purulence but no flexor tendon necrosis. This case emphasizes the importance of considering marine organisms as putative for flexor tenosynovitis, even if marine exposure does not occur at the time of the penetrating trauma. It also emphasizes the need to obtain a thorough patient history, especially in cases of infection, to assess for all possible environmental exposures.

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.

Prevalence and antibiotic sensitivity of bacteria isolated from imported ornamental fish in Italy: A translocation of resistant strains?

The rapid expansion of the ornamental aquaculture industry over the past decades has resulted in a concomitant increase in the use of antibiotics to combat infectious diseases. The aim of this study was to assess the possible role of ornamental fish in the translocation of antibiotic resistant bacteria, with possible consequences for aquarium and public health. We assessed the prevalence of bacterial infections and the antibiotic resistance profile of bacteria isolated from 134 ornamental fish imported into northwest Italy during two years of monitoring. Ornamental fish analyzed were imported mainly from Singapore (40%) and Israel (20%), followed by Thailand (13%), Sri Lanka (12%), Czech Republic (7%), Vietnam (5%) and Indonesia (3%). The most commonly imported fish were freshwater species, particularly those belonging to the Poeciliidae family. Bacteriological exam was positive in 68% of the fish examined. The most frequently isolated bacterium was Aeromonas sobria (37%). Bacteria showed resistance against lincomycin, ampicillin, oxytetracycline and tetracycline. Sensitivity was found for florfenicol, chloramphenicol, gentamicin, and trimethoprim/sulfamethoxazole. Odds ratio (OR) values were calculated as a measure of the association between antibiotic resistance of A. sobria and selected factors (country of origin, fish family and fish species), considering Thailand, Poeciliidae and Poecilia reticulata as control cases. Higher values were found for Vietnam (OR 5.6) and Xiphophorus helleri and X. maculatus (OR 3.0 and 3.7 respectively). Our findings underline the need to improve targeted surveillance of antimicrobial resistance and prevent the translocation of resistant or multi-resistant bacterial strains in ornamental fish, especially in fish imported from countries where surveillance is limited or lacking.

Ulcerative dermatitis in barramundi due to coinfection with Streptococcus iniae and Shewanella algae

Streptococcus iniae is a pathogenic bacterium which causes septicaemia, while Shewanella algae is an opportunistic pathogen found in marine environments. In this study, we investigated an uncommon coinfection of these 2 bacterial species which resulted in systemic disease and cutaneous ulcers in a barramundi Lates calcarifer farm in the Persian Gulf, Iran. Culture, molecular and histopathological specimens were taken from different organs. In histopathology, results indicated deep bacterial ulceration of skin and subcutaneous muscles. Haemorrhage and hyperaemia were the most common signs observed in visceral organs. In culture, Gram-positive cocci were grown from visceral organs while Gram-negative bacilli were isolated from ulcers. In molecular examination, Streptococcus iniae and Shewanella algae were identified from visceral and ulcer samples, respectively, by PCR of the 16S rRNA gene. The disk diffusion method was used to determine antimicrobial susceptibility of isolated bacteria, with Shewanella algae being resistant to most routinely used antibiotics. In this study, a mixed infection of 2 bacterial species was found; we conclude that systemic streptococcosis could act as a predisposing factor for Shewanella penetration into skin and subsequent ulcer formation. Coinfections are very common in mammals; however, this subject has received little attention in other species, such as fish, and particularly in aquaculture. This study highlights the potential significance of coinfections in barramundi, the effect on the severity of the disease and the potential for new opportunistic pathogens arising.

Swimming with the Pigs: A Case of Severe Soft Tissue Infection during a Caribbean Vacation

A 74-year-old man presented to the emergency department with severe right leg cellulitis following a trip to the Bahamas where he swam in both chlorinated pools and the ocean. His blood cultures grew Shewanella species, a marine pathogen known to cause disease in humans, following exposure to seawater. He was treated with cefepime for a total of two weeks without needing any surgical intervention. The patient had complete resolution of infection and was able to return to his activities of daily living.

Rare Shewanella spp. associated with pulmonary and bloodstream infections of cancer patients, China: a case report

Background

Members of Shewanella species are opportunistic pathogens that are found in marine environments. Currently more than sixty species have been identified, whereas the most commonly clinical cases associated with Shewanella species have involved only two species, i.e., S. algae and S. putrefaciens. We present two cases of pulmonary and bloodstream infections caused by two rare Shewanella spp. strains from patients of gastrointestinal cancer.

Case presentation

Two male patients with a history of gastrointestinal cancer presented to hospital with pulmonary and bloodstream infections, respectively. The infective pathogens of both cases were primarily isolated and identified as Shewanella algae (case I) and Shewanella putrefaciens (case II) by phenotypic features and VITEK 2 system, but they were further confirmed as Shewanella haliotis and Shewanella upenei by 16S rRNA gene sequence analysis. The major bacterial composition of the bronchoalveolar lavage in case I was also identified as Shewanella by 16S rRNA amplicon sequencing analysis. Antimicrobial susceptibility testing showed that the two strains had broad susceptibility, but S. haliotis in the case I was resistant to ciprofloxacin and levofloxacin and S. upenei in the case II was intermediate to imipenem, piperacillin/tazobactam and ciprofloxacin.

Conclusions

To the best of our knowledge, this is the first cases of the pulmonary and bloodstream infections caused by Shewanella spp. from clinical patients in mainland China. Shewanella as a potential pathogen in China should not be ignored.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3354-8) contains supplementary material, which is available to authorized users.

Methods for identification and differentiation of different Shewanella spp. isolates for diagnostic use

Shewanella spp. are Gram-negative, rod-shaped, motile bacteria that are widely distributed in marine and freshwater environments. The bacteria are present in the physiological microflora of fish from temperate waters and are known as fish spoilage species. From clinically healthy fish and from fish with skin ulcerations, Shewanella spp. is regularly isolated, indicating a possible role as fish pathogen. In this study, 74 isolates of Shewanella spp. were analysed. For species identification, biochemical techniques, 16S rRNA sequencing, MALDI-TOF MS and the Sherlock Microbial Identification System (MIS) based on the composition of fatty acid ethyl esters were compared. The phylogenetic relationship, cytotoxicity in vitro and resistance against antibiotics were tested. The most reliable method for species identification was 16S rRNA sequencing. From diseased fish, clinically healthy fish and the aquatic environment, different Shewanella species were isolated. This indicates that Shewanella spp. is widespread in the aquatic milieu and acts as a secondary pathogen. The virulence of Shewanella spp. is probably not depending on the species but on the isolate itself. Many isolates of Shewanella spp. were showing multiresistances against antibiotic substances, especially in samples derived from retailers and in routine diagnostics, all Shewanella spp. should therefore be tested for resistances against antibiotic agents.

Shewanella algae infection in Italy: report of 3 years' evaluation along the coast of the northern Adriatic Sea

Shewanella algae are Gram-negative, nonfermentative, motile bacilli, classified in the genus Shewanella in 1985. These environmental bacteria are occasionally identified in human infections, with a relatively strong association with exposure to seawater during warm seasons. This report describes a case series of 17 patients with infection correlated to S. algae in the coastal area of Romagna, Italy, from 2013 to 2016. The types of infection included otitis, pneumonia, sepsis and soft tissue (wound). Exposure to the marine environment during hot months was confirmed in 12 of 17 patients. An apparent correlation between increased severity of infection and patient age was also observed.

Palmar Soft Tissue Infection From Shewanella putrefaciens

Shewanella putrefaciens, a gram-negative bacillus, ubiquitous in marine environments, is an opportunistic agent reported to cause rare human infection, most commonly in patients who are immunocompromised or who have a preexisting soft tissue defect. We present an immunocompetent, 40-year-old woman with a soft tissue infection of the left palm caused by S. putrefaciens. The patient's infection was complicated by the presence of retained foreign bodies, seashell fragments, from a traumatic fall. Following appropriate evaluation and surgical treatment, our patient experienced a successful outcome with no recurrence of infection or deficit in the affected hand. This case report complements the growing literature regarding morbidity attributed to S. putrefaciens infection.

CTX-M-15-Producing Shewanella Species Clinical Isolate Expressing OXA-535, a Chromosome-Encoded OXA-48 Variant, Putative Progenitor of the Plasmid-Encoded OXA-436

Shewanella spp. constitute a reservoir of antibiotic resistance determinants. In a bile sample, we identified three extended-spectrum-β-lactamase (ESBL)-producing bacteria (Escherichia coli, Klebsiella pneumoniae, and Shewanella sp. strain JAB-1) isolated from a child suffering from cholangitis. Our objectives were to characterize the genome and the resistome of the first ESBL-producing isolate of the genus Shewanella and determine whether plasmidic exchange occurred between the three bacterial species. Bacterial isolates were characterized using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), standard biochemical tools, and antimicrobial susceptibility testing. Shewanella sp. JAB-1 and ESBL gene-encoding plasmids were characterized using PacBio and Illumina whole-genome sequencing, respectively. The Shewanella sp. JAB-1 chromosome-encoded OXA-48 variant was cloned and functionally characterized. Whole-genome sequencing (WGS) of the Shewanella sp. clinical isolate JAB-1 revealed the presence of a 193-kb plasmid belonging to the IncA/C incompatibility group and harboring two ESBL genes, bla_CTX-M-15 and bla_SHV-2abla_CTX-M-15 gene-carrying plasmids belonging to the IncY and IncR incompatibility groups were also found in the E. coli and K. pneumoniae isolates from the same patient, respectively. A comparison of the bla_CTX-M-15 genetic environment indicated the independent origin of these plasmids and dismissed in vivo transfers. Furthermore, characterization of the resistome of Shewanella sp. JAB-1 revealed the presence of a chromosome-carried bla_OXA-535 gene, likely the progenitor of the plasmid-carried bla_OXA-436 gene, a novel bla_OXA-48-like gene. The expression of bla_OXA-535 in E. coli showed the carbapenem-hydrolyzing activity of OXA-535. The production of OXA-535 in Shewanella sp. JAB-1 could be evidenced using molecular and immunoenzymatic tests, but not with biochemical tests that monitor carbapenem hydrolysis. In this study, we have identified a CTX-M-15-producing Shewanella species that was responsible for a hepatobiliary infection and that is likely the progenitor of OXA-436, a novel plasmid-encoded OXA-48-like class D carbapenemase.

Isolation of Shewanella putrefaciens in an elderly man with subacute intestinal obstruction & appendicitis

Shewanella is Gram-negative motile bacillus, non fermentative and facultative anaerobe. Its natural habitat is all forms of water and soil, but has also been isolated from fish, dairy products, oils, and carcasses. Often found with microflora of the marine environment. Bacterial infections with Shewanella spp. are rare. The exposure to the marine environment, sea and diary food are considered as a risk factor for Shewanella spp. infection. Clinical infections seen are otitis, soft tissue infection, bacteremia, ear infection, eye infection, infective arthritis, osteomyelitis, infective endocarditis and peritonitis.

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

Shewanella spp. are commonly known as environmental bacteria and are most frequently isolated from aquatic areas. Currently, diseases syndromes and multidrug resistance have increasingly been reported in the genus Shewanella. Some species are associated with various infections, such as skin and soft tissue infections, as well as bacteremia. Generally, these bacteria are opportunistic and mostly affect people with an impaired immune system. This genus is also a probable vehicle and progenitor of antibiotic resistance genes. In fact, several resistance genes and mobile genetic elements have been identified in some resistant species isolated from environmental or clinical settings. These genes confer resistance to different antibiotic classes, including those used in therapies such as β-lactams and quinolones, and are generally located on the chromosome. Recently, a multidrug-resistant (MDR) plasmid harboring several drug resistance genes associated with transposons and integrons has been identified in Shewanella xiamenensis. These antibiotic resistance genes can circulate in the environment and contribute to the emergence of antibiotic resistance. This review describes different aspects of Shewanella, focusing on the infections caused by this genus, as well as their role in the propagation of antibiotic resistance via mobile genetic elements.

Antibiotic and heavy metal resistance in Shewanella putrefaciens strains isolated from shellfishes collected from West Sea, Korea

The aim of the present study was to determine the antibiotic resistance patterns and distribution of heavy-metal resistance in Shewanella putrefaciens strains isolated from shellfishes collected from West Sea; and to determine the relationship, if any, between antibiotic and heavy-metal resistance in these strains. Among the 15 strains isolated, two strains, SY1 and SY2, showed heavy-metal resistance in addition to high resistance to seven antibiotics: cephalothin, gentamicin, erythromycin, vancomycin, ampicillin, rifampicin, and streptomycin. We conclude that heavy-metal contamination imposes long-term, widespread, and recalcitrant selection pressure, which potentially contributes to the maintenance and spread of antibiotic resistance factors in bacteria. Moreover, this fact holds both environmental and clinical importance.

Skin, soft tissue and systemic bacterial infections following aquatic injuries and exposures

: Bacterial infections following aquatic injuries occur commonly in fishermen and vacationers after freshwater and saltwater exposures. Internet search engines were queried with the key words to describe the epidemiology, clinical manifestations, diagnostic and treatment strategies and outcomes of both the superficial and the deeper invasive infections caused by more common, newly emerging and unusual aquatic bacterial pathogens. Main findings included the following: (1) aquatic injuries often result in gram-negative polymicrobial infections with marine bacteria; (2) most marine bacteria are resistant to 1st- and 2nd-generation penicillins and cephalosporins; (3) nontuberculous, mycobacterial infections should be considered in late-onset, culture-negative and antibiotic-resistant marine infections; (4) superficial marine infections and pre-existing wounds exposed to seawater may result in deeply invasive infections and sepsis in immunocompromised patients. With the exception of minor marine wounds demonstrating localized cellulitis, most other marine infections and all gram-negative and mycobacterial marine infections will require therapy with antibiotic combinations.

Phenotypical and genotypical characterization of Shewanella putrefaciens strains isolated from diseased freshwater fish

Between 2007 and 2012, a variety of disease outbreaks most often characterized by skin disorders were observed among different species of freshwater fish in Poland. In most cases, the clinical signs included focally necrotized gills, necrotic skin lesions or ulcers. Internally, haemorrhages, oedematous kidney and abnormal spleen enlargement were generally noted. The disorders were accompanied by increased mortality. Most of the problems concerned cultured common carp Cyprinus carpio L. and rainbow trout Oncorhynchus mykiss (Walbaum). Fish have been examined from a number of these farms, and additionally, the wild and ornamental fish with similar clinical signs of diseases were also tested. Bacteria were isolated consistently from lesions and internal organs. They had characteristic orange-pigmented colonies which grew in pure culture or constituted 55-95% of total bacterial flora. One hundred and eighteen isolates were collected and biochemically identified as Shewanella putrefaciens group, and this was confirmed by sequencing. Challenge tests confirmed the pathogenicity of these bacteria. This is the first report characterizing and describing S. putrefaciens as a pathogen of different species of freshwater fish in Europe.

Neonatal sepsis caused by Shewanella algae: A case report

Sepsis remains a leading cause of mortality among neonates, especially in developing countries. Most cases of neonatal sepsis are attributed to Escherichia coli and other members of the Enterobacteriaceae family. Shewanella algae (S. algae) is a gram-negative saprophytic bacillus, commonly associated with the marine environment, which has been isolated from humans. Early onset neonatal sepsis caused by S. algae is uncommon. We report a case of S. algae blood stream infection in a newborn with early onset neonatal sepsis.

Quantitative and qualitative analyses of the bacterial microbiota of tilapia (Oreochromis niloticus) cultured in earthen ponds in the Philippines

The quantity and composition of the bacterial microbiota in the rearing water, sediment, gills and intestines of tilapia Oreochromis niloticus collected every 2 weeks from Day 30 to Day 120 after stocking for grow-out culture in 6 earthen brackish water ponds in the Philippines were examined. The total heterotrophic aerobic bacterial counts obtained in the water, sediment, gills and intestines of tilapia ranged from 10(3) to 10(4) c.f.u. ml(-1), 10(3)-10(5), 10(5)-10(7) and 10(4)-10(7) c.f.u. g(-1), respectively. In terms of composition, a total of 20 bacterial genera and 31 species were identified with the preponderance of gram-negative bacteria constituting 84 % of all bacterial isolates examined. Aeromonas hydrophila, Bacillus spp., Plesiomonas shigelloides, Shewanella putrefaciens, Pseudomonas fluorescens, Staphylococcus spp. and Vibrio cholerae were the dominant bacteria identified in the gills and intestine of tilapia. These bacteria also dominated in the pond sediment and rearing water, except for the nil isolation of S. putrefaciens and V. cholerae in the water samples examined, indicating that resident bacteria in the pond water and sediment congruently typify the composition of bacterial microbiota in the gills and intestine of tilapia which under stressful conditions may propel the ascendance of disease epizootics.

A Case of Spontaneous Bacterial Peritonitis with Bacteremia Caused by Shewanella algae

Human infection caused by Shewanella algae is rare, which usually occurred after direct contact with seawater or ingestion of raw seafood in the immunocompromised host. There have been anecdotal reports about Shewanella infections in human, but their pathogenic role and microbiologic data are limited. Here, we report a fatal case of spontaneous bacterial peritonitis with bacteremia due to S. algae in a 57-year-old male with liver cirrhosis who had no history of exposure to seawater or raw seafood. Polymicrobial infection with Streptococcus mitis and Escherichia coli was combined and the patient died in spite of early appropriate antimicrobial therapy and early goal-directed therapy for sepsis.

A case of wound infection caused by Shewanella algae in the south of Iran

Shewanella algae was isolated from the purulent discharge in the navel area of a young male with a history of swimming in the Persian Gulf. A routine laboratory diagnosis procedure, followed by 16S rRNA gene sequence analyses, was used to avoid misidentification with other species of Shewanella. The bacterium was suscetible to ceftazidime, ciprofloxacin, nalidixic acid, nitrophorantion, amikacin, ceftriaxone, cefotaxime, gentamicin and co-trimoxazole but was resistant to amoxicillin, vancomycin, doxycycline, cephalexin, ampicillin, tetracycline, cephalothin and ceftizoxime. The patient successfully recovered after treatment with antibiotics.

Systematic analysis of the association between gut flora and obesity through high-throughput sequencing and bioinformatics approaches

Eighty-one stool samples from Taiwanese were collected for analysis of the association between the gut flora and obesity. The supervised analysis showed that the most, abundant genera of bacteria in normal samples (from people with a body mass index (BMI) ≤ 24) were Bacteroides (27.7%), Prevotella (19.4%), Escherichia (12%), Phascolarctobacterium (3.9%), and Eubacterium (3.5%). The most abundant genera of bacteria in case samples (with a BMI ≥ 27) were Bacteroides (29%), Prevotella (21%), Escherichia (7.4%), Megamonas (5.1%), and Phascolarctobacterium (3.8%). A principal coordinate analysis (PCoA) demonstrated that normal samples were clustered more compactly than case samples. An unsupervised analysis demonstrated that bacterial communities in the gut were clustered into two main groups: N-like and OB-like groups. Remarkably, most normal samples (78%) were clustered in the N-like group, and most case samples (81%) were clustered in the OB-like group (Fisher's P  value = 1.61E − 07). The results showed that bacterial communities in the gut were highly associated with obesity. This is the first study in Taiwan to investigate the association between human gut flora and obesity, and the results provide new insights into the correlation of bacteria with the rising trend in obesity.

Shewanella algae: a rare cause of necrotizing fasciitis

BACKGROUND

The genus Shewanella consists of motile, gram-negative, facultative anaerobes found in marine environments. Shewanella putrefaciens and Shewanella algae are the two species with documented pathogenicity in human beings. Most documented cases of S. algae infection worldwide have been reported in the context of bacteremia, cellulitis, and acute exacerbations of chronic otitis media in predisposed individuals. We report a rare case of necrotizing soft tissue infection by S. algae in an immunocompetent individual. The infection followed exposure to S. algae in contaminated water in New York City, New York.

METHODS

We reviewed the English-language literature on similar cases of soft tissue infection using PubMed. Search terms included "Shewanella algae" and "Shewanella putrefaciens" in conjunction with "necrotizing" and "infection." Cognizant that this search method may not have yielded early (pre-1985) reports about Shewanella because of changes in classification and nomenclature, we also searched for "Pseudomonas putrefaciens."

RESULTS

After prompt surgical debridement and culture-directed antibiotic therapy, the patient recovered from his infection without the need for re-intervention.

CONCLUSIONS

This case may reflect the geographic spread and emergence of S. algae infection in the United States. Clinicians should be aware of the virulence of S. algae and potential for the rapid clinical deterioration of persons it infects even among immunocompetent individuals.

Shewanella putrefaciens, a rare cause of osteomyelitis

Shewanella putrefaciens is a Gram-negative bacillus with a distinguishable characteristic of hydrogen sulfide production and routinely found in a marine environment. This organism has been cultured as a pathogen in a small number of soft tissue infections, but has rarely been the causative agent in osteomyelitis. This case report details calcaneal osteomyelitis due to S putrefaciens in a 77-year-old male with bilateral heel ulcerations and peripheral vascular disease.

Identification of tetrodotoxin-producing Shewanella spp. from feces of food poisoning patients and food samples

Shewanella spp. is infrequently recovered from clinical specimens. Following two outbreaks of food poisoning, eight Shewanella spp. strains were obtained from the fecal specimens of patients, food and food processing-related materials. Tetrodotoxin (TTX) was identified in the culture supernatants of these strains, and the toxin's biological activity was detected using a mouse bioassay. This study suggested that Shewanella strains can colonize and survive in human intestines. The study also raises the issues of the accumulation of TTX produced by Shewanella in food and the possible role of TTX-producing Shewanella in food poisoning.

Human infection with Shewanella putrefaciens and S. algae: report of 16 cases in Martinique and review of the literature

Shewanella spp. are saprophytic bacteria that are part of the marine microflora in warm climates and are rarely pathogenic. However, Shewanella spp. infections are being increasingly reported, and there has been no comprehensive review of the literature describing these infections. This article reports 16 cases of Shewanella spp. infections in Martinique since 1997 and reviews another 239 cases reported in the literature since 1973. Patients experienced soft tissue infections, ear infection, or abdominal and biliary tract infections. A skin or mucosal portal of entry was found for 53% of the patients and exposure to the marine environment was reported for 44%; 79% of patients had an underlying condition. Bacteriema were frequent (28%). Most (87%) patients recovered, although ear infections can become chronic. Death occurred in 13% of the patients. Most Shewanella spp. isolates are susceptible to cefotaxime (95%), piperacillin and tazobactam (98%), gentamicin (99%), and ciprofloxacin (94%).

Clinical and microbiological features of shewanella bacteremia in patients with hepatobiliary disease

OBJECTIVE

Shewanella bacteremia is an uncommon but potentially fatal disease. Although hepatobiliary diseases have been proposed to be risk factors for various Shewanella infections, little is known about the features of Shewanella bacteremia in patients with hepatobiliary diseases. This study aims to characterize the presentation and risk factors of Shewanella bacteremia in patients with hepatobiliary diseases.

METHODS

We retrospectively investigated the clinical features, microbiology and outcomes of patients with Shewanella bacteremia who were admitted to a tertiary medical center between January 2001 and December 2010. All isolates were confirmed to the species level using 16S rRNA sequencing analyses. The English language medical literature was searched for previously published reports.

RESULTS

Fifty-nine cases of Shewanella bacteremia, including nine at the hospital, were identified, 28 (47.4%) of which involved underlying hepatobiliary diseases, representing an important risk factor. In 12 of the 28 cases, the infections involved the hepatobiliary system; with a tendency towards an Asian origin. In our case series of nine patients, Shewanella haliotis was isolated in five patients. The majority of our patients lived in coastal areas, consumed seafood regularly and developed bacteremia during the summer season.

CONCLUSION

It is recommended that the possibility for Shewanella infection be considered in patients with bacteremia and also underlying hepatobiliary diseases, particularly if patients present with hepatobiliary infections, a history of seafood, or development of the disease during the summer.