Primary Shewanella algae bacteremia mimicking Vibrio septicemia

A Rare Cause of Empyema and Bacteremia Due to Shewanella Species in Alcoholic Cirrhosis Patients: A Case Report and Comprehensive Review of Literature

BACKGROUND Shewanella spp. are gram-negative facultative anaerobic, oxidase-positive, motile bacilli that are ubiquitous but commonly occur in seawater and can cause opportunistic infection. Reports on the risk factors for Shewanella infection, its severity, antibiotic susceptibility, and prognosis are limited. This report is of a 78-year-old man with alcoholic cirrhosis presenting with bacteremia and empyema due to infection with Shewanella spp. CASE REPORT A 78-year-old man with alcoholic cirrhosis (Child-Pugh B) presented to our emergency room with a high fever. He had eaten raw fish one week prior to admission. Chest computed tomography showed a right unilateral pleural effusion, and he was hospitalized with suspected empyema. Shewanella spp. was detected in the pleural effusion and blood cultures. We initiated piperacillin/tazobactam and vancomycin empirically and switched to ceftriaxone; the effusion was successfully treated using antibiotics and pleural drainage. However, on hospitalization day 53, the patient died of aspiration pneumonia. In our literature review, we extracted 125 reported cases (including our case) and found that men were disproportionately affected (81%); median age was 61.6 (56-75) years; underlying diseases included hepatobiliary disease (33%), malignancy (25%), and cardiac disease (24%); Shewanella spp. infection sites were skin and soft tissue (35%), respiratory system (18%), and hepatobiliary system (11%); and management included antibiotics (100%), drainage (16%), and debridement (16%). The survival rate was 74% with antibiotics alone. CONCLUSIONS Our case highlights that clinicians should recognize Shewanella spp. as a cause of empyema and bacteremia in patients with liver cirrhosis, and that microbiological diagnosis with antibiotic sensitivity testing and treatment should be undertaken urgently to prevent fatal sepsis.

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.

A case of bacterial keratitis caused by multi-drug-resistant Shewanella algae without marine exposure

Shewanella are Gram-negative rods and marine pathogens. Here, we report a case of bacterial keratitis caused by Shewanella algae without marine exposure. A 66-year-old man with suspected pneumonia was sent to the emergency department from a nursing hospital. He had been in there for 2 years in a vegetative state and could not close his eyes voluntarily. Neither the patient nor his family had experienced any marine exposure. Keratitis was suspected in his right eye. Gram-negative rods grew from swab culture and identified as S. algae by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and 16S rRNA sequencing. The patient was treated with topical tobramycin, moxifloxacin and ofloxacin as well as steroids for 14 days, and the keratitis improved. S. algae is a rare human pathogen, and most human infections involve marine exposure. This is the second report of bacterial keratitis caused by S. algae worldwide and the first in Asia.

Assessment of seawater bacterial infection in rabbit tibia by Illumina MiSeq sequencing and bacterial culture

Objectives

We aimed to explore the bacterial community composition following ocean bacterial infection using an animal model.

Methods

This animal-based experiment was conducted from September 2019 to November 2019. Eighteen seawater filter membranes were collected from Changle City, Fujiian Province, China, on September 8, 2019. Ten filter membranes were used for implantation. Eight filter membranes that were used in the bacterial culture for the exploration of seawater bacteria were assigned to the seawater group (SG). Fourteen healthy adult New Zealand rabbits were randomly divided into the experimental group (EG) and control group (CG). Seawater filter membranes and asepsis membranes were implanted into the tibia in the EG and CG, respectively. One week after surgery, tibial bone pathology tissues were collected and assessed using light microscopy and scanning electron microscopy (SEM). Medullary cavity tissues were collected for the performance of Illumina MiSeq sequencing and bacterial culture. The differences between EG and CG were assessed by pathological observation under light microscopy and SEM, high-throughput bacterial sequencing, and bacterial culture.

Results

Compared with the CG, the infection rate was 100%, and the mortality value was 20% after the implantation of the filter membranes in the EG. Both light microscopy and SEM showed that a large number of bacteria were distributed in the bone marrow cavity after ocean bacterial infection. No bacterial growth was found in the CG. Illumina MiSeq sequencing found that Firmicutes, Proteobacteria, Thermotogae, Fusobacteria, Bacteroidetes, and Actinobacteria were the dominant bacteria at the phylum level and Clostridium_sensu_stricto_7, Haloimpatiens, Clostridium_sensu_stricto_15, Clostridiaceae_1, Clostridium_sensu_stricto_18, and Oceanotoga were the dominant bacteria in genus level among the EG. In the bacterial culture of the medullary cavity tissues, Klebsiella pneumoniae, Shewanella algae, Staphylococcus aureus, Escherichia coli, Enterobacter cloacae, and Vibrio vulnificus were the predominant infective species. Moreover, compared with the SG, the EG showed a higher detection rate of E. coli and S. aureus (P = 0.008 and P = 0.001, respectively). The detection rates of V. alginolyticus, V. parahaemolyticus, and V. fluvialis were higher in the SG than the EG (P = 0.007, P = 0.03, and P = 0.03, respectively).

Conclusions

Our model, which was comprehensively evaluated using four techniques: histopathology and SEM observation, gene detection, and bacteria culture, provides a scientific basis for the clinical diagnosis and treatment of patients in such settings.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-021-02553-9.

Characterization of putative pathogenic Shewanella algae isolated from ballast water

BACKGROUND AND AIM

Shewanella algae is ubiquitous in marine-associated environments and has been increasingly recognized as a significant human pathogen that can cause serious infections mainly associated with exposure to seawater and ingestion of raw seafood. This study aimed to isolate and characterize S. algae from ballast water of ships berthed at Port Klang, Malaysia.

MATERIALS AND METHODS

Ballast water was sampled from nine ships docked at Port Klang, Malaysia. The isolates were identified and characterized based on biochemical and enzymatic properties, 16S rRNA and gyrB sequencing, biofilm formation capability, and antibiotic susceptibility.

RESULTS

A total of four S. algae isolates were isolated from four ballast water samples tentatively name Sa-BW1, Sa-BW2, Sa-BW7, and Sa-BW8. All isolates showed positive reaction for cytochrome oxidase, catalase, high tolerance to NaCl (6% and 8%), ability to grow at 42°C, and on Salmonella-Shigella agar. The strains also exhibited b-hemolytic activity on sheep blood and human blood agar, positive reaction for lipase, protease, DNase and gelatinase, strong biofilm adherence capabilities and multiple antibiotic resistances against ampicillin, carbenicillin, cephalothin, colistin, novobiocin, oxacillin, penicillin, rifampicin, and tobramycin which suggested their potential pathogenicity.

CONCLUSION

This study demonstrated the occurrence of putative pathogen S. algae in ballast water of ships docked at Malaysian port.

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.

First case of Shewanella indica isolated from a Bryde's whale (Balaenoptera edeni) stranded in the northern Beibu Gulf, China

The purpose of this study was to culture and characterise bacteria from an intact abscess on the skin of a dead Bryde's whale (Balaenoptera edeni) which stranded in the northern Beibu Gulf, China. To grow bacteria, samples from the abscess were added to blood agar. After incubation, yellowish mucous colonies were visualized. The bacterium was firstly recognised as Shewanella algae by the VITEK® 2 System. However, by using 16S rRNA gene sequencing the bacterium was finally identified as S. indica. To characterise the bacterium, antibiotic susceptibility and virulence factors, such as hemolysis and biofilm formation were investigated. The bacterium is capable of β-hemolysis and biofilm formation and it is also sensitive to several different classes of antibiotics, such as β-lactams, quinolones, and aminoglycosides. To date there have been no reports of this bacterium causing infections in humans or animals. However, in this study we described the first case of S. indica isolated from an intact abscess on the back of a Bryde's whale.

The Pathogenicity of Shewanella algae and Ability to Tolerate a Wide Range of Temperatures and Salinities

Shewanella algae is a rod-shaped Gram-negative marine bacterium frequently found in nonhuman sources such as aquatic ecosystems and has been shown to be the pathogenic agent in various clinical cases due to the ingestion of raw seafood. The results of this study showed that S. algae was present in approximately one in four samples, including water and shellfish samples. Positive reactions (API systems) in S. algae strains were seen for gelatinase (gelatin); however, negative reactions were found for indole production (tryptophan). S. algae is adapted to a wide range of temperatures (4°C, 25°C, 37°C, and 42°C) and salinity. Temperature is a key parameter in the pathogenicity of S. algae as it appears to induce hemolysis at 25°C and 37°C. S. algae exhibits pathogenic characteristics at widely varying temperatures, which suggests that it may have the ability to adapt to climate change.

Shewanella spp. infections in Gran Canaria, Spain: retrospective analysis of 31 cases and a literature review

INTRODUCTION

Shewanella spp. can cause severe skin and soft-tissue infections, gastrointestinal infections, otitis and bacteraemia, generally upon contact with seawater or consumption of raw seafood. Recently, a new condition termed 'patera foot' characterized by acute skin and soft-tissue infection has been described in irregular immigrants arriving to the Canary Islands, Spain, in rudimentary boats. Most infections are caused by a single species, Shewanella algae. The improvement of the diagnostic capabilities in clinical microbiology laboratories has resulted in a growing number of cases being reported worldwide, most of them coming from warm regions.

CASE PRESENTATION

In this work, we reviewed the medical records of all the patients with Shewanella infections in the two university hospitals of Gran Canaria (the Canary Islands, Spain) during the period 2000-2016, resulting in the identification of 31 cases. We also conducted a literature review of Shewanella infections reported worldwide in recent years.

CONCLUSION

This case series suggests that Shewanella infections are nosocomially acquired more frequently than previously thought. In addition, the unexpectedly high proportion of multidrug-resistant isolates raises concerns.

Genome Sequences of Two Shewanella spp. Isolated from the Gut of the Sea Cucumber Apostichopus japonicus (Selenka, 1867)

In this study, we sequenced the genomes of two Shewanella spp., newly isolated from the gut of the sea cucumber Apostichopus japonicus (Selenka, 1867). The whole-genome sequences reported here will expand the repertoire of genomic information for the members of the genus Shewanella and will provide important insights into their roles within microbial communities.

The Phantom Menace for Patients with Hepatobiliary Diseases: Shewanella haliotis, Often Misidentified as Shewanella algae in Biochemical Tests and MALDI-TOF Analysis

Although Shewanella algae has been known to have weak pathogenicity, case reports on infections with this species have been steadily increasing. S. algae and S. haliotis are difficult to distinguish from each other with conventional phenotypic methods. We reviewed the microbiological and clinical features of S. algae and S. haliotis infections at our institute. Bacterial culture and identification reports from patient samples from 2010 to 2014 were reviewed to screen the cases of Shewanella infections. In addition to conventional biochemical tests, 16S rRNA gene sequence analysis and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry were performed for 19 stored bacterial isolates. Medical records were reviewed for clinical characteristics and laboratory findings. All isolates were identified as S. algae by using VITEK 2. MALDI-TOF also identified all isolates as S. algae with a 99.9 confidence value. In contrast, 16S rRNA analysis identified 10 isolates as S. algae and 9 isolates as S. haliotis. Both S. algae (60%) and S. haliotis (77%) infections were strongly associated with diseases of the hepatobiliary tract and pancreas. To distinguish between S. algae and S. haliotis, 16S rRNA gene sequence analysis seems more accurate than biochemical tests or MALDI-TOF. Patients with underlying diseases in the hepatobiliary tract and pancreas seem to be susceptible to these marine pathogens.

Shewanella-Related Bacteremia and Fournier's Gangrene: A Case Report

Shewanella algae and Shewanella putrefaciens have been implicated for causing serious infections in humans, including disseminated infection. We report the possible first case of Shewanella-related Fournier's gangrene and bacteremia caused in a 65-year-old Chinese male with nephrotic syndrome. He was successfully managed by surgical debridement and antibiotic therapy.

Shewanella algae in acute gastroenteritis

Shewanella algae is an emerging bacteria rarely implicated as a human pathogen. Previously reported cases of S. algae have mainly been associated with direct contact with seawater. Here we report the isolation of S. algae as the sole etiological agent from a patient suffering from acute gastroenteritis with bloody diarrhoea. The bacterium was identified by automated identification system and 16S rRNA gene sequence analysis. Our report highlights the importance of looking for the relatively rare aetiological agents in clinical samples that does not yield common pathogens. It also underscores the usefulness of automated systems in identification of rare pathogens.

Bacterial Landscape of Bloodstream Infections in Neutropenic Patients via High Throughput Sequencing

Background

Bloodstream infection (BSI) is a common and potentially life-threatening complication in patients with hematological malignancies and therapy-induced neutropenia. Administration of broad spectrum antibiotics has substantially decreased the mortality rate in febrile neutropenia, but bacterial infection is documented in only one-third or fewer of the cases. BSI is typically diagnosed by blood culture; however, this method can detect only culturable pathogens.

Methods

In the present study, a total of 130 blood samples from hematological patients receiving dose-intensive antitumoural treatment were subjected to 16S rRNA PCR and 62 of them were cultured. PCR positive samples were processed to high throughput sequencing by amplifying the V1-V3 regions of the 16S rRNA gene to obtain a full spectrum of bacteria present in BSI.

Results

Five phyla and 30 genera were identified with sequencing compared to 2 phyla and 4 genera with culture. The largest proportion of bacteria detected by sequencing belonged to Proteobacteria (55.2%), Firmicutes (33.4%) and Actinobacteria (8.6%), while Fusobacteria (0.4%) and Bacteroidetes (0.1%) were also detected. Ninety-eight percent of the bacteria identified by sequencing were opportunistic human pathogens and 65% belonged to the normal human microbiota.

Conclusions

The present study indicates that BSIs in neutropenic hosts contain a much broader diversity of bacteria, likely with host origin, than previously realized. The elevated ratio of Proteobacteria in BSI corroborates the results found in other systemic inflammatory diseases, such as inflammatory bowel disease or mucosal infections. This knowledge may become of value for tailoring antimicrobial drug administration.

Vibriosis

Vibriosis is a group of intestinal and extraintestinal infections caused by marine-dwelling bacteria of the genus Vibrio. Infections range from indolent illnesses to fulminant diseases, including cholera and necrotizing fasciitis. Most illnesses result from direct contact with the marine environment or consumption of shellfish, especially oysters. In the United States vibrio infections are increasing but are underreported because of lack of clinical recognition and appropriate detection in the microbiology laboratory. Recent advances to aid in the detection and identification of vibrio illnesses in the laboratory include rapid identification tests, new media, and molecular identification systems.

Skin and Soft Tissue Infections due to Shewanella algae - An Emerging Pathogen

INTRODUCTION

Shewanella spp. are emerging human pathogens, the predominant species being Shewanella algae. Shewanella skin and soft tissue infections are more commonly seen in immunocompromised patients with a pre-existing cutaneous ulcer and most often associated with exposure to marine environments.

AIM

The study was conducted to investigate the epidemiological and clinical characteristics of Shewanella skin and soft tissue infections (SSTIs) for a period of five years.

MATERIALS AND METHODS

All Gram-negative non-fermenting motile isolates which produced pigmented colonies and positive for oxidase and H2S were further identified with Vitek 2 system.

RESULTS

A total of 16 patients with SSTIs due to Shewanella species were identified during the period from 2010 to 2014. Majority of patients were urban, elderly and fisher men. Shewanella algae (n=12, 75%) was the predominant isolate. Skin or mucosal portal of entry was found in all patients and seawater contact was recorded in 56.25% of the patients. 81% of infections were polymicrobial, common concomitant pathogens being gut and marine flora. Peripheral vascular diseases were the predominant risk factors with comorbidities like diabetes, hypertension and hepatobiliary diseases. Third generation cephalosporins, meropenem and gentamicin were the most effective antibiotics while two of the isolates were multidrug resistant. 75% of the infected patients recovered completely and three patients died of complications.

CONCLUSION

Shewanella algae should be considered as an emerging pathogen of SSTIs mainly in patients with chronic ulcers and at times be multidrug resistant. These infections have a good clinical outcome if prompt medical, surgical and supportive treatment is offered.

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.

Bacteremia and empyema caused by Shewanella algae in a trauma patient

OBJECTIVE

To describe the first reported case of bacteremia and empyema caused by Shewanella algae and summarize the existing literature on Shewanella human infection.

CASE SUMMARY

A 25-year-old healthy male was shot through the chest into the abdomen and fled into an adjacent body of seawater. He underwent surgical repair of his injuries, including pleural decortication. Leukocytosis, bandemia, and copious yellow bronchorrhea led to cultures; piperacillin/tazobactam and vancomycin were started for broad-spectrum empiric management based on the local intensive care unit antibiogram. Blood and pleural fluid cultures revealed S algae. Sputum cultures grew methicillin-sensitive Staphylococcus aureus and Haemophilus influenzae. He was successfully managed with an empiric and then tailored antibiotic regimen.

DISCUSSION

Shewanella algae is a rare Gram-negative bacillus that has infrequently been reported to cause infection. It is found predominantly in men. Shewanella algae infections span bacteremia to necrotizing soft tissue infection and are associated with injury and seawater exposure. Shewanella is susceptible to the majority of third- and fourth-generation cephalosporins, aminoglycosides, chloramphenicol, erythromycin, aztreonam, and fluoroquinolones, but are less predictably susceptible to tetracycline and trimethoprim/sulfamethoxazole and carbapenem agents. Shewanella infection is associated with medical comorbidities, in particular, renal failure and cardiovascular disease.

CONCLUSIONS

To our knowledge, this is the first case report of bacteremia and empyema caused by S algae. Such a case involving a young healthy individual should encourage health care providers to be aware of the potential infections caused by unusual pathogens, and to employ appropriate empiric antibiotic therapy based on reported sensitivity profiles. Based on available susceptibilities, we recommend using a third or fourth-generation cephalosporin as first-line pharmacologic management with regimen de-escalation based on culture-derived data.

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.

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.

Emerging infections: shewanella - a series of five cases

Background:

Shewanella spp. are unusual cause of disease in humans; however, reports of Shewanella infections have been increasing. Shewanella is a ubiquitous organism that has been isolated from many foods, sewage, and both from fresh and salt water. Earlier it was named as Pseudomonas putrefaciens or Shewanella putrefaciens. There are several reports describing this organism causing human infections such as cellulitis, abscesses, bacteremia, wound infection, etc. It is oxidase and catalase-positive non-fermenter gram-negative rod that produces hydrogen sulfide.

Aims:

The study was conducted to identify Shewanella spp., which was wrongly reported as Pseudomonas spp.

Materials and Methods:

Clinical samples were cultured as per standard clinical laboratory procedure. We tested the non-lactose-fermenting colonies for oxidase positivity. Oxidase-positive colony was inoculated in triple sugar iron slant (TSI) to know the hydrogen sulfide production. Hydrogen sulfide positive colonies were further tested for citrate, urease, indole, and amino acid decarboxylation and acid and gas production from sugars.

Results:

Five isolates identified as Pseudomonas spp. during preliminary testing were proved to be Shewanella spp. on further testing.

Conclusions:

It will help in better understanding the epidemiology, pathogenesis and risk factors associated with these and prevention of the rare pathogenic organisms.