Primary bacteraemia caused by Rhizobium radiobacter in a patient with solid tumours

Bacteria of Zoonotic Interest Identified on Edible Freshwater Fish Imported to Australia

Previous research has shown that freshwater edible fish imported into Australia are not compliant with Australian importation guidelines and as a result may be high risk for bacterial contamination. In the present study, the outer surface of imported freshwater fish were swabbed, cultured, confirmatory tests performed and antimicrobial patterns investigated. Channidae fish (Sp. A/n = 66) were contaminated with zoonotic Salmonella sp./Staphylococcus aureus (n = 1/66) and other bacteria implicated in cases of opportunistic human infection, these being Pseudomonas sp. (including P. mendocina and P. pseudoalcaligenes (n = 34/66)); Micrococcus sp. (n = 32/66); Comamonas testosteroni (n = 27/66) and Rhizobium radiobacter (n = 3/66). Pangasiidae fish (Species B/n = 47) were contaminated with zoonotic Vibrio fluvialis (n = 10/47); Salmonella sp. (n = 6/47) and environmental bacteria Micrococcus sp. (n = 3/47). One sample was resistant to all antimicrobials tested and is considered to be Methicillin Resistant S. aureus. Mud, natural diet, or vegetation identified in Sp. A fish/or packaging were significantly associated with the presence of Pseudomonas spp. The study also showed that visibly clean fish (Sp. B) may harbour zoonotic bacteria and that certain types of bacteria are common to fish groups, preparations, and contaminants. Further investigations are required to support the development of appropriate food safety recommendations in Australia.

Central line-associated Rhizobium radiobacter bloodstream infection in two allogeneic hematopoietic cell transplant recipients

INTRODUCTION

Rhizobium radiobacter is a gram-negative, opportunistic phytopathogen that rarely causes human infections. We report two cases of Rhizobium radiobacter central line-associated bloodstream infection (CLABSI) in allogeneic hematopoietic cell transplantation (alloHCT) recipients. We review previous reports and common microbiological characteristics associated with this organism.

CASE REPORTS

Two adult males developed R. radiobacter CLABSIs at day +81 and day +77 post-alloHCT. Patient one was asymptomatic on presentation while patient two was febrile. One patient had a polymicrobial infection, which has not been previously described. The presence of high-level ceftazidime resistance in both patients suggests third-generation cephalosporin resistance may be more common than previously recognized.

MANAGEMENT AND OUTCOME

For both patients, microbiologic clearance was achieved through peripherally inserted central catheter removal and initiation of intravenous cefepime. Antibiotic therapy was narrowed to oral levofloxacin for a total 14-day course from the time of first negative blood culture. There has been no subsequent recurrence of R. radiobacter infection at 12 and 5 months of follow-up for patients one and two, respectively.

DISCUSSION

These two cases add to the scant literature characterizing R. radiobacter infection following alloHCT. Immunosuppressive agents for graft-versus-host disease prophylaxis may have predisposed these patients to R. radiobacter infection. Our reports, and previously reported cases, suggest R. radiobacter exhibits low virulence, mild symptom burden, and does not confer a high mortality risk. In the alloHCT setting, further accumulation of cases is needed to aid in understanding clinical features and characteristics of R. radiobacter infection.

The risk of transmitting antibiotic resistance through endophytic bacteria

Antibiotic resistance is a global human health threat distributed across humans, animals, plants, and the environment. Under the One-Health concept (humans, animals, and environment), the contamination of water bodies and soil by antibiotic-resistant bacteria cannot be dissociated from its potential transmission to humans. Edible plants can be colonized by a vast diversity of bacteria, representing an important link between the environment and humans in the One-Health triad. Based on multiple examples of bacterial groups that comprise endophytes reported in edible plants, and that have close phylogenetic proximity with human opportunistic pathogens, we argue that plants exposed to human-derived biological contamination may represent a path of transmission of antibiotic resistance to humans.

Septic shock caused by Rhizobium radiobacter in an elderly woman: A case report

RATIONALE

Rhizobium radiobacter is a Gram-negative pathogen present in soil and plants. Cases of R radiobacter infection in immunocompromised hosts have been sporadically reported. However, septic shock caused by R radiobacter is rarely seen.

PATIENT CONCERNS

Here, we describe an elderly patient with a rapid progression of watery diarrhea, anorexia, fever, weakness, oliguria, and shock. Blood results showed increased total white blood cell count and C-reactive protein. Arterial blood gas results showed hypoxia and elevated lactate level. The Sequential Organ Failure Assessment score was 11. Blood culture at admission showed Gram-negative bacteria, which were later confirmed as R radiobacter.

DIAGNOSIS

Septic shock caused by R Radiobacter.

INTERVENTIONS

The patient was treated with intravenous cefoperazone/sulbactam and sequential oral levofloxacin.

OUTCOMES

The patient recovered completely.

CONCLUSION

R radiobacter may be considered as a potential opportunistic pathogen that may cause severe sepsis in elderly patients, especially those with multiple underlying diseases.

Infections Caused by Antimicrobial Drug-Resistant Saprophytic Gram-Negative Bacteria in the Environment

Background

Drug-resistance genes found in human bacterial pathogens are increasingly recognized in saprophytic Gram-negative bacteria (GNB) from environmental sources. The clinical implication of such environmental GNBs is unknown.

Objectives

We conducted a systematic review to determine how often such saprophytic GNBs cause human infections.

Methods

We queried PubMed for articles published in English, Spanish, and French between January 2006 and July 2014 for 20 common environmental saprophytic GNB species, using search terms “infections,” “human infections,” “hospital infection.” We analyzed 251 of 1,275 non-duplicate publications that satisfied our selection criteria. Saprophytes implicated in blood stream infection (BSI), urinary tract infection (UTI), skin and soft tissue infection (SSTI), post-surgical infection (PSI), osteomyelitis (Osteo), and pneumonia (PNA) were quantitatively assessed.

Results

Thirteen of the 20 queried GNB saprophytic species were implicated in 674 distinct infection episodes from 45 countries. The most common species included Enterobacter aerogenes, Pantoea agglomerans, and Pseudomonas putida. Of these infections, 443 (66%) had BSI, 48 (7%) had SSTI, 36 (5%) had UTI, 28 (4%) had PSI, 21 (3%) had PNA, 16 (3%) had Osteo, and 82 (12%) had other infections. Nearly all infections occurred in subjects with comorbidities. Resistant strains harbored extended-spectrum beta-lactamase (ESBL), carbapenemase, and metallo-β-lactamase genes recognized in human pathogens.

Conclusion

These observations show that saprophytic GNB organisms that harbor recognized drug-resistance genes cause a wide spectrum of infections, especially as opportunistic pathogens. Such GNB saprophytes may become increasingly more common in healthcare settings, as has already been observed with other environmental GNBs such as Acinetobacter baumannii and Pseudomonas aeruginosa.

Primary Bacteremia Caused by Rhizobium radiobacter in Neonate: A Rare Case Report

Rhizobium radiobacter is a gram-negative tumourigenic plant pathogen that rarely causes infections in humans. Rhizobium radiobacter has a strong predilection to cause infection particularly in those patients who have long standing indwelling foreign devices. Herewith we report a rare case of Rhizobium radiobacter bacteremia in a new born baby without other risk factors. The patient was successfully treated with gentamicin and imipenem. To the best of our knowledge this is the first documented case of R. radiobacter from India causing neonatal infection.

Treatment of Rhizobium radiobacter bacteremia in a critically ill trauma patient

OBJECTIVE

To report the first case of Rhizobium radiobacter bacteremia in a critically ill trauma patient.

CASE SUMMARY

A 36-year-old female trauma patient hospitalized at The Regional Medical Center at Memphis developed bacteremia due to Rhizobium radiobacter on hospital day 9. The central line catheter tip culture from the same hospital day was negative. No source for the R radiobacter bacteremia was identified. Empirical and definitive antibiotic therapy consisted of cefepime 2 g intravenously every 8 hours for at total of 8 days. On completion of antibiotics, the patient demonstrated clinical resolution by immediate defervescence and gradual normalization of her white blood cell count. She demonstrated microbiologic success of therapy with negative blood cultures on hospital days 22, 34, 45, and 61. She was discharged on hospital day 80.

DISCUSSION

Rhizobium species are common soil and plant pathogens that rarely cause infections in humans. Previous reports of Rhizobium infections have been in immunocompromised patients; generally those with cancer or HIV infection. Intravenous catheters have commonly been cited as the source of infection. The trauma patient in this case constitutes a unique presentation of R radiobacter bacteremia when compared with other case reports. Her indwelling catheter was not the source of her infection, and her only identifiable risk factor for R radiobacter infection was hospitalization. However, she did possess potential reasons for development of an infection with an unusual organism such as R radiobacter. Potential immune modulating therapies included blood transfusions, opioid analgesics, benzodiazepines, general anesthetics, and surgical procedures. Finally, trauma itself has been associated with some degree of immunosuppression. All these issues may have placed the patient in this case at risk of an opportunistic infection like R radiobacter.

CONCLUSION

Based on this case, R radiobacter may be considered a potential pathogen causing bacteremia in critically ill trauma patients.

Three cases of post-cataract surgery endophthalmitis due to Rhizobium (Agrobacterium) radiobacter

We present three unrelated post-cataract surgery endophthalmitis cases caused by Rhizobium radiobacter, hospitalized in three different hospitals. Early diagnosis was obtained in two cases by bacterial DNA detection in vitreous samples. All patients recovered from infection, but pars plana vitrectomy was needed in two patients due to rapid clinical deterioration.

Catheter associated bloodstream infection caused by R. radiobacter

Rhizobium radiobacter is a gram negative bacillus that is infrequently recognized in clinical specimens but is emerging as an opportunistic human pathogen. Infections due to Rhizobium radiobacter are strongly related to the presence of foreign plastic material and effective treatment often requires removal of the device. We report a case of R. radiobacter bloodstream infection associated with a central venous catheter which was easily controlled by antimicrobial treatment and did not require removal of intravascular device. To the best of our knowledge, this is the first case report from India implicating R. radiobacter as a cause of human infection.

Pseudo-outbreak of Rhizobium radiobacter infection resulting from laboratory contamination of saline solution

We report a pseudo-outbreak of Rhizobium radiobacter infections resulting from contamination by a saline dispenser in the microbiology laboratory. Isolates from clinical specimens had identical antimicrobial susceptibilities and electrophoretic fingerprints. The episode resolved with autoclaving of the dispenser. This demonstrates the importance of timely, thorough investigation of unusual organisms, particularly when they appear as a cluster.

Agrobacterium radiobacter bacteremia in oncologic and geriatric patients: presentation of two cases and review of the literature

INTRODUCTION

We report here two cases of Agrobacterium radiobacter bacteremia. These cases were observed at the same institution over a short time period (3 months).

CASE REPORTS

The first patient was a female cancer patient receiving third-line chemotherapy for ovarian carcinoma. When she developed bacteremia, she was neutropenic and had an indwelling catheter that was removed as part of the treatment. The second case was a geriatric patient admitted from home with bacteremia, clinical signs of septic shock, and concomitant acute cholecystitis.

OUTCOME

Both patients responded promptly and completely to antibiotherapy. No recurrence was observed.

Agrobacterium tumefaciens-induced bacteraemia does not lead to reporter gene expression in mouse organs

Agrobacterium tumefaciens is the main plant biotechnology gene transfer tool with host range which can be extended to non-plant eukaryotic organisms under laboratory conditions. Known medical cases of Agrobacterium species isolation from bloodstream infections necessitate the assessment of biosafety-related risks of A. tumefaciens encounters with mammalian organisms. Here, we studied the survival of A. tumefaciens in bloodstream of mice injected with bacterial cultures. Bacterial titers of 10(8) CFU were detected in the blood of the injected animals up to two weeks after intravenous injection. Agrobacteria carrying Cauliflower mosaic virus (CaMV) 35S promoter-based constructs and isolated from the injected mice retained their capacity to promote green fluorescent protein (GFP) synthesis in Nicotiana benthamiana leaves. To examine whether or not the injected agrobacteria are able to express in mouse organs, we used an intron-containing GFP (GFPi) reporter driven either by a cytomegalovirus (CMV) promoter or by a CaMV 35S promoter. Western and northern blot analyses as well as RT-PCR analysis of liver, spleen and lung of mice injected with A. tumefaciens detected neither GFP protein nor its transcripts. Thus, bacteraemia induced in mice by A. tumefaciens does not lead to detectable levels of genetic transformation of mouse organs.

Rhizobium radiobacter as an opportunistic pathogen in central venous catheter-associated bloodstream infection: case report and review

Rhizobium radiobacter is an uncommon opportunistic pathogen present in soil. It has been particularly associated with indwelling intravascular devices in immunocompromised patients. In this report, we summarise the case of a patient with multiple myeloma who developed R. radiobacter bacteraemia during autologous stem cell leucopheresis. Retrospective investigation revealed exposure to soil after central venous catheter placement for chemotherapy and leucopheresis access. This is the first reported case of R. radiobacter bacteraemia following probable colonisation of the catheter from soil exposure. We further review the existing literature to delineate prevention and treatment recommendations for line-associated R. radiobacter infections.