Complete sequence of carbapenem-resistant Ralstonia mannitolilytica clinical isolate co-producing novel class D β-lactamase OXA-1176 and OXA-1177 in Japan

In 2020, the Ralstonia mannitolilytica strain JARB-RN-0044 was isolated from a midstream urine sample of an elderly hospitalized patient in Japan and was highly resistant to carbapenem (i.e., imipenem, meropenem, and doripenem). Whole-genome sequencing revealed that the complete genome consists of two replicons, a 3.5-Mb chromosome and a 1.5-Mb large non-chromosomal replicon which has not been reported in R. mannitolilytica, and referred to as the "megaplasmid" in this study based on Cluster of Orthologous Group of proteins functional analysis. The strain JARB-RN-0044 harbored two novel OXA-60 and OXA-22 family class D β-lactamase genes blaOXA-1176 and blaOXA-1177 on the megaplasmid. Cloning experiments indicated that Escherichia coli recombinant clone expressing blaOXA-1176 gene showed increased minimum inhibitory concentrations (MICs) of imipenem, meropenem, and doripenem, indicating that blaOXA-1176 gene encodes carbapenemase. In contrast, E. coli recombinant clone expressing blaOXA-1177 gene showed increased MICs of piperacillin and cefazolin, but not of carbapenem. Interestingly, the 44.6 kb putative prophage region containing genes encoding phage integrase, terminase, head and tail protein was identified in the downstream region of blaOXA-1176 gene, and comparative analysis with some previously reported R. mannitolilytica isolates revealed that the prophage region was unique to strain JARB-RN-0044. The existence of a highly carbapenem-resistant R. mannitolilytica isolate may raise human health concerns in Japan, where the population is rapidly aging.IMPORTANCERalstonia mannitolilytica is an aerobic non-fermenting Gram-negative rod commonly found in aquatic environments and soil. The bacteria can occasionally cause severe hospital-acquired bloodstream infections in immunocompromised patients and it has been recently recognized as an emerging opportunistic human pathogen. Furthermore, some R. mannitolilytica isolates are resistant to various antimicrobial agents, including β-lactams and aminoglycosides, making antimicrobial therapy challenging and clinically problematic. However, clinical awareness of this pathogen is limited. To our knowledge, in Japan, there has been only one report of a carbapenem-resistant R. mannitolilytica clinical isolate from urine by Suzuki et al. in 2015. In this study, whole-genome sequencing analysis revealed the presence and genetic context of novel blaOXA-1176 and blaOXA-1177 genes on the 1.5 Mb megaplasmid from highly carbapenem-resistant R. mannitolilytica isolate and characterized the overall distribution of functional genes in the chromosome and megaplasmid. Our findings highlight the importance of further attention to R. mannitolilytica isolate in clinical settings.

Decolorization potential of malachite green by Ralstonia mannitolilytica isolated from Indonesian cassava-based fermented food tapai

Pollution due to textile dye effluent mishandling is hazardous to ecosystems and to the living beings inhabiting them. This can cause retarded photosynthesis, disrupted fish day/night cycles, unbalanced bacterial populations, and decreased oxygen concentration in contaminated water, leading to low habitability. In this study, we aimed to isolate and characterize the microorganisms found in Indonesian cassava-based fermented food tapai starter cultures as a source of potential microbes for the biological remediation of textile dye pollutants. Microorganisms in the tapai starter culture were screened for their decolorization activity via spread-culture inoculation on a solid growth medium supplemented with textile dyes. Isolated microorganisms were selected based on their ability to secrete textile dye-decolorizing extracellular enzymes via increased light penetration after incubation of the cell-free supernatant (CFS) containing extracellular enzymes in textile dye solutions. Isolate JSP1 was the only bacterium capable of producing malachite green (MG)-decolorizing extracellular enzymes, which enabled it to survive and decolorize MG up to 375 ppm. Moreover, isolate JSP1 CFS was able to optimally decolorize 75% of MG at 100 ppm, but its activity was diminished at concentrations > 350 ppm. Colony and cellular morphology, biochemistry, and 16S rRNA tests revealed that the isolate was of Ralstonia mannitolilytica. Therefore, R. mannitolilytica isolate JSP1 may be a potential bioremediation agent for MG.

Clinical Manifestation of Ralstonia mannitolilytica Infection in Pediatric Patients and Epidemiological Investigation of Outbreaks

BACKGROUND

Ralstonia mannitolilytica is a causative organism of nosocomial infections, particularly associated with contaminated water, and resistant to various antibiotics, including carbapenems. Several clusters of R. mannitolilytica infections appeared in children at our institute from August 2018 to November 2019.

METHODS

From March 2009 to March 2023, all patients admitted to Asan Medical Center Children's Hospital in Seoul, Korea, with culture-confirmed R. mannitolilytica and corresponding clinical signs of infection were identified. Epidemiological and environmental investigations were conducted. Polymerase chain reaction (PCR) was performed for the genes of OXA-443 and OXA-444 on R. mannitolilytica isolates.

RESULTS

A total of 18 patients with R. mannitolilytica infection were included in this study, with 94.4% (17/18) and 5.6% (1/18) being diagnosed with pneumonia and central line-associated bloodstream infection, respectively. All-cause 30-day mortality rate was 61.1% (11/18), and seven of the fatal cases were caused by R. mannitolilytica infection itself. The resistance rates to meropenem and imipenem werew 94.4% (17/18) and 5.6% (1/18), respectively. Although four out of nine meropenem-resistant R. mannitolilytica isolates had positive PCR results for OXA-443 and OXA-444 genes, there were no significant differences in antimicrobial susceptibility patterns. Environmental sampling identified R. mannitolylica at two sites: a cold-water tap of a water purifier and an exhalation circuit of a patient mechanical ventilator. After implementing and improving adherence to infection control policies, no additional R. mannitolilytica infection cases have been reported since December 2019.

CONCLUSION

R. mannitolilytica can cause life-threatening infections with high mortality in fragile pediatric populations. To prevent outbreaks, healthcare workers should be aware of R. mannitolilytica infections and strive to comply with infection control policies.

Rare case of Ralstonia mannitolilytica peritonitis in an adult peritoneal dialysis patient

Peritonitis is a common complication of peritoneal dialysis (PD) usually caused by skin-dwelling Gram-positive bacteria and Gram-negative bacteria colonizing the gut and urinary tract. Occasionally, uncommon bacteria can cause peritonitis in PD patients. We describe a case of Ralstonia mannitolilytica peritonitis in a 67-year-old woman who has been on PD for more than 10 years with no prior episodes of peritonitis. To our knowledge, this is the first reported case of Ralstonia peritonitis in the United States. She initially presented with abdominal tenderness, right flank pain, and cloudy output from her nephrostomy tube. PD fluid and urine cultures grew E. coli which responded to treatment. However, her symptoms recurred after completion of antibiotic therapy with PD fluid growing Ralstonia species. She again responded to intraperitoneal antibiotics but had recurrence of symptoms after the completion of her second course of antibiotics. PD fluid grew Ralstonia mannitolilytica resistant to the prior antibiotic regimen. The PD catheter was removed, and she was transitioned to hemodialysis. Subsequent treatment led to the resolution of her symptoms. Ralstonia species are Gram-negative bacteria that are prevalent in water supplies and can form biofilms. They have been known to cause infection particularly in neonates, immunocompromised patients, or patients in intensive care. In our patient, prior antibiotic treatment for E. coli peritonitis is likely to have contributed to the development of Ralstonia peritonitis. Clinical improvement after removal of the PD catheter revealed that seeding from the PD catheter was the likely culprit for the recurrent infections.

Ralstonia mannitolilytica as a rare cause of spondylodiscitis following endoscopic lumbar discectomy- A report of two cases

Ralstonia mannitolilytica is a low-virulence, gram-negative bacillus which causes opportunistic infections in immunosuppressed patients. Postoperative spondylodiscitis by R. mannitolilytica has not been reported so far. We report the management of two cases of postoperative spondylodiscitis caused by Ralstonia mannitolilytica presenting to our center within a span of one month following endoscopic lumbar discectomy at a different center. They were managed successfully by surgical debridement and appropriate antibiotics. In these two cases of R.mannitolilytica spondylodiscitis, prompt detection, and intensive treatment resulted in satisfactory outcomes in terms of fulfilling the purpose of the original surgery.

Spherical pneumonia caused by Ralstonia mannitolilytica: a case report and literature review

BACKGROUND

Spherical pneumonia is an extremely rare condition that is difficult to diagnose. It is a specific type of lung infection that often manifests as a round or round-like mass on chest imaging. Spherical pneumonia is easily misdiagnosed as a pulmonary tumor; therefore, awareness of this disease must be strengthened.

CASE PRESENTATION

The patient was a 29-year-old female who had persistent cough and sputum for approximately 1 month and fever for 5 days. Chest computed tomography (CT) at our hospital revealed a mass in the lower lobe of the right lung near the hilar region, with obstructive pulmonary atelectasis and obstructive pneumonia. Although lung cancer was suspected, Ralstonia mannitolilytica was detected by metagenomic next-generation sequencing (mNGS) of bronchoalveolar lavage fluid, and no cancer cells or Mycobacterium tuberculosis were detected. Finally, the patient was diagnosed with spherical pneumonia caused by R. mannitolilytica. Anti-infective treatment, symptomatic treatment, and administration of a traditional Chinese medicine decoction were performed based on the syndrome differentiation. After 10 days of treatment, chest CT revealed few lesions in the lower lobe of the right lung, which were significantly reduced compared with those in the past.

CONCLUSIONS

Spherical pneumonia caused by R. mannitolilytica has not yet been reported and differential diagnosis is key in clinical diagnosis. When spherical pneumonia is difficult to diagnose, mNGS may be a better alternative.

Postoperative cerebrospinal fluid infection by Ralstonia mannitolilytica: Two case reports and a literature review

Background

Ralstonia species are Gram-negative bacilli that are commonly found in moist environments, such as water and soil. They are opportunistic human pathogens, particularly found among immunocompromised patients, and are an infrequent cause of infection. The difficulty in correctly identifying and differentiating between Ralstonia species members using routine biochemical methods as well as their resistance to many classes of antibiotics poses a specific diagnostic and therapeutic challenge.

Case Description

We report two cases from our neurosurgical unit complicated by postoperative cerebrospinal fluid infection caused by Ralstonia Mannitolilytica that posed a therapeutic challenge.

Conclusion

Our hypothesis is contaminated irrigation fluids might be a significant cause of post-operative meningitis and prolonged hospital stay.

Antimicrobial Treatment on a Catheter-Related Bloodstream Infection (CRBSI) Case Due to Transition of a Multi-Drug-Resistant Ralstonia mannitolilytica from Commensal to Pathogen during Hospitalization

Despite its commonly overlooked role as a commensal, Ralstonia mannitolilytica becomes an emerging global opportunistic human pathogen and a causative agent of various infections and diseases. In respiratory illnesses, including cystic fibrosis and chronic obstructive pulmonary disease (COPD), R. mannitolilytica is also identified presumably as colonizer. In this study, one distinctive clone of R. mannitolilytica was firstly identified as colonizer for the first 20 days during hospitalization of a patient. It was then identified as a causative agent for catheter-related bloodstream infection with negative identification after effective treatment, verifying its transition from commensal to pathogen. In conclusion, we provide convincing evidence that during hospitalization of a patient, R. mannitolilytica transitioned from commensal to pathogen in the respiratory tract leading to catheter-related bloodstream infection (CRBSI).

Septic Shock After Kidney Transplant: A Rare Bloodstream Ralstonia mannitolilytica Infection

Background

Ralstonia mannitolilytica, an emerging opportunistic pathogen, can infect immunocompromised patients but is a rare cause of severe sepsis and septic shock in kidney transplant recipients (KTRs).

Case Presentation

We present a case of septic shock after renal transplant in a 41-year-old male, which was finally proven to be caused by Ralstonia mannitolilytica through blood cultures and mass spectrometric analysis following the negative result of metagenomic next-generation sequencing (mNGS). He was finally cured after the application of sensitive antibiotics (sulfamethoxazole-trimethoprim, amikacin and piperacillin-tazobactam) based on the drug sensitivity test results. The patient had a satisfactory recovery with no complications during a 6-month follow-up period.

Conclusion

This study highlights that Ralstonia mannitolilytica is an easily overlooked cause of septic shock in KTRs requiring a detailed inquiry of medical history with inflammatory markers monitored closely. Traditional blood cultures still should be taken seriously. It also provides a cautionary tale that negative results of mNGS have to be interpreted with caution.

Sepsis Due to Bloodstream Ralstonia mannitolilytica Infection After Surgical Treatment of Perianal Abscess: A Case Report

Background

Ralstonia mannitolilytica can cause opportunistic infections. Reports on this pathogen identified in the bloodstream are rare worldwide, especially in China.

Case Description

We describe a 48-year-old man who developed sepsis due to bloodstream Ralstonia mannitolilytica infection after surgery for a perianal abscess. His condition deteriorated into multiple organ dysfunction syndromes until susceptible antibiotics (ceftriaxone and levofloxacin) were administrated based on the drug sensitivity test results. The patient had a satisfactory recovery with no complications during a 6-month follow-up period.

Conclusion

Ralstonia mannitolilytica blood-borne infection in patients evolves rapidly. The inconsistent sensitivity to antibiotics makes timely treatment difficult and can lead to serious complications. We report the clinical presentations and treatment outcomes for this patient here to remind clinicians about this rare opportunistic pathogen and to highlight the importance of bacterial culture, especially for immunocompromised patients.

Ralstonia mannitolilytica sepsis after elective cesarean delivery: a case report

Background

Ralstonia mannitolilytica, a newly emerging opportunistic pathogen worldwide, has been reported to be responsible for human pneumonia, septicemia and meningitis. This is the first report of a case of Ralstonia mannitolilytica sepsis after elective cesarean delivery.

Case presentation

A 25-year-old woman, gravida 1 para 0, was scheduled for an elective cesarean delivery at 39^+ 1 weeks of gestation. Sudden high fever and decreased blood pressure occurred a short time after the operation. Ralstonia mannitolilytica was identified in her blood culture 5 days after the operation. Based on the presence of sepsis and septic shock, massive fluid replacement, blood transfusion, vasoactive agents, imipenem/cilastatin and cefoperazone sulbactam sodium were applied. She was discharged after intensive care without complications.

Conclusions

Although the incidence of sepsis due to Ralstonia mannitolilytica is relatively low, once infection occurs in a puerpera, severe symptoms develop abruptly. Thus, prompt diagnosis and appropriate treatment are key to the cure.

Ralstonia mannitolilytica sepsis in neonatal intensive care unit - Be(a)ware of the multidrug resistant nosocomial bug

Ralstonia mannitolilytica, an emerging opportunistic pathogen is rarely isolated in neonatal units. We have elaborated our experience of managing its recent septic outbreak affecting four neonates in our intensive care unit over a span of five days. Three of the four had extremely low birth weight and had secondary clinical deterioration in the form of recurrent apnoea requiring intubation. All had thrombocytopenia. Their median age at clinical deterioration was 8 (4-12) days. The organism was multidrug resistant, but uniformly sensitive to flouroquinolones and co-trimoxazole, on which all recovered. Environmental samples were negative for the organism. There were no further positive cases. Early recognition and appropriate choice of drug will aid in fast recovery.

Ralstonia mannitollylitica endocarditis: A case report

Ralstonia mannitolilytica (R. mannitolilytica.) is an emerging aerobic Gram-negative bacteria causing infection among immunocompromised patients. R. mannitolilytica, has been described in hospital outbreaks, mainly as bloodstream infection, but also as meningitis, hemoperitoneum infection and post renal transplant infection. We describe the first reported case of R. mannitolilytica infective endocarditis.

Outbreak of Ralstonia mannitolilytica bacteraemia in patients undergoing haemodialysis at a tertiary hospital in Pretoria, South Africa

Background

Ralstonia species are Gram-negative bacilli of low virulence. These organisms are capable of causing healthcare associated infections through contaminated solutions. In this study, we aimed to determine the source of Ralstonia mannitolilytica bacteraemia in affected patients in a haemodialysis unit.

Methods

Our laboratory noted an increase in cases of bacteraemia caused by Ralstonia mannitililytica between May and June 2016. All affected patients underwent haemodialysis at the haemodialysis unit of an academic hospital. The reverse osmosis filter of the haemodialysis water system was found to be dysfunctional. We collected water for culture at various points of the dialysis system to determine the source of the organism implicated. ERIC-PCR was used to determine relatedness of patient and environmental isolates.

Results

Sixteen patients were found to have Ralstonia mannitolilytica bacteraemia during the outbreak period. We cultured Ralstonia spp. from water collected in the dialysis system. This isolate and patient isolates were found to have the identical molecular banding pattern.

Conclusions

All patients were septic and received directed antibiotic therapy. There was 1 mortality. The source of the R. mannitolilytica infection in these patients was most likely the dialysis water as the identical organism was cultured from the dialysis water and the patients. The hospital management intervened and repaired the dialysis water system following which no further cases of R. mannitolilytca infections were detected. A multidisciplinary approach is required to control healthcare associated infections such as these. Routine maintenance of water systems in the hospital is essential to prevent clinical infections with R.mannitolilytica.

Ralstonia mannitolilytica sepsis: a case report

Background

Ralstonia mannitolilytica is an emerging opportunistic pathogen that is associated with severe disease, including septic shock, meningitis, and renal transplant infections. Reports on this pathogen are limited, however, especially on the African continent.

Case presentation

A 2-year-old Akan child was presented to a hospital in the northeastern part of Ghana with a 1-week history of fever and chills. We identified Ralstonia mannitolilytica in her blood culture using both conventional and 16S ribosomal deoxyribonucleic acid (rDNA) techniques. The patient’s condition improved clinically upon treatment with cefuroxime.

Conclusion

Our report highlights the potential of Ralstonia mannitolilytica to cause sepsis and thus emphasizes the need for improved laboratory diagnosis and evidence for use of appropriate antibiotics in rural settings of Africa, where presumptive treatment using antimicrobial agents is rife.

A case of persistent bacteraemia by Ralstonia mannitolilytica and Ralstonia pickettii in an intensive care unit

The Ralstonia spp. genus is a group of non-fermentative, Gram-negative bacteria often resistant to many antibiotics, which are emerging as opportunistic pathogens frequently associated with infections in hospital settings. We present herein a case of combined R. pickettii and R. mannitolilytica persisting and relapsing bacteraemia, possibly caused by a septic arterial thrombosis secondary to the rupture of an internal carotid artery aneurysm. Microbiology studies showed that both Ralstonia isolates produced biofilm and carried class D oxacillinase genes. When confronted with infections caused by members of the Ralstonia genus, identification to the species level is crucial for correct clinical management, as the two species show different antibiotic susceptibility patterns.

Outbreak of Ralstonia mannitolilytica in Hemodialysis Unit: A Case Series

Ralstonia mannitolilytica is a Gram-negative soil bacteria. It is an emerging opportunistic pathogen in hospital-acquired infections. Maintenance hemodialysis patients at Manipal Hospital Outpatient Haemodialysis unit, Bengaluru, witnessed an outbreak of R. mannitolilytica infection between October 2016 and November 2016. Five patients were infected and one of them presented with infective endocarditis. All patients were successfully treated with antibiotic according to culture and sensitivity pattern. Immediately following the outbreak, environmental sampling was done. The culture from sterile water was positive for R. mannitolilytica growth. The Department of Infection Control ordered for discarding the whole batch of sterile water followed by water treatment with shock chlorination and room disinfection. Following implementation of the same, the outbreak of R. mannitolilytica infection was controlled. R. mannitolilytica infections are hospital acquired, affecting mainly immunocompromised patients. The disease onset and progression is rapid. Early identification of the organism and treatment with appropriate antibiotics is important.

A rare case of Ralstonia mannitolilytica infection in an end stage renal patient on maintenance dialysis during municipal water contamination

Ralstonia mannitolilytica is a gram negative soil bacterium. Ralstonia infection though rare, has become the emerging nosocomial pathogens in hospital settings. Various clinical manifestations had been described as well as the mode of transmission. Despite its low virulence factor, it is able to survive under harsh condition and this may potentially cause significant morbidity and mortality especially in immunocompromised patients. Outbreak of Ralstonia mannitolilytica infections in the hospital are typically associated with contaminated medical supplies or instruments. We described here a case of Ralstonia mannitolilytica infection in a dialysis patient that occurred during the municipal reservoir water contamination crisis. In this report, we will also describe the behaviour of Ralstonia genus and its 4 main species, namely R. pickettii, R. solanacearum, R. insidiosa, and R. mannitolilytica and the choices of antibiotic therapy based on literature review.

Ralstonia mannitolilytica infections in an oncologic day ward: description of a cluster among high-risk patients

BACKGROUND

Ralstonia spp, an environmental microorganism, has been occasionally associated with healthcare infections. The aim of this study was to investigate an outbreak caused by Ralstonia mannitolilytica in oncology patients.

METHODS

Case definition: Oncology outpatients attending a day ward, with positive blood and/or central venous catheter (CVC) culture for Ralstonia spp from September 2013 - June 2014. We analysed medical records, procedures and environmental samples. R. mannitolilytica was identified by 16S rRNA sequencing, and typed by Pulsed Field Gel Electrophoresis (PFGE); resistance to carbapenemes was investigated by phenotypic and molecular methods.

RESULTS

The patients (N = 22) had different malignancies and received different therapy; all had a CVC and 16 patients presented chills and/or fever. R. mannitolilytica was isolated from both blood and CVC (n = 12) or only blood (n = 6) or CVC tips (n = 4). The isolates had indistinguishable PFGE profile, and showed resistance to carbapenems. All the isolates were negative for carbapenemase genes while phenotypic tests suggests the presence of an AmpC β-lactamase activity,responsible for carbapenem resistance. All patients had had CVC flushed with saline to keep the venous access pervious or before receiving chemotherapy at various times before the onset of symptoms. After the first four cases occurred, the multi-dose saline bottles used for CVC flushing were replaced with single-dose vials; environmental samples were negative for R. mannitolilytica.

CONCLUSIONS

Although the source of R. mannitolilytica remains unidentified, CVC flushing with contaminated saline solution seems to be the most likely origin of R. mannitolilytica CVC colonization and subsequent infections. In order to prevent similar outbreaks we recommend removal of any CVC that is no longer necessary and the use of single-dose solutions for any parenteral treatment of oncology patients.

Development of an in vitro Assay, Based on the BioFilm Ring Test®, for Rapid Profiling of Biofilm-Growing Bacteria

Microbial biofilm represents a major virulence factor associated with chronic and recurrent infections. Pathogenic bacteria embedded in biofilms are highly resistant to environmental and chemical agents, including antibiotics and therefore difficult to eradicate. Thus, reliable tests to assess biofilm formation by bacterial strains as well as the impact of chemicals or antibiotics on biofilm formation represent desirable tools for a most effective therapeutic management and microbiological risk control. Current methods to evaluate biofilm formation are usually time-consuming, costly, and hardly applicable in the clinical setting. The aim of the present study was to develop and assess a simple and reliable in vitro procedure for the characterization of biofilm-producing bacterial strains for future clinical applications based on the BioFilm Ring Test® (BRT) technology. The procedure developed for clinical testing (cBRT) can provide an accurate and timely (5 h) measurement of biofilm formation for the most common pathogenic bacteria seen in clinical practice. The results gathered by the cBRT assay were in agreement with the traditional crystal violet (CV) staining test, according to the κ coefficient test (κ = 0.623). However, the cBRT assay showed higher levels of specificity (92.2%) and accuracy (88.1%) as compared to CV. The results indicate that this procedure offers an easy, rapid and robust assay to test microbial biofilm and a promising tool for clinical microbiology.

Ralstonia mannitolilytica-Induced Septicemia and Homology Analysis in Infected Patients: 3 Case Reports

Background

Ralstonia mannitolilytica is an emerging opportunistic pathogen. Hospital outbreaks of Ralstonia spp. are mainly associated with contaminated treatment water or auxiliary instruments.

Objectives

In this report, we summarize the clinical infection characteristics of R. mannitolilytica, the drug-susceptibility testing of the bacterial strains, and the results of related infection investigations.

Patients and Methods

We retrospectively analyzed the clinical information of 3 patients with R. mannitolilytica.

Results

The patients’ primary-onset symptoms were chills and fever. The disease progressed rapidly and septic shock symptoms developed. Laboratory tests indicated progressively decreased white blood cells and platelets, as well as significant increases in certain inflammation indicators. The effect of treatment with Tazocin was good. The growth period of R. mannitolilytica in sterile distilled water was > 6 months. The pulsed-field gel electrophoresis (PFGE) results revealed that the infectious strains from these 3 patients were not the same clonal strain. This bacterium was not detected in the nosocomial infection samples.

Conclusions

Our results suggest that R. mannitolilytica-induced septicemia had an acute disease onset and rapid progression. The preferred empirical antibiotic was Tazocin. In these 3 cases, the R. mannitolilytica-induced septicemia was not due to clonal transmission.