Emerging pathogen: a case and review of Raoultella planticola

Clinical Characteristics of Abdominal Infections Caused by Raoultella Spp.: A Retrospective Study

Background: In recent years, Raoultella spp. have attracted clinical attention as a new type of pathogen. The most common of human infection with Raoultella are bacteremia, urinary tract infections, abdominal infections, etc. Abdominal infection is a serious and complex infection problem. However, there have been no systematic reports of abdominal infections caused by Raoultella. The objective of this study was to explore the clinical characteristics of Raoultella abdominal infections and provide a reference for clinical practice. Methods: A review of publications on abdominal infections caused by the genus Raoultella between 2009 and 2024 is carried out. This review studied seven parameters: infection type, number of cases, gender, age, comorbidities, treatment, and outcome, and descriptive statistical methods were used to analyze the results. Results: A total of 40 cases (16 Raoultella ornithinolytica and 24 Raoultella planticola) were analyzed: 20 cases of biliary tract infection, 5 cases of liver infection, and 4 cases of peritonitis. Fever and abdominal pain were the main symptoms, and some patients present with multiple skin flushes, systemic erythema. Of the 40 cases, 92.5% of patients had underlying diseases. Among them, malignant disease, immunodeficiency, and invasive operations increase the risk of infection. On the basis of the drug susceptibility results, the preferred antibiotics are quinolone, third generations of cephalosporins, carbapenems, and aminoglycoside. Last, patients with abdominal infections caused by Raoultella spp. mostly have a good prognosis after early use of sensitive antibiotics. Conclusions: According to existing literature reports, the main type of abdominal infection caused by Raoultella is biliary tract infection, and most patients have other underlying diseases. Malignancy, immune deficiency, and invasive procedures are risk factors for bacterial infections. This review also emphasizes that Raoultella spp. is a rarely found opportunistic pathogen, which can cause a high incidence of healthcare-associated infections after invasive procedures.

Rare Case of Raoultella planticola Infective Endocarditis after Mitral Valve Replacement Surgery

Infective endocarditis remains a condition associated with high morbidity and mortality, regardless of advances in diagnosis and therapeutics. The etiology, microbiology, and epidemiology of infective endocarditis have changed in the last years, with healthcare-associated infective endocarditis being responsible for a myriad of cases. Raoultella planticola is rarely the cause of infective endocarditis. We present a 72-year-old Caucasian female with a history of mitral valve replacement for rheumatic valve disease two months before the current presentation, without any immunosuppressive pathologies, diagnosed with Raoultella planticola infective endocarditis. Long-drawn antibiotic treatment led to a full recovery with no evidence of recurrence or relapse. This report highlights the importance of a multimodal approach for the diagnosis of bacterial etiology, the importance of selection and duration of an appropriate antibiotic regimen, and the presence of a rare opportunistic bacteria that has proven pathogenicity in a wide range of organ systems, usually in patients with several risk factors.

COVID-19 Bullous Lung Disease Superinfection by Raoultella planticola

Bullous lung lesions from coronavirus disease 2019 (COVID-19) pneumonia, causing pneumothorax, are a rare complication, affecting up to 1% of infected patients. Raoultella planticola is an aerobic, gram-negative bacteria known to cause opportunistic infection. We present a rare case of spontaneous pneumothorax from rupture of lung bulla as a late sequela from COVID-19 pneumonia and superinfection of the bulla by R. planticola. Although superinfection of bullous lesions is known, this is the first reported case of R. planticola pneumonia in a patient with COVID-19 lung bullae. COVID-19 patients are at heightened risk for bullous lung lesions and superinfection by opportunistic organisms; thus, they should be followed up closely.

Acute cholecystitis secondary to Raoultella ornithinolytica infection, complicated by sepsis, gallbladder perforation, hepatic abscess and bacteraemia

Herein, a case of an immunocompromised patient in his early 70s is discussed who presented with clinical signs and symptoms compatible with sepsis from an intra-abdominal source and who was found to have blood cultures positive for the encapsulated Gram-negative pathogen Raoultella ornithinolytica, with the source of infection determined, via imaging, to be a case of acute cholecystitis complicated by gallbladder perforation, multiple pericholecystic and hepatic abscesses, and persistent bacteraemia. To our knowledge, this represents the first described case of cholecystitis and gallbladder perforation directly attributed to this species, and highlights both the pathogen's capacity to cause severe disease as well as the utility of a multidisciplinary approach to achieve optimal patient outcome.

Endogenous Ethanol and Triglyceride Production by Gut Pichia kudriavzevii, Candida albicans and Candida glabrata Yeasts in Non-Alcoholic Steatohepatitis

Nonalcoholic steatohepatitis (NASH) increases with fructose consumption and metabolic syndrome and has been recently linked with endogenous ethanol production, notably by high alcohol-producing Klebsiella pneumoniae (HiAlc Kpn). Candida yeasts are the main causes of auto-brewery syndromes but have been neglected in NASH. Here, the fecal ethanol and microbial content of 10 cases and 10 controls were compared. Ethanol was measured by gas chromatography-mass spectrometry. Species identification was performed by MALDI-TOF MS, and triglyceride production was assessed by a colorimetric enzymatic assay. The fecal ethanol concentration was four times higher in patients with NASH (median [interquartile range]: 0.13 [0.05–1.43] vs. 0.034 [0.008–0.57], p = 0.037). Yeasts were isolated from almost all cases but not from controls (9/10 vs. 0/10, p = 0.0001). Pichia kudriavzevii was the most frequent (four patients), while Candida glabrata, Candida albicans, and Galactomyces geotrichum were identified in two cases each. The concentration of ethanol produced by yeasts was 10 times higher than that produced by bacteria (median, 3.36 [0.49–5.60] vs. 0.32 [0.009–0.43], p = 0.0029). Using a 10% D-fructose restricted medium, we showed that NASH-associated yeasts transformed fructose in ethanol. Unexpectedly, yeasts isolated from NASH patients produced a substantial amount of triglycerides. Pichia kudriavzevii strains produced the maximal ethanol and triglyceride levels in vitro. Our preliminary human descriptive and in vitro experimental results suggest that yeasts have been neglected. In addition to K. pneumoniae, gut Pichia and Candida yeasts could be linked with NASH pathophysiology in a species- and strain-specific manner through fructose-dependent endogenous alcohol and triglyceride production.

A Rare Case of Raoultella planticola and Enterococcus casseliflavus Coinfection

Raoultella planticola, a Gram-negative bacterium, is a nonmotile rod usually found in soil and aquatic environments. It can be found in association with gastrointestinal malignancy. Enterococcus casseliflavus is a rare vancomycin-resistant Enterococcus that is responsible for some bacteremia. Our case describes a unique presentation of colonization with both R. planticola and E. casseliflavus isolated from the biliary stent isolates of a patient with known pancreatic malignancy and concomitant E. casseliflavus bacteremia. This is the first case ever reported of infection with both species.

Genetic and virulence characteristics of a Raoultella planticola isolate resistant to carbapenem and tigecycline

Raoultella planticola is an emerging pathogen causing several infections in humans, and its roles in the propagation of antibiotic resistance genes (ARGs) remain uncharacterized. In this study, a carbapenem and tigecycline-resistant R. planticola isolate was recovered from hospital sewage. It carried nine plasmids, bearing 30 ARGs, including one bla_KPC-2 and two bla_NDM-1. It also contained a plasmid-borne efflux pump gene cluster, tmexCD1-toprJ, conferring resistance to tigecycline. Analysis of plasmid sequences revealed that both bla_NDM-1-carrying plasmids were highly similar to those recovered from humans, reinforcing the close relatedness of environmental and clinical isolates. We also identified that plasmid bearing bla_NDM-1 or tmexCD1-toprJ1 was transferable, and can be stabilized in the host bacteria, indicating that the R. planticola isolate has a considerable potential in the dissemination of ARGs. Besides, we found that this isolate could produce biofilm and was virulent in a Galleria mellonella infection model. In conclusion, our study shows the convergence of virulence and multidrug resistance in a R. planticola isolate. This potentially virulent superbug may disseminate into its receiving rivers, and finally to humans through cross-contamination during recreation activities or daily use of water, which poses a risk to public health.

Slow expanders invade by forming dented fronts in microbial colonies

Living organisms never cease to evolve, so there is a significant interest in predicting and controlling evolution in all branches of life sciences. The most basic question is whether a trait should increase or decrease in a given environment. The answer seems to be trivial for traits such as the growth rate in a bioreactor or the expansion rate of a tumor. Yet, it has been suggested that such traits can decrease, rather than increase, during evolution. Here, we report a mutant that outcompeted the ancestor despite having a slower expansion velocity when in isolation. To explain this observation, we developed and validated a theory that describes spatial competition between organisms with different expansion rates and arbitrary competitive interactions.

Most organisms grow in space, whether they are viruses spreading within a host tissue or invasive species colonizing a new continent. Evolution typically selects for higher expansion rates during spatial growth, but it has been suggested that slower expanders can take over under certain conditions. Here, we report an experimental observation of such population dynamics. We demonstrate that mutants that grow slower in isolation nevertheless win in competition, not only when the two types are intermixed, but also when they are spatially segregated into sectors. The latter was thought to be impossible because previous studies focused exclusively on the global competitions mediated by expansion velocities, but overlooked the local competitions at sector boundaries. Local competition, however, can enhance the velocity of either type at the sector boundary and thus alter expansion dynamics. We developed a theory that accounts for both local and global competitions and describes all possible sector shapes. In particular, the theory predicted that a slower on its own, but more competitive, mutant forms a dented V-shaped sector as it takes over the expansion front. Such sectors were indeed observed experimentally, and their shapes matched quantitatively with the theory. In simulations, we further explored several mechanisms that could provide slow expanders with a local competitive advantage and showed that they are all well-described by our theory. Taken together, our results shed light on previously unexplored outcomes of spatial competition and establish a universal framework to understand evolutionary and ecological dynamics in expanding populations.

Raoultella planticola Infection in Urine

Raoultella planticola is a gram-negative, aerobic, nonmotile bacteria that can be found in soil and water. This is a relatively rare organism with few case reports on it and only three reports of R. planticola-induced urinary tract infection (UTI) have been reported. Here we present a case of acute cystitis caused by R. planticola in a woman with atrial fibrillation and recurrent UTIs.

Microbiological and Clinical Aspects of Raoultella spp

The genus Raoultella was established in 2001. Species of Raoultella and Klebsiella share many ecological, biochemical, clinical, and microbiological features. Given the shortcomings of available technology for species identification in the clinical microbiology laboratory, are practically indistinguishable. Since the late 2000s there has been an increase in case reports of human Raoultella infections. Therefore, several authors are postulating that Raoultella spp. are rare and/or emerging pathogens.

Conclusions:Raoultella spp. are very similar to Klebsiella spp. The epidemiology and the clinical relevance of the human Raoultella spp. infections is uncertain and further studies are required. The previous difficulties in the identification of Raoultella spp. and the introduction of more precise identification techniques may explain the recent increase in the number of case reports. Raoultella spp. might be rather underdiagnosed than rare or emerging pathogens.

Complete Genome Sequence of a Canadian Strain of Raoultella planticola with Metal and Antimicrobial Resistance Genes

Raoultella planticola is a Gram-negative opportunistic bacterial pathogen associated with hospital-acquired infections in humans. Here, we report the complete genome sequence of one Raoultella planticola strain isolated from Canadian wastewater treatment facilities containing one chromosome and four plasmids with four antimicrobial resistance (AMR) genes and four metal resistance gene clusters.

Bacteremic cholangitis due to Raoultella planticola complicating intrahepatic bile duct stricture 5 years post-laparoscopic cholecystectomy: a case report

Background

Raoultella Planticola is a facultative anaerobic, gram-negative, water- and soil-dwelling rod bacterium rarely reported as a cause of human disease. However, the number of reported R. planticola infections is growing, without a concomitant increase in research on the microbe or its pathogenesis. Previous genomic studies demonstrating genetic similarities between R. planticola and Klebsiella pneumoniae suggest that capsule biosynthesis, mucoid phenotype, biofilm production, and lipopolysaccharide (endotoxin) synthesis may all be potential virulence factors of R. planticola. We present a unique case of R. planticola infection of the biliary tract 5 years after biliary surgery in a patient with no previously documented risk factors. We also use in silico techniques to predict virulence factors of R. planticola.

Case presentation

This case report is the first to discuss a R. planticola infection in the biliary tract of late onset post-surgery (5 years) in a Caucasian patient with no previously documented risk factors.

Conclusions

An in-depth search of the current literature did not yield other similar cases of R. planticola infections. Moreover, to the best of our knowledge, our case is the first case of R. planticola isolated from post-endoscopic retrograde cholangiopancreatography (ERCP) as part of biliary sepsis not associated with gastroenteritis. The late onset of the infection in our patient and the results of the in silico analysis suggest that R. planticola may have survived exposure to the host immune system through the creation of an intracellular biofilm or in a non-culturable but viable state (NCBV) for the 5-year period. The in silico analysis also suggests that biofilms, enterobactin, and mucoid phenotype may play a role in the pathogenesis of R. planticola. However, further research is needed to illuminate the significance of pili, capsule biosynthesis, and lipopolysaccharide (LPS) in the virulence of R. planticola. Lastly, as our patient did not have any risk factors previously associated with R. planticola, we suggest that biliary tract stricture, cholecystitis, and prior surgery may be possible novel risk factors.

Clinical and microbiological characteristics of patients with Raoultella spp. isolation in Bogotá, Colombia

INTRODUCTION

Raoultella spp. is a gram-negative bacillus with increasing clinical importance due to the development of multi-drug resistance and because it has been reported as a cause of invasive infection. The risk of infection increases if comorbidities present such as diabetes mellitus and malignancies.

METHODS

Descriptive study of clinical and microbiological characteristics in adult patients with Raoultella spp. isolation, treated at a fourth-level hospital in Bogotá, Colombia, between 2015 and 2020.

RESULTS

61 patients with isolation of Raoultella spp., 51 were considered infection and 10, colonization. The associated comorbidities were hypertension (n=26, 42.6%), heart failure (n=19, 31.1%) and diabetes mellitus (n=18, 29.5%). AmpC resistance patterns were found in 10 samples (16.4%) and KPC in 3 (4.9%).

CONCLUSIONS

Raoultella spp. is of clinical importance due to its isolation in immunocompromised patients with multiple comorbidities and due to the increase in multi-resistant strains.

CTX-M-9 group ESBL-producing Raoultella planticola nosocomial infection: first report from sub-Saharan Africa

BACKGROUND

Raoultella are Gram-negative rod-shaped aerobic bacteria which grow in water and soil. They mostly cause nosocomial infections associated with surgical procedures. This case study is the first report of a Raoultella infection in Africa. Case presentation We report a case of a surgical site infection (SSI) caused by Raoultella planticola which developed after caesarean section (CS) and surgery for secondary small bowel obstruction. The patient became febrile with neutrophilia (19,157/µL) 4 days after laparotomy and started to develop clinical signs of a SSI on the 8^th day after laparotomy. The patient continued to be febrile and became critically ill despite empirical treatment with ceftriaxone and vancomycin. Raoultella species with extended antimicrobial resistance (AMR) carrying the CTX-M-9 β-lactamase was isolated from the wound discharge. Considering the antimicrobial susceptibility test, ceftriaxone was replaced by ceftazidime. The patient recovered and could be discharged on day 29 after CS.

CONCLUSIONS

Raoultella planticola was isolated from an infected surgical site after repeated abdominal surgery. Due to the infection the patient's stay in the hospital was prolonged for a total of 4 weeks. It is noted that patients undergoing surgical and prolonged inpatient treatment are at risk for infections caused by Raoultella. The development of a SSI caused by Raoultella planticola with extended AMR has to be assumed to be a consequence of ineffective antibiotic utilization. The presented case advices that rare bacteria as Raoultella should be considered as potential cause of nosocomial SSI with challenging treatment due to high levels of AMR.

A rare case of Bordetella avium pneumonia complicated by Raoultella planticola

Bordetella avium pneumonia immunocompromised the patient with subsequent complication by a rare opportunistic Raoultella planticola infection, which became a nosocomial pathogen in the healthcare setting.

Clinical characteristics and treatment outcomes of patients with pneumonia caused by Raoultella planticola

Background

Raoultella planticola, considered to be an environmental organism, is a rare cause of human infections. Although in recent years the frequency of R. planticola infections reported in the literature has increased, few cases of pneumonia caused by R. planticola have been described. Here, we investigate the clinical characteristics, management, and clinical outcomes of pneumonia caused by R. planticola.

Methods

Consecutive patients with pneumonia caused by R. planticola were included. The medical records of patients with R. planticola pneumonia treated at Dankook University Hospital from January 2011 to December 2017 were collected.

Results

A total of 11 adult patients with R. planticola pneumonia were diagnosed and treated [10 males and 1 female; median age, 70 years (range: 51-79 years)]; 5 patients had underlying malignant conditions (45.5%). Antibacterial susceptibility testing showed that all isolates of R. planticola were susceptible to cephalosporins, carbapenems, fluoroquinolones, aminoglycosides, and beta-lactams/beta-lactamase inhibitors. Chest imaging revealed consolidation (8/11, 72.7%), ground-glass opacity (5/11, 45.5%), pleural effusion (5/11, 45.5%), and micronodules (3/11, 27.3%). Four patients (36.4%) required mechanical ventilation; three survived but one died of multiple organ dysfunction syndrome (principally pneumonia and septic shock).

Conclusions

R. planticola pneumonia occurred mainly in patients with underlying risk factors such as malignant disease, cerebral infarction or hemorrhage, and chronic obstructive pulmonary disease. The organism was sensitive to most antibiotics, and the clinical outcomes were favorable after empirical antibiotic therapy.

Raoultella Bacteremia Presenting as an Acute Self-Limited Illness in an Obstetric Patient

A 20 year-old female at 27-week gestation was admitted for threatened preterm delivery. Following an initially unremarkable hospital course for 12 days, the patient developed fever, chills, generalized malaise, abdominal pain, and diffuse myalgias on day 13 of hospitalization. Raoultella species was isolated from blood cultures on day 16 of hospitalization. The patient's condition improved within 24 hours of symptom onset, prior to antibiotic initiation, and a premature, viable male infant at 29 weeks and 6 days of gestation was delivered via caesarean section four days later due to breech presentation in the setting of preterm labor. Here, we present the first case of a Raoultella species infection in a gravid female reported in the literature.

Maxillary Osteomyelitis with an Incidental Diagnosis of Maxillary Diffuse Large B-Cell Lymphoma: A Case Report

Raoultella planticola osteomyelitis is rarely reported in the literature. The most likely source in our case is the oral microbiome secondary to the tooth extraction. Herein we present a case of Raoultella planticola osteomyelitis of the jaw that leads to the diagnosis of diffuse large B-cell lymphoma (DLBCL) of the jaw. A 75-year-old male with no significant medical history, presented to the emergency department with right upper jaw pain after he had a tooth extraction a week before his presentation. Computed tomography (CT) scan of the face showed concerns of right maxillary osteomyelitis with soft tissue swelling and prominent cervical lymph nodes. He underwent a bone biopsy of the maxilla and was started on intravenous ampicillin-sulbactam. His bone culture grew pan-sensitive Raoultella planticola. in addition to that, his bone biopsy revealed diffuse large B-cell lymphoma of the jaw. The patient underwent staging imaging, and he was found to have metastasis to the liver. He was started on chemotherapy and had a good response. In conclusion, Raoultella planticola osteomyelitis is extremely rare. The diagnosis of maxillary DLBCL can be a challenge. Fortunately, our patient had an infection at the same site that led to the diagnosis of DLBCL.

Histamine-Producing Bacteria and Histamine Induction in Retail Sardine and Mackerel from Fish Markets in Egypt

This study examined the occurrence of histamine-producing bacteria (HPB) and histamine induction in retail sardine and mackerel in Egypt; and whether the fish vendors play a role in the transmission of HPB. Fish were collected from the fish markets, additionally; hand swab samples were taken from the fish vendors. All samples were cultured on modified Niven's medium (MNM); the positive colonies were subcultured on Violet Red Bile Glucose (VRBG) agar, followed by biochemical identification and histidine decarboxylase (hdc)-gene-PCR of the VRBG-positive isolates. The hdc-gene-positive fish and human isolates were subjected to partial hdc-gene-sequencing and phylogenetic analysis. Production of histamine in the fish muscles was measured by high-performance liquid chromatography. A higher percentage of sardine showed the presence of MNM-positive bacteria (84%) than mackerel (53%). Enterobacteriaceae was the dominant family; the most frequent species were Enterobacter cloacae, Raoultella planticola, Citrobacter freundii, and Enterobacter aerogenes. Higher proportion of the R. planticola isolates were hdc positive as compared with the other species. Only 32% sardine and 17% mackerel of the MNM-positive isolates carried the hdc gene. Fish muscles that contain hdc-positive bacteria exhibit higher levels of histamine (median 86; IQR 80-1112 mg/kg) than those with hdc-negative bacteria (48; 75-223 mg/kg). The level of histamine was significantly higher in sardine (109; 104-1094 mg/kg) than in mackerel (40; 49-106 mg/kg). The 20 fish vendor samples were MNM positive, 2 of them were hdc-gene positive. The close genetic relatedness between the human and fish strains isolated from the same markets suggests a possible bidirectional transmission of the HPB. This warns for the presence of HPB carrying hdc gene in retail sardine and mackerel, which is associated with a relatively high level of histamine. Regular inspection of the fish markets is required, including accurate determination of HPB by using a combination of the MNM culture, hdc-gene PCR, and measurement of histamine level.

A Rare Case of Raoultella planticola Urinary Tract Infection in a Patient With Immunoglobulin A Nephropathy

Raoultella planticola is a gram-negative, aerobic, nonmotile mostly found in environments with high prevalence in soil and water. This organism is a very rare human pathogen as only 29 cases of Raoultella planticola–related infections have been reported until 2017, with only 7 cases in the United States. Only 3 cases of urinary tract infection secondary to R planticola have been reported, 1 in a pediatric patient and 2 in adults. In this article, we present a case of R planticola urinary tract infection in a 65-year-old male with immunoglobulin A nephropathy. On investigation, the patient was found to be septic and empirical antibiotic was started for gram-negative coverage. The patient showed remarkable improvement and discharged on oral antibiotic for 7 days. R planticola rarely cause infection in humans, with overall good prognosis.

Raoultella planticola Bacteremia in a Patient with Early Gastric Cancer

The patient was an 81-year-old man who was found to have bacteremia due to Raoultella planticola, which might have entered the circulation through the bile duct during the passing of a gallbladder stone. In the present case, we screened for malignancies because most cases of R. planticola bacteremia occur after trauma, invasive procedures, or in patients with malignancy (70.6%). Early gastric cancer was detected. Although the association between R. planticola bacteremia and malignancy remains speculative in the present case, it may be useful to scrutinize similar cases involving low-virulence bacteremia for possible malignancies or immune conditions.

Community-acquired infection to Raoultella ornithinolytica presenting as appendicitis and shock in a healthy individual

Raoultella ornithinolytica and Raoultella planticola are histamine-producing bacteria that are usually found in fish and water. They are associated with scombroid syndrome that presents with vomiting and flushing. A wide range of infections with these germs is reported, but mainly in fragile hospitalized patients with multiple comorbidities. We report the case of a 54-year-old healthy patient who presented with 24-hours abdominal pain, vomiting, flushing and shock. The abdominal examination showed guarding in the right lower quadrant (RLQ), and the abdominal CT scan images showed a thickened terminal ileum and a distended appendix. The patient underwent a surgical exploration revealing a normal terminal ileum but an inflamed appendicular base. Raoultella ornithinolytica was found in blood cultures and in the liquid retrieved from the RLQ. To the best of our knowledge, this is the first report of a severe life-threatening intra-abdominal presentation due to a community-acquired R. ornithinolytica infection.

Raoultella planticola bacteremia-induced fatal septic shock following burn injury

BACKGROUND

Raoultella planticola, a Gram-negative, aerobic bacillus commonly isolated from soil and water, rarely causes invasive infections in humans. Septic shock from R. planticola after burn injury has not been previously reported.

CASE PRESENTATION

A 79-year-old male was admitted to the emergency intensive care unit after extensive flame burn injury. He accidently caught fire while burning trash and plunged into a nearby tank filled with contaminated rainwater to extinguish the fire. The patient developed septic shock on day 10. The blood culture detected R. planticola, which was identified using the VITEK-2 biochemical identification system. Although appropriate antibiotic treatment was continued, the patient died on day 12.

CONCLUSIONS

Clinicians should be aware of fatal infections in patients with burn injury complicated by exposure to contaminated water.

The first case of Raoultella planticola infective endocarditis in a 4 year old child: A case report and review of literature

Infective endocarditis is a complication of bacteremia that can lead to serious morbidity and even mortality if not appropriately treated, well known organisms commonly lead to this condition in many repeated scenarios so they are usually recognized and treated, but if it was caused by other organisms its detection and treatment can be harder. Raoultella planticola, a low virulent organism used to be part of the Klebsiella species, has been found in many reports to cause multiple human conditions. In this article, a novel case of R. planticola is reported, and the organism was reviewed in many aspects for clinician to be able to recognize this infection and manage it in a more effective way.

Mandibular osteomyelitis due to Raoultella species

Introduction

Raoultella is a genus of aerobic Gram-negative bacilli belonging to the family Enterobacteriaceae that are commonly found in water, soil and aquatic environments. With improved bacterial identification techniques, Raoultella species (namely R. planticola and R. ornithinolytica) have been an increasingly reported cause of infections in humans.

Case presentation

An 85-year-old man presented to hospital with a several-week history of left jaw pain and trismus. His medical history was significant for left mandibular osteomyelitis treated 1 year previously with amoxicillin-clavulanate. On admission, a computed tomography scan demonstrated a 2.6×1.7×1.6 cm peripherally enhancing collection surrounding the left posterior mandibular body. Two aspirates of the abscess grew a bacterium belonging to the genus Raoultella, with discordant species identification (R. ornithinolytica versus R. planticola) using two different techniques. A potential source of infection included a left lower molar tooth which was extracted months preceding the original diagnosis of osteomyelitis.

Conclusion

This is the first case of mandibular osteomyelitis caused by Raoultella species reported in the literature. In contrast to other forms of osteomyelitis, the pathogenesis of mandibular osteomyelitis involves contiguous spread from an odontogenic focus. Risk factors for mandibular osteomyelitis include a history of fracture, irradiation, diabetes and steroid therapy. This report adds to the growing literature of infections caused by this genus of bacteria, and raises the possibility of this organism’s role in odontogenic infections.

Is It Necessary to Specifically Define the Cause of Surgically Treated Biliary Tract Infections? A Rare Case of Raoultella planticola Cholecystitis and Literature Review

Raoultella planticola is an aquatic and soil organism that does not notoriously cause invasive infections in humans. Infections in the literature are limited only in case reports. We present a very rare case of R. planticola cholecystitis. A 71-year-old female patient with abdominal pain was diagnosed with acute cholecystitis. Patient received intravenous antibiotic treatment, but the treatment failed and the patient underwent an open cholecystectomy. The final pathological result was gangrenous cholecystitis complicated with R. planticola. Eventually, the patient recovered with appropriate antimicrobial therapy. Patients with acute cholecystitis are usually treated without any microbiological sampling and antibiotic treatment is started empirically. To date, there have only been 5 reported biliary system related R. planticola infections in humans. We believe that Raoultella species might be a more frequent agent than usually thought, especially in resistant cholecystitis cases. Resistant strains should be considered as a possible causative organism when the patient’s condition worsened despite proper antimicrobial therapy. It should be considered safe to send microbiological samples for culture and specifically define the causative microorganisms even in the setting of a cholecystectomized patient.

A new emerging oral infection: Raoultella planticola in a boy with haematological malignancy

BACKGROUND

Oral mucositis is a common complication in pediatric cancer patients, affecting up to 80% of children. Due to neutropenia and disruption of the mucosal barrier, chemotherapy-induced oral mucositis is often complicated by super-infections.

CASE REPORT

A 16-years old male with stage 3 Burkitt's lymphoma developed chemotherapy induced oral mucositis grade 3 (according to WHO scale). Ulcers were quickly growing (reaching a maximum diameter of 3 cm) and became greyish in colour, resulting in dysphagia and pain. A swab of the lesions was taken and microbiological tests were performed. The sample grew for Raoultella planticola, an encapsulated Gram-negative bacterium whose full pathogenic potential still needs to be defined.

TREATMENT

The patient received antibiotic combination therapy with Amikacin and Ceftazidime for 8 days. Complete healing of the lesions and resolution of the symptoms were reached and he completed his antineoplastic therapy without further complications.

FOLLOW-UP

Twelve months after the infection, he is alive and well, with no oral complaints.

CONCLUSION

This is the first report of a Raoultella planticola infection in a patient with chemotherapy induced oral mucositis. This type of infection must be added to the list of organisms to be considered when caring for these patients.

Joint infection due to Raoultella planticola: first report

The genus Raoultella has been separated from the genus Klebsiella in 2001. Two main species are responsible for human infections: R. ornithinolytica and R. planticola. The most frequent infections due to R. planticola include cystitis, pneumonia and bacteremia (mostly in immunocompromised hosts). To date, no joint or bone infection has been reported. We describe the first case of septic arthritis due to R. planticola following an arthroscopy with intra-articular injection of corticosteroids. Evolution was favorable after arthroscopic lavage and antibiotic therapy with quinolones. Raoultella planticola has been described rarely in human infection. It is mainly deemed responsible for cystitis, pneumonia and bacteremia (mostly in immunocompromised hosts) [1-3]. To our knowledge no case of bone or joint infection has been reported. We described here the first case of infective arthritis due to R. planticola involving a native knee joint following synovectomy and intra-articular injection of corticosteroids during arthroscopy.

A rare case of Raoultella planticola urinary tract infection in an immunocompromised patient with multiple myeloma

INTRODUCTION

Raoultella planticola is a gram-negative rod associated with soil and aquatic environments that has rarely been associated with human infections.

PRESENTATION OF CASE

We present the case of a 73 year old female with multiple myeloma and recurrent Clostridium difficile infection who was found to have a urinary tract infection with Raoultella planticola, which has only been reported to cause 29 cases of human infections and 2 cases of urinary tract infections.

DISCUSSION AND CONCLUSION

Our case and literature review suggest that immunocompromised patients are predisposed to developing Raoultella planticola infection, and that this is a potential emerging pathogen.

Raoultella spp.-clinical significance, infections and susceptibility to antibiotics

The genus Raoultella belongs to the family of Enterobacteriaceae. Raoultella spp. are Gram-negative, aerobic, non-motile rods. This genus can be distinguished from the genus Klebsiella, in that genus use histamine as the only source of carbon in the medium. Also, Raoultella grow at 4 °C and do not produce gas from lactose at 44.5 °C. Raoultella sp. is known to inhabit natural environments (water, soil, plants). The reservoir of Raoultella is the gastrointestinal tract and upper respiratory tract. Raoultella spp. are opportunistic bacteria, which usually cause infections of the biliary tract, pneumonia and bacteraemia in oncologic and with lower immunity patients. Raoultella planticola and Raoultella ornithinolytica are the most frequently encountered human pathogens among the genus Raoultella. In this review, the current knowledge on Raoultella infections is summarized.

Combination of Tigecycline and Levofloxacin for Successful Treatment of Nosocomial Pneumonia Caused by New Delhi Metallo-β-Lactamase-1-Producing Raoultella planticola

Raoultella planticola is a gram-negative bacterium that rarely causes diseases in humans. Here, we present a case of hospital-acquired pneumonia caused by R. planticola that likely originated in the gastrointestinal tract. To the best of our knowledge, this is the second report describing the detection of the gene New Delhi Metallo-β-lactamase-1 (bla_NDM-1) in multidrug-resistant R. planticola. Clinical samples were collected for bacterial culture and antimicrobial susceptibility testing from a patient during hospitalization. The presence of bla_NDM-1 was detected by PCR and sequencing. An NDM-1-positive R. planticola was isolated from the sputum and stool of the same patient. Further findings confirmed that bla_NDM-1 was located on a plasmid. Isolates from the sputum and stool cultures were identical, suggesting that the R. planticola may have originated in the gastrointestinal tract. The patient completely recovered and was discharged after treatment with tigecycline combined with levofloxacin, for a week. In conclusion, R. planticola is a possibly underestimated pathogen that contributes to the spread of the bla_NDM-1 gene. Early and precise identification of this pathogen can lead to better prognosis of the associated infections and an improved approach to controlling the spread of carbapenemase-resistant gram-negative bacteria.

Fatal pancreatic pseudocyst co-infected by Raoultella planticola: an emerging pathogen

Raoultella planticola is an aerobic Gram-negative bacterium belonging to the Enterobacteriaceae family. Initially identified in the 1980s, its pathogenic potential was further recognized when the first case of bacteremia was reported. Since then, only a few infections caused by this pathogen have been described. Although considered an opportunistic agent, fatal outcomes are associated with the infection by this pathogen, since it is more prevalent among the patients with immunodeficiency. The authors report the case of a middle-aged man diagnosed with end-stage renal disease and alcoholic pancreatitis, who was admitted to the emergency department with septic shock. Physical examination disclosed peritoneal irritation and a laparotomy was undertaken. Purulent peritonitis was found as well as a retroperitoneal abscess, which was drained. The postoperative period was troublesome, and the patient died. The autopsy showed a ruptured, infected pancreatic cyst and purulent peritonitis, among other findings. The culture of the peritoneal fluid and two blood sample sets were positive for R. planticola. The authors call attention to the importance of this emerging pathogen associated with severe gastrointestinal infections.

Comparison of different methods for identification of species of the genus Raoultella: report of 11 cases of Raoultella causing bacteraemia and literature review

The genus Raoultella was excised from Klebsiella in 2001, but difficulties in its identification may have led to an underestimation of its incidence and uncertainty on its pathogenic role. Recently, clinical reports involving Raoultella have increased, probably through the introduction of mass-spectrometry in clinical microbiology laboratories and the development of accurate molecular techniques. We performed a retrospective analysis using our blood culture collection (2011-14) to identify Raoultella isolates that could have been erroneously reported as Klebsiella. PCR and gene sequencing of highly specific chromosomal class A β-lactamase genes was established as the reference method, and compared with 16S rRNA and rpoβ sequencing, as well as matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF MS), MicroScan Walkaway system and API20E biochemical identification. MALDI-TOF and rpoβ correctly identified all Raoultella isolates, whereas 16S rRNA provided inconclusive results, and MicroScan and API20E failed to detect this genus. The analysis of the clinical characteristics of all Raoultella bacteraemia cases reported in the literature supports the role of Raoultella as an opportunistic pathogen that causes biliary tract infections in elderly patients who suffer from some kind of malignancy or have undergone an invasive procedure. Two salient conclusions are that Raoultella shows tropism for the biliary tract and so its identification could help clinicians to suspect underlying biliary tract disease when bacteraemia occurs. Concomitantly, as most phenotypic identification systems are not optimized for the identification of Raoultella, the use of MALDI-TOF or additional phenotypic tests is recommended for the reliable identification of this genus.

Acute Raoultella planticola cystitis in a child with rhabdomyosarcoma of the bladder neck

Raoultella planticola is a Gram-negative, non-motile, aerobic bacillus. It is an environmental bacteria found in soil and water, and a very rare cause of local or systemic infection in humans. Although some adult cases of R. planticola infection have been reported, childhood local or systemic infection caused by R. planticola is very rare. Reported herein is a rare case of acute cystitis due to R. planticola in a 16-month-old boy with rhabdomyosarcoma of the bladder neck, and a review of the literature.

Infections on the rise: Raoultella spp., clinical and microbiological findings from a retrospective study, 2010-2014

We performed a retrospective analysis of clinical and laboratory data over 5 years in a tertiary centre to assess clinical and microbiological characteristics of patients with Raoultella spp. infection. Raoultella spp. were deemed responsible for clinical infections in 57 patients (R. planticola, n = 32 and R. ornithinolytica, n = 25). The most prevalent diagnoses for R. planticola were cystitis (50%; n = 16) followed by bacteraemia and pneumonia (9.4%; n = 3); for R. ornithinolytica, cystitis (36%; n = 9) followed by pneumonia (24%; n = 6). Immunodeficiency was present in 18 patients (56.3%) with R. planticola and in 16 patients (64%) with R. ornithinolytica infection. Of these, 55.6% and 37.5% had diabetes and 27.8% and 18.% were solid organ transplant recipients, respectively. All isolates were sensitive to third-generation cephalosporins, fluoroquinolones and aminoglycosides. Mortality of infections with R. planticola (n = 5; 15.6%) was higher than for R. ornithinolytica (n = 2; 8.0%), but the difference was not statistically significant.

Raoultella planticola peritonitis in a patient on continuous ambulatory peritoneal dialysis

A 65-year-old man on continuous ambulatory peritoneal dialysis was admitted with peritonitis. Empirical antibiotic therapy was initiated, and Raoultella planticola was identified in the peritoneal fluid culture. We treated the patient with intraperitoneally administered ciprofloxacin and ceftazidime according to the antibiotic susceptibility. His condition improved, and he was well treated with a 2-week antibiotic course.

Nosocomial pneumonia caused by carbapenem-resistant Raoultella planticola: a case report and literature review

Raoultella planticola is a rare opportunistic pathogen usually invaded immunocompromised patients and sometimes even causes fatal infections. Recently, there is growing concern about the emergence of carbapenem resistance in this species. Here, we describe one case of hospital-acquired pneumonia due to a carbapenem-resistant R. planticola (CRRP) co-producing Klebsiella pneumoniae carbapenemase and extended-spectrum β-lactamase. A literature review was performed to indicate the microbiological and clinical features of infections caused by CRRP.

Clinical characteristics of Raoultella ornithinolytica bacteremia

PURPOSE

Raoultella ornithinolytica is not well known as a clinical pathogen. We performed a retrospective review of R. ornithinolytica bacteremia to investigate its clinical features, antimicrobial susceptibility, and overall patient outcomes.

METHODS

R. ornithinolytica bacteremia cases were collected from an electronic database of all cases of bacteremia over a 10-year period. Medical records were retrospectively reviewed. Demographic data, clinical information, the presence of underlying comorbidities, the results of antimicrobial susceptibility testing, and the antimicrobial regimen administered were investigated.

RESULTS

R. ornithinolytica was isolated from blood culture specimens in 16 cases. The majority of these patients had an underlying malignant condition of advanced stage (15 patients, 94 %). Seven of these patients had a solid tumor with lesions or metastases that extended to the bile duct or biliary tract. Neutropenic fever following hematologic stem cell transplantation was found in three cases. No resistance to piperacillin/tazobactam or imipenem was found. Four cases showed resistance to cefoxitin, while one of these cases showed resistance to multiple cephalosporins. In overall outcomes, seven patients (44 %) did not recover from the infection and subsequently expired.

CONCLUSIONS

R. ornithinolytica bacteremia occurs mainly in patients with underlying malignancies. The overall outcome was not favorable, despite favorable antimicrobial susceptibility test results. The findings of this study contradict those of other studies that demonstrated that infection from Raoultella species have good prognoses.