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Purpose: Raoultella spp. is a genus of bacteria that is known to be closely related to Klebsiella. It has been debated whether Raoultella should be reclassified as a subgroup of Klebsiella. The aim of this study is to compare clinical aspects of Raoultella and Klebsiella oxytoca, a species of Klebsiella that is known to be bacteriologically similar to Raoultella spp. Methods: Using data collected at a tertiary care hospital in the United States, we identified 43 patients with Raoultella infection and 1173 patients with Klebsiella oxytoca infection. We compared patient demographics (age and sex), hospitalization status, isolation sites and antibiotic resistance profiles between the two species. Results: There was no significant difference in patient demographics between the two bacteria species. The proportions of intensive care unit (ICU) admission were higher among patients with Raoultella infection (p=0.008). The most common site of isolation was urine for both species (39.5% of all patients with Raoultella spp. vs. 59.3% for K. oxytoca). The second most common site of isolation was blood stream for Raoultella spp. (23.3%) and respiratory tract for K. oxytoca (10.8%). Except for the high proportion of resistant isolates of Raoultella spp. for Trimethoprim/sulfamethoxazole, the antibiotic susceptibility profiles were similar between the two bacteria species. Both were susceptible to ciprofloxacin and meropenem. Conclusion: While there are no significant differences in the patient demographics and antibiotic susceptibility profiles between Raoultella spp. and K. oxytoca, Raoultella may cause more serious infection requiring ICU admissions. Also, Raoultella may cause blood stream infection more frequently than K. oxytoca. [ABSTRACT FROM AUTHOR]

Seventeen Gram-negative, facultatively anaerobic bacterial strains were isolated from bleeding cankers of various broadleaf hosts and oak rhizosphere soil in Great Britain. The strains were tentatively identified as belonging to the genus Raoultella based on 16S rRNA gene sequencing. Multilocus sequence analysis (MLSA), based on four protein-encoding genes (fusA, leuS, pyrG, and rpoB), separated the strains into three clusters within the Raoultella genus clade. The majority of strains clustered with the type strain of Raoultella terrigena, with the remaining strains divided into two clusters with no known type strain. Whole genome sequencing comparisons confirmed these two clusters of strains as belonging to two novel Raoultella species which can be differentiated phenotypically from their current closest phylogenetic relatives. Therefore, two novel species are proposed: Raoultella scottia sp. nov. (type strain = BAC 10a-01-01T = LMG 33072T = CCUG 77096T) and Raoultella lignicola sp. nov. (type strain = TW_WC1a.1T = LMG 33073T = CCUG 77094T). [ABSTRACT FROM AUTHOR]

PurposeRaoultella spp. is a genus of bacteria that is known to be closely related to Klebsiella. It has been debated whether Raoultella should be reclassified as a subgroup of Klebsiella. The aim of this study is to compare clinical aspects of Raoultella and Klebsiella oxytoca, a species of Klebsiella that is known to be bacteriologically similar to Raoultella spp.MethodsUsing data collected at a tertiary care hospital in the United States, we identified 43 patients with Raoultella infection and 1173 patients with Klebsiella oxytoca infection. We compared patient demographics (age and sex), hospitalization status, isolation sites and antibiotic resistance profiles between the two species.ResultsThere was no significant difference in patient demographics between the two bacteria species. The proportions of intensive care unit (ICU) admission were higher among patients with Raoultella infection (p=0.008). The most common site of isolation was urine for both species (39.5% of all patients with Raoultella spp. vs. 59.3% for K. oxytoca). The second most common site of isolation was blood stream for Raoultella spp. (23.3%) and respiratory tract for K. oxytoca (10.8%). Except for the high proportion of resistant isolates of Raoultella spp. for Trimethoprim/sulfamethoxazole, the antibiotic susceptibility profiles were similar between the two bacteria species. Both were susceptible to ciprofloxacin and meropenem.ConclusionWhile there are no significant differences in the patient demographics and antibiotic susceptibility profiles between Raoultella spp. and K. oxytoca, Raoultella may cause more serious infection requiring ICU admissions. Also, Raoultella may cause blood stream infection more frequently than K. oxytoca.

Seventeen Gram-negative, facultatively anaerobic bacterial strains were isolated from bleeding cankers of various broadleaf hosts and oak rhizosphere soil in Great Britain. The strains were tentatively identified as belonging to the genus Raoultella based on 16S rRNA gene sequencing. Multilocus sequence analysis (MLSA), based on four protein-encoding genes (fusA, leuS, pyrG, and rpoB), separated the strains into three clusters within the Raoultella genus clade. The majority of strains clustered with the type strain of Raoultella terrigena, with the remaining strains divided into two clusters with no known type strain. Whole genome sequencing comparisons confirmed these two clusters of strains as belonging to two novel Raoultella species which can be differentiated phenotypically from their current closest phylogenetic relatives. Therefore, two novel species are proposed: Raoultella scottia sp. nov. (type strain = BAC 10a-01-01T = LMG 33072T = CCUG 77096T) and Raoultella lignicola sp. nov. (type strain = TW_WC1a.1T = LMG 33073T = CCUG 77094T).

This study aims to report an acute dacryocystitis associated with Raoultella planticola infection. The patient's medical records and laboratory were thoroughly assessed. A thorough literature search was performed in PubMed database. An additional search was made in Google Scholar to complete the collected items. This is the first recorded case of acute dacryocystitis attributed to Raoultella planticola infection. A limited number of studies has related this pathogen with conjunctivitis. Acute dacryocystitis on rare occasions can also be caused by atypical organisms. Swabs must be obtained and patients must be started on empirical treatment while waiting for the laboratory results. [ABSTRACT FROM AUTHOR]

Simple Summary: Nitrogen is a vital element that all living organisms require for growth and development. Although the atmosphere has an abundant supply of gaseous nitrogen, unfortunately, most organisms are unable to utilize it. Some microorganisms are capable of converting nitrogen gas to ammonia, which serves as a nitrogen source available to most organisms. Ammonia is subsequently utilized by organisms to synthesize a range of nitrogen-containing compounds that are necessary for life activities. For example, nitrogen-fixing microorganisms aid leguminous plants in obtaining the required nitrogen. Herbivorous insects face significant growth and development restrictions due to low total nitrogen content in their food. In this study, we isolated a nitrogen-fixing bacterium, Raoultella electrica, from the digestive tract of the leafhopper, Recilia dorsalis. R. electrica has all the nitrogen fixation genes and colonizes the gut lumen of leafhoppers. We further evaluated the growth rate of R. electrica in nitrogen-containing and nitrogen-free media and measured its nitrogenase activity through an acetylene reduction assay. These findings may be useful in studying the biological nitrogen fixation by gut microbes in host insects. Nitrogen is a crucial element for the growth and development of insects, but herbivorous insects often suffer from nitrogen nutrition deficiencies in their diets. Some symbiotic microorganisms can provide insect hosts with nitrogen nutrition through nitrogen fixation. Extensive research has clearly demonstrated the process of nitrogen fixation by symbiotic microorganisms in termites, while evidence supporting the occurrence and significance of nitrogen fixation in the diets of the Hemiptera is less conclusive. In this study, we isolated a strain of R. electrica from the digestive tract of a leafhopper, R. dorsalis, and found that it had nitrogen-fixing capabilities. Fluorescence in situ hybridization results showed that it was located in the gut of the leafhopper. Genome sequencing revealed that R. electrica possessed all the genes required for nitrogen fixation. We further evaluated the growth rate of R. electrica in nitrogen-containing and nitrogen-free media and measured its nitrogenase activity through an acetylene reduction assay. The findings of these studies could shed light on how gut microbes contribute to our understanding of nitrogen fixation. [ABSTRACT FROM AUTHOR]

Sai Vikram Alampoondi Venkataramanan, Lovin George, Kamal Kant Sahu, George M Abraham Department of Medicine, Saint Vincent Hospital, Worcester, MA, 01608, USACorrespondence: Kamal Kant SahuDepartment of Medicine, Saint Vincent Hospital, Worcester, MA, 01608, USAEmail drkksahu85@gmail.comIntroduction: Raoultella planticola is an aerobic gram-negative rod predominantly found in soil and aquatic environments. The typical reservoirs of Raoultella spp. include the gastrointestinal tract and the upper respiratory tract. It usually causes pneumonia, biliary tract infections, and bacteremia. Urinary tract infection (UTI) secondary to R. planticola is an uncommon entity. Less than 10 cases of R. planticola-associated UTIs in adults have been published in the literature to date.Objective: This is a single institution retrospective study undertaken to identify the epidemiology, patient characteristics, clinical spectrum, predisposing risk factors and the outcome of patients with UTI caused by R. planticola.Results: A total of 37 R. planticola isolates were identified in urine samples over a 5-year study period. The mean age of the patient population was 77 years. The most common comorbidity was diabetes mellitus, which was present in 16 patients. Only 3 patients had a history of steroid use, an immunosuppressive condition, or were on chemotherapy. The most common presenting complaint was altered mental status followed by fever. Resistance to ampicillin was found in 35 isolates which seems to be an intrinsic characteristic of Raoultella spp. and 2 isolates were multidrug-resistant, but still susceptible to ciprofloxacin. The average length of stay was 3 days, and the average duration of antibiotic administration was 8 days. Ciprofloxacin was the most frequently prescribed antibiotic (9 patients). The severity of infection ranged from simple cystitis in 15 patients to urosepsis in 2 patients and septic shock in 2 patients. There were no mortalities in our cohort.Conclusion: Our study revealed that patients with R. planticola UTI had higher proportion of diabetes mellitus, renal failure compared to the general population. Our study also confirms the intrinsic resistance to ampicillin of Raoultella spp., which has been documented previously in the literature.Keywords: infection, antibiotics, Raoultella, urinary tract infection, bacteriuria

Nitrogen is a crucial element for the growth and development of insects, but herbivorous insects often suffer from nitrogen nutrition deficiencies in their diets. Some symbiotic microorganisms can provide insect hosts with nitrogen nutrition through nitrogen fixation. Extensive research has clearly demonstrated the process of nitrogen fixation by symbiotic microorganisms in termites, while evidence supporting the occurrence and significance of nitrogen fixation in the diets of the Hemiptera is less conclusive. In this study, we isolated a strain of R. electrica from the digestive tract of a leafhopper, R. dorsalis, and found that it had nitrogen-fixing capabilities. Fluorescence in situ hybridization results showed that it was located in the gut of the leafhopper. Genome sequencing revealed that R. electrica possessed all the genes required for nitrogen fixation. We further evaluated the growth rate of R. electrica in nitrogen-containing and nitrogen-free media and measured its nitrogenase activity through an acetylene reduction assay. The findings of these studies could shed light on how gut microbes contribute to our understanding of nitrogen fixation.

The genus Raoultella contains Raoultella ornithinolytica (R. ornithinolytica), which was previously named as Klebsiella ornithinolytica. R. ornithinolytica is a Gram-negative bacillus that belongs to the family Enterobacteriaceae. This pathogen is normally present in aquaculture, and it has been isolated from fish, insects, and wild and domestic birds. Seafood and poultry products are incriminated as sources of R. ornithinolytica infection. Community-acquired human infection with R. ornithinolytica is common. This infection is commonly associated with sepsis, bacteremia, food poisoning, purities, and urinary and respiratory tracts' infections. Rapid acquired resistance of R. ornithinolytica strains is common, and it is related to the development of resistant genes. R. ornithinolytica is considered as a newly emerging life-threatening pathogen world-wide. Hence, it is very important to determine the role of animals and birds in the epidemiological situation of this pathogen as well as the detection of antibiotic resistance genes before treatment.

This study deals with 16S-rDNA identified bacteria, Lysinibacillus sp., Raoultella sp., and Streptomyces sp. capable of precipitating CaCO3 through nitrate reduction aerobically and anaerobically. The produced CaCO3 crystals were analyzed using XRD, EDX, FTIR, TGA and SEM. The results showed that the carbonatogenic bacteria served as nucleation sites for CaCO3 precipitation with distinct variation in polymorph and morphology; reflecting strain-specific property. Notably, the amount of precipitated CaCO3 recorded 3.27 (aerobic), 1.55 (anaerobic), 4.15 (aerobic), 3.75 (aerobic) and 1.87 (anaerobic) g/100 mL of strains Lysinibacillus sp., Streptomyces sp. and Raoultella sp., respectively, after 240 h of incubation. The study of changes in media chemistry during carbonatogenesis process revealed positive correlation between bacterial growth, nitrate reductase activity, pH, EC, Ca2+ depletion, amount of deposited CaCO3 and NO3− consumption. Therefore, the applications of these bacterial strains, which were employed for the first time in carbonatogenesis process, are promising in the environmental, biomedical and civil engineering fields. [ABSTRACT FROM AUTHOR]

Abstract Background l-Fucose is a rare sugar with potential uses in the pharmaceutical, cosmetic, and food industries. The enzymatic approach using l-fucose isomerase, which interconverts l-fucose and l-fuculose, can be an efficient way of producing l-fucose for industrial applications. Here, we performed biochemical and structural analyses of l-fucose isomerase identified from a novel species of Raoultella (RdFucI). Results RdFucI exhibited higher enzymatic activity for l-fuculose than for l-fucose, and the rate for the reverse reaction of converting l-fuculose to l-fucose was higher than that for the forward reaction of converting l-fucose to l-fuculose. In the equilibrium mixture, a much higher proportion of l-fucose (~ ninefold) was achieved at 30 °C and pH 7, indicating that the enzyme-catalyzed reaction favors the formation of l-fucose from l-fuculose. When biochemical analysis was conducted using l-fuculose as the substrate, the optimal conditions for RdFucI activity were determined to be 40 °C and pH 10. However, the equilibrium composition was not affected by reaction temperature in the range of 30 to 50 °C. Furthermore, RdFucI was found to be a metalloenzyme requiring Mn2+ as a cofactor. The comparative crystal structural analysis of RdFucI revealed the distinct conformation of α7–α8 loop of RdFucI. The loop is present at the entry of the substrate binding pocket and may affect the catalytic activity. Conclusions RdFucI-catalyzed isomerization favored the reaction from l-fuculose to l-fucose. The biochemical and structural data of RdFucI will be helpful for the better understanding of the molecular mechanism of l-FucIs and the industrial production of l-fucose.

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Introduction: Raoultella planticola is an aerobic gram-negative rod predominantly found in soil and aquatic environments. The typical reservoirs of Raoultella spp. include the gastrointestinal tract and the upper respiratory tract. It usually causes pneumonia, biliary tract infections, and bacteremia. Urinary tract infection (UTI) secondary to R. planticola is an uncommon entity. Less than 10 cases of R. planticola-associated UTIs in adults have been published in the literature to date. Objective: This is a single institution retrospective study undertaken to identify the epidemiology, patient characteristics, clinical spectrum, predisposing risk factors and the outcome of patients with UTI caused by R. planticola. Results: A total of 37 R. planticola isolates were identified in urine samples over a 5-year study period. The mean age of the patient population was 77 years. The most common comorbidity was diabetes mellitus, which was present in 16 patients. Only 3 patients had a history of steroid use, an immunosuppressive condition, or were on chemotherapy. The most common presenting complaint was altered mental status followed by fever. Resistance to ampicillin was found in 35 isolates which seems to be an intrinsic characteristic of Raoultella spp. and 2 isolates were multidrug-resistant, but still susceptible to ciprofloxacin. The average length of stay was 3 days, and the average duration of antibiotic administration was 8 days. Ciprofloxacin was the most frequently prescribed antibiotic (9 patients). The severity of infection ranged from simple cystitis in 15 patients to urosepsis in 2 patients and septic shock in 2 patients. There were no mortalities in our cohort. Conclusion: Our study revealed that patients with R. planticola UTI had higher proportion of diabetes mellitus, renal failure compared to the general population. Our study also confirms the intrinsic resistance to ampicillin of Raoultella spp., which has been documented previously in the literature. [ABSTRACT FROM AUTHOR]

Background: There have been few clinical studies of Raoultella infections but Raoultella is potentially virulent and multidrug resistant. The aims of the study were to compare the clinical characteristics and outcomes of patients with Raoultella and Klebsiella pneumoniae bloodstream infections (BSIs). Methods: We retrospectively reviewed the records of patients with Raoultella and K. pneumoniae BSIs admitted to a tertiary hospital between 2008 and 2017. Results: A total of 37 cases of Raoultella BSIs were identified and matched to 160 cases of K. pneumoniae BSIs by age and sex using propensity score matching. Patients with Raoultella BSIs were more likely to have underlying biliary tract disease (54.1% versus 24.4%; p <.001) and have a community-acquired infection (62.2% versus 43.1%; p =.04) than those with K. pneumoniae BSIs. Intra-abdominal infection was the most common primary focus of infection. Biliary tract infection (64.9% versus 38.8%; p =.004) and pancreatitis (13.5% versus 3.8%; p =.03) were more common in patients with Raoultella BSIs. Raoultella isolates exhibited significantly higher susceptibility to aztreonam, cefepime, and cefotaxime. The 14-day and 30-day mortality rates were lower among the patients with Raoultella BSIs but did not differ significantly between groups (11% versus 22%; p =.16 and 11% versus 26%; p =.08 for Raoultella and K. pneumoniae BSIs, respectively). Conclusion:Raoultella spp. BSI more likely to occur in patients with underlying biliary tract disease and in community settings compared with K. pneumoniae BSIs. Biliary tract infection was the most common primary focus of Raoultella BSIs. [ABSTRACT FROM AUTHOR]

Klebsiella spp. are important opportunistic pathogens commonly defined as environmental clinical mastitis agents. Despite Klebsiella mastitis being clinically impairing in cows and costly to the industry, only a few studies describe Klebsiella isolated from mastitis cases. The aim of this work was to characterize species of Klebsiella involved in clinical mastitis cases in Canada. Klebsiella isolated from clinical mastitis cases (n = 53) were identified to the species level using a biochemical test panel and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The rpoB gene sequence was used as the gold standard method and identified Klebsiella pneumoniae (n = 40), Klebsiella oxytoca (n = 9), Raoultella ornithinolytica (n = 2), and Raoultella planticola (n = 2). Raoultella , a genus closely related to Klebsiella, was also accurately identified using mass spectrometry but not via biochemical testing. Using the disc diffusion technique, 31 (58%) isolates were found to be susceptible to all antimicrobials tested (n = 18). The remaining 22 (42%) isolates were resistant to 1 or more of the following antimicrobials: kanamycin (2%), streptomycin (38%), spectinomycin (13%), sulfisoxazole (13%), and tetracycline (19%). The following antimicrobial resistance genes were identified: tetA , tetB , sul1 , strA/strB , and aadA. Random amplified polymorphic DNA revealed the majority of our isolates as unrelated and having different patterns, indicating environmental contamination as the primary source of infection. All isolates were shown to be biofilm producers. In conclusion, although antimicrobial resistance was low for both Klebsiella and Raoultella species, genetically related Klebsiella spp. isolates appeared to be more resistant. [ABSTRACT FROM AUTHOR]

Phenol is the major organic pollutant present in industrial waste water. Phenol biodegradation is the most efficient and cost-effective pollutants degradation technologies, it can also ensure a completely degradation of phenol on non toxic products. In this research our objective is to isolate a new bacterial strains with the ability of degrading phenol at high concentrations. Four phenol-degrading bacterium strain were successfully isolated from the effluent of industrial wastewater collected from Telamine Lake in the industrial area in Oran. Based on their morphological, physiological and biochemical characteristics, all the strains were characterized as a Gram-negative, strictly aerobic, no motile and short rod-shaped bacterium that utilize phenol as a sole carbon and energy source. 16S rRNA sequence analysis revealed that these strains ENP1, ENP2, ENP3 and ENP4 were affiliated to Pseudomonas putida, Pseudomonas sp, Raoultella ornithinolytica and Klebisella Sp respectively in the group of Gammaproteo bacteria. All the strains were efficient in removing 99% of the initial 750 mg/L of phenol within 72 h and had a tolerance of phenol concentration as high as 1000 mg/L of phenol. Analysis of the gene of the largest subunit of the multi-component phenol hydroxylase (LmPH) in each isolate showed the presence of this one in all isolate and only the strains ENP1 and ENP2 had the Catechol 2,3-dioxygenases gene (C230). These results indicated that the strains ENP1, ENP2, ENP3 and ENP4 can be exploited for bioremediation of phenol. [ABSTRACT FROM AUTHOR]

Rapid and reliable identification of microorganisms in the clinical laboratory is essential for an early and accurate diagnosis guiding timely therapy. However, conventional methods are sometimes unreliable and show controversial outcomes. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been reported as a rapid and reliable method for identification of bacteria and fungi isolated from clinical samples. Members of the genus Raoultella are increasingly recognized as clinically relevant. There are difficulties in their identification at the species level since sequencing the 16S rRNA or the rpoB genes does not show conclusive results. The aim of this study has been to compare two MALDI-TOF MS systems (Vitek MS and Bruker Biotyper) with Vitek2 and API20E systems for differentiation of Raoultella species. A collection of 97 clinical isolates of Raoultella species was identified with Vitek MS, in parallel with Vitek2 and API, and finally with Bruker Biotyper. Among the two most widely used MALDI-TOF MS platforms, results obtained with Vitek MS were slightly superior to those obtained with the Bruker Biotyper system, with sensitivities and specificities of 98.9/57.9% and 98.8/37.0%, respectively. The current commercial phenotypic identification systems are not optimized for the identification of Raoultella species. Our results indicate that MALDI-TOF-based identification is more accurate and sensitive than that provided by phenotypic methods. [ABSTRACT FROM AUTHOR]

Abstract The removal of diclofenac, which is a widely used non-steroidal anti-inflammatory drug and a dangerous environmental contaminant of surface water, was studied. Its complete degradation by Raoultella sp. KDF8 to primary metabolic products was described with individual metabolites identified by mass spectrometry. The Raoultella strain KDF8 was cultivated with unlabelled and 13C6-labelled diclofenac. A total of 32 compounds were detected as intermediates in diclofenac metabolism by high resolution tandem mass spectrometry. Furthermore, proteomic analysis showed that the presence of diclofenac resulted in the upregulation of 24 enzymes associated with the benzoate, catechol, protocatechuate and ketoadipate pathways. The presence of genes encoding specific enzymes, such as catechol 1,2-dioxygenase, protocatechuate 3,4-dioxygenase and quercetin 2,3-dioxygenase, has been verified by sequence analysis of PCR products. The description of diclofenac metabolism by strain KDF8 provides a detailed view of the degradation of xenobiotic aromatic compounds by microorganisms in general. Highlights • The bacterium Raoultella sp. KDF8 catabolized diclofenac. • 13C-labelled and unlabelled DCF was used to identify biodegradation products (BPs). • 32 BPs were identified by a high resolution tandem electrospray mass spectrometry. • Proteomics revealed upregulation of 24 enzymes of aromatic and ketoadipate pathways. • Key metabolic enzymes were confirmed by the sequence analysis of PCR products. [ABSTRACT FROM AUTHOR]

The genus Raoultella, which belongs to the Enterobacteriaceae family, encompasses gramnegative, oxidase-negative, aerobic, encapsulated and motionless bacilli. Currently, four species of this genus have been described: Raoultella terrigena (R. terrigena), Raoultella planticola (R. planticola), Raoultella ornithinolytica (R. ornithinolytica) and Raoultella electrica (R. electrica), out of which R. planticola and R. ornithinolytica are the most important because of their probable association as pathogenic agents. The incidence of this genus has been underestimated, given that detecting it is really difficult, since it is misidentified as Klebsiella spp. by using manual and automated conventional phenotypic methods. The rapid and correct detection has been increasing since the advent of mass spectrometers (MALDI-TOF MS), which have been used for the differentiation of Klebsiella spp. and Raoultella spp. Currently 80 cases of bacteremia secondary to Raoultella spp. have been identified with different sites of primary infection, which is why it is important to emphasize proper detection in hospitals and healthcare facilities. [ABSTRACT FROM AUTHOR]

Raoultella electrica , a Gram-negative, non-spore-forming, rod-shaped facultative anaerobe, was identified during a regular investigation of bacterial contamination in table eggs in the winter season. A total of 165 hen's eggs were collected in the winter season from 15 different areas of the city of Jaipur, India. Gram-negative Enterobacteriales were isolated on selective and differential media by the conventional plate method and were further identified by several biochemical tests and 16S rRNA gene sequencing. Commonly prescribed antibiotics for enteric infection were used for antibiotic susceptibility testing. For isolated microorganisms, different resistance patterns were found against the different antibiotics used (p < 0.01). The multiple antibiotic resistance index of bacterial isolates ranged from 0.10 to 0.60. R. electrica strain 1GB/NBRC 109676/KCTC 32430 was isolated for the first time from commercial chicken's eggs. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Raoultella planticola is a gram-negative bacterium of the Enterobacteriaceae family that is usually found in soil, plant and aquatic environments. It is an uncommon human pathogen and has been associated with cases of bacteremia, pneumonia, urinary tract infections, among others. Here, we present the case of an 85-year-old female that developed nosocomial pneumonia and bacteremia caused by Raoultella planticola. Pertinent microbiological studies detected carbapenemase production codified by the blaKPC gene. The patient was successfully treated with ceftazidime/avibactam and polymyxin. Our case illustrates the pathogenic potential of this organism and highlights the importance of phenotypic and genotypic assays for the appropriate identification of carbapenemase production.

In recent years the increased consumption of diclofenac, a biologically active compound that is toxic to organisms and persistent to biodegradation, has resulted in its presence in the environment. This is the first report on the biotransformation of diclofenac by a pure bacterial strain, Raoultella sp. DD4, which is able to transform 0.6 mg/L of diclofenac in 28 days. Additionally, strain DD4 is more resistant to diclofenac than other tested organisms. The estimated value for EC50 for this strain is 1.95 g/L. This is approximately five-fold higher than the value of microbial toxic concentration MTCavg (0.416 g/L). Moreover, genotoxicity studies have indicated that diclofenac is not a mutagenic compound. [ABSTRACT FROM AUTHOR]

N2-fixing bacteria belonging to the genus Raoultella of the family Enterobacteriaceae are widely associated with plants. Raoultella sp. strain L03 was isolated from surface-sterilized sugarcane roots. In this study, we inoculated the strain L03 to microbe-free micropropagated plantlets of the main sugarcane cultivar ROC22 grown in Guangxi, China and determined N2-fixation and association between strain L03 and sugarcane plants. Inoculation of strain L03 increased plant biomass, total N, N concentration and chlorophyll, and relieved N-deficiency symptoms of plants under an N-limiting condition. An 15N isotope dilution assay revealed 15N isotope dilution in the inoculated sugarcane plants and incorporation of the fixed 14N from air into chlorophyll. Moreover, a gfp-tagged and antibiotic-resistant L03 strain was reisolated from surface-sterilized sugarcane plants and was detected in plant tissues by fluorescent microscopy. This study for the first time demonstrates that a Raoultella bacterium is able to fix N2 in association with the plant host. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Pathogens from nonpoint sources are the leading cause of water quality impairments in US surface waters. This study assessed the capacity of basidiomycetous fungal mycelium on cellulosic substrates to remove Escherichia coli from synthetic stormwater under unsaturated vertical-flow conditions. The mycelium of Stropharia rugoso-annulata was tested in mycofiltration columns consisting of 18.6 L containers with mycelium grown on either wood chips or a mixture of wood chips and straw. S. rugoso-annulata mycofiltration columns were loaded with water spiked with 600–900 cfu/100 mL of E. coli at low (0.5 L/min; 0.57 m/d) and high (2.2 L/min; 2.5 m/d) hydraulic loading. Influent and effluent were monitored for thermotolerant coliform and E. coli using the Coliscan membrane filter chromogenic method. Alder wood chips infused with S. rugoso-annulata mycelium yielded a removal rate of around 20% relative to control filters. Wood chip and straw media appeared less effective with substantial net export of bacteria from both mycelium-infused and un-inoculated control media. The un-inoculated control media used in this study commonly exported high concentrations of thermotolerant coliform bacteria. On wood chip-based media, the presence of actively growing mycelium reduced the thermotolerant coliform exports by >90% relative to the control media. The study highlights the limitations of using thermotolerant coliform to assess pathogen removal in cellulose rich ecotechnologies like mycofiltration. [ABSTRACT FROM AUTHOR]