Search Results (17)

The presence of antimicrobial-resistant bacteria in fresh produce constitutes a significant public health concern, particularly in rural areas where untreated water is commonly used for irrigation. Certain Enterobacter species have been reported as causal agents of onion bulb rot, with Enterobacter cloacae experimentally demonstrated to cause bulb rot in onions. However, there is poor documentation of its effects in the Vhembe District, South Africa. This study investigated the detection and identification of enteric bacteria in onions, soil, and irrigation water, as well as the characterisation of the identified isolates. Thirty-six samples were analysed, comprising 13 onion samples, 4 irrigation water samples, and 9 soil specimens collected from three farms using selective and differential agar. Identification and enumeration in water and onion samples were performed with the Colilert Quanti-Tray. Physicochemical analysis of irrigation water indicated that Farm 3 had the highest electrical conductivity (EC) and total dissolved solids (TDS), as well as the lowest pH, while Farm 2 exhibited the greatest diversity of pathogenic Escherichia coli pathotypes, including enteroinvasive E. coli (EIEC), which was absent in Farm 3. Culture-based methods yielded 72 presumptive bacterial isolates, which were characterized using the VITEK 2 system. Identified species included Pseudomonas aeruginosa, Klebsiella pneumoniae, Klebsiella oxytoca, Citrobacter amalonaticus, Raoultella ornithinolytica, and members of the Enterobacter cloacae complex. Phylogenetic analysis revealed that most Enterobacter isolates closely matched reference strains of Enterobacter ludwigii. Antimicrobial susceptibility testing against 19 antibiotics demonstrated varied resistance patterns among the isolates. The Enterobacter cloacae complex exhibited the highest resistance (10/19 antibiotics), followed by Klebsiella pneumoniae (9/19) and Citrobacter amalonaticus (7/19). All isolates were resistant to colistin but remained susceptible to ciprofloxacin, with most also sensitive to gentamicin and amikacin. Future research should include additional farms and investigate antibiotic resistance at the genetic level to elucidate its origins. Full article

Growing resistance to carbapenem antibiotics is a major public health problem as these antibiotics are considered the last line of therapy for infections caused by multidrug-resistant (MDR) Gram-negative bacteria. The rapid emergence and dissemination of carbapenem-resistant bacterial strains are mainly due to horizontal gene transfer (HGT) within or between bacterial cells via the mobilome. The aim of this article is to discuss the role of mobile genetic elements (MGEs) that capture and disseminate resistance determinants of carbapenem antibiotics, as a comprehensive review integrating the combined role of plasmids, transposons and integrons. It attempts to systematically fill the gap by investigating the role of these MGEs in the acquisition, mobilization and dissemination of genes encoding carbapenemases across clinically important bacteria. Various types of plasmids such as IncF and IncH in Klebsiella pneumoniae, IncL/M in Enterobacter cloacae, IncX3 in Escherichia coli and IncA/C₂ in Salmonella enterica carry important genes encoding carbapenemases. The rapid distribution of transposons among bacterial species is one of the main contributing factors in the dissemination of carbapenem-resistant isolates. Transposons including Tn4401 carrying bla_KPC in K. pneumoniae and Tn1721 carrying bla_KPC in E. coli; Tn2006, Tn2007, Tn2008 and Tn2009 carrying bla_OXA-23 in Acinetobacter baumannii; Tn1696 carrying bla_IMP-4 in Pseudomonas aeruginosa; Tn125 carrying bla_NDM in E. coli; and Tn6306 carrying bla_IMI in Raoultella ornithinolytica encode different types of carbapenemases. Integrons mainly belonging to class 1 capture resistance determinants for metallo-carbapenemases such as NDM-, VIM-, SIM- and IMP-type enzymes in P. aeruginosa, A. baumannii, K. pneumoniae and E. coli and can promote the transcription and expression of these determinants. These findings are useful for understanding the genetics of carbapenem resistance and additional knowledge on MGEs may provide avenues for screening of resistance to these antibiotics in clinical settings. Full article

Chemical fungicides play a key role in protecting crops, but their use can result in environmental problems. We tested a novel fungicide, composed of endophytic microorganisms, for its effect on wheat yield, grain quality, plant development, and the rhizosphere microbiome, assessed by 16S and ITS metabarcoding. The fungicide increased the grain yield, the effect being similar to a well-known commercial bacterial fungicide, without affecting its quality. Ascomycota, Zygomycota and Mucoromycota together comprised 80% of the mycobiome. Mucoromycota/Mucoromycetes/Rhizopodaceae/Rhizopus arrhizus were significantly decreased. The dominant (≥10%) bacterial phyla were Pseudomonadota, Acidobacteriota, Bacteroidota and Actinomycetota, but their fungicide-related differences were small or random. Different modes of fungicide application (seeds only, seeds plus one or two foliar applications) had no effect on wheat characteristics. Neither of the fungicide’s agents (Raoultella ornithinolytica and Pantoea allii) were found in the rhizosphere. The changes in the mycobiome seemed more pronounced than in the bacteriobiome. The proposed preparation is concluded to have good prospects as a fungicide. However, the low species/strain resolution of the DNA metabarcoding did not allow us to fully interpret shifts in the microbiome diversity, both agronomically and environmentally. These aspects need more comprehensive investigation, using methodology with higher species resolution. Full article

Bloodstream infections are a significant cause of morbidity and mortality among hemodialysis patients. These infections primarily involve Gram-positive bacteria and, less frequently, Gram-negative bacilli. Raoultella ornithinolytica is a Gram-negative bacillus which is known to be a rare opportunistic pathogen. It is found only occasionally in human infections; however, it has been noted as an emerging pathogen. Sepsis caused by this microorganism is very rare. A few cases have been reported among immunocompromised patients or those undergoing invasive procedures. Cases involving urinary catheters or port catheters have also been reported, as well as a single case of a patient on peritoneal dialysis. Here, we present a novel case of Raoultella ornithinolytica bloodstream infection in a patient with chronic renal failure undergoing hemodialysis who was successfully treated. We discuss the microbiology and clinical features of such infections, and consider aspects of treatment. Full article

Regarding the trout microbiota, most information is focused on lactic acid bacteria, which can show beneficial properties. However, in trout farming, mostly pathogenic Gram-positive species were reported, such as Staphylococcus aureus, Listeria monocytogenes, and/or Clostridium spp. In this study, free-living trout were analyzed for Gram-negative microbiota that can cause loss as disease-stimulating agents. Bacteriocin postbiotics should be one of the approaches used to eliminate these agents. In total, 21 strains of different species isolated from the intestinal tract of 50 trout in Slovakia (Salmo trutta and Salmo gairdnerii) were taxonomically allotted into 13 species and 9 genera. This method showed variability in microbiota identified using MALDI-TOF mass spectrometry with the following species: Acinetobacter calcoaceticus, Citrobacter gillenii, Citrobacter freundii, Escherichia coli, Hafnia alvei, Kluyvera cryocrescens, K. intermedia, Leclercia adecarboxylata, Raoultella ornithinolytica, Pseudomonas fragi, Ps. putida, Ps. lundensis, Ps. teatrolens, and Serratia fonticola. Most strains were susceptible to the antibiotics used, reaching inhibitory zones up to 29 mm. On the other hand, 3 out of 21 strains (14%) were susceptible to nine enterocins- postbiotics (Hafnia alvei Hal281, Pseudomonas putida Pp391, and Ps. fragi Pf 284), with inhibitory activity in the range of 100–6400 AU/mL. Full article

Antimony-resistant bacteria are potential natural resources for the bioremediation of mining soil pollution. A Raoultella sp. 64 strain was isolated from antimony-contaminated soil. To enhance its Sb resistance abilities, this strain was transported into space aboard the Shenzhou spacecraft for space breeding, resulting in a mutant strain, Raoultella sp. D9. The whole genomes of Raoultella sp. 64 and mutant strain Raoultella sp. D9 were sequenced, revealing the genomic information for the bacterium. Comparative genomic analysis was then carried out to identify differential functional genes. The adsorption conditions for Sb(III) were optimized and refined. Further, Fourier transform infrared spectroscopy (FTIR) was used to determine the adsorption of antimony. Results show that strain D9 exhibits a higher tolerance to Sb(III), and Sb resistance genes were identified in both Raoultella sp. 64 and D9. Analysis of the differential functional genes indicated that the increased copy number of plsX may lead to a higher lipid content in the cell membrane, thereby enhancing the cell’s resistance to heavy metals. Mutant strain D9 exhibited better biosorption capacity compared to strain 64. FTIR studies showed that key functional groups, including -OH, C-N, C-H, and C-O, are likely to have participated in Sb(III) biosorption. Further study of the differential functional genes could provide a basis for future research and the subsequent development of technologies for the remediation of Sb-contaminated sites. Full article

In this study, we determined and identified the bacterial diversity of different types of artisanal and industrially produced cheese. The antibiotic (erythromycin, chloramphenicol, kanamycin, ampicillin, clindamycin, streptomycin, tetracycline, and gentamicin) and biocide (peracetic acid, sodium hypochlorite, and benzalkonium chloride) resistance of clinically relevant bacteria was determined as follows: Staphylococcus aureus, Macrococcus caseolyticus, Bacillus sp., Kocuria varians, Escherichia coli, Enterococcus faecalis, Citrobacter freundii, Citrobacter pasteurii, Klebsiella oxytoca, Klebsiella michiganensis, Enterobacter sp., Enterobacter cloacae, Enterobacter sichuanensis, Raoultella ornithinolytica, Shigella flexneri, and Salmonella enterica. Also, the effect of the sub-inhibitory concentration of three biocides on antibiotic resistance was determined. The microbiota of evaluated dairy products comprise diverse and heterogeneous groups of bacteria with respect to antibiotic and disinfectant tolerance. The results indicated that resistance was common in the case of ampicillin, chloramphenicol, erythromycin, and streptomycin. Bacillus sp. SCSSZT2/3, Enterococcus faecalis SRGT/1, E. coli SAT/1, Raoultella ornithinolytica MTT/5, and S. aureus SIJ/2 showed resistance to most antibiotics. The tested bacteria showed sensitivity to peracetic acid and a different level of tolerance to benzalkonium chloride and sodium hypochlorite. The inhibition zone diameter of antibiotics against Enterococcus faecalis SZT/2, S. aureus JS11, E. coli CSKO2, and Kocuria varians GRT/10 was affected only by the sub-inhibitory concentration of peracetic acid. Full article

Raoultella ornithinolytica is an Enterobacteriaceae bacterium that can infect both humans and animals, while luteolin-7-O-glucoside (IOG) is a flavonoid that has broad effects on the intestinal microbiota of healthy animals. However, current studies lack sufficient data on intestinal microbiota dysbiosis and drug resistance transmission caused by R. ornithinolytica and the possible role of IOG. In this study, BALB/c mice were infected with R. ornithinolytica carrying bla_NDM-1 gene and treated with IOG (3 mg/kg·d and 6 mg/kg·d) to analyze the diversity of intestinal microbiota and the transfer of bla_NDM-1 between bacteria. The findings indicated that R. ornithinolytica B1645-1 exhibited a significant ability to enhance the Firmicutes/Bacteroidota ratio and increase the relative abundance of Lactobacillus and Bacillus after 48 h, where as 6 mg/kg·d IOG had an opposite effect. Moreover, R. ornithinolytica B1645-1 facilitated the emergence of drug-resistant bacteria and promoted bla_NDM-1 gene transfer in Enterococcus, Escherichia, Klebsiella, Acinetobacter, Bacillus, Brevibacterium, and Lactobacillus. Enterococcus was the predominant genus at 48 h. Surprisingly, 6 mg/kg·d IOG significantly inhibited the production of drug-resistant bacteria and promoted bla_NDM-1 gene transfer from Enterococcus to Lactobacillus at 144 h. However, the role of Lactobacillus as a recipient for drug-resistant genes should be of more concern. Full article

The stability of symbiotic flora is an important indicator of the health of an organism. Symbiotic bacteria have been proven to be closely involved in the immune process of organisms. The pathogenicity of Beauveria bassiana was studied in relation to symbiotic bacteria on the surface and inside of the migratory locust (Locusta migratoria). The results showed that the surface disinfection of test locusts contributed to the pathogenicity of B. bassiana to locusts. Most of the surface bacteria of L. migratoria caused some inhibition of B. bassiana growth, and LM5-4 (Raoultella ornithinolytica), LM5-2 (Enterobacter aerogenes), and LM5-13 (Citrobacter freundii) showed the highest inhibitory effect on the growth of B. bassiana. The inoculation of locusts with additional surface symbiotic bacteria reduced the virulence of B. bassiana to L. migratoria. Infection by different strains of B. bassiana caused similar changes in the symbiotic flora of migratory locusts. The inoculation of locusts with additional intestinal symbiotic bacteria (Enterobacter sp.) reduced the virulence of B. bassiana to L. migratoria. These findings illustrate the effect of bacterial communities on fungal infections in L. migratoria when seen from the perspective of ecology in a microenvironment. The active antifungal substances of such bacteria and their mechanisms of action need further study. Full article

The available data on antimicrobial resistance in pets are limited compared to those collected for food-producing animals. Bacterial urinary tract infections are some of the most important indications for antimicrobial use in pets, and empiric antimicrobial treatments are often administered in the presence of clinical signs. In this study, the results obtained from the laboratory investigations carried out on dogs and cats with urinary tract infections coming from veterinary clinics and practices in Central Italy were evaluated to provide additional data concerning the bacterial urinary pathogens and their antimicrobial resistance patterns in pets. A total of 635 isolates were collected from urine samples. Escherichia coli was the most common species recovered in dogs and cats, followed by Proteus mirabilis and Enterococcus spp. Furthermore, it was possible to isolate bacteria not usually described in other studies concerning pets such as Pantoea dispersa, Raoultella ornithinolytica, and Pasteurella pneumotropica (also known as Rodentibacter pneumotropicus). Based on the antimicrobial susceptibility results, 472/635 (74.3%) isolates were resistant to at least one antibiotic and 285/635 (44.8%) isolates were classified as multidrug-resistant. Monitoring the antibiotic resistance profiles in pet infections is important not only for the public health implications, but also to collect data useful for the treatment of diseases in pets. Full article

The emergence and spread of antimicrobial resistance (AMR) has become a persistent problem globally. In this study, an ozone treatment facility was established for an advanced hospital wastewater treatment in a core hospital facility in an urban area in Japan to evaluate the inactivation of antimicrobial-resistant bacteria and antimicrobials. Metagenomic DNA-seq analysis and the isolation of potential extended-spectrum β-lactamase (ESBL)-producing bacteria suggested that ozone exposure for at least 20 min is required for the adequate inactivation of DNA and ESBL-producing bacteria. Escherichia coli and Klebsiella species were markedly susceptible to 20-min ozone exposure, whereas Raoultella ornithinolytica and Pseudomonas putida were isolated even after an 80-min exposure. These ozone-resistant bacteria might play a pivotal role as AMR reservoirs in the environment. Nine antimicrobials (ampicillin, cefdinir, cefpodoxime, ciprofloxacin, levofloxacin, clarithromycin, chlortetracycline, minocycline, and vancomycin) were detected at 373 ng/L to 27 μg/L in the hospital wastewater, and these were removed (96–100% removal) after a 40-min treatment. These results facilitate a comprehensive understanding of the AMR risk posed by hospital wastewater and provides insights for devising strategies to eliminate or mitigate the burden of antimicrobial-resistant bacteria and the flow of antimicrobials into the environment. To the best of our knowledge, this is the first report on the implementation of a batch-type, plant-scale ozone treatment system in a hospital facility to execute and evaluate the inactivation of drug-resistant bacteria and antimicrobials. Full article

Histamine is a toxic biogenic amine commonly found in seafood products or their derivatives. This metabolite is produced by histamine-producing bacteria (HPB) such as Proteus vulgaris, P. mirabilis, Enterobacter aerogenes, E. cloacae, Serratia fonticola, S. liquefaciens, Citrobacter freundii, C. braakii, Clostridium spp., Raoultella planticola, R. ornithinolytica, Vibrio alginolyticus, V. parahaemolyticus, V. olivaceus, Acinetobacter lowffi, Plesiomonas shigelloides, Pseudomonas putida, P. fluorescens, Aeromonas spp., Photobacterium damselae, P. phosphoreum, P. leiognathi, P. iliopiscarium, P. kishitanii, and P. aquimaris. In this review, the role of these bacteria in histamine production in fish and seafood products with consequences for human food poisoning following consumption are discussed. In addition, methods to control their activity in countering histamine production are proposed. Full article

Klebsiella spp. is a relevant pathogen that can present acquired resistance to almost all available antibiotics, thus representing a serious threat for public health. While most studies have been focused on isolates causing community-acquired and nosocomial infections, little is known about the commensal isolates colonizing healthy subjects. We describe the molecular identification and the phenotypic characterization of commensal Klebsiella spp. from breast milk of healthy women and faeces from healthy breast-fed infants, which were compared with isolates from community-acquired infections and from a nosocomial NICU outbreak. The phylogenetic analysis of a 454-bp sequence of the rpoB gene was useful for species identification (K. pneumoniae, K. variicola, K. quasipneumoniae, K. oxytoca, K. grimontii, K. michiganensis, Raoultella planticola and R. ornithinolytica), previously misidentified as K. pneumoniae or K. oxytoca by biochemical methods. Globally, we report that commensal strains present virulence traits (virulence genes, siderophores and biofilms) comparable to community-acquired and NICU-infective isolates, thus suggesting that the human microbiota could constitute a reservoir for infection. Isolates causing NICU outbreak were multi-drug resistant (MDR) and ESBLs producers, although an imipenem-resistant commensal MDR K. quasipneumoniae isolate was also found. A commensal K. pneumoniae strain showed a potent bacteriocin-like inhibitory activity against MDR Klebsiella isolates, thus highlighting the potential role of commensal Klebsiella spp. in health and disease. Full article

Aquaculture is a growing sector, providing several products for human consumption, and it is therefore important to guarantee its quality and safety. This study aimed to contribute to the knowledge of bacterial composition of Crassostrea gigas, Mytilus spp. and Ruditapes decussatus, and the antibiotic resistances/resistance genes present in aquaculture environments. Two hundred and twenty-two bacterial strains were recovered from all bivalve mollusks samples belonging to the Aeromonadaceae, Bacillaceae, Comamonadaceae, Enterobacteriaceae, Enterococcaceae, Micrococcaceae, Moraxellaceae, Morganellaceae, Pseudomonadaceae, Shewanellaceae, Staphylococcaceae, Streptococcaceae, Vibrionaceae, and Yersiniaceae families. Decreased susceptibility to oxytetracycline prevails in all bivalve species, aquaculture farms and seasons. Decreased susceptibilities to amoxicillin, amoxicillin/clavulanic acid, cefotaxime, cefoxitin, ceftazidime, chloramphenicol, florfenicol, colistin, ciprofloxacin, flumequine, nalidixic acid and trimethoprim/sulfamethoxazole were also found. This study detected six qnrA genes among Shewanella algae, ten qnrB genes among Citrobacter spp. and Escherichia coli, three oqxAB genes from Raoultella ornithinolytica and bla_TEM-1 in eight E. coli strains harboring a qnrB19 gene. Our results suggest that the bacteria and antibiotic resistances/resistance genes present in bivalve mollusks depend on several factors, such as host species and respective life stage, bacterial family, farm’s location and season, and that is important to study each aquaculture farm individually to implement the most suitable measures to prevent outbreaks. Full article

Background: The study examined the oral microbiota, physiological and immunological changes in patients using thermoplastic retainers during three months of use. Methods: The study included several steps. Firstly, 10 swabs were collected from the buccal and palatal surfaces of the teeth of the patients, approximately 2 mL of saliva was collected from the same patients and 2 mL of saliva was collected from 10 healthy people to measure the pH and secretory IgA level. This was followed by the isolation and identfication of the bacterial isolates in the patient samples. Then, isolate susceptibility toward chlorhexidine (CHX) and their adhesion ability to thermoplastic retainer surfaces was measured. In addition to that the study estimated the numbers of Lactobacillus and Streptooccus mutans colonies during three months and finally, a comparsion of pH acidity and IgA level between the patients and healthy people was performed. The results showed the predominant bacteria during the three months were Lactobacillus spp. and Streptococcus spp. followed by different rates of other bacteria. Raoultella ornithinolytica showed more resistance to CHX while Lactobacillus spp. showed more sensitivity. Streptococcus mutans colony levels were higher than Lactobacillus spp. colonies during the three months, also S. mutans had the highest value in adherence to retainer thermoplastic. Finally, pH acidity showed a highly significant difference (p ≤ 0.05) in the third month, like IgA levels (p ≤ 0.05). Conclusions: According to the results obtained from the current study, the researchers noted that the thermoplastic retainers helped change the oral cavity environment. Full article