Cluster and sporadic cases of herbaspirillum species infections in patients with cancer

An unusual case of Herbaspirillum huttiense bacteraemia in a haemodialysis patient

Herbaspirillum spp. is a common environmental bacterium usually found in soil, plant roots, and water. It is rarely associated with infection in immunocompromised patients, and rarely reported infections in immunocompetent patients. We report the first case of a Herbaspirillum huttiense bacteraemia in a non-neutropenic home haemodialysis patient. A 57-year-old male presented to our hospital with a 3-day history of malaise, fevers, rigours, and anorexia following dialysis through his central line. On examination, he was pyrexic (temperature 38.7°C) with splinter haemorrhages noted, but no other signs of infection were present. Blood cultures revealed a polymicrobial infection, with Serratia liquefaciens and Corynebacterium jeikeium isolated from the central line and Herbaspirillum sp. was isolated from both the central line and a peripheral culture. A later peripheral blood culture following central line removal isolated Herbaspirillum huttiense. Regular biological testing of his home water supply and dialysate detected no colony forming units of non-fermenting gram-negative bacilli. He was initially treated with ceftriaxone and vancomycin initially, followed by ertapenem and vancomycin. Intravenous antibiotics were ceased following 5 days after central line removal and he made an uneventful recovery.

Catheter-related Infections in Pediatric Patients Due to a Rare Pathogen: Herbaspirillum huttiense

BACKGROUND

Herbaspirillum species are nonfermenting, aerobic, helical or curved, Gram-negative bacteria belonging to the class Betaproteobacteria, order Burkholderiales. To date, only a few studies have reported on the epidemiology, clinical symptoms, antibiotic susceptibility profiles, treatment and outcomes of Herbaspirillum huttiense -related infections in pediatric patients.

METHODS

The aim of this study was to present 3 years of H.huntiense data, antibiotic susceptibility profiles, systemic antibiotics and antibiotic lock therapy (ALT) options and clinical outcomes.

RESULTS

Fourteen episodes of infection in 12 patients were included in this retrospective study. The patients had a male/female ratio of 1:1 and a median age of 160.5 months (range, 3-198 months). Catheter-related bloodstream infection (CRBSI) was detected in 11 patients. Only 1 patient developed catheter-related infective endocarditis. The patient's catheter was removed, and she was successfully treated with systemic antibiotics for 4 weeks. Systemic antibiotics were used in all infections related to H. huttiense . In septic, critically ill patients, the catheter was removed, and systemic antibiotics were started. Port catheters were removed in 5 patients. ALT was performed in clinically stable patients. ALT using amikacin was administered to 6 patients through the port catheter. Two patients had a 2nd attack. After the 2nd ALT treatment, 1 patient cured, and the catheter of the other patient was removed due to persistent microbial growth in cultures. Antimicrobial susceptibility testing of the reported isolates showed susceptibility to meropenem (90%), ceftazidime (87%) and piperacillin/tazobactam (65%), with 92% resistance to colistin.

CONCLUSION

H. huttiense is an emerging pathogen in CRBSI. Piperacillin/tazobactam, ceftazidime and meropenem appear to be good therapeutic options for the treatment of H. huttiense infections. ALT and systemic antibiotics can be used in H. huttiense -CRBSI to sterilize and preserve the central venous catheter.

Opportunistic pathogen Porphyromonas gingivalis targets the LC3B-ceramide complex and mediates lethal mitophagy resistance in oral tumors

Mechanisms by which Porphyromonas gingivalis (P. gingivalis) infection enhances oral tumor growth or resistance to cell death remain elusive. Here, we determined that P. gingivalis infection mediates therapeutic resistance via inhibiting lethal mitophagy in cancer cells and tumors. Mechanistically, P. gingivalis targets the LC3B-ceramide complex by associating with LC3B via bacterial major fimbriae (FimA) protein, preventing ceramide-dependent mitophagy in response to various therapeutic agents. Moreover, ceramide-mediated mitophagy is induced by Annexin A2 (ANXA2)-ceramide association involving the E142 residue of ANXA2. Inhibition of ANXA2-ceramide-LC3B complex formation by wild-type P. gingivalis prevented ceramide-dependent mitophagy. Moreover, a FimA-deletion mutant P. gingivalis variant had no inhibitory effects on ceramide-dependent mitophagy. Further, 16S rRNA sequencing of oral tumors indicated that P. gingivalis infection altered the microbiome of the tumor macroenvironment in response to ceramide analog treatment in mice. Thus, these data provide a mechanism describing the pro-survival roles of P. gingivalis in oral tumors.

Machine learning: a powerful tool for identifying key microbial agents associated with specific cancer types

Machine learning (ML) includes a broad class of computer programs that improve with experience and shows unique strengths in performing tasks such as clustering, classification and regression. Over the past decade, microbial communities have been implicated in influencing the onset, progression, metastasis, and therapeutic response of multiple cancers. Host-microbe interaction may be a physiological pathway contributing to cancer development. With the accumulation of a large number of high-throughput data, ML has been successfully applied to the study of human cancer microbiomics in an attempt to reveal the complex mechanism behind cancer. In this review, we begin with a brief overview of the data sources included in cancer microbiomics studies. Then, the characteristics of the ML algorithm are briefly introduced. Secondly, the application progress of ML in cancer microbiomics is also reviewed. Finally, we highlight the challenges and future prospects facing ML in cancer microbiomics. On this basis, we conclude that the development of cancer microbiomics can not be achieved without ML, and that ML can be used to develop tumor-targeting microbial therapies, ultimately contributing to personalized and precision medicine.

Artificial intelligence-enabled microbiome-based diagnosis models for a broad spectrum of cancer types

Microbiome-based diagnosis of cancer is an increasingly important supplement for the genomics approach in cancer diagnosis, yet current models for microbiome-based diagnosis of cancer face difficulties in generality: not only diagnosis models could not be adapted from one cancer to another, but models built based on microbes from tissues could not be adapted for diagnosis based on microbes from blood. Therefore, a microbiome-based model suitable for a broad spectrum of cancer types is urgently needed. Here we have introduced DeepMicroCancer, a diagnosis model using artificial intelligence techniques for a broad spectrum of cancer types. Built based on the random forest models it has enabled superior performances on more than twenty types of cancers' tissue samples. And by using the transfer learning techniques, improved accuracies could be obtained, especially for cancer types with only a few samples, which could satisfy the requirement in clinical scenarios. Moreover, transfer learning techniques have enabled high diagnosis accuracy that could also be achieved for blood samples. These results indicated that certain sets of microbes could, if excavated using advanced artificial techniques, reveal the intricate differences among cancers and healthy individuals. Collectively, DeepMicroCancer has provided a new venue for accurate diagnosis of cancer based on tissue and blood materials, which could potentially be used in clinics.

Analysis of Gut Microbiome Structure Based on GMPR+Spectrum

The gut microbiome is related to many major human diseases, and it is of great significance to study the structure of the gut microbiome under different conditions. Multivariate statistics or pattern recognition methods were often used to identify different structural patterns in gut microbiome data. However, these methods have some limitations. Minimal hepatic encephalopathy (MHE) datasets were taken as an example. Due to the physical lack or insufficient sampling of the gut microbiome in the sequencing process, the microbiome data contains many zeros. Therefore, the geometric mean of pairwise ratios (GMPR) was used to normalize gut microbiome data, then Spectrum was used to analyze the structure of the gut microbiome, and lastly, the structure of core microflora was compared with Network analysis. GMPR calculates the Intraclass correlation coefficient (ICC), whose reproducibility was significantly better than other normalization methods. In addition, running-time, Normalized Mutual Information (NMI), Davies-Boulding Index (DBI), and Calinski-Harabasz index (CH) of GMPR+Spectrum were far superior to other clustering algorithms such as M3C, iClusterPlus. GMPR+Spectrum can not only perform better but also effectively identify the structural differences of intestinal microbiota in different patients and excavate the unique critical bacteria such as Akkermansia, and Lactobacillus in MHE patients, which may provide a new reference for the study of the gut microbiome in disease.

Non-Alcoholic Components in Huangjiu as Potential Factors Regulating the Intestinal Barrier and Gut Microbiota in Mouse Model of Alcoholic Liver Injury

Different alcoholic beverages and drinking patterns might exert divergent impacts on alcoholic liver disease (ALD) progression. Whether the abundant non-alcoholic components (NAC) in fermented wine could alleviate ethanol (EtOH)-induced adverse influences on the liver remains unknown. Hence, the chronic ALD mouse model was established to compare the effects of Huangjiu (a typical fermented wine) and EtOH feeding on the liver, intestinal barrier, gut microbiota, and intestinal short-chain fatty acids (SCFAs) content. Although Huangjiu intake led to slight hepatic steatosis, it mitigated oxidative stress, inflammation, and intestinal damage relative to EtOH intake. In comparison with EtOH feeding, Huangjiu significantly improved the intestinal barrier integrity and reduced hepatic lipopolysaccharide levels by up-regulating the expression of intestinal tight junction proteins (ZO-1 and occludin) and antimicrobial activity peptides (Reg3β and Reg3γ). The administration of Huangjiu NAC partially restored alcohol-induced gut microbiota dysbiosis via recovering the abundance of Lactobacillus, Faecalibaculum, and Akkermansia. Moreover, mice receiving Huangjiu showed higher SCFAs levels (such as acetic acid and butyric acid) than those receiving EtOH. Huangjiu consumption resulted in lower hepatotoxicity than pure EtOH, at the same alcohol dose. The NAC in Huangjiu might attenuate the progression of ALD by regulating intestinal barrier function and microbiota-meditated gut ecology.

Quality of dialysis water and dialysate in hemodialysis centers: highlight for occurrence of non-fermenting gram-negative bacilli

AIMS

To evaluate the physicochemical and microbiological quality of dialysis water and dialysate samples from hemodialysis centers.

METHODS AND RESULTS

Samples were fortnightly collected from three hemodialysis centers in Bauru City, Brazil, between July/2017 and June/2018, at the stages of post-reverse osmosis, reuse and dialysate. Analyses included determination of conductivity, fluoride, nitrate and sulfate; test for total coliform bacteria; count of heterotrophic bacteria; count and identification of non-fermenting gram-negative bacilli (NFGNB); drug susceptibility test; biofilm formation capacity, and genetic similarity among some isolated NFGNB. Of the analyzed samples, only 4/72 (5.6%) had conductivity values ≥ 10 mS/cm, 4/216 (1.9%) presented total coliforms, and 1/216 (0.5%) had heterotrophic bacteria count > 100 CFU/mL. NFGNB were isolated from 99/216 (45.8%) samples, and the major identified microorganisms included Herbaspirillum aquaticum/huttiense, Brevundimonas aurantiaca, Cupriavidus metallidurans, Pseudomonas aeruginosa and Ralstonia insidiosa. Isolates of P. aeruginosa and Burkholderia cepacia complex were sensitive to most antimicrobials and, together with isolates of Ralstonia insidiosa and Ralstonia pickettii, showed strong biofilm formation capacity. Some isolates expressed the same electrophoretic profile on pulsed-field gel electrophoresis, indicating persistence of bacterial clones in the systems over time.

CONCLUSIONS

NFGNB were observed in several dialysis water and dialysate samples from all investigated centers, which may represent a risk to the health of patients.

SIGNIFICANCE AND IMPACT OF THE STUDY

Regular inclusion of actions for NFGNB control and monitoring in hemodialysis fluids are suggested for greater safety of the dialytic process.

High Genomic Identity between Clinical and Environmental Strains of Herbaspirillum frisingense Suggests Pre-Adaptation to Different Hosts and Intrinsic Resistance to Multiple Drugs

The genus Herbaspirillum is widely studied for its ability to associate with grasses and to perform biological nitrogen fixation. However, the bacteria of the Herbaspirillum genus have frequently been isolated from clinical samples. Understanding the genomic characteristics that allow these bacteria to switch environments and become able to colonize human hosts is essential for monitoring emerging pathogens and predicting outbreaks. In this work, we describe the sequencing, assembly, and annotation of the genome of H. frisingense AU14559 isolated from the sputum of patients with cystic fibrosis, and its comparison with the genomes of the uropathogenic strain VT-16-41 and the environmental strains GSF30, BH-1, IAC152, and SG826. The genes responsible for biological nitrogen fixation were absent from all strains except for GSF30. On the other hand, genes encoding virulence and host interaction factors were mostly shared with environmental strains. We also identified a large set of intrinsic antibiotic resistance genes that were shared across all strains. Unlike other strains, in addition to unique genomic islands, AU14559 has a mutation that renders the biosynthesis of rhamnose and its incorporation into the exopolysaccharide unfeasible. These data suggest that H. frisingense has characteristics that provide it with the metabolic diversity needed to infect and colonize human hosts.

Differential exopolysaccharide production and composition by Herbaspirillum strains from diverse ecological environments

Bacteria belonging to the genus Herbaspirillum are found in many different ecological niches. Some species are typically endophytic, while others were reported as free-living organisms that occupy various environments. Also, opportunistic herbaspirilli have been found infecting humans affected by several diseases. We have analyzed the production of exopolysaccharides (EPS) by Herbaspirillum strains isolated from different sources and with distinct ecological characteristics. The monosaccharide composition was determined for the EPS obtained for selected strains including free-living, plant-associated and clinical isolates, and the relationship with the ecological niches occupied by Herbaspirillum spp. is proposed.

Environmental and clinical isolates of Herbaspirillum induce pulmonary infection in mice and its secretome is cytotoxic to human lung cells

Introduction. In recent years, the Herbaspirillum genus has emerged as a pathogen in healthcare-related infections and has became stablished as an opportunistic pathogen.Hypothesis/Gap Statement. Little is known about the pathogenesis induced by Herbaspirillum genus.Aim. To evaluate the cytotoxic effects of genus Herbaspirillum, its ability to adhere to lung human cells and the ability of environmental and clinical strains of Herbaspirillum to induce pneumonia in mice.Methodology. Environmental and clinical isolates of Herbaspirillum were examined for their cytotoxic effects on the Calu-3 cell lineage. Cytotoxic activity of secretome was tested using MTT/neutral red assays and cell morphology analysis. Herbaspirillum adhesion on Calu-3 cells was assessed using bright-field microscopy and cell-associated bacteria were counted. A mouse model of acute lung infection was done using a clinical and an environmental strain. Adult male mice were used, and the pneumonia was inducted by intra-tracheal inoculation of 10⁸ or 10⁹ bacteria. Mice weight variations were evaluated at the end of the experiment. Bronchoalveolar lavage was collected and evaluated for total and differential cytology. A histological examination of lungs was performed giving a histological score.Results. The secretomes of all the strains induced morphological alterations in cells, but only H. seropedicae SmR1 were cytotoxic in MTT and neutral red assays. Clinical strains of H. frisingense AU14459 and H. hutttiense subsp. huttiense AU11883 exhibited low adherence to lung cells, while SmR1 was non-adhesive. Following intratracheal inoculation, mice treated with 10⁹ c.f.u. of the SmR1 and AU11883 strains lost 18 and 6% of their weight over 7 days, respectively, and presented moderate clinical signs. Infected mice showed inflammatory cell infiltration in the perivascular and peribroncheal/peribronchiolar spaces. Bronchoalveolar fluid of mice inoculated with SmR1 10⁹ c.f.u. presented an increase in total leucocyte cells and in neutrophils population.Conclusion. These in vivo and in vitro results provide insights into how some Herbaspirillum strains cause infection in humans, providing a basis for the characterization of pathogenesis studies on this emerging infectious agent.

Rumen microbiome structure and metabolites activity in dairy cows with clinical and subclinical mastitis

Background

Due to the high prevalence and complex etiology, bovine mastitis (BM) is one of the most important diseases to compromise dairy cow health and milk quality. The shift in milk compositions has been widely investigated during mastitis, but recent studies suggested that gastrointestinal microorganism also has a crucial effect on the inflammation of other peripheral tissues and organs, including the mammary gland. However, research focused on the variation of rumen inner-environment during mastitis is still limited. Therefore, the ruminal microbial profiles, metabolites, and milk compositions in cows with different udder health conditions were compared in the present study. Furthermore, the correlations between udder health status and ruminal conditions were investigated. Based on the somatic cell counts (SCC), California mastitis test (CMT) parameters and clinical symptoms of mastitis, 60 lactating Holstein dairy cows with similar body conditions (excepted for the udder health condition) were randomly divided into 3 groups (n = 20 per group) including the healthy (H) group, the subclinical mastitis (SM) group and the clinical mastitis (CM) group. Lactation performance and rumen fermentation parameters were recorded. And rumen microbiota and metabolites were also analyzed via 16S rRNA amplicon sequencing and untargeted metabolomics, respectively.

Results

As the degree of mastitis increased, rumen lactic acid (LA) (P < 0.01), acetate, propionate, butyrate, valerate (P < 0.001), and total volatile fatty acids (TVFAs) (P < 0.01) concentrations were significantly decreased. In the rumen of CM cows, the significantly increased bacteria related to intestinal and oral inflammation, such as Lachnospiraceae (FDR-adjusted P = 0.039), Moraxella (FDR-adjusted P = 0.011) and Neisseriaceae (FDR-adjusted P = 0.036), etc., were accompanied by a significant increase in 12-oxo-20-dihydroxy-leukotriene B4 (FDR-adjusted P = 5.97 × 10^− 9) and 10beta-hydroxy-6beta-isobutyrylfuranoeremophilane (FDR-adjusted P = 3.88 × 10^− 10). Meanwhile, in the rumen of SM cows, the Ruminiclostridium_9 (FDR-adjusted P = 0.042) and Enterorhabdus (FDR-adjusted P = 0.043) were increased along with increasing methenamine (FDR-adjusted P = 6.95 × 10^− 6), 5-hydroxymethyl-2-furancarboxaldehyde (5-HMF) (FDR-adjusted P = 2.02 × 10^− 6) and 6-methoxymellein (FDR-adjusted P = 2.57 × 10^− 5). The short-chain fatty acids (SCFAs)-producing bacteria and probiotics in rumen, including Prevoterotoella_1 (FDR-adjusted P = 0.045) and Bifidobacterium (FDR-adjusted P = 0.035), etc., were significantly reduced, with decreasing 2-phenylbutyric acid (2-PBA) (FDR-adjusted P = 4.37 × 10^− 6).

Conclusion

The results indicated that there was a significant shift in the ruminal microflora and metabolites associated with inflammation and immune responses during CM. Moreover, in the rumen of cows affected by SM, the relative abundance of several opportunistic pathogens and the level of metabolites which could produce antibacterial compounds or had a competitive inhibitory effect were all increased.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40104-020-00543-1.

Bloodstream infection due to Herbaspirillum sp.: case series and review of literature

Herbaspirillum species are Gram-negative bacteria belonging to the class Betaproteobacteria, order Burkholderiales. The phylogenetic and phenotypic similarities among these groups easily lead to species misidentification. Herbaspirillum bacteraemia is an uncommon clinical entity. The objective of this review is to collect information to contribute to the management of this infection. We describe our own case series and review the cases reported in the literature. Cancer appears as the major underlying disease. The main source of bacteraemia was respiratory. Phenotypic identification methods often misidentify this species. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and molecular methods identify at genus level, but species assignment is not reliable. Herbaspirillum spp. showed a highly susceptible antimicrobial profile. β-Lactams showed good activity with low MIC values, except ampicillin. All isolates were resistant to colistin, suggesting an intrinsic resistance mechanism. Herbaspirillum spp. is an uncommon pathogen. MALDI-TOF MS or molecular methods are necessary to achieve a reliable genus identification. These species are not multidrug resistant. Piperacillin/tazobactam or ceftazidime might be a good treatment for this microorganism.

Herbaspirillum Infection in Humans: A Case Report and Review of Literature

Introduction. Herbaspirillum seropedicae are Gram-negative oxidase-positive nonfermenting rods of Betaproteobacteria class, commonly found in rhizosphere. More recently, some Herbaspirillium species have transitioned from environment to human hosts, mostly as opportunistic (pathogenic) bacteria. We present a 58-year-old female with non-small-cell lung cancer (NSCLC) who presented with pneumonia and was found to have Herbaspirillum seropedicae bacteremia. Case History. A 58-year-old woman with NSCLC on Pralsetinib presented with fevers and rigors for 2 days. Coarse breath sounds were auscultated on the right upper lung field. Labs revealed leukopenia and mild neutropenia. CT chest revealed right upper lobe pneumonia. She was admitted for sepsis secondary to pneumonia and placed on broad spectrum antibiotics with intravenous piperacillin-tazobactam and vancomycin. The patient continued to have fever 2 days after admission (max: 102.8°F). Preliminary blood cultures grew Gram-negative rods. The patient continued to have temperature spikes on the 3rd day of antibiotics (T_max 101.5°F). Blood cultures revealed oxidase-positive nonfermenting rods. The patient's antibiotic was changed to IV meropenem on the 4th day of hospitalization. Ultimately, on the seventh day of hospitalization, the blood culture was confirmed from outside lab as Herbaspirillum seropedicae. The patient started feeling better and defervesced after about 24 hours. Discussion. More recently, Herbaspirillum spp. have been recovered from humans. Our patient had Herbaspirillum bacteremia, and reported regularly cleaning her pond and weeding her garden with possible exposure to this environmental proteobacterium. Herbaspirillum may be more prevalent than earlier thought owing to misidentification. With the institution of appropriate antimicrobial therapy, the outcomes seem mostly favorable.

Genome comparison between clinical and environmental strains of Herbaspirillum seropedicae reveals a potential new emerging bacterium adapted to human hosts

BACKGROUND

Herbaspirillum seropedicae is an environmental β-proteobacterium that is capable of promoting the growth of economically relevant plants through biological nitrogen fixation and phytohormone production. However, strains of H. seropedicae have been isolated from immunocompromised patients and associated with human infections and deaths. In this work, we sequenced the genomes of two clinical strains of H. seropedicae, AU14040 and AU13965, and compared them with the genomes of strains described as having an environmental origin.

RESULTS

Both genomes were closed, indicating a single circular chromosome; however, strain AU13965 also carried a plasmid of 42,977 bp, the first described in the genus Herbaspirillum. Genome comparison revealed that the clinical strains lost the gene sets related to biological nitrogen fixation (nif) and the type 3 secretion system (T3SS), which has been described to be essential for interactions with plants. Comparison of the pan-genomes of clinical and environmental strains revealed different sets of accessorial genes. However, antimicrobial resistance genes were found in the same proportion in all analyzed genomes. The clinical strains also acquired new genes and genomic islands that may be related to host interactions. Among the acquired islands was a cluster of genes related to lipopolysaccharide (LPS) biosynthesis. Although highly conserved in environmental strains, the LPS biosynthesis genes in the two clinical strains presented unique and non-orthologous genes within the genus Herbaspirillum. Furthermore, the AU14040 strain cluster contained the neuABC genes, which are responsible for sialic acid (Neu5Ac) biosynthesis, indicating that this bacterium could add it to its lipopolysaccharide. The Neu5Ac-linked LPS could increase the bacterial resilience in the host aiding in the evasion of the immune system.

CONCLUSIONS

Our findings suggest that the lifestyle transition from environment to opportunist led to the loss and acquisition of specific genes allowing adaptations to colonize and survive in new hosts. It is possible that these substitutions may be the starting point for interactions with new hosts.

Severe Community-Acquired Pneumonia with Bacteremia Caused by Herbaspirillum aquaticum or Herbaspirillum huttiense in an Immune-Competent Adult

Herbaspirillum spp. are Gram-negative bacteria that inhabit soil and water. Infections caused by these organisms have been reported in immunocompromised hosts. We describe severe community-acquired pneumonia and bacteremia caused by Herbaspirillum aquaticum or H. huttiense in an immunocompetent adult male.

Fatal case of Herbaspirillum seropedicae bacteremia secondary to pneumonia in an end-stage renal disease patient with multiple myeloma

Herbaspirillum spp. are rare causes of human infections associated primarily with bacteremia in cancer patients. We report the first fatal case of bacteremia secondary to pneumonia caused by Herbaspirillum seropedicae in a 65-year-old man with end-stage renal disease and multiple myeloma.