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

Inflammation-oriented montmorillonite adjuvant enhanced oral delivery of anti-TNF-α nanobody against inflammatory bowel disease

Oral delivery of proteins faces challenges due to the harsh conditions of the gastrointestinal (GI) tract, including gastric acid and intestinal enzyme degradation. Permeation enhancers are limited in their ability to deliver proteins with high molecular weight and can potentially cause toxicity by opening tight junctions. To overcome these challenges, we propose the use of montmorillonite (MMT) as an adjuvant that possesses both inflammation-oriented abilities and the ability to regulate gut microbiota. This adjuvant can be used as a universal protein oral delivery technology by fusing with advantageous binding amino acid sequences. We demonstrated that anti-TNF-α nanobody (VII) can be intercalated into the MMT interlayer space. The carboxylate groups (-COOH) of aspartic acid (D) and glutamic acid (E) interact with the MMT surface through electrostatic interactions with sodium ions (Na+). The amino groups (NH2) of asparagine (N) and glutamine (Q) are primarily attracted to the MMT layers through hydrogen bonding with oxygen atoms on the surface. This binding mechanism protects VII from degradation and ensures its release in the intestinal tract, as well as retaining biological activity, leading to significantly enhanced therapeutic effects on colitis. Furthermore, VII@MMT increases the abundance of short-chain fatty acids (SCFAs)-producing strains, including Clostridia, Prevotellaceae, Alloprevotella, Oscillospiraceae, Clostridia_vadinBB60_group, and Ruminococcaceae, therefore enhance the production of SCFAs and butyrate, inducing regulatory T cells (Tregs) production to modulate local and systemic immune homeostasis. Overall, the MMT adjuvant provides a promising universal strategy for protein oral delivery by rational designed protein.

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.

Bacterial dynamics of the plastisphere microbiome exposed to sub-lethal antibiotic pollution

BACKGROUND

Antibiotics and microplastics are two major aquatic pollutants that have been associated to antibiotic resistance selection in the environment and are considered a risk to human health. However, little is known about the interaction of these pollutants at environmental concentrations and the response of the microbial communities in the plastisphere to sub-lethal antibiotic pollution. Here, we describe the bacterial dynamics underlying this response in surface water bacteria at the community, resistome and mobilome level using a combination of methods (next-generation sequencing and qPCR), sequencing targets (16S rRNA gene, pre-clinical and clinical class 1 integron cassettes and metagenomes), technologies (short and long read sequencing), and assembly approaches (non-assembled reads, genome assembly, bacteriophage and plasmid assembly).

RESULTS

Our results show a shift in the microbial community response to antibiotics in the plastisphere microbiome compared to surface water communities and describe the bacterial subpopulations that respond differently to antibiotic and microplastic pollution. The plastisphere showed an increased tolerance to antibiotics and selected different antibiotic resistance bacteria (ARB) and antibiotic resistance genes (ARGs). Several metagenome assembled genomes (MAGs) derived from the antibiotic-exposed plastisphere contained ARGs, virulence factors, and genes involved in plasmid conjugation. These include Comamonas, Chryseobacterium, the opportunistic pathogen Stenotrophomonas maltophilia, and other MAGs belonging to genera that have been associated to human infections, such as Achromobacter. The abundance of the integron-associated ciprofloxacin resistance gene aac(6')-Ib-cr increased under ciprofloxacin exposure in both freshwater microbial communities and in the plastisphere. Regarding the antibiotic mobilome, although no significant changes in ARG load in class 1 integrons and plasmids were observed in polluted samples, we identified three ARG-containing viral contigs that were integrated into MAGs as prophages.

CONCLUSIONS

This study illustrates how the selective nature of the plastisphere influences bacterial response to antibiotics at sub-lethal selective pressure. The microbial changes identified here help define the selective role of the plastisphere and its impact on the maintenance of environmental antibiotic resistance in combination with other anthropogenic pollutants. This research highlights the need to evaluate the impact of aquatic pollutants in environmental microbial communities using complex scenarios with combined stresses. Video Abstract.

Tumor-associated microbiota in colorectal cancer with vascular tumor thrombus and neural invasion and association with clinical prognosis

Neural invasion (NI) and vascular tumor thrombus (VT) are associated with poor prognosis in patients with colorectal cancer (CRC). In this study, we apply 16S rRNA amplicon sequencing to tumor tissues and adjacent normal tissues in patients with CRC to determine the microbial differences. A discovery cohort, including 30 patients with NI, 23 with VT, and 35 with double-negative CRC tissue, is utilized. Then, we analyze the relationship between the specific bacterial taxa and indicators of different dimensions in separate cohorts. In the discovery cohort, the diversity and composition of the gut microbiome distinctly differ between the tumor and nontumor tissues in the NI and VT groups. A high abundance of Cupriavidus is found to be related to a short survival time of NI CRC, while Herbaspirillum is a potential microbial biomarker predicting the prognosis of patients with CRC with NI or VT. Moreover, the abundance of Cupriavidus or Herbaspirillum is associated with some clinical patient characteristics and prognosis, respectively. In conclusion, this study is the first to comprehensively elaborate the differences in the gut microbiota of patients with CRC with different invasion statuses and to prove the relationship between some gut microbiota and clinical patient characteristics.

Septic Shock and Bacteremia Secondary to Herbaspirillum huttiense: A Case Report and Review of Literature

The Herbaspirillum species are gram-negative bacteria that inhabit soil and water. Infections caused by this pathogen are an uncommon clinical entity. We describe a rare case of septic shock and bacteremia caused by Herbaspirillum huttiense in an immunocompetent adult female. The patient, a 59-year-old female, presented to the hospital with circulatory shock, fever, chills, and cough. Chest x-ray revealed right lower lobe lung consolidation consistent with pneumonia, and blood cultures with a positive concerning gram-negative curved rod which was later identified as H. huttiense. The patient was treated in the ICU for three days with cefepime and vasoactive agents. After improvement and an additional seven days of hospitalization, the patient was discharged home with a five-day course of oral levofloxacin. Although our patient responded well to cefepime and levofloxacin, meropenem and piperacillin-tazobactam were found to be the most commonly used and the most effective antibiotics to treat H. huttiense infections in other reported cases. This is amongst the few reported cases of H. huttiense bacteremia in an immunocompetent individual with pneumonia.

Fecal microbiota transplantation attenuates Escherichia coli infected outgrowth by modulating the intestinal microbiome

BACKGROUND

Given the crucial role of gut microbiota in animal and human health, studies on modulating the intestinal microbiome for therapeutic purposes have grasped a significant attention, of which the role of fecal microbiota transplantation (FMT) has been emphasized.

METHODS

In the current study, we evaluated the effect of FMT on gut functions in Escherichia coli (E. coli) infection by using mice model. Moreover, we also investigated the subsequently dependent variables of infection, i.e., body weight, mortality, intestinal histopathology, and the expression changes in tight junction proteins (TJPs).

RESULTS

The FMT effectively decreased weight loss and mortality to a certain extent with the restoration of intestinal villi that resulted in high histological scores for jejunum tissue damage (p < 0.05). The effect of FMT on alleviating the reduction of intestinal TJPs was also proved by immunohistochemistry analysis and mRNA expression levels. Moreover, the abundance of health-threatening bacteria, belonging to phylum Proteobacteria, family Enterobacteriaceae and Tannerellaceae, genus Escherichia-Shigella, Sphingomonas, Collinsella, etc., were significantly increased, whereas beneficial bacteria, belonging to phylum Firmicutes, family Lactobacillaceae, genus Lactobacillus were decreased in the gut of infected mice. Furthermore, we sought to investigate the association of clinical symptoms with FMT treatment with modulation in gut microbiota. According to beta diversity, the microbial community of gut microbiota results reflected the similarities between non-infected and FMT groups. The improvement of the intestinal microbiota in FMT group was characterized by the significant high level of beneficial microorganisms with the synergistic decrease of Escherichia-Shigella, Acinetobacter, and other taxa.

CONCLUSION

The findings suggest a beneficial host-microbiome correlation following fecal microbiota transplanatation for controlling gut infections and pathogens-associated diseases.

A Correlation Study of the Microbiota Between Oral Cavity and Tonsils in Children With Tonsillar Hypertrophy

Tonsillar hypertrophy is a common disease in 3-to-6-year-old children, which may cause serve symptoms like airway obstruction. Microbiological factors play an important role in the etiology of tonsillar hypertrophy. As the starting point of digestive and respiratory tracts, the microbial composition of the oral cavity is not only unique but also closely related to the resident microbiota in other body sites. Here we reported a correlation study of the microbiota between oral cavity and tonsils in children with tonsillar hypertrophy. Saliva, supragingival plaque, and wiped samples from the tonsil surface were collected from both tonsillar hypertrophy patients and participants with healthy tonsils and were then analyzed using Illumina Miseq Sequencing of the 16S rRNA gene. In the tonsillar hypertrophic state, more genera were detected on the tonsil surface than in the tonsil parenchyma, with more intra-microbiota correlations. When tonsillar hypertrophy occurred, both the oral cavity and tonsil surface endured microbiome shift with increased genera category and more active bacterial interactions. Over half of the newly detected genera from the tonsillar hypertrophic state were associated with infection and inflammation process or exhibited antibiotic-resistant characters. Of each individual, the microbial composition and structure of saliva seemed more similar to that of the tonsil surface, compared with the supragingival plaque. In salivary microbiota, genus Johnsonella might be relative with the healthy state of tonsils, while Pseudoxanthomonas might be relative with tonsillar hypertrophy. Our study supported the link between oral microbiota with the healthy and hypertrophic states of tonsils and may provide new directions for future researches in the specific role of oral microbiota in the etiology of tonsil diseases.

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.