Microbiological characterization of Delftia acidovorans clinical isolates from patients in an intensive care unit in Brazil

Impact of Species and Developmental Stage on the Bacterial Communities of Aphaenogaster Ants

Ants are distributed across the globe and there are currently over 14,000 described species. Due to the high diversity between species, ants are considered vital keystone species to many ecosystems. They provide basic ecosystem services such as: seed dispersal, soil bioturbation, decomposition, and pest control. Within these ecosystems ants form complex symbiotic relationships with plants, fungi, and bacteria. Studying the interaction between ants and their bacteria is important because of the crucial role that microbes play in the overall health of ants. Aphaenogaster Mayr, 1853, which is a globally distributed ant genus, remains understudied in terms of their bacterial community. This study aims to determine the taxonomic composition and abundance of the Aphaenogaster bacterial community and to determine if development stage and species impact the bacterial community composition. For this study, ants from several colonies were collected from the Gordon Natural Area in West Chester, Pennsylvania, USA. DNA was then extracted from the ants in all stages of development and the 16S rRNA gene was amplified and sequencing following the NGS amplicon approach. The findings from this study reveal that species and development stage have a significant impact upon the bacterial community composition and abundance of Aphaenogaster ants, and Wolbachia is highly associated with these ants.

Influence of growth medium on the species-specific interactions between algae and bacteria

In this study, we investigated a species-specific algal-bacterial co-culture that has recently attracted worldwide scientific attention as a novel approach to enhancing algal growth rate. We report that the type of interaction between Chlorella vulgaris and bacteria of the genus Delftia is not solely determined by species specificity. Rather, it is a dynamic process of adaptation to the surrounding conditions, where one or the other microorganism dominates (temporally) depending on the growth conditions, in particular the medium. Under laboratory conditions, we found that Delftia sp. had a negative effect on C. vulgaris growth when co-cultured in a TAP medium. However, the co-culture of algae and bacteria under BG-11 and BG-11 + acetic acid resulted in an increase in algal concentration compared to algal cultures without bacteria under the same conditions. Additional chemical analysis revealed that the presence of different carbon (the main organic carbon source-acetic acid in TAP or BG-11 + acetic acid medium and inorganic carbon source-Na2CO3 in BG-11 or BG-11 + acetic acid medium) and nitrogen (NH4Cl in TAP medium and NaNO3 in BG-11 or BG-11 + acetic acid medium) species in the growth medium was one of the main factors driving the shift in interaction type.

Retrospective Cohort Study on Delftia acidovorans Infections in Patients: A Rare and Significant Infection

Background

In recent years, Delftia acidovorans has gained attention for its rare occurrence in patient infections. The literature consists mostly of case reports, necessitating further research to comprehensively understand risk factors, clinical characteristics, and management strategies.

Methods

We conducted a retrospective cohort study involving patients diagnosed with Delftia acidovorans infection at a tertiary teaching hospital between January 2014 and December 2022. The data included demographic details, comorbidities, bacterial cultures, antibiotic susceptibility, and treatment outcomes.

Results

There were 26 patients diagnosed with Delftia acidovorans infection who were predominantly older with multiple comorbidities. Approximately 76.9% of Delftia acidovorans infection patients had polymicrobial infections. Twenty-one patients had received antibiotics within three months before they developed the Delftia acidovorans infection, and these antibiotics were primarily third-generation cephalosporins, glycopeptides and fluoroquinolones. Antibiotic susceptibility testing showed resistance to aminoglycosides and susceptibility to imipenem, meropenem, ceftazidime, and piperacillin/tazobactam. Treatment outcome showed a mortality rate of 11.5%, mainly in patients with malignancy and advanced age.

Conclusion

Delftia acidovorans infections predominantly affect older patients with multiple comorbidities. In terms of antibiotic therapy, carbapenems, cephalosporins, and piperacillin/tazobactam with antipseudomonal activity could all be considered.

Characteristics and Outcomes of Patients with Delftia acidovorans Infections: a Retrospective Cohort Study

Delftia acidovorans (D. acidovorans) is a Gram-negative bacteria and an uncommon cause of human infections. This retrospective cohort study investigated clinical and microbiological characteristics and outcomes of patients with D. acidovorans infections. We included patients with culture-confirmed D. acidovorans infections attending Rigshospitalet, during 2002-2020. Fifty-nine patients with a median interquartile ranges (IQR) age of 47 (15-67) years were included. Thirty-five (59%) were males, and 57 (97%) had at least one comorbidity, including 25 (42%) with solid or hematologic malignancies. Eight (14%) were admitted to ICU, and 15 (25%) died within 365 days after infection. Persistent infection was found in 4 (6.8%) patients, and 41 (70%) had polymicrobial cultures, mainly with Pseudomonas spp. and Stenotrophomonas maltophilia. More than 85% of the D. acidovorans isolates were susceptible to meropenem or ceftazidime. Although, 88% and 62% of the isolates were resistant to gentamicin and colistin, respectively. D. acidovorans infections mainly affect patients with preexisting comorbidities, including malignancies. In the first year, all-cause mortality is considerable, polymicrobial cultures are common, and meropenem or cephalosporins with antipseudomonal activity could be the antibiotics of choice.

IMPORTANCEDelftia acidovorans (D. acidovorans) is a Gram-negative bacteria that can cause infection in immunocompetent and immunocompromised individuals. The current knowledge comes mainly from case reports and case series. In this retrospective cohort study, we found that D. acidovorans infections mainly affect male patients with preexisting comorbidities, including malignancies. Persistent infections were not common, and most of the patients had polymicrobial cultures, mainly with Pseudomonas spp. and Stenotrophomonas maltophilia. More than 85% of the D. acidovorans isolates were susceptible to meropenem or ceftazidime. In contrast, 88% and 62% of the isolates were resistant to gentamicin and colistin, respectively.

Culturomics revealed the bacterial constituents of the microbiota of a 10-year-old laboratory culture of planarian species S. mediterranea

The planarian species Schmidtea mediterranea is a flatworm living in freshwater that is used in the research laboratory as a model to study developmental and regeneration mechanisms, as well as antibacterial mechanisms. However, the cultivable microbial repertoire of the microbes comprising its microbiota remains unknown. Here, we characterized the bacterial constituents of a 10-year-old laboratory culture of planarian species S. mediterranea via culturomics analysis. We isolated 40 cultivable bacterial species, including 1 unidentifiable species. The predominant phylum is Proteobacteria, and the most common genus is Pseudomonas. We discovered that parts of the bacterial flora of the planarian S. mediterranea can be classified as fish pathogens and opportunistic human pathogens.

A New Type of Chronic Wound Infection after Wisdom Tooth Extraction: A Diagnostic Approach with 16S-rRNA Gene Analysis, Next-Generation Sequencing, and Bioinformatics

Delayed-onset infections are rare postoperative complications of lower third molar extractions. This article presents a case of a chronic combined hard and soft tissue infection after the extraction of a third molar, where the causative organisms could only be elucidated by molecular methods. Experimental 16S-rRNA gene analysis with next-generation sequencing and bioinformatics was used to identify the bacterial spectrum of the infection. 16S-rRNA gene analysis delivered the microbiome of the abscessing inflammation while standard culture and laboratory examinations were all sterile. The microbiome showed a mixed bacterial infection with a dominance of Delftia and Alcanivorax (spp.) besides other bacteria of the normal oral flora. Using 16S-rRNA-gene analysis, next-generation sequencing, and bioinformatics, a new type of chronic wound infection after wisdom tooth extraction was found. The property of Delftia and Alcanivorax (spp.) as water-affine environmental bacteria raises suspicion of infection from contaminated water from a dental unit. Thus, osteotomies of teeth should only be done with sterile cooling water. The 16S-rRNA gene analysis should become a part of the routine diagnostics in medical microbiology.

Delftia acidovorans: A rare pathogen in immunocompetent and immunocompromised patients

Delftia acidovorans is an aerobic, nonfermenting Gram-negative bacillus. It is usually a nonpathogenic environmental organism and is rarely clinically significant. Although D acidovorans infection most commonly occurs in hospitalized or immunocompromised patients, there are also several reports documenting the infection in immunocompetent patients. The present article describes a B cell lymphoblastic leukemia patient with D acidovorans pneumonia who was successfully treated with antibiotic therapy. The present report indicates that unusual pathogens may be clinically significant in both immunocompromised and immunocompetent patients. D acidovorans is often resistant to aminoglycosides; therefore, rapid detection of this microorganism is important.