Clinical correlation and antimicrobial susceptibility pattern of Chryseobacterium spp.: A three year prospective study

Current viewpoint on the epidemiology of nonfermenting Gram-negative bacterial strains

PURPOSE OF REVIEW

This article aims to review the epidemiology of nonfermenting Gram-negative bacilli (NFGNB) based on recent literature reports, particularly, of the less common, but with emerging clinical significance species.

RECENT FINDINGS

The reported frequency of multidrug-resistant Acinetobacter baumannii and Pseudomonas aeruginosa is increasing, with very significant variability, however, between different countries. Apart from the major NFGNB, that is, A. baumannii and P. aeruginosa, already recognized as of critical importance healthcare risks, several other NFGNB genera have been increasingly associated with diverse severe infections, such as Stenotrophomonas maltophilia, Burkholderia spp., Elizabethkingia spp., Chryseobacterium spp., Achromobacter spp., Alcaligenes spp., Sphingomonas spp., Shewanella spp. and Ralstonia spp., among others.

SUMMARY

The exploration of the epidemiology, as well as the pathogenic potential of the of the less frequent, but emerging and increasingly reported NFGNB, is crucial, not only for immunocompromised patients, but also for critically ill patients without overt immunosuppression. As we are heading fast towards a postantibiotic era, such information would contribute to the optimal antimicrobial management, that is, providing prompt, appropriate antimicrobial coverage when needed and, at the same time, avoiding overuse and/or inappropriate use of antimicrobial therapy. Also, it would help to better understand their transmission dynamics and to develop effective prevention strategies.

Chryseobacterium luquanense sp. nov., a casein-hydrolysing bacterium from the Jiaozi Mountain in Yunnan, PR China

Strain KC 927T was isolated during an investigation of the soil bacteria diversity on Jiaozi Mountain, central Yunnan, Southwest China. The strain was Gram-stain-negative, rod-shaped, non-motile, oxidase-negative, catalase-positive and aerobic. Results of 16S rRNA gene alignment and phylogenetic analysis indicated that strain KC 927T was a member of the genus Chryseobacterium and closely related to Chryseobacterium caseinilyticum GCR10T (98.4%), Chryseobacterium piscicola DSM 21068T (98.3 %) and 'Chryseobacterium formosus' CCTCC AB 2015118T (97.9 %). With a genome size of 4 348 708 bp, strain KC 927T had 33.5 mol% DNA G+C content and contained 4012 protein-coding genes and 77 RNA genes. The average nucleotide identity and digital DNA-DNA hybridization values between strain KC 927T and C. caseinilyticum GCR10T, C. piscicola DSM 21068T and 'C. formosus' CCTCC AB 2015118T were 80.1, 79.6 and 90.7 %, and 25.5, 23.6 and 42.0 %, respectively. The main polar lipid of strain KC 927T was phosphatidylethanolamine and the respiratory quinone was MK-6. The major fatty acids (≥10 %) were iso-C15 : 0, iso-C17 : 1  ω9c and iso-C17 : 0 3-OH. Evidence from phenotypic, phylogenetic and chemotaxonomic analyses support that strain KC 927T represents a new species of the genus Chryseobacterium, for which the name Chryseobacterium luquanense sp. nov. is proposed. The type strain is KC 927T (=CGMCC 1.18760T=JCM 35707T).

Blood Stream Infection Caused by Carbapenem-resistant Chryseobacterium indologenes Harboring blaNDM-1 Gene Isolated from a Tertiary Care Hospital in Tripura: An Emerging Threat

OBJECTIVES

Chryseobacterium indologenes has recently been identified as an inherently drug-resistant organism, responsible for a wide spectrum of infections, mainly device-associated infections in hospital settings. The presence of carbapenem resistance due to blaNDM-1 metallo-β-lactamase (MBL) gene further complicates the matter, leading to widespread dissemination of carbapenem resistance. This study aims to find out the presence of blaNDM-1 gene among C. indologenes strains causing bloodstream infections in a tertiary care hospital.

MATERIALS AND METHODS

During 1 year of the study period, blood culture samples were collected from patients with features of bacteremia, and C. indologenes strains were isolated and identified as per protocol. Antibiotic sensitivity test was performed by using VITEK 2 Compact Automated AST machine (Biomerieux, France). Carbapenem-resistant strains were subjected to a combined disk diffusion test for detecting the presence of MBL enzyme. Strains positive for MBL production were subjected to a polymerase chain reaction (PCR) for detection of blaNDM-1 gene.

RESULTS

Out of 21 strains isolated during the study period, 12 strains (57.1%) were carbapenem-resistant. Among them, seven strains (58.3%) were MBL producers. After PCR, 3 strains (42.9%) were found to be harboring blaNDM-1 gene Discussion: As per our knowledge, this is the first report of blaNDM-1 gene harboring C. indologenes strain from Northeast India. This shows the emerging therapeutic dilemma due to the narrowing of treatment options against bloodstream infections due to C. indologenes strains. Strict antimicrobial stewardship has to be implemented to prevent the further compounding of the problem.

Emerging Bacterial Pathogens in the COVID-19 Era: Chryseobacterium gleum—A Case in Point

Introduction In the ongoing severe acute respiratory syndrome coronavirus 2 pandemic, a long hospital stay and empirical broad-spectrum antibiotics make the patients prone to acquire nosocomial infections especially with unconventional organisms, and Chryseobacterium gleum is one such rare nosocomial pathogen.

Methods The given study is a case-series-based study conducted from September 2020 to April 2021 in which clinically suspected pneumonia patients who recovered from coronavirus disease 2019 (COVID-19) were included.

Results Seventeen C. gleum isolates were obtained in pure culture from the tracheal aspirates of nine COVID-19 patients (including repeat samples to rule out colonization) within a period of eight months (September 2020–April 2021). Our records showed that there has been an increase in the number of isolates of C. gleum obtained in respiratory samples in 2020. We also did a review of literature of all the cases of C. gleum pneumonia reported till now.

Conclusion To the best of our knowledge, this is the first study reporting the isolation of this rare pathogen from COVID-19 patients with clinical significance in a large cohort of patients. Therefore, it becomes important to consider this pathogen as a significant cause of respiratory infections, especially in patients recovered post COVID-19.

Identification and Biosynthesis of Pro-Inflammatory Sulfonolipids from an Opportunistic Pathogen Chryseobacterium gleum

Sulfonolipids (SoLs) are a unique class of sphingolipids featuring a sulfonate group compared to other sphingolipids. However, the biological functions and biosynthesis of SoLs in human microbiota have been poorly understood. Here, we report the discovery and isolation of SoLs from a human opportunistic pathogen Chryseobacterium gleum DSM16776. We show for the first time the pro-inflammatory activity of SoLs with mice primary macrophages. Furthermore, we used both in vivo heterologous expression and in vitro biochemical reconstitution to characterize two enzymes, cysteate synthase and cysteate fatty acyltransferase, that are specifically involved in the biosynthesis of SoLs rather than other sphingolipids. Based on these two SoL-specific enzymes, our bioinformatics analysis showed a wider distribution of SoL biosynthetic genes in microbes that had not been reported as SoL producers. We selected four of these strains and verified their cysteate synthase and cysteate fatty acyltransferase activities in SoL biosynthesis. Considering this wider distribution of SoL-specific biosynthetic enzymes in the context of SoLs' activity in mediating inflammation, a common and fundamental biological process, it may suggest a more comprehensive function of SoLs at play.