Case report: infective endocarditis caused by Brevundimonas vesicularis

Brevundimonas brasiliensis sp. nov.: a New Multidrug-Resistant Species Isolated from a Patient in Brazil

To increase knowledge on Brevundimonas pathogens, we conducted in-depth genomic and phenotypic characterization of a Brevundimonas strain isolated from the cerebrospinal fluid of a patient admitted in a neonatal intensive care unit. The strain was identified as a member of the genus Brevundimonas based on Vitek 2 system results and 16S rRNA gene sequencing and presented a multidrug resistance profile (MDR). Several molecular and biochemical tests were used to characterize and identify the species for in-depth results. The draft genome assembly of the isolate has a total length of 3,261,074 bp and a G+C of 66.86%, similar to other species of the genus. Multilocus sequence analysis, Type (Strain) Genome Server, digital DNA-DNA hybridization, and average nucleotide identity confirmed that the Brevundimonas sp. studied represents a distinct species, for which we propose the name Brevundimonas brasiliensis sp. nov. In silico analysis detected antimicrobial resistance genes (AMRGs) mediating resistance to β-lactams (penP, blaTEM-16, and blaBKC-1) and aminoglycosides [strA, strB, aac(6')-Ib, and aac(6')-Il]. We also found AMRGs encoding the AcrAB efflux pump that confers resistance to a broad spectrum of antibiotics. Colistin and quinolone resistance can be attributed to mutation in qseC and/or phoP and GyrA/GyrB, respectively. The Brevundimonas brasiliensis sp. nov. genome contained copies of type IV secretion system (T4SS)-type integrative and conjugative elements (ICEs); integrative mobilizable elements (IME); and Tn3-type and IS3, IS6, IS5, and IS1380 families, suggesting an important role in the development and dissemination of antibiotic resistance. The isolate presented a range of virulence-associated genes related to biofilm formation, adhesion, and invasion that can be relevant for its pathogenicity. Our findings provide a wealth of data to hinder the transmission of MDR Brevundimonas and highlight the need for monitoring and identifying new bacterial species in hospital environments. IMPORTANCE Brevundimonas species is considered an opportunistic human pathogen that can cause multiple types of invasive and severe infections in patients with underlying pathologies. Treatment of these pathogens has become a major challenge because many isolates are resistant to most antibiotics used in clinical practice. Furthermore, there are no consistent therapeutic results demonstrating the efficacy of antibacterial agents. Although considered a rare pathogen, recent studies have provided evidence of the emergence of Brevundimonas in clinical settings. Hence, we identified a novel pathogenic bacterium, Brevundimonas brasiliensis sp. nov., that presented a multidrug resistance (MDR) profile and carried diverse genes related to drug resistance, virulence, and mobile genetic elements. Such data can serve as a baseline for understanding the genomic diversity, adaptation, evolution, and pathogenicity of MDR Brevundimonas.

Comparative Genomic Analysis Reveals Potential Pathogenicity and Slow-Growth Characteristics of Genus Brevundimonas and Description of Brevundimonas pishanensis sp. nov

The genus Brevundimonas consists of Gram-negative bacteria widely distributed in environment and can cause human infections. However, the genomic characteristics and pathogenicity of Brevundimonas remain poorly studied. Here, the whole-genome features of 24 Brevundimonas type strains were described. Brevundimonas spp. had relatively small genomes (3.13 ± 0.29 Mb) within the family Caulobacteraceae but high G+C contents (67.01 ± 2.19 mol%). Two-dimensional hierarchical clustering divided those genomes into 5 major clades, in which clades II and V contained nine and five species, respectively. Interestingly, phylogenetic analysis showed a one-to-one match between core and accessory genomes, which suggested coevolution of species within the genus Brevundimonas. The unique genes were annotated to biological functions like catalytic activity, signaling and cellular processes, multisubstance metabolism, etc. The majority of Brevundimonas spp. harbored virulence-associated genes icl, tufA, kdsA, htpB, and acpXL, which encoded isocitrate lyase, elongation factor, 2-dehydro-3-deoxyphosphooctonate aldolase, heat shock protein, and acyl carrier protein, respectively. In addition, genomic islands (GIs) and phages/prophages were identified within the Brevundimonas genus. Importantly, a novel Brevundimonas species was identified from the feces of a patient (suffering from diarrhea) by the analyses of biochemical characteristics, phylogenetic tree of 16S rRNA gene, multilocus sequence analysis (MLSA) sequences, and genomic data. The name Brevundimonas pishanensis sp. nov. was proposed, with type strain CHPC 1.3453 (= GDMCC 1.2503^T= KCTC 82824^T). Brevundimonas spp. also showed obvious slow growth compared with that of Escherichia coli. Our study reveals insights into genomic characteristics and potential virulence-associated genes of Brevundimonas spp., and provides a basis for further intensive study of the pathogenicity of Brevundimonas.

IMPORTANCEBrevundimonas spp., a group of bacteria from the family Caulobacteraceae, is associated with nosocomial infections, deserve widespread attention. Our study elucidated genes potentially associated with the pathogenicity of the Brevundimonas genus. We also described some new characteristics of Brevundimonas spp., such as small chromosome size, high G+C content, and slow-growth phenotypes, which made the Brevundimonas genus a good model organism for in-depth studies of growth rate traits. Apart from the comparative analysis of the genomic features of the Brevundimonas genus, we also reported a novel Brevundimonas species, Brevundimonas pishanensis, from the feces of a patient with diarrhea. Our study promotes the understanding of the pathogenicity characteristics of Brevundimonas species bacteria.

Brevundimonas spp: Emerging global opportunistic pathogens

Non-fermenting Gram-negative bacteria are problematic in clinical locations, being one of the most prevalent causes of nosocomial infections. Many of these non-fermenting Gram-negative bacteria are opportunistic pathogens that affect patients that are suffering with underlying medical conditions and diseases. Brevundimonas spp., in particular Brevundimonas diminuta and Brevundimonas vesicularis, are a genus of non-fermenting Gram-negative bacteria considered of minor clinical importance. Forty-nine separate instances of infection relating to Brevundimonas spp were found in the scientific literature along with two pseudo-infections. The majority of these instances were infection with Brevundimonas vesicularis (thirty-five cases – 71%). The major condition associated with Brevundimonas spp infection was bacteraemia with seventeen individual cases/outbreaks (35%). This review identified forty-nine examples of Brevundimonas spp. infections have been discussed in the literature. These findings indicate that infection review programs should consider investigation of possible Brevundimonas spp outbreaks if these bacteria are clinically isolated in more than one patient.

Fibrinous pericarditis secondary to bacterial infection in a cat

A three-year-old spayed domestic short-haired cat presented for evaluation of weight loss, cardiomegaly and pleural effusion. Echocardiographic examination demonstrated a thickened pericardium with mild pericardial effusion and a large volume of pleural effusion characterized by exudate. Although the cat was treated with antibiotics, the clinical symptoms did not improve. The cat developed dyspnea and died on day 7. Necropsy revealed a large amount of modified transudates ascites, pleural effusion and markedly dilated pericardium. Histopathological examination revealed severe exudation of fibrin and granulation tissue in a thick layer of the epicardium. The cat was diagnosed with fibrinous pericarditis secondary to bacterial infection.

Potential Infection Control Risks Associated with Ultrasound Equipment - A Bacterial Perspective

Ultrasound equipment used in trans-abdominal (TA) and trans-vaginal (TV) examination may carry bacterial contamination and pose risks to infection control during ultrasound examination. We aimed to describe the prevalence of bacterial contamination on ultrasound probes, gel, machine keyboard and cords and examined the effectiveness of low- and high-level disinfection techniques. This study was performed at a public hospital and a private practice. A total of 171 swabs were analyzed and bacterial species were identified using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) analysis and polymerase chain reaction (PCR). Sixty percent of TA probes and 14% of TV probes had evidence of bacterial contamination after an ultrasound examination. Low-level disinfection was partially effective, but 4% of probes were still contaminated by spore-forming species. Some heated gel samples were highly contaminated with the environmental bacterium Brevundimonas aurantiaca, suggesting the gel was conducive to bacterial growth. Ultrasound machines, probe cords and gels were identified as potential sources of bacterial contamination and need to be cleaned and changed regularly to minimize risks of infection.

A premature neonate with early-onset neonatal sepsis owing to Brevundimonas vesicularis complicated by persistent meningitis and lymphadenopathy

Human infection by Brevundimonas vesicularis is very rare, especially in children. A 29-week-old neonate is reported who developed early neonatal sepsis owing to B. vesicularis complicated by persistent meningitis and lymphadenopathy. B. vesicularis may be an emerging pathogen in neonatal infection.

Liver abscess caused by Brevundimonas vesicularis in an immunocompetent patient

Invasive infections caused by Brevundimonas vesicularis are very rare in humans. We experienced an unusual case of liver abscess due to B. vesicularis in an immunocompetent young male. The patient was successfully treated by liver abscess drainage and with antimicrobial therapy of ceftriaxone followed by ampicillin/sulbactam. The organism found in the aspiration culture of the abscess material was initially reported, by using a VITEK 2 system, as Sphingomonas paucimobilis. However, later, B. vesicularis was confirmed as the true pathogen through 16S rRNA gene sequencing. To our knowledge, this is the first case of liver abscess caused by B. vesicularis.

Spectrum of Brevundimonas vesicularis infections in neonatal period: a case series at a tertiary referral center

OBJECTIVES

To report infections caused by Brevundimonas vesicularis and the treatment regimens administered based on antibiotic studies of this Gram-negative bacterium in the neonatal period.

PATIENTS AND METHODS

Eight hospitalized neonates with positive blood cultures for Brevundimonas spp. were studied. Demographic data, clinical and laboratory findings, nutritional regimens, presence of primary disease, and the antibiotic regimens administered during the treatment of these neonates were noted. Antimicrobial susceptibility tests were performed on isolates of the positive cultures.

RESULT

Four neonates were preterm, and four were full-term infants. The underlying diseases--with the exception of being a neonate--were congenital heart disease (4 patients), respiratory distress syndrome (2), multiple congenital cerebral anomalies (1), and meconium aspiration syndrome (1). Septicemia was observed in all eight patients, while three also had concurrent meningitis. Multidrug resistance to the antimicrobials, including piperacillin-tazobactam, ceftazidime, and aztreonam, were identified in all eight infants; however, susceptibility to amikacin and imipenem was retained. All study patients responded to the antibiotic treatments and subsequent cultures were sterile. One patient died due to other causes.

CONCLUSIONS

We consider that until larger series are available, B. vesicularis should be regarded as virulent. Consequently, in this era of multi-resistant Gram-negative bacteria, serious B. vesicularis infections in neonates should be treated with a broad-spectrum agent, such as third-generation cephalosporin until the results of susceptibility testing are available. Our case reports demonstrate that the susceptibility of this organism to all aminoglycosides and third-generation cephalosporin is not uniform, but that most of the isolates are susceptible to imipenem. More treatment experience and more exact results from antimicrobial susceptibility testing are required to improve on present treatment regimens for invasive B. vesicularis infections.

A Cutaneous Infection Caused by Brevundimonas Vesicularis: A Case Report

Brevundimonas vesicularis is a non-fermenting gram-negative bacillus, aerobic and motile. This microrganism is ubiquitous in the environment and has rarely been implicated in human infections. We present the second case of cutaneous infection caused by B. vesicularis in an immunocompetent patient.