&lt;p&gt;A case of persistent bacteraemia by &lt;em&gt;Ralstonia mannitolilytica&lt;/em&gt; and &lt;em&gt;Ralstonia pickettii&lt;/em&gt; in an intensive care unit&lt;/p&gt;

Liu

et al. 2020

Preprint

Little is known about the species and strain-level diversity of the airway microbiome, and its implication in chronic obstructive pulmonary disease (COPD).Here we report the first comprehensive analysis of the COPD airway microbiome at species and strain-levels. The full-length 16S rRNA gene was sequenced from sputum in 98 stable COPD patients and 27 age-matched healthy controls, using the ‘third-generation’ Pacific Biosciences sequencing platform.Individual species within the same genus exhibited reciprocal relationships with COPD and disease severity. Species dominant in health can be taken over by another species within the same genus in GOLD IV patients. Such turnover was also related to enhanced symptoms and exacerbation frequency. Ralstonia mannitolilytica, an opportunistic pathogen, was significantly increased in COPD frequent exacerbators. There were inflammatory phenotype-specific associations of microbiome at the species-level. One group of four pathogens including Haemophilus influenzae and Moraxella catarrhalis, were specifically associated with sputum mediators for neutrophilic inflammation. Another group of seven species, including Tropheryma whipplei, showed specific associations with mediators for eosinophilic inflammation. Strain-level detection uncovered three non-typeable H. influenzae strains PittEE, PittGG and 86-028NP in the airway microbiome, where PittGG and 86-028NP abundances may inversely predict eosinophilic inflammation. The full-length 16S data augmented the power of functional inference and led to the unique identification of butyrate-producing and nitrate reduction pathways as significantly depleted in COPD.Our analysis uncovered substantial intra-genus heterogeneity in the airway microbiome associated with inflammatory phenotypes and could be of clinical importance, thus enabled a refined view of the airway microbiome in COPD.“Take-home” messageThe species-level analysis using the ‘third-generation’ sequencing enabled a refined view of the airway microbiome and its relationship with clinical outcome and inflammatory phenotype in COPD.

Section: Discussionmentioning

confidence: 99%

A Refined View of Airway Microbiome in Chronic Obstructive Pulmonary Disease at Species and Strain-levels

Liu

et al. 2020

Preprint

Antimicrob Resist Infect Control

“…Tests for nitrate reduction (negative in R.mannitolilytica ) and acidification of D-arabitol and mannitol (both negative in R.pickettii ) can differentiate the 2 species [ 11 ]. Matrix assisted laser desorption and ionisation time of flight methods such as MALDI TOF MS (Biomerieux, France) has also been found to yield a more accurate species level identification of Ralstonia species [ 4 ]. 16S rRNA gene sequencing has proved very useful in the definitive identification of R.mannitolilytica , and is now considered the reference method for identification to species level [ 4 , 12 ].…”

Section: Discussionmentioning

confidence: 99%

“…Matrix assisted laser desorption and ionisation time of flight methods such as MALDI TOF MS (Biomerieux, France) has also been found to yield a more accurate species level identification of Ralstonia species [ 4 ]. 16S rRNA gene sequencing has proved very useful in the definitive identification of R.mannitolilytica , and is now considered the reference method for identification to species level [ 4 , 12 ]. We used the Vitek 2 instrument for identification and this may explain why Ralstonia picketii was identified from the water specimen as opposed to Ralstonia mannitolilytica from clinical specimens.…”

Section: Discussionmentioning

confidence: 99%

“…Ralstonia species are generally resistant to many of the β-lactam class of antibiotics, including the carbapenems. Class D carabapenmase genes such as bla OXA-22 and bla OXA-60 are commonly associated with Ralstonia species [ 4 ]. Treatment of Ralstonia infection is usually based on the susceptibility profile of the organism isolated [ 2 ].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Outbreak of Ralstonia mannitolilytica bacteraemia in patients undergoing haemodialysis at a tertiary hospital in Pretoria, South Africa

Said

Hougenhouck-Tulleken

Naidoo

et al. 2020

Background Ralstonia species are Gram-negative bacilli of low virulence. These organisms are capable of causing healthcare associated infections through contaminated solutions. In this study, we aimed to determine the source of Ralstonia mannitolilytica bacteraemia in affected patients in a haemodialysis unit. Methods Our laboratory noted an increase in cases of bacteraemia caused by Ralstonia mannitililytica between May and June 2016. All affected patients underwent haemodialysis at the haemodialysis unit of an academic hospital. The reverse osmosis filter of the haemodialysis water system was found to be dysfunctional. We collected water for culture at various points of the dialysis system to determine the source of the organism implicated. ERIC-PCR was used to determine relatedness of patient and environmental isolates. Results Sixteen patients were found to have Ralstonia mannitolilytica bacteraemia during the outbreak period. We cultured Ralstonia spp. from water collected in the dialysis system. This isolate and patient isolates were found to have the identical molecular banding pattern. Conclusions All patients were septic and received directed antibiotic therapy. There was 1 mortality. The source of the R. mannitolilytica infection in these patients was most likely the dialysis water as the identical organism was cultured from the dialysis water and the patients. The hospital management intervened and repaired the dialysis water system following which no further cases of R. mannitolilytca infections were detected. A multidisciplinary approach is required to control healthcare associated infections such as these. Routine maintenance of water systems in the hospital is essential to prevent clinical infections with R.mannitolilytica .

“…COPD patients present altered airway microbiome, with Ralstonia mannitolilytica identi ed in a signi cantly higher rate comparing with healthy population [4]. Despite its commonly overlooked role as a commensal, R. mannitolilytica becomes an emerging global opportunistic human pathogen and a causative agent of various infections and diseases, including bacteremia, meningitis, sepsis, peritonitis, osteomyelitis, hemoperitoneum and urinary tract infection [5][6][7][8][9][10]. Furthermore, R. mannitolilytica is also identi ed in respiratory illnesses such as cystic brosis and COPD, presumably as colonizer [11,12].…”

Section: Introductionmentioning

confidence: 99%

Transition of Ralstonia Mannitolilytica From Commensal to Pathogen During Hospitalization: A Catheter Related Bloodstream Infection (CRBSI) Case Caused by R. Mannitolilytica Colonized in The Respiratory Tract

Liu

Peters

Yang

et al. 2020

Preprint