Clinical significance of coryneform Gram-positive rods from blood identified by MALDI-TOF mass spectrometry and their susceptibility profiles – a retrospective chart review

Mushtaq, Ammara; Chen, Derrick J.; Strand, Gregory J.; Dylla, Brenda L.; Cole, Nicolynn; Mandrekar, Jayawant N.; Patel, Robin

doi:10.1016/j.diagmicrobio.2016.04.013

Cited by 9 publications

(16 citation statements)

References 18 publications

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“…The present study was performed to identify the role of diphtheroids as potential pathogens, and although we show that 82% of suspicious diphtheroid isolates did not meet criteria for true infection, the remaining 18% were clinically significant, warranting species-level reporting to treating clinicians. Our findings are consistent with a recent report of diphtheroids in blood identifying 56% of isolates as potential contaminants (13). To routinely identify potential pathogens, we recommend that all diphtheroid-like isolates that are predominant or pure in culture be identified to the species level via MALDI-TOF MS or 16S rRNA sequencing.…”

Section: Discussionsupporting

confidence: 89%

“…This often led to the utilization of steroids to dampen inflammation and a delay in appropriate antibiotics to treat C. kroppenstedtii mastitis, resulting in worse disease (11,12). MALDI-TOF MS has revolutionized many aspects of clinical microbiology, including routine species-level identification of suspicious diphtheroid isolates and the establishment of data sets for clinical research (13,14). The present study was performed to identify the role of diphtheroids as potential pathogens, and although we show that 82% of suspicious diphtheroid isolates did not meet criteria for true infection, the remaining 18% were clinically significant, warranting species-level reporting to treating clinicians.…”

Section: Discussionmentioning

confidence: 99%

“…Species-level identification can then be used to determine whether an isolate from a particular culture site should be reported to clinicians to the species level or as a diphtheroid. As recently shown by Patel et al, reporting of diphtheroid isolates to the species level influences treatment decisions (13), and it is imperative that the term "diphtheroid" be reserved solely for describing benign commensal flora isolated from sites at which the organism is not known to cause infection. In brief, the clinically relevant diphtheroids from our data set that warrant species-level reporting to the clinician after evaluation of clinical relevance using specimens from wounds include all Actinomyces species, C. kroppenstedtii, C. jeikeium, C. striatum, C. tuberculostearicum, P. acnes, and P. avidum.…”

Section: Discussionmentioning

confidence: 99%

“…Failure to accurately identify these organisms is a significant limitation of the present study, and future bioMérieux protein spectrum database updates should focus on resolving these ambiguities. In contrast, the Bruker system accurately identified C. amycolatum isolates from blood, most of which were deemed significant by treating clinicians (13). Meanwhile, if MALDI-TOF MS fails to identify a diphtheroid isolate with sufficient a priori suspicion of a role in infection, we recommend 16S rRNA sequencing or identification via the Apycoryne biochemical identification system (4,16).…”

Section: Discussionmentioning

confidence: 99%

“…Increasingly, commensal bacteria are identified as being clinically significant in specific types of infections, and laboratorians must continuously update reporting algorithms to exclude potential pathogens from the diphtheroid classification (2,13). As the population ages, with a rise in the number immunosuppressed hosts, numbers of infections caused by these opportunistic pathogens residing in our microbiome are expected to rise accordingly (2).…”

Section: Discussionmentioning

confidence: 99%

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Clinical Significance of Commensal Gram-Positive Rods Routinely Isolated from Patient Samples

2016

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Commensal bacteria from the skin and mucosal surfaces are routinely isolated from patient samples and considered contaminants. The majority of these isolates are catalase-positive Gram-positive rods from multiple genera routinely classified as diphtheroids. These organisms can be seen upon Gram staining of clinical specimens or can be isolated as the predominant or pure species in culture, raising a priori suspicion of a possible involvement in infection. With the development and adoption of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), suspicious isolates are now routinely identified to the species level. In this study, we performed a retrospective data review (2012 to 2015) and utilized site-specific laboratory criteria and chart reviews to identify species within the diphtheroid classification representative of true infection versus contamination. Our data set included 762 isolates from 13 genera constituting 41 bacterial species. Only 18% represented true infection, and 82% were deemed contaminants. Clinically significant isolates were identified in anaerobic wounds (18%), aerobic wounds (30%), blood (5.5%), urine (22%), cerebrospinal fluid (24%), ophthalmologic cultures (8%), and sterile sites (20%). Organisms deemed clinically significant included multiple Actinomyces species in wounds, Propionibacterium species in joints and cerebrospinal fluid associated with central nervous system hardware, Corynebacterium kroppenstedtii (100%) in breast, and Corynebacterium striatum in multiple sites. Novel findings include clinically significant urinary tract infections by Actinomyces neuii (21%) and Corynebacterium aurimucosum (21%). Taken together, these findings indicate that species-level identification of diphtheroids isolated with a priori suspicion of infection is essential to accurately determine whether an isolate belongs to a species associated with specific types of infection. C linical microbiology specimens frequently grow variable levels of commensal bacteria from the skin and mucosal surfaces in addition to true pathogens (1). The majority of these isolates are aerobic, asporogenic, irregularly shaped, non-partially-acid-fast, catalase-positive, Gram-positive rods from multiple genera with nondistinct colony morphology, routinely classified as diphtheroids (2). The term diphtheroid and coryneform are interchangeable, and for a comprehensive review of bacterial genera classified as coryneform bacteria, see two excellent reviews by Bernard et al. (2,3). In brief, the medically relevant genera whose morphological and biochemical descriptions fit in the diphtheroid classification include Arcanobacterium, Arthrobacter, Brevibacterium, Cellulomonas, Cellulosimicrobium, Corynebacterium (non-diphtheriae), Curtobacterium, Dermabacter, Exiguobacterium, Helcobacillus, Janibacter, Knoellia, Leifsonia, Microbacterium, Pseudoclavibacter, and Trueperella (2-4).Additionally, certain species within other genera share some but not all features of diphtheroids, are part of t...

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Section: Discussionsupporting

confidence: 89%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Clinical Significance of Commensal Gram-Positive Rods Routinely Isolated from Patient Samples

2016

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Does the human placenta delivered at term have a microbiota? Results of cultivation, quantitative real-time PCR, 16S rRNA gene sequencing, and metagenomics

Theis

Romero

Winters

et al. 2019

American Journal of Obstetrics and Gynecology

209

203

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BACKGROUND: The human placenta has been traditionally viewed as sterile, and microbial invasion of this organ has been associated with adverse pregnancy outcomes. Yet, recent studies that utilized sequencing techniques reported that the human placenta at term contains a unique microbiota. These conclusions are largely based on the results derived from the sequencing of placental samples. However, such an approach carries the risk of capturing background-contaminating DNA (from DNA extraction kits, polymerase chain reaction reagents, and laboratory environments) when low microbial biomass samples are studied. OBJECTIVE: To determine whether the human placenta delivered at term in patients without labor who undergo cesarean delivery harbors a resident microbiota ("the assemblage of microorganisms present in a defined niche or environment"). STUDY DESIGN: This cross-sectional study included placentas from 29 women who had a cesarean delivery without labor at term. The study also included technical controls to account for potential backgroundcontaminating DNA, inclusive in DNA extraction kits, polymerase chain reaction reagents, and laboratory environments. Bacterial profiles of placental tissues and background technical controls were characterized and compared with the use of bacterial culture, quantitative real-time polymerase chain reaction, 16S ribosomal RNA gene sequencing, and metagenomic surveys. RESULTS: (1) Twenty-eight of 29 placental tissues had a negative culture for microorganisms. The microorganisms retrieved by culture from the remaining sample were likely contaminants because corresponding 16S ribosomal RNA genes were not detected in the same sample.(2) Quantitative real-time polymerase chain reaction did not

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A rare case of Corynebacterium riegelii urosepsis: Role of the MALDI-TOF mass spectrometry in the identification of emerging pathogens

Pichon

Micaëlo

Longuet³

et al. 2019

Médecine et Maladies Infectieuses

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Clinical significance of coryneform Gram-positive rods from blood identified by MALDI-TOF mass spectrometry and their susceptibility profiles – a retrospective chart review

Cited by 9 publications

References 18 publications

Clinical Significance of Commensal Gram-Positive Rods Routinely Isolated from Patient Samples

Clinical Significance of Commensal Gram-Positive Rods Routinely Isolated from Patient Samples

Does the human placenta delivered at term have a microbiota? Results of cultivation, quantitative real-time PCR, 16S rRNA gene sequencing, and metagenomics

A rare case of Corynebacterium riegelii urosepsis: Role of the MALDI-TOF mass spectrometry in the identification of emerging pathogens

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