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The Alpha-defensin Test for Periprosthetic Joint Infection Responds to a Wide Spectrum of Organisms.

Deirmengian C, Kardos K, Kilmartin P, Gulati S, Citrano P, Booth RE - Clin. Orthop. Relat. Res. (2015)

Bottom Line: Median alpha-defensin levels were calculated for each group, and Dunn's multiple comparison test for nonparametric data was used to identify any statistically significant (p < 0.05) organism-specific differences in the alpha-defensin level.The alpha-defensin test provides consistent results regardless of the organism type, Gram type, species, or virulence of the organism and should be seriously considered to be a standard diagnostic tool in the evaluation for PJI.Level III, diagnostic study.

View Article: PubMed Central - PubMed

Affiliation: CD Diagnostics Inc, Claymont, DE, USA.

ABSTRACT

Background: The alpha-defensin test has been previously demonstrated to be highly accurate in the diagnosis of prosthetic joint infection (PJI), nearly matching the Musculoskeletal Infection Society definition for PJI. However, the relationship between alpha-defensin levels and differing infecting organism has not yet been investigated.

Questions/purposes: The purpose of this study is to describe the breadth of organisms that can trigger a positive synovial fluid alpha-defensin test result in the setting of PJI and also to assess the magnitude of the alpha-defensin result in terms of various pathogen characteristics.

Methods: Between December 2012 and March 2014, one laboratory processed 2319 synovial fluid samples for alpha-defensin testing. The present study reviewed the results of the 1937 samples that simultaneously had a synovial fluid culture performed; these came from 418 surgeons in 42 states. The overall culture-positive rate was 49% (244 of 498) among alpha-defensin-positive synovial fluids and 1% (19 of 1439) among alpha-defensin-negative synovial fluids. The organisms recovered from 244 alpha-defensin-positive, culture-positive fluids were recorded and grouped based on various characteristics, including Gram type, species, virulence, oral pathogenicity, and source joint. Alpha-defensin-negative samples served as uninfected controls. Median alpha-defensin levels were calculated for each group, and Dunn's multiple comparison test for nonparametric data was used to identify any statistically significant (p < 0.05) organism-specific differences in the alpha-defensin level.

Results: The alpha-defensin test for PJI was positive in the setting of a wide spectrum of organisms typically causing PJI. The median alpha-defensin level for all 244 alpha-defensin-positive, culture-positive samples (4.7 [interquartile range {IQR}, 3.7-5.3]) was higher than negative controls (0.26 [IQR, 0.22-0.33]) with a median difference of 4.4 (p < 0.001). There were no differences in the median alpha-defensin levels when performing a multiple comparison test among Gram-positive organisms (4.7 [IQR, 3.6-5.3]), Gram-negative organisms (4.8 [IQR, 4.2-5.3]), yeast (4.1 [IQR, 2.2-5.1]), virulent organisms (4.7 [IQR, 3.8-5.2]), less virulent organisms (4.8 [IQR, 3.6-5.4]), oral pathogens (4.5 [IQR, 3.2-5.2]), knees (4.7 [IQR, 3.7-5.3]), hips (4.9 [IQR, 4.1-5.8]), or shoulders (5.3 [IQR, 4.0-10.7]) with all comparisons having a p > 0.999.

Conclusions: The alpha-defensin test provides consistent results regardless of the organism type, Gram type, species, or virulence of the organism and should be seriously considered to be a standard diagnostic tool in the evaluation for PJI. Future research should focus on the performance of this test in specific clinical scenarios such as the immediate postoperative period in the setting of severe immunocompromise and in the setting of a native joint.

Level of evidence: Level III, diagnostic study.

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Related in: MedlinePlus

Synovial fluid samples with both a positive alpha-defensin result and a positive culture were grouped by organism species. Median values and the IQRs are plotted on a log scale. *** = Different with statistical significance.
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Fig3: Synovial fluid samples with both a positive alpha-defensin result and a positive culture were grouped by organism species. Median values and the IQRs are plotted on a log scale. *** = Different with statistical significance.

Mentions: Similarly, when comparing S/CO levels for causative organisms against control levels, all groups were greater than the negative control (S epidermidis median 4.9 [IQR, 4.1–5.6], S aureus median 4.5 [IQR, 3.2–5.3], S caprae median 4.6 [IQR, 3.7–5.3], S lugdunensis median 4.2 [IQR, 3.9–5.2], E faecalis median 5.2 [IQR, 4.4–5.5], S agalaciae median 4.8 [IQR, 4.6–5.1], C striatum median 4.6 [IQR, 2.9–5.2], S mitis/oralis median 4.6 [IQR, 4.5–5.2]; S epidermidis versus control median difference: 4.6, p < 0.001; S aureus versus control median difference: 4.3, p < 0.001; S caprae versus control median difference: 4.3, p < 0.001; S lugdunensis versus control median difference: 4.0, p < 0.001; E faecalis versus control median difference: 4.9, p < 0.001; S agalaciae versus control median difference: 4.5, p < 0.001; C striatum versus control median difference: 4.3, p < 0.001; S mitis/oralis versus control median difference: 4.3, p < 0.001; Fig. 3), whereas no differences were found between any species medians (all p > 0.999).Fig. 3


The Alpha-defensin Test for Periprosthetic Joint Infection Responds to a Wide Spectrum of Organisms.

Deirmengian C, Kardos K, Kilmartin P, Gulati S, Citrano P, Booth RE - Clin. Orthop. Relat. Res. (2015)

Synovial fluid samples with both a positive alpha-defensin result and a positive culture were grouped by organism species. Median values and the IQRs are plotted on a log scale. *** = Different with statistical significance.
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4457768&req=5

Fig3: Synovial fluid samples with both a positive alpha-defensin result and a positive culture were grouped by organism species. Median values and the IQRs are plotted on a log scale. *** = Different with statistical significance.
Mentions: Similarly, when comparing S/CO levels for causative organisms against control levels, all groups were greater than the negative control (S epidermidis median 4.9 [IQR, 4.1–5.6], S aureus median 4.5 [IQR, 3.2–5.3], S caprae median 4.6 [IQR, 3.7–5.3], S lugdunensis median 4.2 [IQR, 3.9–5.2], E faecalis median 5.2 [IQR, 4.4–5.5], S agalaciae median 4.8 [IQR, 4.6–5.1], C striatum median 4.6 [IQR, 2.9–5.2], S mitis/oralis median 4.6 [IQR, 4.5–5.2]; S epidermidis versus control median difference: 4.6, p < 0.001; S aureus versus control median difference: 4.3, p < 0.001; S caprae versus control median difference: 4.3, p < 0.001; S lugdunensis versus control median difference: 4.0, p < 0.001; E faecalis versus control median difference: 4.9, p < 0.001; S agalaciae versus control median difference: 4.5, p < 0.001; C striatum versus control median difference: 4.3, p < 0.001; S mitis/oralis versus control median difference: 4.3, p < 0.001; Fig. 3), whereas no differences were found between any species medians (all p > 0.999).Fig. 3

Bottom Line: Median alpha-defensin levels were calculated for each group, and Dunn's multiple comparison test for nonparametric data was used to identify any statistically significant (p < 0.05) organism-specific differences in the alpha-defensin level.The alpha-defensin test provides consistent results regardless of the organism type, Gram type, species, or virulence of the organism and should be seriously considered to be a standard diagnostic tool in the evaluation for PJI.Level III, diagnostic study.

View Article: PubMed Central - PubMed

Affiliation: CD Diagnostics Inc, Claymont, DE, USA.

ABSTRACT

Background: The alpha-defensin test has been previously demonstrated to be highly accurate in the diagnosis of prosthetic joint infection (PJI), nearly matching the Musculoskeletal Infection Society definition for PJI. However, the relationship between alpha-defensin levels and differing infecting organism has not yet been investigated.

Questions/purposes: The purpose of this study is to describe the breadth of organisms that can trigger a positive synovial fluid alpha-defensin test result in the setting of PJI and also to assess the magnitude of the alpha-defensin result in terms of various pathogen characteristics.

Methods: Between December 2012 and March 2014, one laboratory processed 2319 synovial fluid samples for alpha-defensin testing. The present study reviewed the results of the 1937 samples that simultaneously had a synovial fluid culture performed; these came from 418 surgeons in 42 states. The overall culture-positive rate was 49% (244 of 498) among alpha-defensin-positive synovial fluids and 1% (19 of 1439) among alpha-defensin-negative synovial fluids. The organisms recovered from 244 alpha-defensin-positive, culture-positive fluids were recorded and grouped based on various characteristics, including Gram type, species, virulence, oral pathogenicity, and source joint. Alpha-defensin-negative samples served as uninfected controls. Median alpha-defensin levels were calculated for each group, and Dunn's multiple comparison test for nonparametric data was used to identify any statistically significant (p < 0.05) organism-specific differences in the alpha-defensin level.

Results: The alpha-defensin test for PJI was positive in the setting of a wide spectrum of organisms typically causing PJI. The median alpha-defensin level for all 244 alpha-defensin-positive, culture-positive samples (4.7 [interquartile range {IQR}, 3.7-5.3]) was higher than negative controls (0.26 [IQR, 0.22-0.33]) with a median difference of 4.4 (p < 0.001). There were no differences in the median alpha-defensin levels when performing a multiple comparison test among Gram-positive organisms (4.7 [IQR, 3.6-5.3]), Gram-negative organisms (4.8 [IQR, 4.2-5.3]), yeast (4.1 [IQR, 2.2-5.1]), virulent organisms (4.7 [IQR, 3.8-5.2]), less virulent organisms (4.8 [IQR, 3.6-5.4]), oral pathogens (4.5 [IQR, 3.2-5.2]), knees (4.7 [IQR, 3.7-5.3]), hips (4.9 [IQR, 4.1-5.8]), or shoulders (5.3 [IQR, 4.0-10.7]) with all comparisons having a p > 0.999.

Conclusions: The alpha-defensin test provides consistent results regardless of the organism type, Gram type, species, or virulence of the organism and should be seriously considered to be a standard diagnostic tool in the evaluation for PJI. Future research should focus on the performance of this test in specific clinical scenarios such as the immediate postoperative period in the setting of severe immunocompromise and in the setting of a native joint.

Level of evidence: Level III, diagnostic study.

Show MeSH
Related in: MedlinePlus