RU2642659C1 - Diagnostic technique for near-graft infection of joints - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention relates to medicine, namely to traumatology and orthopedics and can be used to diagnose periprosthetic joint infection in endoprosthetics. Essence of method: conduct a microscopic examination of smear of aspirate, stained by Gram, and further measuring the concentration of D-lactate using the D-lactam test system, test sample is prepared by adding to the 25 mcl aspirate from the endoprosthetic joint 45 mcl of the enzyme mix and 80 mcl of the substrate mixta, turbidity control is obtained by adding 45 mcl of distilled water and 80 mcl of a substrate mix to 25 mcl of aspirate from the endoprosthetic joint; resulting mixtures are incubated in a thermostat at a temperature of 37 °C±1 °C for 30 minutes and measure the optical density of the mixtures on a plate reader using a 570–600 nm filter. Then optical density of each test sample is subtracted from difference in optical density of turbidity control and empty cell and for each test sample, the concentration is calculated from the calibration schedule and at a D-lactate value of 1.2 mmol/L and more diagnosed as periprosthetic joint infection.

EFFECT: highly accurate method for the diagnosis of periprosthetic joint infection has been proposed, which allows fast, within one hour, to identify the presence of infection in the endoprosthetic joint, caused even by hard-to-cultivate microorganisms, which will allow to widely use the claimed method in the departments of traumatology, orthopedics and endoprosthetics.

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Description

The invention relates to medicine, in particular to traumatology and orthopedics, and can be used to diagnose periprosthetic joint infection during joint replacement.

Recently, the number of joint arthroplasty operations has significantly increased worldwide. The annual increase in such manipulations varies from 5.3% to 17%. The intensive development of endoprosthetics entails an increase in the number of revisions due to the development of various complications. One of the most common is periprosthetic joint infection (FDI). The management tactics of patients with periprosthetic joint infection is completely different from that in patients with aseptic instability of implants; accordingly, a timely and accurate diagnosis of infection is crucial. A delay in diagnosis or diagnostic errors can lead to an increase in the volume of infected tissues, as a result there is a need for complex surgical operations, sometimes with relapses of the infectious process, leading to the development of serious complications, such as sepsis, up to fatal outcomes.

A known method for the diagnosis of periprosthetic joint infection by microscopic examination of a smear of an aspirate from a prosthetic joint stained by Gram, obtained by puncture of an endoprosthetic joint, with the aim of visual detection of microorganisms.

The disadvantage of this method is its inaccuracy due to the low detection of the pathogen - 45%, since the concentration of microorganisms in the joint replacement is low. Faraj AA1, Omonbude OD, Godwin P. Gram staining in the diagnosis of acute septic arthritis. Acta Orthop Belg. 2002 Oct; 68 (4): 388-91.

The closest to the technical result achieved (prototype) is a method for diagnosing periprosthetic joint infection by bacteriological examination of an aspirate from an endoprosthetic joint obtained by puncture of an endoprosthetic joint. The known method consists in sowing an aspirate from an endoprosthetic joint on a nutrient medium in order to detect the growth of microorganisms.

The disadvantages of this method are: inaccurate diagnosis due to the low detectability of microorganisms, especially in cases of difficult to cultivate microorganisms; a long incubation period of crops (up to 14 days or more), which significantly lengthens the timing of diagnosis; the complexity of the study. Kordo Saeed Diagnostics in prosthetic joint infections J. Antimicrob. Chemother. (2014) 69 (suppl 1): i11-i19.doi: 10.1093 / jac / dku248

The technical result of the proposed method is to increase the accuracy of diagnosis of periprosthetic joint infection by measuring the concentration of D-lactate (bacterial metabolite) in an aspirate from an endoprosthetic joint in case of an infectious process.

The technical result is achieved by conducting a microscopic examination of a smear of an aspirate from a prosthetic joint stained by Gram and additionally measuring the concentration of D-lactate, obtaining a test sample by adding 45 μl of enzyme mix and 80 μl of substrate mix to 25 μl of aspirate from the endoprosthetic joint, control Turbidity is obtained by adding 45 μl of distilled water and 80 μl of the substrate mix to 25 μl of an aspirate from the endoprosthetic joint; the resulting mixtures are incubated in a thermostat at a temperature of 37 ° C ± 1 ° C for 30 minutes and the optical density of the mixtures is measured on a tablet reader using a 570-600 nm light filter, then the difference in the optical density of the turbidity control and the empty cell is subtracted from the optical density of each test sample and for each test sample, the concentration is calculated according to the calibration graph and, with a D-lactate value of 1.2 mmol / l or more, a periprosthetic joint infection is diagnosed.

The authors propose a highly accurate method for diagnosing periprosthetic joint infection, which allows quickly, within one hour, to identify the presence of infection in the endoprosthetic joint caused even by difficult to cultivate microorganisms.

The implementation of the method.

The results of the study are illustrated by a figure in the form of a table.

The table gives comparative data of the claimed method with the known.

A patient with a suspected periprosthetic infection of the joints under aseptic conditions with a standard syringe performs a puncture of the endoprosthetic joint with taking an aspirate in the amount necessary for the study. The aspirate in a syringe is delivered to a laboratory for research, where a microscopic examination of a smear of an aspirate smear from an endoprosthetized joint stained by Gram is carried out and bacteriological studies and additionally measure the concentration of D-lactate in an aspirate from an endoprosthetized joint using the D-lactam test system ( Vitebsk, Republic of Belarus). The use of the “D-lactam” test system is known in ascites, pleural, cerebrospinal and synovial fluids, however, there was no study with an aspirate from the endoprosthetics joint for the presence of D-lactate.

The study is carried out in accordance with the instructions for use, which is part of the kit. A test sample is prepared by adding 45 μl of the enzyme mix and 80 μl of the substrate mix to 25 μl of the endoprosthetics joint aspirate. Turbidity control is obtained by adding 45 μl of distilled water and 80 μl of substrate to 25 μl of the aspirate from the endoprosthetic joint. The resulting mixtures were incubated in a thermostat at a temperature of 37 ° C ± 1 ° C for 30 minutes and the optical density of the mixtures was measured on a flatbed reader using a 570-600 nm light filter. Then, the difference in the optical density of the turbidity control and the empty cell is subtracted from the optical density of each test sample. For each test sample, the concentration is calculated according to a calibration graph and, with a D-lactate value of 1.2 mmol / L or more, a periprosthetic joint infection is diagnosed.

Clinical example

04/27/15, patient B. was admitted to the trauma unit with signs of periprosthetic joint infection, history No. 814. The patient under aseptic conditions performed a puncture of the endoprosthetic joint with a standard syringe with the aspirate taken from the endoprosthetic joint in the amount necessary for the study. The syringe was delivered to the laboratory for research, where a microscopic examination of a smear of an aspirate smear from an endoprosthetic joint stained by Gram, and bacteriological examination and, additionally, according to the claimed method, measurement of the concentration of D-lactate were performed. Microscopic examination of a smear of an aspirate from an endoprosthetized joint stained by Gram and bacteriological examination did not detect the pathogen, while the value of D-lactate was 1.76 mmol / L, which was regarded as a positive result and the patient was diagnosed with Periprosthetic joint infection ". In this regard, the patient was referred for revision endoprosthetics in order to remove infected implants. A bacteriological examination of the implants extracted during the operation after 14 days confirmed the presence of a periprosthetic infection caused by a difficult-to-cultivate microorganism - Propionibacterium acnes. Thus, having identified the infectious process in the early stages, using the claimed method, the infection site (implant) was removed 14 days earlier, which significantly improved the treatment result, prevented systemic inflammation and prevented repeated extensive highly traumatic surgical interventions.

In the laboratory, an assessment was made of the effectiveness of measuring the concentration of D-lactate in an aspirate from an endoprosthetic joint in comparison with a bacteriological study and a microscopic examination of a smear of an aspirate from an endoprosthetic joint stained with Gram stain. The sensitivity of the claimed method was 97%, specificity - 94%, which indicates high accuracy.

As can be seen from the table, the number of confirmed cases of periprosthetic joint infection by the present method when measuring the concentration of D-lactate in an aspirate from an endoprosthetic joint is 97%, that is, higher than with a bacteriological study (prototype) - 75% and a microscopic examination of an aspirate smear from an endoprosthetic joint, Gram stained - 53%. In addition, in 8 patients the infectious process was detected only using the claimed method, which consists in additionally measuring the concentration of D-lactate in the aspirate from the endoprosthetics joint in comparison with bacteriological examination and in 16 patients in comparison with microscopic examination. This made it possible to change the management tactics of such patients in the early stages, use antibiotic therapy and achieve a cure. It also made it possible to avoid repeated highly traumatic extensive surgical revision interventions leading to disability of the patient. The lack of detection of infection in such patients threatens to develop serious complications, such as sepsis, up to fatal outcomes.

The inventive method allows for accurate diagnosis of periprosthetic joint infection, as quickly, within one hour, it identifies cases of periprosthetic joint infection, even caused by difficult to cultivate microorganisms, and ensures the availability of diagnostics of periprosthetic joint infection, which makes it possible to widely use the inventive method in departments of traumatology, orthopedics and endoprosthetics .

Claims (1)

A method for diagnosing periprosthetic joint infection by bacteriological examination of an aspirate obtained by puncture from an endoprosthetic joint, characterized in that a microscopic examination of a smear of an aspirate stained with Gram stain is carried out, and an additional measurement of the concentration of D-lactate using the D-lactam test system is obtained, test sample by adding 45 μl of enzyme mix and 80 μl of substrate mix to 25 μl of endoprosthetics aspirate joint; turbidity control is obtained by adding to 25 μl of the aspirate from the endoprosthesis replacement joint 45 μl of distilled water and 80 μl of the substrate mixed; the resulting mixtures are incubated in a thermostat at a temperature of 37 ° C ± 1 ° C for 30 minutes and the optical density of the mixtures is measured on a tablet reader using a 570-600 nm light filter, then the difference in the optical density of the turbidity control and the empty cell is subtracted from the optical density of each test sample and for each test sample, the concentration is calculated according to the calibration graph and, with a D-lactate value of 1.2 mmol / l or more, a periprosthetic joint infection is diagnosed.