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- Ramezani, Amir, et al.
(författare)
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A Pilot Evaluation of a Rapid Screening Test for Nosocomial Infection at a Neurosurgical Intensive Care Unit in Sweden
- 2020
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Ingår i: Point of Care. - : Lippincott Williams & Wilkins. - 1533-029X .- 1533-0303. ; 19:3, s. 63-71
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Tidskriftsartikel (refereegranskat)abstract
- Background: When postneurosurgery patients develop fever, there are no convenient methods to immediately indicate the site of infection. The choice of empirical antibiotic therapy is evidently different in nosocomial meningitis compared with ventilator-associated pneumonia or urinary tract infection. Conventional bacterial cultures run a risk of being false negative due to antibiotic prophylaxis, and direct microscopic analysis of cerebrospinal fluid (CSF) from such patients has limited diagnostic value. Because of the substantial mortality associated with nosocomial meningitis, broad spectrum antibiotics in high dosage are, therefore, commonly administered. Neutrophils as a part of the innate immunity system, trap and kill bacteria by neutrophil extracellular traps (NETs). Neutrophil extracellular traps are composed of extracellular DNA which is released to the CSF during bacterial meningitis. Using a combination of sulphated-glucosaminoglycan and aniline dyes, a measurement method was developed that reacts to extracellular host DNA and changes color within 1 minute in proportion to the amount of NETs in the body fluid tested. The present study aimed to evaluate the sensitivity and specificity of the "rapid NETs test" in identifying the site of infection. Methods: We performed analysis on the left-over CSF samples (n = 199) that were collected routinely at neurosurgical intensive care unit. No samples were included after patients were transferred to the ward. Besides CSF, bronchoalveolar fluid, and urine samples were collected in febrile patients. The "rapid NETs test" was used for simultaneous analysis of the fresh left-over samples. The final diagnosis was settled at discharge. Results: A total of 75 (64%) patients had received empirical antibiotic therapy against nosocomial meningitis, whereas only 19 patients of these cases (16%) had a verified diagnosis. The rapid NETs test could distinguish a verified meningitis (n = 19) with 89.5% sensitivity and 92.5% specificity. The test also identified ventilator-associated pneumonia (n = 32) with 93.8% sensitivity and 86.8% specificity. However, the test was not reliable in identifying nosocomial urinary tract infection (sensitivity and specificity, 78.6% and 55.2%, respectively). Conclusions: The rapid NETs test indicated the site of infection in febrile patients postneurosurgery with clinically relevant sensitivity and specificity, which might show its potential to minimize the unnecessary use of antibiotics.
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| 2. |
- Ramezani, Amir, 1964-
(författare)
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A Rapid Differential Diagnostic Method for Detection of Post-Neurosurgical Infections
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This work pertains to the application of a biochemical assay with the purpose of monitoring for and early discovery of an active bacterial infection through direct sampling and rapid testing of the Cerebrospinal Fluid (CSF). A diagnostic device is described and evaluated, which aids in quickly discerning, verifying, or ruling out active infection at the injury site. We have applied it on post-neurosurgical wounds, the state of which, due to their complexity, is challenging to determine with certainty, using conventional means. Infection is the successful invasion and degeneration of the body tissue by pathogenic microorganisms. Even successfully performed invasive treatments are susceptible to infections that may not be discovered until severe complications arise. The primary sampling access to the brain for diagnostic purposes is via the CSF, which is also highly valuable for the present end. Notwithstanding this possibility, it is difficult to distinguish between cases with aseptic inflammation and meningitis, despite available methods such as cell counting, culture, and protein analysis. Therefore, current treatment options rely mainly on broad and/or prophylactic measures with few options for monitoring the results. Under normal circumstances, the body reacts immediately to infection in an immune-competent host. The initial event of the body defense is the recruitment of neutrophils to the injury site, where inflammation induces increased permeability of vessels, development of edema, and increased internal pressure inside the afflicted tissue. The brains constrained, well-protected intracranial environment has the disadvantage that swelling of the brain early causes increased pressure, which potentially exerts irreversible damaging effects on the brain tissues. Septic and aseptic inflammations and related hemorrhages that cause increased intracranial pressure are important reasons for invasive interventions to decrease the pressure. Infection is a major cause of inflammation, swelling, and increased intracranial pressure. Timely diagnosis of infection and eliminating the causative pathogens is strongly related to survival and recovery. Therefore, a prompt diagnosis of infection is essential for the immediate and appropriate initiation of antibiotic therapy and monitoring treatment effects. Further diagnostic procedures are used to identify the specific bacterial pathogens and optimize the treatment. Early discovery of infections and proper antibiotic treatment reduces complications and the need for invasive and/or repeated treatments. Non-specific immune response mediated by activated neutrophils reacts specifically and immediately to the presence of invading pathogens. The currently described diagnostic method uses the biochemical characteristics of this natural defensive mechanism. We have developed platforms for diagnostic assays to immediately discover an infection and monitor the efficacy of the appropriate antibiotic treatment against the infection. Neutrophil Extracellular Traps (NETs) are chromatin particles extruded from activated neutrophils to the site of infection to trap and kill the pathogenic microorganisms. NETs contain extracellular polyanion DNA with a high affinity to aniline dyes, as well as for proteins. This activity correlates with the expression of acute-phase proteins. The interaction of mesenchymal and epithelial cells after organ injuries enhances cytokine production, such as hepatocyte growth factor (HGF). HGF is a glycoprotein with unique properties that contribute to wound healing after injuries. The release and role of HGF during infectious diseases have been investigated and are presented here with particular emphasis on pneumonia and meningitis. In the current thesis, both clinical and preclinical assays are employed. Initially, through a preclinical experiment, we have found that upon activation by bacteria, healthy neutrophils extrude DNA particles in vitro. In a pre-mixed pink-red dextran sulfate and toluidine blue solution, the addition of DNA particles causes a visible color change to blue and a change in wavelength for absorbance of light from 542 to 620 nm. This reaction is inhibited when the bacteria in the in vitro experiment are pre-incubated with effective antibiotics. Furthermore, in clinical studies, we have compared the cerebrospinal fluid (CSF) from patients with post neurosurgical bacterial meningitis with controls that had aseptic inflammation post neurosurgery. We have assessed the clinical performance of this diagnostic platform to distinguish the cases with post neurosurgical infection such as post neurosurgical meningitis (PNM) or ventilator-associated pneumonia by analysis of CSF or tracheal secretion long before the other tests can identify the infection. Simultaneous enhanced production of HGF locally at the site of injury was demonstrated. For a comprehensive assessment, diagnosis and treatment decisions must consider the case history and development of the patient’s condition over time. Experienced neurosurgeons with independent studying habits that have conducted comparative studies on patient records, regarding which conditions and indications precede and follow the incidence of which specific diseases, have diligent routines for monitoring results of their medical decisions, and are competent at utilizing numerous diagnostic options correctly and thus at arriving at the most appropriate conclusions.
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