Can serum procalcitonin help to differentiate between septic and nonseptic arthritis?

Determining the accuracy of the leukocyte esterase reagent strip test in the rapid diagnosis of adult septic arthritis

BACKGROUNDS

Septic arthritis is a dangerous disease that occurs when microorganisms enter synovial fluid. It needs fast and accurate management; otherwise, it can harm the patient's life. Currently, the tests measure WBC and PMN in SF, so we hypothesized to use a proxy that is easier and faster to measure. Leukocyte esterase is an enzyme secreted by neutrophils that can be found in the synovial fluid of SA patients. In this study, we tried to investigate the sensitivity and specificity of leukocyte esterase in diagnosing septic arthritis.

METHODS

We obtained synovial fluid samples from forty-six patients suspected of having septic arthritis and fifty-eight healthy individuals and measured the WBCs, ESR, CRP, PMN, glucose, and protein of SF in 2021. We also used the leukocyte esterase dipstick test to investigate the level of LE in synovial fluid for one minute.

RESULTS

Based on clinical and paraclinical criteria, sixteen out of the forty-six patients were diagnosed with SA. When (++) was considered positive, the sensitivity and specificity of the LE dipstick test for the diagnosis of SA were 93.7% (95% CI: 81.8-100%) and 60% (95% CI: 42.4-77.5%, P = 0.000), respectively. When both (+) and (++) were considered positive, they were 100% and 43.3% (95% CI: 25.6-61.0% P = 0.000), respectively. All the patients in the control group had negative cultures and LE test readings (specificity = 100%).

CONCLUSION

The LE dipstick test can be a valuable diagnostic tool in the initial diagnosis of SA since it is affordable, fast, and reliable.

Comparison of Procalcitonin With Commonly Used Biomarkers and Algorithms for Evaluating Suspected Pediatric Musculoskeletal Infection in the Emergency Department

INTRODUCTION

It is difficult to distinguish between children with infectious versus noninfectious conditions of the musculoskeletal system during initial evaluation. Clinical predictive algorithms potentially support this effort but not without limitations. Procalcitonin (PCT) has been proposed as a biomarker to help differentiate infection from noninfection. This study evaluates the adoption and utility of PCT during initial infection evaluations and assesses test characteristics of commonly used parameters and algorithms.

METHODS

PCT was introduced for initial laboratory evaluation of the suspected musculoskeletal infection. Prospective enrollment occurred from July 2020 to November 2021 with 3 cohorts established after a retrospective review of final diagnoses at the end of treatment: 1) deep infection, 2) superficial infection, and 3) noninfection. Univariate and multivariate logistic regression analysis of parameters and diagnoses was performed. Test characteristics of individual and aggregated parameters were assessed.

RESULTS

Among 258 children evaluated, 188 (72.9%) had PCT drawn during the evaluation. An increase of PCT acquisition from 67.8% to 82.4% occurred over the study timeframe. Eighty-five children were prospectively studied, including those with deep infection (n=21); superficial infection (n=10), and noninfection (n=54). Test characteristics of parameters showed accuracy ranging from 48.2% to 85.9%. PCT >0.1 ng/mL independently predicted deep infection in 84.7% of cases, outperforming white blood cell, C-reactive protein (CRP), and absolute neutrophil count. Using study thresholds for CRP, erythrocyte sedimentation rate, PCT, and Temp improved accuracy to 89.4%.

CONCLUSIONS

PCT is a potentially useful biomarker during the initial assessment of children suspected to have a musculoskeletal infection. Systematic evaluation using a combination of parameters improves the accuracy of assessment and assists predictive judgment under uncertainty. PCT <0.1 ng/mL, erythrocyte sedimentation rate <18 mm/hr, CRP <3.3 mg/dL, and temperature <37.8°C should reasonably reassure clinicians that deep musculoskeletal infection is less likely, given the high negative predictive value and collective accuracy of these parameters.

LEVEL OF EVIDENCE

Level III - Retrospective cohort comparison.

Procalcitonin as a Predictor of Septic Knee Arthritis: A Retrospective Cohort Study

INTRODUCTION

Differentiating septic arthritis from aseptic arthritis (AA) of the knee is difficult without arthrocentesis. Although procalcitonin (PCT) has shown diagnostic value in identifying bacterial infections, it has not been established as a reliable marker for identifying septic arthritis (SA). Recent studies have shown promise in the use of PCT as a useful systemic marker for identifying septic arthritis versus AA. This observational retrospective review compares PCT with routine inflammatory markers as a tool for differentiating septic arthritis versus AA in patients with acute, atraumatic knee pain.

METHODS

Fifty-three consecutive patients (24 SA, 29 AA) were retrospectively reviewed at one institution with concern for SA. SA was diagnosed based on a physical examination, laboratory markers, and arthrocentesis. Laboratory indices were compared between the septic arthritis and AA groups. Data analysis was conducted to define sensitivity and specificity. Receiver operator characteristic curve analysis and regression were conducted to determine the best marker for acute SA of the knee.

RESULTS

Using multiple logistic regression, bacteremia (OR 6.75 ± 5.75) was determined to be the greatest predictor of SA. On linear regression, concomitant bacteremia (coef 3.07 ± 0.87), SA (coef 2.18 ± 0.70), and the presence of pseudogout crystals (coef 1.80 ± 0.83) on microscopy predicted an increase in PCT. Using a PCT cutoff of 0.25 ng/mL yields a sensitivity of 91.7% and specificity of 55.2% for predicting SA; however, the ideal cutoff in our series was 0.32 ng/mL with a sensitivity of 79.2% and specificity of 72.4%. PCT was superior to the white blood cell count, erythrocyte sedimentation rate, and C-reactive protein in the area under the receiver-operating characteristic curve analysis.

DISCUSSION

Procalcitonin seems to be the most sensitive and specific systemic marker in differentiating septic from AA.

What are the best diagnostic tests for diagnosing bacterial arthritis of a native joint? : a systematic review of 27 studies

AIMS

This study aimed to answer two questions: what are the best diagnostic methods for diagnosing bacterial arthritis of a native joint?; and what are the most commonly used definitions for bacterial arthritis of a native joint?

METHODS

We performed a search of PubMed, Embase, and Cochrane libraries for relevant studies published between January 1980 and April 2020. Of 3,209 identified studies, we included 27 after full screening. Sensitivity, specificity, area under the curve, and Youden index of diagnostic tests were extracted from included studies. We grouped test characteristics per diagnostic modality. We extracted the definitions used to establish a definitive diagnosis of bacterial arthritis of a native joint per study.

RESULTS

Overall, 28 unique diagnostic tests for diagnosing bacterial arthritis of a native joint were identified. The following five tests were deemed most useful: serum ESR (sensitivity: 34% to 100%, specificity: 23% to 93%), serum CRP (sensitivity: 58% to 100%, specificity: 0% to 96%), serum procalcitonin (sensitivity: 0% to 100%, specificity: 68% to 100%), the proportion of synovial polymorphonuclear cells (sensitivity: 42% to 100%, specificity: 54% to 94%), and the gram stain of synovial fluid (sensitivity: 27% to 81%, specificity: 99% to 100%).

CONCLUSION

Diagnostic methods with relatively high sensitivities, such as serum CRP, ESR, and synovial polymorphonuclear cells, are useful for screening. Diagnostic methods with a relatively high specificity, such as serum procalcitonin and synovial fluid gram stain, are useful for establishing a diagnosis of bacterial arthritis. This review helps to interpret the value of various diagnostic tests for diagnosing bacterial arthritis of a native joint in clinical practice. Cite this article: Bone Joint J 2021;103-B(12):1745-1753.

Current Guideline for Diagnosis of Periprosthetic Joint Infection: A Review Article

The nature of implant-related infections is complex. Currently, there is no definitive test for periprosthetic joint infection (PJI) and diagnosis remains challenging despite recent developments. Failure to diagnose and investigate pathologies of the hip appropriately results in delayed management and prolonged patient morbidity. A systematic approach to establishing clear diagnostic criteria for PJI is needed to improve our ability to avoid devastating outcomes associated with these infections. In the current review, we describe an algorithmic approach to the diagnosis of PJI and current controversies surrounding novel diagnostic methods.

Increased perioperative C-reactive protein and decreased postoperative albumin is associated with acute posttraumatic osteomyelitis in patients with high-energy tibial fractures

BACKGROUND

Early diagnosis of acute posttraumatic osteomyelitis (POM) is of vital importance for avoiding devastating complications. Diagnosing POM is difficult due to the lack of a highly specific and sensitive test, such as in myocardial infarct, stroke and intracranial bleeding. Serum inflammatory markers, C-reactive protein (CRP), procalcitonin (PCT), white blood cells (WBC) can support clinical findings but they are not able to differentiate between inflammatory response to infection and the host response to non-infection insult with high specificity and sensitivity.

AIM

The objectives of the study were to investigate whether the biochemical and immunoinflammatory patient profile could facilitate postoperative monitoring, guide the antibiotic treatment and timing of revision surgery.

PATIENTS AND METHODS

This prospective nonrandomised cohort study included 86 patients after high-energy injury to the shin requiring primary surgical treatment (open or closed reduction and internal fixation of tibial fracture). Values of the biochemical and immunoinflammatory profile were measured on admission (ADD), first postoperative day (POD1) and fourth-postoperative day (POD4).

RESULTS

We discovered on our sample that the development of POM is associated with increased CRP on ADD, POD1 and decreased albumins on POD4. Further studies are needed to prove that these differences can be useful in diagnosing the risk of infection. The assessment of other important risk factors such as: the extent of soft tissue damage, multiple fractures, transfusion rate, need for conversion primary external fixation to intramedullary (IM) nailing or locking plate fixation can empower our clinical judgment of POM.

CONCLUSIONS

We can improve prediction of posttraumatic osteomyelitis by using the perioperative inflammatory biomarker CRP in combination with postoperative albumins levels and other associated independent risk factors.

Value of procalcitonin for diagnosing perioperative pneumonia, urinary infections and superficial surgical site infections in patients undergoing primary hip and knee arthroplasty

Serum procalcitonin (PCT) levels may be helpful for the diagnosis of infections during the perioperative period of arthroplasty. However, there is much debate in the literature regarding the appropriate cut-off value for different types of surgery and local bacterial infection. The present study aimed to evaluate serum PCT levels in patients undergoing arthroplasty and to determine the cut-off value that may represent perioperative pneumonia, urinary infections and superficial surgical site infections. The present retrospective study included a total of 500 patients treated between July 2014 and August 2015. The case group contained 25 patients with perioperative infections (pneumonia, urinary and superficial surgical site infections), and the control group contained 25 patients without any post-surgical complications. Serum levels of PCT and white blood cells (WBC) were measured pre-operatively (D0) and at post-operative D4, D6 and D8, and the sensitivity, specificity and predictive value of these parameters were assessed. Regarding the comparison of the mean PCT levels between the case and the control group, a significant difference was seen at D8 (P=0.007), while no significant differences were observed at D0 (P=0.010), D4 (P=0.069) and D6 (P=0.093). No statistically significant differences in WBC levels between groups were observed for (P>0.01). In the control group, the PCT levels at D4 (0.062±0.020 ng/ml) were 2-fold of the mean baseline value, followed by a decrease until D6 (0.051±0.019 ng/ml) and a return close to the normal range by D8 (0.032±0.015 ng/ml). The PCT levels in the case group had rapidly increased on D4 (0.510±1.208 ng/ml). In contrast to the control group, they continuously increased on D6 (0.527±1.360 ng/ml) and D8 (0.686±1.117 ng/ml). From a clinical point of view, infection events were indicated in these patients during post-operative follow-up. For PCT, the area under the receiver operating characteristic curve (AUC) was 0.978 [95% confidence interval (CI), 0.933-1.022], and for WBC, the AUC was 0.562 (95% CI, 0.398-0.0.726). Based on the above data, the PCT value was a significant predictor of infection (AUC>0.9). For PCT, the cut-off point of 0.0995 ng/ml was associated with a sensitivity of 96% and a specificity of 100%. However, WBC were not a significant predictor of infection (0.5<AUC<0.7), and the cut-off value of 7.05×10⁹/l was associated with a sensitivity of 64% and a specificity of 44%. In conclusion PCT was found to be a promising marker for diagnosing bacterial infections post-arthroplasty due to its high specificity. Based on the sensitivity and the specificity, detecting PCT may be more valuable than using WBC in the diagnosis of sepsis-associated pathological changes in the perioperative period.

Serum procalcitonin levels as a diagnostic marker for septic arthritis: A meta-analysis

BACKGROUND

The aim of this study was to assess the value of serum procalcitonin (PCT) levels as a diagnostic marker for septic arthritis (SA) via meta-analysis.

METHODS

We searched PubMed, Embase and the Cochrane Library, as well as the reference lists of relevant articles, for studies published up to May 21, 2015 and did not impose language restrictions. We selected original studies reporting the usefulness of PCT or C-reactive protein (CRP) as a diagnostic marker for SA. We summarized test performance characteristics with the use of forest plots, hierarchical summary receiver operating characteristic curves, and bivariate random effects models. Prespecified subgroup analyses and meta-regression analyses were also performed.

RESULTS

This meta-analysis comprised 10 studies including 838 patients. The overall sensitivity of serum PCT levels for the diagnosis of SA in these studies was 0.54 (95% CI, 0.41-0.66), and the specificity of PCT was 0.95 (95% CI, 0.87-0.98). The positive likelihood ratio (LR) was 10.97 (95% CI, 4.65-25.89); the negative LR was 0.49 (95% CI, 0.38-0.62); and the area under ROC curve (AUROC) was 0.82 (95% CI, 0.78-0.85). Six studies also examined the usefulness of CRP levels as a marker for the diagnosis of SA. The sensitivity and specificity of CRP were 0.45 (95% CI, 0.35-0.55) and 0.079 (95% CI, 0.0.021-0.25), respectively, and the positive LR, negative LR and AUROC curve were 0.48 (95% CI, 0.39-0.61), 6.79 (95% CI, 2.04-23.81), and 0.30 (95% CI, 0.26-0.34), respectively.

CONCLUSION

PCT is more valuable than CRP for distinguishing SA from non-SA.

Advancements in Diagnosing Periprosthetic Joint Infections after Total Hip and Knee Arthroplasty

Periprosthetic joint infection (PJI) is a complication of total joint arthroplasty that is challenging to diagnose. Currently, there is no "gold standard" for definite diagnosis of PJI. A multi-criteria definition has been described for PJI based on microbiology cultures, serum markers, such as erythrocyte sedimentation rate and C-reactive protein (CRP), synovial fluid biomarkers, such as leukocyte esterase and histopathology assessment of the periprosthetic tissue. The conventional serum markers are generally nonspecific and can be elevated in inflammatory conditions. Therefore, they cannot be relied on for definite diagnosis of PJI. Hence, with the use of proteomics, synovial fluid biomarkers such as α-defensin, IL-6, and CRP have been proposed as more accurate biomarkers for PJI. Current methods to culture micro-organisms have several limitations, and can be false-negative and false-positive in a considerable number of cases. In an attempt to improve culture sensitivity, diagnostic methods to target biofilms have recently been studied. The understanding of the concept of biofilms has also allowed for the development of novel techniques for PJI diagnosis, such as visualizing biofilms with fluorescent in-situ hybridization and detection of bacteria via DNA microarray. Lastly, the use of amplification-based molecular techniques has provided methods to identify specific species of bacteria that cause culture-negative PJI. While diagnosing PJI is difficult, these advances could be valuable tools for clinicians.

Diagnosis of Periprosthetic Infection: Novel Developments

The diagnosis of periprosthetic joint infection (PJI) has been performed by obtaining a history and physical examination, blood tests, and analysis of the synovial fluid and tissue samples. The measurement of serum biomarkers are routinely used to diagnose PJI. These markers may be elevated in other inflammatory conditions, necessitating the need for more specific biomarkers to diagnose PJI. Serum biomarkers may be more specific to PJI. Synovial CRP, α-defensin, human β-defensin-2 and -3, leukocyte esterase, and cathelicidin LL-37 biomarkers hold promise for the diagnosis of PJI.

Synovial IL-6 as inflammatory marker in periprosthetic joint infections

We analyzed serum and synovial biomarkers of 69 patients. 31 of them suffered from a periprosthetic joint infection (PJI) and 38 from aseptic arthralgia after total joint arthroplasty. We used Receiver-Operating-Characteristic-curves to calculate the Area-under-the-curve (AUC), cutoff-values, positive (+LR), negative (-LR) and interval-Likelihood-Ratios (iLR) for predicting a PJI. The most significant parameter was synovial interleukin-6 (IL-6) (cutoff-value ≥ 30,750 pg/ml, AUC = 0.959, SE = 90.0%, SP = 94.7%, +LR = 17.27), followed by synovial lactate (cutoff-value ≥ 8.3 mmol/l, AUC = 0.844, SE = 71.4%, SP=88.0%, +LR = 5.95), and synovial glucose (cutoff-value ≤ 44 mg/dl, AUC = 0.829, SE = 79.2%, SP = 78.6%, +LR = 3.69). IL-6 ≥ 30,750 pg/ml and lactate ≥ 10 mmol/l make a PJI very likely, IL-6 <10,000pg/ml or lactate <4.3 mmol/l makes a PJI very unlikely. If none of these thresholds are met, physicians should use the iLR of IL-6, glucose and lactate to estimate the likelihood of PJI.

Serum procalcitonin levels in patients with ankylosing spondylitis

AIM

Procalcitonin is a marker of bacterial and fungal infection and sepsis. The present study evaluated the relationship between serum procalcitonin levels and disease activity in patients with ankylosing spondylitis (AS).

METHOD

A total of 61 patients who met the 1984 New York criteria for AS were studied. Twenty-four age- and sex-matched healthy volunteers were recruited to this study as a control group. Disease activity was assessed by the Bath AS Disease Activity Index (BASDAI). The functional status of patients was evaluated by the Bath AS Functional Index (BASFI). Spinal mobility was measured by the Bath AS Metrology Index (BASMI). Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and serum procalcitonin levels were measured.

RESULTS

Thirty patients were on anti-tumor necrosis factor-alpha treatment and 31 patients were on conventional treatment. Seventeen (28%) of the AS patients were active (BASDAI > 4) and 44 (72%) of the AS patients were in remission. The median ESR was 14 (34-6) mm/h and 4 (7-2) mm/h (P < 0.001) for the patient and control groups, respectively. The median CRP level was 0.91 (2.72-0.37) mg/dL and 0.15 (0.25-0.07) mg/dL in the patient and control groups, respectively (P < 0.001). Median BASDAI, BASFI and BASMI scores for all AS patients were 3.6 (5.25-2.29), 2.5 (4.22-0.91) and 3 (5-1), respectively. Serum procalcitonin levels were normal (< 0.05 ng/mL) for all patients and controls.

CONCLUSION

Serum procalcitonin levels were not high in AS patients and controls, and the levels were independent of disease activity and medications. If bacterial or fungal infection is suspected in an AS patient, serum procalcitonin level may be useful for diagnosis.

Serum C-reactive protein and procalcitonin kinetics in patients undergoing elective total hip arthroplasty

BACKGROUND

The sensitivity and the specificity of different methods to detect periprosthetic infection have been questioned. The current study aimed to investigate the kinetics of C-reactive protein (CRP) and procalcitonin (PCT) in patients undergoing uncomplicated elective total hip arthroplasty (THA), to provide a better interpretation of their levels in noninfectious inflammatory reaction.

METHODS

A total of 51 patients were included. Serum CRP and PCT concentrations were obtained before surgery, on the 1st, 3rd, and 7th postoperative days and after discharge on the 14th and 30th days and at 2 years.

RESULTS

Both markers were confirmed to increase after surgery. The serum CRP showed a marked increase on the 3rd postoperative day while the peak of serum PCT was earlier, even if much lower, on the first day. Then, they declined slowly approaching the baseline values by the second postoperative week. PCT mean values never exceed concentrations typically related to bacterial infections.

CONCLUSIONS

CRP is very sensitive to inflammation. It could be the routine screening test in the follow-up of THA orthopaedic patients, but it should be complemented by PCT when there is the clinical suspicion of periprosthetic infection.

Can procalcitonin be an accurate diagnostic marker for the classification of diabetic foot ulcers?

BACKGROUND

The differentiation of infected diabetic foot ulcers (IDFU) from non infected diabetic foot ulcers (NIDFU) is a challenging issue for clinicians.

OBJECTIVES

Recently, procalcitonin (PCT) was introduced as a remarkable inflammatory marker. We aimed to evaluate the accuracy of PCT in comparison to other inflammatory markers for distinguishing IDFU from NIDFU.

MATERIALS AND METHODS

We evaluated PCT serum level as a marker of bacterial infection in patients with diabetic foot ulcers. Sixty patients with diabetic foot ulcers were consecutively enrolled in the study. A total of 30 patients were clinically identified as IDFU by an expert clinician, taking as criteria for purulent discharges or at least two of manifestations of inflammation including warmth, redness, swelling and pain.

RESULTS

Procalcitonin, white blood cells (WBCs), erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP), were found significantly higher in the IDFU group compared to the NIDFU group. The best cut-off value, sensitivity and specificity were 40.5 mm/h, 90% and 94% for ESR, 7.1 mg/dL, 80% and 74% for CRP, 0.21, 70% and 74% for PCT, and 7.7×10(9)/L, 66% and 67% for WBCs, respectively. The area under the receiver operating characteristic curve for ESR was the greatest (0.967; P < 0.001), followed by CRP (0.871; P < 0.001), PCT (0.729; P < 0.001), and finally WBCs (0.721; P = 0.001).

CONCLUSIONS

These results suggest that PCT can be a diagnostic marker in combination with other markers like ESR and CRP to distinguish infected from non-infected foot ulcers, when clinical manifestations are un specific. Additional research is needed before the routine usage of PCT to better define the role of PCT in IDFU.

Analysis of synovial inflammatory markers to differ infectious from gouty arthritis

OBJECTIVES

Septic and gouty arthritis show the same clinical symptoms, but septic arthritis is an orthopedic emergency and needs immediate surgical intervention, whereas a systemic drug therapy is needed in acute gouty arthritis. The aim of this study was to investigate which inflammatory markers allow an accurate differentiation of septic and gouty arthritis.

DESIGN AND METHODS

This was a retrospective examination of serum markers (peripheral white blood cells, C-reactive Protein and uric acid) and inflammatory markers in the synovial fluid (lactate, glucose, uric acid, lactate dehydrogenase, synovial fluid white blood cell count, total protein, and interleukin-6) in 53 patients with culture-verified septic arthritis and 29 with gouty arthritis. Receiver-Operating-Characteristic-curves with corresponding Area under the curve (AUC), sensitivity, specificity, likelihood-ratio and interval likelihood-ratios were calculated to define the diagnostic potential of the inflammatory markers.

RESULTS

Synovial lactate showed the greatest diagnostic potential (AUC = 0.901, sensitivity = 89.5%, specificity = 77.3%, negative likelihood-ratio = 0.14) followed by synovial glucose (AUC=0.853) and synovial uric acid (AUC = 0.841).

CONCLUSIONS

Lactate in the synovial fluid has excellent diagnostic potential to differ septic arthritis from gouty arthritis. Synovial lactate levels above 10 mmol/L almost proofed septic arthritis, lactate levels lower than 4.3 mmol/L make it very unlikely.

Novel biomarkers to detect infection in revision hip and knee arthroplasties

BACKGROUND

A periprosthetic joint infection is one of the most challenging complications associated with THA and TKA. In the diagnostic process for detecting a periprosthetic joint infection, one of the most important steps is analysis of laboratory infection biomarkers.

QUESTIONS/PURPOSES

We investigated the sensitivity and specificity of the biomarkers procalcitonin, interleukin 6 (IL-6), and interferon α (IFN-α) as compared with conventional biomarkers (C-reactive protein [CRP], leukocyte level) for a periprosthetic joint infection associated with revision arthroplasties.

METHODS

We prospectively included and analyzed 84 patients (124 revision arthroplasties). The blood parameters of interest were procalcitonin, IL-6, IFN-α, leukocyte level, and CRP. Samples were taken preoperatively and on the first, third, and seventh postoperative days. The sensitivity and specificity of these biomarkers then were calculated.

RESULTS

Considering the preoperative values of 84 patients (124 operations), procalcitonin, IL-6, CRP, and leukocyte level correlated with periprosthetic joint infection, whereas IFN-α did not. A procalcitonin cut-off level of 0.35 ng/mL revealed a sensitivity of 80% and specificity of 37%. An IL-6 cut-off level of 2.55 pg/mL had a sensitivity of 92% and specificity of 59%.

CONCLUSIONS

In this study procalcitonin and IL-6 were helpful for detecting periprosthetic joint infections in revision arthroplasties, although CRP generally was superior. Procalcitonin and IL-6 may be considered adjuvant tests when the diagnosis of a periprosthetic joint infection is in doubt. This study showed, in addition to conventional biomarkers such as CRP and leukocyte level, procalcitonin and IL-6 were helpful for detecting infections associated with revision arthroplasties.

Serum Procalcitonin is a sensitive and specific marker in the diagnosis of septic arthritis and acute osteomyelitis

BACKGROUND

Early diagnosis of Acute Osteomyelitis (OM) and Septic Arthritis (SA) is of vital importance to avoid devastating complications. There is no single laboratory marker which is sensitive and specific in diagnosing these infections accurately. Total Count, ESR and CRP are not specific as they can also be elevated in non pyogenic causes of inflammation. Pus Culture and sensitivity is not a true gold standard due to its varied positivity rates (40 - 70%). Serum Procalcitonin (PCT), at 0.5 ng/ml is found to be an accurate marker for pyogenic infections. The objectives of this study were to show that PCT is an accurate marker in differentiating Acute Osteomyelitis and Septic Arthritis from viral and non infective inflammatory bone and joint conditions.

METHODS

Patients of all age groups (n = 82) with suspected Acute Osteomyelitis and Septic Arthritis were prospectively included in this study. All patients were subjected to TC, CRP, PCT, IgM Dengue, IgM Chikungunya, pus and blood culture and sensitivity. At the end of the study, patients were classified into 3 groups: Group 1 = Confirmed Pyogenic (n = 27); Group 2 = Presumed Pyogenic (n = 21); Group 3 = Non - infective inflammatory (n = 34).

RESULTS

Group 1 has higher mean PCT levels than Group 2 and 3 (p < 0.05). PCT, at 0.4 ng/ml, was 85.2% sensitive and 87.3% specific in diagnosing Septic Arthritis and Acute Osteomyelitis. In comparison, PCT at conventional cut - off of 0.5 ng/ml is 66.7% sensitive and 91% specific.

CONCLUSION

Serum Procalcitonin, at a cut - off of 0.4 ng/ml, is a sensitive and specific marker in the diagnosis of Septic Arthritis and Acute Osteomyelitis.

[Etiology and classification of septic coxitis]

Septic coxitis is a rare disesase which can be caused by a variety of pathogens. Primary and secondary coxitis can be differentiated depending on the etiology. In the initial stages the diagnosis is difficult but a delay in making the correct diagnosis or delayed therapy can result in fatal consequences for the patient, therefore, therapy should be started even in cases of suspected septic coxitis. Septic coxitis is classified into four stages depending on the arthroscopic findings. The best results are usually achieved by a combination of arthroscopic lavage and antibiotic therapy.

Use of procalcitonin in patients on chronic hemodialysis: procalcitonin is not related with increased serum calcitonin

Objectives. To investigate whether procalcitonin (PCT) could be useful for detecting bacterial infections in patients on hemodialysis (HD) and with increased calcitonin (CT). Methods. This prospective study included 42 males and 34 females on HD. The infection group consisted of 15 patients with proven bacterial infections; the other 61 patients were designated as the noninfection group. Serum C-reactive protein (CRP), interleukin (IL)-6, white blood cell (WBC) count, immature and total neutrophil (I/T) ratio, and CT were measured at the beginning of HD, and serum PCT levels at the beginning of HD and after HD. Results. The mean CT level in the both groups was apparently higher than that of nonchronic kidney disease. Significantly higher values between the infection and noninfection groups were seen for CRP, IL-6, WBC, I/T ratio, PCT, and CT. The PCT value of the area under the receiver operating characteristic curve was 0.921, which was significantly higher than the values for CRP (0.853; P < 0.01), IL-6 (0.739; P < 0.01), WBC (0.692; P < 0.01), and I/T ratio (0.584; P < 0.01). Conclusions. PCT was useful marker of bacterial infection in patients on HD and with increased CT. PCT levels should be determined before HD.

Evidence-based diagnostics: adult septic arthritis

BACKGROUND

Acutely swollen or painful joints are common complaints in the emergency department (ED). Septic arthritis in adults is a challenging diagnosis, but prompt differentiation of a bacterial etiology is crucial to minimize morbidity and mortality.

OBJECTIVES

The objective was to perform a systematic review describing the diagnostic characteristics of history, physical examination, and bedside laboratory tests for nongonococcal septic arthritis. A secondary objective was to quantify test and treatment thresholds using derived estimates of sensitivity and specificity, as well as best-evidence diagnostic and treatment risks and anticipated benefits from appropriate therapy.

METHODS

Two electronic search engines (PUBMED and EMBASE) were used in conjunction with a selected bibliography and scientific abstract hand search. Inclusion criteria included adult trials of patients presenting with monoarticular complaints if they reported sufficient detail to reconstruct partial or complete 2 × 2 contingency tables for experimental diagnostic test characteristics using an acceptable criterion standard. Evidence was rated by two investigators using the Quality Assessment Tool for Diagnostic Accuracy Studies (QUADAS). When more than one similarly designed trial existed for a diagnostic test, meta-analysis was conducted using a random effects model. Interval likelihood ratios (LRs) were computed when possible. To illustrate one method to quantify theoretical points in the probability of disease whereby clinicians might cease testing altogether and either withhold treatment (test threshold) or initiate definitive therapy in lieu of further diagnostics (treatment threshold), an interactive spreadsheet was designed and sample calculations were provided based on research estimates of diagnostic accuracy, diagnostic risk, and therapeutic risk/benefits.

RESULTS

The prevalence of nongonococcal septic arthritis in ED patients with a single acutely painful joint is approximately 27% (95% confidence interval [CI] = 17% to 38%). With the exception of joint surgery (positive likelihood ratio [+LR] = 6.9) or skin infection overlying a prosthetic joint (+LR = 15.0), history, physical examination, and serum tests do not significantly alter posttest probability. Serum inflammatory markers such as white blood cell (WBC) counts, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) are not useful acutely. The interval LR for synovial white blood cell (sWBC) counts of 0 × 10(9)-25 × 10(9)/L was 0.33; for 25 × 10(9)-50 × 10(9)/L, 1.06; for 50 × 10(9)-100 × 10(9)/L, 3.59; and exceeding 100 × 10(9)/L, infinity. Synovial lactate may be useful to rule in or rule out the diagnosis of septic arthritis with a +LR ranging from 2.4 to infinity, and negative likelihood ratio (-LR) ranging from 0 to 0.46. Rapid polymerase chain reaction (PCR) of synovial fluid may identify the causative organism within 3 hours. Based on 56% sensitivity and 90% specificity for sWBC counts of >50 × 10(9)/L in conjunction with best-evidence estimates for diagnosis-related risk and treatment-related risk/benefit, the arthrocentesis test threshold is 5%, with a treatment threshold of 39%.

CONCLUSIONS

Recent joint surgery or cellulitis overlying a prosthetic hip or knee were the only findings on history or physical examination that significantly alter the probability of nongonococcal septic arthritis. Extreme values of sWBC (>50 × 10(9)/L) can increase, but not decrease, the probability of septic arthritis. Future ED-based diagnostic trials are needed to evaluate the role of clinical gestalt and the efficacy of nontraditional synovial markers such as lactate.

Serum procalcitonin in systemic autoimmune diseases--where are we now?

OBJECTIVES

To review the current evidence regarding the value of measuring procalcitonin (PCT) levels in patients with systemic autoimmune diseases, with a focus on the evidence for diagnostic and analytical performance of this biomarker. A brief description of the pathophysiological basis of this biomarker is also included.

METHODS

Using PubMed from the National Library of Medicine, relevant English literature on PCT in patients with different systemic autoimmune diseases, from 1990 to 2009, was reviewed. The search used keywords referring to procalcitonin and systemic lupus erythematosus, antineutrophil cytoplasmic antibody-associated systemic vasculitis, Goodpasture syndrome, rheumatoid arthritis, and giant cell arteritis.

RESULTS

When used in the appropriate clinical setting, the measurement of serum PCT levels is valuable as a marker of severe systemic bacterial and fungal infections and sepsis. Information regarding plasma PCT levels in patients with active underlying systemic autoimmune diseases is limited, primarily from observational studies and case series, with considerable variability of patient characteristics and clinical settings. In the detection of systemic infection concomitant with autoimmune diseases, PCT had a diagnostic sensitivity of 53 to 100% and a specificity of 84 to 97% (depending on the selection criteria) and was superior to other inflammatory markers tested. Most of the studies used a semiquantitative test for PCT measurement (functional assay sensitivity <0.5 ng/mL), which can explain the low sensitivity of the test. PCT levels were not significantly affected by renal function abnormalities or immunosuppressive agents. Although high PCT levels commonly occurred with infection, elevated levels of PCT could be found in patients with vasculitis without evidence of infection, often correlated with high disease activity scores.

CONCLUSIONS

Significantly elevated PCT levels offer good specificity and sensitivity for systemic infection in patients with systemic autoimmune diseases, regardless of the use of corticosteroids or immunosuppressive agents. PCT measurement may add to diagnostic accuracy in patients with systemic autoimmune diseases who present with a febrile illness, especially when highly sensitive PCT assays and specific PCT cutoff ranges are used in a predefined clinical setting (reflecting the likelihood of infection versus an autoimmune disease flare). However, there are limitations when using this biomarker in patients with systemic autoimmune diseases. PCT levels should not replace the necessary extensive diagnostic workup, which should include a thorough history and physical examination, combined with appropriate immunological, microbiological, radiological, and histological data.