Scandinavian Journal of Infectious Diseases, 2014; 46: 745–752

ORIGINAL ARTICLE

Scand J Infect Dis Downloaded from informahealthcare.com by Ondokuz Mayis Univ. on 11/08/14 For personal use only.

Procalcitonin better than C-reactive protein, erythrocyte sedimentation rate, and white blood cell count in predicting DNAemia in patients with sepsis

CHRISTIAN LELI1, ANGELA CARDACCIA1, MARTA FERRANTI1, ANGELICA CESARINI1, FRANCESCO D’ALÒ1, CARLA FERRI2, ELIO CENCI1 & ANTONELLA MENCACCI1 From the 1Microbiology Section, Department of Experimental Medicine, University of Perugia, Santa Maria della Misericordia Hospital and 2Department of Clinical Chemistry and Haematology; Santa Maria della Misericordia Hospital, Perugia, Italy

Abstract Background: Procalcitonin (PCT) levels can be used to predict bacteremia and DNAemia in patients with sepsis. In this study, the diagnostic accuracy of PCT in predicting blood culture (BC) results and DNAemia, as detected by real-time PCR (RT-PCR), was compared with that of other markers of inflammation commonly evaluated in patients with suspected sepsis, such as C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and white blood cell (WBC) count. Methods: A total of 571 patients for whom BC, blood RT-PCR, PCT, CRP, ESR, and WBC count were requested for laboratory diagnosis of sepsis were included in the study. Receiver operating characteristic curve analysis was performed to compare the ability of the above biomarkers to predict BC and blood RT-PCR results. Results: A total of 108 pathogens were identified by BC (79 pathogens, 14.5% positive rate) and/or RT-PCR (90 pathogens, 16.5% positive rate), after exclusion of 26 contaminated samples. The PCT areas under the curve (AUCs) in predicting BC (0.843; 95% CI 0.796–0.890; p ⬍ 0.0001) and RT-PCR (0.916; 95% CI 0.888-0.945; p ⬍ 0.0001) results were significantly greater than AUCs found for CRP, ESR, and WBC count. Conclusions: PCT showed a better diagnostic accuracy than CRP, ESR, and WBC count in predicting DNAemia and bacteremia in patients with suspected sepsis.

Keywords: procalcitonin, sepsis, real-time PCR, C-reactive protein, erythrocyte sedimentation rate

Introduction Sepsis, a systemic deleterious host response to infection that leads to organ dysfunction [1], is a major cause of morbidity and mortality [2]. Rapid diagnosis and therapeutic interventions are desirable to improve the overall survival in septic patients [3]. Blood culture (BC) is considered the gold standard for detection of pathogens from patients with sepsis [1], although not always providing time-critical results [4]. Besides BC, specific biomarkers and molecular diagnostic assays [5] have been developed for rapid laboratory diagnosis and to improve clinical management of sepsis. Among these, blood real-time PCR (RT-PCR) has been shown to provide rapid reliable results, unaffected by ongoing antimicrobial

therapy [6–8], and to possess a diagnostic accuracy in pathogen detection even better than BC [9]. In fact, unlike BC, RT-PCR can detect not only viable microorganisms, but also circulating bacterial DNA, which can persist in a patient’s blood for several days after completion of successful antimicrobial therapy [10,11], or released into the bloodstream from the primary infectious focus [12]. During recent years, many biomarkers have been evaluated and compared to find the best predictor of sepsis [13]. Among these, procalcitonin (PCT) has been identified as having an optimal diagnostic accuracy for predicting bacteremia in different clinical settings [14,15], representing an advance over Creactive protein (CRP) or other widely used markers,

Correspondence: Prof. Antonella Mencacci MD, Microbiology Section, Department of Experimental Medicine, University of Perugia; Santa Maria della Misericordia Hospital, Sant’Andrea delle Fratte, Piazzale Menghini 1, 06132, Perugia, Italy. Tel: ⫹39 075 578 4285. Fax: ⫹39 075 578 4298. E-mail: antonella. [email protected] (Received 29 March 2014 ; accepted 3 June 2014 ) ISSN 0036-5548 print/ISSN 1651-1980 online © 2014 Informa Healthcare DOI: 10.3109/00365548.2014.936493

Scand J Infect Dis Downloaded from informahealthcare.com by Ondokuz Mayis Univ. on 11/08/14 For personal use only.

746

C. Leli et al.

such as erythrocyte sedimentation rate (ESR), in burned patients [16] or in adult patients with acute fever [17]. Recently, it has been reported that PCT can predict RT-PCR results in patients with suspected sepsis [18], suggesting that this marker can be useful to predict DNAemia in these patients. The aim of this study was to compare the diagnostic accuracy of PCT with those of other markers of inflammation commonly used in clinical practice, such as CRP, ESR, and white blood cell (WBC) count, to predict bacteremia and DNAemia in patients with suspected sepsis.

BACTEC Plus bottles were used for patients under antibiotic therapy and standard bottles for untreated patients. Two sets from two different sites were collected at the same time. The bottles were incubated in a BACTEC FX automated blood culture system (Becton Dickinson). All bottles flagged positive were removed from the instrument and an aliquot was taken for Gram stain and subculture on solid media for subsequent analysis. Identification of microorganisms was performed with conventional methods and with the Phoenix automatic system (Becton Dickinson).

Materials and Methods

Blood real-time PCR

Patients and samples

Blood RT-PCR was carried out by means of the SeptiFast (SF) kit (Roche Diagnostics GmbH, Mannheim, Germany), according to the manufacturer’s instructions. Briefly, a 3 ml K-EDTA blood sample was collected, and 1.5 ml was processed for DNA extraction and PCR testing as described previously [8]. After mechanical lysis, DNA was extracted using the SF Prep kit MGRADE (Roche Diagnostics), as described by the manufacturer. Hybridization probes were used. An internal extraction and amplification control, included in the kit, was introduced into each specimen during the first steps of the extraction procedure. A negative control supplied by the manufacturer was included in each extraction series. Using the LightCycler SF kit MGRADE, real-time PCR was performed in a LightCycler 2.0 instrument (Roche Diagnostics). Three different primer mixes were used to amplify Gram-positive bacteria, Gram-negative bacteria, and fungi. The internal transcribed spacer region was the specific target for the detection of bacterial and fungal pathogens. Reagent controls provided in the kit were used as the positive control in the PCRs. The emitted fluorescence was measured in one of the four different detection channels (610, 640, 670, and 705 nm). Species identification (melting temperature analysis of specimens and controls in each channel) and report generation were obtained using the SF identification software SIS (Roche Diagnostics). The microorganisms identified by SF have been listed elsewhere [20]. The analytical sensitivity of the assay ranged between 3 and 100 cells/ml, depending on the individual microorganisms [20].

This retrospective study was performed using clinical and routine laboratory data collected from the Clinical Microbiology Unit of the General Hospital of Perugia, Italy, from January 2013 to October 2013, from 571 patients. Inclusion criteria were: (i) the presence of two or more diagnostic criteria for systemic inflammatory response syndrome (SIRS) and suspected or documented infection [19]; (ii) blood samples for BC, RT-PCR, PCT, CRP, ESR, and WBC count, collected simultaneously during the same septic episode. For each patient, only samples collected during the first septic episode were considered. Exclusion criteria were: (i) absence of at least two SIRS criteria [19], (ii) lack of at least one of the above samples, (iii) samples not drawn simultaneously from the same patient. PCT, CRP, ESR, and WBC count determination PCT levels were measured in sera via the automatic analyzer VIDAS B.R.A.H.M.S (bioMérieux, Marcy L’Etoile, France), according to the manufacturer’s instructions. The lower limit of detection of the assay was 0.05 ng/ml and the functional assay sensitivity was 0.09 ng/ml (VIDAS B.R.A.H.M.S. PCT package insert; bioMérieux). Plasma CRP levels were measured using the latex-enhanced CRP assay (Dade Behring High Sensitivity CRP Assay, Marburg, Germany), ESR was assessed by means of the Test-1 automated analyzer (Alifax SPA, Padova, Italy), and WBC count was determined by means of the automatic cell counter (SYSMEX XT-1800; DASIT, Milan, Italy). Blood culture For each sample, an aliquot of 5–10 ml whole blood was inoculated into BACTEC aerobic and anaerobic bottles (Becton Dickinson, Sparks, MD, USA).

Definition of pathogen Microorganisms detected by BC and/or blood RT-PCR were considered to be true pathogens, based on data from patients’ medical records, according to the following conditions. (1) Microorganisms identified by BC and RT-PCR coincided and were reported

Scand J Infect Dis Downloaded from informahealthcare.com by Ondokuz Mayis Univ. on 11/08/14 For personal use only.

PCT predicts DNAemia in septic patients as the cause of the episode of sepsis in the medical records. (2) Microorganisms detected by only one of the two tests (BC or RT-PCR) coincided with the results of culture from samples from the suspected infectious foci, collected from the same patient during the same infectious episode. (3) Microorganisms detected by only one test belonged to a species generally accepted as common etiologic agents of the patient’s type of infection. (4) Microorganisms detected by only one test were considered pathogens, if reported as the cause of the episode of sepsis in the final diagnosis, based on clinical, instrumental, and laboratory data. Coagulase-negative staphylococci and other skin commensals were considered contaminants when isolated from only one set of BC [21], and in the absence of clinical and/or laboratory data suggesting their pathogenic role. Statistical analysis SPSS statistical package, release 13.0 (SPSS Inc., Chicago, IL, USA) was used for all statistical analyses. Values are expressed as median and interquartile range (IQR) or count and percentage. Comparisons of continuous variables were assessed by the Mann– Whitney U test. The McNemar test was used for testing the differences between paired proportions. Evaluation of diagnostic performance for discriminating blood RT-PCR and BC results was performed using receiver operating characteristic (ROC) curves. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated. Statistical significance was assumed if a null hypothesis could be rejected at a p value of ⱕ 0.05. Ethics statement Samples were collected as part of standard care and those included in the database were de-identified before access. No personal information was stored in the study database. No patient intervention occurred with the obtained results. The manuscript does not contain clinical studies or patient data. For these reasons the study was exempt from the Institutional Review Board.

Results Samples for BC, blood RT-PCR, PCT, CRP, ESR, and WBC counts from 571 patients with suspected sepsis were included in the study. Table I summarizes patients’ characteristics and laboratory data of the whole study population and the subgroups of patients in which the causative agent of sepsis was identified by BC or RT-PCR.

747

Blood culture and RT-PCR concordant results were obtained in 498 (87.2%) patients: 437 were concordant negative and 61 were concordant positive. Twenty-six contaminated samples, 1 blood RT-PCR (0.2%), and 25 BCs (4.4%), were excluded from subsequent analyses, which were ultimately performed on 545 patients. In all, 108 pathogens were identified by RT-PCR and/or BC (Table II). No polymicrobial infection was observed. Real-time PCR results were positive for a pathogen in 90 (16.5%) patients, and BC in 79 (14.5%). No significant difference was found between the two methods in the rate of pathogen detection (p ⫽ 0.145). The median serum PCT value was significantly higher in RT-PCR-positive versus RT-PCR-negative patients and in BC-positive versus BC-negative patients (Table I). Elevated values were observed both in patients with concordant BC- and RTPCR-positive results and in patients with only RTPCR-positive results (Table II). Median serum CRP, ESR, and WBC counts were significantly higher in RT-PCR-positive versus RT-PCR-negative patients, but not in BC-positive versus BC-negative patients (Table I). The PCT median value of BC positive for a pathogen was significantly higher than that of contaminated BC (7.5 ng/ml (IQR 1.6–31.5) vs 0.2 ng/ml (IQR 0.07–0.7), p ⬍ 0.0001). A comparison of PCT median values between pediatric patients (median age 3 years, IQR 1–10) and adults showed no significant difference (0.38 ng/ml (IQR 0.2–2.4) vs 0.41 ng/ml (0.1–2.3), p ⫽ 0.615). ROC analysis, performed to assess the diagnostic accuracy along with sensitivity, specificity, PPV, and NPV of the best cut-off values of the different biomarkers in predicting RT-PCR and BC results are shown in Figure 1. PCT had the best accuracy in predicting RT-PCR and BC results, at the cutoff value of ⱖ 0.5 ng/ml (94% sensitivity and 64% specificity). The other markers were predictive of RT-PCR results, even if with a low diagnostic accuracy, but not of BC results (Figure 1). ROC analysis performed to evaluate the discriminatory ability of PCT for differentiating the concordant positive group (RT-PCR-positive/BC-positive) from the concordant negative one showed an AUC of 0.921 (95% confidence interval (CI) 0.890–0.953), p ⬍ 0.0001. A multivariate ROC curve analysis, aimed to determine the overall accuracy of the combination of the four biomarkers, showed AUCs of 0.799 (95% CI 0.757–0.840; p ⬍ 0.0001) for RT-PCR results and 0.735 (95% CI 0.681–0.790; p ⫽ 0.001) for BC results; thus lower than AUCs of PCT alone (Figure 1).

Whole study population (n ⫽ 571)

19 16 68 65 15 66 334

3 6 14 9 5 8 75

51.5 (IQR 28.3–76) 11.8 (IQR 5.3–17.3) 8.9 (IQR 2.5–46)

42 (IQR 23–65) 7.7 (IQR 3.2–14.9) 0.3 (IQR 0.1–0.9)

11 315 (IQR 6685–16 795) 9885 (IQR 6865–14 010)

(4.2%) (3.5%) (14.9%) (14.3%) (3.3%) (14.5%) (73.4%)

408 (89.6%) 43 (9.4%) 4 (0.9%)

80 (88.9%) 7 (7.8%) 3 (3.3%) (3.3%) (6.7%) (15.6%) (10.0%) (5.6%) (8.9%) (83.3%)

69 (IQR 53–81) 271 (84.2%)

Negative (n ⫽ 455)

77 (IQR 65–84) 51 (56.7%)

Positive for a pathogen (n ⫽ 90)

0.05 0.004 ⬍ 0.0001

0.05

0.71 0.16 0.88 0.27 0.29 0.15 0.05

0.84 – –

0.17 0.61

p value

(5.1%) (7.6%) (12.7%) (17.7%) (6.3%) (10.1%) (79.7%)

18 16 72 60 15 66 346

(3.9%) (3.4%) (15.5%) (12.9%) (3.2%) (14.2%) (74.2%)

417 (89.5%) 45 (9.7%) 4 (0.9%)

69 (IQR 53–81) 277 (59.4%)

Negative (n ⫽ 466)

49 (IQR 25.2–70) 10.9 (IQR 3.6–15.4) 7.5 (IQR 1.6–31.5)

42 (IQR 23–66) 7.7 (IQR 3–14.6) 0.2 (IQR 0.1–1.1)

11 230 (IQR 6320–17 510) 9860 (IQR 6860–13 955)

4 6 10 14 5 8 63

71 (89.9%) 5 (6.3%) 3 (3.8%)

78 (IQR 67–84) 45 (57%)

Positive for a pathogen (n ⫽ 79)

Patients with BC results (n ⫽ 545)

0.26 0.14 ⬍ 0.0001

0.17

0.61 0.09 0.52 0.24 0.17 0.33 0.3

0.07 – –

0.12 0.67

p value

CRP, C-reactive protein; ESR, erythrocyte sedimentation rate; IQR, interquartile range; PCT, procalcitonin. aIn all, 264 (52.0%) patients were in Internal Medicine, 90 (17.7%) in Gastroenterology, 51 (10.0%) in Infectious Disease Unit, 31 (6.1%) in Cardiology, 29 (5.7%) in Pediatrics, 15 (3.0%) in Nephrology, 8 (1.6%) in Occupational Medicine, 8 (1.6%) in Oncology, 6 (1.2%) in Bone Marrow Transplant Unit, 5 (1.0%) in Neurology, and 1 (0.1%) in Dermatology. bSixteen (28.6%) patients were in Cardiac Surgery, 10 (17.9%) in General Surgery, 8 (14.2%) in Neurosurgery, 7 (12.5%) in Vascular Surgery, 5 (8.9%) in Urology, 4 (7.1%) in Obstetrics, 3 (5.4%) in Oncologic Surgery, 2 (3.6%) in Orthopedics, and 1 (1.8%) in Otorhinolaryngology. cValues are expressed as median (IQR).

Demographics Median age (years) 71 (IQR 54–82) Males 335 (58.7 %) Ward of hospitalization Medical 508 (89.0%)a Surgical 56 (9.8%)b Intensive care unit 7 (1.2%) Relevant comorbidities Malignancy 24 (4.2%) Chronic lung disease 25 (4.4%) Diabetes 87 (15.2%) Chronic renal failure 79 (13.8) Chronic liver disease 23 (4%) Immunosuppression 77 (13.5%) Ongoing antimicrobial 421 (73.7%) therapy Laboratory datac Leukocytes 10 005 (IQR 6855.5–14 330) (cells/mm3) ESR (mm/h) 43 (IQR 24–67) CRP (mg/dl) 8.3 (IQR 3.3–15.2) PCT (ng/ml) 0.4 (IQR 0.1–2.3)

Characteristic

Patients with RT-PCR results (n ⫽ 545)

Table I. Clinical and laboratory characteristics of the patients enrolled in the study.

Scand J Infect Dis Downloaded from informahealthcare.com by Ondokuz Mayis Univ. on 11/08/14 For personal use only.

748 C. Leli et al.

PCT predicts DNAemia in septic patients

749

Table II. Patients with pathogen detected by real-time PCR and/or blood culture and corresponding median PCT levels.

Scand J Infect Dis Downloaded from informahealthcare.com by Ondokuz Mayis Univ. on 11/08/14 For personal use only.

No. of patients with pathogen identified by Pathogen (total no. of patients)

Real-time PCR only

Blood culture only

Both methods

Escherichia coli (33) Staphylococcus aureus (24) Klebsiella pneumoniae/oxytoca (11) Pseudomonas aeruginosa (6) Streptococcus spp.a (7) Streptococcus pneumoniae (5) Enterobacter cloacae/aerogenes (5) Enterococcus faecium (3) Proteus mirabilis (3) Enterococcus faecalis (2) Candida albicans (2) Candida glabrata (1) Subtotal (102) Bacteroides fragilis (1) Citrobacter koseri (1) Salmonella typhi (1) Providencia rettgeri (1) Porphyromonas spp. (1) Morganella morganii (1) Total(108) Median PCT level (ng/ml)

12 7 0 2 1 2 2 1 0 1 1 0 29 NDc ND ND ND ND ND 29 8.5 (IQR 3.4–62.6)d

3 3 0 1 2b 0 0 1 1 0 0 1 12 1 1 1 1 1 1 18 0.6 (IQR 0.3–7.2)

18 14 11 3 4 3 3 1 2 1 1 0 61 0 0 0 0 0 0 61 10.4 (IQR 2.3–39.7)

IQR, interquartile range; PCT, procalcitonin. aStreptococcus spp. group includes S. agalactiae, S. pyogenes, S. anginosus, S. bovis, S. constellatus, S. cristatus, S. gordonii, S. intermedius, S. milleri, S. mitis, S. mutans, S. oralis, S. parasanguinis, S. salivarius, S. sanguinis, S. thermophilus, S. vestibularis, S. viridans. bStreptococcus bovis; Streptococcus gallolyticus. cND, not detectable by the real-time PCR assay. dValues are expressed as median (IQR).

Discussion Sepsis is a major cause of morbidity and mortality [2], and the outcome can be significantly improved by rapid diagnosis and therapeutic interventions [3]. Current research focuses on several biomarkers and molecular methods to be employed in addition to BC for rapid diagnosis of sepsis [5,13]. When interpreted in the context of clinical and laboratory data, PCT can be helpful for early diagnosis of sepsis and for predicting a bacteremia documented by BC [14], performing better than other biomarkers of inflammation [17,22,23], including CRP [17,24]. It has been suggested that PCT should be included in the diagnostic and therapeutic algorithms for management of sepsis [15] or other infections, such as community-acquired pneumonia with serious adverse events [25]. A recent review of the diagnostic accuracy of PCT in respiratory tract infections highlights that advanced molecular diagnostics, more specific and sensitive than conventional methods, should be used to validate the ability of this marker to discriminate viral from bacterial infections [26]. It is conceivable that, also for sepsis diagnosis, the evaluation of PCT accuracy could be influenced by the diagnostic

method (RT-PCR or BC) used for the etiological diagnosis of the infection. The RT-PCR system used in the present study is the more intensively investigated molecular method for diagnosis of sepsis. It is considered a valuable diagnostic tool, to be used in combination with and not as a replacement for BC [8,20,27–29]. Indeed, the comparison of RT-PCR with BC clearly showed that the two methods do not always provide identical results for the same septic episode, due to the different targets (microbial DNA or viable microorganisms) detected by the two tests. A previous study in an unselected population of 1009 patients with fever and suspected sepsis demonstrated that PCT can predict RT-PCR results (AUC ⫽ 0.927) [18], suggesting that this marker can be useful to predict DNAemia in patients with sepsis. The present study, while confirming previous findings [18], shows that, as for bacteremia detected by conventional culture method, PCT is better than CRP, ESR, and WBC count also in predicting DNAemia, with the best diagnostic accuracy being found at the cut-off of ⱖ 0.5 ng/ml, with 94% sensitivity and 64% specificity. These findings are in line with other studies using conventional culture methods to evaluate PCT

Scand J Infect Dis Downloaded from informahealthcare.com by Ondokuz Mayis Univ. on 11/08/14 For personal use only.

750

C. Leli et al.

Figure 1. Receiver operating characteristic (ROC) curves for real-time PCR (RT-PCR) and blood culture (BC) results along with sensitivities, specificities, positive predictive values (PPV), negative predictive values (NPV), at the best cut-offs of the following parameters: procalcitonin (PCT), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and white blood cell (WBC) count.

diagnostic accuracy in sepsis diagnosis. In different clinical settings, PCT has been found to perform better than CRP, ESR, and WBC count in discerning between bacterial or nonbacterial causes of fever [17,22,30]. In a study of 60 burned patients, Barati et al. found that PCT was better than CRP, ESR, WBC count and neutrophil counts in predicting bacteremia with an AUC of 0.97, and a PCT level ⬎ 0.5 ng/ml was highly predictive of infection, with 100% sensitivity and 83.3% specificity [16]. Likewise, in a population of 539 adult patients admitted to an emergency department (ED) with suspected infection, PCT, compared with CRP, emerged as the best marker for severe sepsis [23]. Similar results were also observed by Müller et al. in a population of 925 patients with definite diagnosis of community-acquired pneumonia [31]. That study found AUCs of 0.82 for PCT, 0.67 for CRP, and 0.58 for WBC. Likewise, van Nieuwkoop et al. observed an AUC of 0.81 for PCT in diagnosing bacteremia in a population of 581 patients suffering from febrile urinary tract infection [32]. In the present study it was found that PCT median values of patients with BC positive for a pathogen were significantly higher than those of patients with contaminated BC. These results are in

line with those of Schuetz et al., showing that PCT can discriminate between blood contamination and bloodstream infection due to coagulase-negative staphylococci [33]. Nevertheless, the rationale of the present study was based on the fact that clinical interpretation of positive DNAemia is different from that of culturepositive bacteremia [12]. In fact, RT-PCR can also be positive for a pathogen when the corresponding BC is negative, especially in antibiotic-treated patients [8,34,35]. Indeed, a great percentage (73.7%) of our patient population was under antibiotic therapy during sampling. Thus, the finding that increased PCT levels were associated with positive RT-PCR results suggests that, in septic patients, DNAemia could have the same diagnostic and clinical significance as bacteremia. In the present study, a statistically significant diagnostic accuracy in predicting RT-PCR results was found for CRP ⱖ 7.8 mg/dl (AUC ⫽ 0.599; p ⫽ 0.004), for ESR ⱖ 35 mm/h (AUC 0.568; p ⫽ 0.047), and for WBC count ⱖ 13 500 cells/mm3 (AUC 0.573; p ⫽ 0.035). Nevertheless, the corresponding AUCs were much lower than those for PCT, and the multivariate ROC curve analysis combining the four biomarkers together did not

Scand J Infect Dis Downloaded from informahealthcare.com by Ondokuz Mayis Univ. on 11/08/14 For personal use only.

PCT predicts DNAemia in septic patients show any improvement in the diagnostic accuracy in comparison to PCT alone. Indeed, the difference between PCT and CRP diagnostic accuracy may rely on differences in their kinetics and pathophysiological pathways [36–39]. In this line, it has been demonstrated that, in febrile ED patients, CRP determined within 12 h from fever onset was not reliable in distinguishing bacteremic from nonbacteremic infections, while CRP was slightly useful (AUC 0.64) when determined after 12 h from fever onset [40]. Likewise, Barati et al. [16] found a poor diagnostic accuracy of both WBC count and ESR for diagnosis of sepsis in burn cases, as these markers are influenced not only by inflammation and infection but also by other confounding variables [38]. It is conceivable that the better accuracy observed for CRP, ESR, and WBC count in predicting RTPCR but not BC results could be explained by the better diagnostic performance of the molecular test in comparison with culture. However, these results could have been influenced by the high proportion of patients in this study who had been pretreated with antibiotics, in whom RT-PCR has proven more sensitive than BC [8,34,35]. Indeed, the lack of biomarker levels adjustment for antibiotic pretreatment represents a limitation of the study, as for relevant comorbidities. Indeed, PCT levels can also be elevated after surgery, cardiogenic shock, heat shock, acute graft-versus-host disease, and immunotherapy such as granulocyte transfusion, which could limit its usefulness as a sepsis biomarker [41]. In addition, we were unable to compare the diagnostic accuracy of PCT with that of other biomarkers of sepsis, such as interleukin-6 (IL-6), IL-8, triggering receptor expressed on myeloid cells 1, and others. Given that PCT increases during the first 6 h of infection [22,37], it would have been interesting to analyze our results in the light of the time intervals between the onset of symptoms and BC and RTPCR sample collection, but due to the retrospective nature of study these data were not available. Another possible confounding factor could be the inclusion in the study of 29 pediatric patients. Nevertheless, the comparison of PCT median values between pediatric patients and adults showed no significant difference. This is probably due to the small number of children included in the study, their median age (3 years, IQR 1–10), and the fact that all patients were over 6 months of age (data not shown) [30]. In addition, a ROC analysis performed after exclusion of the pediatric population gave results not significantly different from those obtained in whole population (data not shown). Again, because of the retrospective nature of the study, possible confounders and a certain selection bias cannot be excluded.

751

In conclusion, this study showed that the diagnostic accuracy of PCT in predicting DNAemia in patients with sepsis was superior to that of CRP, ESR, and WBC count. The association of CRP, ESR, and WBC count with PCT in predicting RT-PCR results did not seem to improve PCT diagnostic accuracy. Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

References [1] Dellinger RP, Levy MM, Rhodes A, Annane D, Gerlach H, Opal SM, et al. Surviving Sepsis Campaign Guidelines Committee including The Pediatric Subgroup. Surviving Sepsis Campaign: international guidelines for management of severe sepsis and septic shock, 2012. Intensive Care Med 2013;39:165–228. [2] Mayr FB,Yende S, Angus DC. Epidemiology of severe sepsis. Virulence 2014;5:4–11. [3] Bloos F, Reinhart K. Rapid diagnosis of sepsis. Virulence 2014;5:154–60. [4] Bauer M, Reinhart K. Molecular diagnostics of sepsis–where are we today? Int J Med Microbiol 2010;300:411–13. [5] Reinhart K, Bauer M, Riedemann NC, Hartog CS. New approaches to sepsis: molecular diagnostics and biomarkers. Clin Microbiol Rev 2012;25:609–34. [6] Yanagihara K, Kitagawa Y, Tomonaga M, Tsukasaki K, Kohno S, Seki M, et al. Evaluation of pathogen detection from clinical samples by real-time polymerase chain reaction using a sepsis pathogen DNA detection kit. Crit Care 2010;14:R159. [7] Obara H, Aikawa N, Hasegawa N, Hori S, Ikeda Y, Kobayashi Y, et al. The role of a real-time PCR technology for rapid detection and identification of bacterial and fungal pathogens in whole-blood samples. J Infect Chemother 2011;17:327–33. [8] Pasqualini L, Mencacci A, Leli C, Montagna P, Cardaccia A, Cenci E, et al. Diagnostic performance of a multiple realtime PCR assay in patients with suspected sepsis hospitalized in an internal medicine ward. J Clin Microbiol 2012; 50:1285–8. [9] Herne V, Nelovkov A, Kütt M, Ivanova M. Diagnostic performance and therapeutic impact of LightCycler SeptiFast assay in patients with suspected sepsis. Eur J Microbiol Immunol (Bp) 2013;3:68–76. [10] Navarro E, Segura JC, Castaño MJ, Solera J. Use of real-time quantitative polymerase chain reaction to monitor the evolution of Brucella melitensis DNA load during therapy and post-therapy follow-up in patients with brucellosis. Clin Infect Dis 2006;42:1266–73. [11] Øvstebø R, Brandtzaeg P, Brusletto B, Haug KB, Lande K, Høiby EA, et al. Use of robotized DNA isolation and realtime PCR to quantify and identify close correlation between levels of Neisseria meningitidis DNA and lipopolysaccharides in plasma and cerebrospinal fluid from patients with systemic meningococcal disease. J Clin Microbiol 2004; 42:2980–7. [12] Peters RP, van Agtmael MA, Gierveld S, Danner SA, Groeneveld AB, Vandenbroucke-Grauls CM, et al. Quantitative detection of Staphylococcus aureus and Enterococcus

752

[13]

[14]

[15]

[16]

Scand J Infect Dis Downloaded from informahealthcare.com by Ondokuz Mayis Univ. on 11/08/14 For personal use only.

[17]

[18]

[19]

[20]

[21]

[22]

[23]

[24]

[25]

[26]

C. Leli et al. faecalis DNA in blood to diagnose bacteremia in patients in the intensive care unit. J Clin Microbiol 2007;45:3641–6. Kibe S, Adams K, Barlow G. Diagnostic and prognostic biomarkers of sepsis in critical care. J Antimicrob Chemother 2011:66:ii33–40. Riedel S. Procalcitonin and the role of biomarkers in the diagnosis and management of sepsis. Diagn Microbiol Infect Dis 2012;73:221–7. Schuetz P, Albrich W, Mueller B. Procalcitonin for diagnosis of infection and guide to antibiotic decisions: past, present and future. BMC Med 2011;9:107. Barati M, Alinejad F, Bahar MA, Tabrisi MS, Shamshiri AR, Bodouhi NO, et al. Comparison of WBC, ESR, CRP and PCT serum levels in septic and non-septic burn cases. Burns 2008;34:770–4. Chirouze C, Schuhmacher H, Rabaud C, Gil H, Khayat N, Estavoyer JM, et al. Low serum procalcitonin level accurately predicts the absence of bacteremia in adult patients with acute fever. Clin Infect Dis 2002;35:156–61. Mencacci A, Leli C, Cardaccia A, Meucci M, Moretti A, D’Alò F, et al. Procalcitonin predicts real-time PCR results in blood samples from patients with suspected sepsis. PLoS One 2012;7:e53279. Bone RC, Balk RA, Cerra FB, Dellinger RP, Fein AM, Knaus WA, et al. ACCP/SCCM Consensus Conference Committee. Definitions for sepsis and organ failure and guidelines for the use of innovative therapies in sepsis. The ACCP/SCCM Consensus Conference Committee. American College of Chest Physicians/Society of Critical Care Medicine. 1992. Chest 2009;136:e28. Lehmann LE, Hunfeld KP, Emrich T, Haberhausen G, Wissing H, Hoeft A, et al. A multiplex real-time PCR assay for rapid detection and differentiation of 25 bacterial and fungal pathogens from whole blood samples. Med Microbiol Immunol 2008;197:313–24. Weinstein MP. Blood culture contamination: persisting problems and partial progress. J Clin Microbiol 2003; 41:2275–8. Limper M, de Kruif MD, Duits AJ, Brandjes DP, van Gorp EC. The diagnostic role of procalcitonin and other biomarkers in discriminating infectious from non-infectious fever. J Infect 2010;60:409–16. Uusitalo-Seppälä R, Koskinen P, Leino A, Peuravuori H, Vahlberg T, Rintala EM. Early detection of severe sepsis in the emergency room: diagnostic value of plasma C-reactive protein, procalcitonin, and interleukin-6. Scand J Infect Dis 2011;43:883–90. Jeong S, Park Y, Cho Y, Kim HS. Diagnostic utilities of procalcitonin and C-reactive protein for the prediction of bacteremia determined by blood culture. Clin Chim Acta 2012;413:1731–6. Schuetz P, Suter-Widmer I, Chaudri A, Christ-Crain M, Zimmerli W, Mueller B. Procalcitonin-Guided Antibiotic Therapy and Hospitalization in Patients with Lower Respiratory Tract Infections (ProHOSP) Study Group. Prognostic value of procalcitonin in community-acquired pneumonia. Eur Respir J 2011;37: 384–92. Gilbert DN. Procalcitonin as a biomarker in respiratory tract infection. Clin Infect Dis 2011;52:S346–50.

[27] Lehmann LE, Hunfeld KP, Steinbrucker M, Brade V, Book M, Seifert H, et al. Improved detection of blood stream pathogens by real-time PCR in severe sepsis. Intensive Care Med 2010;36:49–56. [28] Chang SS, Hsieh WH, Liu TS, Lee SH, Wang CH, Chou HC, et al. Multiplex PCR system for rapid detection of pathogens in patients with presumed sepsis a systemic review and meta-analysis. PLoS One 2013; 8:e62323. [29] Paolucci M, Stanzani M, Melchionda F, Tolomelli G, Castellani G, Landini MP, et al. Routine use of a real-time polymerase chain reaction method for detection of bloodstream infections in neutropaenic patients. Diagn Microbiol Infect Dis 2013;75:130–4. [30] Simon L, Gauvin F, Amre DK, Saint-Louis P, Lacroix, J. Serum procalcitonin and C-reactive protein levels as markers of bacterial infection: a systematic review and meta-analysis. Clin Infect Dis 2004;39:206–17. [31] Müller F, Christ-Crain M, Bregenzer T, Krause M, Zimmerli W, Mueller B, et al.; ProHOSP Study Group. Procalcitonin levels predict bacteremia in patients with community-acquired pneumonia: a prospective cohort trial. Chest 2010;138:121–9. [32] van Nieuwkoop C1, Bonten TN, van’t Wout JW, Kuijper EJ, Groeneveld GH, Becker MJ, et al. Procalcitonin reflects bacteremia and bacterial load in urosepsis syndrome: a prospective observational study. Crit Care 2010;14: R206. [33] Schuetz P, Mueller B, Trampuz A. Serum procalcitonin for discrimination of blood contamination from bloodstream infection due to coagulase-negative staphylococci. Infection 2007;35:352–5. [34] Lucignano B, Ranno S, Liesenfeld O, Pizzorno B, Putignani L, Bernaschi P, et al. Multiplex PCR allows rapid and accurate diagnosis of bloodstream infections in newborns and children with suspected sepsis. J Clin Microbiol 2011;49:2252–8. [35] Vince A, Lepej SZ, Barsi B, Dusek D, Mitrovic´ Z, Serventi-Seiwerth R, et al. LightCycler SeptiFast assay as a tool for the rapid diagnosis of sepsis in patients during antimicrobial therapy. J Med Microbiol 2008;57:1306–7. [36] Monneret G, Labaune JM, Isaac C, Bienvenu F, Putet G, Bienvenu J. Procalcitonin and C-reactive protein levels in neonatal infections. Acta Paediatr 1997;86:209–12. [37] Dandona P, Nix D, Wilson MF, Aljada A, Love J, Assicot M, et al. Procalcitonin increase after endotoxin injection in normal subjects. J Clin Endocrinol Metab 1994; 79:1605–8. [38] Brunkhorst FM, Heinz U, Forycki ZF. Kinetics of procalcitonin in iatrogenic sepsis. Intensive Care Med 1998;24: 888–9. [39] Kim KE, Han JY. Evaluation of the clinical performance of an automated procalcitonin assay for the quantitative detection of bloodstream infection. Korean J Lab Med 2010;30: 153–9. [40] Lee CC, Hong MY, Lee NY, Chen PL, Chang CM, Ko WC. Pitfalls in using serum C-reactive protein to predict bacteremia in febrile adults in the ED. Am J Emerg Med 2012;30:562–9. [41] Cho SY, Choi JH. Biomarkers of sepsis. Infect Chemother 2014;46:1–12.

Procalcitonin better than C-reactive protein, erythrocyte sedimentation rate, and white blood cell count in predicting DNAemia in patients with sepsis.

Procalcitonin (PCT) levels can be used to predict bacteremia and DNAemia in patients with sepsis. In this study, the diagnostic accuracy of PCT in pre...
237KB Sizes 0 Downloads 4 Views