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Korean J Clin Microbiol Vol. 14, No. 1, March, 2011 DOI: 10.5145/KJCM.2011.14.1.7 The Value of Serum Procalcitonin Level for Differentiation between Contaminants and Pathogens in Bacteremia Hei Kyung Jin 1, Jae Yun Jang 1, Young Uh 1, Ohgun Kwon 1, Kap Jun Yoon 1, Hyo Youl Kim 2, Young Keun Kim 2 Departments of 1 Laboratory Medicine and 2 Infectious Diseases, Yonsei University Wonju College of Medicine, Wonju, Korea Background: Bacteremia is a life-threatening infection, and prognosis is highly dependent on early recognition and treatment with appropriate antimicrobial agents. We investigated the diagnostic performance of serum procalcitonin (PCT) for differentiation between contaminants and true pathogens in blood cultures. Methods: Serum PCT, C-reactive protein (CRP) and blood culture were performed for 473 patients between February 2008 and October 2008. We retrospectively reviewed the patients' clinical characteristics and laboratory results based on medical records. Results: The mean concentration of PCT was significantly different between the two negative and positive blood culture groups (6.45 ng/ml vs 28.77 ng/ ml, P<0.001). Procalcitonin levels were found to be markedly higher in those with Gram-negative bacilli (mean±sd; 59.58±67.00 ng/ml) bacteremia than in those with Gram-positive cocci (mean±sd; 17.75±42.88 ng/ml) bacteremia (P<0.001). The areas under the receiver operating characteristic curves (95% confidence interval) for PCT and CRP were 0.880 (0.820 0.940) and 0.637 (0.538 0.736), respectively. The use of a PCT level of 2 ng/ml as a cutoff value yielded an 83.6% positive predictive value and a 77.4% negative predictive value for the detection of bacteremia pathogens. Conclusion: Serum PCT is a helpful diagnostic marker for rapidly and accurately distinguishing between contaminants and pathogens in blood cultures. (Korean J Clin Microbiol 2011;14:7-12) Key Words: Procalcitonin, Blood culture, Bacteremia, Contamination 서 균혈증에의한사망률은환자의연령, 선행질환의종류와중증정도, 장기기능장애, 중환자실입원등의요인에의해영향을받으며 [1], 원인균의종류에따라서도차이가있다 [2]. 균혈증환자에서부적절한경험적항균제치료는예후에나쁜영향을주게되며 [3], 혈액배양위양성은재원기간의연장과의료비용의증가를초래할수있다. 균혈증의예후는조기진단과이에따른적절한항균제치료에큰영향을받는다 [4]. 균혈증의검사실진단은혈액배양이기본이며, 보조적인진단법으로혈액내의세균유전자나항원을검출하는방법과세균감염에의해인체가반응하여생성하는물질을측정하는간 Received 4 May, 2010, Revised 28 June, 2010 Accepted 20 July, 2010 Correspondence: Young Uh, Department of Laboratory Medicine, Yonsei University Wonju College of Medicine, 161 Ilsan-dong, Wonju 220-701, Korea. (Tel) 82-33-741-1592, (Fax) 82-33-731-0506, (E-mail) u931018@yonsei.ac.kr 론 접적인방법으로구분할수있다. 혈액배양은균혈증의확진방법이지만세균의동정결과를얻기까지는최소한 2 3일이상의시간이필요하다. 세균의유전자를검출하는방법은이론적으로는가장예민도가높고신속한방법이지만시약이고가이며단계별검사과정이수작업에의존하므로통상검사로사용하기어렵다. 혈액내미생물의항원이나항체를검출하는방법은신속한결과를얻을수있으나예민도가낮고특정원인균에만적용이가능하다. C-반응성단백 (CRP) 도균혈증의진단에이용될수있으나특이도가낮은단점이있다. 최근에개발된 procalcitonin (PCT) 은혈중내의농도가전신염증과세균감염의심한정도와밀접한연관성이있는것으로알려져있으며 [5], 원인균종별로도혈중농도의차이가있는것으로알려져있다 [4]. 이에본연구에서는혈액에서분리된균종의그람양성과음성세균및효모균의균종별 PCT의혈중농도를분석하였으며, PCT와 CRP의패혈증의객관적인진단표지자로서의유용성을평가하였다. 7

8 Korean J Clin Microbiol 2011;14(1):7-12 대상및방법 2008년 2월부터 10월까지혈청 PCT와혈액배양이의뢰되었던환자들을대상으로혈청 CRP 검사를동시에시행하였다. PCT 는 VIDAS (biomérieux Co., Lyon, France) 장비에서 BRAHMS PCT 시약을이용하여효소연관형광검사법으로정량측정하였으며측정범위는 0.05 200 ng/ml이고, CRP는 MODULAR SYSTEMS (Roche Diagnostics, Bazel, Switzerland) 에서면역비탁법으로정량측정하였으며측정범위는 0.03 350 mg/dl이다. 혈액배양은 BACTEC 9240 system (Becton Dickinson, NJ, USA) 과 BacT/Alert 3D system (biomérieux, Durham, NC, USA) 의두가지자동화장비를이용하여 5일간배양하였다. 대상환자의임상정보와검사결과는의무기록을토대로 PCT가의뢰된시점으로부터 24시간이내의결과만을분석하였다. 전신염증반응증후군 (systemic inflammatory response syndrome, SIRS) 은 SIRS 4가지기준 (1 체온이 38 o C를초과하거나 36 o C 미만일때 2 심박수가분당 90회를초과할때 3 호흡수가분당 20회를초과하거나동맥혈이산화탄소분압 (PaCO 2) 이 32 mmhg 미만일때 4 백혈구수가 12,000/mm 3 를초과하거나 4,000/mm 3 미만또는백혈구감별계산에서미성숙중성구가 10% 를초과할때 ) 에서두가지이상을포함할경우로하였다 [6]. PCT 결과는다섯구간 (<0.05, 0.05 0.49, 0.5 1.99, 2 9.99, 10) 으로나누어 CRP 결과와의평균과표준편차를비교ㆍ분석하였다 [7]. 혈액배양결과에따라양성군과음성군으로나누었고, 혈액배양양성군에서 Bacillus spp., Corynebacterium spp., Propionibacterium spp., coagulase-negative staphylococci 등이한개의배양병에서만분리되면오염균, 오염균으로분류한균종이두개이상의배양병에서동일하게분리되면가능성있는병인균, 이외의경우는병인균으로해석하였다 [8]. 혈액배양결과와 SIRS를기준으로 PCT과 CRP의평균과표준편차를비교ㆍ분석하였다. PCT과 CRP의균혈증의진단적유용성을비교해보고자상대수행능곡선을구하여곡선아래면적을비교하였다. 통계적분석에서연속형변수는 t-test를이용하였고, 범주형변수는 χ 2 test를적용하였으며, 3군이상의평균치비교에는분산분석을사용하였다. 통계분석은 SPSS (Microsoft Co., USA) 프로그램을이용하였고, 통계적유의수준은 P <0.05를기준으로판단하였다. 결과 PCT 검사를시행한 473명검체의결과분포는 0.05 ng/ml 미만은 12.3% 로가장적었으며, 0.05 0.49 ng/ml 구간이 25.8% 로가장많았고, 0.5 1.99 ng/ml 구간, 2 9.99 ng/ml Table 1. C-reactive protein levels and positive rate of blood culture according to the five groups of procalcitonin concentrations Procalcitonin groups (ng/ml) No. (%) Mean±SD Range No. (%) of positive blood culture I (<0.05) 58 (12.3) 3.58±4.10* 0.01 17.52 9 (15.5) II (0.05 0.49) 122 (25.8) 9.58±7.54 0.01 31.26 22 (18.0) III (0.5 1.99) 114 (24.1) 13.28±10.10 0.03 41.52 22 (19.3) IV (2 9.99) 83 (17.5) 16.17±10.25 0.12 46.20 21 (25.3) V ( 10) 96 (20.3) 20.02±11.34 0.17 50.80 46 (47.9) Total 473 (100) 13.02±10.54 0.01 50.80 120 (25.4) *P<0.0001 (between group I and II V); P=0.002 (between group II and III), P<0.0001 (between group II and IV V); P=0.05 (between group III and IV), P<0.0001 (between group III and V); P<0.0001 (between group IV and V). Table 2. Procalcitonin and C-reactive protein levels according to blood culture and SIRS results Blood culture No. (%) Procalcitonin (ng/ml) Mean±SD (range) Mean±SD (range) Negative 353 (74.6) 6.45±17.61 (<0.05 184.72) 12.53±10.43 (0.01 50.80) SIRS + 160 (33.8) 6.99±19.04 (<0.05 184.72) 12.62±11.31 (0.01 50.80) SIRS 193 (40.8) 6.01±16.36 (<0.05 134.08) 12.46±9.68 (0.01 46.20) Positive 120 (25.4) 28.77±52.54 (<0.05 200.00)* 14.45±10.73 (0.01 49.37) SIRS + 61 (12.9) 41.18±58.50 (<0.05 200.00) 14.89±11.13 (0.33 40.92) SIRS 59 (12.5) 15.95±42.34 (<0.05 200.00) 14.00±10.41 (0.01 49.37) *P<0.0001 (between blood culture negative and positive group); P=0.008 (between SIRS positive and SIRS negative group among the blood culture positive group).

Hei Kyung Jin, et al. : Procalcitonin Level in Bacteremia 9 구간, 10 ng/ml 구간은각각 24.1%, 17.5% 와 20.3% 였다. PCT I에서 V 구간의혈액배양양성률은각각 15.5%, 18.0%, 19.3%, 25.3%, 47.9% 로 PCT 농도가증가함에따라혈액배양 양성률도증가하였다 (Table 1). PCT 다섯구간에서 CRP 결과를비교하였을때, 각구간에서의 CRP 결과 ( 평균과표준편차 ) 는각각 3.58±4.10 mg/dl, 9.58±7.54 mg/dl, 13.28±10.10 mg/dl, Table 3. Procalcitonin and C-reactive protein levels according to organisms isolated from blood culture Organisms No. (%) Procalcitonin (ng/ml) Mean±SD (range) Mean±SD (range) Gram-positive cocci 68 (57.5) 17.75±42.88 (<0.05 200.00) 13.43±10.89 (0.10 49.37) Aerococcus viridans 1 (0.8) 200 11.85 Enterococcus faecalis 1 (0.8) 176.87 24.98 Enterococcus faecium 2 (1.7) 94.11±133.04 9.80±7.13 Micrococcus kristinae 1 (0.8) 19.46 17.20 Micrococcus luteus 1 (0.8) 0.75 7.93 Staphylococcus aureus 9 (7.5) 17.02±34.04 13.76±8.54 Staphylococcus capitis 3 (2.5) 0.25±0.31 9.80±9.11 Staphylococcus cohnii 1 (0.8) 0.77 27.66 Staphylococcus epidermidis 20 (16.7) 8.88±27.97 9.44±9.63 Staphylococcus haemolyticus 3 (2.5) 2.09±2.26 11.25±10.34 Staphylococcus hominis 16 (13.3) 3.04±6.75 12.95±12.74 Staphylococcus kloosii 1 (0.8) 1.18 25.81 Staphylococcus lentus 1 (0.8) 1.93 1.79 Staphylococcus lugduenesis 1 (0.8) 11.19 29.57 Staphylococcus saprophyticus 1 (0.8) 0.21 7.44 Staphylococcus warneri 1 (0.8) 21.46 18.28 Streptococcus, β-hemolytic group G 1 (0.8) 35.58 40.92 Streptococcus pneumoniae 3 (2.5) 36.15±27.18 24.48±11.92 Streptococcus sanguis 1 (0.8) 54.51 18.73 Gram-negative bacilli 35 (29.2) 59.58±67.00* (<0.05 200.00) 17.86±10.74 (0.40 37.15) Bacteroides fragilis 1 (0.8) 21.97 8.64 Bordetella bronchiseptica 1 (0.8) 0.82 1.17 Enterobacter cloacae 1 (0.8) 0.79 10.26 Escherichia coli 19 (15.8) 53.70±54.07 18.19±11.02 Klebsiella oxytoca 1 (0.8) 24.31 28.16 Klebsiella pneumoniae 8 (6.7) 111.41±92.41 16.15±10.05 Morganella morganii 2 (1.7) 46.96±65.76 20.47±9.59 Proteus mirabilis 1 (0.8) 18.97 35.32 Salmonella group D 1 (0.8) 12.95 25.83 Gram-positive rod (GPR) 8 (5.8) 1.87±4.09 (<0.05 11.12) 9.38±5.38 (0.55 16.26) Bacillus species 1 (0.8) 0.92 16.26 Bacillus licheniformis 1 (0.8) 0.26 13.19 Bacillus pumilus 1 (0.8) 11.12 6.71 Bacillus subtilis 1 (0.8) 0.16 13.75 Corynebacterium bovis 2 (1.7) 0.28±0.34 3.65±4.38 Unidentified GPR 1 (0.8) 0.04 8.44 Anaerobic GPR 1 (0.8) 17.43 18.54 Yeast species 5 (4.2) 14.44±15.48 (0.70 32.32) 9.97±8.47 (0.57 23.62) Candida albicans 2 (1.7) 15.25 15.09±12.06 Candida parapsilosis 2 (1.7) 20.24 9.55±0.35 Saccharomyces cerevisiae 1 (0.8) 1.24 0.57 Polymicrobial 4 (3.3) 14.52±20.28 (<0.05-44.11) 16.69±12.71 (5.64 34.70) E. faecalis, S. epidermidis 1 (0.8) 0.04 15.82 E. faecium, S. haemolyticus 1 (0.8) 11.14 10.59 S. epidermidis, S. hominis 1 (0.8) 44.11 34.70 Corynebacterium spp., S. haemolyticus 1 (0.8) 2.81 5.64 *P<0.0001 (between gram-negative bacilli and gram-positive cocci).

10 Korean J Clin Microbiol 2011;14(1):7-12 16.17±10.25 mg/dl와 20.02±11.34 mg/dl로서 PCT I구간은 II V 구간, PCT II 구간은 III V 구간, PCT III 구간은 PCT IV와 V 구간, PCT IV 구간은 PCT V 구간과통계적으로유의한차이가있었다 (Table 1). 혈액배양음성군의 PCT와 CRP의평균과표준편차는 6.45± 17.61 ng/ml와 12.53±10.43 mg/dl 였고, 양성군은 28.77±52.54 ng/ml와 14.45±10.73 mg/dl로서 PCT는혈액배양양성에서음성군보다통계적으로유의하게높았으나 CRP는차이가없었다 (Table 2). 혈액배양양성군에서 SIRS 음성군의 PCT와 CRP의평균과표준편차는 15.95±42.34 ng/ml와 14.00±10.41 mg/dl 였고, SIRS 양성군은 41.18±58.50 ng/ml와 14.89±11.13 mg/dl 로서 PCT는 SIRS 양성군이음성군보다통계적으로유의하게높았으나 CRP는차이가없었다 (Table 2). 균분류에따른 PCT와 CRP의평균과표준편차는그람음성 막대균이 59.58±67.00 ng/ml와 17.86±10.74 mg/dl, 그람양성알균 17.75±42.88 ng/ml와 13.43±10.89 mg/dl, 효모균 14.44± 15.48 ng/ml와 9.97±8.47 mg/dl, 그람양성막대균 1.87±4.09 ng/ml와 9.38±5.38 mg/dl으로서 PCT는그람음성막대균이그람양성알균보다통계적으로유의하게높았으나 CRP는차이가없었다 (Table 3). 혈액배양결과판독기준에따라오염균에서의 PCT와 CRP 의평균과표준편차는 1.62±3.01 ng/ml와 10.06±7.92 mg/dl, 가능성있는병인균은 3.29±6.60 ng/ml와 14.01±12.27 mg/dl였고, 병인균에서는 49.05±62.62 ng/ml와 16.65±10.89 mg/dl로서 PCT와 CRP 모두오염균과가능성있는병인균에서는통계적으로유의한차이가없었으나오염균과병인균간에는차이가있었다 (Table 4). 상대수행능곡선분석에서균혈증의병인균에대한 PCT의곡선아래면적은 0.880로서 95% 신뢰구간은 0.820 0.940이었고, 예민도와특이도가모두높은판정기준치 (cutoff value) 는 2.07 ng/ml이었다. CRP의균혈증의병인균에대한상대수행능곡선의곡선아래면적은 0.637로서 95% 신뢰구간은 0.538 0.736이었다 (Fig. 1). 균혈증의병인균에대한 PCT 판정기준치를 0.5 ng/ml, 2 ng/ml, 10 ng/ml와 25 ng/ml로설정했을때의진단적효율성지표는 Table 5와같았다. 고 찰 Fig. 1. Relative operating characteristic curves of procalcitonin and C-reactive protein. 혈액배양에서분리된균종을오염균과병인균으로정확히감별하는것은신속한진단과치료를가능하게하여불필요한재원기간을줄일수있기때문에환자와의료진모두에게매 Table 4. Procalcitonin and C-reactive protein levels according to contaminants and pathogens in blood cultures Organisms No. (%) Procalcitonin (ng/ml) Mean±SD (range) Mean±SD (range) Contaminants 32 (26.7) 1.62±3.01 (<0.05 13.29) 10.06±7.92 (0.01 27.66) Probable pathogen 20 (16.7) 3.29±6.60 (<0.05 25.16) 14.01±12.27 (0.09 49.37) Pathogen 68 (56.6) 49.05±62.62 (0.24 200.00) *, 16.65±10.89 (0.07 40.92) *P=0.002 (between probable pathogen and pathogen group); P<0.0001 (between contaminants and pathogen group). Table 5. Diagnostic performance of procalcitonin according to cutoff values for discrimination of pathogen of bacteremia Procalcitonin cutoff values (ng/ml) Sensitivity (%) Specificity (%) Positive predictive value (%) Negative predictive value (%) Efficiency (%) 0.05 98.5 17.3 60.9 90.0 63.3 0.5 92.6 50.0 70.8 83.9 74.2 2 82.4 78.8 83.6 77.4 80.8 10 60.3 90.4 89.1 63.5 73.3 25 41.2 98.1 96.6 56.0 65.8

Hei Kyung Jin, et al. : Procalcitonin Level in Bacteremia 11 우중요하다. 1990년대를전후로여러요인에의한면역기능저하환자의증가로인하여병원성이약한균종들도패혈증을유발하게되었고이에따라혈액배양결과해석이더욱어려워지고있다. 혈액배양오염을없애기위해서는철저한무균적피부천자가선행되어야하지만혈액배양은의뢰건수가매우많고 2 3회반복채혈을하므로응급실과같은바쁜상황에서는원칙대로채혈하지못할수있다. 또한, 환자의감염상태가심각할때는한번채혈하여 2 3개의혈액배양병에접종할수있기때문에동일균종이 2 3개의배양병에서분리되었어도피부상재균일수있다. 혈액배양에서분리된균종의유전자를검출하는방법도오염균과병인균을감별하기어렵기는마찬가지이다. 환자의임상정보를토대로감염유무를평가하는 SIRS와 acute physiology and chronic health evaluation (APACHE) 점수, 감염에반응하여인체가생성한물질을측정하는것은피부오염균에의한결과해석의문제점을보완할수있다. 그러나 SIRS나 APACHE 점수는주로임상적소견에근거한지표이므로주관적인판정이내포될수있기때문에객관적인표지자가요구된다. 염증과감염의객관적인표지자검사로는백혈구수와분획, delta neutrophil index, CRP, fibrin degradation product, D-dimer, tumor necrosis factor-α, interleukin-6 등이있으며 [9,10] 최근에는 PCT의유용성에대한연구보고가증가하고있다. PCT는 calcitonin의전구물질로서갑상선의 C 세포에서생성되며, 정상인에서는 0.1 ng/ml 미만의농도이지만세균과진균의감염증과균혈증등에서증가하여 2.0 ng/ml 이상의농도는패혈증과패혈성쇼크의고위험군이다 [5,9]. 염증이발생하면일반적으로 1시간이내에호중구와단구가동원되면서각종시토카인들이분비되고, 4 6시간후부터 PCT과 CRP가증가하기시작하여, CRP는 36시간정도경과한후에최고치에도달하는데비해 PCT는 8시간경에최고치에도달하고 24시간가량지속하는차이점이있다 [5,9,11]. 또한 PCT는 CRP와는달리주로세균감염에서높게증가하므로전신성염증반응과패혈증의검출, 감별및추적에유용한것으로보고되고있다 [4,5,7,9,11,12]. 허등 [7] 은혈액배양음성군과양성군에서 PCT 와 CRP 모두가통계적으로유의한차이가있음을보고하였으나본결과에서는 PCT 농도만유의한차이가있었다. 본연구에서혈액배양음성군에서의 PCT 평균농도는 6.45 ng/ml로서전신감염이상의농도에해당하는경우가많았기때문에 PCT 양성결과만으로혈액배양음성과양성을예측할수는없을것으로생각되었다. Charles 등 [4] 은그람음성과그람양성세균에의한균혈증에서 PCT의평균값은각각 71.27 ng/ml과 16.85 ng/ml로서 PCT 판정기준치를 16.0 ng/ml 설정하면그람음성세균에의한균혈증의양성과음성예측도는각각 83% 와 74% 로보고하였다. 본연구에서는그람염색에따른 PCT 평균농도는그람음성막 대균, 그람양성알균, 효모균및그람양성막대균의순이었으며, 그람양성막대균은 8균주중 2균주를제외하곤 PCT 농도가 1 ng/ml 미만이었고, 장알균, Aerococcus viridans, 연쇄알균은 PCT 농도가그람양성알균의평균농도보다높았다. 향후균종별 PCT 농도와의연관성에대한연구가필요할것으로생각되었다. 혈액배양오염균과병인균을감별하는 PCT 판정기준치를 2 ng/ml로설정하면양성과음성예측도가각각 83.6% 와 77.4% 였고, 0.05 ng/ml을기준으로하면음성예측도가 90.0% 였으며, 25 ng/ml을기준으로하면양성예측도가 96.6% 였다. 이러한진단적효율성지표값은오염균의정의, 대상군의설정방법, 분리된균종의분포, PCT 의뢰시기, 혈액배양에서의무균적채취와채취량등의다양한변수들에의해영향을받을수있기때문에체계적인전향적연구가필요하다. 본연구는후향적으로의무기록을분석하여 PCT의진단적효율성을분석한것이므로결과해석에주의가필요하며, 향후이러한문제점을보완한추가연구가이루어져야할것이다. 참고문헌 1. Angus DC, Linde-Zwirble WT, Lidicker J, Clermont G, Carcillo J, Pinsky MR. Epidemiology of severe sepsis in the United States: analysis of incidence, outcome, and associated costs of care. Crit Care Med 2001;29:1303-10. 2. Digiovine B, Chenoweth C, Watts C, Higgins M. The attributable mortality and costs of primary nosocomial bloodstream infections in the intensive care unit. Am J Respir Crit Care Med 1999;160: 976-81. 3. Ibrahim EH, Sherman G, Ward S, Fraser VJ, Kollef MH. The influence of inadequate antimicrobial treatment of bloodstream infections on patient outcomes in the ICU setting. Chest 2000;118: 146-55. 4. Charles PE, Ladoire S, Aho S, Quenot JP, Doise JM, Prin S, et al. Serum procalcitonin elevation in critically ill patients at the onset of bacteremia caused by either Gram negative or Gram positive bacteria. BMC Infect Dis 2008;8:38. 5. Christ-Crain M and Müller B. Procalcitonin in bacterial infectionshype, hope, more or less? Swiss Med Wkly 2005;135(31-32): 451-60. 6. American College of Chest Physicians/Society of Critical Care Medicine Consensus Conference: definitions for sepsis and organ failure and guidelines for the use of innovative therapies in sepsis. Crit Care Med 1992;20:864-74. 7. Hur M, Moon HW, Yun YM, Kim KH, Kim HS, Lee KM. Comparison of diagnostic utility between procalcitonin and C-reactive protein for the patients with blood culture-positive sepsis. Korean J Lab Med 2009;29:529-35. 8. Weinstein MP, Murphy JR, Reller LB, Lichtenstein KA. The clinical significance of positive blood cultures: a comprehensive analysis of 500 episodes of bacteremia and fungemia in adults. II. Clinical observations, with special reference to factors influencing prognosis. Rev Infect Dis 1983;5:54-70. 9. Müller B, Schuetz P, Trampuz A. Circulating biomarkers as surrogates for bloodstream infections. Int J Antimicrob Agents

12 Korean J Clin Microbiol 2011;14(1):7-12 2007;30 Suppl 1:S16-23. 10. Nahm CH, Choi JW, Lee J. Delta neutrophil index in automated immature granulocyte counts for assessing disease severity of patients with sepsis. Ann Clin Lab Sci 2008;38:241-6. 11. Hunziker S, Hügle T, Schuchardt K, Groeschl I, Schuetz P, Mueller B, et al. The value of serum procalcitonin level for differentiation of infectious from noninfectious causes of fever after orthopaedic surgery. J Bone Joint Surg Am 2010;92:138-48. 12. Charles PE, Ladoire S, Snauwaert A, Prin S, Aho S, Pechinot A, et al. Impact of previous sepsis on the accuracy of procalcitonin for the early diagnosis of blood stream infection in critically ill patients. BMC Infect Dis 2008;8:163. = 국문초록 = 균혈증에서오염균과병인균의감별을위한 Procalcitonin 의농도값 연세대학교원주의과대학 1 진단검사의학과, 2 감염내과진혜경 1, 장재윤 1, 어영 1, 권오건 1, 윤갑준 1, 김효열 2, 김영근 2 배경 : 균혈증은생명을위협하는위중한감염으로서조기진단과이에따른적절한항균제치료에의해예후가달라진다. 본연구에서는균혈증에서오염균과병인균의감별진단에서혈청 procalcitonin (PCT) 의진단적유용성을평가해보고자하였다. 방법 : 2008년 2월부터 10월까지 473명을대상으로혈청 PCT, C-reactive protein (CRP) 과혈액배양을시행하였고, 의무기록을토대로임상소견과검사결과를후향적으로분석하였다. 결과 : 혈액배양음성군과양성군의 PCT 농도의평균은각각 6.45 ng/ml와 28.77 ng/ml로서통계적으로유의한차이가있었다 (P<0.001). PCT 농도는그람음성막대균 ( 평균 ± 표준편차 ; 59.58±67.00 ng/ml) 균혈증에서그람양성알균 ( 평균 ± 표준편차 ; 17.75±42.88 ng/ml) 균혈증에비해월등히높았다 (P<0.001). 상대수행능곡선분석에서균혈증의병인균에대한 PCT와 CRP의곡선아래면적 (95% 신뢰구간 ) 은각각 0.880 (0.820 0.940) 과 0.637 (0.538 0.736) 였다. PCT 농도값 2 ng/ml 를판정기준치로하면병인균의양성예측도와음성예측도는각각 83.6% 와 77.4% 였다. 결론 : 혈청 PCT는혈액배양에서오염균과병인균을신속하고정확하게감별하는데도움을줄수있는유용한검사였다. [ 대한임상미생물학회지 2011;14:7-12] 교신저자 : 어영, 220-701, 강원도원주시일산동 161 원주기독병원진단검사의학과 Tel: 033-741-1592, Fax: 033-731-0506 E-mail: u931018@yonsei.ac.kr