Evaluation of Verigene Blood Culture Test Systems for Rapid Identification of Positive Blood Cultures.

The performance of molecular tests using the Verigene Gram-Positive and Gram-Negative Blood Culture nucleic acid tests (BC-GP and BC-GN, resp.; Naosphere, Northbrook, IL, USA) was evaluated for the identification of microorganisms detected from blood cultures. Ninety-nine blood cultures containing Gram-positive bacteria and 150 containing Gram-negative bacteria were analyzed using the BC-GP and BC-GN assays, respectively. Blood cultures were performed using the Bactec blood culture system (BD Diagnostic Systems, Franklin Lakes, NJ, USA) and conventional identification and antibiotic-susceptibility tests were performed using a MicroScan system (Siemens, West Sacramento, CA, USA). When a single strain of bacteria was isolated from the blood culture, Verigene assays correctly identified 97.9% (94/96) of Gram-positive bacteria and 93.8% (137/146) of Gram-negative bacteria. Resistance genes mecA and vanA were correctly detected by the BC-GP assay, while the extended-spectrum ß-lactamase CTX-M and the carbapenemase OXA resistance gene were detected from 30 cases cultures by the BC-GN assay. The BC-GP and BC-GN assays showed high agreement with conventional identification and susceptibility tests. These tests are useful for rapid identification of microorganisms and the detection of clinically important resistance genes from positive Bactec blood cultures.

Clonal and horizontal spread of the blaOXA-232 gene among Enterobacteriaceae in a Korean hospital.

All 16 Klebsiella pneumoniae isolates and both Escherichia coli isolates harbored the bla(OXA-232) and bla(CTX-M-15) genes. Furthermore, all 16 K. pneumoniae isolates belonged to a unique pulsed-field gel electrophoresis clone and were assigned to an identical sequence type (ST14). The 2 E. coli isolates were identified as ST131 and ST457. The bla(OXA-232) gene underwent horizontal transfer to E. coli isolates via a conjugative ColE-type plasmid. The introduction of this K. pneumoniae ST14 strain to the Korean hospital was attributed to an index patient who was likely colonized during a prior hospitalization in India.

Changes in the incidence of Streptococcus pneumoniae bacteremia and its serotypes over 10 years in one hospital in South Korea.

Here, we examined the distribution of pneumococcal serotypes and the antibiotic susceptibility of Streptococcus pneumoniae in clinical blood isolates. The serotypes of 91 S. pneumoniae blood isolates, collected from January 2003 to March 2014, were identified by multiplex PCR and sequencing. The most common serotypes were 19F, 19A, 3, 4, and 14, accounting for 53.8% of the total. The serotype coverage rates of pneumococcal conjugated vaccine (PCV) 7, PCV10, and PCV13 were different during three test periods: 38.7%, 70.9%, and 93.5% in period I (2003-2005), 46.8%, 50.0%, and 75.0% in period II (2006-2008), and 28.5%, 32.1%, and 64.2% in period III (2009-2014), respectively. By contrast, the number of non-PCV13 serotypes increased from 6.4% in period I to 25% and 35.7% in periods II and III, respectively. The susceptibility of non-PCV13 serotypes to antimicrobial agents (penicillin, erythromycin, cefotaxime, and meropenem) was higher than that of PCV serotypes. In particular, non-PCV13 serotypes showed 100% and 95% susceptibility to penicillin and cefotaxime, respectively. Serotypes 19A and 19F showed high prevalence (79.1%) among 24 multi-drug resistant (MDR) isolates. Notably, all serotype 19A isolates were MDR. From January 2003 to March 2014, the proportion of non-PCV13 serotype pneumococci in blood isolates increased whereas the coverage rate of PCV13 decreased. Effective pneumococcal vaccines are required to protect against MDR serotype 19A isolates and the increasing number of non-PCV13 serotypes.

Analysis of rotavirus genotypes in Korea during 2013: an increase in the G2P[4] genotype after the introduction of rotavirus vaccines.

BACKGROUND: Group A rotavirus is the leading cause of acute gastroenteritis in children worldwide. We investigated G and P genotypes of group A rotavirus strains isolated from patients during 2013 and investigated which genotypes were identified from vaccinated patients. METHODS: From January to December 2013, 2235 fecal specimens were tested for rotavirus antigen, of which 374 specimens (16.7%) showed positive results. Strains from 288 rotavirus-positive specimens were genotyped using PCR and sequencing, and individual patients' corresponding vaccine histories were investigated through the Korean Center for Disease Control website. RESULTS: G2 (22.6%) and P[4] (24.0%) were the most frequently identified G and P genotypes, respectively; accordingly, G2P[4] (19.8%) was the most prevalent G/P genotype observed in this period. G4P[6] (10.1%) was the second most prevalent G/P genotype and was mostly detected in neonates. Other genotypes, G1P[8], G9P[8], G1P[6], and G3P[6], were also detected. Of 288 rotavirus-positive specimens, 48 specimens were obtained from previously vaccinated patients. G2P[4] was also the genotype most frequently isolated from vaccinated patients. VP7 epitope analysis of G1P[8] and G2P[4] strains showed at least one amino acid differences in comparison with Rotarix and RotaTeq vaccine strains. The genotypic distribution of rotavirus strains in Korea has been shown temporal and geographical differences. CONCLUSION: This study showed that G2P[4] was the genotype most frequently isolated from both vaccinated and unvaccinated patients in Korea during 2013. However, it is unclear whether the change of predominant genotype is due to the effect of vaccination or due to natural variation.

Evaluation of an immunochromatographic assay for the rapid and simultaneous detection of rotavirus and adenovirus in stool samples.

BACKGROUND: We evaluated the analytical and clinical performances of the SD BIOLINE Rota/Adeno Rapid kit (SD Rota/Adeno Rapid; Standard Diagnostics, Inc., Korea), an immunochromatographic assay (ICA), for the simultaneous detection of rotaviruses and adenoviruses in human stool samples. METHODS: We tested 400 clinical stool samples from patients with acute gastroenteritis and compared the ICA results with the results obtained by using ELISA, enzyme-linked fluorescent assays (ELFA), PCR, and multiplex reverse transcription-PCR (mRT-PCR). To assess the analytical performance of the SD BIOLINE Rota/Adeno Rapid kit, we determined its detection limit, reproducibility, cross-reactivity, and analytical reactivity for adenovirus subtypes, and performed interference studies. RESULTS: The overall agreement rates among the tested methods were 91.5% for rotavirus and 85.5% for adenovirus. On the basis of mRT-PCR, the overall agreement, positive agreement, and negative agreement rates of the ICA were 95.6%, 100%, and 94.9% for rotavirus, and 94.0%, 71.4%, and 94.8% for adenovirus, respectively. Using the ICA, we detected all the subtypes of adenovirus tested, but the analytical reactivities for adenovirus subtypes were different between the 4 adenovirus detection methods. The high reproducibility was confirmed, and no cross-reactivity or interference was detected. CONCLUSIONS: The SD BIOLINE Rota/Adeno Rapid kit showed acceptable analytical and clinical performances. However, interpretation of adenovirus positive/negative result should be cautious because of different detectability for adenovirus subtypes among adenovirus detection methods.

Analysis of reporting time for identification of methicillin-resistant Staphylococcus aureus carriers using ChromID MRSA.

We assessed the reporting times for identification of nasal methicillin-resistant Staphylococcus aureus (MRSA) carriers in 2011 in a university-affiliated hospital using surveillance cultures incubated for 1 and 2 days with ChromID MRSA (bioMérieux, France). Of 2,732 nasal swabs tested, MRSA was detected in 829 (85.6%) and 140 (14.4%) swabs after 1 and 2 days of incubation, respectively, and the median reporting times for positive specimens were 33.7 hr (range, 18.2-156.9 hr) and 108.1 hr (range, 69.8-181.0 hr), respectively. Detection rate after 1-day incubation was 85%. Additional 1-day incubation improved detection rate; however, it prolonged the reporting times of positive specimens approximately up to 4 days because of the need for confirmatory tests such as species identification and susceptibility tests. Following a 2-day culture with ChromID MRSA, rapid confirmatory tests are warranted to reduce delay in identifying MRSA carriers.

Evaluation of a new real-time reverse transcription polymerase chain reaction assay for detection of norovirus in fecal specimens.

A new real-time reverse transcription polymerase chain reaction (RT-PCR) assay, the AccuPower Norovirus Real-time RT-PCR Kit, was evaluated in detection of human norovirus in stool specimens. Studies for detection limit, dynamic range, reproducibility, and cross-reactivity were performed. A total of 281 fecal specimens were tested using the AccuPower Norovirus Real-time RT-PCR Kit, and the results were compared with those obtained using another real-time RT-PCR system. Norovirus positivity and genotype were confirmed by direct sequencing. The lowest mean numbers of genome copies of GI and GII that could be detected by the assay were 12.3 and 5.6 RNA copies/reaction, respectively. The positive, negative, and overall percent agreements between the 2 real-time PCR assays were 99.0% (96/97), 95.1% (175/184), and 96.4% (271/281), respectively. The AccuPower Norovirus Real-time RT-PCR system showed good analytical and clinical performance and may be a useful diagnostic tool for norovirus infection.

Emergence of GII.4 Sydney norovirus in South Korea during the winter of 2012-2013.

Norovirus is the major cause of acute gastroenteritis worldwide. Between November 2012 and June 2013, 1718 stool samples were requested for norovirus antigen testing in the metropolitan areas of South Korea, and 91 samples were genotyped. The norovirus antigen-positive rate peaked at 52.8% in December 2012. [corrected]. A novel norovirus GII.4 variant, GII.4 Sydney 2012, was the most frequently found genotype (60.4%) during this period. This study demonstrates that norovirus activity increased during the winter of 2012-2013 in South Korea and that norovirus GII.4 Sydney 2012 was the cause of the norovirus epidemic during this period.

Evaluation of the SD Bioline Norovirus rapid immunochromatography test using fecal specimens from Korean gastroenteritis patients.

The analytical and clinical performance of a new rapid immunochromatography test, the SD Bioline Norovirus test, was evaluated for the detection of human norovirus in fecal specimens. The analytical performance studies were performed for detection limit, reproducibility, cross-reactivity, and interference. For comparison, 92 norovirus-positive stool samples and 126 norovirus-negative samples for which the results were confirmed by 2 different real-time PCR kits were used. The rapid immunochromatography test detected the equivalent of 4.48×10(6) copies/mL of the norovirus genome in stool samples. On performing the repeatability/reproducibility test, samples above this concentration all provided positive results (100%) and 97.8% of the samples slightly below this concentration (2.45×10(6) copies/mL) provided negative results. No cross-reactivity or interference was detected. Positive percent agreement (sensitivity), negative percent agreement (specificity), and overall percent agreement of the rapid immunochromatography test compared with testing by real-time PCR were 90.2%, 100%, and 95.9%, respectively. In addition, the rapid immunochromatography test was completed within 20 min. The SD Bioline Norovirus test was, therefore, easier and more rapid to perform and showed excellent reproducibility, no cross-reactivity, no interference, and high agreement compared with real-time PCR. Thus, this test is useful for rapid screening to identity norovirus infection.

Analysis of reagent lot-to-lot comparability tests in five immunoassay items.

We investigated the degree of lot-to-lot reagent variation for 5 common immunoassay items. We measured the commercial as well as in-house controls for α-fetoprotein (AFP), ferritin, CA19-9, quantitative hepatitis B surface antigen (HBsAg), and hepatitis B surface antibody (anti-HBs) 10 times each by using both the old and the new lot of reagents whenever a reagent lot was changed, over a period of 10 months. The differences in the mean control values, the percent difference (% difference), and the difference to between-run standard deviation ratio (D:SD ratio) between successive lots were calculated. The % difference in mean control values between 2 reagent lots ranged from 0.1 to 17.5% for AFP, 1.0 to 18.6% for ferritin, 0.6 to 14.3% for CA19-9, 0.6 to 16.2% for HBsAg, and 0.1 to 17.7% for anti-HBs except negative controls of HBsAg and anti-HBs. The maximum D:SD ratios between 2 lots were 4.37 for AFP, 4.39 for ferritin, 2.43 for CA19-9, 1.64 for HBsAg, and 4.16 for anti-HBs. Thus, we have experienced extensive variability in lot-to-lot reagent variation for 5 immunoassay items, indicating that reagent lot-to-lot comparability tests should be continuously performed and that laboratories should determine their own acceptance criteria for each item.

Contamination of X-ray cassettes with methicillin-resistant Staphylococcus aureus and methicillin-resistant Staphylococcus haemolyticus in a radiology department.

BACKGROUND: We performed surveillance cultures of the surfaces of X-ray cassettes to assess contamination with methicillin-resistant Staphylococcus aureus (MRSA). METHODS: The surfaces of 37 X-ray cassettes stored in a radiology department were cultured using mannitol salt agar containing 6 µg/mL oxacillin. Suspected methicillin-resistant staphylococcal colonies were isolated and identified by biochemical testing. Pulsed-field gel electrophoresis (PFGE) analysis was performed to determine the clonal relationships of the contaminants. RESULTS: Six X-ray cassettes (16.2%) were contaminated with MRSA. During the isolation procedure, we also detected 19 X-ray cassettes (51.4%) contaminated with methicillin-resistant Staphylococcus haemolyticus (MRSH), identified as yellow colonies resembling MRSA on mannitol salt agar. PFGE analysis of the MRSA and MRSH isolates revealed that most isolates of each organism were identical or closely related to each other, suggesting a common source of contamination. CONCLUSIONS: X-ray cassettes, which are commonly in direct contact with patients, were contaminated with MRSA and MRSH. In hospital environments, contaminated X-ray cassettes may serve as fomites for methicillin-resistant staphylococci.

Procalcitonin levels within 48 hours after burn injury as a prognostic factor.

PURPOSE: This study was performed to evaluate the clinical significance of procalcitonin in burn patients and to investigate whether procalcitonin levels at admission can be a prognostic indicator for sepsis and mortality. MATERIALS AND METHODS: Between January 2009 and December 2010, procalcitonin levels in 175 patients were tested within the first 48 hours after burn injury. Serum procalcitonin was measured using an enzyme-linked fluorescence assay. Mortality rates and positive culture rates of blood, wound, and sputum were evaluated among the subgroups divided by burn size, procalcitonin levels, and clinical prognosis. RESULTS: Positive blood culture and mortality rates correlated significantly with procalcitonin concentrations within the first 48 hours after burn injury. The area under the ROC curve for procalcitonin related to mortality was 0.844. Survival analysis revealed that the mortality rate was significantly higher in patients with procalcitonin concentrations ≥ 2 ng/mL than in patients with procalcitonin concentrations < 2 ng/mL (P < 0.001). Multivariate analysis demonstrated that procalcitonin was an independent prognostic factor for burn patients (Hazard ratio = 3.16, P = 0.001). CONCLUSIONS: Procalcitonin concentrations determined within the first 48 hours after burn injury can be a useful prognostic indicator for sepsis and mortality in burn patients.

Time-kill synergy tests of tigecycline combined with imipenem, amikacin, and ciprofloxacin against clinical isolates of multidrug-resistant Klebsiella pneumoniae and Escherichia coli.

This study evaluated the activity of tigecycline combined with imipenem, amikacin, and ciprofloxacin against clinical isolates of multidrug-resistant Klebsiella pneumoniae and Escherichia coli co-producing extended-spectrum ß-lactamases and acquired AmpC ß-lactamases. Broth microdilution tests were performed for cefotaxime, ceftazidime, cefepime, imipenem, amikacin, ciprofloxacin, and tigecycline. Time-kill synergy studies were tested for tigecycline plus imipenem, tigecycline plus amikacin, and tigecycline plus ciprofloxacin. Imipenem (MIC(90) = 1 µg/ml for both K. pneumoniae and E. coli) and tigecycline (MIC(90) = 2 µg/ml for K. pneumoniae and 1 µg/ml for E. coli) were the most potent agents. Combination studies with tigecycline plus imipenem resulted in synergy against 18 K. pneumoniae and 3 E. coli isolates; tigecycline plus amikacin yielded synergy against 8 K. pneumoniae and 3 E. coli isolates; tigecycline plus ciprofloxacin yielded synergy against 7 K. pneumoniae and 2 E. coli isolates. No antagonism was observed with any combination. In the present study, imipenem, amikacin, and ciprofloxacin led to indifferent and some synergistic effects in combination with tigecycline, and none of them demonstrated antagonistic effects.

[Epidemiological analysis of norovirus infection between March 2007 and February 2010].

BACKGROUND: Norovirus is a common cause of non-bacterial acute gastroenteritis worldwide, and norovirus infection shows symptoms such as vomiting and diarrhea in patients of all age groups. Mass outbreaks of norovirus infection have been recently reported in Korea. Herein, we investigated the epidemiological characteristics of acute norovirus gastroenteritis. METHODS: We analyzed 11,219 fecal specimens of patients with acute gastroenteritis symptoms from the 5 participating hospitals for 3 yr (March 2007-February 2010) to determine positive rates of detection using RIDASCREEN Norovirus ELISA (R-Biopharm AG, Germany) kit by year, prevalence season, sex, age, and region. RESULTS: Norovirus infection was prevalent during autumn and winter, and 13.0% specimens were positive for the infection. The positive rates of norovirus detection were 16.2%, 13.8%, and 9.9% in 2007, 2008, and 2009, respectively, and they tended to decrease every year. In 2007 and 2008, the epidemicity of norovirus started from October, reached its peak in November, and lasted until January. However, in 2009, it started from December, reached its peak in January, and lasted until February. Most patients were 0-3 yr old and this patient group had the highest positive rate. There was no significant inter-regional difference among the subjects. CONCLUSIONS: We performed epidemiological analysis of norovirus infection using ELISA assay. Reverse transcription-PCR indicated higher prevalence of norovirus infection as compared with that reported before 2007. Further studies are warranted to examine the changes observed in the epidemic period of 2009.

[Analysis of patients with positive acid-fast bacilli culture and negative T-SPOT.TB results].

BACKGROUND: T-SPOT.TB is a sensitive test that detects interferon-gamma producing T-cells in tuberculosis patients following stimulation with tuberculosis-specific antigens. Our study was aimed to investigate the possible causes of false negative results of the test by analyzing the patients with positive acid-fast bacilli (AFB) culture and negative T-SPOT.TB results. METHODS: We investigated 138 patients with positive AFB culture results reported between January 2009 and April 2010. Medical records of these patients were reviewed for the results of T-SPOT.TB test, AFB culture, PCR for Mycobacterium tuberculosis (TB-PCR), chest X-ray, drug treatment, etc. Diagnosis of tuberculosis was confirmed by positive TB-PCR or identification of Mycobacterium tuberculosis (MTB). Sensitivity of T-SPOT.TB test was calculated and the possible causes of AFB culture positive and T-SPOT.TB negative results were analyzed. RESULTS: T-SPOT.TB test was performed in 63 of the 138 patients with AFB culture positive results. Fifty-six (88.9%) were positive and 7 patients (11.1%) were negative on T-SPOT.TB test. Of these 7 negative cases, 4 were confirmed as nontuberculous mycobacteria (NTM), 2 were suspected as NTM and diagnosis could not be confirmed in 1. Six of these 7 patients were over 70 yr old and 6 patients had lymphocytopenia. T-SPOT.TB negative results were not observed in any of the 44 patients confirmed to have active tuberculosis (sensitivity 100%). CONCLUSIONS: Our results suggest that T-SPOT.TB test is very sensitive for diagnosing active tuberculosis. NTM may be the main cause of AFB culture positive and T-SPOT.TB negative results, but MTB infection in immunocompromised patients also has to be considered.

[Clinical usefulness of T-SPOT.TB test for the diagnosis of tuberculosis].

BACKGROUND: Tuberculosis-specific ELISPOT assay (T-SPOT.TB, Oxford Immunotec, UK) is a test that detects interferon-gamma producing T-cells after stimulating patient's lymphocytes with two kinds of tuberculosis-specific antigens (ESAT-6 and CFP-10). We evaluated clinical usefulness of T-SPOT.TB test in Korean adults with intermediate burden of tuberculosis and high rate of BCG vaccination at birth. METHODS: T-SPOT.TB test was performed in 79 patients and 64 healthy volunteers and these patients and volunteers were classified into four groups: group 1, patients with active tuberculosis (n=30); group 2, patients with not-active tuberculosis (n=27); group 3, patients without tuberculosis (n=24); group 4, healthy volunteers without tuberculosis history (n=62). Positive rates and average spot counts of T-SPOT.TB test were obtained among these groups. RESULTS: Positive rates of group 1 (96.4%) and group 2 (92.3%) were higher than those of group 3 (31.6%) and group 4 (27.4%) (P<0.0001). The sensitivity deduced from group 1 and specificity deduced from group 4 of T-SPOT.TB test were 96.4% and 72.6%, respectively. The average spot counts of group 1 and 2 were higher than those of group 3 and 4 (P<0.001). There was a tendency of increasing positive rate with increasing age. Overall agreement between T-SPOT.TB test and tuberculin skin test was 63.8% (kappa=0.29). CONCLUSIONS: T-SPOT.TB test would be a very useful screening and supplementary test for diagnosis of tuberculosis due to its high sensitivity. However, positive results of T-SPOT.TB should be cautiously interpreted because of high positivity in treated tuberculosis patients and healthy volunteers in Korea.

Cleft palate in a rare case of Variant Klinefelter syndrome with 48,XXXY/46,XY mosaicism.

Variant Klinefelter syndrome with 48,XXXY/46,XY mosaicism has been rarely reported, and its phenotypic features, compared with those of the classic type, have not been well delineated. We describe a newborn baby with phenotypic abnormalities, including cleft palate and low-set ears. The cytogenetic analysis of peripheral blood lymphocytes showed a karyotype of 48,XXXY[36]/46,XY[4]. To the best of our knowledge, this is the first case in which 48,XXXY/46,XY mosaicism was related to the congenital anomaly of cleft palate. This case underscores that cytogenetic analysis should be a mandatory workup for the patient with cleft palate and that cleft palate may be a rare clinical presentation of the variant Klinefelter syndrome.

Broth microdilution method to detect extended-spectrum beta-lactamases and AmpC beta-lactamases in enterobacteriaceae isolates by use of clavulanic acid and boronic acid as inhibitors.

This study was designed to evaluate the performance of the broth microdilution (BMD) method to detect production of extended-spectrum beta-lactamases (ESBLs) and AmpC beta-lactamases in Enterobacteriaceae by using clavulanic acid (CA) and boronic acid (BA) as ESBL and AmpC beta-lactamase inhibitors, respectively. A total of 100 clinical isolates of Enterobacteriaceae were analyzed. Mueller-Hinton broth containing serial twofold dilutions of cefotaxime (CTX), ceftazidime (CAZ), aztreonam (ATM), or cefepime (FEP) with or without either or both CA and BA was prepared. An eightfold or greater decrease in the MIC of CTX, CAZ, ATM, or FEP in the presence of CA and BA was considered a positive result for ESBL and plasmid-mediated AmpC beta-lactamase (PABL), respectively. In tests with CA, expanded-spectrum beta-lactams containing BA (CTX-BA, CAZ-BA, ATM-BA, and FEP-BA) showed higher positive rates in detecting ESBL producers than those without BA. The combination of CTX- and CAZ-based BMD tests with CA and BA showed sensitivity and specificity of 100% for the detection of ESBLs and PABLs. The BMD testing could be applicable for routine use in commercially available semiautomated systems for the detection of ESBLs and PABLs in Enterobacteriaceae.

[Comparison of diagnostic utility between procalcitonin and C-reactive protein for the patients with blood culture-positive sepsis].

BACKGROUND: Procalcitonin (PCT) is a relatively new marker for bacterial infections, and its diagnostic utility has been variable across the studies. We investigated the diagnostic utility of PCT for the patients with blood culture-positive sepsis, and compared it with that of C-reactive protein (CRP). METHODS: In 1,270 consecutive blood samples, PCT and CRP were simultaneously measured and results were compared according to the five categories of PCT concentrations (<0.05 ng/mL; 0.05-0.49 ng/mL; 0.5-1.99 ng/mL; 2-9.99 ng/mL; > or = 10 ng/mL). In 506 samples, they were further analyzed according to the result of blood culture. PCT and CRP were measured using enzyme-linked fluorescent assay (bioMerieux Co., France) and rate nephelometry (Beckman Coulter Co., USA), respectively. Their diagnostic utilities were compared using ROC curves. RESULTS: The mean concentrations of CRP in five categories of PCT were 15.4 mg/L, 42.1 mg/L, 101.2 mg/L, 125.0 mg/L, 167.1 mg/L, respectively (P<0.0001). Both PCT and CRP showed significant differences between the two positive and negative groups of blood culture (PCT, 8.47 vs 2.44 ng/mL, P=0.0133; CRP, 110.48 vs 59.78 mg/L, P<0.0001). The areas under the ROC curves (95% confidence interval) for PCT and CRP were 0.720 (0.644-0.788) and 0.558 (0.478-0.636), respectively, and showed a significant difference (P=0.005). CONCLUSIONS: The diagnostic utility of PCT is superior to that of CRP for the patients with blood culture-positive sepsis. PCT seems to be reliable for sepsis diagnosis, and may provide useful information for the critically ill patients.

[Molecular typing of Staphylococcus aureus isolated from blood on the basis of coagulase gene polymorphism and toxin genes].

BACKGROUND: Coagulase is produced by all strains of Staphylococcus aureus. The 3' coding region of the coagulase (coa) gene contains varying numbers of 81 bp tandem repeats. S. aureus produces a variety of extracellular protein toxins. Here, we typed S. aureus strains isolated from blood by coa gene restriction fragment length polymorphism (RFLP) patterns and toxin gene profiles. METHODS: A total of 120 strains of S. aureus were isolated from blood cultures during 2003-2006 at Kangdong Sacred Heart Hospital. The isolates were typed by PCR RFLP analysis of the coa gene and by multiplex PCR for detection of genes encoding enterotoxins (sea, seb, sec, sed, and see), toxic shock syndrome toxin-1 (tst), exfoliative toxins (eta and etb), mecA and femA. RESULTS: All the S. aureus strains were classified into 16 types on the basis of coa gene RFLP and could be further differentiated into 34 types according to the combined patterns of coa gene RFLP and toxin gene profiles. Of 85 methicillin-resistant S. aureus (MRSA) strains, 43 (50.6%) and 36 (42.4%) belonged to the RFLP pattern L5 and pattern L1, respectively. MRSA strains belonging to pattern L5 frequently carried tst (93.0%) or sec gene (81.4%), and strains belonging to pattern L1 frequently carried sea (88.9%) or see gene (44.4%). The rate of the pattern L5 in MRSA strains increased over the past few years and was higher in intensive care unit than in other wards. CONCLUSIONS: We typed S. aureus strains isolated from blood on the basis of coa gene RFLP and toxin genes. The strains belonging to coa gene RFLP pattern L5 and L1 appeared to be the major types of MRSA isolasted from bacteremia and revealed specific toxin gene profiles according to the coa gene RFLP patterns.