Comparison of Nasopharyngeal Aspirates and Nasopharyngeal Flocked Swabs for Respiratory Virus Detection / 대한임상미생물학회지

BACKGROUND: Nasopharyngeal aspirate (NPA) is known as the best specimen for accurate diagnosis of viral respiratory infections in pediatric patients, but the procedure is very annoying. Recently introduced flocked swabs have been reported to be easy to obtain a good quality specimen and comfortable to patients. The purpose of this study was to compare the sensitivities between NPA and nasopharyngeal flocked swabs (NPFS) for detection of respiratory viruses in children. METHODS: For this study, 111 hospitalized children with acute respiratory tract infections were recruited. NPA and NPFS were performed in parallel from each patient. NPFS were always collected after NPA. Specimens were tested for six common respiratory viruses in triplicate using indirect immunofluorescence (IIF), viral cultures, and multiplex reverse transcription PCR (RT-PCR). RESULTS: The proportion of specimens inadequate for IIF was higher in NPA (23.4%) than NPFS (5.4%). According to the consensus positive, the positive rates of NPFS were higher than those of NPA when using IIF (45.7% and 30.6%, P=0.048) and culture (38.7% and 27.9%, P=0.004). However, the false-positive rates of NPFS were higher than those of NPA when using IIF (12.4% and 1.2%, P=0.004). The positive rates of NPFS and those of NPA were not different in multiplex RT-PCR (67.6% and 55.9%, P=0.055). CONCLUSION: The higher sensitivity of IIF for NPFS specimens and of culture for respiratory viruses and the similar sensitivities in multiplex PCR could make them an alternative to NPA samples, especially in physician clinics or emergency rooms.

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 (bioMerieux, 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.

Erratum: Comparison of the BACTEC Peds Plus Pediatric Blood Culture Bottle to the BacT/Alert PF Pediatric Blood Culture Bottle for Culturing Blood from Pediatric Patients / 대한임상미생물학회지

English abstract of the paper, there is an error in the following to correct it.

Evaluation of an Immunochromatographic Assay for the Detection of Rotavirus / 임상검사와정도관리

BACKGROUND: Rotaviruses are the primary cause of severe acute gastroenteritis in infants and young children worldwide. We evaluated the performance of the new GENEDIA Rotavirus Ag Rapid test (Greencross Medical Science, Korea) immunochromatographic assay (ICA) for detecting human rotavirus in stool specimens, in comparison with ELISA and PCR assays. METHODS: One hundred rotavirus-positive stool samples and 150 rotavirus-negative stool samples, confirmed by ELISA and PCR tests, were analysed using the GENEDIA Rotavirus Ag rapid test. The positive agreement (sensitivity), negative agreement (specificity), and total agreement rates of the ICA compared to ELISA and PCR were determined. To assess the analytical performance of the ICA, we tested its detection limit, reproducibility, and cross-reactivity. RESULTS: The positive, negative, and total agreement rates of the ICA were 99%, 100%, and 99.6%, respectively, when compared with the results confirmed by ELISA and PCR. The total turnaround time of the ICA was less than 20 minutes. The lower limit of detection of the ICA for rotavirus was 1.33x10(3) TCID50/mL, which was similar to that of ELISA but higher than that of PCR. No cross-reactivity was detected for 11 viruses and 19 bacteria. CONCLUSIONS: The GENEDIA Rotavirus Ag rapid test was easy to perform and provided rapid results, which showed high agreement with those obtained using ELISA and PCR. This test appears to be a useful tool for the diagnosis of rotavirus infection.

Comparison of Rapid Antigen Test and Real-Time Reverse Transcription PCR for the Detection of Influenza B Virus / 임상검사와정도관리

BACKGROUND: Rapid antigen test and real-time reverse transcription PCR (rRT-PCR) are widely used for the detection of influenza A virus. In this study, we evaluated and compared the effectiveness of a rapid antigen test, currently used for detecting influenza B virus, with the effectiveness of using rRT-PCR for the same purpose. METHODS: Samples obtained from 92 patients during an outbreak of influenza B were assessed using the rapid antigen test (SD BIOLINE Influenza Ag; SD, Korea) and rRT-PCR (Anyplex FluA/B Real-time Detection; Seegene, Korea). RESULTS: The sensitivity and specificity of the rapid antigen test were 69% and 100%, respectively, in detecting influenza B when compared to rRT-PCR. Twenty-nine patients (31.5%) were positive for both rapid antigen test and rRT-PCR, while 50 (54.3%) were negative for both rapid antigen test and rRT-PCR. The overall concordance rate between rapid antigen test and rRT-PCR was 85.9%. Thirteen patients (14.1%) were positive only for rRT-PCR. CONCLUSIONS: The rapid antigen test showed high specificity and good correlation with rRT-PCR and is likely to be as useful in the detection of influenza B viruses.

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 microg/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.

Juvenile Rheumatoid Arthritis in Children with Ebstein-barr Virus Infection

OBJECTIVE: Juvenile rheumatoid arthritis (JRA) may occur in the wake of infection with several viruses including Ebstein-barr virus (EBV). EBV remains an interesting target. To determine the possible role of EBV infections in the clinical course of JRA, we attempt to demonstrate the radiologic changes and the frequency prescription of etanercept rather than classic therapy. METHODS: Total of 87 patients with JRA, who were hospitalized in Hangang Sacred Hospital and Kangnam Sacred Hospital in Seoul from 2002 to 2010, were assessed serologically for EBV infection (anti EBV VCA IgM and IgG) at admission. Patients with JRA were devided 2 groups, one is EBV VCA IgG (+) JRA patients who had been infected before and another is EBV VCA IgG (-) JRA patients who had not. RESULTS: EBV VCA IgG (+) were seen in 55 patients (63.2%). 31 boys (76%) and 24 girls (52%) were infected with EBV. The mean age of patients of EBV (+) JRA was 8.2+/-3.6 years and that of EBV (-) JRA was 5.3+/-3.4 years. 7 of EBV (+) JRA (13%) developed radiologic change within 2 years, compare with none of EBV (-) JRA. 22 of EBV (+) JRA (49%) with JRA did not respond to the classic therapy, compare with 7 of EBV (-) JRA (22%). CONCLUSION: JRA patients with past EBV infection were older in ages, more in male, more radiologic changes, needed more biologic treatment than those without past EBV infection.

Removal of PCR Inhibitors in Real-time PCR for Mycobacterium tuberculosis / 대한임상미생물학회지

BACKGROUND: The inhibition rates for nucleic acid tests of Mycobacterium tuberculosis have been reported to range from less than 1% to more than 10%. Specimen dilution, boiling, addition of bovine serum albumin (BSA), and a silica membrane can be used to override amplification inhibitors in nucleic acid tests of M. tuberculosis. The inhibition rate for real-time PCR of M. tuberculosis (COBAS TaqMan MTB test; Roche Diagnostics, Manheim, Germany) and effective strategies to override PCR inhibitors were investigated in this study. METHODS: The inhibition rate for COBAS TaqMan MTB test was investigated in 980 clinical specimens. The effectiveness of PCR inhibitor removal by repeated run, dilution, boiling, addition of BSA, and use of silica membrane were evaluated in the inhibited specimens. RESULTS: Inhibitory substances were present in 4.1% of specimens (40/980). Among 40 inhibited specimens, inhibitory substances were removed in 12 (30%), 30 (75%), 27 (67.5%), 25 (62.5%) and 12 (30%) specimens with repeated run, dilution, addition of RBS, boiling and use of silica membrane, respectively. CONCLUSION: The overall inhibition rate for the COBAS TaqMan MTB test was 4.1%. Dilution, boiling and addition of BSA were shown to be more effective than repeated run and use of silica membrane for removal of PCR inhibitors. A combination of two methods might be useful and should be studied in the future.

Interpretation of Weak-Positive Bands in a Multiplex PCR Using Seeplex RV12 ACE Detection Kit / 임상검사와정도관리

BACKGROUND: Multiplex PCR assay is a sensitive tool for the detection of various respiratory viruses. Seeplex RV12 ACE Detection (Seegene, Korea) assay is a multiplex RT-PCR assay for detection of 12 respiratory viruses. We had observed several cases with faint bands in the test. Those results were investigated in this study. METHODS: A total of 163 specimens were tested with Seeplex RV12 ACE Detection assay. The amplicons showing faint band in electrophoresis were reamplified and sequenced. RESULTS: A total of 99 viruses were detected in 80 specimens (49.1%). Twenty-four amplicons showed faint band in eletrophoresis. All of influenza virus A, parainfluenza viruses (PIV), coronavirus OC43, human metapneumovirus (HMPV) and adenovirus amplicons were reamplified, but 4 of 12 human rhinovirus amplicons were not reamplified. Sequences of reamplified PCR products showed homology of 95-99% to those of corresponding viruses in the National Center for Biotechnology Information database. CONCLUSIONS: Faint bands of influenza virus A, PIV-1, PIV-3, coronavirus OC43, HMPV and adenovirus in Seeplex RV12 ACE Detection assay are specific bands and seems to be weak positive results.

Comparison of Clinical and Laboratory Standards Institute and European Committee on Antimicrobial Susceptibility Testing Breakpoints for beta-Lactams in Enterobacteriaceae Producing Extended-Spectrum beta-Lactamases and/or Plasmid-Mediated AmpC beta-Lacta / 대한임상미생물학회지

BACKGROUND: In 2010, the Clinical and Laboratory Standards Institute (CLSI) revised breakpoints for cephalosporins and carbapenems and indicated that extended-spectrum beta-lactamase (ESBL) testing is no longer necessary for Enterobacteriaceae. We compared the results of the CLSI 2010 and the European Committee on Antimicrobial Susceptibility Testing (EUCAST) MIC breakpoints for Enterobacteriaceae producing ESBL and/or plasmid-mediated AmpC beta-lactamase (PABL). METHODS: A total of 94 well-characterized clinical isolates of Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Salmonella spp., Shigella spp., Citrobacter freundii, Enterobacter aerogenes, Enterobacter cloacae, and Serratia marcescens were analyzed. Of them, 57 were ESBL producers, 24 were PABL producers, and 13 were ESBL plus PABL co-producers. Broth microdilution MIC tests were performed for cefotaxime, ceftazidime, aztreonam, cefepime, and imipenem. RESULTS: Among the 94 isolates containing ESBL and/or PABL, the number of isolates that were susceptible to cefotaxime, ceftazidime, aztreonam, cefepime, and imipenem according to the CLSI 2010 vs. the EUCAST breakpoints were 4 (4.3%) vs. 4 (4.3%); 26 (27.7%) vs. 8 (8.5%); 37 (39.4%) vs. 14 (14.9%); 71 (75.5%) vs. 31 (33.0%); and 76 (80.9%) vs. 90 (95.7%), respectively. Of the 18 isolates that were not susceptible to imipenem according to the CLSI 2010 breakpoints, 13 isolates (72.2%) were P. mirabilis. CONCLUSION: The CLSI 2010 MIC breakpoints without tests to detect ESBL and/or PABL for Enterobacteriaceae could be unreliable. Thus, special tests for ESBLs and AmpC beta-lactamases are required to detect the resistance mechanisms involved.

Evaluation of Rapid Antigen Test for the Detection of Norovirus Infection: Comparison with ELISA and Real Time Quantitative Reverse Transcription PCR Assays

BACKGROUND: Norovirus is a leading cause of epidemic and sporadic acute gastroenteritis worldwide. Because of the rapid transmission of the virus, early detection is important to prevent outbreak of norovirus infection. To evaluate the performance of a newly introduced rapid antigen test for detecting human norovirus in stool specimens, we compared it with the established ELISA test and real time quantitative reverse transcription PCR (qRT-PCR). METHODS: One hundred and eighty-four stool samples were analyzed by rapid antigen test (Denka-Seiken, Japan), ELISA (R-Biopharm, Germany), and qRT-PCR (R-Biopharm, Germany). Overall percent agreement, percent positive agreement (PPA), and percent negative agreement (NPA) of the rapid antigen test in comparison with ELISA and qRT-PCR were obtained. RESULTS: Positive rates of rapid antigen test, ELISA, and qRT-PCR were 44.0% (81/184), 51.6% (95/184), and 42.9% (79/184), respectively. Seventy samples (38.0%) showed all positive, and 86 samples (46.7%) showed all negative results by three methods. Overall percent agreement of three methods was 84.8% (156/184). Overall percent agreement, PPA, and NPA of the rapid antigen test in comparison with qRT-PCR were 89.1%, 88.6%, and 89.5%, respectively, and those of the rapid antigen test in comparison with ELISA were 90.2%, 83.2%, and 97.8%, respectively. Total procedure of the rapid antigen test was finished within 20 min. CONCLUSIONS: Rapid antigen test was easier and quicker to perform, and showed high agreement rates with ELISA and qRT-PCR. This test may be useful for rapid screening of norovirus infection.

Comparison of the BACTEC Peds Plus Pediatric Blood Culture Bottle to the BacT/Alert PF Pediatric Blood Culture Bottle for Culturing Blood from Pediatric Patients / 대한임상미생물학회지

BACKGROUND: We compared the BACTEC Peds Plus (Becton Dickinson, USA) and BacT/Alert PF (bioMerieux, France) pediatric blood culture bottles in the context of recovery and time to detection (TTD) of bacteria and fungi from pediatric patients. METHODS: Blood samples were collected for culture from pediatric patients who were hospitalized during 2010 at a university hospital. BACTEC Peds Plus and BacT/Alert PF bottles were placed in the BACTEC FX and BacT/Alert 3D blood culture system, respectively, and tested for 5 days. Bottles flagged by instruments as positive were removed from the instruments and the TTDs were recorded. RESULTS: A total of 5,018 sets (1 set, 1 BACTEC Peds Plus and 1 BacT/Alert PF) were evaluated. Overall, the recovery proportions for BACTEC Peds Plus and BacT/Alert PF bottles were 57% (134/195) and 69% (112/195), respectively. There was a significant difference between the 0.38% contamination rate in BacT/Alert PF bottles and the 0.16% contamination rate in BACTEC Peds Plus bottles (P=0.035). The average TTD for all microorganisms was significantly decreased for the BACTEC Peds Plus bottles (P=0.021), but was increased for Candida parapsilosis compared to the results for the BacT/Alert PF bottles (P=0.028). CONCLUSION: We conclude that the rate of detection and contamination is higher when BacT/Alert PF bottles are used than when BACTEC Peds Plus bottles are used for pediatric blood culture. The BACTEC Peds Plus bottles detect nearly all enrolled microorganisms significantly faster than do the BacT/Alert PF bottles.

A Serial Study of Hematologic Change in Burned Patients / 임상검사와정도관리

BACKGROUND: Hematologic changes in burned patients show unique patterns with time after burn injury. In this study, we analyzed the changes of leukocyte count, hemoglobin concentration, and platelet count according to elapsed time and burn size. METHODS: A total of 265 burned patients were included in this retrospective study. The changes in leukocyte count, hemoglobin, and platelet count according to elapsed time were analyzed every 6 hours from immediately after burn injury until day 2, and then every 24 hours from day 3 to day 14. The differences according to burn size were also analyzed. All the results were expressed as mean+/-standard deviation. RESULTS: Leukocyte count, hemoglobin, and platelet count began to increasing immediately after burn injury, reaching the peak within 12 hours after injury, and then decreased. WBC count was lowest at days 3 to 4 and then began increasing, reaching the second peak at day 7-8. Hemoglobin level continuously decreased and remained at the level of anemia from day 4 to day 14. Platelet count was lowest at days 3-4 and then continuously increased until day 14. The wider the burn sizes were, the greater the changes in leukocyte count, hemoglobin, and platelet count, with 11-40% of the patients showing the most remarkable increase in the number of platelets after day 4. CONCLUSIONS: The leukocyte count, hemoglobin concentration and platelet count were dramatically changed within the first 72 hours after burn injury and the wider the burn sizes were, the greater these changes were. These results could be used as reference data for interpreting the results of complete blood count in burned patients.

Use of Immunochromatographic Assays for Identification of Mycobacterium tuberculosis Complex from Broth Cultures / 임상검사와정도관리

BACKGROUND: Broth cultures are increasingly used to detect acid-fast bacilli (AFB). Rapid, simple and accurate methods for differentiation of Mycobacterium tuberculosis complex (MTBC) and nontuberculosis mycobacteria from broth cultures are needed. Immunochromatographic assays (ICTs) for identification of MTBC have been developed. METHODS: The abilities of the BD MGIT TBc Identification Test (Becton Dickinson, USA) and the SD Bioline TB Ag MPT64 (Standard Diagnostics, Korea) to detect MTBC were evaluated in 44 AFB-positive broth cultures. The results of 2 ICTs were compared to those of real-time PCR. RESULTS: The BD MGIT TBc Identification Test and the SD Bioline TB Ag MPT64 showed concordant results with real-time PCR by 100% and 97.7%, respectively. The sensitivity of the BD MGIT TBc Identification and the SD Bioline TB Ag MPT64 was 100% for both, and the specificities of those were 100% and 95.2%, respectively. CONCLUSIONS: Both ICTs are rapid methods for identification of MTBC from broth cultures, and the results of ICTs are in accord with those of real-time PCR.

Clinical Availability of Serum Procalcitonin in Children with Bacterical Infection / 소아감염

PURPOSE: The aim of this study was to identify clinical availability of serum procalcitonin (PCT) compared with C-reactive protein (CRP) in prediction of bacterial infection in children. METHODS: A retrospective study was conducted with children who had been admitted to the Department of Pediatrics with bacterial and viral infection between April 2008 and March 2009 and children who were admitted with Juvenile rheumatoid arthritis (JRA) between August 2007 and July 2009. Serum PCT levels were measured using an enzyme-linked fluorescent assay. RESULTS: The study population included 10 patients with bacterial infection (group I), 69 with viral infection (group II), and 35 with JRA (group III). Mean PCT levels were significantly higher in group I than in group II or group III (P0.05). Using a cutoff of 0.5 ng/mL for PCT and 8 mg/L for CRP, sensitivity and specificity in distinguishing between group I and the other groups were 60.0% and 92.3% for PCT and 60.0% and 40.1% for CRP, respectively. Positive and negative predictive values were 42.9% and 96.0% for PCT and 10.0% and 92.6% for CRP, respectively. CONCLUSION: Measurement of PCT concentrations appears to be more useful than CRP for distinguishing between bacterial infection and non-bacterial diseases in children.

Comparison of Rapid Antigen Test and Real-Time Reverse Transcriptase PCR for Diagnosing Novel Swine Influenza A (H1N1) / 대한임상미생물학회지

BACKGROUND: Novel swine influenza (H1N1) was first identified in Mexico in April 2009. Because of its high infectivity and worldwide distribution, a rapid and efficient screening test is necessary. Here we evaluated the usefulness of a rapid antigen test currently in use, compared to real-time RT-PCR (rRT-PCR) as a screening test for detection of novel swine influenza (H1N1). METHODS: A total of 1,228 patients who visited Hallym University Kangdong Sacred Heart Hospital with influenza-like illness between 14 August 2009 and 30 September 2009, and were tested by both rapid antigen and rRT-PCR tests, were enrolled in this study. RESULTS: Sensitivity, specificity, predictive value of a positive test, and predictive value of a negative test for the rapid antigen test were 30.5%, 99.2%, 86.4% and 90.1%, respectively. Fifty-one (4.2%) patients were positive for both rapid antigen test and rRT-PCR, and 1,053 (85.7%) were negative for both rapid antigen test and rRT-PCR. A total of 124 (10.1%) patients showed a discrepancy between the two tests. Among them, 116 (9.4%) were only positive for rRT-PCR and 8 (0.7%) were only positive for the rapid antigen test. The latter 8 patients all showed negative H1/M2 results in rRT-PCR. There were significant differences in detection rates of the rapid antigen test between different H1 Ct (threshold cycle) interval groups and for different age groups (P<0.05). CONCLUSION: Although the rapid antigen test is easy to perform and provides fast results, its limits as a screening test for detection of novel swine influenza (H1N1) due to its low sensitivity compared to rRT-PCR need to be considered in practical situations.

Clinical Usefulness of T-SPOT.TB Test for the Diagnosis of Tuberculosis / 대한진단검사의학회지

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.

Isolation of Healthcare-Associated Pathogens from Cellular Phones Used by Medical Personnel / 병원감염관리

BACKGROUND: Cellular phone has become a necessary device for communicating in hospitals. Cellular phones contaminated with bacteria may serve as a fomite in the transmission of pathogens by the hands of medical personnel. We investigated the bacterial contamination of cellular phones used by medical personnel in a tertiary hospital. METHODS: Culture swabs were obtained from 101 cellular phones and 99 anterior nasal cavities from medical personnel using cellular phones. The swabs were inoculated on blood agar, MacConkey agar, mannitol salt agar, and enterococcal broths containing 6microgram/mL vancomycin for 48 h at 37degrees C. The bacteria were identified on the basis of colony morphology, gram staining characteristics, catalase test, coagulase test, and DNase test; Microscan (Siemens, USA) was used for the identification of enterococci. RESULTS: Of the 101 cellular phones, 13 were contaminated with Staphylococcus aureus (including 4 methicillin-resistant S. aureus [MRSA]), 61 with coagulase-negative staphylococci (CoNS) (including 38 methicillin-resistant CoNS), 27 with Micrococcus spp., 11 with diphtheroids, 67 with Bacillus spp., and 4 with viridans streptococci. No gram-negative bacilli were isolated. Nasal swabs yielded 36 S. aureus, including 9 MRSA. Only 1 of 9 cellular phones used by the MRSA carriers was contaminated with MRSA. CONCLUSION: Cellular phones used by some medical personnel were contaminated with pathogens such as S. aureus or MRSA. Although, the clinical implications of pathogens isolated from cellular phones have not been fully investigated, pathogens could be transmitted by the hands of medical personnel who are cellular phone users.

Analysis of Patients with Positive Acid-fast Bacilli Culture and Negative T-SPOT.TB Results / 대한진단검사의학회지

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.