Microbiological Characteristics according to Transudative and Exudative Effusion in Pleural Fluid Culture / 대한임상미생물학회지

A total of 1,132 pleural fluid culture results obtained from October 2012 to July 2014 were analyzed to elucidate the microbiological characteristics according to transudative and exudative pleural fluid. The pleural fluid cultures were performed using aerobic and anaerobic blood culture bottles. The blood and pleural fluid for total protein, lactate dehydrogenase, and glucose measurement were submitted to laboratory at the same time with pleural fluid cultures. The rates for culture positivity, anaerobes isolation, and polymicrobials between transudative and exudative pleural fluid were 5.2% vs. 10.4%, 14.8% vs. 7.8%, and 14.8% vs. 10.9%.

Scoring System for Detecting Spurious Hemolysis in Anticoagulated Blood Specimens

BACKGROUND: The identification of in vitro hemolysis (IVH) using a hematology analyzer is challenging because centrifugation of the specimens cannot be performed for cell counts. In the present study, we aimed to develop a scoring system to help identify the presence of hemolysis in anticoagulated blood specimens. METHODS: Thirty-seven potassium EDTA anticoagulated blood specimens were obtained, and each specimen was divided into 3 aliquots (A, B, and C). Aliquots B and C were mechanically hemolyzed by aspirating 2 and 5 times, respectively, using a 27-gauge needle and then tested; aliquot A was analyzed immediately without any hemolysis. After the cells were counted, aliquots B and C were centrifuged and the supernatants were tested for the hemolytic index and lactate dehydrogenase levels. RESULTS: The 4 hematologic parameters were selected and scored from 0 to 3 as follows: or =38.5 for mean cell hemoglobin concentration (MCHC, g/dL); or =0.04 for red blood cell ghosts (10(12)/L); or =1.31 for difference value (g/dL) of measured hemoglobin and calculated hemoglobin; and or =3.35 for difference value (g/dL) of MCHC and cell hemoglobin concentration mean. The hemolysis score was calculated by adding all the scores from the 4 parameters. At the cutoff hemolysis score of 3, the IVH of aliquots B and C were detected as 64.9% and 91.9%, respectively. CONCLUSIONS: The scoring system might provide effective screening for detecting spurious IVH.

Evaluation of Blood Culture System for Culture of Body Fluids / 임상검사와정도관리

BACKGROUND: Invasive and life-threatening infections such as meningitis, pericarditis, peritonitis, empyema, and septic arthritis are diagnosed via culture of relevant body fluids (BFs). The blood culture system (BCS) has been reported to be a useful alternative for BFs culture to enhance recovery of fastidious microorganisms and reduce detection time. The aim of this study was to evaluate the diagnostic performance of BCS as compared to conventional culture method (CCM) in terms of culture yield. METHODS: The samples collected between October 2011 and September 2012 were processed using CCM, while those collected between October 2012 and September 2013 were processed using BCS. The 2 processes were compared in terms of total number of requests, recovery rate, turnaround time (TAT), and detection time. RESULTS: The positive rate using CCM was 18.2% (575/3,151), where 845 isolates were recovered from 575 specimens. Using BCS, the positive rate was 28.3% (922/3,260), where 1,472 isolates were recovered from 922 specimens. While comparing the 2 methods on terms of yield of clinically significant isolates, a greater number of fungi (1.2%) and anaerobic bacteria (1.4%) were recovered using BCS as compared to using CCM. The difference in TAT for positive samples was 24 hours and 40 minutes, where BCS had a shorter TAT than CCM. The mean detection time of 951 positive samples by BCS was 19 hours and 56 minutes. Growth of clinically significant isolates was detected within 24 hours. CONCLUSIONS: BCS for culture of BFs showed an improvement in recovery rate, number of isolates, and TAT as compared to CCM. Thus, BCS is a suitable alternative for culture of BFs.

Factors Influencing the False Positive Signals of Continuous Monitoring Blood Culture System / 대한임상미생물학회지

BACKGROUND: The false positive signals of a continuous monitoring blood culture system (CMBCS) increase the reporting time and laboratory cost. This study aimed to determine the highly relevant variables that discriminate false positive signals from true positive signals in a CMBCS. METHODS: Among 184,363 blood culture sets (aerobic and anaerobic), the signal-positive samples according to a BACTEC FX system (Plus Aerobic/F, BDA; Plus Anaerobic/F, BDN) and BacT/Alert 3D system (Standard Aerobic, BSA; Standard Anaerobic, BSN) between April 2010 and November 2013 were classified into two groups: false positive or true positive signals. The data of 15 parameters between the two groups were then statistically compared. RESULTS: Among total blood cultures, the positive rates of CMBCS signals according to BDA, BDN, BSA, and BSN were 4.9%, 2.8%, 3.8%, and 3.2%, respectively. The false positive rates of CMBCS signals according to BDA, BDN, BSA, and BSN were 0.6%, 0.1%, 0.1%, and 0.1%, respectively. The blood volume, detection time, time interval between admission and test, C-reactive protein concentration, leukocyte count, delta neutrophil index, and mean peroxidase index showed statistically significant differences between the two groups. CONCLUSION: There were no variables with diagnostic sensitivity and specificity for discriminating the two groups. Therefore, analysis of bacterial growth curves produced by CMBCS is needed for early and effective detection of false positive signals.

Evaluation of PCR-Reverse Blot Hybridization Assay, REBA Sepsis-ID Test, for Simultaneous Identification of Bacterial Pathogens and mecA and van Genes from Blood Culture Bottles

BACKGROUND: The aim of this study was to evaluate a newly developed PCR-based reverse blot hybridization assay (PCR-REBA), REBA Sepsis-ID (M&D, Wonju, Korea), to rapidly detect the presence of bacteremia and antimicrobial resistance gene in blood culture samples. METHODS: One thousand four hundred consecutive blood culture samples from patients with a delta neutrophil index greater than 2.7% were selected from March to July in 2013. Three hundred positive and 1,100 negative for bacterial growth in blood culture bottles samples were tested by conventional and real-time PCR-REBA, respectively. RESULTS: The overall agreement between the conventional identification test and the REBA Sepsis-ID test was 95.3% (286/300). Agreement for gram-positive bacteria, gram-negative bacteria, fungi, and polymicrobials was 94.5% (190/201), 97.3% (71/73), 100% (14/14), and 91.7% (11/12), respectively. The detection rate of the mecA gene from methicillin-resistant Staphylococcus isolates was 97.8% (90/92). The vanA gene was detected in one blood culture sample from which vancomycin-resistant Enterococcus was isolated. When the cycle threshold for real-time PCR was defined as 30.0, 2.4% (26/1,100) of negative blood culture samples tested positive by real-time PCR. CONCLUSIONS: The REBA Sepsis-ID test is capable of simultaneously and quickly detecting both causative agents and antimicrobial resistance genes, such as mecA and van, in blood culture positive samples.

First Report of Nocardia farcinica Bursitis in a Patient with Diabetes Mellitus

No abstract available.

Macrolide Resistance of Mycoplasma pneumoniae and Its Detection Rate by Real-Time PCR in Primary and Tertiary Care Hospitals

BACKGROUND: This study aimed to evaluate the prevalence of Mycoplasma pneumoniae in primary and tertiary care hospitals and its macrolide resistance rate. METHODS: Nasopharyngeal swabs were collected from 195 pediatric patients in primary and tertiary care hospitals from October to November 2010. The AccuPower MP real-time PCR kit (Bioneer, Korea) was used for the detection of M. pneumoniae. Direct amplicon sequencing was performed to detect point mutations conferring resistance to macrolides in the 23S rRNA gene. RESULTS: Among the 195 specimens, 17 (8.7%) were M. pneumoniae positive, and 3 of the strains (17.6%) obtained from these 17 specimens displayed the A2063G mutation in 23S rRNA. Three macrolide-resistant M. pneumoniae isolates were isolated from patients hospitalized at the primary care hospital. The positive rates of M. pneumoniae for the primary and tertiary care hospitals were 12.1% (15/124) and 2.8% (2/71), respectively (P=0.033). CONCLUSIONS: The positive rate of M. pneumoniae in the primary care hospital was higher than that in the tertiary care hospital. Simultaneous detection of M. pneumoniae and macrolide-resistant mutation genes in the 23S rRNA by real-time PCR is needed for rapid diagnosis and therapy of M. pneumoniae infections.

Molecular Characteristics of blaOXA-23-Producing Acinetobacter baumannii Isolated from a University Hospital / 대한임상미생물학회지

BACKGROUND: Multi-drug resistant (MDR) Acinetobacter baumannii has emerged as a significant infectious agent in hospitals worldwide. The purpose of this study was to determine the molecular characterization of MDR A. baumannii clinical isolates. METHODS: Two hundred eighty-five strains of non-duplicated A. baumannii collected from March to November 2011 from a university hospital laboratory located in the Wonju area of the Gangwon province of Korea were analyzed for MDR genes. RESULTS: All of the 285 imipenem-resistant A. baumannii isolates were encoded by a blaOXA-23-like gene, and all isolates with the blaOXA-23-like gene had the upstream element ISAba1. The 16S rRNA methylase gene armA was detected in 153 (50.2%) clinical isolates, but rmtA, rmtB, rmtC, rmtD and npmA were not detected in any isolates in the present study. The gene encoding aac(6')-Ib was the most prevalent aminoglycoside-modifying enzyme. The sequencing data for the quinolone resistance-determining region of gyrA and parC revealed the presence of Ser (TCA) 83 to Leu (TTA) and Ser (TCG) 80 to Leu (TTG) substitutions. All but one of the 285 A. baumannii isolates showed similar band patterns on repetitive extragenic palindromic-PCR profiles. CONCLUSION: The molecular characteristics of the resistance genes of MDR A. baumannii isolates obtained from the Wonju area of Gangwon province were similar to those of other areas in Korea.

The Prevalence of Vaginal Microorganisms in Pregnant Women with Preterm Labor and Preterm Birth

BACKGROUND: To investigate the risk factors for vaginal infections and antimicrobial susceptibilities of vaginal microorganisms among women who experienced preterm birth (PTB), we compared the prevalence of vaginal microorganisms between women who experienced preterm labor (PTL) without preterm delivery and spontaneous PTB. METHODS: Vaginal swab specimens from 126 pregnant women who experienced PTL were tested for group B streptococcus (GBS), Mycoplasma hominis, Mycoplasma genitalium, Ureaplasma urealyticum, Chlamydia trachomatis, Trichomonas vaginalis, Neisseria gonorrhoeae, Treponema pallidum, herpes simplex virus (HSV) I and II, and bacterial vaginosis. A control group of 91 pregnant women was tested for GBS. Antimicrobial susceptibility tests were performed for GBS, M. hominis, and U. urealyticum. RESULTS: The overall detection rates for each microorganism were: U. urealyticum, 62.7%; M. hominis, 12.7%; GBS, 7.9%; C. trachomatis, 2.4%; and HSV type II, 0.8%. The colonization rate of GBS in control group was 17.6%. The prevalence of GBS, M. hominis, and U. urealyticum in PTL without preterm delivery and spontaneous PTB were 3.8% and 8.7% (relative risk [RR], 2.26), 3.8% and 17.3% (RR, 4.52), and 53.8% and 60.9% (RR, 1.13), respectively, showing no significant difference between the 2 groups. The detection rate of M. hominis by PCR was higher than that by culture method (11.1% vs. 4.0%, P=0.010). The detection rates of U. urealyticum by PCR and culture method were 16.7% and 57.1%, respectively. CONCLUSIONS: There was no significant difference in the prevalence of GBS, M. hominis, and U. urealyticum between the spontaneous PTB and PTL without preterm delivery groups.

Evaluation of the MicroScan MICroSTREP Plus Antimicrobial Panel for Testing beta-Hemolytic Streptococci and Viridans Group Streptococci / 대한진단검사의학회지

BACKGROUND: In order to determine the clinical usefulness of the MicroScan (Siemens Healthcare Diagnostics, USA) MICroSTREP plus antimicrobial panel (MICroSTREP) for testing antimicrobial susceptibility of beta-hemolytic streptococci (BHS) and viridans group streptococci (VGS), we compared the accuracy of MICroSTREP with that of the CLSI reference method. METHODS: Seventy-five BHS and 59 VGS isolates were tested for antimicrobial susceptibility to ampicillin, penicillin, cefotaxime, meropenem, erythromycin, clindamycin, levofloxacin, and vancomycin by using MICroSTREP and the CLSI agar dilution method. RESULTS: The overall essential agreement with regard to minimum inhibitory concentrations (MICs) (within +/-1 double dilution) between MICroSTREP and the CLSI reference method was 98.2%, and categorical agreement (CA) was 96.9%. For the BHS isolates, the CA for erythromycin was 96.0%, whereas that for cefotaxime, meropenem, levofloxacin, and vancomycin (for ampicillin, penicillin, and clindamycin; 98.7%) was 100%. For the VGS isolates, the CA for penicillin was 84.7% and that for erythromycin, clindamycin, and vancomycin (for meropenem, 86.5%; for ampicillin, 88.1%; and for cefotaxime and levofloxacin, 96.6%) was 100%. All categorical errors of penicillin and ampicillin in the VGS isolates were minor. CONCLUSIONS: The accuracy of MICroSTREP is comparable to that of the CLSI reference method, suggesting that this panel can be effective for testing antimicrobial susceptibility of BHS and VGS.

Comparison of ATB FUNGUS 2 and VITEK-2 Antifungal Susceptibility (AST-YS01) Tests for Candida Species Isolated from Blood Culture / 대한임상미생물학회지

BACKGROUND: The VITEK-2 yeast susceptibility test (AST-YS01; bioMerieux, Hazelwood, MO, USA) has recently been introduced as a fully automated, commercial antifungal susceptibility test system that determines MIC endpoints spectrophotometrically, thereby eliminating subjective errors. We compared the ATB FUNGUS 2 (bioMerieux) and VITEK-2 (AST-YS01) systems to the CLSI M27 method for susceptibility testing of Candida isolates. METHODS: We tested 59 Candida species that were isolated from blood cultures at Wonju Christian Hospital between September 2008 and August 2009. We compared MIC results for amphotericin B, flucytosine, fluconazole and voriconazole using the ATB FUNGUS 2 and VITEK-2 (AST-YS01) tests to those obtained by the CLSI M27 broth microdilution method. RESULTS: Within two-fold dilutions of MICs, the agreement of the ATB FUNGUS 2 and VITEK-2 (AST-YS01) tests with the CLSI method according to antifungal agents were: amphotericin B, 100% vs. 100% flucytosine, 100% vs. 100% fluconazole, 83.6% vs. 98.3% and voriconazole, 83.6% vs. 96.7%, respectively. The categorical discrepancies for fluconazole and voriconazole were 20.4% and 18.6% for ATB FUNGUS 2, and 6.8% and 0% for VITEK-2 (ASTYS01). There were no major errors for fluconazole and voriconazole in either ATB FUNGUS 2 or VITEK-2 (AST-YS01) tests. CONCLUSION: The VITEK-2 system (AST-YS01) appears to be rapid and highly correlative with the CLSI method, suggesting that it is effective for antifungal susceptibility testing for Candida species in clinical settings.

Use of Boronic Acid Disks for the Detection of Extended-spectrum beta-lactamase and AmpC beta-lactamase in Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca and Proteus mirabilis / 대한임상미생물학회지

BACKGROUND: Accurate detection of organisms producing extended-spectrum beta-lactamase (ESBL) and AmpC beta-lactamase is very important for treatment of patients. However, unlike the ESBL confirmatory test, there are no guidelines for detection of organisms producing AmpC beta-lactamase. We evaluated a detection method using boronic acid (BA) for ESBL and AmpC beta-lactamase. METHODS: Clinical isolates of Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, and Proteus mirabilis showing intermediate resistance or resistance to cefoxitin (FOX) or positive for ESBL were tested. A > or =5 mm increase in zone diameter of ceftazidime/clavulanic acid/BA (CAZ/CA/BA) and/or cefotaxime/clavulanic acid/BA (CTX/CA/BA) versus CAZ/BA and/or CTX /BA was considered positive for ESBL. Likewise, a > or =5 mm increase in zone diameter of FOX/BA and/or cefotetan/BA (CTT/BA) versus FOX and/or CTT alone was considered positive for AmpC beta-lactamase. RESULTS: Among 622 clinical isolates, ESBL positive rates by the CLSI ESBL confirmatory test or by the BA method were 18.1% or 18.4% for E. coli, 38.3% or 40.4% for K. pneumoniae, 8.7% or 8.7% for K. oxytoca, and 14.8% or 14.8% for P. mirabilis, respectively. AmpC beta-lactamase positive rates using the BA method were 3.7% for E. coli, 33.3% for K. pneumoniae, 0% for K. oxytoca, and 7.4% for P. mirabilis. The detection rates of coproducing ESBL and AmpC beta-lactamase were 2.4% in E. coli 27.1% in K. pneumoniae, and 3.7% in P. mirabilis. CONCLUSION: The ESBL confirmatory method using BA was found to enhance the detection of ESBLs, even when potentially masked by AmpC beta-lactamase.

A Case of Bacteremia Caused by Rothia dentocariosa / 대한임상미생물학회지

Rothia dentocariosa, a pleomorphic gram-positive branching bacillus, is a common inhabitant of the nose and throat. It is a well-known causative agent of dental plaques and periodontal diseases. Although generally regarded as having a low virulence to humans, R. dentocariosa has been recognized as causative agents of infective endocarditis and bacteremia with increasing frequency. Consequently, it can be a very serious pathogen when isolated from usually sterile sites such as blood or cerebrospinal fluid. We report a case of Rothia dentocariosa bacteremia without endocarditis in a 17-month-old male patient with fever, vomiting and diarrhea.

Isolation of Pasteurella dagmatis from Dog-bite Wounds / 대한임상미생물학회지

Pasteurella dagmatis is an oxidase and catalase positive, facultative anaerobic, gram-negative coccobacillus classified as a member of the family Pasteurellaceae. Pasteurella species are commonly colonizing the oropharynx of healthy domestic and wild animals including cats and dogs. These are usually pathogenic to domestic animals, but rarely to human beings. Pasteurella infection of human causes pneumonia, empyema, meningitis, peritonitis, bone and joint infection and septicemia. Recently, we experienced a case of dog-bite wounds from which Pasteurella dagmatis was isolated in a 39-year-old woman. To our knowledge, this is the first report of Pasteurella dagmatis isolated from dog-bite wounds in Korea.

A Case of Escherichia coli O157 and Campylobacter species Gastroenteritis / 대한임상미생물학회지

Verotoxin-producing Escherichia coli O157 is a primary cause of severe and bloody diarrhea. Campylobacter spp. are one of the commonly reported bacterial cause of gastrointestinal infections throughout the world. Only a few cases involving both E. coli O157 and Campylobacter species have been reported. The authors simultaneously isolated verotoxin-producing E. coli O157 and Campylobacter species from the stool of a 3 year-old male with bloody diarrhea, fever and abdominal pain.

Identification Results of Aerobic Gram-positive Bacteria Isolated from Blood Cultures Using BBL Crystal GP ID System / 대한임상미생물학회지

BACKGROUND: Although most of aerobic gram-positive bacilli have been considered to be contaminants, gram-positive bacilli should be identified to the species level if they are isolated from sterile body sites such as blood, and from adequately collected clinical specimens if they are the predominant organisms. However, identification of gram-positive bacilli are difficult due to the enormous diversity of these organisms and the small number of readily available commercial identification systems in clinical laboratories. Gram-positive bacilli and coccorods isolated from blood cultures were tested with BBL Crystal Gram-Positive (GP) Identification (ID) system in order to evaluate the system's usefulness of identifying these bacteria. METHODS: Thirty-seven stock strains of aerobic gram-positive bacteria isolated from blood cultures between October 1998 and November 1999 at Wonju Christian Hospital were simultaneously tested by BBL Crystal GP ID system and API system. Three kinds of API system (API Coryne, API 50 CHB, and API 20 Strep) were tested according to gram stain results. Gram-positive bacilli or gram-positive coccorods consecutively isolated from blood cultures from May to November in 2000 were identified by BBL Crystal GP ID system. RESULTS: Among the 37 stock strains of aerobic gram-positive bacteria, agreement rate of identification between Crystal GP ID system and API system were 88% to the genus level and 63% to the species level in Bacillus species, and 90% to the genus level in Corynebacterium species. The isolation rate of gram-positive bacteria from blood cultures from May to November in 2000 to the genus level were: Bacillus; 41.9%(18/43), Corynebacterium; 37.2%(16/43), and the other grampositive coccorods; 20.9%(9/43). CONCLUSIONS: Crystal GP ID system is a useful identification system which, when combined with basic microbiological tests, should lead to satisfactory identification results for gram-positive bacteria isolated from blood cultures.

Identificatiion,Antimicrobial Susceptibility an Epidemiology of Klebsiella species Isolated from Clinical Specimen / 대한임상미생물학회지

BACKGROUND: In recent years, the incidence of extended-spectrum beta-lactamase (ESBL) producing Klebsiella has been steadily increased, and the newer species K. planticola and K terrigena, formerly regarded as nonpathogen, have been reported with astonishing frequency from human infectious processes by some investigators. The aim of this study is to elucidate the isolation rate and antimicrobial susceptibility of recent clinical Klebsiella isolates. METHOD: For the clinical Klebsiella isolates during the period of June 1999 to May 2000, isolation frequency of Klebsiella species by specimen, departments, age, and sex were analyzed. And antimicrobial susceptibilities were also analyzed. RESULT: Isolation rate of Klebsiella in order of decreasing frequency were K. pneumoniae (74:7%), K. oxytoca (12.1%), K. ozaenae(1.7%), K. planticola(1.0%), K. terngena(0.9%), and K, ornithinolytica (0.7%), respectively. K. rhinoscleromatis was not isolated. Compared with outpatients, increase of resistance rates of inpatients's Klebsiella isolates were 10% in ciprofloxacin, 15% in cefoperazone/sulbactam, and the others were ranged from 24% to 31%. Isolation rate of ESBL producing K. pneumoniae by double disk (DD) synergy test was 41%, and detection rates by antimicrobial agents were as follows: cefotaxime (95%), aztreonam (58%), and ceftriaxone (37%). Antimicrobial susceptibility rate with the exception of ampicillin and imipenem decreased from the range of 81%-96% on admission day to 29-62% after one week on admission. CONCLUSION: The isolation rates of K. planticola and K. terrigena were less than 1%. The proportion of ESBL producing K. pneumoniae was 41 %. And the vast majority of multidrug resistant Klebsiella including ESBL producing strains are acquired by hospitalization.

Identificatiion,Antimicrobial Susceptibility an Epidemiology of Klebsiella species Isolated from Clinical Specimen / 대한임상미생물학회지

BACKGROUND: In recent years, the incidence of extended-spectrum beta-lactamase (ESBL) producing Klebsiella has been steadily increased, and the newer species K. planticola and K terrigena, formerly regarded as nonpathogen, have been reported with astonishing frequency from human infectious processes by some investigators. The aim of this study is to elucidate the isolation rate and antimicrobial susceptibility of recent clinical Klebsiella isolates. METHOD: For the clinical Klebsiella isolates during the period of June 1999 to May 2000, isolation frequency of Klebsiella species by specimen, departments, age, and sex were analyzed. And antimicrobial susceptibilities were also analyzed. RESULT: Isolation rate of Klebsiella in order of decreasing frequency were K. pneumoniae (74:7%), K. oxytoca (12.1%), K. ozaenae(1.7%), K. planticola(1.0%), K. terngena(0.9%), and K, ornithinolytica (0.7%), respectively. K. rhinoscleromatis was not isolated. Compared with outpatients, increase of resistance rates of inpatients's Klebsiella isolates were 10% in ciprofloxacin, 15% in cefoperazone/sulbactam, and the others were ranged from 24% to 31%. Isolation rate of ESBL producing K. pneumoniae by double disk (DD) synergy test was 41%, and detection rates by antimicrobial agents were as follows: cefotaxime (95%), aztreonam (58%), and ceftriaxone (37%). Antimicrobial susceptibility rate with the exception of ampicillin and imipenem decreased from the range of 81%-96% on admission day to 29-62% after one week on admission. CONCLUSION: The isolation rates of K. planticola and K. terrigena were less than 1%. The proportion of ESBL producing K. pneumoniae was 41 %. And the vast majority of multidrug resistant Klebsiella including ESBL producing strains are acquired by hospitalization.