Comparison of Red Blood Cell Hemolysis Using Plasma and Serum Separation Tubes for Outpatient Specimens

BACKGROUND: To rapidly obtain outpatient results, we use plasma separation tubes (PST) for chemistry analysis. If lactate dehydrogenase measurement is required, serum separation tubes (SST) are used. There has been no evaluation of hemolysis with these tubes. We compared the hemolytic index (HI) obtained by using PST and SST and applied this for choosing appropriate tubes for clinical laboratories. METHODS: The HI of specimens obtained from outpatients visiting Asan Medical Center between July and December 2012 was analyzed. The HI was scored from 0 to 10 by using the Toshiba 200FR (Toshiba Medical Systems Co., Japan). HI was classified by sample tube type, and significant hemolysis was defined as a HI of 2 or more. For significant hemolysis cases, medical records were reviewed to identify the causes. RESULTS: Among 171,519 specimens, significant hemolysis was observed in 0.66% of specimens (0.68% of PST specimens, 0.46% of SST specimens). The mean HI in PST was 0.18 (SD: 0.43) and that in SST was 0.14 (SD: 0.37). The proportion of significant hemolysis was significantly higher in PST than in SST (P=0.001). The cause of significant hemolysis was identified as chemotherapy and prosthetic valve in 48.1% of specimens. Complex sampling errors may have caused significant hemolysis in the remaining 51.9% of specimens. CONCLUSIONS: The incidence of hemolysis was slightly higher for PST than SST, although both were <1%. PST are thought to be more useful than SST in outpatient testing because of rapid turnaround time, greater sample volume, and less risk of random errors due to fibrin strands.

A Comparative Study to Determine the Most Suitable Fixative for Immunocytochemical Staining of Cytospin Slides / 임상검사와정도관리

BACKGROUND: Fixation of cells is a critical procedure that can determine the success of immunocytochemical staining (ICC) of cytospin slides. In this study, we evaluated the efficacy of a number of fixatives to determine the ideal fixative for ICC of cytospin slides. METHODS: Sixteen patients with metastatic neoplasm in the body cavity were enrolled. Cytospin slides were prepared from each patient using 5 different fixatives (cold acetone, 95% ethanol, 1:1 methanol:ethanol, 3.7% formalin, and 3:1 methanol:acetone), and the suitability of each for use with Wright's stain was compared. For 4 of the samples, appropriate ICCs were performed using all 5 fixatives and the results were compared, while for 11 samples, only the first 3 fixatives were used for ICC. RESULTS: Using Wright stain, cold acetone, 95% ethanol, and 1:1 methanol:ethanol fixatives all showed similar efficacy when compared to the conventional methanol fixation method. However, the stain quality using 3.7% formalin or 3:1 methanol:acetone fixatives was poor due to deterioration of cell adhesion and distortion of cell morphology. Using ICC, cold acetone fixative showed stronger and more tumor-specific stainability than the 95% ethanol (decreased stainability in 6 stained slides, false positive staining of histiocytes/neutrophils in 4 stained slides, no staining of CD3 and terminal deoxynucleotidyl transferase [TdT]) and 1:1 methanol:ethanol fixatives (decreased stainability in 3 stained slides, false positive staining of histiocytes/neutrophils in 2 stained slides, no staining of CD3 and TdT). CONCLUSIONS: Cold acetone fixative was the most efficacious among the 5 fixatives tested in this study; therefore, it is the most appropriate fixative in the preparation of cytospin slides for ICC.

Occurrence of a PCR-Positive but Culture-Negative Case for vanB Vancomycin-Resistant Enterococci in Stool Surveillance

We present here occurence of PCR-positive but culture-negative for vanB vancomycin-resistant enterococci (VRE) from an enrichment broth of a stool surveillance culture in a patient suffering from Parkinson's disease, who was transferred from a long-term care facility because of aspiration pneumonia. He developed VRE bacteriuria at the hospital day 42. vanA and vanB genes were detected from 6 microg/mL vancomycin-containing BBL Enterococcosel broth (BD), of which color changed to black after overnight incubation, by both Seeplex VRE detection (Seegene, Seoul, Korea) and Anyplex VanR real-time PCR (Seegene). Subculture of an aliquot of the blackened broth on blood agar plate produced only vanA VRE. All of the four subsequent consecutive surveillance cultures for 1 month until discharge at hospital day 75 resulted in PCR-positive but culture-negative for vanB VRE from the enrichment broths. Therefore, the presence of a non-enterococcal intrinsic reservoir bearing vanB is more likely than low burden of vanB VRE. Considering the rare occurrence of vanB VRE in Korea, vanB-positive PCR results from the enrichment broth requires confirmation by microbiological studies.

Pitfalls of the Clinical and Laboratory Standards Institute's Revised Breakpoints on Interpretation of the Cephalosporin Susceptibility of an Extended-Spectrum beta-lactamase Producing Klebsiella pneumoniae: Analysis of a 2010 Nationwide Proficiency Surve / 임상검사와정도관리

BACKGROUND: In 2010, the Clinical and Laboratory Standards Institute (CLSI) revised the minimum inhibitory concentration (MIC) breakpoints of cephalosporins and aztreonam to exempt extended-spectrum beta-lactamase (ESBL) confirmatory tests for Enterobacteriaceae. However, the CLSI did not change the MIC breakpoint of cefepime. Here, a proficiency survey of a strain of ESBL-producing Klebsiella pneumoniae was analyzed for MIC distribution and interpretation of cephalosporins and aztreonam. METHODS: The survey strain, K. pneumoniae, which produced SHV-18, was distributed to 170 clinical laboratories as 1 of 5 presumptive clinical specimens through the proficiency survey of the clinical microbiology division of the Korean Association of Quality Assurance for Clinical Laboratories (KAQACL). MIC, zone diameter of inhibition (ZDI), and interpretation of tested antimicrobials, methods of antimicrobial susceptibility testing (AST), and ESBL confirmatory results were collected. RESULTS: According to the revised breakpoints of the 2010 CLSI guidelines, MIC results indicated resistance to aztreonam in 100%, cefepime in 5.5%, cefotaxime in 20%, ceftazidime in 100%, and ceftriaxone in 100% of samples by broth microdilution methods. ZDI results also indicated resistance to aztreonam in 75%, cefepime in 0%, cefotaxime in 66.7%, ceftazidime in 100%, and ceftriaxone in 80% of samples by disk diffusion method. Ninety (75.6%) participants performed an ESBL confirmatory test, and 89 (98.9%) reported ESBL-positive tests. Of the 55 laboratories that tested the susceptibility of cefepime, 50 (90.9%) self-reported to be "resistant" because of ESBL-positive results. CONCLUSIONS: In conclusion, susceptibility testing of ESBL producers against certain cephalosporins is not reliable enough to apply the revised breakpoints presented in the 2010 CLSI guidelines. It is therefore necessary to reach a consensus for interpretation of ASTs of ESBL producers in Korea. Ideally, clinicians should be provided two interpretations based on both the revised breakpoints and ESBL confirmatory testing.

A Case of Bacteremia by Neisseria gonorrhoeae Coincident with Massive Hemorrhage of Esophageal Varices / 대한진단검사의학회지

A 42-yr-old man with hepatitis B virus associated liver cirrhosis was admitted to the emergency room because of multiple seizures, a history of chills and myalgia over the previous 2 weeks, and 3 days of melena. He was febrile with a temperature of 38.0degrees C. There were no symptoms and signs related to the genitourinary system, skin, or joints. Three sets of blood cultures were obtained and oxidase-positive, gram-negative diplococci were detected after 25.9-26.9 hr of incubation in all aerobic vials. The organism was positive for catalase and oxidase, and was identified as Neisseria gonorrhoeae, using a Vitek Neisseria-Haemophilus Identification card (bioMerieux Vitek, Inc., USA). Further, 16S rRNA sequencing of this isolate revealed a 99.9% homology with the published sequence of N. gonorrhoeae strain NCTC 83785 (GenBank Accession No. NR_026079.1). Acute bleeding by variceal rupture seems to be a likely route of introduction of N. gonorrhoeae from the mucosa into the blood. To the best of our knowledge, this is the first case of gonococcal bacteremia in Korea.

Cryoglobulinemic vasculitis and monoclonal gammopathy in end-stage renal disease

No abstract available.