Soo Jin Yoo

Inferior prognostic outcome in acute promyelocytic leukemia with alterations of FLT3 gene

Alterations of the FLT3 gene, in the form of internal tandem duplications (ITD) and D835 point mutations, occur frequently in acute promyelocytic leukemia (APL). We therefore evaluated the frequency and clinical relevance of FLT3 aberrations in a series of Korean APL patients. We assayed FLT3 ITD and D835 mutation status in 75 newly diagnosed APL patients and we correlated the presence of these mutations with clinical parameters and outcomes. Of the 75 patients, fifteen (20.0%) carried FLT3 mutations, nine (12.0%) with FLT3 ITD, seven (9.3%) with D835 mutations and one with both types. Patients presenting with higher leukocyte counts (>10×109/L) had a significantly higher frequency of FLT3 ITD (P = 0.030). There was no association between FLT3 aberrations and other clinicohematologic features including age, gender, M3 variant morphology and PML/RARα subtype. Death at presentation before induction chemotherapy was significantly more frequent in patients with ITD than in those without ITD (33.3% vs. 4.5%, P = 0.020), but was not significantly related to the presence of D835 mutations (28.6% vs. 5.9%, P = 0.094). Both ITD and D835 mutations were associated with shortened event-free survival (P = 0.048 and P = 0.029, respectively), but there was no correlation between disease-free survival among the 61 patients who achieved complete remission and the presence of FLT3 mutations (P = 0.543 for ITD and P = 0.277 for D835). FLT3 mutations were less frequent in Korean APL patients than in Western APL patients. In Korean patients, however, FLT3 mutations were associated with higher leukemic burdens and early deaths before remission resulting in inferior prognosis.

Differences in the Frequency of 23S rRNA Gene Mutations in Mycoplasma pneumoniae between Children and Adults with Community-Acquired Pneumonia: Clinical Impact of Mutations Conferring Macrolide Resistance

ABSTRACT We investigated the frequency and clinical significance of macrolide resistance in adult and pediatric patients with community-acquired pneumonia from a Mycoplasma pneumoniae infection. The frequency of the A2063G mutation in the 23S rRNA gene was significantly higher in children than in adults (61.3% [19/31] and 13.3% [8/60], respectively; P < 0.001). Patients with macrolide-resistant M. pneumoniae infections showed a longer duration of fever (P = 0.021) and required a longer duration of antibiotic treatment (P = 0.007).

Frequent Detection of Pandemic (H1N1) 2009 Virus in Stools of Hospitalized Patients

A novel subtype of influenza A virus called pandemic (H1N1) 2009 virus showed global outbreaks in 2009. Previous studies reported that gastrointestinal symptoms such as diarrhea, vomiting, and abdominal pain were frequent in patients with pandemic (H1N1) 2009 virus infection (3, 4, 5). However, the frequency of viral shedding in this pandemic (H1N1) 2009 virus infection was not well known. We recovered pandemic (H1N1) 2009 virus from stools of hospitalized H1N1-positive patients. From 10 November to 31 December 2009, 1,774 patients were diagnosed as having pandemic (H1N1) 2009 virus infections by real-time reverse transcription-PCR (RT-PCR) from nasopharyngeal swab samples in a tertiary-care hospital located in Seoul, South Korea. Among them, 96 patients required hospitalization due to progression to pneumonia or febrile convulsion, acute gastroenteritis, or underlying illnesses. Their stool samples were requested to be collected at admission, irrespective of gastrointestinal symptoms. A total of 65 patients submitted their stool samples at 0 to 8 days after the onset of flu symptoms and were included in this study (Table ​(Table1).1). Twelve patients (18.5%) complained of diarrhea during the hospitalization period. All of them were self-limited, and only one patient showed a pathogen, Salmonella group B, in routine stool cultures. This study was approved by the Sanggye Paik Hospital institutional review board. TABLE 1. Demographic characteristics categorized by the presence of viral RNA in stools among the study population hospitalized with pandemic (H1N1) 2009 virus Viral RNA in stool was isolated using the QIAamp virus RNA minikit (Qiagen, Crawley, United Kingdom). Pandemic (H1N1) 2009 virus was detected by two kinds of RT-PCR kits, the Anyplex FluA new H1N1 kit (SeeGene, Seoul, South Korea) and TaqMan Influenza A MGB assays (Applied Biosystems). Pandemic (H1N1) 2009 virus was recovered from stools of 16 patients (24.6%). Nine of them (56.3%) did not complain of any gastrointestinal symptoms during hospitalization. Only 4 patients simultaneously presented diarrhea and fecal excretion of pandemic (H1N1) 2009 virus. Comparing stool pandemic (H1N1) 2009-positive and -negative groups, no difference of frequency was noticed for diarrhea (P = 0.683), nausea (P = 0.746), vomiting (P = 0.898), and abdominal pain (P = 0.977) (Table ​(Table11). The clinical significance and pathophysiology of fecal influenza A virus excretion are not yet clear (1, 9). However, avian influenza A (H5N1) virus has been known to cause severe gastrointestinal manifestations and to replicate in human intestinal tissues (2, 7, 8). To et al. detected pandemic (H1N1) 2009 virus in stool from 4 of 9 patients with positive viral culture from the specimen with the highest viral load (6). This finding suggested the fecal shedding of viable pandemic (H1N1) 2009 virions. In this study, fecal excretion of pandemic (H1N1) 2009 virus was not correlated with the presence of gastrointestinal symptoms as described for avian influenza A (H5N1) virus (7). This study has some limitations: outpatients were not included and virus cultures and quantifications were not performed. However, our data show that considerable numbers of patients shed pandemic (H1N1) 2009 virus in their stool, even in the absence of diarrhea. The frequent detection of fecal pandemic (H1N1) 2009 virus excretion deserves attention in the study of infection control to prevent viral dissemination.

Role of horizontal transfer of the transposon Tn1546 in the nosocomial spread of vanA vancomycin-resistant enterococci at a tertiary care hospital in Korea.

OBJECTIVE To investigate the epidemiologic characteristics of vancomycin-resistant enterococci (VRE) infection. DESIGN An epidemiologic description by means of chromosomal DNA fingerprinting and transposon typing. SETTING A 2,200-bed tertiary care hospital in Korea. PATIENTS First VRE isolates were obtained from patients hospitalized from April 1997 to December 2001. INTERVENTIONS The van genotypes of isolates were identified by means of multiplex polymerase chain reaction (PCR). The macrorestriction patterns of chromosomal DNA were determined by pulsed-field gel electrophoresis (PFGE). The transposon Tn1546 was typed by means of 2 sets of long PCR restriction fragment-length polymorphism analysis, which were ClaI restriction of a 10.4-kb region from orf1 to vanZ and DdeI restriction of a 4.4-kb region from vanR to vanX. RESULTS VRE isolates were recovered from 215 patients. All were vanA genotype. PFGE analysis of the 215 isolates showed 172 types, including 21 clusters composed of 64 isolates and 151 types of as many isolates. Each type was composed of 2-10 isolates; the isolates within each PFGE cluster were detected within a 10-month period and mostly shared a transposon type. Transposon typing classified 169 strains into 15 types and 158 strains belonged to 4 major transposon clusters. Each of these 4 transposon clusters was isolated from patients treated in 5-22 different wards during a 31-52 month period and consisted of 9-80 PFGE types. Each of the other 11 types were found in only one strain. CONCLUSIONS Our findings suggest that the horizontal transfer of Tn1546 has a major role in the nosocomial spread of vanA VRE. Clonal spread of VRE seemed to contribute to short-term dissemination in limited areas.

Evaluation of four commercial IgG- and IgM-specific enzyme immunoassays for detecting Mycoplasma pneumoniae antibody: comparison with particle agglutination assay.

Diagnosis of Mycoplasma pneumoniae infection is important due to its variable clinical manifestations and absence of response to beta-lactams. Introduction of enzyme immunoassays (EIAs) for serologic diagnosis of M. pneumoniae has made it possible to separate the analyses of specific IgG and IgM antibodies. We compared four different commercial EIAs, ImmunoWELL IgG, IgM (GenBio), Medac IgG, IgA, IgM (Medac), Platelia IgG, IgM (Sanofi Pasteur), and Ridascreen IgG, IgA, IgM (r-Biopharm) with indirect particle agglutination assay (PA), Serodia-MycoII (Fujirebio). We tested 91 specimens from 73 pediatric patients (2-17 yr) hospitalized at a tertiary-care hospital between December 2005 and January 2006. The measurements of IgM EIAs were correlated with PA titers (Spearmans correlation coefficient, from 0.89 to 0.92) with high concordance rates, ranging from 82.4% to 92.3%. However, some negative IgM-EIA results in PA-positive specimens indicated that serial samplings with convalescent sera would be necessary to confirm M. pneumoniae infection.

Comparison of BD GeneOhm Cdiff and Seegene Seeplex ACE PCR Assays Using Toxigenic Clostridium difficile Culture for Direct Detection of tcdB from Stool Specimens

ABSTRACT We evaluated the performances of 2 PCR assays (BD GeneOhm and Seegene ACE) for direct detection of tcdB from stool specimens. The concordance rate between BD and Seegene was 96.3%. The sensitivities, specificities, positive predictive values (PPVs), and negative predictive values (NPVs) of BD and Seegene were 95.7%, 96.5%, 91.8%, and 98.2% and 90.0%, 97.1%, 92.6%, and 96.0%, respectively.

Comparison of VIDAS CDAB and CDA immunoassay for the detection of Clostridium difficile in a tcdA- tcdB+ C. difficile prevalent area.

Enzyme immunoassays for TcdA and/or TcdB are widely used for diagnosis of C. difficile infection. This study compared the performance of the new VIDAS C. difficile Toxin A & B assay (CDAB) with that of the existing VIDAS C. difficile Toxin A II assay (CDA) in a tcdA(-)tcdB(+) prevalent area. A total of 555 fecal samples were cultured and tested using CDAB and CDA. C. difficile was isolated in 150 samples and the concordance rate was 81.8% (454/555) between CDAB and CDA. PCR assays for tcdA and/or tcdB were used as a confirmatory test on C. difficile strains recovered from culture positive cases (n=150) and on fecal specimens in culture negative/CDAB positive or equivocal cases (n=27). The number of tcdA(+)tcdB(+), tcdA(-)tcdB(+), and tcdA(-)tcdB(-) strains on culture positive isolates (n=150) were 75 (50.0%), 41 (27.3%), and 34 (22.7%), respectively. PCR assays for tcdB gene alone in stool specimens (n=27) showed positivity in five cases. The sensitivity of VIDAS CDAB was higher than that of VIDAS CDA (65.3% vs. 29.8%), by more than 2-fold. The specificity of CDAB was almost the same as CDA (93.8% vs. 94.5%). Toxigenic culture of C. difficile isolates in culture positive/VIDAS CDAB negative cases (n=62) additionally detected 22 VIDAS CDAB positive and 9 VIDAS CDAB equivocal cases. The VIDAS CDAB assay detects more tcdA(+)tcdB(+) strains (60% vs. 45.3%) and tcdA(-)tcdB(+) strains (70.7% vs. 0%) compared with VIDAS CDA.

Evaluation of the Elecsys® Anti-HCV II assay for routine hepatitis C virus screening of different Asian Pacific populations and detection of early infection

BACKGROUND Early diagnosis of hepatitis C virus (HCV) infection is essential to allow appropriate treatment and prevent transmission. OBJECTIVES To evaluate the Elecsys(®) Anti-HCV II assay as a routine screening assay in Asia using a large number of samples from different Asian Pacific populations and compare its performance with other HCV assays routinely used in the region. STUDY DESIGN The sensitivity and specificity of the Elecsys(®) Anti-HCV II assay were determined using routine hospital samples and compared with at least one of the following comparator assays at nine independent centers: ARCHITECT™ Anti-HCV; Serodia(®)-HCV Particle Agglutination; Vitros(®) ECi Anti-HCV; Elecsys(®) Anti-HCV; ADVIA Centaur(®) HCV; InTec(®) HCV EIA; or Livzon(®) Anti-HCV. Commercially available seroconversion panels were used to assess sensitivity for early detection of infection. RESULTS The Elecsys(®) Anti-HCV II assay was more sensitive in recognizing early infection and detected acute HCV infection earlier on average than the comparator assays for all six panels tested. 7,726 routine samples were tested and 322 identified as HCV positive. Elecsys(®) Anti-HCV II had a sensitivity of 100% and a specificity of 99.66%, both of which were comparable or superior to the results obtained for competitor assays, which ranged from 87.5-100% and 98.98-100%, respectively. CONCLUSIONS The Elecsys(®) Anti-HCV II assay has the sensitivity and specificity to support its use as a routine screening method in the Asia Pacific region. Furthermore, this assay shortens the diagnostic window between infection and the detection of antibodies compared with established methods.

Single-nucleotide polymorphism PCR for the detection of Mycoplasma pneumoniae and determination of macrolide resistance in respiratory samples☆

The aim of this study was to develop a single-nucleotide polymorphism (SNP) PCR assay to be performed directly on respiratory samples for the simultaneous detection of Mycoplasma pneumoniae and its 23S rRNA gene mutations, which are responsible for macrolide resistance. For multiplex SNP PCR, two outer primers for amplification of the 23S rRNA gene and two mutant-specific primers for the discrimination of single base changes were designed. A total of 73M. pneumoniae-positive samples and 100M. pneumoniae-negative samples were analyzed using this assay. By SNP PCR, we detected two mutations conferring high-level macrolide resistance in 22 samples (A2063G from 20 and A2064G from 2 samples); these results are identical to those produced by the 23S rRNA gene sequencing of M. pneumoniae-positive samples. Thus, this assay can be used as a practical method for the simultaneous detection of M. pneumoniae and mutations associated with macrolide resistance directly from respiratory samples.

A case of hemophagocytic syndrome complicated by acute viral hepatitis A infection

Hemophagocytic syndrome (HPS) is a rare but serious condition that is histopathologically characterized by activation of macrophage or histiocytes with hemophagocytosis in bone marrow and reticuloendothelial systems. Clinically it presents with high fever, hepatosplenomegaly, pancytopenia, liver dysfunction, and hyperferritinemia. Hepatitis A virus is a very rare cause of secondary HPS. We report a case of a 22-year-old woman infected by hepatitis A virus who was consequently complicated with HPS. She presented typical clinical features of acute hepatitis A, and showed clinical and biochemical improvements. However, HPS developed as a complication of acute hepatitis A and the patient died of intraperitoneal bleeding caused by hepatic decompensation and disseminated intravascular coagulation.