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Background: Helicobacter pylori infection in children causes gastrointestinal symptoms and iron deficiency anemia. This study aimed to investigate trends in H. pylori stool antigen (HpSA) positivity in children and the relationship between HpSA test results and anemia.Methods: We analyzed the results of 2,762 HpSA tests and the correlation of hemoglobin and ferritin with HpSA in patients aged 0-18 years from 2008 to 2014 at a tertiary care center. Additionally, we prospectively evaluated HpSA test results and correlation with hemoglobin in 352 specimens obtained from five centers.Results: From 2008-2014, the mean positive rate of the HpSA test was 5.8%, with a high of 9.1% in 2012 and a low of 2.3% in 2013. The positive rate correlated with age: 2.9% in 0-6-year-olds, 5.8% in 7-12-year-olds, and 10.6% in 13-18-year-olds (P

Human cytomegalovirus (CMV) infection has been a major concern in hematopoietic stem cell transplant recipients. Ganciclovir (GCV) resistance results mostly from mutations within the protein kinase UL97 gene. The three hot spots for GCV resistance (codons 460, 520, and 590-607) were well known. We describe a case of GCV-resistant CMV colitis caused by a 597-600 deletion in UL97 after haplo-identical peripheral blood stem cell transplantation (h-PBSCT) in a 46 year-old man with myelodysplastic syndrome. On post-PBSCT day 28, CMV antigenemia turned positive. Treatment of GCV was started and continued for 12 weeks but CMV antigenemia did not respond to the treatment and CMV colitis was worsened. The UL97 showed the in-frame deletion between codons 597 and 600 by direct sequencing. The treatment was switched to foscarnet and the antigenemia test was consecutively negative twice, and clinical symptoms improved. Despite the recovery of the patient from CMV colitis, the patient expired post-PBSCT day 146 from acute liver failure, hepatorenal syndrome and septic shock. This case is a first report of a deletion 597-600 in CMV UL97 in Korea. A 597-600 deletion in UL97 was responsible for the GCV resistance while preserving susceptibility to foscarnet. (Ann Clin Microbiol 2015;18:64-67)

Background: Blood culture for diagnosis of bacter- emia and fungemia comprises aerobic and anaerobic cultures. The clinical utility of routine anaerobic blood culture has been questioned for a long time and was evaluated in this study. Methods: A total of 9,028 positive blood cultures were collected...

Background: Streptococcus agalactiae (Group B streptococcus, GBS) is known to be the leading cause of neonatal sepsis and meningitis in the United States and Europe. In addition, GBS infection has been increasingly noted in adults, particularly in those with underlying diseases, such as diabetes mellitus, malignancy and liver disease. A few studies reported that resistances to antibiotics, such as erythromycin, clindamycin, tetracycline are increasing. We report clinical and microbiological characteristics of GBS bacteremic patients in Jeju Island. Methods: We retrospectively analyzed medical records, such as age, sex, underlying disease, mortality, skin defects, laboratory results and antibiotic resistances of GBS in hospitalized adult patients who were diagnosed with GBS bacteremia from 2008 to 2013 in Jeju Island. Results: Twenty two adult patients were diagnosed as GBS bacteremia from 2008 to 2013. The mean age of GBS bacteremic patients was 66.2 years old. Of 22 bacteremic patients, fifteen patients (68%) were older than 60. Twenty patients (91%) of bacteremic patients had underlying diseases such as diabetes mellitus, malignancy and liver disease. Ten (45%) patients had skin defects which were on the lower extremities and buttock, fifteen (68%) patients had fever at the time of admission, twenty one (95%) patients were admitted via the emergency department. Two (9%) patients died. The mean white blood cell (WBC) count, percentile of neutrophil count, and C-reactive protein (CRP) levels were 11,488/μL, 84.3 %, 13.5 mg/dL respectively. All GBS isolates from bacteremia showed sensitivities to penicillin, ampicillin, and vancomycin, and showed resistances to erythromycin (25%), clindamycin (30%), and tetracycline (55%). Conclusion: Bacteremia caused by GBS was prevalent in adult patients with underlying diseases. Most of the GBS bacteremic patients were emergency cases, with a high body temperature, WBC, CRP level, and neutrophil count. Half of them had skin defects, which are considered a source of GBS bacteremia. (Ann Clin Microbiol 2014;17:9-13)

Department of Laboratory Medicine, Chonnam National University Medical School, Gwangju, Kyungpook National University of Medicine, Daegu, Chungnam National University of Medicine, Daejeon, Pusan National University Yangsan Hospital, Yangsan, The Catholic University of Korea College of Medicine, Seoul, Ajou University School of Medicine, Suwon, Yonsei University Wonju College of Medicine, Wonju, Chung-Ang University College of Medicine, Seoul, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Chonbuk National University Medical School, Jeonju, Yonsei University College of Medicine, Seoul, Korea

Background: Although many laboratories use automated blood culture systems, adequate skin disinfection and optimal blood volume are still critical for successful culture. The authors undertook a nationwide survey to understand the current situation and problems of blood culture in Korea. Methods: A survey of blood culture was performed in March and April 2010, including disinfectants, blood collection intervals, and recommended blood volumes. The laboratory physicians described the storage condition of culture bottles before delivery to the equipment. For quality control, the positive rate and skin contamination rate were studied. Results: Replies to the survey were collected from 74 Korean hospitals. Povidone iodine after either isopropyl alcohol or ethanol application was the most common means of skin disinfection. Sampling of a second set of cultures was performed simultaneously in 38% of hospitals and after a 30-min interval in 50%. The recommended blood volume was 10 mL in most cases (69%), but was 20 mL in 24% of cases. The bottles were stored at 37C before installation in 23% of cases and at room temperature in 16%, whereas 57% were placed directly in the equipment during the night shift. Positive rates ranged 8-10% in 32% of hospitals, 5-8% in 23%, and 3% in 13%. Conclusion: Skin disinfection methods were rather variable. Sampling interval, blood volume, and storage of bottles should be standardized. More than 10% of the hospitals require quality improvement in terms of positive rate and skin contamination rates. (Korean J Clin Microbiol 2011;14:91-96)

Cryptococcus is an opportunistic pathogen that mainly affects immunocompromised hosts and, less frequently, immunocompetent hosts. It causes serious morbidity and mortality due to systemic infections such as meningoencephalitis and pulmonary infection. Urinary involvement of Cryptococcus is sometimes reported among cases of disseminated cryptococcosis in AIDS patients, but no such reports have been published in Korea. We report two cases of cryptococcuria that developed in a 71-year old female with diabetes and liver cirrhosis and in a 50-year old male who received a liver transplant due to HBV-associated hepatic failure. The female patient had received prednisolone for 12 days before we detected C. neoformans in urine culture. Even though no antifungal therapy was indicated for cryptococcuria, following urine culture became negative, but still positive for cryptococcal antigen on hospital day 25. Her blood, CSF culture, and antigen tests were negative, and therefore she was diagnosed with isolated cryptococcuria. The male patient had received prednisolone and tacrolimus for 10 days before sputum and urine cultures became positive for C. neoformans. He had ill defined nodules and pleural effusion in both lungs on chest CT. His cryptococcuria was sustained for over 2 months, despite receiving amphotericin B treatment. His cryptococcuria seemed to be a symptom of disseminated cryptococcosis. (Korean J Clin Microbiol 2011;14:148-152)

Background: Causative bacterial agents of infectious diarrheal disease were traditionally diagnosed by stool cultures. Stool culture, however, has a problem because of relatively low sensitivity and long turnaround time. In this study, we evaluated multiplex PCR applied on stool specimens directly to diagnose enteropathogenic bacteria. Methods: From June to September 2009, 173 diarrheal stools submitted for stool cultures were tested by SeeplexR Diarrhea ACE Detection kit (Seegene, Korea) to detect 10 enteropathogenic bacteria. Specimens were cultured for Salmonella, Shigella, Vibrio, and Yersinia. Late 50 specimens were also cultured for Campylobacter. The specimens positive for verotoxin-producing Escherichia coli (VTEC) were further subcultured for detecting enterohaemorrhagic Escherichia coli O157:H7. Electronic medical records were reviewed for clinical and laboratory findings. Results: Of 173 specimens, multiplex PCR and cultures identified enteropathogens in 36 (20.8%) and 8 specimens (4.6%), respectively. While multiplex PCR detected 5 Salmonella, 15 Campylobacter, 1 Vibrio, 4 Clostridium difficiles toxin B, 5 Clostridium perfringens, 1 Yersinia enterocolitica, 5 Aeromonas, and 2 VTEC, cultures detected 5 Salmonella, 1 Vibrio, 1 Y. enterocolitica, 1 Aeromonas, and 2 E. coli O157:H7. Conclusion: Multiplex PCR would be useful to detect Campylobacter, VTEC and C. perfringens, as well as have equivalent sensitivity to conventional culture for ordinary enteropathogens such as Salmonella, Shigella, Vibrio, Y. enterocolitica. Direct application of multiplex PCR combined with conventional cultures on stool warrants remarkable improvement of sensitivity to diagnose enteropathogenic bacteria. (Korean J Clin Microbiol 2010;13:162-168)

Enterohemorrhagic Escherichia coli (EHEC) is an important cause of bloody diarrhea in children, but is considered to be rare in infants. Herein, a case of infant hemorrhagic colitis of verotoxin-producing E. coli O157:H7 diagnosed by multiplex PCR is reported. A nine-month-old boy was admitted to our hospital with bloody diarrhea for the previous two days. Multiplex PCR using SeeplexR Diarrhea ACE Detection Kit (Seegene, Seoul, Korea) was directly applied to the stool specimens. Amplified bands specific for verotoxin, O157, and H7 indicated the presence of O157:H7 EHEC. The stool specimens were inoculated on sorbitol-MacConkey agar (SMA) and tryptic soy broth containing mitomycin C (TSB-M). Colorless colonies on sorbitol-MacConkey agar were O157-positive. TSB-M enrichment cultures of the stool specimen and the isolates were positive for verotoxin according to an enzyme immunoassay (EIA). The prepared ingredients of baby foods for the patient including ground meat, chopped carrot, chopped cabbage, and white rice porridge showed no EHEC on TSB-M and SMA. The patient’s parents and three-year-old sister did not recently have any gastrointestinal symptoms. Cefdinir was administered for one day and was ceased after diagnosis of EHEC colitis. The stool culture and verotoxin assay were negative on the second day of hospitalization. Application of multiplex PCR and verotoxin EIA directly to diarrheal stool warrants the rapid diagnosis and appropriate treatment of EHEC colitis. (Korean J Clin Microbiol 2010;13:85-89)

Background: We evaluated multiplex PCR for species identification and toxin typing to improve the sensitivity and turnaround time of toxigenic Clostridium difficile culture (TCDC). Methods: We performed multiplex PCR using primers targeting the species-specific gene, tpi, and the toxin genes, tcdA and tcdB. From January to March 2008, 528 stool specimens were tested with direct toxin assay (DT) using C. difficile Tox A/B II (Techlab, Blacksburg, USA) and TCDC. For 288 specimens from early study period, toxin production by C. difficile isolates of TCDC was measured by enzyme immunoassay with culture supernatants using VIDAS C. difficile Toxin AB bioMerieux, Marcy-l'Etoile, France) and multiplex PCR with isolated colonies. For 240 specimens from late period, only multiplex PCR was used to test toxin production by the isolates. Results: During the early period, 29 C. difficile were isolated and their toxin-positive rates were 65.5% by PCR and 44.8% by CDAB (P＜0.05). Among 528 stool specimens, the results of DT+/TCDC+, DT+/ TCDC-, and DT-/TCDC+ were 32 (6.1%), 33 (6.3%), and 10 (1.9%), respectively, when tested with PCR. 13.3% of total 75 positive specimens was detected only by TCDC. Of the 42 toxigenic C. difficile isolates, all were positive for tpi, 30 (71.4%) were tcdA+/tcdB+, and 12 (28.6%) were tcdA-/tcdB+. Conclusion: TCDC using multiplex PCR for species identification and toxin typing is sensitive and rapid to be used as a routine diagnostic test. (Korean J Clin Microbiol 2009;12:11-16)

Background: CLSI provides a guideline only for a agar dilution method of testing clarithromycin susceptibility for Helicobacter pylori. This study was to evaluate a disk diffusion method for clarithromycin and amoxicillin. Methods: One hundred and forty clinical isolates of H. pylori isolated from May 2005 to May 2007 were tested by the CLSI agar dilution method and a disk diffusion method using 2μg (2CLR) and 15μg (15CLR) clarithromycin disks and 2μg (2AMX) and 10μg (10AMX) amoxicillin disks. The interpretation criteria used for the disk diffusion method were established by linear regression and error rate-bounded method for disk diffusion zone of inhibition (DDZ) compared to MIC. Results: Resistance and intermediate rates to clarithromycin were 21.4% and 1.4%, respectively. A number of isolates with MIC 0.5, 1, and 2 (μg/mL) to amoxicillin were 7, 2, and 1, respectively. For 2CLR and 15CLR, the coefficients of determination (R) between MIC and DDZ were 0.931 and 0.923 (P< 0.001), respectively, and the criteria for resistance/ susceptibility were 12/28 mm for 2CLR and 23/39 mm for 15CLR. For 2AMX and 10AMX, the R between MIC and DDZ were 0.478 and 0.421 (P< 0.001), respectively, and the criteria for resistance with breakpoint of 2μg/mL were 21 mm for 2AMX and 32 mm for 10AMX. All isolates had DDZ

Background: Clarithromycin resistance in Helicobacter pylori is a major cause of eradication therapy failure. The objective of this study was to determine the frequency and type of mutations in the 23S rRNA gene in Korea, which are associated with clarithromycin resistance. Methods: From January 2008 to March 2008, 353 gastric biopsy specimens were collected from five university hospitals in Seoul and Kyunggido. H. pylori infection was defined as showing a positive result in at least one of the following three tests: a microaerophilic culture, a CLO test, and a Giemsa/silver stain. The frequencies of A2143G, A2142G, and the wild type of 23S rRNA and the presence of H. pylori were determined by Seeplex ClaR-H. pylori PCR (Seegene Inc., Seoul, Korea). Twenty-nine culture isolates were tested for susceptibility to clarithromycin by E-test (AB Biodisk, Solna, Sweden) or the CLSI (Clinical and Laboratory Standards Institute) disk diffusion test. Results: From 176 H. pylori PCR-positive specimens, 23S rRNA gene mutations were detected in 38 isolates (21.6%), including 27 isolates of A2143G and 11 isolates of A2142G. Total mutation rates varied from 15.8% to 31.3% with the frequency of A2143G mutation alone varying from 8.5% to 25.0% among the five hospitals studied. There were 10 clarithromycin-resistant isolates found by susceptibility test and they were all positive for A2143G mutation. But, 3 of the 19 susceptible isolates were also positive for either A2143G or A2142G mutation. Conclusion: In Korea, the overall frequency of clarithromycin-resistant H. pylori was 21.6%; however, the type and frequency of the 23S rRNA mutations varied from hospital to hospital. (Korean J Clin Microbiol 2008;11:84-89)