Establishment of Pediatric Reference Intervals for Routine Laboratory Tests in Korean Population: A Retrospective Multicenter Analysis

Background@#Reference intervals defined for adults or children of other ethnicities cannot be applied in the evaluation of Korean pediatric patients. Pediatric reference intervals are difficult to establish because children are in their growing stage and their physiology changes continuously. We aimed to establish reference intervals for routine laboratory tests for Korean pediatric patients through retrospective multicenter data analysis. @*Methods@#Preoperative laboratory test results from 1,031 pediatric patients aged 0 month–18 years who underwent minor surgeries in four university hospitals were collected. Age- and sex-specific reference intervals for routine laboratory tests were defined based on the Clinical and Laboratory Standards Institute (CLSI) EP28-A3c guidelines. @*Results@#The pediatric reference intervals determined in this study were different from existing adult reference intervals and pediatric reference intervals for other ethnicities. Most tests required age-specific partitioning, and some of those required sex-specific partitioning for at least one age-partitioned subgroup. Erythrocyte sedimentation rate, monocyte percentage, basophil percentage, activated partial thromboplastin time, glucose, cholesterol, albumin, bilirubin, chloride, and C-reactive protein did not show any difference between age- or sex-partitioned subgroups. @*Conclusions@#We determined Korean pediatric reference intervals for hematology, coagulation, and chemistry tests by indirect sampling based on medical record data from multiple institutions. These reference intervals would be valuable for clinical evaluations in the Korean pediatric population.

Utility of Conventional Culture and MALDI-TOF MS for Identification of Microbial Communities in Bronchoalveolar Lavage Fluid in Comparison with the GS Junior Next Generation Sequencing System

BACKGROUND: Diverse microbiota exist in the lower respiratory tract. Although next generation sequencing (NGS) is the most widely used microbiome analysis technique, it is difficult to implement NGS in clinical microbiology laboratories. Therefore, we evaluated the performance of conventional culture methods together with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) in identifying microbiota in bronchoalveolar lavage (BAL) fluid. METHODS: BAL fluid samples (n=27) were obtained from patients undergoing diagnostic bronchoscopy for lung mass evaluation. Bacterial and fungal culture was performed with conventional media used in clinical microbiology laboratories. On an average, 20 isolated colonies were picked from each agar plate and identified by MALDI-TOF MS. Microbiome analysis using 16S rRNA NGS was conducted for comparison. RESULTS: Streptococcus spp. and Neisseria spp. were most frequently cultured from the BAL fluid samples. In two samples, Enterobacteriaceae grew predominantly on MacConkey agar. Actinomyces and Veillonella spp. were commonly identified anaerobes; gut bacteria, such as Lactobacillus, Bifidobacterium, and Clostridium, and fungi were also isolated. NGS revealed more diverse bacterial communities than culture, and Prevotella spp. were mainly identified solely by NGS. Some bacteria, such as Staphylococcus spp., Clostridium spp., and Bifidobacterium spp., were identified solely by culture, indicating that culture may be more sensitive for detecting certain bacteria. CONCLUSIONS: Culture and NGS of BAL fluid samples revealed common bacteria with some different microbial communities. Despite some limitations, culture combined with MALDI-TOF MS might play a complementary role in microbiome analysis using 16S rRNA NGS.

Comparison of a New Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry Platform, ASTA MicroIDSys, With Bruker Biotyper for Species Identification

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, with its accuracy and speed, is widely used for bacterial identification. The ASTA MicroIDSys system (ASTA, Korea) was recently developed for species identification. We compared its performance with that of Bruker Biotyper (Bruker Daltonics, Germany). Microbes were recovered from sputum, urine, and pus samples from patients admitted to a tertiary care hospital in Korea from January to April 2016. Matrix solution (α-cyano-4-hydroxycinnamic acid) was used, and the peptide profiles acquired from the Microflex LT (Bruker Daltonics) and Tinkerbell LT (ASTA) were analyzed by using their respective software. From 5,322 isolates, Bruker Biotyper identified 163 species; fifty species from 4,919 isolates were identified more than 10 times, including Klebsiella pneumoniae (n=571), Acinetobacter baumannii (n=436), Pseudomonas aeruginosa (n=358), Escherichia coli (n=372), Staphylococcus aureus (n=511), S. epidermidis (n=444), Enterococcus faecium (n=262), E. faecalis (n=220), and Candida albicans (n=248). Identical results, confidence scores (≥ 2.0 for Bruker Biotyper), and acceptable scores (≥140 for ASTA MicroIDSys) were obtained for 86.1% of isolates. Of 4,267 isolates, 99.2% showed acceptable scores in both systems. Results from the ASTA MicroIDSys showed good agreement with those from the Bruker Biotyper. The ASTA MicroIDSys could reliably identify clinically important microorganisms.

Changing Guidelines for Clinical Microbiology Laboratories and Their Influences on Workflows Related to Consultations

BACKGROUND: Since the concept of 'minimal identification of poor quality specimens or microbes with low pathogen potential' has been introduced into the standard operating procedure (SOP) to enhance work efficiency, consultations are requested for further species identification and antimicrobial susceptibility testing. The aim of this study was to evaluate the impact of consultations requests to the clinical microbiology laboratory on its work efficiency. METHODS: From January 2013 to April 2015, consultation requests to the laboratory in a tertiary-care hospital were collected from electronic medical records. The characteristics of consultations and changes to workflow due to the laboratory SOP amendment were analyzed. Turnaround time of the consultation and specimen culture were evaluated as an indicator of workflow efficiency. RESULTS: A total of 971 consultations were evaluated during the study period. The most common purposes for consultations were microbe species identification and antimicrobial susceptibility tests. Among the minimal identification reports, the proportions of consultations were below 5%. The number of consultations had increased substantially. However, the turnaround time of consultation and specimen culture showed declining trends. CONCLUSIONS: With the introduction of the consultation system, the workload for species identification and antimicrobial susceptibility testing of colonizing microbes could be minimized. This research provides an example of work efficiency management for laboratory procedures based on an SOP amendment.

Disk Carbapenemase Test for the Rapid Detection of KPC-, NDM-, and Other Metallo-β-Lactamase-Producing Gram-Negative Bacilli

BACKGROUND: Rapid detection of carbapenemase-producing gram-negative bacilli (GNB) is required for optimal treatment of infected patients. We developed and assessed a new disk carbapenemase test (DCT). METHODS: Paper disks containing 0.3 mg of imipenem and bromothymol blue indicator were developed, and the performance of the DCT were evaluated by using 742 strains of GNB with or without carbapenemases. RESULTS: The paper disks were simple to prepare, and the dried disks were stable at -20℃ and at 4℃. The DCT detected 212 of 215 strains (98.6% sensitivity with 95% confidence interval [CI] 96.0-99.5%) of GNB with known class A (KPC and Sme) and class B (NDM, IMP, VIM, and SIM) carbapenemases within 60 min, but failed to detect GES-5 carbapenemase. The DCT also detected all two Escherichia coli isolates with OXA-48, but failed to detect GNB with OXA-232, and other OXA carbapenemases. The DCT showed 100% specificity (95% CI, 99.2-100%) in the test of 448 imipenem-nonsusceptible, but carbapenemase genes not tested, clinical isolates of GNB. CONCLUSIONS: The DCT is simple and can be easily performed, even in small laboratories, for the rapid detection of GNB with KPC, NDM and the majority of IMP, VIM, and SIM carbapenemases.

Molecular Epidemiology and Characterization of Carbapenemase-Producing Enterobacteriaceae Isolated at a University Hospital in Korea during 4-Year Period / 대한임상미생물학회지

BACKGROUND: Carbapenemase-producing Enterobacteriaceae (CPE) has been increasingly reported worldwide in the past 10 years, which is an important infection control concern. Since the epidemiology and characteristics of these CPEs vary according to institutes, we aimed to characterize CPEs in a university hospital during the recent 4 years. METHODS: From October 2011 to September 2015, CPE isolates from clinical specimens and hospital surveillance cultures were collected. Carbapenem resistance was confirmed by disk diffusion method and Minimal Inhibitory Concentration (MIC) was determined by agar dilution method. Carbapenemase production was tested by double disk test using aminophenylboronic acid and dipicolic acid. PCR and sequence analysis were performed to detect bla(KPC), bla(IMP-1), bla(VIM-2), bla(NDM-1)-like genes and bla(OXA-48) gene. Pulsed-field gel electrophoresis (PFGE) and Multilocus sequence typing (MLST) were conducted for KPC-producing Klebsiella pneumoniae isolates. RESULTS: Twenty-five isolates (11%) of CPE were identified among 222 carbapenem-resistant Enterobacteriacae isolates during the study period. The most prevalent CPE was KPC-producing K. pneumonia and others were IMP-1, VIM-2, NDM-1 type and OXA-48 producing CPEs. Most of these CPEs showed resistance to carbapenems with variable MICs. The sequence types (STs) of KPC-producing K. pneumoniae were ST307 and ST11. The PFGE of ST11 and ST307 showed clonality in each group suggesting the possibility of in-hospital outbreak. CONCLUSION: The prevalence of CPE has been increasing. In our institute, KPC-producing K. pneumoniae was the most frequently isolated CPE in the recent 4 years. CPE including KPC producers can easily transfer their resistance. Therefore continuous monitoring and more intensified infection control for CPE should be considered.

Flavobacterium ceti From Blood Samples of a Korean Patient With Alcoholic Liver Cirrhosis

No abstract available.

Large Deletion in KCNQ1 Identified in a Family with Jervell and Lange-Nielsen Syndrome

Long QT syndrome (LQTS) is a genetically heterogeneous disorder associated with sequence variations in more than 10 genes; in some cases, it is caused by large deletions or duplications among the main, known LQTS-associated genes. Here, we describe a 14-month-old Korean boy with congenital hearing loss and prolonged QT interval whose condition was clinically diagnosed as Jervell and Lange-Nielsen syndrome (JLNS), a recessive form of LQTS. Genetic analyses using sequence analysis and multiplex ligation-dependent probe amplification (MLPA) assay revealed a large deletion spanning exons 7-10 as well as a frameshift mutation (c.1893dup; p.Arg632Glnfs*20). To our knowledge, this is the first report of a large deletion in KCNQ1 identified in JLNS patients. This case indicates that a method such as MLPA, which can identify large deletions or duplications needs to be considered in addition to sequence analysis to diagnose JLNS.

The First Korean Case of Moraxella osloensis Bacteremia in a Patient with Acute Myeloid Leukemia

No abstract available.

First Case of Mycobacterium longobardum Infection

Mycobacterium longobardum is a slow-growing, nontuberculous mycobacterium that was first characterized from the M. terrae complex in 2012. We report a case of M. longobardum induced chronic osteomyelitis. A 71-yr-old man presented with inflammation in the left elbow and he underwent a surgery under the suspicion of tuberculous osteomyelitis. The pathologic tissue culture grew M. longobardum which was identified by analysis of the 65-kDa heat shock protein and full-length 16S rRNA genes. The patient was cured with the medication of clarithromycin and ethambutol without further complications. To the best of our knowledge, this is the first report of a M. longobardum infection worldwide.

A Case of Fatal Myocarditis Associated with Mycoplasma pneumoniae Pneumonia / 소아감염

Mycoplasma pneumoniae is a common cause of respiratory tract infections. And M. pneumoniae infection frequently manifests with extrapulmonary symptoms such as central nervous system complications, skin or mucosal involvement, and gastrointestinal problems. However, cardiac complications associated with M. pneumoniae are rarely reported. We report the case of a 47-month-old girl who died of fulminant myocarditis associated with M. pneumoniae pneumonia.

A Review of Staphylococcus aureus Infections in Children with an Emphasis on Community-associated Methicillin-resistant S. aureus Infections / 소아감염

PURPOSE: Staphylococcus aureus causes a variety of infections, ranging from benign skin infections to fatal invasive infections. Recently, methicillin-resistant S. aureus (MRSA) infections have emerged in patients who do not have established risk factors. This study was conducted to characterize S. aureus infections in children with an emphasis on community- associated MRSA infections at a tertiary care pediatric facility during a 3-year period. METHODS: Four hundred twenty-nine cases of S. aureus infections diagnosed at the Seoul National University Children's Hospital between January 2004 and December 2006 were retrospectively reviewed. The cases were classified as hospital- onset (HO) or community-onset (CO), healthcare-associated (HA), or community-associated (CA) infections. RESULTS: Among the 206 cases 1 year of age. The proportion of CO-HA infections among HA infections (8.6% vs. 37.1%, P<0.001) and the proportion of HA infections among the CO infections (24.5% vs. 54.3%, P<0.001) were greater in older children than in infants. Overall, 57% of the isolates were methicillin-resistant. Twenty-nine (30%) of 96 CA strains were MRSA, and the most common site of CA-MRSA infection was the skin and soft tissues (26 cases). CONCLUSION: The methicillin resistance rate of S. aureus from CA infections was high and CA-MRSA was most often associated with skin and soft tissue infections.

A Case of Hyperinsulinism/hyperammonemia Syndrome / 대한소아내분비학회지

The hyperinsulinism/hyperammonemia (HI/HA) syndrome is a form of congenital hyperinsulinism. The children with HI/HA syndrome present recurrent symptomatic hypoglycemia and asymptomatic, persistent hyperammonemia, caused by mutations of the GLUD1 encoding the mitochondrial enzyme, glutamate dehydrogenase (GDH). The mutations impair sensitivity to the inhibition of GTP (guanosine triphosphate), which results in stimulation of insulin secretion from pancreatic beta-cells and increased rates of ammonia production. Leucine is known to mediate the insulin secretion. We report HI/HA syndrome with a 12-month-old male who had intermittent hypoglycemia. We revealed characteristic clinical findings of hypoglycemia induced by oral administration of protein in this patient who had mutations of GLUD1 (S445L).