Background: Streptococcus pneumoniae is a serious pathogen causing various infections in humans. We evaluated the serotype distribution and antimicrobial resistance of S. pneumoniae causing invasive pneumococcal disease (IPD) after introduction of pneumococcal conjugate vaccine (PCV)13 in Korea and investigated the epidemiological characteristics of multidrug-resistant (MDR) isolates. Methods: S. pneumoniae isolates causing IPD were collected from 16 hospitals in Korea between 2017 and 2019. Serotyping was performed using modified sequential multiplex PCR and the Quellung reaction. Antimicrobial susceptibility tests were performed using the broth microdilution method. Multilocus sequence typing was performed on MDR isolates for epidemiological investigations. Results: Among the 411 S. pneumoniae isolates analyzed, the most prevalent serotype was 3 (12.2%), followed by 10A (9.5%), 34 (7.3%), 19A (6.8%), 23A (6.3%), 22F (6.1%), 35B (5.8%), 11A (5.1%), and others (40.9%). The coverage rates of PCV7, PCV10, PCV13, and pneumococcal polysaccharide vaccine (PPSV)23 were 7.8%, 7.8%, 28.7%, and 59.4%, respectively. Resistance rates to penicillin, ceftriaxone, erythromycin, and levofloxacin were 13.1%, 9.2%, 80.3%, and 4.1%, respectively. MDR isolates accounted for 23.4% of all isolates. Serotypes 23A, 11A, 19A, and 15B accounted for the highest proportions of total isolates at 18.8%, 16.7%, 14.6%, and 8.3%, respectively. Sequence type (ST)166 (43.8%) and ST320 (12.5%) were common among MDR isolates. Conclusions Non-PCV13 serotypes are increasing among invasive S. pneumoniae strains causing IPD. Differences in antimicrobial resistance were found according to the specific serotype. Continuous monitoring of serotypes and antimicrobial resistance is necessary for the appropriate management of S. pneumoniae infections.

Background: This study aimed to evaluate the diagnostic performance of the STANDARD F Influenza A/B FIA test (SD Biosensor Inc., Korea) for the rapid detection of influenza A virus in comparison with the Sofia Influenza A+B FIA (Quidel Corp., USA) and SD BIOLINE Influenza Ag A/B/A(H1N1) (Standard Diagnostic, Inc., Korea) tests. Methods: A total of 227 non-duplicated nasopharyngeal aspirates submitted for real-time RT-PCR analysis were included in the study. We used the three commercial tests in remnant samples from routine assays, according to the manufacturer’s instructions. We analyzed the diagnostic performance, including sensitivity and specificity, of the three tests. Results: Real-time RT-PCR analysis showed that 67 (29.5%) samples were positive and 160 (70.5%) were negative for influenza A virus, and that all the specimens were negative for influenza B. The overall sensitivity and specificity for influenza A virus detection were 50.7% and 100% for the STANDARD F, 50.7% and 100% for the Sofia, and 29.9% and 100% for the SD BIOLINE tests, respectively. The STANDARD F and SD BIOLINE tests showed negative results for influenza B virus in all specimens, whereas the Sofia test showed two false-positive results. Conclusion The STANDARD F Influenza A/B test showed a good diagnostic performance and may be useful for the rapid diagnosis of influenza A.

BACKGROUND: Salmonella is an important pathogen that causes gastroenteritis and sepsis in humans. Recently, changes in serotype prevalence and an increase in antimicrobial resistance have been reported. This study investigated the distribution of Salmonella serotypes and determined the antimicrobial susceptibility of various strains. METHODS: We collected 113 Salmonella isolates other than Salmonella serotype Typhi from 18 university hospitals in 2015. The serotypes were identified by Salmonella antisera O and H according to the Kauffman White scheme. Antimicrobial susceptibility tests for 12 antibiotics were performed using the disk diffusion method or E-test. RESULTS: We identified 22 serotypes. Serotype group B (44.2%) was the most common, followed by groups C (34.5%) and D (21.2%). Salmonella I 4,[5],12:i:- (23.0%), S. Enteritidis (16.8%), and S. Typhimurium (12.4%) were the most common species. Resistance rates for ampicillin, chloramphenicol, ceftriaxone, and trimethoprim/sulfamethoxazole were 46.9%, 18.5%, 8.8%, and 5.3%, respectively. The intermediate resistance rate to ciprofloxacin was 29.2%. Six isolates were extended-spectrum β-lactamase (ESBL) producers, including 5 bla(CTX-M-15) and 1 bla(CTX-M-55). CONCLUSION: There have been changes in the serotype prevalence and antimicrobial resistance of Salmonella in Korea, with a high prevalence of CTX-M 15-positive strains. Continuous monitoring of Salmonella serotypes and antimicrobial resistance is warranted.
Ampicillin ; Anti-Bacterial Agents ; Ceftriaxone ; Chloramphenicol ; Ciprofloxacin ; Diffusion ; Gastroenteritis ; Hospitals, University ; Humans ; Immune Sera ; Korea ; Methods ; Prevalence ; Salmonella ; Sepsis ; Serogroup ; Serotyping

BACKGROUND: Several factors contribute to differences in Streptococcus pneumoniae serotype distribution. We investigated the serotype distribution and antimicrobial resistance of S. pneumoniae isolated between 2014 and 2016 in Korea. METHODS: We collected a total of 1,855 S. pneumoniae isolates from 44 hospitals between May 2014 and May 2016, and analyzed the serotypes by sequential multiplex PCR. We investigated the distribution of each serotype by patient age, source of the clinical specimen, and antimicrobial resistance pattern. RESULTS: The most common serotypes were 11A (10.1%), followed by 19A (8.8%), 3 (8.5%), 34 (8.1%), 23A (7.3%), and 35B (6.2%). The major invasive serotypes were 3 (12.6%), 19A (7.8%), 34 (7.8%), 10A (6.8%), and 11A (6.8%). Serotypes 10A, 15B, 19A, and 12F were more common in patients ≤5 years old, while serotype 3 was more common in patients ≥65 years old compared with the other age groups. The coverage rates of pneumococcal conjugate vaccine (PCV)7, PCV10, PCV13, and pneumococcal polysaccharide vaccine 23 were 11.8%, 12.12%, 33.3%, and 53.6%, respectively. Of the 1,855 isolates, 857 (46.2%) were multi-drug resistant (MDR), with serotypes 11A and 19A predominant among the MDR strains. The resistance rates against penicillin, cefotaxime, and levofloxacin were 22.8%, 12.5%, and 9.4%, respectively. CONCLUSIONS: There were significant changes in the major S. pneumoniae serotypes in the community. Non-PCV13 serotypes increased in patients ≤5 years old following the introduction of national immunization programs with the 10- and 13-polyvalent vaccines.
Cefotaxime ; Humans ; Immunization Programs ; Korea ; Levofloxacin ; Multiplex Polymerase Chain Reaction ; Penicillins ; Pneumococcal Vaccines ; Pneumonia ; Serogroup ; Streptococcus pneumoniae ; Streptococcus ; Vaccines

BACKGROUND: The isolation of carbapenemase-producing Enterobacteriaceae (CPE) has become increasingly common. Continuous surveillance for these organisms is essential because their infections are closely related to outbreaks of illness and are associated with high mortality rates. The aim of this study was to develop and evaluate multiplex PCR as a means of detecting several important CPE genes simultaneously. METHODS: We aimed to develop a multiplex PCR that could detect seven CPE genes simultaneously. The multiplex PCR was composed of seven primer sets for the detection of KPC, IMP, VIM, NDM-1, GES, OXA-23, and OXA-48. We designed different PCR product sizes of at least 100 bp. We evaluated the performance of this new test using 69 CPE-positive clinical isolates. Also, we confirmed the specificity to rule out false-positive reactions by using 71 carbapenem-susceptible clinical strains. RESULTS: A total of 69 CPE clinical isolates showed positive results and were correctly identified as KPC (N=14), IMP (N=13), OXA-23 (N=12), OXA-48 (N=11), VIM (N=9), GES (N=5), and NDM (N=5) by the multiplex PCR. All 71 carbapenem-susceptible clinical isolates, including Enterococcus faecalis , Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa, showed negative results. CONCLUSION: This multiplex PCR can detect seven CPE genes at a time and will be useful in clinical laboratories.
Acinetobacter baumannii ; Disease Outbreaks ; Enterobacteriaceae ; Enterococcus faecalis ; Escherichia coli ; Klebsiella pneumoniae ; Mortality ; Multiplex Polymerase Chain Reaction ; Polymerase Chain Reaction ; Pseudomonas aeruginosa ; Sensitivity and Specificity

C. striatum is part of the normal skin and mucous membrane flora in humans and is widely disseminated in the environment. Traditionally, these strains have been considered contaminants. However, C. striatum has been linked to respiratory infection, bacteremia, and endocarditis; and it is strongly related to nosocomial outbreaks. At present, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF) is the most accurate routine identification method. Many C. striatum strains are multi-drug resistant, being susceptible only to vancomycin and linezolid. We should survey the antimicrobial susceptibility results regularly to monitor its resistance and consider it a possible pathogen.
Bacteremia ; Corynebacterium* ; Disease Outbreaks ; Endocarditis ; Humans ; Linezolid ; Mass Spectrometry ; Methods ; Mucous Membrane ; Skin ; Vancomycin

BACKGROUND: Streptococcus pneumoniae is the most common human pathogen causing community-acquired pneumonia. There is little information on the recent antimicrobial susceptibility patterns of S. pneumoniae in Busan and Gyeongnam of Korea. The aim of this study was to investigate the distribution and antimicrobial resistance of S. pneumoniae at 4 university hospitals in Busan and Gyeongnam. METHODS: We collected and analyzed the antimicrobial susceptibility results of 850 S. pneumoniae strains isolated from regional 4 university hospitals during the last 2 years from July 2013 through June 2015. RESULTS: Among 850 S. pneumoniae strains, 635 strains were isolated from respiratory specimens, followed by blood (N=121), CSF (N=13), and others (N=81). Antimicrobial susceptibility rates to penicillin, cefotaxime and ceftriaxone were 79.4%, 76.6% and 83.6%, respectively. The resistant rates to erythromycin and clindamycin were 80.9% and 68.2%, respectively. The resistant rates to levofloxacin were 9.2%. There were some differences in resistant rates by age groups, years, and specimen types. CONCLUSION: We found the changes of antimicrobial resistance of S. pneumoniae during the last 2 years. It is necessary to monitor the antimicrobial susceptibility of S. pneumoniae regularly for empirical therapy and for early detection of the changes of resistance.
Busan* ; Cefotaxime ; Ceftriaxone ; Clindamycin ; Drug Resistance ; Erythromycin ; Hospitals, University* ; Humans ; Korea ; Levofloxacin ; Penicillins ; Pneumonia ; Streptococcus pneumoniae* ; Streptococcus*

We report a case of an intravascular hemolytic reaction attributable to anti-Jk(b) antibodies that were not detected using an enzyme phase antibody identification test. A 61-year-old male who had received two units of red blood cells was admitted to the emergency room because his urine was dark. LISS/Coombs gel column agglutination tests suggested the presence of anti-Jk(b) and anti-E antibodies. However, his serum was negative for the Jk(b) antigen when an enzyme phase test was performed. A positive reaction was evident, however, when EDTA-treated plasma was tested; this excluded any possible complement-mediated reaction. The patient was diagnosed with an intravascular hemolytic transfusion reaction, caused by anti-Jk(b), and was later discharged without specific complications after receiving antigen-negative blood transfusions.
Agglutination Tests ; Antibodies ; Blood Group Incompatibility* ; Blood Transfusion ; Edetic Acid ; Emergency Service, Hospital ; Erythrocytes ; Humans ; Kidd Blood-Group System ; Male ; Middle Aged ; Plasma

BACKGROUND: Respiratory syncytial virus (RSV) is one of the most important causes of lower respiratory tract infection. The rapid antigen test is a simple, cheap, and quick method for RSV detection, however, it has an acknowledged low sensitivity. The aim of this study is to evaluate the diagnostic performance of the rapid antigen test by comparing it with a multiplex reverse transcription-PCR (RT-PCR). METHODS: A total of 557 nasopharyngeal aspirates or swabs that were submitted for both a rapid antigen test, Binax NOW RSV (Binax; Alere Scarborough, Inc., USA) and multiplex RT-PCR, Seeplex RV7 (Seegene Inc., Korea) were included in this study. We performed both tests according to the manufacturer's recommendations and analyzed the diagnostic performances of a rapid antigen tests based on the results of multiplex RT-PCR. RESULTS: Among the 557 specimens, the positive rates determined from the rapid antigen test and multiplex RT-PCR were 12.2% (N=68) and 25.1% (N=140), respectively. The relative sensitivity and specificity of the rapid antigen test were 46.4% and 99.3% based on the multiplex RT-PCR, respectively. Positive and negative predictive values were 95.6% and 84.7%, respectively. The diagnostic sensitivity was lower (28.6%) in children >36 months compared with children < or =36 months of age. Test sensitivity declined when RSV infection was accompanied by infection with other respiratory viruses. CONCLUSIONS: Binax NOW RSV exhibited good diagnostic performance, easy handling, and rapidity. However, it does have the possibility of false-negative results, and additional tests are needed when there is clinical suspicion of RSV infection.
Child ; Humans ; Respiratory Syncytial Viruses* ; Respiratory Tract Infections ; Sensitivity and Specificity

BACKGROUND: The XN-series (Sysmex, Japan) is the new hematology analyzer from Sysmex, with new channels to improve the accuracy of differential leukocyte count and platelet count in the low cell count range. We evaluated the analytical performance and low white blood cell (WBC) mode of the XN-2000. METHODS: Precision, linearity, and carryover were evaluated for the analyzer. We analyzed the accordance of complete blood count (CBC), reticulocyte count, and differential leukocyte count between the XN-2000 and XE-2100 (Sysmex), using 200 samples from normal controls and patients. For 80 samples with a WBC count <1.5x10(9) cells/L, the low WBC mode was evaluated by comparing the automated count with a manual differential count as the reference. RESULTS: The coefficients of variation of precision were <5% for most CBC parameters and <10% for differential leukocyte count. All results obtained with the XN-2000 showed good correlation with those obtained with the XE-2100. The correlation coefficients (r) were >0.9800 for all CBC parameters except mean corpuscular hemoglobin concentration, mean platelet volume, and platelet distribution width, and >0.9900 for differential leukocyte count except monocytes and basophils. The low WBC mode provided accurate counts for neutrophils and lymphocytes, with r>0.9300 for samples with a WBC count of 0.1-1.5x10(9) cells/L. CONCLUSIONS: The XN-2000 showed good analytical performance and correlation with the existing model, the XE-2100. The XN-2000 provided accurate results for differential leukocyte count in samples with a WBC count of 0.1-1.5x10(9) cells/L, and reduced manual slide reviews.
Basophils ; Blood Cell Count ; Blood Platelets ; Cell Count ; Erythrocyte Indices ; Hematology* ; Humans ; Leukocyte Count* ; Leukocytes ; Lymphocytes ; Mean Platelet Volume ; Monocytes ; Neutrophils ; Platelet Count ; Reticulocyte Count