Clinical usefulness of anaerobic blood culture in pediatric patients with bacteremia.

OBJECTIVES: The purpose of this study is to evaluate the usefulness of anaerobic blood culture in pediatric patients by comparing the detection rate and distribution of bacteria between aerobic and anaerobic blood culture bottles. METHODS: A retrospective analysis was conducted on 11,664 blood cultures obtained from children under the age of 14 between January 2013 and June 2020. The positive rate of total, aerobic, and anaerobic blood culture, as well as the species distribution of each blood culture bottle, were investigated. RESULTS: The positive rate of blood culture was 2.4 % (N = 281). Among them, 67 (23.8 %), 85 (30.3 %) and 129 (45.9 %) organisms were grown in only aerobic, only anaerobic, and both blood culture bottles, respectively. Gram-positive cocci were cultured on both, only aerobic, and only anaerobic blood culture bottles in proportions of 46.4 %, 23.4 %, and 30.2 %, respectively. Gram-negative bacilli were cultured on both, only aerobic, and only anaerobic blood culture bottles in proportions of 58.5 %, 12,3 %, and 29.2 %, respectively. Gram-positive bacilli grew best in aerobic bottle only. There were seven strains of obligate anaerobes. CONCLUSION: Because many facultative anaerobic bacteria are recognized primarily from anaerobic blood culture bottles, combining aerobic and anaerobic blood culture bottles might be beneficial in pediatric patients with suspected blood stream infection.

Serotype Distribution and Antimicrobial Resistance of Streptococcus pneumoniae Causing Invasive Pneumococcal Disease in Korea Between 2017 and 2019 After Introduction of the 13-Valent Pneumococcal Conjugate Vaccine.

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.

Clinical Usefulness of BACT Count and BACT-Info Flag of UF-5000 for Screening for Urinary Tract Infection and Prediction of Gram-Negative Bacteria.

BACKGROUND: A rapid and reliable screening test for urinary tract infection (UTI) is needed to reduce the turn-around time and to rule out negative results of urine culture. The aim of this study was to evaluate the performance of BACT count and BACT-Info flag of the UF-5000 for screening for UTI. METHODS: A total of 1,063 urine specimens from April to September 2019 were included in this study. We evaluated the diagnostic performance of white blood cell (WBC) count, BACT count, BACT-Info flag, and UTI flag in UF-5000 by comparing with the urine culture results. RESULTS: Of the urine specimens, 16.7% were culture-positive (≥ 105 CFU/mL) with 15 being yeast positive. A BACT count of > 685.3/µL showed the best diagnostic performance with 93.8% sensitivity and 90.2% specificity. We confirmed that the combination of BACT count (685.3/µL) and BACT-Info flag would be appropriate to use in a clinical laboratory (sensitivity 91.5%, specificity 90.5%). Based on this combination, the sensitivity and specificity of the Gram-negative flag were 95.5% and 94.8%. CONCLUSIONS: We recommend the use of a combination of BACT count (685.3/µL) and BACT-Info for UTI diagnosis. This combination is more appropriate for Gram-negative bacteria, and it would be useful for selecting empirical treatment.

Performance of BD MAX Group B Streptococcus (GBS) Assay without Enrichment for the Detection of GBS.

Group B streptococcus (GBS) is an important pathogen causing neonatal early-onset disease. We evaluated the diagnostic performance of BD Max GBS assay (Becton Dickinson, Franklin Lakes, NJ, USA) without enrichment (direct BDM) for detecting GBS using vaginal and rectal specimens in comparison with culture. In total, 716 specimens collected from 358 pregnant women between June 2018 and May 2020 were included in this study. Bacterial culture was performed using ChromID Strep B agar (bioMérieux, Marcy-l'Étoile, France), and species identification results were confirmed using the VITEK-MS system (bioMérieux). The sensitivity of direct BDM for vaginal and rectal specimens was 75.0% and 100%, respectively. Thirteen specimens showed discrepant results: 10 false-negative results in the vaginal specimens and three false-positive results in the rectal specimens. The overall agreement between direct BDM and culture was 98.9% (354/358). The final sensitivity and specificity of direct BDM were 98.5% and 99.0%, respectively. Discrepant results-one false-negative and three false-positives-were obtained for four specimens. Direct BDM shows a good diagnostic performance and will be useful for GBS screening within a few hours.

Serotype Distribution and Antimicrobial Resistance of Salmonella Isolates in Korea between 2016 and 2017.

Salmonella is one of the major causes of food-borne infections. We investigated the serotype distribution and antimicrobial resistance of Salmonella isolates collected in Korea between January 2016 and December 2017. In total, 669 Salmonella isolates were collected from clinical specimens at 19 university hospitals. Serotyping was performed according to the Kauffmann-White scheme, and antimicrobial susceptibility was tested using Sensititre EUVSEC plates or disk diffusion. Among the strains, C (39.8%) and B (36.6%) were the most prevalent serogroups. In total, 51 serotypes were identified, and common serotypes were S. enterica serovar I 4,[5],12:i:- (16.7%), S. Enteritidis (16.1%), S. Bareilly (14.6%), S. Typhimurium (9.9%), and S. Infantis (6.9%). The resistance rates to ampicillin, chloramphenicol, and trimethoprim-sulfamethoxazole were 32.6%, 12.1%, and 8.4%, respectively. The resistance rates to cefotaxime and ciprofloxacin were 8.1% and 3.0%, respectively, while 5.4% were multidrug-resistant. S. enterica serovar I 4,[5],12:i:- and S. Enteritidis were highly prevalent, and there was an increase in rare serotypes. Multidrug resistance and ciprofloxacin resistance were highly prevalent. Periodic investigations of Salmonella serotypes and antimicrobial resistance are needed.

Serotype Distribution and Antimicrobial Resistance of Invasive and Noninvasive Streptococcus pneumoniae Isolates in Korea between 2014 and 2016.

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.

Evaluation of the Cobas u 701 microscopy analyser compared with urine culture in screening for urinary tract infection.

Purpose. A new automated Cobas u 701 microscopy analyser for urine sediment examination was introduced. The aim of this study was to evaluate the analyser in comparison with urine culture in screening for urinary tract infection (UTI).Methodology. A total of 852 urine specimens submitted for culture were included in this study. Urine sediment examination was performed using the Cobas u 701 microscopy analyser. The results of the bacteria (BAC) and yeast (YEA) analyses were compared with the results from urine culture as a method for UTI screening. In addition, we compared the BAC results with white blood cells (WBCs) and leukocyte and nitrite measurement in the Cobas u 601 system.Results. Of the 852 urine specimens, 16.1 % (N=137) were positive by urine culture, yielding 130 bacteria from 124 specimens and 14 yeasts from 14 specimens. The Cobas u 701 microscopy analyser provided no result for 52 specimens because of their high turbidity. The sensitivity, specificity, positive predictive value and negative predictive value were 85.8, 69.4, 33.1 and 96.5 %, respectively. For YEA, these figures were 100, 91.9, 15.8 and 100 %, respectively. The areas under the curve for BAC and WBCs were 0.827 [95 % confidence interval (CI) 0.799, 0.852] and 0.727 (95 % CI 0.695, 0.757), respectively. The sensitivity of the leukocyte and nitrite was 63.5 and 54.6 %, respectively.Conclusion. The Cobas u 701 microscopy analyser showed good diagnostic performance. It can be used for rapid screening for UTI and can reduce the number of cultures required.

Outbreak of KPC-2-producing Enterobacteriaceae caused by clonal dissemination of Klebsiella pneumoniae ST307 carrying an IncX3-type plasmid harboring a truncated Tn4401a.

Over a 5-month period between the end of June and the beginning of November in 2015, a KPC-producing Enterobacteriaceae outbreak occurred in a general hospital in Busan, South Korea, being associated with a total of 50 clinical isolates from 47 patients. Multilocus sequence typing and pulsed-field gel electrophoresis were carried out for strain typing and whole-genome sequencing was performed to characterize the plasmids. A clonal spread of K. pneumoniae sequence type 307 (ST307) carrying a self-transferable IncX3-type plasmid harboring blaKPC-2 was responsible for the outbreak. Sporadic emergence of K. pneumoniae ST697 carrying an IncFII-type plasmid and a ST11 isolate harboring a small plasmid devoid of any known origin of replication were observed to be associated with blaKPC-3, but no further dissemination of these strains was identified. The results indicated a healthcare-associated infection associated with a blaKPC-harboring plasmid dissemination and a clonal spread of KPC-producing Enterobacteriaceae.

Serotype Distribution and Antimicrobial Resistance of Streptococcus pneumoniae Isolates Causing Invasive and Noninvasive Pneumococcal Diseases in Korea from 2008 to 2014.

Introduction. Streptococcus pneumoniae is an important pathogen with high morbidity and mortality rates. The aim of this study was to evaluate the distribution of common serotypes and antimicrobial susceptibility of S. pneumoniae in Korea. Methods. A total of 378 pneumococcal isolates were collected from 2008 through 2014. We analyzed the serotype and antimicrobial susceptibility for both invasive and noninvasive isolates. Results. Over the 7 years, 3 (13.5%), 35 (10.8%), 19A (9.0%), 19F (6.6%), 6A (6.1%), and 34 (5.6%) were common serotypes/serogroups. The vaccine coverage rates of PCV7, PCV10, PCV13, and PPSV23 were 21.4%, 23.3%, 51.9%, and 62.4% in all periods. The proportions of serotypes 19A and 19F decreased and nonvaccine serotypes increased between 2008 and 2010 and 2011 and 2014. Of 378 S. pneumoniae isolates, 131 (34.7%) were multidrug resistant (MDR) and serotypes 19A and 19F were predominant. The resistance rate to levofloxacin was significantly increased (7.2%). Conclusion. We found changes of pneumococcal serotype and antimicrobial susceptibility during the 7 years after introduction of the first pneumococcal vaccine. It is important to continuously monitor pneumococcal serotypes and their susceptibilities.

MALDI-TOF MS is more accurate than VITEK II ANC card and API Rapid ID 32 A system for the identification of Clostridium species.

All 50 Clostridium difficile strains were definitely identified by Vitek2 system, Rapid ID 32A system, and MALDI-TOF. For 18 non-difficile Clostridium strains, the identification results were correct in 2, 0, and 17 strains by Vitek2, Rapid ID 32A, and MALDI-TOF, respectively [corrected].

Sirolimus for Refractory Autoimmune Hemolytic Anemia after Allogeneic Hematopoietic Stem Cell Transplantation: A Case Report and Literature Review of the Treatment of Post-Transplant Autoimmune Hemolytic Anemia.

Autoimmune hemolytic anemia (AIHA) may occur after any type of allogeneic hematopoietic stem cell transplantation (HCT), even ABO-matched transplantation. It tends to be refractory to standard corticosteroid treatment and requires multiple transfusions. Though, there is no consensus regarding the optimal treatment for post-transplant severe AIHA. We present a pediatric patient with refractory AIHA after umbilical cord blood transplantation. She developed severe AIHA at 3months after transplantation and was unresponsive to multiple treatment modalities, including corticosteroids, intravenous immunoglobulin, plasma exchange and rituximab, resulting in persistent transfusion dependency. Sirolimus, a mammalian target of rapamycin inhibitor, was started on day 67 after the onset of AIHA, and this patient was successfully rescued without any complications. Sirolimus induces apoptosis in autoreactive lymphocytes, increases regulatory T cells and has been reported to have a positive effect on AIHA following solid organ transplantation (SOT). We reviewed the literature regarding post-transplant AIHA in the PubMed database and evaluated the treatment outcome of sirolimus in AIHA after SOT.

Serial changes in serum procalcitonin, interleukin 6, and C-reactive protein levels according to non-specific surgical stimulation.

BACKGROUND: The aim of this study is to investigate useful perioperative monitoring markers by comparing serial levels of serum procalcitonin (PCT), interleukin 6 (IL-6), and C-reactive protein (CRP) in routine surgical circumstances. METHODS: In 285 surgeries of 277 patients, blood samples were obtained serially, at least three times per patient: within 48 h before surgery, 0-6 h after surgery (post-OP1), >6-28 h after surgery (post-OP2), and/or later (post-OP3). PCT, IL-6, and CRP were measured. Their demographic, operative, laboratory, and clinical data were collected retrospectively. RESULTS: The systemic inflammatory response syndrome (SIRS) (n=39) and sepsis (n=11) groups showed higher post-operative values than the non-SIRS group (n=233). Their maximum significant median levels were 8.96 vs. 0.21 µg/L for post-OP2 PCT, 743.1 vs. 85.8 ng/L for post-OP1 IL-6, and 103.4 vs. 49.0 mg/L for post-OP2 CRP. Among non-SIRS patients, 12 patients developed undesirable post-operative events, including secondary surgery and death. The highest area under receiver operator characteristic curves was 0.92 at post-OP1 PCT (cut-off, 0.1 µg/L; sensitivity, 91.7%; specificity, 78.7%), and the next highest was 0.84 at post-OP1 IL-6 (cut-off, 359 ng/L; sensitivity, 66.7%; specificity, 91.9%). All biomarkers were increased by non-specific surgical stimuli; however, post-OP1/post-OP2 PCT were <1.0 µg/L (90th percentile) except major abdominal surgeries. CONCLUSIONS: Post-OP1 PCT measurement may be useful as a post-operative monitoring marker for the following reasons: pre-operative values less than the cut-off regardless of pre-operative state (age, malignancy, and American Society of Anesthesiologists class); minimal influence from surgical stimulus; and prediction of post-operative undesirable events.

Misidentification of Candida guilliermondii as C. famata among strains isolated from blood cultures by the VITEK 2 system.

Introduction. The aim of this study was to differentiate between Candida famata and Candida guilliermondii correctly by using matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) and gene sequencing. Methods. Twenty-eight Candida strains from blood cultures that had been identified as C. famata (N = 25), C. famata/C. guilliermondii (N = 2), and C. guilliermondii (N = 1) by the VITEK 2 system using the YST ID card were included. We identified these strains by MALDI-TOF MS and gene sequencing using the 28S rRNA and ITS genes and compared the results with those obtained by the VITEK 2 system. Results. All 28 isolates were finally identified as C. guilliermondii. Sequencing analysis of the 28S rRNA gene showed 99.80%-100% similarity with C. guilliermondii for all 28 strains. The ITS gene sequencing of the strains showed 98.34%-100% homology with C. guilliermondii. By MALDI-TOF, we could correctly identify 21 (75%) of 28 C. guilliermondii isolates. Conclusion. We should suspect misidentification when C. famata is reported by the VITEK 2 system, and we always should keep in mind the possibility of misidentification of any organism when an uncommon species is reported.

Evaluation of DNA extraction methods and their clinical application for direct detection of causative bacteria in continuous ambulatory peritoneal dialysis culture fluids from patients with peritonitis by using broad-range PCR.

BACKGROUND: The aims of this study were to compare several DNA extraction methods and 16S rDNA primers and to evaluate the clinical utility of broad-range PCR in continuous ambulatory peritoneal dialysis (CAPD) culture fluids. METHODS: Six type strains were used as model organisms in dilutions from 10(8) to 10(0) colony-forming units (CFU)/mL for the evaluation of 5 DNA extraction methods and 5 PCR primer pairs. Broad-range PCR was applied to 100 CAPD culture fluids, and the results were compared with conventional culture results. RESULTS: There were some differences between the various DNA extraction methods and primer sets with regard to the detection limits. The InstaGene Matrix (Bio-Rad Laboratories, USA) and Exgene Clinic SV kits (GeneAll Biotechnology Co. Ltd, Korea) seem to have higher sensitivities than the others. The results of broad-range PCR were concordant with the results from culture in 97% of all cases (97/100). Two culture-positive cases that were broad-range PCR-negative were identified as Candida albicans, and 1 PCR-positive but culture-negative sample was identified as Bacillus circulans by sequencing. Two samples among 54 broad-range PCR-positive products could not be sequenced. CONCLUSIONS: There were differences in the analytical sensitivity of various DNA extraction methods and primers for broad-range PCR. The broad-range PCR assay can be used to detect bacterial pathogens in CAPD culture fluid as a supplement to culture methods.