Objective: Open surgical wound is prone to surgical site infection due to contamination of surrounding environment. Therefore, routine air sampling and culture of two operating rooms (OR) was performed from 2018 to 2023 to monitor and evaluate air quality and provide appropriate infection control measures. Method: 2 OR regularly performing prosthetic insertion were selected for routine air sampling every 6 months due to high risk of surgical infection associated with the procedure. Air sampling was performed by collecting 1000 litre of air over 10 minutes using air sampler (MAS-100 Eco, Merck). Collected air was cultured on blood agar plate and Sabourand dextrose agar for 30 days, and pathogen identification and quantification was performed upon positive culture result. This study employed a cut-off point of 17.6 colony forming unit (CFU) as specified by federal standards on biological particles published by National Aeronautics and Space Administration. Results: 12 air samplings was performed from 2018 to 2023. A single case of positive bacterial air culture was reported (20 CFU, coagulase-negative Staphylococcus). Infection control measures were provided upon reporting of positive bacterial air culture, including inspection of positive pressure ventilation system and high efficiency particulate air filter, disinfection of OR and the equipment, and more strict regulation of temperature and humidity. Air sampling was repeated after imposing the measures to evaluate their effectiveness. Cases of surgical site infection caused by the identified pathogen were monitored for 90 days, after which it was determined that there was no surgical site infection related to positive air culture. Conclusion: The six-year monitoring of OR air sampling confirmed that detection of positive air culture in routine sampling was not associated with surgical site infection. Based on this result, the hospital decided to conduct air sampling and culture only in outbreak of surgical site infection as part of epidemiologic evaluation.

Prototheca wickerhamii is an achlorophyllic algae that rarely acts as an opportunistic pathogen in humans. We report the case of a 66-year-old female patient with a history of diabetes mellitus who presented with a pus-like discharge from face, facial redness, and swelling. The patient was admitted to the emergency room with worsening facial pain. Gram staining from pus-like discharge revealed yeast like features; however, an isolated colony on a blood agar plate was not identified using VITEK 2 (Biomerieux) or matrix-assisted laser desorption/ionization time-of flight mass spectrometry (MALDI-TOF) using VITEK®MS (Biomerieux). Lactophenol cotton blue staining of the colony revealed characteristic sporangia and endospore features. After performing the protein extraction procedure for filamentous fungi (mold) isolates using ethanol and formic acid, MALDI-TOF MS identified the colony as Prototheca wickerhamii, with 99.9% confidence. This case indicates that Prototheca spp. require specialized sample preparation steps, such as the ethanol/formic acid extraction procedure, for identification using MALDI-TOF MS.

This study retrospectively reviewed the microbiological and clinical characteristics of patients diagnosed with bacteremia. Results from the first positive blood cultures were consecutively collected from July 2022 to June 2023 at a public secondary hospital, a university-affiliated tertiary hospital, and a university-affiliated secondary hospital in the Seoul metropolitan area. Antibiotic spectrum coverage (ASC) scores were calculated on the day the blood culture was performed (B0) and on two days after the blood culture results were reported (R+2). A total of 3,397 isolates were collected from 3,094 patients. Among these, 949 isolates obtained from 893 patients were classified as multidrug-resistant organisms (MDRO), including 170 imipenem-resistant gram-negative bacteria, 714 methicillin-resistant staphylococci, and 65 vancomycin-resistant enterococci. Interestingly, 13 and 42 gram-positive isolates were resistant to linezolid and quinupristin/dalfopristin, respectively. Moreover, 44 and 181 gram-negative isolates were resistant to amikacin and tigecycline, respectively. The proportion of ASC scores corresponding to broad or extremely broad-spectrum coverage was not significantly different between MDRO and non-MDRO groups at B0 (p = 0.0925). However, it increased in the MDRO group at R+2 (p <0.001). This study found that resistance to last-resort antimicrobials is emerging. Therefore, developing and incorporating molecular diagnostics using a wide range of resistance targets may facilitate rapid, tailored antimicrobial treatments.

Acquired fluconazole resistance (FR) in bloodstream infection (BSI) isolates of Candida albicans is rare. We investigated the FR mechanisms and clinical features of 14 fluconazole non-susceptible (FNS; FR and fluconazole-susceptible dose-dependent) BSI isolates of C. albicans recovered from Korean multicenter surveillance studies during 2006- 2021. Mutations causing amino acid substitutions (AASs) in the drug-target gene ERG11 and the FR-associated transcription factor genes TAC1, MRR1, and UPC2 of the 14 FNS isolates were compared with those of 12 fluconazole-susceptible isolates. Of the 14 FNS isolates, eight and seven had Erg11p (K143R, F145L, or G464S) and Tac1p (T225A, R673L, A736T, or A736V) AASs, respectively, which were previously described in FR isolates. Novel Erg11p, Tac1p, and Mrr1p AASs were observed in two, four, and one FNS isolates, respectively. Combined Erg11p and Tac1p AASs were observed in seven FNS isolates. None of the FR-associated Upc2p AASs were detected. Of the 14 patients, only one had previous azole exposure, and the 30-day mortality rate was 57.1% (8/14). Our data show that Erg11p and Tac1p AASs are likely to contribute to FR in C. albicans BSI isolates in Korea and that most FNS C. albicans BSIs develop without azole exposure.

Background: Rapid detection of the causative agents is essential for determining the appropriate treatment for patients with lower respiratory tract infections. We evaluated the performance of the Biofire FilmArray pneumonia panel (FA-PE; BioFire Diagnostics, USA) in the identification of bacterial pathogens and antibiotic resistance genes in endotracheal aspirate specimens. Methods: A total of 43 non-duplicated endotracheal aspirates were included in this study. The performance of the FA-PE was assessed using the routine culture method as the reference standard. Results: The FA-PE demonstrated 92.9% sensitivity and 79.3% specificity for the identification of 15 bacterial targets compared to routine bacterial culture. Four antimicrobial resistance genes in 43 specimens were detected by the FA-PE. The most frequently detected resistance genes were mecA/C and SCCmec in three specimens, followed by CTX-M in one specimen. Conclusion: The FA-PE offers a rapid diagnostic method for lower respiratory tract infections. It may be useful at the early stage of pneumonia, before routine culture and antimicrobial susceptibility results are available.

BACKGROUND:Campylobacter spp., common commensals in the gastrointestinal tract of animals, especially poultry, can cause acute gastrointestinal illness in humans through animal-to-human transmission. Although Campylobacter fetus, especially subspecies fetus, rarely leads to systemic infections such as bacteremia in immunocompromised patients, it is unclear whether Campylobacter fetus subspecies venerealis (Cfv) causes infectious diseases in humans.CASE PRESENTATION:A 28-year-old man with a history of chronic alcoholism visited the emergency department with weakness of the left extremities. The patient was clinically diagnosed with community-acquired bacterial meningitis. The organism from the blood culture was subsequently identified as Campylobacter fetus. On phylogenetic analysis, the 16S rRNA sequence showed 99.93% similarity with other Cfv 16S rRNA sequences. The patient had no exposure to identifiable sources except for close contact with a companion dog, which could have been a possible source of transmission.CONCLUSIONS:This case suggests that Cfv could lead to human systemic infections such as meningitis and that companion animals, in addition to well-known animal hosts, could be sources of transmission.

We investigated the clinical outcomes and molecular mechanisms of fluconazole-resistant (FR) Candida glabrata bloodstream infections. Among 1,158 isolates collected during multicenter studies in South Korea during 2008–2018, 5.7% were FR. For 64 patients with FR bloodstream infection isolates, the 30-day mortality rate was 60.9% and the 90-day mortality rate 78.2%; these rates were significantly higher than in patients with fluconazole-susceptible dose-dependent isolates (30-day mortality rate 36.4%, 90-day mortality rate 43.8%; p<0.05). For patients with FR isolates, appropriate antifungal therapy was the only independent protective factor associated with 30-day (hazard ratio 0.304) and 90-day (hazard ratio 0.310) mortality. Sequencing of pleiotropic drug-resistance transcription factor revealed that 1–2 additional Pdr1p amino acid substitutions (except genotype-specific Pdr1p amino acid substitutions) occurred in 98.5% of FR isolates but in only 0.9% of fluconazole-susceptible dose-dependent isolates. These results highlight the high mortality rate of patients infected with FR C. glabrata BSI isolates harboring Pdr1p mutations.

a Department of Laboratory Medicine, University of Ulsan College of Medicine and Asan Medical Center, Seoul, Republic of Korea b Korea Centers for Disease Control and Prevention, Chungcheongbuk-do, Republic of Korea c Department of Laboratory Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea d Department of Laboratory Medicine, Ajou University School of Medicine, Suwon, Republic of Korea

External quality assessment (EQA) is essential for ensuring reliable test results, especially when laboratories are using assays authorized for emergency use for newly emerging pathogens. We developed an EQA panel to assess the quality of real-time reverse transcription PCR assays being used in South Korea to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). With the participation of 23 public health organization laboratories and 95 nongovernmental laboratories involved in SARS-CoV-2 testing, we conducted qualitative and semiquantitative performance assessments by using pooled respiratory samples containing different viral loads of SARS-CoV-2 or human coronavirus OC43. A total of 110 (93.2%) laboratories reported correct results for all qualitative tests; 29 (24.6%) laboratories had >1 outliers according to cycle threshold values. Our EQA panel identified the potential weaknesses of currently available commercial reagent kits. The methodology we used can provide practical experience for those planning to conduct evaluations for testing of SARS-CoV-2 and other emerging pathogens in the future.

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/ by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Background: Liquid biopsy is a useful assay for the diagnosis, treatment, and prognosis prediction of solid tumors and its clinical application is expanding. Therefore, the need for developing an External Quality Assessment (EQA) protocol for liquid biopsy is increasing. In this study, we developed and implemented the liquid biopsy EQA program for the epidermal growth factor receptor mutation. Methods: We validated the feasibility of the protocol using citrate instead of ethylenediaminetetraacetic acid (EDTA). Additionally, we analyzed the homogeneity and stability of the aliquoted quality control (QC) materials. Mutation-positive QC material with four mutations (exon 19 deletion, L858R, T790M, and exon 20 insertion) was used to make two types of QC materials (low and high) and the wild type material was used for the negative controls. If the EQA results showed consensus in more than 80% of the participating laboratories, the results were reported as acceptable or unacceptable. If not, we reported the results as not graded. Results: Citrate showed equivalent performance to EDTA. Highly mutated QC material and mutation-negative QC material passed the homogeneity and stability test, but low-level mutant specimens showed inconsistent results. In total, 11 laboratories participated, and all of them reported consistent results except for low-grade mutant samples. Thus, the evaluation results were acceptable except for low mutation QC material. Conclusions: The applicability of liquid biopsy is expanding. To obtain accurate test results, EQA is indispensable. Here, QC materials for liquid biopsy EQA were produced, distributed, and had its results analyzed. This study could be the foundation for further development of liquid biopsy EQA. (Lab Med Qual Assur 2020;42:91-96)

BACKGROUND:Without standardization of medical laboratory's testing practices, there is an increase in false diagnoses when relying on test results. However, the effect of test standardization is difficult to assess numerically. This study's purpose is to quantify the effect of the standardization level of a laboratory on the prevalence of diabetes mellitus (DM) and impaired fasting glucose (IFG).METHODS:Laboratories were classified into three levels: 'highly-standardized laboratory,' 'basically-standardized laboratory,' and 'non-standardized laboratory.' Based on the results of Korean External Quality Assessment Scheme (KEQAS), the cutoff values for diagnosis of DM and IFG were recalculated, given false positive and false negative rates.RESULTS:The prevalence of DM and IFG in the population as a whole was estimated using the 2013 Korea National Health and Nutrition Examination Survey (KNHANES) database. When the prevalence of DM from KNHANES was 11.88% (95% confidence interval [CI], 10.59%-13.17%), the proportion with a systematic false error ranged from 10.91% (95% CI, 9.65%-12.17%) to 13.09% (95% CI, 11.74%-14.45%). The prevalence of IFG varied from 13.59% (95% CI, 12.25%-14.91%) to 40.49% (95% CI, 38.54%-42.43%), in contrast to 24.58% (95% CI, 22.85%-26.31%) of the reference value. The prevalence of DM and IFG tended to be over- and under-estimated more as the laboratory standardization level became lower, respectively.CONCLUSION:Our study proved that standardization of clinical laboratory tests is an important factor affecting the prevalence estimation of national disease statistics based on the simulation using KNHANES data.

Candida glabrata bloodstream infection (BSI) isolates from a particular geographic area have been reported to comprise a relatively small number of the major sequence types (STs) by multilocus sequence typing (MLST) analysis. Yet little is known about the characteristics of major ST strains of C. glabrata. To address this question in Korea, we investigated antifungal resistance and non-synonymous mutations of the mismatch repair gene (msh2 mutations) in C. glabrata BSI isolates, as well as associated clinical characteristics, and compared the results according to MLST genotype. We assessed a total of 209 C. glabrata BSI isolates from seven hospitals in Korea for 2 years (2009 and 2014). Clinical features of candidemia and their outcomes were analyzed for 185 available cases. According to MLST, ST7 (47.8%) was the most common type, followed by ST3 (22.5%); the remainder represented 28 types of minor STs (29.7%). Fluconazole-resistance (FR) rates for ST7, ST3, and other strains were 9.0% (9/100), 8.5% (4/47), and 4.8% (3/62), respectively, and all were susceptible to amphotericin B and micafungin. All ST7 isolates harbored the V239L mutation in msh2, known to confer hypermutability, while 91.5% of ST3 isolates did not harbor the msh2 mutation. Overall, isolates of the same ST had identical msh2 mutations, with the exception of nine isolates. The msh2 mutations were identified in 68.8% (11/16) of the FR isolates and 67.4% (130/193) of the fluconazole susceptible-dose dependent isolates. There was no significant difference in all clinical characteristics between ST3 and ST7. However, the 30-day mortality of C. glabrata candidemia due to the two major ST (ST3 or ST7) strains was significantly higher than that of candidemia due to other minor ST strains (45.1 vs. 25.0%, p < 0.05). Multivariate logistic regression analysis also showed that two major STs (ST3 and ST7) were independent predictors of 30-day mortality. This study showed for the first time that two STs (ST7 and ST3) were predominant among BSI isolates in Korea, and that C. glabrata BSI isolates belonging to two major MLST genotypes are characterized by higher mortality. In addition, most msh2 mutations align with MLST genotype, irrespective of FR.

Background Multilocus sequence typing (MLST) is useful in determining the long-term evolutionary process and minimizes differences in experimental results across individuals and laboratories. It is also useful in determining evolutionary origins and backgrounds of bacterial species. This study carries out MLST analysis on VanA-type vancomycin-resistant Enterococcus faecium isolated from patient specimens in a single university hospital over nine years in order to observe changes in genetic evolution over time. Methods During the years from 2007 to 2015, 44 clinical isolates of vanA-containing E. faecium were collected from Ajou University Hospital in Korea. Species were identified by the VitekII system (bio-Merieux, USA), and antibiotic susceptibility testing was performed by disk diffusion and E-test according to Clinical and Laboratory Standards Institute (CLSI) guidelines. To determine genetic relatedness, matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF M/S) was employed. To characterize clonal diversity, MLST analysis was used. Results All isolates were highly resistant to ampicillin, ciprofloxacin, and vancomycin but showed variable levels of resistance to teicoplanin. The 44 clinical isolates were genetically unrelated according to MALDI-TOF M/S analysis. MLST showed that the clinical isolates harbored 6 sequence types (ST), with ST17 (n=19) being the most common, followed by ST78 (n=13), ST192 (n=6), ST64 (n=4), ST262 (n=1), and ST414 (n=1). Conclusion The MLST analysis showed that the sequence types of most isolates belonged to clonal complex 17 This is consistent with outbreaks in hospitals. We had single observations for ST262 and ST414, suggesting that they were random occurrences. MLST can be useful for speculating the genetic evolution of VanA-containing E. faecium isolates.

We investigated the in vitro antifungal susceptibilities of cryptic Aspergillus species from nine Korean hospitals. Based on the CLSI epidemiological cutoff values, resistance rates to amphotericin B, itraconazole, voriconazole, posaconazole and caspofungin were as follows: A. awamori (34 isolates; all 0%), A. tubingensis (22; 0%, 4.5%, 0%, 0%, and 0%, respectively), A. sydowii (16; 0%, 6.3%, 0%, 0%, and 6.3%), A. lentulus (2; 50%, 0%, 100%, 50%, and 0%), and A. tamarii (2; all 0%). A. calidoustus (one isolate) showed resistance to multiple drugs. Thus, cryptic species identification can be mandatory for clinically important Aspergillus isolates, with their susceptibility data.

ABSTRACT We investigated the azole resistance mechanisms and clinical features of fluconazole-nonsusceptible (FNS) isolates of Candida tropicalis recovered from Korean surveillance cultures in comparison with fluconazole-less-susceptible (FLS) isolates. Thirty-five clinical isolates of C. tropicalis , comprising 9 FNS (fluconazole MIC, 4 to 64 μg/ml), 12 FLS (MIC, 1 to 2 μg/ml), and 14 control (MIC, 0.125 to 0.5 μg/ml) isolates, were assessed. CDR1 , MDR1 , and ERG11 expression was quantified, and the ERG11 and UPC2 genes were sequenced. Clinical features of 16 patients with FNS or FLS bloodstream isolates were analyzed. Both FNS and FLS isolates had >10-fold higher mean expression levels of CDR1 , MDR1 , and ERG11 genes than control isolates ( P values of <0.02 for all). When FNS and FLS isolates were compared, FNS isolates had 3.4-fold higher mean ERG11 expression levels than FLS isolates ( P = 0.004), but there were no differences in those of CDR1 or MDR1 . Of all 35 isolates, 4 (2 FNS and 2 FLS) and 28 (8 FNS, 11 FLS, and 9 control) isolates exhibited amino acid substitutions in Erg11p and Upc2p, respectively. Both FNS and FLS bloodstream isolates were associated with azole therapeutic failure (3/4 versus 4/7) or uncleared fungemia (4/6 versus 4/10), but FNS isolates were identified more frequently from patients with previous azole exposure (6/6 versus 3/10; P = 0.011) and immunosuppression (6/6 versus 3/10; P = 0.011). These results reveal that the majority of FNS C. tropicalis isolates show overexpression of CDR1 , MDR1 , and ERG11 genes, and fungemia develops after azole exposure in patients with immunosuppression.

TO THE EDITOR: The International Randomized Interferon versus STI-571 study was the first randomized trial to demonstrate the prognostic significance of monitoring BCR-ABL1 transcripts by real-time quantitative polymerase chain reaction (RT-PCR) [1], and defined a major molecular response (MMR) after treatment as a 3-log10 reduction from the baseline value in the level of measured BCR-ABL1 transcripts [1]. On the other hand, an international scale (IS) was proposed as an absolute value of 0.1% BCR-ABL1, which corresponds to a 3-log10 reduction from the baseline value, for MMR, in an effort made by international experts to standardize BCR-ABL1 quantification [2,3].

Background Vancomycin-resistant Enterococci (VRE) infections are caused by Enterococcus faecium in about 90% of the cases but can also be caused by Enterococcus faecalis. Thus, this study investigates factors that cause a low isolation rate of vancomy-cin-resistant E. faecalis (VREfs). To this end, the au-thors study the clinical traits, resistant gene structure, genomic classification, and molecular characteristics of the virulent factor. Methods From January 2001 through September 2011, 17 vanA-containing E. faecalis isolates were collected from hospitalized patients at Ajou University Hospital in Korea. Identification, antimicrobial susceptibility testing, and PCR of van and esp genes were performed. Pulsed-field gel electrophoresis (PFGE) was used for strain typing. PCR and sequencing of the internal regions of Tn1546 were performed for structural analysis of the van gene. Results Of 4,235 VRE infections, 3,918 (92.5%) were caused by E. faecium, and 95 (2.2%) were caused by E. faecalis. In 67% of VREfs infections, there was a preceding occurrence of E. faecium infection. All isolates were of genotype vanA. Our isolates were div-ided into three types according to the distribution of IS elements integrated into Tn1546 (types I to IIb). The PFGE results showed no clonal relatedness among isolates. Conclusion Our study found that VREfs infections af-fect patients who have experienced vancomycin-re-sistant E. faecium. (VREfm) infection or undergo in-vasive procedures. The VREfs seems to involve the horizontal transfer of Tn1546 transposon from VREfm.

We applied the new clinical breakpoints (CBPs) of the Clinical and Laboratory Standards Institute (CLSI) to a multicenter study to determine the antifungal susceptibility of bloodstream infection (BSI) isolates of Candida species in Korea, and determined the relationship between the frequency of antifungal-resistant Candida BSI isolates and antifungal use at hospitals. Four hundred and fifty BSI isolates of Candida species were collected over a 1-year period in 2011 from nine hospitals. The susceptibilities of the isolates to four antifungal agents were determined using the CLSI M27 broth microdilution method. By applying the species-specific CBPs, non-susceptibility to fluconazole was found in 16.4% (70/428) of isolates, comprising 2.6% resistant and 13.8% susceptible-dose dependent isolates. However, non-susceptibility to voriconazole, caspofungin, or micafungin was found in 0% (0/370), 0% (0/437), or 0.5% (2/437) of the Candida BSI isolates, respectively. Of the 450 isolates, 72 (16.0%) showed decreased susceptibility to fluconazole [minimum inhibitory concentration (MIC) ≥4 μg/ml]. The total usage of systemic antifungals varied considerably among the hospitals, ranging from 190.0 to 7.7 defined daily dose per 1,000 patient days, and fluconazole was the most commonly prescribed agent (46.3%). By Spearman's correlation analysis, fluconazole usage did not show a significant correlation with the percentage of fluconazole resistant isolates at hospitals. However, fluconazole usage was significantly correlated with the percentage of fluconazole non-susceptible isolates (r = 0.733; P = 0.025) or the percentage of isolates with decreased susceptibility to fluconazole (MIC ≥4 μg/ml) (r = 0.700; P = 0.036) at hospitals. Our work represents the first South Korean multicenter study demonstrating an association between antifungal use and antifungal resistance among BSI isolates of Candida at hospitals using the new CBPs of the CLSI.

BACKGROUND:Standard protocols are lacking for the preparation of platelet lysates (PL) as an alternative to using fetal bovine serum as a cell culture supplement. This study aimed to establish optimum conditions for preparing PL for use in cell cultures.METHODS:Cell density in three pooled platelet concentrates (PC) were adjusted to 1×10(12)/L and 2×10(12)/L. PL was prepared from PC by 1 to 3 freeze-thaw (FT) cycles. HaCaT cells were cultured in media supplemented with 5% or 10% PL. Cell numbers were estimated using a Cell Counting Kit-8 (CCK-8; Dojindo Laboratories, Japan). Growth factors were quantified by using the Luminex 200 system (Luminex Corporation, USA).RESULTS:Cell proliferation rates in the presence of PLs were similar when prepared from PCs of both cell densities. The rates were higher in media containing 5% PL than 10% PL when prepared by two FT cycles. Concentrations of vascular endothelial growth factor (VEGF), platelet-derived growth factor-AB/BB (PDGF-AB/BB), PDGF-AA, and epidermal growth factor (EGF) were significantly higher in PL prepared from PC with a cell density of 2×10(12)/L than 1×10(12)/L PC. However, only VEGF and PDGF-AA concentrations in PLs were correlated with HaCaT cell counts.CONCLUSIONS:The 5% PL from PC with a cell density of 1×10(12)/L prepared by two FT cycles treatment was the most effective condition that supported steady HaCaT cell proliferation. Our finding may be useful for preparing PL-supplemented cell culture media.