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Acanthamoeba species are ubiquitous, free-living organisms found in the environment. They can cause a sight-threatening cornea disease, termed Acanthamoeba keratitis, and are often misdiagnosed, causing delayed administration of the correct treatment. Herein, we report a case of Acanthamoeba keratitis diagnosed without culture. A 12-year-old girl with a history of wearing contact lenses presented with complaints of pain, irritation, and hyperemia in the left eye. Corneal scraping-smeared slide, and liquids with contact lenses were submitted to the clinical microbiology laboratory. Cultures of Acanthamoeba spp. were not available; thus, they were stained with calcofluor white. The isolation of Acanthamoeba from the corneal scraping allowed the detection of trophozoites and cysts based on their morphological characteristics. PCR targeting the 18s rRNA gene and subsequent sequencing revealed 99% identity with the Acanthamoeba spp. Although it is challenging to find real-world evidence of Acanthamoeba in clinical microbiology without using culture methods, this case underscores the need for clinical microbiology laboratories to maintain their inspection capabilities.
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Vanrija humicola, a yeast belonging to Trichosporonaceae, is rarely pathogenic. All cases of isolation of V. humicola were retrospectively reviewed from 2021 to 2023. A total of four V. humicola were isolated from urine samples. Organisms cultured for 5 days at 25°C produced yellow, dry and cerebriform colonies, and were successfully identified as V. humicola using Bruker Biotyper MALDI-TOF. Two recent isolates were resistant to fluconazole, echinocandins, and flucytosine. In all 4 cases, V. humicola was sporadically isolated more than 14 days after admission. One case was presumed to be colonized. Of the other three cases that developed a urinary tract infection (UTI), only one with pancytopenia was treated for UTI by V. humicola with caspofungin, but expired 4 days later. V. humicola has emerged as a drug-resistant fungal pathogen of hospital-acquired UTI. Species identification and antifungal susceptibility testing of this organism are required for critical patients.
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A 30-year-old Korean man with myelodysplastic syndrome admitted hospital due to undifferentiated fever and recurrent skin lesions. He received combination therapy with high doses of meropenem, tigecycline and amikacin, yielding carbapenem resistant Klebsiella pneumoniae (CRKP) harboring K. pneumoniae carbapenemase (KPC)-2 from blood cultures on hospital day (HD) 23. Ceftazidime/avibactam was started at HD 37 and CRKP was eradicated from blood cultures after 5 days. However, ceftazidime/avibactam-resistant CRKP carrying KPC-44 emerged after 26 days of ceftazidime/avibactam treatment and then ceftazidime/ avibactam-resistant, carbapenem-susceptible K. pneumoniae carrying KPC-135 was isolated on HD 65. The 3-D homology of KPC protein showed that hot spot changes in the omega loop could be attributed to ceftazidime/avibactam resistance and loss of carbapenem resistance.Whole genome sequencing of serial isolates supported that phenotypic variation was due to clonal evolution than clonal replacement. The treatment regimen was changed from CAZ/AVI to meropenem-based therapy (meropenem 1 g iv q 8 hours and amikacin 600 mg iv per day) starting with HD 72. CAZ/AVI-susceptible CRKP was presented again from blood cultures on HD 84, and the patient expired on HD 85. This is the first Korean report on the acquisition of ceftazidime/avibactam resistance through the emergence of blaKPC variants.
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Background@#Pulmonary nocardiosis is a rare opportunistic infection with occasional systemic dissemination. This study aimed to investigate the computed tomography (CT) findings and prognosis of pulmonary nocardiosis associated with dissemination. @*Methods@#We conducted a retrospective analysis of patients diagnosed with pulmonary nocardiosis between March 2001 and September 2023. We reviewed the chest CT findings and categorized them based on the dominant CT findings as consolidation, nodules and/ or masses, consolidation with multiple nodules, and nodular bronchiectasis. We compared chest CT findings between localized and disseminated pulmonary nocardiosis and identified significant prognostic factors associated with 12-month mortality using multivariate Cox regression analysis. @*Results@#Pulmonary nocardiosis was diagnosed in 75 patients, of whom 14 (18.7%) had dissemination, including involvement of the brain in 9 (64.3%) cases, soft tissue in 3 (21.4%) cases and positive blood cultures in 3 (21.4%) cases. Disseminated pulmonary nocardiosis showed a higher frequency of cavitation (64.3% vs. 32.8%, P = 0.029) and pleural effusion (64.3% vs. 29.5%, P = 0.014) compared to localized infection. The 12-month mortality rate was 25.3%. The presence of dissemination was not a significant prognostic factor (hazard ratio [HR], 0.80; confidence interval [CI], 0.23–2.75; P = 0.724). Malignancy (HR, 9.73; CI, 2.32–40.72; P = 0.002), use of steroid medication (HR, 3.72; CI, 1.33–10.38; P = 0.012), and a CT pattern of consolidation with multiple nodules (HR, 4.99; CI, 1.41–17.70; P = 0.013) were associated with higher mortality rates. @*Conclusion@#Pulmonary nocardiosis with dissemination showed more frequent cavitation and pleural effusion compared to cases without dissemination, but dissemination alone did not affect the mortality rate of pulmonary nocardiosis.
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Background@#This study aimed to evaluate the efficacy of three medical detergents against bacteria and yeast-derived biofilms. @*Methods@#The biofilm removal efficacy of Empower TM (Metrex, USA), Cidezyme TM (Johnson and Johnson Medical Inc, USA), and Matrix mint TM (Whiteley Medical, Australia) were compared to that of chlorine bleach. Biofilms were produced using Staphylococcus aureusRN9120, Escherichia coli ATCC35218, Pseudomonas aeruginosa ATCC27853, Candida albicans ATCC14053, and clinical isolates of Enterococcus faecalis, E. coli, Klebsiella pneumoniae, Candida auris, and Trichosporon asahii. The organisms were suspended in tryptic soy broth (TSB) in 96-well microplates and cultured for 72 hours. They were treated with the detergents, and the residual biofilm mass was quantified using crystal violet staining followed by optical density measurements at 620 nm (OD 620 ). @*Results@#Empower TM and Cidezyme TM significantly reduced the biofilm mass derived from all species by > 50% of OD 620 at 37ºC except those from E. faecalis, T. asahii, and C. auris. Matrix mint TM had no effect on the biofilms under any condition. @*Conclusion@#The culture conditions and the species of the biofilm-producing organism influenced the effectiveness of the detergent. Biofilms produced by E. faecalis, C. auris, and T.asahii were resistant to all detergent treatments under all conditions.
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Human taeniasis is presumed to have almost disappeared from Korea. Recently, we incidentally detected a Taenia saginata infection in an 8-year-old boy undergoing lymphoma diagnosis. The patient had been suffering for 4 months from intensifying snoring and obstructive sleep apnea. A neck computed tomography scan revealed a nasopharyngeal mass, and malignant B-cell lymphoma was supported by punch biopsy. On day 6 of the lymphoma workup period, the patient experienced anal itching, and two proglottids were detected in his stool. The patient had experienced four or five similar episodes within the past 2 years. He self-reported a history of raw beef and fish consumption and no history of traveling abroad. Laboratory findings revealed mild eosinophilia (eosinophil count: 791/μL).Two proglottids exhibited movement and possessed more than 15 branched uterine structures. Long segments approximately 84 cm in length were expelled after praziquantel treatment. Sequencing of the cytochrome oxidase 1 gene confirmed T. saginata, ruling out related Taenia species. After treatment, no proglottids or ova were detected in his stool, and the patient finally started chemotherapy for lymphoma. This case highlights the importance of timely diagnosis of hidden taeniasis in low-frequency endemic regions.
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Background@#Blood culture (BC) systems have evolved to increase sensitivity and reduce turnaround times. This study compared the performance of a 4-day versus a 5-day BC incubation period using the BD BACTEC™ FX (Becton, Dickinson and Company, USA). @*Methods@#A total of 37,379 consecutive sets of BC were evaluated over a 3-month period in a 2,700-bed tertiary care hospital. Positive BC results were reviewed to assess time-to-positivity (TTP) and species identification of the isolates. The BCs were performed in pairs of vials, utilizing either BD BACTEC Plus Aerobic/F or Peds Plus/F with BD BACTEC Lytic Anaerobic media. @*Results@#A total of 14,899 episodes, averaging 2.51 sets per episode, were analyzed. Of these, 1,398 (9.38%) were positive, yielding 1,465 isolates. TTP (hours) were 96 in 1.64%. The two most prevalent organisms, Escherichia coli and Klebsiella spp. were detected within 12 hours in 88.75% and 78.90%, respectively. The respective median TTP (T50) values for E. coli, Klebsiella spp., Enterococcus faecalis/E. faecium, and Staphylococcus aureus were 9.24, 9.60, 13.75, and 14.20. T50 values for these species were significantly shorter in anaerobic bottles than in aerobic bottles. Of 24 BCs with TTP > 96, only 4 containing anaerobic bacteria or molds were first detected after 96 hours. @*Conclusion@#A 4-day incubation has demonstrated excellent sensitivity. However, a 5-day incubation may be beneficial for hospitals caring for patients at high risk for infections with slow-growing fungi or fastidious bacteria.
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The sensitivity of the (1–3)-β-D-glucan (BDG) diagnostic test for candidemia varies in different clinical settings, and its usefulness in early diagnosis of candidemia is suboptimal. We evaluated the sensitivity of the test for early candidemia prediction. All adult patients with culture-proven candidemia who underwent a serum Goldstream Fungus (1–3)-β-D-Glucan Test within seven days prior to candidemia onset at a tertiary referral hospital between January 2017 and May 2021 were included. Any-positive BDG results within seven days prior to candidemia onset were obtained in 38 out of 93 (40.9%) patients. The positive rate increased when the test was performed near the day of candidemia onset (P=0.04) but reached only 52% on the day of candidemia onset. We observed no significant differences between BDG-positive and -negative groups in terms of underlying disease, risk factors for candidemia, clinical presentation, origin of candidemia, and 30-day mortality. Candida albicans was significantly associated with positive BDG results than with all-negative BDG results (P=0.04). The Goldstream BDG test is unreliable for candidemia prediction because of its low sensitivity. Negative BDG results in patients with a high risk of invasive candidiasis should be interpreted with caution.
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While the coronavirus disease 2019 pandemic is ongoing, monkeypox has been rapidly spreading in non-endemic countries since May 2022. Accurate and rapid laboratory tests are essential for identifying and controlling monkeypox. Korean Society for Laboratory Medicine and the Korea Disease Prevention and Control Agency have proposed guidelines for diagnosing monkeypox in clinical laboratories in Korea. These guidelines cover the type of tests, selection of specimens, collection of specimens, diagnostic methods, interpretation of test results, and biosafety. Molecular tests are recommended as confirmatory tests. Skin lesion specimens are recommended for testing in the symptomatic stage, and the collection of both blood and oropharyngeal swabs is recommended in the presymptomatic or prodromal stage.
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Background@#The concurrent detection of human cytomegalovirus (CMV) with UL97 and UL54 mutations is crucial for prescribing adequate antiviral treatment when drug-resistant CMV infection is suspected. We investigated the frequency of resistance-conferring mutations among patients with persistent or recurrent CMV infection and further reviewed the subgroup with UL54 mutations without UL97 mutations. @*Methods@#Patients with persistent or recurrent CMV infection after 4 weeks of treatment with ganciclovir or foscarnet were consecutively enrolled between November 2012 and May 2019.The direct sequencing of UL97 and UL54 was performed to detect resistance mutations in CMV. @*Results@#A total of 101 sequencing datasets were obtained from 65 enrolled patients.CMV UL97 and UL54 mutations were detected in 15.4% (10/65) and 9% (6/65) of patients, respectively. The CMV retrieved from two patients (3%) had mutations in both genes. Four patients with CMV UL54 mutations alone had a history of haploidentical peripheral blood stem cell transplantation, and foscarnet was administered for over 4 weeks to these patients; 21.5% of patients had suspected resistant CMV infection with either UL97 or UL54 mutations. @*Conclusion@#In this study, CMV UL54 mutations but not UL97 mutations were found in patients subjected to prolonged foscarnet administration for CMV disease.
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Background@#Bacterial infections are well known factors underlying acute exacerbations in bronchiectasis. However, viral infections may also contribute to acute exacerbations. We aimed to assess the rate of viral detection in acute exacerbations of bronchiectasis, and the associated clinical factors. @*Methods@#Diagnostic tests for viral and bacterial etiologies were performed in 792 patients with bronchiectasis who visited the emergency room or the respiratory care inpatient unit in a tertiary referral center in South Korea. All patients were diagnosed with bronchiectasis by chest computerized tomography and were prescribed antibiotics for a minimum of 3 days. @*Results@#Viral pathogens were detected in 202 of the 792 enrolled patients (25.5%). The most common viral pathogen isolated was influenza A virus (24.8%), followed by rhinovirus (22.4%), influenza B virus (9.8%), respiratory syncytial virus B (8.9%), and human metapneumovirus (6.1%). In 145 patients, a viral, but not bacterial, pathogen was detected, whereas no pathogens were found in 443 patients with exacerbations. Multivariable analysis revealed that female sex and chronic heart disease as a comorbidity were positively associated with viral detection in acute exacerbations of patients with bronchiectasis, whereas the presence of radiographic infiltration was negatively associated. @*Conclusion@#Respiratory viruses were identified in approximately 25% of the acute exacerbations observed among patients with bronchiectasis. Of the viruses detected, influenza viruses and rhinovirus made up over 50%. More attention to viruses as possible causative pathogens for acute deteriorating symptoms in patients with bronchiectasis is warranted.
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Background@#HLA-DQ typing in deceased donors is not mandatory in Korea. Therefore, when patients develop DQ antibodies after kidney transplantation (KT) from deceased donor, it is impossible to determine whether they are donor-specific antibodies (DSA). We developed DQ prediction programs for the HLA gene and evaluated their clinical utility. @*Methods@#Two HLA-DQ prediction programs were developed: one based on Lewontin’s linkage disequilibrium (LD) and haplotype frequency and the other on an artificial neural network (ANN). Low-resolution HLA-A, -B, -DR, and -DQ typing data of 5,603 Korean patients were analyzed in terms of haplotype frequency and used to develop an ANN DQ prediction program. Predicted DQ (pDQ) genotype accuracy was analyzed using the typed DQ data of 403 patients. pDQ DSA agreement, sensitivity, specificity, and false-negative rate was evaluated using 1,970 single-antigen bead assays performed on 885 KT recipients. The clinical significance of DQ and pDQ DSA was evaluated in 411 KT recipients. @*Results@#pDQ genotype accuracies were 75.4% (LD algorithm) and 75.7% (ANN). When the second most likely pDQ (LD algorithm) was also considered, the genotype accuracy increased to 92.6%. pDQ DSA (LD algorithm) agreement, sensitivity, specificity, and falsenegative rate were 97.5%, 97.3%, 98.6%, and 2.4%, respectively. The antibody-mediated rejection treatment frequency was significantly higher in DQ or pDQ DSA-positive patients than in DQ or pDQ DSA-negative patients (P < 0.001). @*Conclusions@#Our DQ prediction programs showed good accuracy and could aid DQ DSA detection in patients who had undergone deceased donor KT without donor HLA-DQ typing.
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Background@#Coronavirus disease 2019 (COVID-19) outbreaks emerged at two universityaffiliated hospitals in Seoul (hospital A) and Uijeongbu City (hospital S) in the metropolitan Seoul area in March 2020. The aim of this study was to investigate epidemiological links between the outbreaks using whole genome sequencing (WGS) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). @*Methods@#Fifteen patients were enrolled in the study, including four non-outbreak (A1–A4) and three outbreak cases (A5–A7) in hospital A and eight cases (S1–S8) in hospital S. Patients' hospital stays, COVID-19 symptoms, and transfer history were reviewed. RNA samples were submitted for WGS and genome-wide single nucleotide variants and phylogenetic relationships were analyzed. @*Results@#The index patient (A5) in hospital A was transferred from hospital S on 26 March.Patients A6 and A7 were the family caregiver and sister, respectively, of the patient who shared a room with A5 for 4 days. Prior to transfer, A5 was at the next bed to S8 in the emergency room on 25 March. Patient S6, a professional caregiver, took care of the patient in the room next to S8's room for 5 days until 22 March and then S5 for another 3 days.WGS revealed that SARS-CoV-2 in A2, A3, and A4 belong to clades V/B.2, S/A, and G/B.1, respectively, whereas that of A5–A7 and S1-S5 are of the V/B.2.1 clade and closely clustered. In particular, SARS-CoV-2 in patients A5 and S5 showed perfect identity. @*Conclusion@#WGS is a useful tool to understand epidemiology of SARS-CoV-2. It is the first study to elucidate the role of patient transfer and caregivers as links of nosocomial outbreaks of COVID-19 in multiple hospitals.
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Background@#Rapid detection of carbapenemase-producing Enterobacterales (CPE) is desirable to guide antimicrobial therapy and infection control. The NG-Test Carba5 (Carba5;NG Biotech, France) rapid multiplex lateral flow immunoassay and BD MAX Check-Points CPO Assay (CPO; BD Diagnostic Systems, USA) fully automated real-time PCR assay were evaluated for the detection of KPC, NDM, VIM, IMP, and OXA-48-like group in a culture colony compared to genotyping using conventional PCR. @*Methods@#Among the clinical isolates of carbapenem-resistant Enterobacterales (CRE) collected from 2013 to 2019, up to 20 isolates for each carbapenemase type, and approximately 60 carbapenemase-negative CRE were enrolled. Genotyping of carbapenemases were performed using single-target PCR for KPC, NDM, and OXA-48-like group and the multiplex PCR for VIM, IMP, GIM, SIM, and SPM. All isolates were tested with Carba5 and CPO. The discrepant results were resolved by single-target specific conventional PCR or GeneXpert Carba-R Assay (Carba-R; Cepheid, USA). @*Results@#Of 147 CREs, 82 were CPE (55.8%) including 20 KPC, 22 NDM, 17 VIM, three IMP, and 13 OXA-48-like group, and seven double carbapenemase-positive (three KPC/VIM, two NDM/ VIM, one KPC/NDM, and one NDM/OXA-48-like group) isolates. Carba5 and CPO detected all CPE correctly along with two more IMP-producing CPE. The sensitivity and specificity of both kits were equally 100% and 97%. Two false IMP-positives were confirmed IMP-positive with Carba-R and IMP-specific single-target PCR. @*Conclusion@#Carba5 and CPO reliably detect and differentiate five common carbapenemases in cultured colonies. Carba5, faster and simpler, is preferred as a spot test.
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Background@#Rapid detection of carbapenemase-producing Enterobacterales (CPE) is desirable to guide antimicrobial therapy and infection control. The NG-Test Carba5 (Carba5;NG Biotech, France) rapid multiplex lateral flow immunoassay and BD MAX Check-Points CPO Assay (CPO; BD Diagnostic Systems, USA) fully automated real-time PCR assay were evaluated for the detection of KPC, NDM, VIM, IMP, and OXA-48-like group in a culture colony compared to genotyping using conventional PCR. @*Methods@#Among the clinical isolates of carbapenem-resistant Enterobacterales (CRE) collected from 2013 to 2019, up to 20 isolates for each carbapenemase type, and approximately 60 carbapenemase-negative CRE were enrolled. Genotyping of carbapenemases were performed using single-target PCR for KPC, NDM, and OXA-48-like group and the multiplex PCR for VIM, IMP, GIM, SIM, and SPM. All isolates were tested with Carba5 and CPO. The discrepant results were resolved by single-target specific conventional PCR or GeneXpert Carba-R Assay (Carba-R; Cepheid, USA). @*Results@#Of 147 CREs, 82 were CPE (55.8%) including 20 KPC, 22 NDM, 17 VIM, three IMP, and 13 OXA-48-like group, and seven double carbapenemase-positive (three KPC/VIM, two NDM/ VIM, one KPC/NDM, and one NDM/OXA-48-like group) isolates. Carba5 and CPO detected all CPE correctly along with two more IMP-producing CPE. The sensitivity and specificity of both kits were equally 100% and 97%. Two false IMP-positives were confirmed IMP-positive with Carba-R and IMP-specific single-target PCR. @*Conclusion@#Carba5 and CPO reliably detect and differentiate five common carbapenemases in cultured colonies. Carba5, faster and simpler, is preferred as a spot test.
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Background@#Bacterial infections are well known factors underlying acute exacerbations in bronchiectasis. However, viral infections may also contribute to acute exacerbations. We aimed to assess the rate of viral detection in acute exacerbations of bronchiectasis, and the associated clinical factors. @*Methods@#Diagnostic tests for viral and bacterial etiologies were performed in 792 patients with bronchiectasis who visited the emergency room or the respiratory care inpatient unit in a tertiary referral center in South Korea. All patients were diagnosed with bronchiectasis by chest computerized tomography and were prescribed antibiotics for a minimum of 3 days. @*Results@#Viral pathogens were detected in 202 of the 792 enrolled patients (25.5%). The most common viral pathogen isolated was influenza A virus (24.8%), followed by rhinovirus (22.4%), influenza B virus (9.8%), respiratory syncytial virus B (8.9%), and human metapneumovirus (6.1%). In 145 patients, a viral, but not bacterial, pathogen was detected, whereas no pathogens were found in 443 patients with exacerbations. Multivariable analysis revealed that female sex and chronic heart disease as a comorbidity were positively associated with viral detection in acute exacerbations of patients with bronchiectasis, whereas the presence of radiographic infiltration was negatively associated. @*Conclusion@#Respiratory viruses were identified in approximately 25% of the acute exacerbations observed among patients with bronchiectasis. Of the viruses detected, influenza viruses and rhinovirus made up over 50%. More attention to viruses as possible causative pathogens for acute deteriorating symptoms in patients with bronchiectasis is warranted.
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Background/Aims@#We evaluated the usefulness in kidney transplant (KT) candidates of cytomegalovirus (CMV)-specific enzyme-linked immunospot (ELISPOT) assays for predicting the development of post-transplant CMV infections. @*Methods@#All adult recipients admitted for living-donor KT between March 2014 and March 2015 were prospectively enrolled except donor CMV-seropositive and recipient seronegative (D+/R–) recipients. All the enrolled patients underwent CMV-specific ELISPOT assays before transplant, and a researcher blinded to the results of these assays examined the patients for CMV infection at least 6 months post-transplant. @*Results@#Of 133 KT recipients, 44 (33%) developed CMV infections. When we used the cut-off determined by receiver operator characteristic curve, 16 of the 34 patients (47%) with negative pp65-specific ELISPOT results (< 11 spots/200,000 cells) developed CMV infections, whereas 28 of the 99 patients (39%) with positive pp65-specific ELISPOT results at baseline (≥ 11 spots/200,000 cells) developed CMV infections after KT (p = 0.02). Based on the multivariable Cox regression model, negative pp65-specific ELISPOT assay results was an independent risk factor for CMV infection (adjusted hazard ratio [AHR], 1.87; 95% confidence interval [CI], 1.01 to 3.46; p = 0.047) as well as age (AHR, 1.05; 95% CI, 1.01 to 1.08; p = 0.007). @*Conclusions@#Pre-transplant CMV-specific ELISPOT assay appears to predict the development of CMV infections after KT in recipients at moderate risk such as CMV-seropositive recipients (Clinical Trial Registration Number NCT 02025335).
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Background@#Inconclusive SARS-CoV-2 real-time reverse transcription-PCR (rRT-PCR) test results, which are positive for one or more target genes but not all, are problematic in clinical laboratories. In this study, we aimed to investigate the cause and clinical relevance of such inconclusive results. @*Methods@#rRT-PCR was performed using the Allplex 2019-nCoV assay kit (Seegene Inc., Korea) targeting the following three genes: E, RdRp, and N. For all inconclusive test results reported from March to June 2020, the frequency per kit, lot number, specimen type, cycle threshold (Ct) and peak values of the amplification curves, positive target genes, and results of repeated or consecutive tests were analyzed. @*Results@#A total of 43,268 tests were conducted, of which 93 (0.21%) were inconclusive—49 from 11 coronavirus disease 2019 (COVID-19) patients and 44 from non-COVID-19 patients.In COVID-19 patients, the results were inconclusive 11.9 ± 4.7 days after diagnosis and were negative 8.8 ± 5.5 days after the inconclusive results were reported. However, in nonCOVID-19 patients, they were all negative upon retest and 81.8% of them were identified to have yielded in 2 out of 8 lots. The most frequently positive target genes were N (55.4%) in COVID-19 and RdRp (61.2%) in non-COVID-19 patients, respectively. No difference was observed in the Ct or peak values of the amplification curves for inconclusive samples between COVID-19 and non-COVID-19 cases. @*Conclusion@#Inconclusive test results should be reported neither positive nor negative. Such results can be reported as inconclusive without retesting in COVID-19 patients; however, they should certainly be confirmed by a retest in non-COVID-19 patients or newly diagnosed cases.
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This study investigated resistance mechanisms and epidemiology of emerging linezolid-nonsusceptible Enterococcus faecalis (LNSEF) in a tertiary care hospital. LNSEF isolated from clinical samples were collected from November 2017 to June 2019. The isolates were investigated for linezolid resistance and the associated molecular mechanisms, including mutations of 23S rRNA domain V and acquisition of the cfr or optrA resistance gene. We used pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing for the molecular typing of the isolates. Among 4,318 E. faecalis isolates, 10 (0.23%) were linezolid-nonsusceptible. All LNSEF isolates were optrA-positive and cfr-negative. Of these isolates, five were sequence type (ST) 476, two ST585, one ST16, one ST16-like, and one ST480. Six LNSEF isolates obtained in the first year clustered to three types in the PFGE analysis: two ST476 isolates of type A, two ST585 isolates of type B, and two ST16 or ST16-like isolates of type C. Seven cases were of community-onset and three were hospital acquired, but total of eight were healthcare-associated including five community-onset. None of the patients had a history of linezolid treatment, and in one patient, we detected linezolid-susceptible E. faecalis one month before LNSEF detection. In conclusion, heterogenous clones of optrA-positive LNSEF emerged in the hospital mainly via community-onset.
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The outbreak of coronavirus disease 2019 (COVID-19), which began in December 2019, is still ongoing in Korea, with >9,000 confirmed cases as of March 25, 2020. COVID-19 is a severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) infection, and real-time reverse transcription-PCR is currently the most reliable diagnostic method for COVID-19 around the world. Korean Society for Laboratory Medicine and the Korea Centers for Disease Prevention and Control propose guidelines for diagnosing COVID-19 in clinical laboratories in Korea. These guidelines are based on other related domestic and international guidelines, as well as expert opinions and include the selection of test subjects, selection of specimens, diagnostic methods, interpretation of test results, and biosafety.