We assessed the performance of the VITEK 2 AST-N439 card for susceptibility testing of novel β-lactam/β-lactamase inhibitor (BL/BLI) combinations and colistin in carbapenem-non-susceptible gram-negative isolates. A total of 425 clinical isolates, including Enterobacterales (n = 242), Pseudomonas aeruginosa (n = 97), and Acinetobacter baumannii (n = 86), were tested using VITEK 2, with broth microdilution as the reference standard. Minimum inhibitory concentrations were interpreted according to Clinical and Laboratory Standards Institute breakpoints. The essential agreement (EA), categorical agreement (CA), very major error rate, and major error rate for VITEK 2 were 90.3%, 97.6%, 1.8%, and 2.5% for ceftazidime/avibactam; 81.5%, 89.0%, 7.0%, and 4.7% for ceftolozane/tazobactam; 96.5%, 90.9%, 3.4%, and 1.2% for imipenem/relebactam; and 94.6%, 93.0%, 15.8%, and 3.2% for meropenem/vaborbactam. For colistin, VITEK 2 demonstrated an EA of 89.2% and a CA of 85.4%. Our findings suggest that VITEK 2 has suboptimal performance for novel BL/BLI combinations in carbapenem-non-susceptible gram-negative isolates. Furthermore, despite changes to the colistin formulation used in the VITEK 2 card, it remains an unreliable method for detecting colistin resistance. IMPORTANCE:Rapid and accurate antimicrobial susceptibility testing (AST) is essential for managing infections caused by multidrug-resistant gram-negative bacilli. This study evaluated the performance of the VITEK 2 AST-N439 card for susceptibility testing of novel BL/BLI combinations and colistin in carbapenem-non-susceptible gram-negative isolates. Our findings revealed significant limitations, including suboptimal performance for novel BL/BLI combinations and unreliable detection of colistin resistance, even with the updated formulation. These results underscore the need for cautious interpretation of VITEK 2 results and highlight the importance of optimizing its performance to enhance antibiotic decision-making.

Current guidelines recommend a two-step algorithm rather than relying solely on a single test for diagnosing Clostridioides difficile infection. This algorithm starts with enzyme immunoassay (EIA) for detecting glutamate dehydrogenase (GDH) and toxins A/B, followed by nucleic acid amplification test (NAAT) for GDH-positive but toxin-negative cases. This study compared the performance of three commercial NAATs: the STANDARD M10 C. difficile, Xpert C. difficile, and BD MAX Cdiff assays, utilized as confirmatory testing of the two-step algorithm. Two hundred archived stool specimens, previously tested GDH-positive but toxin-negative by EIA, were analyzed in parallel with these NAATs and toxigenic culture, which served as the reference standard. Sensitivity, specificity, positive predictive value, and negative predictive value were 89.1%, 92.6%, 94.6%, and 85.2%, respectively, for the M10 assay; 95.8%, 86.4%, 91.2%, and 93.3%, respectively, for the Xpert assay; and 89.8%, 91.4%, 93.8%, and 86.0%, respectively, for the BD MAX assay. The rates of invalid results were 1.0%, 0.5%, and 1.0% for the M10, Xpert, and BD MAX assays, respectively. In conclusion, the M10 assay is a reliable diagnostic tool, performing comparably to the Xpert and BD MAX assays when used as confirmatory testing in the two-step algorithm.IMPORTANCEWhile numerous studies have assessed nucleic acid amplification tests (NAATs) as stand-alone tests for diagnosing Clostridioides difficile infection, limited research has compared their performance as confirmatory tests in a two-step algorithm. This study evaluated the performance of three commercial NAATs (M10, Xpert, and BD MAX assays) using 200 archived stool specimens initially tested as glutamate dehydrogenase (GDH)-positive but toxin-negative by GDH/toxin A/B enzyme immunoassay, the first step in the two-step algorithm. All three assays demonstrated high sensitivity (89.1% to 95.8%) and specificity (86.4% to 92.6%), with low rates of invalid results (≤1%). Our findings suggest that the M10 assay performs comparably to the Xpert and BD MAX assays when used as confirmatory testing in the two-step algorithm. Offering similar performance and turnaround time to these widely used assays at a slightly lower cost, the M10 assay serves as a practical alternative in this setting.

Accurate and rapid diagnostic assays that simultaneously detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and influenza A/B are crucial for effective clinical management and infection control. In the present study, we evaluated the cobas SARS-CoV-2 & Influenza A/B v2 assay (Roche Diagnostics, Basel, Switzerland) using the Roche cobas 5800 system, comparing it to the Allplex SARS-CoV-2/FluA/FluB/RSV assay (Seegene, Seoul, Republic of Korea). A total of 871 nasopharyngeal swab specimens, including 164 SARS-CoV-2-positive, 76 influenza A-positive, 77 influenza B-positive, and 554 negative specimens, were tested using the cobas and Allplex assays in parallel. The positive percent agreement and negative percent agreement between the cobas and Allplex assays were 100% and 98.3% for SARS-CoV-2, 100% and 99.1% for influenza A, and 100% and 99.3% for influenza B, respectively. Cohen's kappa values ranged from 0.95 to 0.96, indicating almost perfect agreement. The limits of detection for SARS-CoV-2 E and open reading frame 1ab genes, influenza A, and influenza B were 25.3, 12.4, 16.1, and 11.0 copies/mL, respectively. No cross-reactivity was observed with 29 non-target respiratory pathogens. These findings demonstrate that the cobas assay reliably detects SARS-CoV-2 and influenza A/B with high sensitivity and specificity. Notably, this assay enables high-throughput automated workflows, facilitating timely decision-making during SARS-CoV-2 and influenza cocirculation.IMPORTANCEAccurate and rapid diagnostic assays that simultaneously detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and influenza A/B are essential for effective clinical management and infection control. This study demonstrates that the cobas SARS-CoV-2 & Influenza A/B v2 assay reliably detects SARS-CoV-2 and influenza A/B with high sensitivity and specificity. Designed for use on the cobas 5800/6800/8800 systems, this assay supports high-throughput automated workflows, enabling timely decision-making during periods of high testing demand, such as the cocirculation of SARS-CoV-2 and influenza.

Background:The Xpert MTB/RIF Ultra (Xpert Ultra) was introduced to enhance the sensitivity of tuberculosis detection, particularly in smear-negative cases, compared with its predecessor, Xpert MTB/RIF (Xpert). However, its performance in high-resource, intermediate-burden settings remains unassessed. We prospectively compared the diagnostic accuracy of Xpert Ultra and Xpert for detecting Mycobacterium tuberculosis (MTB) and rifampin resistance in Korea. Methods:In total, 309 respiratory specimens were analyzed using both assays. We used two reference standards: mycobacterial culture and a composite reference standard based on clinical diagnosis and treatment decisions. Diagnostic performance, including sensitivity, specificity, and agreement between the two assays, was assessed. Spiking experiments using 13 MTB isolates with known rpoB mutations were performed to evaluate rifampin resistance detection. Results:Xpert Ultra showed increased, albeit not significantly, sensitivity (73.7% vs. 65.8% with culture; 63.8% vs. 53.2% with the composite reference standard) over Xpert. Its specificity was comparable to that of Xpert; however, a few false-positive results were observed among trace- and very low-positives. Among six culture-negative but Xpert Ultra-positive cases, two were clinically diagnosed as tuberculosis. Of the 13 rpoB mutant strains, Xpert correctly detected all mutations in the rifampin resistance-determining region, whereas Xpert Ultra yielded indeterminate results for Q432P and Q429H/L430P/H445Q. Conclusions:Xpert Ultra tends to have increased sensitivity; however, it shows potential diagnostic ambiguity associated with trace- or very low-positive results. These findings highlight the importance of clinical correlation, particularly in culture-negative cases. Indeterminate results in certain rpoB mutations require cautious interpretation.

The clinical relevance and drug resistance patterns of nontuberculous mycobacteria (NTM) vary by species. This study investigated the species distribution of NTM isolated from respiratory specimens at a tertiary care hospital in South Korea from 2017 to 2022. A retrospective analysis was conducted on laboratory data from respiratory specimens submitted for acid-fast bacilli culture. NTM isolates were identified using a line probe assay, and those unidentifiable at the species or complex level underwent multigene sequencing of the 16S rRNA, rpoB, and hsp65 genes. Among all mycobacterial isolates, the proportion of NTM showed an increasing trend, rising from 87.4% in 2017 to 93.3% in 2022. The eight most common species were M. avium complex (61.9%), M. abscessus (14.2%), M. fortuitum complex (8.4%), M. gordonae (5.3%), M. simiae complex (3.4%), M. kansasii complex (1.9%), M. terrae complex (1.5%), and M. chelonae (1.2%), accounting for 97.7% of all NTM isolates. Among the remaining isolates (2.3%, n = 169), 161 were classified into 24 species and groups, the majority with proportions below 0.1%. Two of the eight isolates that could not be identified at the species or group level despite multigene sequencing underwent whole-genome sequencing, which suggested they likely represent novel Mycobacterium species. This study provides valuable insights into the distribution of NTM species, particularly rarely encountered species, isolated from respiratory specimens in South Korea. These findings may aid in optimizing diagnostic strategies and selecting appropriate treatment options.IMPORTANCEGiven the significant variations in clinical relevance and drug resistance patterns among nontuberculous mycobacteria (NTM) species, understanding their geographic distribution is essential for selecting appropriate treatment options and improving patient outcomes. This study investigated the distribution of NTM species isolated from respiratory specimens at a tertiary care hospital in South Korea from 2017 to 2022. Our findings revealed an increasing proportion of NTM, with M. avium complex and M. abscessus remaining predominant. Additionally, we identified 24 rarely encountered species and groups, along with two strains that likely represent novel Mycobacterium species. Our study advances the understanding of the evolving NTM epidemiology in South Korea, contributing to the optimization of diagnostic strategies and improvement of patient management.

Microbiological diagnosis of pleural infection is often hindered by the low sensitivity of conventional culture. The automated blood culture system (ABCS) has been shown to improve diagnostic sensitivity for the culture of non-blood specimens. This study examined the additional diagnostic benefit of ABCS against conventional bacterial culture in patients who underwent thoracentesis or percutaneous drainage. Non-duplicate patients whose pleural fluid samples were tested using both conventional culture and ABCS (BACT/ALERT 3D and VIRTUO, bioMerieux) from 2001 through 2021 were included. Cases were excluded if only contaminants such as coagulase-negative staphylococci, Corynebacterium species, and Bacillus species were identified. Data on culture results, demographics, and laboratory tests were collected. Of the 9,020 patients, 632 patients had positive results in ABCS after excluding those considered contaminants (n = 180) or those positive only in conventional culture (n = 5). Conventional culture was positive in 302 (47.8%) patients, whereas 330 (52.2%) patients had isolates only from ABCS. Patients with positive results from ABCS alone had lower pleural fluid lactate dehydrogenase and serum C-reactive protein (CRP) and higher pleural fluid glucose and protein. Among organisms isolated from ABCS alone, viridans group streptococci, Staphylococcus aureus, and Klebsiella spp. were the most common organisms identified. Higher pleural fluid glucose and blood white blood cells and lower CRP were significant factors associated with exclusive ABCS positivity. More than half of the patients whose pleural fluid cultures were positive using ABCS had a negative result on conventional culture. Our results suggest that ABCS might enhance the microbiologic diagnosis of pleural infection.IMPORTANCEThis study demonstrated that an automated blood culture system (ABCS) has superior sensitivity in pleural infections compared with conventional culture. By comparing both methods in over 9,000 patients, researchers found that ABCS detected bacteria in approximately twice as many cases as conventional culture, especially in patients with a high probability of pleural infection. The findings suggest that ABCS can be a valuable tool in improving the accuracy of diagnosing pleural infections, which could lead to better treatment decisions and patient outcomes.

Background: Group B Streptococcus (GBS) is one of the leading causes of neonatal early-onset sepsis, resulting in high mortality and significant comorbidity. Intrapartum penicillin prophylaxis is recommended for pregnant women with GBS colonization to prevent vertical transmission. For pregnant women at high risk of anaphylaxis to penicillin, clindamycin is recommended only if the susceptibility of GBS isolates has been identified. We retrospectively examined the GBS detection rate and clindamycin resistance among Korean women of reproductive age over the last 20 years. Methods: Microbiologic studies using vaginal, vaginal-rectal or vaginal-perianal swabs from female patients 15-49 years of age during 2003-2022 were reviewed. Annual GBS detection rates and clindamycin resistance rates were calculated. The study period was divided into two periods (period 1, 2003-2015; period 2, 2016-2022) based on the introduction of universal culture-based GBS screening in our center in 2016. GBS detection rates and clindamycin resistance rates were compared between the periods using chi(2) tests. Results: A total of 14,571 women were tested 16,879 times and GBS was isolated in 1,054 tests (6.2%), with 423 clindamycin-resistant isolates (40.1%). The GBS detection rate increased from 3.4% (301/8,869) in period 1 to 9.4% (2,753/8,010) in period 2 (P < 0.001). Even during period 1, the GBS detection rate was higher in 2009-2015 compared to 2003-2008 (P < 0.001). Clindamycin resistance rates have remained at similar levels since 2009, which were 39.5% (199/301) in period 1 and 40.2% (303/753) in period 2 (P = 0.833). Conclusion: This study demonstrated that GBS detection rates in Korean women of reproductive age significantly increased almost three times during the twenty years of the study period, with a persistently high clindamycin resistance rate of up to 40%.

High concentration of mold spores in inhaled air is an important risk factor for invasive mold infections. COVID‐19 (coronavirus disease 2019)‐associated pulmonary aspergillosis (CAPA) is a serious complication of severe COVID‐19. To investigate the mold distribution in negative‐pressure isolation wards and its potential association with CAPA incidence, we conducted microbiological air sampling and retrospectively analyzed CAPA cases in a tertiary care hospital in Korea during the COVID‐19 pandemic. Air sampling was conducted in January 2022 at multiple sites in four negative‐pressure isolation wards designated for managing severe COVID‐19 patients. A portable microbial air sampler (MAS‐100 NT) was used for air sampling, and Tryptic Soy Agar plates were incubated to identify mold isolates at the genus level. CAPA cases (January 2021–June 2023) were defined by antifungal treatment, mycological evidence (serum galactomannan index > 0.5), and radiological findings. Immunomodulator use, including dexamethasone and tocilizumab, was analyzed to identify clinical risk factors influencing CAPA incidence. Among the isolated molds, Aspergillus (86.7%) was the most prevalent, followed by Penicillium (53.3%), Mucorales (20%), and Paecilomyces (13.3%). Mold concentrations were highest in areas adjacent to a construction site. Intervention procedures, including installing air purifiers and reinforcing seals between the adjoining construction site and isolation ward, effectively reduced mold concentrations and paralleled a decline in CAPA incidence. While increased foot traffic after the relaxation of COVID‐19 restriction measures led to a rise in spore concentration, the incidence of CAPA did not increase, likely due to the decreased use of immunomodulators such as corticosteroids and tocilizumab. Construction‐related mold spore increases can be mitigated with appropriate interventions, and pedestrian traffic near isolation wards may need regulation. Monitoring and mitigating environmental mold contamination are crucial to preventing opportunistic respiratory mold infections in negative‐pressure isolation wards and should be interpreted in conjunction with clinical risk factors.

Background Rapid antimicrobial susceptibility testing (AST) for bloodstream infections (BSIs) facilitates the optimization of antimicrobial therapy, preventing antimicrobial resistance and improving patient outcomes. QMAC-dRAST (QuantaMatrix Inc., Korea) is a rapid AST platform based on microfluidic chip technology that performs AST directly using positive blood culture broth (PBCB). This study evaluated the performance of QMAC-dRAST for Gram-negative bacteria using PBCB and subcultured colony isolates, comparing it with that of VITEK 2 (bioM & eacute;rieux, France) using broth microdilution (BMD) as the reference method. Methods We included 141 Gram-negative blood culture isolates from patients with BSI and 12 carbapenemase-producing clinical isolates of Enterobacterales spiked into blood culture bottles. QMAC-dRAST performance was evaluated using PBCB and colony isolates, whereas VITEK 2 and BMD were tested only on colony isolates. Results For PBCB, QMAC-dRAST achieved 92.1% categorical agreement (CA), 95.3% essential agreement (EA), with 1.8% very major errors (VMEs), 3.5% major errors (MEs), and 5.2% minor errors (mEs). With colony isolates, it exhibited 92.5% CA and 95.1% EA, with 2.0% VMEs, 3.2% MEs, and 4.8% mEs. VITEK 2 showed 94.1% CA and 96.0% EA, with 4.3% VMEs, 0.4% MEs, and 4.3% mEs. QMAC-dRAST yielded elevated error rates for specific antimicrobial agents, with high VMEs for carbapenems and aminoglycosides. The median time to result for QMAC-dRAST was 5.9 h for PBCB samples and 6.1 h for subcultured colony isolates. Conclusions The QMAC-dRAST system demonstrated considerable strengths and comparable performance to the VITEK 2 system; however, challenges were discerned with specific antimicrobial agents, underlining a necessity for improvement.

The genus Enterococcus is increasingly recognized for its involvement in various human infections, with several species known to be pathogenic. This study characterized Enterococcus sp. SMC-9, isolated from bile of a patient with cholangitis, and compared its characteristics with those of Enterococcus montenegrensis CoE-012-22T, recently isolated from dried beef sausage. A comprehensive analysis, encompassing phylogenetic, genomic, and phenotypic studies, confirmed that strain SMC-9 belongs to the same species as E. montenegrensis CoE-012-22T. However, comparative genomic analysis revealed key differences in virulence and antibiotic resistance gene profiles between the two strains. Notably, genes related to exopolysaccharide biosynthesis and the L-rhamnose biosynthesis pathway were found exclusively in strain SMC-9, suggesting their role in the strain’s colonization of the biliary tract and its involvement in cholangitis. Additionally, the tetracycline resistance gene tet(M), which was absent in E. montenegrensis CoE-012-22T, was identified in strain SMC-9, explaining its high tetracycline minimum inhibitory concentration (>16 μg/mL). These findings highlight the unique pathogenic traits of strain SMC-9 compared to E. montenegrensis CoE-012-22T. Our study underscores the significant genetic and phenotypic variations that can exist among strains within the same species, highlighting the critical need for strain typing to assess their potential impact on patient outcomes and public health.

This study compared the performance of two commercial molecular assays, the STANDARD M10 Clostridioides difficile assay (M10) and the Xpert C. difficile assay (Xpert), for detecting toxigenic C. difficile in stool specimens. A total of 487 consecutive stool specimens submitted for routine C. difficile testing between June and November 2023 were included. Following routine testing using C. DIFF QUIK CHEK COMPLETE (QCC), M10 and Xpert were tested in parallel, alongside toxigenic culture (reference standard). Additionally, two-step algorithms, using QCC on the first step and either M10 or Xpert on the second step, were assessed. Both M10 and Xpert demonstrated a sensitivity and negative predictive value (NPV) of 100%. M10 exhibited significantly higher specificity and positive predictive value (PPV; 91.9% and 64.2%, respectively) than Xpert (90.3% and 59.8%, respectively). Both two-step algorithms showed a sensitivity and NPV of 98.4% and 99.8%, respectively. The specificity and PPV of the two-step algorithm using M10 (95.2% and 75.0%, respectively) were slightly higher than those of the one using Xpert (94.8% and 73.2%, respectively), without statistical significance. Receiver operating characteristic curve analysis, assessing the predictive ability of cycle threshold (Ct) values for the detection of free toxin, exhibited an area under the curve of 0.825 for M10 and 0.843 for Xpert. This indicates the utility of Ct values as predictors for the detection of free toxin in both assays. In conclusion, M10 proves to be an effective diagnostic tool with performance comparable to Xpert, whether utilized independently or as part of a two-step algorithm.

ABSTRACT The aim of this study was to compare the performance of the newly developed SMG HHV-6 Q Real-Time PCR Kit (SMG assay) with the RealStar HHV-6 PCR Kit (RealStar assay). The analytical sensitivity and specificity, linearity, and precision of the SMG assay were evaluated. The clinical performance of the SMG assay was assessed and compared with that of the RealStar assay using 207 clinical specimens (HHV-6A positive, n = 51; HHV-6B positive, n = 64; HHV-6A/B negative, n = 92). The limit of detection of the SMG assay was 2.92 log 10 copies/mL for HHV-6A DNA and 2.88 log 10 copies/mL for HHV-6B DNA. The linear range was determined to be 3.40–9.00 log 10 copies/mL for both viruses. Intra- and inter-assay variability were below 5% at concentrations ranging from 4 to 9 log 10 copies/mL. No cross-reactivity was observed with the 25 microorganisms included in the specificity panel. The clinical sensitivity and specificity of the SMG and RealStar assays compared to in-house polymerase chain reaction and sequencing were as follows: SMG assay, 98.0% and 100% for HHV-6A DNA, respectively, and 96.9% and 100% for HHV-6B DNA, respectively; RealStar assay, 98.0% and 100% for HHV-6A DNA, respectively, and 90.6% and 100% for HHV-6B DNA, respectively. The correlation coefficients between viral loads measured by the two assays were 0.948 and 0.975, with mean differences of 0.62 and 0.32 log 10 copies/mL for HHV-6A and HHV-6B DNA, respectively. These results demonstrate that the SMG assay is a sensitive and reliable tool for the quantitative detection and differentiation of HHV-6A and HHV-6B DNA. IMPORTANCE Quantitative real-time PCR (qPCR) that can distinguish between HHV-6A and HHV-6B DNA is recommended for diagnosis of active infection. The SMG HHV-6 Q Real-Time PCR Kit (SMG assay) is a newly developed qPCR assay that can differentiate between HHV-6A and HHV-6B DNA; however, little is known about its performance. In this study, we assessed the performance of the SMG assay and compared it with that of a commercially available qPCR assay, the RealStar HHV-6 PCR Kit (RealStar assay). The SMG assay demonstrated excellent analytical sensitivity and specificity, precision, and linearity. Furthermore, the viral loads measured by the SMG assay were highly correlated with those measured by the RealStar assay. Our results suggest that the SMG assay is a useful diagnostic tool for quantitative detection and differentiation of HHV-6A and HHV-6B DNA.

ABSTRACT With the introduction of ceftazidime-avibactam worldwide, the antimicrobial activity of new β-lactam/β-lactamase inhibitors (BL/BLIs) needs to be investigated. From January 2020 to June 2023, Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacterales were collected. With a broth microdilution test of new BL/BLIs, cross-activity test with nine combinations of BLs and new BLIs and dose-escalation titration test for non-susceptible isolates were conducted to investigate inhibitory activities of new BLIs. A total of 188 isolates was collected and most isolates (186/188, 98.9%) carried the KPC-2 gene exclusively, while two isolates (1.1%) co-harbored NDM-1. Among the 186 KPC-2-producing isolates, 184 (98.9%) were susceptible to ceftazidime-avibactam, 173 (93.0%) to imipenem-relebactam, and 184 (98.9%) to meropenem-vaborbactam. All isolates non-susceptible to imipenem-relebactam or meropenem-vaborbactam became susceptible when avibactam replaced relebactam or vaborbactam, with 7 of 11 (63.6%) imipenem-relebactam non-susceptible isolates and both (100.0%) of the meropenem-vaborbactam non-susceptible isolates. When the minimum inhibitory concentrations (MICs) of BLs were compared using log 2 scales, combinations with avibactam showed statistically significant efficacy in lowering MICs compared to relebactam and vaborbactam (all P < 0.05). In the dose-escalation test of new BLIs, increasing dose of all new BLIs corresponded to increased susceptibility to BLs. Ceftazidime-avibactam exhibited excellent susceptibility against KPC-2-producing Enterobacterales unless co-harboring metallo-β-lactamase. The cross-combination test against non-susceptible isolates suggests that the inhibitory activity of avibactam was superior to those of relebactam or vaborbactam. Increasing the dose of new BLIs produced increased susceptibility to BLs, suggesting that high-concentration regimen need to be developed. IMPORTANCE This study investigated 188 Klebsiella pneumoniae carbapenemase (KPC)-2-producing Enterobacterales collected from January 2020 to June 2023 in a tertiary care hospital of Korea. Most isolates were susceptible to ceftazidime-avibactam (98.9%) and meropenem-vaborbactam (98.9%), while susceptibility to imipenem-relebactam was lower (93.0%). The cross-combination test using nine combinations of the individual β-lactams (BLs) and new β-lactamase inhibitors (BLIs) showed that the inhibitory activity of avibactam was significantly superior to relebactam or vaborbactam when the Log 2 MIC of BLs were compared for each combination with BLIs (all P < 0.05). The dose-escalation test of new BLIs demonstrated that increasing doses of new BLIs corresponded to increased susceptibility to BLs. Taken together, this study illustrates the excellent activity of ceftazidime-avibactam against KPC-2-producing Enterobacterales and suggests further investigation into high-concentration regimens for potentially non-susceptible clinical isolates.

Objective . We assessed the performance of the Humasis COVID-19 AgHS Test (Humasis, Korea), a novel antigen rapid diagnostic test (Ag-RDT) based on lateral fl ow immunoassay. Methods . 85 SARS-CoV-2-positive and 155 SARS-CoV-2-negative nasopharyngeal swab specimens con fi rmed by rRTPCR were tested using the Humasis and PBCheck Ag-RDTs. Th e analytical speci fi city of the Humasis AgRDT was evaluated using 27 strains of human respiratory pathogens. Results . Th e overall sensitivity and speci fi city were 72.9% and 99.4% for the Humasis Ag-RDT and 64.7% and 100% for the PBCheck AgRDT, respectively. Th e sensitivity for specimens with Ct <= 25 was 100% for both Ag-RDTs. Th e Humasis Ag-RDT showed no cross -reactivity with other respiratory pathogens. Conclusion . Our data suggests that the Humasis Ag-RDT can be a useful diagnostic tool for the detection of SARS-CoV-2 infection.

Volume 60, no. 3, p. 1932–1934, 2016, https://doi.org/10.1128/aac.02722-15. We hereby retract this article published in Antimicrobial Agents and Chemotherapy because of the presence of some errors in sequencing analysis for the published plasmids. Following the publication of the Expression of Concern (https://doi.org/10.1128/aac.02221-21), we recently reexamined the primary sequence data of pCC1409-1 and pCC1410-1 and found that there are some inaccuracies in the plasmid assembly and errors in the presentation of primers. Thus, we retract the paper, and we apologize to the readers and regret any inconvenience that this causes.

ABSTRACT In October 2022, we experienced a significant increase in samples showing high galactomannan (GM) indexes ranging from 6.22 to 10.58, as determined by the Platelia Aspergillus antigen immunoassay, also known as the GM test. After reviewing the medical records of nine GM antigenemia cases that did not show evidence of invasive aspergillosis, we found that these patients had received total parenteral nutrition (TPN) products from the same manufacturer, whose supplier of the glucose component had recently changed. The TPN products supplied by the specific manufacturer in October were subjected to a GM assay. The glucose component of the products from three different lot numbers exhibited strong positive results in the GM assay. Microbiological investigations through fungal culture and PCR on the TPN products were negative. The present study demonstrated that the glucose component of the TPN products contained a high level of GM antigen, which caused false-positive GM test results. The source of GM in the glucose component was glucoamylase, which was produced from Aspergillus niger to obtain glucose monohydrate from starch. Investigation of three commercially available glucoamylase products exhibited positive GM and 1,3-β-D-glucan tests with various titers positive up to 1:1,000 dilutions, while fungal cultures were all negative. Quality assurance measures of TPN products to prevent GM contamination should be emphasized during the manufacturing process to avoid unnecessary additional diagnostic procedures and overtreatment of invasive aspergillosis due to false-positive GM tests. IMPORTANCE This manuscript describes an occurrence of false-positive GM tests in patients receiving TPN products from a manufacturer who had recently changed the supplier of the glucose component. We describe the clinical presentation of nine false-positive cases and the results of serologic and microbiological investigations of the TPN products suspected of contamination with GM. Attempts to detect GM in parenteral nutrition products were made since the detection of GM in sodium gluconate-containing solutions in 2007, but none of them identified the source of elevated GM indexes in TPN products. However, the present study demonstrated that the glucose component of the TPN products contained a high level of GM antigen, which caused false-positive GM assay results. The source of GM was glucoamylase, which was derived from A. niger in the manufacturing process. Physicians and clinical microbiology laboratories should be aware of this issue to improve interpretation and patient care.

In the ongoing global fight against coronavirus disease 2019 (COVID-19), the sample preparation process for real-time reverse transcription polymerase chain reaction (rRT-PCR) faces challenges due to time-consuming steps, labor-intensive procedures, contamination risks, resource demands, and environmental implications. However, optimized strategies for sample preparation have been poorly investigated, and the combination of RNase inhibitors and Proteinase K has been rarely considered. Hence, we investigated combinations of several extraction-free protocols incorporating heat treatment, sample dilution, and Proteinase K and RNase inhibitors, and validated the effectiveness using 120 SARS-CoV-2 positive and 62 negative clinical samples. Combining sample dilution and heat treatment with Proteinase K and RNase inhibitors addition exhibited the highest sensitivity (84.26%) with a mean increase in cycle threshold (Ct) value of + 3.8. Meanwhile, combined sample dilution and heat treatment exhibited a sensitivity of 79.63%, accounting for a 38% increase compared to heat treatment alone. Our findings highlight that the incorporation of Proteinase K and RNase inhibitors with sample dilution and heat treatment contributed only marginally to the improvement without yielding statistically significant differences. Sample dilution significantly impacts SARS-CoV-2 detection, and sample conditions play a crucial role in the efficiency of extraction-free methods. Our findings may provide insights for streamlining diagnostic testing, enhancing its accessibility, cost-effectiveness, and sustainability.

Introduction: Poor liquefaction of pyogenic liver abscesses, which makes drainage impossible at the time of diagnosis, is not infrequent. The impact of poor liquefaction and sub-sequent drainage failure on clinical outcomes is unknown. Methods: We conducted a retrospective study with all patients diagnosed with liver abscesses from July 2017 through June 2020. Late drainage (LD) was defined as drainage performed >48 h after diagnosis due to poor liquefaction. Logistic regression was performed to identify the fac-tors associated with late or non-drainage (LD/ND). The Cox proportional hazard model was used to identify the variables related to abscess recurrence by 90 days after diagnosis. Results: A total of 153 patients were included. Thirty (19.6%) patients underwent LD and 54 (35.3%) did not undergo drainage. Other than non-cystic appearance, LD/ND was associated with smaller size (adjusted odds ratio [aOR] 0.85, 95% confidence interval [CI] 0.73-0.98, p = 0.031) and culture-negativity (aOR 2.69, 95% CI 1.14-6.67, p = 0.027). Current hepato-pancreaticobiliary malignancy was the only significant predictor of 90-day recurrence. Neither LD/ND (OR, 0.56; 95% CI, 0.13-2.41 ; p = 0.426) nor LD (OR, 1.26; 95% CI, 0.23-5.55 ; p = 0.719) was associated with recurrence by 90 days. The incidence of late complications was reduced by drainage, without a reduction in the duration of hospitalization.