Microbiological persistence in patients with Mycobacterium abscessus complex lung disease: The prevalence, predictors, and the impact on progression.

OBJECTIVES: Persistent growth of Mycobacterium abscessus complex (MABC) in the respiratory system is not uncommon and may indicate continuous infection of MABC lung disease (MABC-LD), but its prevalence, risk factors, and clinical impact have not been investigated. METHODS: The present study was conducted in two medical centers in northern Taiwan. We enrolled patients with MABC-LD and investigated the prevalence and predictors of persistent culture positivity (MABC-PP). Furthermore, we analyzed the association between MABC-PP and radiographic or clinical progression. RESULTS: Among 189 patients with MABC-LD, 58 were in the MABC-PP group. Independent predictors for MABC-PP included an increasing radiographic score and highest acid-fast stain (AFS) of strong positivity (3-4+) at initial diagnosis (compared with negative AFS). MABC-PP and highest AFS were independently associated with MABC-LD progression by the multivariable analysis model. The adjusted hazard ratio increased to 3.56 when the two independent factors existed. CONCLUSIONS: MABC-PP accounted for 30.7% and was predicted by initial AFS grade and radiographic score. Patients with MABC-PP, and highest AFS grade might have disease progression.

Impact of coronavirus disease 2019 (COVID-19) on antimicrobial resistance among major pathogens causing healthcare-associated infection.

BACKGROUND: Coronavirus disease 2019 (COVID-19) has caused great impact on healthcare systems, including antibiotic usage and multi-drug resistant (MDR) bacterial infections at hospitals. We aim to investigate the trends of antimicrobial resistance among the major pathogens causing healthcare-associated infection (HAI) at intensive care units (ICU). MATERIAL AND METHODS: The demographic characteristics of hospitalization, usage of antimicrobial agents, counted by half-an-year DID (defined daily dose per 1000 patient-days), and HAI density of five major MDR bacteria, including methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), carbapenem-resistant Acinetobacter baumannii (CRAB), carbapenem-resistant Klebsiella pneumoniae (CRKP), and carbapenem-resistant Pseudomonas aeruginosa (CRPA), of ICU patients at a medical center in Taiwan during January 2017 to December 2021 were collected and analyzed. RESULTS: The total antibiotic usage, counted by DID, had a significant increasing trend, before COVID-19 occurrence in 2017-2019, but no further increase during the pandemic period in 2020-2021. However, comparing the two time periods, antibiotics consumption was significantly increased during pandemic period. There was no significant change of HAI density in MRSA, VRE, CRAB, CRKP, and CRPA, comparing the pandemic to the pre-pandemic period. Although, CRKP and CRPA infection rates were increasing during the pre-pandemic period, there was no further increase of CRKP and CRPA HAI rates during the pandemic period. CONCLUSION: During COVID-19 pandemic, there was no significant increase in HAI density of five major MDR bacteria at ICU in Taiwan, despite increased antibiotic usage. Strict infection prevention measures for COVID-19 precautions and sustained antimicrobial stewardship probably bring these effects.

Clinical significance of mutations in dihydropteroate synthase in Pneumocystis jirovecii pneumonia among non-HIV-infected patients.

BACKGROUND: Dihydropteroate synthase (DHPS) mutations may be associated with trimethoprim-sulfamethoxazole resistance in Pneumocystis jirovecii pneumonia (PCP) and worse clinical outcomes. However, the clinical significance of DHPS mutations in PCP among non-human immunodeficiency virus (HIV)-infected patients remains unclear. METHODS: Patients with PCP in three tertiary referral hospitals in Taiwan between 2016 and 2020 were retrospectively enrolled. Two point mutations, Thr55Ala and Pro57Ser, in the DHPS protein were analysed. Patients with invalid DHPS mutations in the respiratory specimen, chronic respiratory failure, receiving endotracheal intubation for surgical intervention, HIV infection, Pneumocystis jirovecii colonisation, and no lactate dehydrogenase (LDH) data were excluded. The primary outcome was 30-day survival. RESULTS: A total of 215 patients were analysed. Mutants inside DHPS were found in 78 patients (36.3%) and 68 patients (31.6%) died within 30 days. A total of 214 patients (99.5%) received trimethoprim-sulfamethoxazole as the first-line treatment. The rates of mechanical ventilation, 30-day, and in-hospital mortality were similar between wild-type and mutant DHPS PCP. After adjusting for important confounders, LDH > 500 µ/L (adjusted hazard ratio [aHR] = 2.448, P = 0.001), pneumonia severity index > 135 mg/dL (aHR = 1.689, P = 0.049), and having solid tumours (aHR = 1.832, P = 0.034) were independently associated with higher mortality. In subgroup analysis, mutant DHPS PCP patients had less 30-day mortality among patients aged > 65 years (P = 0.049), with lymphopenia (P = 0.040), and those without solid tumour (P = 0.045). CONCLUSIONS: In non-HIV-infected PCP, point mutants inside DHPS may not be associated with trimethoprim-sulfamethoxazole treatment outcomes. Further prospective large-scale studies are warranted.

Performance assessment of the Bruker Biotyper MALDI-TOF MS for the identification of difficult-to-identify viridans group streptococci.

Differentiating Streptococcus pneumoniae among nonpneumococcal viridans group streptococci (VGS) is challenging in conventional laboratories. Therefore, we aimed to evaluate the performance of the latest Bruker Biotyper matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) system in identifying VGS by comparing the results to those of the specific gene sequencing approach. Clinical isolates were initially identified using the BD Phoenix system to identify Streptococcus species. The optochin test was used to distinguish nonpneumococcal VGS from S. pneumoniae. The species of individual reference strains and clinical isolates were determined by comparing the sequences of the 16S rDNA, gyrB, sodA, groESL, or coaE genes with those in the GenBank sequence databases. We evaluated the performance of the Bruker Biotyper MALDI-TOF MS in VGS identification using two different machines with three databases. We collected a total of 103 nonpneumococcal VGS and 29 S. pneumoniae blood isolates at a medical center in northern Taiwan. Among these isolates, only seven could not be identified at the species level by the specific gene sequencing approach. We found that none of the nonpneumococcal VGS isolates were misidentified as pneumococci by the latest Biotyper system, and vice versa. However, certain strains, especially those in the mitis and bovis groups, could still not be correctly identified. The latest Bruker Biotyper 4.1 (DB_10833) showed significant improvement in identifying VGS strains. However, a specific gene sequencing test is still needed to precisely differentiate the species of strains in the mitis and bovis groups.

Nontuberculous mycobacterial infection mimicking gynecologic malignancy in a woman living with HIV.

The weakened immune system in people living with HIV (PLWH) can lead to infectious diseases occurring more aggressively and mimicking the clinical manifestations of malignancies. Mycobacterium sherrisii, a slow-growing nontuberculous mycobacterium, may cause opportunistic infections among PLWH. We present a case of a 41-year-old woman who initially presented with fever, vaginal spotting, and a bulky pelvic mass, raising suspicion of uterine malignancy. Following a surgical resection, she was pathologically diagnosed with leiomyoma and endometriosis. However, during an event of needlestick injury, she was unexpectedly found to be HIV-infected and the CD4 count was 157 cells/µL at diagnosis, which prompted a diagnostic work-up for opportunistic infections. The diagnosis of disseminated M. sherrisii infection was confirmed through cultures and special staining of specimens obtained from the pelvic tumor and blood. Subsequently, she was treated with a combination of ethambutol, azithromycin, and levofloxacin. Two months after treatment, abdominal and pelvic computed tomography revealed no evidence of recurrent tumor or abscess formation. Given the frequent association of pelvic masses with gynecologic malignancies in women living with HIV, it can be challenging to differentiate between a cancerous lesion and an infectious process, emphasizing the need for meticulous investigations to minimize the potential for misdiagnosis.

Applicability of an in-house extraction protocol in a Bruker Biotyper matrix-assisted laser desorption/ionization time-of-flight mass spectrometry system for the identification of Streptococcus agalactiae from broth-enriched vaginal/rectal swab specimens.

BACKGROUND AND PURPOSE: Early laboratory identification of group B Streptococcus (GBS, Streptococcus agalactiae) in the birth canal of pregnant women is critical for prompt administration of antimicrobial therapy and may further reduce the mortality rate due to GBS neonatal infection. METHODS: A total of 164 vaginal/rectal swab specimens collected from pregnant women at 35-37 weeks of gestation were screened for GBS vaginal colonization. The matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS, Bruker Biotyper, Bruker Daltonik GmbH, Bremen, Germany) system was used to detect GBS from Carrot broth and LIM broth enrichment using an in-house extraction protocol. The results were compared to those by conventional broth-enriched culture/identification methods as the gold standard. BD MAX™ GBS assay (Becton Dickinson, Sparks, MD, USA) was also performed for Carrot broth-enriched specimen. Discordant results were investigated using the GeneXpert® GBS PCR assay (Cepheid Inc., Sunnyvale, CA, USA). RESULTS: Using the extraction protocol, 33 (20.1%) of the 164 specimens were positive in Carrot broth, and 19 (11.6%) were positive in LIM broth. Using the culture protocol, 38 (23.2%) samples in Carrot broth and 35 (21.3%) in LIM broth were positive. The sensitivity, specificity, and positive and negative predictive values using the extraction protocol in Carrot broth and LIM broth compared to the gold standard conventional culture/identification method were 86.8% and 50.0%, 100% and 100%, 100% and 100%, and 96.2% and 86.9%, respectively. CONCLUSIONS: The extraction protocol with MALDI-TOF MS from Carrot broth-enriched samples provides a more rapid turnaround time, lower cost, and acceptable sensitivity and specificity to correctly identify pathogens when compared to conventional culture/identification methods.

Prevalence, Associated Factors, and Appropriateness of Empirical Treatment of Trichomoniasis, Bacterial Vaginosis, and Vulvovaginal Candidiasis among Women with Vaginitis.

Trichomoniasis (TV), bacterial vaginosis (BV), and vulvovaginal candidiasis (VVC) are the most common causes of vaginitis. This study investigated the prevalence of these diagnoses, their associated factors, and the appropriateness of the empirical treatment. From March 25, 2019, to June 17, 2022, 429 women with symptoms or signs of vaginitis were enrolled in a hospital in northern Taiwan with 438 episodes of vaginitis. Vaginal swabs were collected for Gram's staining, in vitro cultures for Trichomonas vaginalis, bacteria, and yeasts, and multiplex PCR assay for TV, BV, and VVC. Their empirical treatments were recorded. Factors associated with different etiologies of vaginitis were sought in multivariable logistic regression models. The prevalence of TV, BV, and VVC were 2.1%, 22.8%, and 21.7%, respectively, while coinfections of BV and VVC, TV and BV, TV and VVC, and triple infection occurred in 5.0%, 0.2%, 0.2%, and 0.7%, respectively. Multivariable analyses revealed that having multiple sexual partners was associated with TV and BV (adjusted odds ratio [aOR] 9.756 and 3.246, respectively), while menopausal women were less likely to have VVC (aOR 0.184). Moreover, dysuria was associated with TV (aOR 4.981), vaginal itch and pelvic pain with VVC (aOR 3.223 and 0.425, respectively), and discharge pH > 4.5 with BV (aOR 1.767). Other clinical symptoms and pelvic examination features had limited value for differential diagnosis. Among the 78 empirical antifungal and metronidazole prescriptions, 55.2% were ineffective or unnecessary. Our study highlights the importance to integrate appropriate diagnostic tools into the clinical care of women with vaginitis. IMPORTANCE Vaginal complaints are widespread among women and are associated with emotional, physical, and economic burdens with challenges in their diagnosis and management. In this survey, we identified that 40% of vaginitis in Taiwan was caused by either trichomoniasis, bacterial vaginosis, vulvovaginal candidiasis, or a combination of these infections. Our data suggested that typical physical findings appeared infrequently among women with these infections and their empirical treatments were frequently inappropriate. Our findings highlighted the importance of integrating proper diagnostic tools into clinical practice to improve the diagnosis and management of vaginitis, as recommended by national and international guidelines.

Molecular epidemiology of bacteraemic vancomycin-resistant Enterococcus faecium isolates and in vitro activities of SC5005 and other comparators against these isolates collected from a medical centre in northern Taiwan, 2019-2020.

OBJECTIVES: The global prevalence of vancomycin-resistant Enterococcus faecium (VREfm) highlights the need for new anti-enterococcal agents. Here, we assessed the molecular epidemiology of clinical VREfm bacteraemic isolates from a medical centre in northern Taiwan in 2019-2020 and to evaluate their susceptibility to last-line antibiotics and a new antimicrobial agent, SC5005. METHODS: The molecular epidemiology of VREfm was investigated using van genotyping, MLST and PFGE. The susceptibilities of VREfm strains to antibiotics and SC5005 were determined using the agar dilution and broth microdilution methods. The capability of E. faecium to develop resistance to antibiotics and SC5005 was evaluated using frequency of resistance and multipassage resistance assays. The mode of action of SC5005 was assessed by time-kill, bacterial membrane integrity and membrane potential assays. RESULTS: All 262 VREfm isolates harboured vanA gene, and the most prevalent sequence type was ST17 (51%, n = 134, 84 pulsotypes), followed by ST78 (25%, n = 65, 54 pulsotypes). Additionally, we identified four new STs (ST2101, ST2102, ST2135 and ST2136) and observed the arrival of multidrug-resistant ST1885 in Taiwan. Moreover, SC5005 was effective against all VREfm isolates, including those non-susceptible to last-line antibiotics. SC5005 can disrupt and depolarize the bacterial membrane to kill E. faecium without detectable resistance. CONCLUSIONS: The findings provide insights into the latest epidemiology and resistance profiles of bacteraemic-causing VREfm in northern Taiwan. Additionally, SC5005 has the potential for development as a new therapeutic to treat VREfm infections.

A difficult-to-treat pleuropulmonary histoplasmosis in a patient with rheumatoid arthritis in Taiwan.

Amphotericin B and itraconazole are the primary agents for treating histoplasmosis. Newer azoles are alternatives for patients refractory to or intolerant of standard therapy. We report an 83-year-old woman with rheumatoid arthritis complicated with pleuropulmonary histoplasmosis who responded to liposomal amphotericin B, but progressed under voriconazole and posaconazole maintenance therapy.

Performance of two commercial multiplex polymerase chain reaction assays for the etiological diagnosis of sexually transmitted infections among men who have sex with men.

BACKGROUND AND PURPOSE: This study aimed to investigate the etiologies of sexually transmitted infections (STIs) among men who have sex with men (MSM) in Taiwan. METHODS: Two commercial assays, the BD MAX Chlamydia trachomatis (CT), Neisseria gonorrhoeae (GC), and Trichomonas vaginalis (TV) panel and the Allplex™ STI Essential assay (CT, GC, Mycoplasma genitalium [MG], Mycoplasma hominis [MH], Ureaplasma urealyticum [UU], Ureaplasma parvum [UP], and TV) were evaluated. During the first stage, urine and rectal swab samples from 168 patients were evaluated using the BD MAX assay, and the multiplex RT-PCR Allplex™ STI Essential assay was applied only to the patients with positive results on the BD MAX asay (n = 49). During the second stage, urine and rectal swab samples from 90 patients were evaluated using the BD MAX assay and the Allplex™ qPCR. RESULTS: The Allplex qPCR identified all CT, missed one and additionally one TV from the positive samples (n = 49) by the BD MAX assay in the first stage. At the second stage, both commercial assays showed similar detection rate of CT, NG or CT/NG coinfection (11.1%, 1.1% and 4.4% by the BD MAX assay; 10.0%, 1.1% and 2.2% by the Allplex qPCR). The positivity rates of MG, MH, and UU by the Allplex qPCR were 4.4%, 2.2%, and 12.2%, respectively, for urine samples and 10%, 13.3%, and 22.2%, respectively, for anal swab samples. CONCLUSIONS: High rates of STI-associated etiologies were observed in MSM. The positive rates were higher in rectal swabs than in urine samples.

Disseminated Mycobacterium chimaera infection in a patient with adult-onset immunodeficiency syndrome: case report.

BACKGROUND: Patients with adult-onset immunodeficiency syndrome due to anti-interferon-γ autoantibodies (AIGAs) are susceptible to disseminated Mycobacterium avium complex (MAC) infections. M. chimaera, a newly identified MAC species, is distinguished from the others due to the reduced virulence. Previous cases of disseminated M. chimaera infection have been linked to cardiothoracic surgery. Reports of disseminated M. chimaera in patients without a history of cardiothoracic surgery are rare. CASE PRESENTATION: A 57-year-old Asian man, previously healthy, presented with fever, dry cough, exertional dyspnea, and decreased appetite. The delayed resolution of pneumonia despite antibiotic treatment prompted further imaging studies and biopsies from the lung and lymph node. The fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) demonstrated intense uptake in lung consolidations and diffuse lymphadenopathy. Cultures of the specimens obtained from sputum, blood, stool, lung tissue, and lymph node grew M. chimaera. Further immunological evaluation disclosed the presence of neutralizing AIGAs, which possibly led to acquired immunodeficiency and disseminated M. chimaera infection. CONCLUSIONS: We herein present the first case of adult-onset immunodeficiency due to AIGAs complicated with disseminated M. chimaera infection. Further immunological evaluation, including AIGAs, may be warranted in otherwise healthy patients who present with disseminated mycobacterial infection.

Staphylococcus taiwanensis sp. nov., isolated from human blood.

A novel coagulase-negative Staphylococcus strain (NTUH-S172T) was isolated from human blood culture in Taiwan with preliminary identification of Staphylococcus saprophyticus. 16S rRNA gene analysis and multilocus sequence analysis (MLSA) showed that NTUH-S172T was most closely related to Staphylococcus haemolyticus. The average nucleotide identity and digital DNA-DNA hybridization values with the whole genome sequence were <95 % and<70 % when compared to the related species. Strain NTUH-S172T could be distinguished from S. haemolyticus by urease production and from Staphylococcus borealis by nitrate reduction. In addition, the matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) spectrum of NTHU-S172T was significantly different from that of S. haemolyticus, which could be used in clinical identification. In conclusion, it is proposed that this isolate represents a novel species, named Staphylococcus taiwanensis sp. nov., with type strain NTUH-S172T (=BCRC 81315T=JCM 34726T).

Mycobacterium gordonae infection in immunocompromised and immunocompetent hosts: A series of seven cases and literature review.

BACKGROUND/PURPOSE: Mycobacterium gordonae is a ubiquitous environmental mycobacteria and has been long considered an opportunistic pathogen, causing infections only in immunocompromised hosts. Cases of M. gordonae related infections in immunocompetent host have rarely been reported, and the pathogenicity of M. gordonae remained uncertain. METHODS: From January 2016 to December 2018, seven cases of M. gordonae infection were diagnosed and treated at National Taiwan University Hospital. RESULTS: Six cases had at least one underlying disease affecting immune status, while one case had no identifiable underlying disease. The sites of infection were lung (n = 3), skin and soft tissue (n = 3), and one had disseminated disease involving the lung and bone marrow. All patients were cured after anti-mycobacterial treatment, except one patient died of refractory leukemia. CONCLUSION: Compatible with the literature reports, we demonstrate that M. gordonae could be pathogenic and causing infection not only in the immunocompromised host, but also in the otherwise healthy population. Multi-antimicrobial combination and adequate source control could have good therapeutic effect for patients with M. gordonae infections.

Clustering of Streptococcus gallolyticus subspecies pasteurianus bacteremia and meningitis in neonates.

BACKGROUND/PURPOSE: Although Streptococcus gallolyticus subspecies pasteurianus (SGSP) is a rare pathogen in children, it can cause invasive infections among neonates and infants. Herein, we report bacteremia/meningitis caused by SGSP in three neonates and review the literature on bacteremia and/or meningitis caused by this organism. METHODS: Three neonates, referred from an obstetrics clinic within a 2-month period, presented with invasive SGSP infections. The bacterial isolates were analyzed using Bruker Biotyper MALDI-TOF, sequencing of 16S rRNA and sodA genes (encoding manganese dependent superoxide dismutase), and PCR restriction fragment length polymorphism assay of groESL gene. Molecular typing was performed to evaluate the genetic relatedness. RESULTS: The median onset age of infection in the three neonates was 3 days (range 2-5 days). They were delivered through cesarean section in the same operation room under different doctors, and were cared for by different nurses. Patient A presented with bacteremia, patient B with bacteremia and meningitis, and patient C with meningitis. Four isolates were identified as SGSP and were susceptible to penicillin G, cefotaxime, and vancomycin. All patients were treated with ampicillin plus cefotaxime for 14 days, and no complications were observed. The molecular typing results suggested that all isolates belonged to a single clone, which indicated the possibility of an outbreak in the obstetrics clinic. CONCLUSION: Infection by a rare pathogen such as SGSP in multiple patients belonging to a single healthcare unit indicates that detailed investigation and stringent infection control policy are necessary for preventing further outbreaks of such diseases.

High prevalence of sexually transmitted coinfections among at-risk people living with HIV.

BACKGROUND/PURPOSE: Concurrent sexually transmitted infections (STIs) are not uncommon in at-risk populations, for which control requires integrated testing, treatment and prevention. METHODS: From May, 2019 to February, 2020, multiplex real-time PCR assays were prospectively performed to detect Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG), and Trichomonas vaginalis (TV) in the urine and rectal/vaginal swab specimens collected from HIV-positive patients with a history of STIs or symptoms suggestive of STIs. Patients confirmed to have acquired STIs were treated according to treatment guidelines. RESULTS: During the study period, 430 participants (99.1% men who have sex with men and median age 37 years) were included. The overall prevalence of CT, NG, and/or TV infection was 30.0%, including 24.7%, 12.1%, and 0.2% for CT, NG, and TV infection, respectively. The factors associated with CT, NG, and/or TV infection were hepatitis B surface antigen (HBsAg) seropositivity (AOR, 2.76; 95% CI, 1.22-6.26), recently acquired hepatitis C virus (HCV) infection (AOR, 5.62; 95% CI, 1.99-15.88), using mobile dating application (AOR, 2.08; 95% CI, 1.13-3.83), and oral sex (AOR, 2.12; 95% CI, 1.04-4.32). The rates of CT, NG, and/or TV infection were 50.0% in participants with recent HCV infection, 44.2% in those with HBsAg positivity, and 35.9% in those with incident syphilis. Among participants completing test-of-cure visits, the microbiological cure rate was 91.7% and 90.0% for chlamydia and gonorrhea, respectively. CONCLUSION: HIV-positive participants had a high prevalence of CT and/or NG, especially those coinfected with viral hepatitis and syphilis. Our results strongly support integrated STI services in the population.

Multicenter evaluation of two chemiluminescence and three lateral flow immunoassays for the diagnosis of COVID-19 and assessment of antibody dynamic responses to SARS-CoV-2 in Taiwan.

This multicenter, retrospective study included 346 serum samples from 74 patients with coronavirus disease 2019 (COVID-19) and 194 serum samples from non-COVID-19 patients to evaluate the performance of five anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody tests, i.e. two chemiluminescence immunoassays (CLIAs): Roche Elecsys® Anti-SARS-CoV-2 Test (Roche Test) and Abbott SARS-CoV-2 IgG (Abbott Test), and three lateral flow immunoassays (LFIAs): Wondfo SARS-CoV-2 Antibody Test (Wondfo Test), ASK COVID-19 IgG/IgM Rapid Test (ASK Test), and Dynamiker 2019-nCoV IgG/IgM Rapid Test (Dynamiker Test). We found high diagnostic sensitivities (%, 95% confidence interval [CI]) for the Roche Test (97.4%, 93.4-99.0%), Abbott Test (94.0%, 89.1-96.8%), Wondfo Test (91.4%, 85.8-94.9%), ASK Test (97.4%, 93.4-99.0%), and Dynamiker Test (90.1%, 84.3-94.0%) after >21 days of symptom onset. Meanwhile, the diagnostic specificity was 99.0% (95% CI, 96.3-99.7%) for the Roche Test, 97.9% (95% CI, 94.8-99.2%) for the Abbott Test, and 100.0% (95% CI, 98.1-100.0%) for the three LFIAs. Cross-reactivity was observed in sera containing anti-cytomegalovirus (CMV) IgG/IgM antibodies and autoantibodies. No difference was observed in the time to seroconversion detection of the five serological tests. Specimens from patients with COVID-19 pneumonia demonstrated a shorter seroconversion time and higher chemiluminescent signal than those without pneumonia. Our data suggested that understanding the dynamic antibody response after COVID-19 infection and performance characteristics of different serological test are crucial for the appropriate interpretation of serological test result for the diagnosis and risk assessment of patient with COVID-19 infection.

Heterogeneity of Molecular Characteristics among Staphylococcus argenteus Clinical Isolates (ST2250, ST2793, ST1223, and ST2198) in Northern Taiwan.

Staphylococcus argenteus is an emerging pathogen that is recognized as non-pigmented Staphylococcus aureus. However, the molecular characteristics of S. argenteus and its virulence factors have not been well studied. The present study analyzed 96 isolates of S. argenteus recovered from blood. Identification of S. argenteus was based on results of MALDI-TOF MS and lacking crtM gene. All 96 isolates were methicillin-susceptible. Multilocus sequence typing (MLST) revealed four sequence types: ST2250 (n = 72), ST2793 (n = 12), ST1223 (n = 10), and ST2198 (n = 2). All 72 ST2250 isolates harbored CRISPR loci with polymorphism of direct repeats and spacers, but no other STs carried CRISPR loci. To date, ST2793 isolates have rarely been reported in other countries. Collagen-binding adhesin gene (cna) and staphylococcal enterotoxin type C (sec) were detected in 12 (100%) and 8 (67%) ST2793 isolates, respectively. ST1223 has been reported as food poisoning pathogens, and enterotoxin gene clusters (egc) were detected in all 10 isolates, while seb gene was detected in three isolates. Two ST2198 isolates carried bone sialoprotein-binding protein gene (bbp), belonging to agr type IV. Our focus on the heterogeneity of molecular characterization in four ST types of S. argenteus revealed that S. argenteus had been isolated as early as 2000. Each ST type of S. argenteus harbors particular genetic markers that may contribute to their virulence.