Clinical Characteristics of Nocardiosis: a Multicenter Retrospective Study in Korea.

BACKGROUND: Nocardiosis is a rare, but potentially life-threatening condition. It is difficult to diagnose, and bacterial culture identification can be time consuming. We investigated the characteristics of nocardiosis and the suitability of the treatment approach in Korea. MATERIALS AND METHODS: This retrospective study was conducted at 5 medical institutions between 2011 and 2021. We reviewed the medical records of patients with microbiologically confirmed nocardiosis. Appropriate antibiotic selection was defined as follows: (1) selecting antibiotics according to the species, (2) if the species of Nocardia was unknown, trimethoprim-sulfamethoxazole-based therapy or linezolid-based therapy was administered, and (3) selection of antibiotics using the antibiotic susceptibility test. The appropriate treatment periods for antibiotics were defined as treatment maintained from 3 to 12 months, depending on involvement of the organs. Descriptive analysis and Fisher exact test were used. Statistical significance was set at P-values of <0.05. RESULTS: Thirty patients were enrolled. Of these patients, 18 (60.0%) were male. The median age was 70.5 years. Among the diagnosed patients, 12 (40.0%) had an immunocompromised status. Eight (30.0%) patients received optimal treatment for the appropriate treatment period. Appropriate dosing duration was observed in 3 of the 12 (25.0%) immunocompromised patients. There was no significant difference between the presence or absence of immunosuppression and the adequacy of treatment for nocardiosis (P = 1.000). Skin and soft tissue (14 patients) were most frequently involved in this study. Nocardia species (spp.) were isolated from culture at a median of 6.0 days. There were 7 cases with N. farcinica (23.3%). CONCLUSION: We found that 60.0% of the patients with nocardiosis did not have an immunocompromised status. Further, 26.7% of the total patients received adequate treatment for nocardiosis. The reasons for suboptimal management of nocardiosis in Korea are presumed to be diagnostic difficulties, lack of awareness about nocardiosis, and difficulties in selecting antibiotics for Nocardia spp. among clinicians. The lack of antibiotic susceptibility tests for Nocardia spp. could be the source of these problems. Nocardiosis should be suspected in cases of recurrent infections with skin and soft tissue, musculoskeletal, or respiratory system involvement with or without an immunocompromised status. Clinical microbiological support is required for the diagnosis and selection of antibiotics in Korea. High clinical index of suspicion and clinical microbiological support are required for the accurate diagnosis of nocardiosis in Korea.

Performance evaluation of STANDARD Q COVID-19 Ag home test for the diagnosis of COVID-19 during early symptom onset.

BACKGROUND: Surveillance and control of SARS-CoV-2 outbreak through gold standard detection, that is, real-time polymerase chain reaction (RT-PCR), become a great obstacle, especially in overwhelming outbreaks. In this study, we aimed to analyze the performance of rapid antigen home test (RAHT) as an alternative detection method compared with RT-PCR. METHODS: In total, 79 COVID-19-positive and 217 COVID-19-negative patients confirmed by RT-PCR were enrolled in this study. A duration from symptom onset to COVID-19 confirmation of <5 days was considered a recruiting criterion for COVID-19-positive cases. A nasal cavity specimen was collected for the RAHT, and a nasopharyngeal swab specimen was collected for RT-PCR. RESULTS: Sensitivity of the STANDARD Q COVID-19 Ag Home Test (SD Biosensor, Korea), compared with RT-PCR, was 94.94% (75/79) (95% [confidence interval] CI, 87.54%-98.60%), and specificity was 100%. Sensitivity was significantly higher in symptomatic patients (98.00%) than in asymptomatic (89.66%) patients (p-value = 0.03). There was no difference in sensitivity according to the duration of symptom onset to confirmation (100% for 0-2 days and 96.97% for 3-5 days, respectively) (p-value = 1.00). The RAHT detected all 51 COVID-19 patients whose Ct values were ≤25 (100%), whereas sensitivity was 73.33% (11/15) among patients with Ct values >25 (p-value = 0.01). CONCLUSION: The RAHT showed an excellent sensitivity for COVID-19-confirmed cases, especially for those with symptoms. There was a decrease in sensitivity when the Ct value is over 25, indicating that RAHT screening may be useful during the early phase of symptom onset, when the viral numbers are higher and it is more transmissible.

Identification and infection control of carbapenem-resistant Enterobacterales in intensive care units.

Infections with multidrug-resistant organisms among patients in intensive care units (ICUs) are associated with high mortality. Among multidrug-resistant organisms, carbapenem-resistant Enterobacterales (CRE) harbor important pathogens for healthcare-associated infections, including pneumonia, bacteremia, and urinary tract infections. Risk factors for CRE colonization include underlying comorbid conditions, prior antibiotics exposure, prior use of healthcare facilities, device use, and longer ICU stay. The mortality rate due to invasive CRE infection is 22%-49%, and CRE colonization is associated with an approximately 10-fold increased risk of CRE infection. Infection control measures include hand hygiene, contact precautions, minimizing the use of devices, and environmental control. Additionally, implementing active surveillance of CRE carriage should be considered in ICU settings.

Antibody Responses One Year after Mild SARS-CoV-2 Infection.

Understanding the long-term kinetics of antibodies in coronavirus disease 2019 (COVID-19) is essential in interpreting serosurvey data. We investigated the antibody response one year after infection in 52 mildly symptomatic patients with severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection, using three commercial immunoassays and a surrogate virus neutralization test (sVNT) kit. Anti-N pan-immunoglobulin (Ig), anti-S IgG, and anti-S1 IgG were detected in 43 (82.7%), 44 (84.6%), and 30 (57.7%), respectively. In 49 (94.2%), the antibody could be detected by either anti-N pan-Ig or anti-S IgG assay. In the sVNT, 30 (57.7%) had positive neutralizing activity. Despite waning immunity, SARS-CoV-2 antibodies can be detected up to one year after infection, even in mild COVID-19 patients.

Antibody Responses 8 Months after Asymptomatic or Mild SARS-CoV-2 Infection.

Waning humoral immunity in coronavirus disease patients has raised concern over usefulness of serologic testing. We investigated antibody responses of 58 persons 8 months after asymptomatic or mildly symptomatic infection with severe acute respiratory syndrome coronavirus 2. For 3 of 4 immunoassays used, seropositivity rates were high (69.0%-91.4%).

Investigation of a Mumps Outbreak in a Dental Clinic at a University Hospital.

BACKGROUND: The Korean Society of Infectious Diseases recommends non-mandatory vaccination of newly employed healthcare workers (HCWs) with 2 measles-mumps-rubella (MMR) vaccine doses. Here, we aimed to investigate the seroprevalence of mumps among HCWs exposed to index patients with mumps and the efficacy of MMR vaccination as postexposure prophylaxis (PEP) when a mumps outbreak was encountered among HCWs in a tertiary university hospital in Korea. MATERIALS AND METHODS: Four HCWs were diagnosed with mumps over a 4-day period in January 2016. Three were working at a dental clinic and one visited the clinic on the day of symptoms onset of the first patient. We investigated all HCWs who either worked in that dental clinic, visited the clinic, or being within 1.5 meter of the patients with mumps without wearing surgical masks. Seventy HCWs were exposed to 4 HCWs with mumps. We interviewed all the exposed HCWs to investigate mumps infection and MMR vaccination history; they were all tested for mumps IgG. RESULTS: Of the 70 exposed HCWs, 56 (80%) were females; the median age was 34 years (range 21-59 years) and 3 had a history of mumps infection. The vaccination status verification of mumps among the HCWs was unavailable. As for serologic testing, 54 (77.1%) were seropositive. Seropositivity rate for the mumps virus in males was significantly lower than that in females (50.0% vs. 83.9% respectively, P = 0.007). A lower seroprevalence of mumps was observed among HCWs aged ≥40 years than those aged <40 years; however, this difference was not significant (65.2% vs. 83.0%, P = 0.096). During the initial intervention, all exposed HCWs were vaccinated because the turnaround time for serologic testing was expected to be >2 days. Thirty-four (62.9%) of 54 seropositive HCWs and 16 seronegative HCWs were administered MMR vaccines as PEP and following this, no additional cases of mumps were encountered during the maximum incubation period. CONCLUSION: Of the exposed HCWs, 77.1% were mumps-seropositive. Seropositive rates differed according to factors such as age and sex. Eligible HCWs received a MMR vaccine as PEP and no additional mumps cases occurred during the incubation period. It was useful in our infection control activities during the mumps outbreak.

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

BACKGROUND: Several factors contribute to differences in Streptococcus pneumoniae serotype distribution. We investigated the serotype distribution and antimicrobial resistance of S. pneumoniae isolated between 2014 and 2016 in Korea. METHODS: We collected a total of 1,855 S. pneumoniae isolates from 44 hospitals between May 2014 and May 2016, and analyzed the serotypes by sequential multiplex PCR. We investigated the distribution of each serotype by patient age, source of the clinical specimen, and antimicrobial resistance pattern. RESULTS: The most common serotypes were 11A (10.1%), followed by 19A (8.8%), 3 (8.5%), 34 (8.1%), 23A (7.3%), and 35B (6.2%). The major invasive serotypes were 3 (12.6%), 19A (7.8%), 34 (7.8%), 10A (6.8%), and 11A (6.8%). Serotypes 10A, 15B, 19A, and 12F were more common in patients ≤5 years old, while serotype 3 was more common in patients ≥65 years old compared with the other age groups. The coverage rates of pneumococcal conjugate vaccine (PCV)7, PCV10, PCV13, and pneumococcal polysaccharide vaccine 23 were 11.8%, 12.12%, 33.3%, and 53.6%, respectively. Of the 1,855 isolates, 857 (46.2%) were multi-drug resistant (MDR), with serotypes 11A and 19A predominant among the MDR strains. The resistance rates against penicillin, cefotaxime, and levofloxacin were 22.8%, 12.5%, and 9.4%, respectively. CONCLUSIONS: There were significant changes in the major S. pneumoniae serotypes in the community. Non-PCV13 serotypes increased in patients ≤5 years old following the introduction of national immunization programs with the 10- and 13-polyvalent vaccines.

Prevalence and Risk Factors of Carbapenem-resistant Enterobacteriaceae Acquisition in an Emergency Intensive Care Unit in a Tertiary Hospital in Korea: a Case-Control Study.

BACKGROUND: Infections caused by carbapenem-resistant Enterobacteriaceae (CRE) are associated with high mortality rates and their treatment is difficult because treatment is limited to certain antibiotics, such as colistin and tigecycline. We aimed to perform active surveillance culture of CRE (ASC-CRE) to monitor the prevalence of CRE acquisition during intensive care unit (ICU) care and to examine the potential risk factors associated with CRE acquisition. METHODS: We conducted ASC-CRE on patients who were admitted to the ICU in the emergency room at a tertiary hospital. Rectal swabs were analyzed using methods established by the Centers for Disease Control and Prevention. To detect carbapenemase-producing CRE, a polymerase chain reaction assay to detect five carbapenemase genes (blaNDM, blaKPC, blaVIM, blaIMP-1, and blaOXA-48) was performed. RESULTS: There were 22 CRE acquisition in 21 patients (2.6%, 21/810) and the incidence of CRE acquisition was 4.3/1,000 person-days, respectively. The most common species detected was Klebsiella pneumoniae (72.7%, 16/22), and 9 carbapenemase-producing CREs (7 blaKPC and 2 blaNDM) were detected. Independent risk factors associated with CRE acquisition were men gender (adjusted odds ratio [aOR], 5.3; 95% confidence interval [CI], 1.3-21.3), history of admission within one year (aOR, 3.9; 95% CI, 1.2-12.1), co-colonization with multidrug-resistant Acinetobacter baumannii (aOR, 15.6; 95% CI, 3.6-67.8) and extended-spectrum ß-lactamases-producing bacteria (aOR, 4.7; 95% CI, 1.5-14.6), and exposure to glycopeptide antibiotics (aOR, 3.6; 95% CI, 1.3-9.9). CONCLUSION: The identification of patients with risk factors for CRE acquisition and early detection of CRE acquisition using ASC-CRE may be useful for CRE control.

Severe Fever with Thrombocytopenia Syndrome Patients with Hemophagocytic Lymphohistiocytosis Retrospectively Identified in Korea, 2008-2013.

The incidence of severe fever with thrombocytopenia syndrome (SFTS) has increased in Korea since a first report in 2013. We investigated whether SFTS existed before 2013 using real-time reverse transcription polymerase chain reaction and stored blood samples from febrile patients with thrombocytopenia. Four cases of SFTS were identified, with the earliest occurring in 2008.

Erratum: Correction of Author Information and Funding Source: Seroprevalence of Severe Fever with Thrombocytopenia Syndrome in Southeastern Korea, 2015.

[This corrects the article on p. 29 in vol. 32, PMID: 27914128.].

Prevalence of severe fever with thrombocytopenia syndrome virus in black goats (Capra hircus coreanae) in the Republic of Korea.

Severe fever with thrombocytopenia syndrome virus (SFTSV) is an emerging tick-borne pathogen in China, Japan, and the Republic of Korea (ROK). The aim of this study was to investigate the prevalence of SFTSV antigens and anti-SFTSV antibodies in black goats (Capra hircus coreanae) throughout the ROK. Sera were collected from 737 black goats in nine provinces in the ROK. Eighteen of 737 (2.4%) goat sera were positive for SFTSV on one-step reverse transcription nested polymerase chain reaction. The amplified 346-bp S segments of SFTSV sequences were classified into three genotypes (BG1, BG2, and BG3), and were included in the Japanese clade rather than the Chinese clade, based on phylogenetic analysis. Forty-three of 624 (6.9%) serum samples were seropositive for anti-SFTSV antibodies on enzyme-linked immunosorbent assay analysis. This study is the first to examine the molecular prevalence of SFTSV in goats and the first to perform serological detection of anti-SFTSV antibodies in livestock in the ROK. Moreover, the results indicate that SFTSV is widely distributed in goats and that additional monitoring for SFTSV is needed in livestock in the ROK.

Recovery Rates of Non-Tuberculous Mycobacteria from Clinical Specimens Are Increasing in Korean Tertiary-Care Hospitals.

Non-tuberculous mycobacteria (NTM) are being recognized increasingly as the causative agents of opportunistic infections in humans. This study investigated the epidemiologic trends of NTM recovery from various clinical specimens in 2 Korean tertiary-care hospitals. We reviewed the laboratory records of patient samples cultured for mycobacteria between 2009 and 2015 at 2 tertiary-care hospitals in Korea. The medical records for patients with positive NTM samples were also reviewed. During the study period, 144,540 specimens were cultured for mycobacteria. The proportion of NTM-positive samples increased from 23.3% in 2009 to 48.2% in 2015. The 2 most frequently isolated NTM were Mycobacterium intracellulare (38.3%) and M. avium (23.1%). The number of clinically significant diseases caused by NTM in inpatients and outpatients increased from 6.8 to 12.9 per 100,000 patients over the same period. The rates of recovery of NTM from clinical specimens and the number of patients with NTM infections increased significantly (P < 0.001, testing for trend) between 2009 and 2015.

Human Granulocytic Anaplasmosis as a Cause of Febrile Illness in Korea Since at Least 2006.

AbstractHuman granulocytic anaplasmosis (HGA) is a tick-borne rickettsial zoonosis with fever, thrombocytopenia, and leukopenia. HGA has been reported in Korea in 2013 but it is uncertain how long it has existed. A retrospective study was conducted on patients who underwent bone marrow examination due to fever and cytopenia, with no clear hematologic or microbiologic causes, from 2003 through 2012. Laboratory diagnosis was made by detecting 16S rRNA genes of Anaplasma phagocytophilum from the stored blood samples. Among the 70 patients, five (7.1%) HGA cases were found, and the earliest case dated back to 2006. Two cases met the diagnostic criteria of hemophagocytic lymphohistiocytosis (HLH) and were fatal. Although HGA has been prevalent in Korea since at least 2006, it is not always diagnosed and has posed a possible lethal health risk to the people in Korea. HGA should be considered as a cause of fever with cytopenia or HLH.

Seroprevalence of Severe Fever with Thrombocytopenia Syndrome in Southeastern Korea, 2015.

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne disease characterized by fever, thrombocytopenia and diarrhea. SFTS was firstly reported in Korea in 2013 but its seroprevalence in the country has yet to be investigated. Here, we investigate the seroprevalence of SFTS in a Korean population. A cross-sectional study was conducted on patients who had their sera tested for various reasons at a tertiary university hospital on particular days in May 2015. This study was conducted in a tertiary hospital in southeastern Korea. Total antibodies including immunoglobulin G (IgG) and immunoglobulin M (IgM), specific to SFTS virus (SFTSV) in serum samples were detected by a double-antigen sandwich enzyme-linked immunosorbent assay (ELISA). A total of 1,069 serum samples were tested. Median age was 59 years (range 12-96 years), and 51.5% were male. Overall, 22 patients (2.1%) were tested positive for anti-SFTSV antibodies. The SFTS seroprevalence increased significantly with age (P = 0.034). The seropositive rate of rural area was higher than that of urban area (7.7% vs. 1.9%, P = 0.040). Seropositive rates were not significantly different among underlying diseases. None of the antibody-positive patients showed typical symptoms or laboratory findings of SFTS at the time of sample collection. Results of real-time reverse transcription polymerase chain reaction (RT-PCR) were negative for all the seropositive patients. Our study shows 2.1% SFTS seroprevalence among the patients visiting a tertiary hospital in Korea. Seroprevalence is higher in older and rural population.

In vitro antiviral activity of ribavirin against severe fever with thrombocytopenia syndrome virus.

BACKGROUND/AIMS: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease caused by severe fever with thrombocytopenia syndrome virus (SFTSV), a novel bunyavirus. As yet, there is no effective antiviral therapy for SFTS. Ribavirin is a broad-spectrum antiviral agent, which has been tried for treatment of SFTS. In this study, antiviral activity of ribavirin against SFTSV has been investigated. METHODS: Vero cell-grown SFTSV strain Gangwon/Korea/2012 was treated with ribavirin at various concentrations. Antiviral activity of ribavirin was evaluated by inhibition of the SFTSV cytopathic effect in Vero cells and quantification of viral RNA load in culture supernatant using one-step real-time reverse transcription polymerase chain reaction. Cytotoxicity of ribavirin was determined by a tetrazolium-based colorimetric method. RESULTS: Ribavirin reduced SFTSV titers in a dose-dependent manner, with a half-maximal inhibitory concentration ranged from 3.69 to 8.72 µg/mL. Cytopathic effects were reduced as ribavirin concentration increased. No significant cytotoxicity was detected at ribavirin concentrations of ≤ 31.3 µg/mL. CONCLUSIONS: Ribavirin exhibited inhibitory activity against SFTSV replication in vitro, which suggests that ribavirin can be used as a potential antiviral agent for SFTS.

Severe Fever with Thrombocytopenia Syndrome in South Korea, 2013-2015.

BACKGROUND: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease that was recently identified in China, South Korea and Japan. The objective of the study was to evaluate the epidemiologic and clinical characteristics of SFTS in South Korea. METHODS/PRINCIPAL FINDINGS: SFTS is a reportable disease in South Korea. We included all SFTS cases reported to the Korea Centers for Disease Control and Prevention (KCDC) from January 2013 to December 2015. Clinical information was gathered by reviewing medical records, and epidemiologic characteristics were analyzed using both KCDC surveillance data and patient medical records. Risk factors for mortality in patients with SFTS were assessed. A total of 172 SFTS cases were reported during the study period. SFTS occurred throughout the country, except in urban areas. Hilly areas in the eastern and southeastern regions and Jeju island (incidence, 1.26 cases /105 person-years) were the main endemic areas. The yearly incidence increased from 36 cases in 2013 to 81 cases in 2015. Most cases occurred from May to October. The overall case fatality ratio was 32.6%. The clinical progression was similar to the 3 phases reported in China: fever, multi-organ dysfunction, and convalescence. Confusion, elevated C-reactive protein, and prolonged activated partial thromboplastin times were associated with mortality in patients with SFTS. Two outbreaks of nosocomial SFTS transmission were observed. CONCLUSIONS: SFTS is an endemic disease in South Korea, with a nationwide distribution and a high case-fatality ratio. Confusion, elevated levels of C-reactive protein, and prolonged activated partial thromboplastin times were associated with mortality in patients with SFTS.