Hospital water environment and antibiotic use: Key factors in a nosocomial outbreak of carbapenemase-producing Serratia marcescens

BACKGROUND

The healthcare water environment is a potential reservoir of carbapenem-resistant organisms (CROs). Here, we report the role of the water environment as a reservoir and the infection control measures applied to suppress a prolonged outbreak of Klebsiella pneumoniae carbapenemase-producing Serratia marcescens (KPC-SM) in two intensive care units (ICUs).

METHODS

The outbreak occurred in the ICUs of a tertiary hospital from October 2020 to July 2021. Comprehensive patient contact tracing and environmental assessments were conducted, and a case-control study was performed to identify factors associated with the acquisition of KPC-SM. Associations among isolates were assessed via pulsed-field gel electrophoresis (PFGE). Antibiotic usage was analyzed. .

RESULTS

The outbreak consisted of two waves involving a total of 30 patients with KPC-SM. Multiple environmental cultures identified KPC-SM in a sink, a dirty utility room, and a communal bathroom shared by the ICUs, together with the waste bucket of a continuous renal replacement therapy (CRRT) system. The genetic similarity of the KPC-SM isolates from patients and the environment was confirmed by PFGE. A retrospective review of 30 cases identified that the use of CRRT and antibiotics were associated with acquisition of KPC-SM (p < 0.05). There was a continuous increase in the use of carbapenems; notably, the use of colistin has increased since 2019.

CONCLUSION

Our study demonstrates that CRRT systems, along with other hospital water environments, are significant potential sources of resistant microorganisms, underscoring the necessity of enhancing infection control practices in these areas.

Incidence of Clostridioides difficile Infections in Republic of Korea: A Prospective Study With Active Surveillance vs. National Data From Health Insurance Review & Assessment Service

BACKGROUND

Since the emergence of hypervirulent strains of Clostridioides difficile, the incidence of C. difficile infections (CDI) has increased significantly.

METHODS

To assess the incidence of CDI in Korea, we conducted a prospective multicentre observational study from October 2020 to October 2021. Additionally, we calculated the incidence of CDI from mass data obtained from the Health Insurance Review and Assessment Service (HIRA) from 2008 to 2020.

RESULTS

In the prospective study with active surveillance, 30,212 patients had diarrhoea and 907 patients were diagnosed with CDI over 1,288,571 patient-days and 193,264 admissions in 18 participating hospitals during 3 months of study period; the CDI per 10,000 patient-days was 7.04 and the CDI per 1,000 admission was 4.69. The incidence of CDI was higher in general hospitals than in tertiary hospitals: 6.38 per 10,000 patient-days (range: 3.25-12.05) and 4.18 per 1,000 admissions (range: 1.92-8.59) in 11 tertiary hospitals, vs. 9.45 per 10,000 patient-days (range: 5.68-13.90) and 6.73 per 1,000 admissions (range: 3.18-15.85) in seven general hospitals. With regard to HIRA data, the incidence of CDI in all hospitals has been increasing over the 13-year-period: from 0.3 to 1.8 per 10,000 patient-days, 0.3 to 1.6 per 1,000 admissions, and 6.9 to 56.9 per 100,000 population, respectively.

CONCLUSION

The incidence of CDI in Korea has been gradually increasing, and its recent value is as high as that in the United State and Europe. CDI is underestimated, particularly in general hospitals in Korea.

Comparative Study on the Immunogenicity of COVID-19 mRNA Vaccines in Patients Receiving Adjuvant and Palliative Chemotherapy

This study was conducted to investigate potential differences in vaccine efficacy between patients undergoing palliative chemotherapy and receiving adjuvant chemotherapy. Additionally, the study proved the influence of vaccination timing on vaccine efficacy during active chemotherapy. Anti-receptor-binding domain (RBD) IgG binding antibody assays and surrogate neutralizing antibody assays were performed after BNT162b2 or mRNA-1273 vaccination in 45 solid cancer patients (23 adjuvant and 22 palliative chemotherapy) and in 24 healthy controls before vaccination (baseline), at every two to four weeks after the first (post-dose 1) and the second vaccination (post-dose 2). The levels of anti-RBD IgG and neutralizing antibodies increased significantly from baseline through post-dose 1 to post-dose 2 in all three groups. At the post-dose 1, the anti-RBD IgG and neutralizing antibody levels were significantly lower in cancer patients than in healthy controls. However, by post-dose 2, the seropositivity of anti-RBD IgG and neutralizing antibodies uniformly reached 100% across all groups, with no significant disparity in antibody levels among the three groups. Moreover, the antibody titers were not significantly different between patients with a vaccine and chemotherapy interval of more than 14 days or those with less than 14 days. This study demonstrated that after second doses of mRNA COVID-19 vaccines, humoral immune responses in patients receiving chemotherapy were comparable to those of healthy controls, regardless of whether the purpose of the anti-cancer treatment was palliative or adjuvant. Furthermore, the timing of vaccination did not affect the level of humoral immunity after the second vaccination.

Coinfection With Severe Fever With Thrombocytopenia Syndrome and Scrub Typhus in Korea

Background

Scrub typhus and severe fever with thrombocytopenia syndrome (SFTS) are the 2 most common tick-borne infectious diseases in Korea. Every year, an increasing number of cases are reported, which is a public health concern. Therefore, we aimed to investigate the prevalence of SFTS-scrub typhus coinfection in patients with SFTS.

Methods

Clinical samples were collected from 129 patients with SFTS. One-step reverse-transcription polymerase chain reaction (PCR) was performed to identify the SFTS virus (SFTSV), and real-time PCR followed by nested PCR was performed to detect the Orientia tsutsugamushi gene for scrub typhus. Phylogenetic analysis was conducted to confirm the evolutionary relationships among different species.

Results

Among 129 SFTS cases, 2 patients with SFTSV were positive for O. tsutsugamushi with a prevalence of coinfection of 1.6% (95% confidence interval, .001-.06). Phylogenetic analysis confirmed these as O. tsutsugamushi strain Boryong.

Conclusions

Our study found that 1.6% of patients were coinfected with SFTS and scrub typhus infection. We believe that this information will add a new dimension to clinical diagnosis, which should be considered for better public health management. Further research is needed to better understand the ecological transmission dynamics and geographical distribution of SFTSV and O. tsutsugamushi in endemic countries.

Clinical Characteristics and Risk Factors for Mortality in Critical COVID-19 Patients Aged 50 Years or Younger During Omicron Wave in Korea: Comparison With Patients Older Than 50 Years of Age

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic has caused the death of thousands of patients worldwide. Although age is known to be a risk factor for morbidity and mortality in COVID-19 patients, critical illness or death is occurring even in the younger age group as the epidemic spreads. In early 2022, omicron became the dominant variant of the COVID-19 virus in South Korea, and the epidemic proceeded on a large scale. Accordingly, this study aimed to determine whether young adults (aged ≤ 50 years) with critical COVID-19 infection during the omicron period had different characteristics from older patients and to determine the risk factors for mortality in this specific age group.

METHODS

We evaluated 213 critical adult patients (high flow nasal cannula or higher respiratory support) hospitalized for polymerase chain reaction-confirmed COVID-19 in nine hospitals in South Korea between February 1, 2022 and April 30, 2022. Demographic characteristics, including body mass index (BMI) and vaccination status; underlying diseases; clinical features and laboratory findings; clinical course; treatment received; and outcomes were collected from electronic medical records (EMRs) and analyzed according to age and mortality.

RESULTS

Overall, 71 critically ill patients aged ≤ 50 years were enrolled, and 142 critically ill patients aged over 50 years were selected through 1:2 matching based on the date of diagnosis. The most frequent underlying diseases among those aged ≤ 50 years were diabetes and hypertension, and all 14 patients who died had either a BMI ≥ 25 kg/m² or an underlying disease. The total case fatality rate among severe patients (S-CFR) was 31.0%, and the S-CFR differed according to age and was higher than that during the delta period. The S-CFR was 19.7% for those aged ≤ 50 years, 36.6% for those aged > 50 years, and 38.1% for those aged ≥ 65 years. In multivariate analysis, age (odds ratio [OR], 1.084; 95% confidence interval [CI], 1.043-1.127), initial low-density lipoprotein > 600 IU/L (OR, 4.782; 95% CI, 1.584-14.434), initial C-reactive protein > 8 mg/dL (OR, 2.940; 95% CI, 1.042-8.293), highest aspartate aminotransferase > 200 IU/L (OR, 12.931; 95% CI, 1.691-98.908), and mechanical ventilation implementation (OR, 3.671; 95% CI, 1.294-10.420) were significant independent predictors of mortality in critical COVID-19 patients during the omicron wave. A similar pattern was shown when analyzing the data by age group, but most had no statistical significance owing to the small number of deaths in the young critical group. Although the vaccination completion rate of all the patients (31.0%) was higher than that in the delta wave period (13.6%), it was still lower than that of the general population. Further, only 15 (21.1%) critically ill patients aged ≤ 50 years were fully vaccinated. Overall, the severity of hospitalized critical patients was significantly higher than that in the delta period, indicating that it was difficult to find common risk factors in the two periods only with a simple comparison.

CONCLUSION

Overall, the S-CFR of critically ill COVID-19 patients in the omicron period was higher than that in the delta period, especially in those aged ≤ 50 years. All of the patients who died had an underlying disease or obesity. In the same population, the vaccination rate was very low compared to that in the delta wave, indicating that non-vaccination significantly affected the progression to critical illness. Notably, there was a lack of prescription for Paxlovid for these patients although they satisfied the prescription criteria. Early diagnosis and active initial treatment was necessary, along with the proven methods of vaccination and personal hygiene. Further studies are needed to determine how each variant affects critically ill patients.

Clinically differential diagnosis of human granulocytic anaplasmosis and severe fever with thrombocytopenia syndrome

This study analyzed HGA and SFTS in patients with suspected tick-borne infection by focusing on key differences that clinicians can easily recognize. A retrospective analysis was performed on confirmed patients with HGA or SFTS in 21 Korean hospitals from 2013 to 2020. A scoring system was developed by multivariate regression analysis and accuracy assessment of clinically easily discriminable parameters was performed. The multivariate logistic regression analysis revealed that sex (especially male sex) (odds ratio [OR] 11.45, P = 0.012), neutropenia (< 1500) (OR 41.64, P < 0.001), prolonged activated partial thromboplastin time (OR 80.133, P < 0.001), and normal C-reactive protein concentration (≤ 1.0 mg/dL; OR 166.855, P = 0.001) were significantly associated with SFTS but not with HGA. Each factor, such as meaningful variables, was given 1 point, and a receiver-operating characteristic curve with a cutoff value (> 1) in a 5-point scoring system (0-4 points) was analyzed to evaluate the accuracy of differentiation between HGA and SFTS. The system showed 94.5% sensitivity, 92.6% specificity, and an area under the receiver-operating characteristic curve of 0.971 (0.949-0.9). Where HGA and SFTS are endemic, the scoring system based on these four parameters such as sex, neutrophil count, activated partial thromboplastin time, and C-reactive protein concentration will facilitate the differential diagnosis of HGA and SFTS in the emergency room in patients with suspected tick-borne infectious diseases.

Replacement of the Dominant ST191 Clone by ST369 Among Carbapenem-Resistant Acinetobacter baumannii Bloodstream Isolates at a Tertiary Care Hospital in South Korea

The clonal dissemination of carbapenem-resistant Acinetobacter baumannii (CRAB) bacteremia is a serious clinical problem worldwide. However, the factors related to the emergence and replacement of predominant CRAB clones in nosocomial settings are unclear. By multilocus sequence typing (MLST), we evaluated the genetic relatedness of CRAB bloodstream isolates at a tertiary care hospital over a 3.5-year period and investigated the clinical and microbiologic characteristics of the predominant sequence types (STs). One hundred and seventy-nine CRAB bloodstream isolates were collected from June 2016 to December 2019, and their MLSTs according to Oxford scheme and clinical data were obtained. The predominant STs were assessed for in vitro growth, competitive growth, and virulence in a mouse model of intraperitoneal infection. Two dominant clones—ST369 (n = 98) and ST191 (n = 48)—belonging to international clone 2 (IC2) were recovered from patients admitted to intensive care units (ICUs) or wards. ST191 predominated (61%, 27/43) from June 2016 to July 2017, whereas ST369 (72%, 98/136), which was first isolated from a patient admitted to the emergency room, replaced ST191 (15%, 21/136) after August 2017. In a multivariate analysis, leukopenia (OR = 3.62, 95% CI 1.04–12.6, p = 0.04) and ST191 or 369 (OR = 5.32, 95% CI 1.25–22.65, p = 0.02) were independent risk factors for 7-day mortality. Compared with non-ST369, ST369 was associated with a shorter time to bacteremia from ICU admission (7 vs. 11 days, p = 0.01), pneumonia as an origin of bacteremia (67 vs. 52%, p = 0.04), leukopenia (28 vs. 11%, p &lt; 0.01), and a lower 7-day survival rate (41 vs. 70%, p &lt; 0.01). In vitro, ST 369 isolates had significantly higher growth rates and enhanced competitive growth compared to ST191. Finally, ST369 had greater virulence and a higher mortality rate than other STs in a mouse infection model. We report almost-complete replacement of the predominant ST191 clone by ST369 within an 8-month period at our hospital. ST369 had a high incidence density rate of CRAB bacteremia, a short time to bacteremia after ICU admission, and a high early mortality rate, which may be in part explained by its faster competitive growth rate and higher virulence than ST191.

Nosocomial Outbreak of COVID-19 from a Kidney Transplant Patient: Necessity of a Longer Isolation Period in Immunocompromised Patients

BACKGROUND

Determination of the release from isolation for coronavirus disease 2019 (COVID-19) in immunocompromised patients who need additional hospitalization for treatment of non-COVID-19 related disease is important to prevent nosocomial transmission. However, there is insufficient evidence for an extended isolation period.

MATERIALS AND METHODS

In September 2021, when the Delta variant was dominant, a nosocomial outbreak of COVID-19 occurred in the nephrology ward of a tertiary hospital in Gwangju, Korea. We conducted epidemiological investigations and whole-genome sequencing (WGS) of this virus.

RESULTS

A man who underwent kidney transplantation was admitted to our hospital for the treatment of acute kidney injury. He was diagnosed with asymptomatic COVID-19 infection during a pre-admission screening test on September 1, 2021 and underwent isolation. After 10 days of isolation in the COVID-19-designated ward, he was transferred to the general nephrology ward. He underwent steroid pulse therapy (September 17 to September 23, >60 mg/day prednisolone) due to acute T-cell rejection. On September 28, 2021, the first patient with COVID-19 was identified in the nephrology ward, and a rapid-response team was activated to identify additional patients with COVID-19 and prevent the spread of COVID-19. Epidemiological investigations revealed that 12 patients, two caregivers, and three healthcare workers from the nephrology ward were diagnosed with COVID-19. The WGS of specimens from 14 nosocomial outbreak samples and released an index patient exhibited the same Delta variant originating from the B.1.617.2 lineage. This hospital-acquired COVID-19 outbreak in the nephrology ward resulted in two (11.7%) deaths in patients who underwent kidney transplantation.

CONCLUSION

We demonstrated that an immunocompromised patient can cause a nosocomial outbreak due to the prolonged shedding of infectious viruses. Prolonged isolation in patients under active immunosuppressive therapy may be necessary to prevent transmission, especially in the hospital setting.

Weight Gain and Lipid Profile Changes in Koreans with Human Immunodeficiency Virus undergoing Integrase Strand Transfer Inhibitor-Based Regimens

Background

This study explored the relationship between integrase strand transfer inhibitor (INSTI)-based anti-retroviral agents and weight gain over time, and the risk factors for weight gain in Korean people living with human immunodeficiency virus (PLWH).

Materials and Methods

The study was conducted retrospectively in PLWHs 18 years of age or older who took one of three INSTI-based single-tablet regimens (STRs) (tenofovir disoproxil fumarate/emtricitabine/elvitegravir/cobicistat [TDF/F/EVG/c], tenofovir alafenamide/emtricitabine/elvitegravir/cobicistat [TAF/F/EVG/c], and abacavir/lamivudine/dolutegravir [ABC/3TC/DTG]) for more than 2 years at three university-affiliated hospitals in South Korea from May 2014 to December 2020. Analysis was performed in the treatment-naïve and treatment-experienced groups, respectively.

Results

Individual INSTI-based STRs were associated with weight gain at the 24-month follow up in both treatment-naïve (n = 179) and treatment-experienced (n = 290) groups. Body mass index (BMI) categories changed over time for TAF/F/EVG/c and ABC/3TC/DTG, with significant increases in the rates of overweight and obesity in treatment-naïve patients, whereas there was no change for TDF/F/EVG/c. TAF/F/EVG/c significantly increased total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and triglyceride (TG) compared to other regimens over 24 months. In the treatment-naïve group, a baseline CD4⁺ T cell count <100 cells/mm³, human immunodeficiency virus (HIV) viral load (VL) ≥100,000 copies/mL, no physical exercise, and TAF/F/EVG/c (vs. TDF/F/EVF/c) were risk factors for ≥10% weight gain. In the treatment-experienced group, age <45 years, BMI <25 kg/m², and no physical exercise were risk factors for ≥5% weight gain.

Conclusion

INSTI-based STR continued to increase body weight at the 24-month follow up in treated and untreated Korean PLWH. Exercise, together with demographic-, HIV-, and anti-retroviral therapy-related factors, influenced weight gain. Therefore, when prescribing an INSTI-based STR, weight gain and metabolic changes should be closely monitored in PLWH with these risk factors.

Rifamycin resistance, rpoB gene mutation, and clinical outcomes of Staphylococcus species isolated from prosthetic joint infections in Korea

PURPOSE

We conducted an in vitro investigation of rifamycin activity against planktonic and biofilm states of Staphylococcus aureus and S. epidermidis isolated from patients with prosthetic join infection (PJIs), characterized their rpoB mutations, and analyzed the clinical outcomes of rifampin-resistant isolates.

METHODS

A total of 110 staphylococcal isolates were collected from patients with PJIs. Antimicrobials tested using the broth microdilution method included rifampin, rifabutin, rifapentine, and rifaximin. We evaluated rpoB gene mutations to identify rifampin resistance mechanisms. Clinical outcomes were assessed in rifampin-resistant isolates.

RESULTS

Among the 110 staphylococcal isolates, we detected 85 S. aureus (methicillin-resistant, 55%) and 25 S. epidermidis (methicillin-resistant, 100%) isolates. Seven S. aureus isolates and two S. epidermidis isolates were rifampin resistant (minimum inhibitory concentration [MIC], ≥ 2 μg/mL); these exhibited rpoB gene mutations. Among 78 rifampin-susceptible S. aureus isolates and 23 S. epidermidis isolates, 76 S. aureus isolates and all S. epidermidis isolates were highly susceptible (MIC ≤ 0.06 μg/mL) to other rifamycins. The rifampin, rifabutin, rifapentine, and rifaximin minimum biofilm bactericidal concentrations for ≥ 50% of isolates were 4, 1, 2, and 4 μg/mL for S. aureus and 1, 0.125, 0.25, and 0.5 μg/mL for S. epidermidis, respectively, among rifampin-susceptible isolates. Among nine patients bearing rifampin-resistant isolates, only three (33%) had successful outcomes.

CONCLUSIONS

Rifamycins other than rifampin show promising staphylococcal activity, including antibiofilm activity. Rifamycin-resistant staphylococci exhibit rpoB gene mutations.

Genomic characterization of nine Clostridioides difficile strains isolated from Korean patients with Clostridioides difficile infection

Background

Clostridioides difficile infection (CDI) is an infectious nosocomial disease caused by Clostridioides difficile, an opportunistic pathogen that occurs in the intestine after extensive antibiotic regimens.

Results

Nine C. difficile strains (CBA7201–CBA7209) were isolated from nine patients diagnosed with CDI at the national university hospital in Korea, and the whole genomes of these strains were sequenced to identify their genomic characteristics. Comparative genomic analysis was performed using 51 reference strains and the nine isolated herein. Phylogenetic analysis based on 16S rRNA gene sequences confirmed that all 60 C. difficile strains belong to the genus Clostridioides, while core-genome tree indicated that they were divided into five groups, which was consistent with the results of MLST clade analysis. All strains were confirmed to have a clindamycin antibiotic resistance gene, but the other antibiotic resistance genes differ depending on the MLST clade. Interestingly, the six strains belonging to the sequence type 17 among the nine C. difficile strains isolated here exhibited unique genomic characteristics for PaLoc and CdtLoc, the two toxin gene loci identified in this study, and harbored similar antibiotic resistance genes.

Conclusion

In this study, we identified the specific genomic characteristics of Korean C. difficile strains, which could serve as basic information for CDI prevention and treatment in Korea.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13099-021-00451-3.

Comparison of RT-PCR, RT-nested PCRs, and real-time PCR for diagnosis of severe fever with thrombocytopenia syndrome: a prospective study

We designed a highly sensitive reverse transcription nested polymerase chain reaction targeting the M-segment (NPCR-M) of severe fever with thrombocytopenia syndrome (SFTS) virus. NPCR-M was performed in parallel with three other referenced PCR assays QPCR-S, PCR-M, and NPCR-S to assess their clinical usefulness as routine diagnostic techniques for SFTS. In this multi-centered prospective study, 122 blood samples from 38 laboratory-confirmed SFTS patients and 85 control samples were used. The results demonstrated that QPCR-S and NPCR-S had better sensitivity rate up to 21 days after symptom onset however, the PCR-M showed poor sensitivity after 7 days of symptom onset. Our designed NPCR-M had a higher detection rate up to 40 days from symptom onset and revealed the persistence of SFTSV RNA in the early convalescent phase. No false-positive results were seen for the control samples. Additionally, NPCR-M showed positive results for a sample that initially showed negative results from other PCRs and for many other samples collected in the convalescent phase of SFTS. Our designed nested PCR is suitable for SFTSV detection in patients’ blood collected in the acute and early convalescent phase of SFTS, and shows better sensitivity and high specificity even up to 40 days after symptom onset.

Veno-arterial extracorporeal membrane oxygenation for severe fever with thrombocytopenia syndrome with fulminant myocarditis: a case report

Background

The clinical spectrum of severe fever with thrombocytopenia syndrome (SFTS) is wide, which can range from fever to multiple organ failure. Conservative therapy plays a key role in the treatment of SFTS. However, severe cases of SFTS, such as fulminant myocarditis, may require mechanical hemodynamic support.

Case presentation

This report presents a case of a 59-year old woman diagnosed with SFTS by reverse-transcription polymerase chain reaction. The patient had no initial symptoms of cardiac involvement and rapidly developed hemodynamic instability 3 days after hospitalization. She suffered from chest pain and had elevated cardiac enzymes. In the absence of atrio-ventricular conduction abnormalities, left ventricular dysfunction, and coronary artery abnormalities by coronary angiography, she was diagnosed with fulminant myocarditis. At that time, her pulse rate nearly dropped to 0 bpm and she developed near complete akinesia of the heart despite vasopressor administration. Veno-arterial extracorporeal membrane oxygenation (ECMO) was initiated with other supportive measures and she fully recovered after 21 days.

Conclusions

This case indicates that SFTS can cause fulminant myocarditis even without evidence of cardiac involvement at presentation. When symptoms and/or signs of acute heart failure develop in patients with SFTS, myocarditis should be suspected and the patient should be promptly evaluated. Additionally, mechanical hemodynamic support like ECMO can be a lifesaving tool in the treatment of fulminant myocarditis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06446-4.

Circulating Plasmacytoid and Conventional Dendritic Cells Are Numerically and Functionally Deficient in Patients With Scrub Typhus

Background

Dendritic cells (DCs) are specialized antigen-presenting cells known to bridge innate and adaptive immune reactions. However, the relationship between circulating DCs and Orientia tsutsugamushi infection is unclear. Therefore, this study aimed to examine the level and function of plasmacytoid DCs (pDCs) and conventional DCs (cDCs), two subsets of circulating DCs, in scrub typhus patients.

Methods

The study included 35 scrub typhus patients and 35 healthy controls (HCs). pDC and cDC levels, CD86 and CD274 expression, and cytokine levels were measured using flow cytometry.

Results

Circulating pDC and cDC levels were found to be significantly reduced in scrub typhus patients, which were correlated with disease severity. The patients displayed increased percentages of CD86⁺ pDCs, CD274⁺ pDCs, and CD274⁺ cDCs in the peripheral blood. The alterations in the levels and surface phenotypes of pDCs and cDCs were recovered in the remission state. In addition, the production of interferon (IFN)-α and tumor necrosis factor (TNF)-α by circulating pDCs, and interleukin (IL)-12 and TNF-α by circulating cDCs was reduced in scrub typhus patients. Interestingly, our in vitro experiments showed that the percentages of CD86⁺ pDCs, CD274⁺ pDCs, and CD274⁺ cDCs were increased in cultures treated with cytokines including IFN-γ, IL-12, and TNF-α.

Conclusions

This study demonstrates that circulating pDCs and cDCs are numerically deficient and functionally impaired in scrub typhus patients. In addition, alterations in the expression levels of surface phenotypes of pDCs and cDCs could be affected by pro-inflammatory cytokines.

Effects of steroid therapy in patients with severe fever with Thrombocytopenia syndrome: A multicenter clinical cohort study

BACKGROUND

Severe fever with thrombocytopenia syndrome (SFTS) is an acute, febrile, and potentially fatal tick-borne disease caused by the SFTS Phlebovirus. Here, we evaluated the effects of steroid therapy in Korean patients with SFTS.

METHODS

A retrospective study was performed in a multicenter SFTS clinical cohort from 13 Korean university hospitals between 2013 and 2017. We performed survival analysis using propensity score matching of 142 patients with SFTS diagnosed by genetic or antibody tests.

RESULTS

Overall fatality rate was 23.2%, with 39.7% among 58 patients who underwent steroid therapy. Complications were observed in 37/58 (63.8%) and 25/83 (30.1%) patients in the steroid and non-steroid groups, respectively (P < .001). Survival analysis after propensity score matching showed a significant difference in mean 30-day survival time between the non-steroid and steroid groups in patients with a mild condition [Acute Physiology and Chronic Health Evaluation II (APACHE II) score <14; 29.2 (95% CI 27.70-30.73] vs. 24.9 (95% CI 21.21-28.53], P = .022]. Survival times for the early steroid (≤5 days from the start of therapy after symptom onset), late steroid (>5 days), and non-steroid groups, were 18.4, 22.4, and 27.3 days, respectively (P = .005).

CONCLUSIONS

After steroid therapy, an increase in complications was observed among patients with SFTS. Steroid therapy should be used with caution, considering the possible negative effects of steroid therapy within 5 days of symptom onset or in patients with mild disease (APACHE II score <14).

Prosthetic valve endocarditis by Trichosporon mucoides: A case report and review of literature

NATIONALE

Trichosporon species are widely distributed in nature and are emerging opportunistic human pathogens. Trichosporon infections are associated with superficial cutaneous involvement in immunocompetent individuals to severe systemic disease in immunocompromised patients. Until now, there is no report in infective endocarditis by Trichosporon mucoides confirmed by molecular diagnostics PATIENT CONCERNS:: A 66-year-old man presented with a fever that had occurred for a period of 6 months. He had undergone aortic valve replacement 10 years prior. Transthoracic echocardiography showed vegetations on the prosthetic aortic valve and native mitral valve. T mucoides was detected in the cultures of blood and vegetations.

DIAGNOSIS

DNA sequencing using D/D2 region of rRNA and internal transcribed spacer were performed.

INTERVENTIONS

Infections were successfully controlled with valve replacement and voriconazole plus liposomal amphotericin B therapy.

OUTCOMES

There has been no sign of recurrence for 18-months after treatment completion.

LESSONS

This is the first reported case of infective endocarditis due to T mucoides. Clinicians should consider Trichosporon species as causative agents of endocarditis in patients who have undergone cardiac surgery.

Air and Environmental Contamination Caused by COVID-19 Patients: a Multi-Center Study

BACKGROUND

The purpose of this study was to determine the extent of air and surface contamination of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) in four health care facilities with hospitalized coronavirus disease 2019 (COVID-19) patients.

METHODS

We investigated air and environmental contamination in the rooms of eight COVID-19 patients in four hospitals. Some patients were in negative-pressure rooms, and others were not. None had undergone aerosol-generating procedures. On days 0, 3, 5, and 7 of hospitalization, the surfaces in the rooms and anterooms were swabbed, and air samples were collected 2 m from the patient and from the anterooms.

RESULTS

All 52 air samples were negative for SARS-CoV-2 RNA. Widespread surface contamination of SARS-CoV-2 RNA was observed. In total, 89 of 320 (27%) environmental surface samples were positive for SARS-CoV-2 RNA. Surface contamination of SARS-CoV-2 RNA was common in rooms without surface disinfection and in rooms sprayed with disinfectant twice a day. However, SARS-CoV-2 RNA was not detected in a room cleaned with disinfectant wipes on a regular basis.

CONCLUSION

Our data suggest that remote (> 2 m) airborne transmission of SARS-CoV-2 from hospitalized COVID-19 patients is uncommon when aerosol-generating procedures have not been performed. Surface contamination was widespread, except in a room routinely cleaned with disinfectant wipes.

Antimicrobial susceptibility of Staphylococcus species isolated from prosthetic joints with a focus on fluoroquinolone-resistance mechanisms

We investigated susceptibility to antimicrobials of 89 staphylococcal species from PJIs and analyzed fluoroquinolone (FQ)-resistance mechanisms. Staphylococcal isolates showed high resistance to oral antimicrobials, with the exception of TMP-STX and linezolid. The main mechanism of resistance to FQ was mutations in quinolone-resistance-determining-regions. Fifteen percent of Staphylococcus aureus overexpressed efflux-pump genes.

Viral Load Kinetics of SARS-CoV-2 Infection in Saliva in Korean Patients: a Prospective Multi-center Comparative Study

BACKGROUND

This study was performed to compare the viral load and kinetics of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) in saliva with those in standard nasopharyngeal/oropharyngeal (NP/OP) swabs.

METHODS

Fifteen patients with SARS-CoV-2 infection from four hospitals were prospectively enrolled and matched samples of nasopharyngeal/oropharyngeal swabs and saliva were collected at Day 1 of admission and every other day till consequently negative for two times. Real-time reverse transcription polymerase chain reaction (rRT-PCR) was performed to detect the envelope (E) and RNA-dependent RNA polymerase (RdRP) genes.

RESULTS

The cycle threshold values of saliva were comparable to those of NP/OP swabs overall (P = 0.720, Mann-Whitney U test). However, the overall sensitivity of rRT-PCR using saliva was 64% (34/53), which is lower than the 77% (41/53) using NP/OP swabs. The sensitivity of rRT-PCR using saliva was especially lower in early stage of symptom onset (1-5 days; 8/15; 53%) and in patients who did not have sputum (12/22; 55%).

CONCLUSION

Saliva sample itself is not appropriate for initial diagnosis of coronavirus disease 2019 (COVID-19) to replace NP/OP swabs, especially for the person who does not produce sputum. COVID-19 cannot be excluded when the test using saliva is negative, and it is necessary to retest using NP/OP swabs.

Microbial Etiology of Pyogenic Vertebral Osteomyelitis According to Patient Characteristics

Background

It is difficult to select an appropriate empirical antibiotic treatment regimen for patients with culture-negative pyogenic vertebral osteomyelitis (PVO). Having knowledge of the distribution of microorganisms according to patient characteristics can help clinicians make informed choices regarding empirical antibiotics. The aim of this study was to determine the microbial distribution among individuals with PVO according to their demographic and clinical characteristics.

Methods

We reviewed the medical records of patients admitted to our hospital with culture-confirmed PVO between January 2005 and December 2017 and collected data on demographics, underlying diseases, and radiographic and microbiological results. Statistical analysis was performed to identify associations between specific bacteria and specific patient characteristics.

Results

A total of 586 patients were included in the study. The prevalence of Staphylococcus aureus infections was higher in young patients than in old patients, while gram-negative bacterial infections and Enterococcus were more prevalent in older patients. Gram-negative bacterial infections were more common in women than in men (32.1% vs 16.4%; P < .05), in patients with cirrhosis than in those without (32.7% vs 21.1%; P < .05), and in patients with a solid tumor than in those without (31.0% vs 20.7%; P < .05). Methicillin-resistant S. aureus infections were more prevalent in patients with chronic renal disease than in those without (34.4% vs 14.7%; P < .05).

Conclusions

The microbial etiology of PVO varies according to patient characteristics. Patient characteristics should thus be considered when choosing empirical antibiotics in patients with culture-negative PVO.

Viral kinetics of SARS-CoV-2 in asymptomatic carriers and presymptomatic patients

From a total of 71 laboratory-confirmed cases, three presymptomatic patients and 10 patients with entirely asymptomatic infections were identified. In two of the three incubation period patients, the viral titer in the presymptomatic period was very high (Ct value<20). The median number of days to first negative RT-PCR in the asymptomatic carriers was 4.5 (range 2.5-9), and all asymptomatic carriers reached a first RT-PCR Ct>35 within 14 days after diagnosis. Patients who have COVID-19 may already be infectious before there are symptoms, and 14 days of isolation after diagnosis may be sufficient in entirely asymptomatic cases.

Clinical characteristics and risk factors for complications of candidaemia in adults: Focus on endophthalmitis, endocarditis, and osteoarticular infections

OBJECTIVES

This study evaluated the incidence, risk factors, and clinical characteristics of complications of candidaemia in adults, with a focus on endophthalmitis, endocarditis, and osteoarticular infections.

METHODS

All patients ≥18 years old with candidaemia in two Korean tertiary hospitals from 2007 to 2016 were investigated. Complications of candidaemia were defined as the presence of endophthalmitis, endocarditis, or osteoarticular infections documented in patients with candidaemia. The clinical characteristics and risk factors for candidaemia with complications were analysed in the patients who underwent ophthalmological examinations.

RESULTS

Of 765 adult patients with candidaemia, 34 (4.4%) met the definition of complications, including endophthalmitis in 29 (3.8%), endocarditis in 4 (0.5%), and osteoarticular infections in 3 (0.4%). Of the 225 patients who underwent ophthalmological examinations, 29 (12.9%) had endophthalmitis. Candida albicans was an independent risk factor for complicated candidaemia (OR, 5.12; 95% CI, 2.17-12.09; P < 0.001). Although the mortality rate was no higher in complicated candidaemia, the duration of antifungal therapy was longer (23.1 ± 17.6 vs. 16.4 ± 10.8 days, P = 0.042), and 13 patients (39.3%) underwent additional procedures or surgery.

CONCLUSIONS

Complications of candidaemia occurred in 4.4% of adult patients. C. albicans was an independent risk factor for complicated candidaemia in adults. Complications of candidaemia might need prolonged treatment and additional procedures or surgery. Therefore, careful evaluation and active treatment of candidaemia with complications should be encouraged.

Pneumocystis pneumonia after use of corticosteroids in a man with severe alcoholic hepatitis: A case report

RATIONALE

Severe alcoholic hepatitis (AH) has a very high mortality rate. Current guidelines recommend oral corticosteroids as first-line agents in individuals with severe AH to reduce short-term mortality. However, systemic corticosteroids have serious adverse effects. In individuals with AH, infection, which is one of the complications of steroid use, can result in serious outcomes, such as acute-on-chronic liver failure. Pneumocystis pneumonia (PCP) is a life-threatening opportunistic infection which may occur when high-dose corticosteroids are prescribed for more than 1 month. Therefore, when high-dose corticosteroids are used, providing PCP prophylaxis is warranted. Although trimethoprim-sulfamethoxazole (TMP-SMX) is the drug of choice for the prophylaxis of PCP, its hepatotoxicity limits its use in patients with severe AH who are on high-dose corticosteroids. Moreover, there is a lack of consensus on which drugs should be used for PCP prophylaxis in individuals with severe AH who are on glucocorticoid treatment. Herein, we report a case of a 43-year-old male with fatal PCP that occurred after the use of corticosteroids for severe AH.

PATIENT CONCERNS

A 43-year-old alcoholic man presented with a hematoma on his right leg. His liver function was poor, and he was he was diagnosed with severe AH and treated with oral corticosteroids for 26 days. After glucocorticoid treatment, he developed a productive cough.

DIAGNOSES

A sputum PCR test was positive for Pneumocystis jirovecii.

INTERVENTIONS

He was initially treated with TMP-SMX and required artificial ventilation.

OUTCOMES

He developed disseminated intravascular coagulation and multi-organ failure, and died 10 days after starting TMP-SMX.

LESSONS

To date, prevention of PCP in individuals with severe AH who are on corticosteroids has been overlooked. This case illustrates the need for prophylaxis of PCP in individuals with severe AH taking corticosteroids.

544. Clonal Spread of Two Sequence Types of Carbapenem-Resistant Acinetobacter baumannii Blood Isolates at a Tertiary Care Hospital in South Korea Over 2.5 Years

Background

The dissemination of carbapenem-resistant Acinetobacter baumannii (CRAB) became an urgent public health concern. A specific sequence type (ST) of A. bauamannii has been reported to be associated with severity of disease or mortality. This study aimed to determine the genetic relatedness of CRAB blood isolates cultured from patients at a tertiary care hospital and to investigate clinical characteristics and outcome of CRAB bacteremia.

Methods

CRAB blood isolates were collected between June 2016 and December 2018, and their clinical data were obtained. Multi-locus sequence test (MLST) was performed using the Oxford scheme, and the STs were assigned using the MLST database.

Results

Of the 126 CRAB blood isolates, 123 isolates which could be typed by MLST all belonged to clonal complex (CC) 92. During the entire period, ST369 (42.3%) was the most dominant, followed by ST191 (32.5%), ST784 (13.8%) and ST451 (4.1%). ST369 was firstly introduced in August 2017. ST191 (61.4%) was the most abundant during June 2016 to July 2017, whereas ST369 (65.8%) replaced ST191 (16.5%) since August 2017. The time interval between intensive care unit admission and bacteremia was shorter in ST369 than ST191 in multivariate analysis (day, median (Q1, Q3), ST369 6 (3, 9.8), ST191 9 (6, 17), Odd Ratio 0.87 (95% CI 0.76–0.99) P = 0.048 logistic regression). According to the ST, the 7-day and 30-day mortality rates were as follows; 46% and 65% in ST191, 50% and 62% in ST369, and 10.7% and 46.4% in the other STs. Patients infected by ST191 or 369 had significant higher 7-day mortality rates (ST191/369, 48.3% vs. the other STs 10.7%, P = 0.001 by log-rank test) and 30-day mortality rates (ST191/369, 63.2% vs. the other STs, 46.4%, P = 0.045 by log-rank test).

Conclusion

This study demonstrates the clonal spread of two STs at a tertiary care hospital in South Korea over 2.5 years. After the introduction of ST369, it replaced ST 191 and widely disseminated within a hospital. Two predominant STs were associated with poor outcome. Continuous surveillance are necessary to monitor the dissemination of these strains.

Disclosures

All authors: No reported disclosures.

260. Detection of Aspergillus fumigatus Infection in Mice with 2-Deoxy-2-[18F]fluorosorbitol

Background

Invasive aspergillosis is a major cause of infectious morbidity and mortality in immunocompromised patients.However, definitive diagnosis of invasive Aspergillus infection is still difficult due to the lack of a rapid, sensitive and specific diagnostic methods. In this studies, we investigated 2-deoxy-2-[¹⁸F]fluorosorbitol ([¹⁸F]FDS) which has been reported to be accumulated in Gram-negative bacteria but not in Gram-positive bacteria or healthy mammalian or cancer cells, for the imaging detection of Aspergullus fumigatus infections with PET in vivo.

Methods

[¹⁸F]FDS was synthesized by reduction of 2-deoxy-2-[¹⁸F]fluoro-d-glucose ([¹⁸F]FDG) using NaBH₄. When the reaction was complete, the mixture was adjusted to a pH value to 6.5–7.5. Subsequently, the solution was filtered directly into a sterile product vial through a Sep-Pak Alumina N cartridge with a sterile filter. The probe uptake assay was performed by incubating bacterial cell and fungi with [¹⁸F]FDS (20 µCi) at 37°C for 2 h. Female BALB/c were immunosuppressed with cyclophosphamide and cortisone acetate prior to A. fumigatus intranasal, intramuscular, brain infection. The mircoPET images were obtained at 2 h after i.v. injection of [¹⁸F]FDS in infected mice.

Results

In vitro uptake test revealed significantly higher accumulation of [¹⁸F]FDS at 2 hin A. fumigatus, C. albicans and R. oryzae rather than with bacterial strains (Figure 1). PET imaging of BALB/c mice with pulmonary A. fumigatus infections showed obvious accumulation of [¹⁸F]FDS in the infected lungs compared with control (Figure 2). [¹⁸F]FDS PET imaging also detected A. fumigatus muscle and brain infection in mice. In infected shoulder muscle of mice, [¹⁸F]FDS PET imaging showed high legion-to-background ratio at 2 h. (4.05 ± 1.59, Figure 3).

Conclusion

[¹⁸F]FDS PET study demonstrated stable uptake in infected tissue with A. fumigatus and rapid clearance from the blood and other organs. [¹⁸F]FDS could be a useful imaging probe visualizing the invasive aspergillosis in vivo.

Disclosures

All authors: No reported disclosures.

Dysfunction of Circulating Natural Killer T Cells in Patients With Scrub Typhus

Background

Human natural killer T (NKT) cells are known to serve as regulatory and/or effector cells in infectious diseases. However, little is known about the role of NKT cells in Orientia tsutsugamushi infection. Accordingly, the objective of this study was to examine the level and function of NKT cells in patients with scrub typhus.

Methods

This study included 62 scrub typhus patients and 62 healthy controls (HCs). NKT cell level and function in peripheral blood samples were measured by flow cytometry.

Results

Proliferation of NKT cells and their ability to produce interferon-γ and interleukin-4 (IL-4) were significantly lower in scrub typhus patients compared to those in HCs. However, circulating NKT cell levels were comparable between patients and HCs. Expression levels of CD69, programmed death-1 (PD-1), lymphocyte activation gene-3 (LAG-3), and T-cell immunoglobulin domain and mucin domain-containing molecule-3 (TIM-3) were significantly increased in scrub typhus patients. Elevated expression of CD69, PD-1, LAG-3, and TIM-3, impaired proliferation, and decreased IL-4 production by NKT cells were recovered in the remission phase.

Conclusions

This study demonstrates that circulating NKT cells are numerically preserved but functionally impaired in scrub typhus patients. In addition, NKT cell dysfunction is recovered in the remission phase.

Outcomes of Third-Generation Cephalosporin Plus Ciprofloxacin or Doxycycline Therapy in Patients with Vibrio vulnificus Septicemia: A Propensity Score-Matched Analysis

Background

Combination therapy with a third-generation cephalosporin (TGC) and a tetracycline analogue is recommended for Vibrio vulnificus infection. The combination of a TGC and ciprofloxacin has synergistic in vitro bactericidal activity against V. vulnificus. No clinical study has compared the standard regimen with TGC plus ciprofloxacin therapy for V. vulnificus infection.

Methods

Patients with a confirmed V. vulnificus infection at two medical centers in Korea from 1991 to 2016 were enrolled in this study. The patients were grouped according to the type of antibiotic administered. A retrospective propensity-score-matched case-control study of patients treated with TGC plus doxycycline or TGC plus ciprofloxacin was performed. The clinical characteristics and outcomes of the patients were analyzed.

Results

A total of 218 patients were confirmed to have V. vulnificus septicemia during the study, and the 30-day survival rate was 39% (85/218). The patients were classified into the following six treatment groups: TGC monotherapy (n = 82), TGC plus doxycycline therapy (n = 42), TGC plus ciprofloxacin therapy (n = 39), ciprofloxacin monotherapy (n = 14), other β-lactam monotherapy (n = 10), and other (n = 31). The survival rates of these groups were as follows: TGC monotherapy (35%), TGC plus doxycycline (38%), TGC plus ciprofloxacin (54%), ciprofloxacin monotherapy (29%), other β-lactam (20%), and other (39%). The 30-day survival rate showed no significant difference between the TGC plus doxycycline and TGC plus ciprofloxacin groups (log-rank test, P = 0.18). Among the 81 patients treated with TGC plus doxycycline or TGC plus ciprofloxacin, 12 per treatment group were selected by propensity-score matching. There was no significant difference in the baseline characteristics or the frequency of fasciotomy between the two groups. The 30-day survival rate showed no significant difference between the TGC plus doxycycline (50%) and TGC plus ciprofloxacin (67%) groups (log-rank test, P = 0.46).

Conclusion

Our data suggest that the outcome of TGC plus ciprofloxacin therapy was comparable to that of TGC plus doxycycline therapy in patients with V. vulnificus septicemia.

The combination of a third-generation cephalosporin (TGC) and ciprofloxacin has synergy in vitro bactericidal activity against V. vulnificus. No clinical study has compared the standard regimen with TGC plus ciprofloxacin therapy for V. vulnificus infection. A total of 218 patients were enrolled who are confirmed to have V. vulnificus septicemia in two medical centers in Korea from 1991 to 2016. The 30-day survival rate was 39% (85/218) for all patients, 38% (16/42) for TGC plus doxycycline and 54% (21/39) for TGC plus ciprofloxacin (log rank test, P = 0.18). A propensity score-matched analysis was performed and 12 per treatment groups were selected. The 30-day survival rate showed no significant difference between the TGC plus doxycycline (50%, 6/12) and TGC plus ciprofloxacin (67%, 4/12) groups (log-rank test, P = 0.46). The outcome of TGC plus ciprofloxacin therapy was comparable to that of TGC plus doxycycline therapy in patients with V. vulnificus septicemia.

Comparison of pyogenic postoperative and native vertebral osteomyelitis

BACKGROUND CONTEXT

Postoperative vertebral osteomyelitis (PVO) after spinal surgery is a clinical challenge. However, there is a paucity of evidence regarding the most likely etiologic organisms to guide the choice of empirical antibiotic therapy, and previous reports of treatment outcomes for PVO are scarce.

PURPOSE

To compare the microbiology, clinical characteristics, and outcomes of pyogenic PVO with native vertebral osteomyelitis (NVO).

STUDY DESIGN

Retrospective comparative study.

PATIENT SAMPLE

Patients with microbiologically proven vertebral osteomyelitis from three university-affiliated hospitals in South Korea between January 2005 and December 2015 with follow-up of at least 12 months after completion of antibiotics or until the patient was transferred. Patients who had a spine operation in the same location within 1 year of diagnosis, and all patients with remnant implants at the time of the vertebral osteomyelitis diagnosis, were defined as having PVO. The remainder of the patients was considered to have NVO. Spinal operations included discectomy, laminectomy, arthrodesis, and instrumentation for stabilization of the spine.

OUTCOME MEASURES

Overall mortality, neurologic outcomes, treatment failure, and relapse of infection.

METHODS

Demographic data, comorbidities, presenting symptoms, microbiological data, radiographic characteristics, laboratory data (including white blood cell counts, erythrocyte sedimentation rate, and C-reactive protein), surgical treatment, and neurologic outcomes for each patient were reviewed from electronic medical records and analyzed. Mortality rate, treatment failure, and relapse of infection were calculated for the two groups. Factors associated with treatment outcome were evaluated using univariate and multivariate logistic regression analyses.

RESULTS

The study evaluated 104 patients with PVO and 441 patients with NVO. In PVO, the most common isolate was Staphylococcus aureus (34%, n=35), followed by coagulase-negative staphylococci (31%, n=32). In NVO, the most common isolates were S. aureus (47%, n=206) and streptococci (21%, n=94). Of the staphylococci, the proportion of methicillin-resistant strains was significantly higher in PVO than that in NVO (75% vs. 39%, p<.001). The proportion of patients with gram-negative bacilli was 14% in PVO and 20% in NVO. Pre-existing or synchronous nonspinal infection was observed more frequently in NVO than in PVO (33% vs. 13%, p<.001). Although the duration of antibiotic use was similar in both groups, surgery for infection control was performed more frequently in PVO. The mortality rate was similar in both groups. However, the treatment failure and relapse rates at 12 months were higher in the PVO group (23% vs. 13%, p=.009; 14% vs. 7%, p=.028, respectively). Methicillin-resistant S.aureus was significantly associated with treatment failure or relapse via logistic regression (odds ratio 3.01, 95% confidence interval [1.71-5.32], p<.001; odds ratio 2.78, 95% confidence interval [1.40-5.49], p=.003).

CONCLUSIONS

Coverage of methicillin-resistant staphylococci should be considered when prescribing empirical antibiotics for PVO. Although surgery was performed more often in PVO than NVO, the treatment failure and relapse rates at 12 months were higher in PVO.

294. Spondylodiscitis After Spine Surgery: Microbiology, Clinical Findings, Outcome and Comparison With Spontaneous Spondylodiscitis

Background

Although postoperative spondylodiscitis has become a major problem, consensus on empirical antibiotics therapy is still controversial. To find out appropriate management of postoperative spondyodiscitis, this study investigated the microbiology, clinical characteristics, and outcome of postoperative pyogenic spondylodiscitis (P-PS) and compared with spontaneous pyogenic spondylodiscitis (S-PS).

Methods

This retrospective cohort study evaluated patients with microbiologically proven spondylodiscitis from three university-affiliated hospitals in South Korea between January 2005 and December 2015, with a follow-up of at least 12 months after completion of antibiotics or until the patient was transferred. Patients with prosthesis at the time of diagnosis of spondylodiscitis or who had a spine operation within 1 year of the diagnosis of spondylodiscitis were defined as having postoperative spondylodiscitis. The spine operations included discectomy, laminectomy, arthrodesis, and instrumentation for stabilization of the spine.

Results

The study evaluated 104 patients with P-PS and 441 patients with S-PS. In P-PS, the most common isolate was S. aureus (34%), followed by coagulase-negative staphylococci (31%), and the proportion of methicillin-resistant strains was 75%. In S-PS, the most common isolates were S. aureus (47%) and streptococci (21%). Of the staphylococci, 39% were methicillin resistant in S-PS. The proportion of patients with Gram-negative bacilli was 14% in P-PS and 20% in S-PS. Pre-existing or synchronous nonspinal infection (13% vs. 33%, P < 0.001) was observed more frequently in S-PS. Although the duration of antibiotic use was similar in both groups, surgical procedures were done more frequently in P-PS. The mortality rate was similar in both groups. However, the treatment failure and relapse rates at 12 months were higher in the P-PS group (23% vs. 13%, P = 0.009; 14% vs. 7%, P = 0.028, respectively). Methicillin-resistant S. aureus was associated with treatment failure or relapse.

Conclusion

Gram-positive organisms, mainly methicillin-resistant staphylococci, should be considered when prescribing empirical antibiotics in P-PS. Although surgical drainage was applied more often in P-PS than in S-PS, the treatment failure and relapse rates at the 12-month follow-up were higher in P-PS.

Disclosures

All authors: No reported disclosures.

1053. Biofilm Production and Clinical Characteristics of S. maltophilia Causing Persistent or Relapsing Bacteremia

Background

This study aimed to identify clinical or microbiological factors related to persistence or recurrence of Stenotrophomonas maltophilia bacteremia in adult patients.

Methods

S. maltophilia isolated from blood in two tertiary hospitals between 2011 and 2017 were investigated. Persistent bacteremia was defined as the consecutive blood culture positive for ≥5 days after initiation of appropriate antibiotics therapy. Relapse was defined as isolation of S. maltophilia from blood after completion of antibiotics treatment for the first episode of bacteremia. Biofilm formation was assessed in 96-well polystyrene plate with Trypticase Soy Broth using 0.5% crystal violet staining. The presence of smf-1 gene was detected by polymerase chain reaction.

Results

Of total 100 patients with S. maltophilia bacteremia, 10 of persistent, 8 of relapsing, and 46 of nonpersistent, nonrelapsing cases were investigated. The presence of indwelling urinary catheter (P = 0.011), nasogastric tube (P = 0.003), mechanical ventilator treatment (P = 0.001), and previous colonization of S. maltophilia (P = 0.016) were more frequently observed in patients with persistent bacteremia compared with nonpersistent, nonrelapsing bacteremia cases. In patients with relapsing bacteremia, hematologic malignancy (P = 0.022), neutropenia (P = 0.001), and concomitant isolation of S. maltophilia in clinical samples other than blood (P = 0.041) were more common than nonpersistent, nonrelapsing bacteremia patients. Catheter-related infection (37.0%) followed by pneumonia (28.3%) was the most common primary focus of nonpersistent, nonrelapsing bacteremia whereas pneumonia was the most frequent cause of bacteremia in both of persistent and relapsing cases (40.0% and 50.0%). Most of isolates (63 of 64) were susceptible to cotrimoxazole. The resistance to levofloxacin were comparable among isolates from persistent, relapsing and nonpersistent, nonrelapsing cases (10.0% vs. 12.5% vs. 15.2%, P = 0.988). Biofilm formation ability was not significantly different between three groups (optical density at 595, mean ± SD, 0.69 ± 0.34 vs. 0.78 ± 0.33 vs. 0.70 ± 0.33, P = 0.529). The smf-1 gene was found in all isolates.

Conclusion

More careful treatment approaches to patients with risk factors for S.maltophilia treatment failure should be warranted.

Disclosures

All authors: No reported disclosures.

Case report: dual primary AIDS-defining cancers in an HIV-infected patient receiving antiretroviral therapy: Burkitt's lymphoma and Kaposi's sarcoma

BACKGROUND

The incidence of AIDS-defining cancers (ADCs) has decreased markedly in the era of highly active antiretroviral therapy (HAART). The occurrence of two ADCs is rare in people living with HIV or AIDS (PWHA) who are severely immunosuppressed or have incomplete virologic suppression.

CASE PRESENTATION

We report a case of dual primary ADCs, especially NHL followed by KS, in a 70-year-old HIV-infected man who was on antiretroviral therapy and had successful virologic suppression. During HAART, he presented with generalized myalgia and abdominal pain. Multiple liver masses were detected and a biopsy revealed Burkitt's lymphoma. After three cycles of anticancer chemotherapy with a favorable response, he was diagnosed with cytomegalovirus retinitis and the anti-cancer chemotherapy was discontinued. Despite successful virologic suppression with HAART, human herpes virus-8 associated Kaposi's sarcoma was diagnosed in his right thigh. He underwent radiation therapy.

CONCLUSION

These findings suggest that multiple ADCs can occur in PWHA who are receiving HAART and have successful virologic suppression. Healthcare providers caring for PWHA should maintain vigilance for the development of a broad spectrum of cancers.

Factors affecting the clinical relevance of Corynebacterium striatum isolated from blood cultures

This study aimed to identify clinical or microbiological factors affecting the clinical relevance of Corynebacterium striatum isolated from blood cultures. A total of 64 isolates from 51 patients identified as C. striatum by matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and 16S rRNA gene sequencing were assessed. More than two blood cultures were positive in 25 (48.1%) patients. Diabetes, solid tumor, and a history of previous exposure to antibiotics were more common in patients with multiple positive blood cultures. Charlson comorbidity scores were also higher, and more isolates were recovered after 48 hours of hospital stay in patients with multiple positive blood cultures. Strains recovered from patients with multiple positive blood cultures produced significantly more biofilm. Based on multilocus sequence typing (MLST), sequence type (ST) 20 (31.3%) was the most dominant, followed by ST2 (20.3%) and ST23 (10.9%). There was no relationship between the number of positive blood culture sets and sequence typing. In multivariate analyses, Carlson comorbidity score (odds ratio [OR], 1.91; 95% confidence interval [CI], 1.09–3.36; P = 0.03) and biofilm formation were associated with multiple positive blood cultures (OR, 17.43; 95% CI, 3.71–81.91; P = 0.03). This study provides evidence that the biofilm phenotype could contribute to determining the clinical significance of C. striatum in patients with severe underlying conditions. The predominance of certain STs suggests the relatedness of C. striatum infection and the nosocomial environment.

Case report: detection of the identical virus in a patient presenting with severe fever with thrombocytopenia syndrome encephalopathy and the tick that bit her

Background

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne disease. Haemophysalis longicornis ticks have been considered the vector of severe fever with thrombocytopenia syndrome virus (SFTSV). However, clear data on the transmission of SFTS from ticks to humans are limited.

Case presentation

We report an 84-year-old woman who presented with fever and altered mentality, which was confirmed as SFTS with encephalopathy by reverse-transcription polymerase chain reaction in blood and cerebrospinal fluid. The SFTSV was also identified in the tick that bit her, H. longicornis. Phylogenetic analyses indicated that the SFTSV from the patient and the tick was identical. The patient gradually recovered with treatments of corticosteroids and immunoglobulin.

Conclusion

These findings provide further evidence of SFTS viral transmission from H. longicornis to human.

Disseminated Invasive Mycobacterium marinum Infection Involving the Lung of a Patient with Diabetes Mellitus

Mycobacterium marinum infection in humans occurs mainly as a granulomatous infection after exposure of traumatized skin to contaminated water. It is usually confined to the skin and soft tissue. Disseminated disease involving other organs rarely occurs in immunocompetent patients. Here, we report a case of disseminated M. marinum infection involving not only the cutaneous tissue, but also the lung of a male patient with uncontrolled diabetes and a previous history of steroid injection who was employed by a deep-water fishery.

Concordance of Results of Blood and Tissue Cultures from Patients with Pyogenic Spondylitis

Background

The aim of this study was to investigate the concordance of results of blood and tissue cultures in patients with pyogenic spondylitis.

Methods

We searched the patients with pyogenic spondylitis in whom micro-organisms were isolated from both blood and tissue cultures by retrospective review of medical records in three tertiary university-affiliated hospitals between January 2005 and December 2015. The species and antimicrobial susceptibility patterns of isolates from blood and tissue cultures were compared with each other.

Results

Among 141 patients with pyogenic spondylitis in whom micro-organisms were isolated from both blood and tissue cultures, the species of blood and tissue isolates were identical in 135 patients (95.7%, 135/141). Excluding the four anaerobic isolates, we investigated antimicrobial susceptibility patterns of 131 isolates of same species from blood and tissue cultures. Antibiotic susceptibility patterns were identical in 128 patients (97.7%, 128/131). The most common isolates were Staphylococcus aureus (86 patients; 85 concordant and 1 discordant), followed by streptococcus (24 patients; 22 concordant and 2 discordant), and Escherichia coli (8 patients; all concordant).

Conclusion

We suggest that a positive blood culture from patients with pyogenic spondylitis could preclude the need for additional tissue cultures, especially when S. aureus and streptococcus grew in blood cultures.

Disclosures

All authors: No reported disclosures.

In Vivo Efficacy of Tigecycline-based Therapy Against Vibrio vulnificus Sepsis: Comparison with pre-Existing Regimens

Background

The mortality of Vibrio vulnificus sepsis is still high, despite the application of various antibiotic regimens. In-vivo efficacy of tigecycline against V. vulnificus has not been examined.

Methods

Time-kill assay was performed to evaluate the presence of in-vitro antibiotic synergism. The cytotoxicity of V. vulnificus was measured by using the lactate dehydrogenase assay, and rtxA1 toxin gene transcription was measured by β-galactosidase assay. Subcutaneous injection of V. vulnificus was performed with 1 × 10⁸ CFU on iron-overloaded female BALB/c mouse, then intraperitoneal antibiotic therapy was initiated 2 hours after bacterial inoculation.

Results

In vitro time-kill assay reveals synergism between tigecycline and ciprofloxacin. Inhibitory effects of tigecycline on rtx A1 transcription (66%) and cytotoxicity (59%) were comparable to those of ciprofloxacin (64% and 53%), but superior to those of minocycline (76% and 69%) or cefotaxime (86% and 83%; P < 0.05, each). Survival of tigecycline-treated mice were significantly higher than those of mice treated by current regimens (P < 0.05, each; Table). At Vibrio vulnificus sepsis mice inoculating 1 × 10⁹ CFU, survival rate for tigecycline-plus-ciprofloxacin was significantly higher than that of tigecycline (0%; 0/19) or tigecycline-plus-cefotaxime (0%; 0/19) (P < 0.05, each; Table).

Conclusion

Tigecycline-plus-ciprofloxacin showed superior in-vivo efficacy to pre-existing regimens.

Disclosures

All authors: No reported disclosures.

Concordance of results of blood and tissue cultures from patients with pyogenic spondylitis: a retrospective cohort study

OBJECTIVES

To investigate the concordance of results of blood and tissue cultures in patients with pyogenic spondylitis.

METHODS

We searched for patients with pyogenic spondylitis in whom microorganisms were isolated from both blood and tissue cultures by retrospective review of medical records in three tertiary university-affiliated hospitals between January 2005 and December 2015. The species and antimicrobial susceptibility patterns of isolates from blood and tissue cultures were compared.

RESULTS

Among 141 patients with pyogenic spondylitis in whom microorganisms were isolated from both blood and tissue cultures, the species of blood and tissue isolates were identical in 135 patients (95.7%, 135/141). Excluding the four anaerobic isolates, we investigated antimicrobial susceptibility patterns of 131 isolates of the same species from blood and tissue cultures. Antibiotic susceptibility patterns were identical in 128 patients (97.7%, 128/131). The most common isolates were Staphylococcus aureus (86 patients; 85 concordant and one discordant), followed by streptococcus (24 patients; 22 concordant and two discordant), and Escherichia coli (eight patients; all concordant).

CONCLUSIONS

We suggest that a positive blood culture from patients with pyogenic spondylitis could preclude the need for additional tissue cultures, especially when S. aureus and streptococcus grew in blood cultures.

Activation, Impaired Tumor Necrosis Factor-α Production, and Deficiency of Circulating Mucosal-Associated Invariant T Cells in Patients with Scrub Typhus

BACKGROUND

Mucosal-associated invariant T (MAIT) cells contribute to protection against certain microorganism infections. However, little is known about the role of MAIT cells in Orientia tsutsugamushi infection. Hence, the aims of this study were to examine the level and function of MAIT cells in patients with scrub typhus and to evaluate the clinical relevance of MAIT cell levels.

METHODOLOGY/PRINCIPAL FINDINGS

Thirty-eight patients with scrub typhus and 53 health control subjects were enrolled in the study. The patients were further divided into subgroups according to disease severity. MAIT cell level and function in the peripheral blood were measured by flow cytometry. Circulating MAIT cell levels were found to be significantly reduced in scrub typhus patients. MAIT cell deficiency reflects a variety of clinical conditions. In particular, MAT cell levels reflect disease severity. MAIT cells in scrub typhus patients displayed impaired tumor necrosis factor (TNF)-α production, which was restored during the remission phase. In addition, the impaired production of TNF-α by MAIT cells was associated with elevated CD69 expression.

CONCLUSIONS

This study shows that circulating MAIT cells are activated, numerically deficient, and functionally impaired in TNF-α production in patients with scrub typhus. These abnormalities possibly contribute to immune system dysregulation in scrub typhus infection.

First Imported Case of Zika Virus Infection into Korea

Since Zika virus has been spreading rapidly in the Americas from 2015, the outbreak of Zika virus infection becomes a global health emergency because it can cause neurological complications and adverse fetal outcome including microcephaly. Here, we report clinical manifestations and virus isolation findings from a case of Zika virus infection imported from Brazil. The patient, 43-year-old Korean man, developed fever, myalgia, eyeball pain, and maculopapular rash, but not neurological manifestations. Zika virus was isolated from his semen, and reverse-transcriptase PCR was positive for the virus in the blood, urine, and saliva on the 7th day of the illness but was negative on the 21st day. He recovered spontaneously without any neurological complications. He is the first case of Zika virus infection in Korea imported from Brazil.

Successful treatment of rapidly progressing severe fever with thrombocytopenia syndrome with neurological complications using intravenous immunoglobulin and corticosteroid

Since the first report of severe fever with thrombocytopenia syndrome (SFTS) in China, diagnostic methods have evolved. Despite definitive diagnoses, SFTS management has focused on prevention and supportive care. Although conservative treatment is effective for mild cases, there is an urgent need for an effective therapeutic modality to treat severe cases because of the high mortality associated with these. In this study, we report two cases of SFTS with neurological manifestations that fully recovered after a combination treatment consisting of intravenous immunoglobulin and corticosteroid.

Combination therapy with lopinavir/ritonavir, ribavirin and interferon-α for Middle East respiratory syndrome

Since the first report of Middle East respiratory syndrome (MERS) in 2012 in Saudi Arabia, no standard treatment guideline has been set despite the virulence of MERS-coronavirus (CoV) and the high case-fatality rate. The outbreak in South Korea in 2015 demonstrates that MERS outbreaks can occur outside of the Middle East. The combination of ribavirin and interferon-α has been the most widely used therapy for this infection. However, due to the varying results of treatment with these drugs, a new antiviral combination regimen is urgently needed. This is a case report of use of lopinavir/ritonavir-based combination antiviral therapy for a patient with MERS-CoV infection.

Predictors of viral pneumonia in patients with community-acquired pneumonia

BACKGROUND

Viruses are increasingly recognized as major causes of community-acquired pneumonia (CAP). Few studies have investigated the clinical predictors of viral pneumonia, and the results have been inconsistent. In this study, the clinical predictors of viral pneumonia were investigated in terms of their utility as indicators for viral pneumonia in patients with CAP.

METHODS

Adult patients (≥ 18 years old) with CAP, tested by polymerase chain reaction (PCR) for respiratory virus, at two teaching hospitals between October 2010 and May 2013, were identified retrospectively. Demographic and clinical data were collected by reviewing the hospital electronic medical records.

RESULTS

During the study period, 456 patients with CAP were identified who met the definition, and 327 (72%) patients were tested using the respiratory virus PCR detection test. Viral pneumonia (n = 60) was associated with rhinorrhea, a higher lymphocyte fraction in the white blood cells, lower serum creatinine and ground-glass opacity (GGO) in radiology results, compared to non-viral pneumonia (n = 250) (p < 0.05, each). In a multivariate analysis, rhinorrhea (Odd ratio (OR) 3.52; 95% Confidence interval (CI), 1.58-7.87) and GGO (OR 4.68; 95% CI, 2.48-8.89) were revealed as independent risk factors for viral pneumonia in patients with CAP. The sensitivity, specificity, positive- and negative-predictive values (PPV and NPV) of rhinorrhea were 22, 91, 36 and 83%: the sensitivity, specificity, PPV and NPV of GGO were and 43, 84, 40 and 86%, respectively.

CONCLUSION

Symptom of rhinorrhea and GGO predicted viral pneumonia in patients with CAP. The high specificity of rhinorrhea and GGO suggested that these could be useful indicators for empirical antiviral therapy.

Update on the Epidemiology, Treatment, and Outcomes of Carbapenem-resistant Acinetobacter infections

Carbapenem-resistant Acinetobacter species are increasingly recognized as major nosocomial pathogens, especially in patients with critical illnesses or in intensive care. The ability of these organisms to accumulate diverse mechanisms of resistance limits the available therapeutic agents, makes the infection difficult to treat, and is associated with a greater risk of death. In this review, we provide an update on the epidemiology, resistance mechanisms, infection control measures, treatment, and outcomes of carbapenem-resistant Acinetobacter infections.

Differences in the clinical presentation and the frequency of complications between elderly and non-elderly scrub typhus patients

Age can affect the clinical features and severity of infectious disorders, such as scrub typhus. We performed this study to examine differences between elderly and non-elderly scrub typhus patients, and to identify risk factors predictive of disease outcomes. This retrospective study included patients admitted to a tertiary hospital with scrub typhus between 2001 and 2011. A total of 615 patients were enrolled in this study, 328 of which were >65 years of age. Of the elderly patients, 46.0% (151/328) experienced at least one complication compared to only 23.0% (66/287) in younger patients. A linear trend was observed between age and complication rates (p=0.002). The most common complication in elderly patients was acute kidney injury (75, 22.9%). Treatment failure was reported in 10 elderly patients (3.0%) compared to one non-elderly patient (0.3%). Mental confusion and dyspnea of clinical manifestations at admission were common in elderly patients. Frequency of fever, rash, and eschar were similar in both groups. The following four factors were significantly associated with severe scrub typhus in elderly patients: (1) white blood cell (WBC) counts>10,000/mm(3) (OR=2.569, CI=1.298-5.086), (2) MDRD GFR<60mL/min (OR=3.525, CI=1.864-6.667), (3) albumin≤3.0g/dL (OR=4.976, CI=2.664-9.294), and (4) acute physiology and chronic health evaluation II (APACHE II) score>10 points (OR=3.304, CI=1.793-60.87). Complications and mortality were more common in elderly patients, often associated with delays in diagnosis and treatment.

Was 2009 Pandemic Influenza A (H1N1) Mild Among Pregnant Korean Women?

Clinical and laboratory data from Western countries suggest that pregnant women are at an increased risk for severe illness and complications associated with 2009 pandemic influenza A (H1N1). However, previous data among Korean women suggested a less severe outcome. In this study performed at a single referral center in Korea, rates of admission, pneumonia, intensive care unit admission, and death related to 2009 pandemic influenza A (H1N1) were significantly higher in 33 pregnant women than in 723 nonpregnant women of reproductive age (p<0.05 each). We report two cases of 2009 pandemic influenza A (H1N1) in pregnant Korean women who were admitted to the intensive care unit because of severe pneumonia that led to maternal and fetal death in one of the patients. This case series suggests that pregnant Korean women were also at increased risk of severe illness and complications during the 2009 pandemic influenza A (H1N1) outbreak.

Diagnostic use of serum ferritin levels to differentiate infectious and noninfectious diseases in patients with fever of unknown origin

INTRODUCTION: In this study, we determined whether serum ferritin levels could be used to differentiate between fever of unknown origin (FUO) caused by infectious and noninfectious diseases.

METHODS: FUO patients were hospitalized at Chonnam National University Hospital between January, 2005 and December, 2011. According to the final diagnoses, five causes were identified, including infectious diseases, hematologic diseases, noninfectious inflammatory diseases, miscellaneous and undiagnosed.

RESULTS: Of the 77 patients, 11 were caused by infectious diseases, 13 by hematologic diseases, 20 by noninfectious inflammatory diseases, 8 by miscellaneous diseases, and 25 were undiagnosed. The median serum ferritin levels in infectious diseases was lower than those in hematologic diseases and (median (interquartile range) of 282.4 (149.0–951.8) ng/mL for the infectious disease group, 1818.2 (485.4–4789.5) ng/mL for the hematologic disease group, and 563.7 (399.6–1927.2) ng/mL for the noninfectious inflammatory disease group, p = 0.048, Kruskal–Wallis test). By comparison using the Mann–Whitney test, statistically significant differences were found only between the infectious disease and hematologic disease groups (p = 0.049) and between the infectious disease and groups (p = 0.04).

CONCLUSION: An optimal cutoff value of serum ferritin levels to predict FUO caused by a noninfectious disease (hematologic diseases, noninfectious inflammatory diseases) was established as 561 ng/mL.

Effect of the Tube Diameter Distribution on the High-Temperature Structural Modification of Bundled Single-Walled Carbon Nanotubes

We present results of a systematic high-resolution transmission electron microscopy study of the thermal evolution of bundled single-walled carbon nanotubes (SWNTs) subjected to approximately 4-h high-temperature heat treatment (HTT) in a vacuum at successively higher temperatures up to 2200 degrees C. We have examined purified SWNT material derived from the HiPCO and ARC processes. These samples were found to thermally evolve along very different pathways that we propose depend on three factors: (1) initial diameter distribution, (2) concomitant tightness of the packing of the tubes in a bundle, and (3) the bundle size. Graphitic nanoribbons (GNR) were found to be the dominant high-temperature filament in ARC material after HTT = 2000 degrees C; they were not observed in any heat-treated HiPCO material. The first two major steps in the thermal evolution of HiPCO and ARC material agree with the literature, i.e., coalescence followed by the formation of multiwall carbon nanotubes (MWNTs). However, ARC material evolves to bundled MWNTs, while HiPCO evolves to isolated MWNTs. In ARC material, we find that the MWNTs collapse into multishell GNRs. The thermal evolution of these carbon systems is discussed in terms of the diameter distribution, nanotube coalescence pathways, C-C bond rearrangement, diffusion of carbon and subsequent island formation, as well as the nanotube collapse driven by van der Waals forces.