Severe Human Parainfluenza Virus Community- and Healthcare-Acquired Pneumonia in Adults at Tertiary Hospital, Seoul, South Korea, 2010-2019

The characteristics of severe human parainfluenza virus (HPIV)-associated pneumonia in adults have not been well evaluated. We investigated epidemiologic and clinical characteristics of 143 patients with severe HPIV-associated pneumonia during 2010-2019. HPIV was the most common cause (25.2%) of severe virus-associated hospital-acquired pneumonia and the third most common cause (15.7%) of severe virus-associated community-acquired pneumonia. Hematologic malignancy (35.0%), diabetes mellitus (23.8%), and structural lung disease (21.0%) were common underlying conditions. Co-infections occurred in 54.5% of patients admitted to an intensive care unit. The 90-day mortality rate for HPIV-associated pneumonia was comparable to that for severe influenza virus-associated pneumonia (55.2% vs. 48.4%; p = 0.22). Ribavirin treatment was not associated with lower mortality rates. Fungal co-infections were associated with 82.4% of deaths. Clinicians should consider the possibility of pathogenic co-infections in patients with HPIV-associated pneumonia. Contact precautions and environmental cleaning are crucial to prevent HPIV transmission in hospital settings.

Validation of a new risk stratification system-based management for methicillin-resistant Staphylococcus aureus bacteraemia: analysis of a multicentre prospective study

PURPOSE

Distinguishing between complicated and uncomplicated Staphylococcus aureus bacteraemia (SAB) is therapeutically essential. However, this distinction has limitations in reflecting the heterogeneity of SAB and encouraging targeted diagnostics. Recently, a new risk stratification system for SAB metastatic infection, involving stepwise approaches to diagnosis and treatment, has been suggested. We assessed its applicability in methicillin-resistant SAB (MRSAB) patients.

METHODS

We retrospectively analysed data of a 3-year multicentre, prospective cohort of hospitalised patients with MRSAB. We classified the patients into three risk groups: low, indeterminate, and high, based on the new system and compared between-group management and outcomes.

RESULTS

Of 380 patients with MRSAB, 6.3% were classified as low-, 7.6% as indeterminate-, and 86.1% as high-risk for metastatic infection. No metastatic infection occurred in the low-, 6.9% in the indeterminate-, and 19.6% in the high-risk groups (P < 0.001). After an in-depth diagnostic work-up, patients were finally diagnosed as 'without metastatic infection (6.3%)', 'with metastatic infection (17.4%)', and 'uncertain for metastatic infection (76.3%)'. 30-day mortality increased as the severity of diagnosis shifted from 'without metastatic infection' to 'uncertain for metastatic infection' and 'with metastatic infection' (P = 0.09). In multivariable analysis, independent factors associated with metastatic complications were suspicion of endocarditis in transthoracic echocardiography, clinical signs of metastatic infection, Pitt bacteraemia score ≥ 4, and persistent bacteraemia.

CONCLUSIONS

The new risk stratification system shows promise in predicting metastatic complications and guiding work-up and management of MRSAB. However, reducing the number of cases labelled as 'high-risk' and 'uncertain for metastatic infection' remains an area for improvement.

Quantitative Interferon-Gamma Releasing Assay in Predicting Tuberculosis in South Korean Military: A Retrospective Cohort Study

OBJECTIVES

The interferon-gamma releasing assay (IGRA) has been widely used to diagnose latent tuberculosis infection (TBI). However, there are limited data on the association between performance in the IGRA and risk of tuberculosis disease (TBD), as well as on the appropriate IGRA threshold for initiating TBI treatment.

METHODS

The analysis was performed using the IGRA results in the Korean Military Manpower Administration database (January 2017 - December 2021), and TBD cases reported to the Korean Military Medical Command (January 2017 - June 2023). All Korean candidates for 18-month military service underwent the IGRA in the pre-enlistment examination, and enlistees who tested positive (≥0.35 IU/mL) were advised to receive TBI treatment before enlistment.

RESULTS

From 2017 to 2021, 1,647,941 individuals were screened, with 29,574 testing positive for IGRA. Excluding non-enlistees, namely individuals with TBD before enlistment, 19,387 individuals were IGRA positive and 1,356,324 IGRA negative. Of the positives, 4,351 were excluded due to discontinued or ongoing TBI treatment at or after enlistment. During follow-up of 9,219 untreated and 5,818 treated positive individuals and 1,356,324 negatives, TBD occurred in 22 of the IGRA positive individuals (97.5/100,000 person-years [95% CI 61.1 - 147.7]), predominantly in the untreated group (18 cases, 130.1/100,000 person-years [95% CI 77.1 - 205.7]) compared to the treated group (4 cases, 45.9/100,000 person-years [95% CI 12.5 - 117.4]), while 57 cases occurred in the IGRA negative group (2.8/100,000 person-years [95% CI 2.2 - 3.6]). Elevating the cut-off of IGRA from 0.35 IU/mL to 1.33 IU/mL increased positive predictive value (0.2% vs. 0.4%, p=0.03), with insignificant loss of sensitivity (24% vs. 20%, p=0.69) and decreased numbers needing treatment from 790.5 to 415.3.

CONCLUSION

Elevated IGRA levels before enlistment are associated with risk of TBD during military service. It is worth considering raising the IGRA threshold for treatment of TBI in cohorts of healthy, young military individuals.

Marmosets as model systems for the study of Alzheimer's disease and related dementias: substantiation of physiological Tau 3R and 4R isoform expression and phosphorylation

INTRODUCTION

Marmosets have been shown to spontaneously develop pathological hallmarks of Alzheimer's disease (AD) during advanced age, including amyloid-beta plaques, positioning them as a model system to overcome the rodent-to-human translational gap for AD. However, Tau expression in the marmoset brain has been understudied.

METHODS

To comprehensively investigate Tau isoform expression in marmosets, brain tissue from eight unrelated marmosets across various ages was evaluated and compared to human postmortem AD tissue. Microtubule-associated protein tau ( MAPT ) mRNA expression and splicing were confirmed by RT-PCR. Tau isoforms in the marmoset brain were examined by western blot, mass spectrometry, immunofluorescence, and immunohistochemical staining. Synaptic Tau expression was analyzed from crude synaptosome extractions.

RESULTS

3R and 4R Tau isoforms are expressed in marmoset brains at both transcript and protein levels across ages. Results from western blot analysis were confirmed by mass spectrometry, which revealed that Tau peptides in marmoset corresponded to the 3R and 4R peptides in the human AD brain. 3R Tau was primarily enriched in neonate brains, and 4R enhanced in adult and aged brains. Tau was widely distributed in neurons with localization in the soma and synaptic regions. Phosphorylation residues were observed on Thr-181, Thr-217, and Thr-231, Ser202/Thr205, Ser396/Ser404. Paired helical filament (PHF)-like aggregates were also detected in aged marmosets.

DISCUSSION

Our results confirm the expression of both 3R and 4R Tau isoforms and important phosphorylation residues in the marmoset brain. These data emphasize the significance of marmosets with natural expression of AD-related hallmarks as important translational models for the study of AD.

Comparison of the Clinical Outcomes Between Early and Delayed Transplantation After SARS-CoV-2 Infection

Our study analyzed 95 solid organ transplant (SOT) and 78 hematopoietic stem cell transplant (HSCT) recipients with prior coronavirus disease 2019 (COVID-19). Patients who underwent transplantation within 30 days of COVID-19 infection comprised the early group, and those who underwent transplantation post-30 days of COVID-19 infection comprised the delayed group. In the early transplantation group, no patient, whether undergoing SOT and HSCT, experienced COVID-19-associated complications. In the delayed transplantation group, one patient each from SOT and HSCT experienced COVID-19-associated complications. Additionally, among early SOT and HSCT recipients, two and six patients underwent transplantation within seven days of COVID-19 diagnosis, respectively. However, no significant differences were observed in the clinical outcomes of these patients compared to those in other patients. Early transplantation following severe acute respiratory syndrome coronavirus 2 infection can be performed without increased risk of COVID-19-associated complications. Therefore, transplantation needs not be delayed by COVID-19 infection.

Clinical safety of remdesivir therapy in COVID-19 patients with renal insufficiency

Though remdesivir benefits COVID-19 patients, its use in those with renal dysfunction is currently limited due to concerns about possible toxic effects of accumulated sulfobutylether-β-cyclodextrin (SBECD) on liver and kidney. We examined renal and hepatic function for a month in renally-impaired COVID-19 patients who were treated or not treated with remdesivir to assess the safety of the drug. A retrospective study was performed in adult COVID-19 patients with glomerular filtration rates of <30 ml/min/1.73 m2 at admission to a tertiary care hospital between November 2020 and March 2022. Data on serum creatinine and liver chemistry were collected serially. A total of 101 patients with impaired renal function were analyzed, comprising 64 remdesivir-treated patients and 37 who did not receive any antiviral agent. Although remdesivir-treated patients were more likely to be infected with the Omicron variant (79.7% vs. 48.6%), baseline characteristics did not differ significantly between the two groups. Among patients who initially did not require dialysis, 18.4% (7/38) of remdesivir-treated patients developed acute kidney injury (AKI) at days 4-6, compared with 51.7% (15/29) of non-remdesivir-treated patients. Liver injury severity worsened in 3.1% (2/64) of remdesivir-treated patients and 5.4% (2/37) of non-remdesivir-treated patients at days 4-6. In addition, there was no significant increase in AKI and liver injury over time in remdesivir-treated patients, and there were no cases of discontinuation of remdesivir due to adverse reactions. Concerns regarding the safety of SBECD should not lead to hasty withholding of remdesivir treatment in renally-impaired COVID-19 patients.

The origin of sequence type 72 community-associated methicillin-resistant Staphylococcus aureus (MRSA) and fusidic acid (FA) resistant sequence type 5 MRSA: Analysis of FA resistance and spa type in a single center in South Korea

INTRODUCTION

We investigated the prevalence of fusidic acid (FA) resistance in MSSA and MRSA stratified by sequence (ST) and spa types, and determined the prevalence of FA resistance mechanisms.

METHODS

From August 2014 to April 2020, S. aureus blood isolates were collected in Asan Medical Center, Seoul, South Korea. Antimicrobial susceptibility tests were performed using broth microdilution and interpreted according to EUCAST's FA criteria. We performed spa typing for fusA mutation presence and acquired FA resistance determinants (fusB, fusC, and fusD) by PCR.

RESULTS

Of the 590 MRSA isolates, 372 were FA resistant, and among 425 MSSA isolates, 136 were resistant. Of the 380 ST5-MRSA isolates, 350 were FA resistant, whereas only 1 of 14 ST5-MSSA isolates was FA resistant. Conversely, of the 163 ST72-MRSA isolates, only 8 were resistant, whereas 37 of 42 ST72-MSSA were resistant. The fusA mutation (80%) was the most common determinant. The one FA resistant ST5-MSSA isolate belonged to the t2460 spa type, the most common spa type (24 of 35 isolates) of FA resistant ST5-MRSA. In addition, t324 and t148, which are minor spa types of ST72-MSSA, were susceptible to FA, in contrast to other ST72-MSSA spa types, and the major spa type of ST72-MRSA (110 of 163 isolates).

CONCLUSIONS

FA resistance was common in ST5-MRSA and ST72-MSSA, and rare in ST5-MSSA and ST72-MRSA. Our findings suggest that minor clones of ST5-MSSA isolates, with the fusA mutation and minor clones of ST72-MSSA susceptible to FA, may have evolved to harbor the mecA gene.

Comparative Analysis of CT Findings and Clinical Outcomes in Adult Patients With Disseminated and Localized Pulmonary Nocardiosis

BACKGROUND

Pulmonary nocardiosis is a rare opportunistic infection with occasional systemic dissemination. This study aimed to investigate the computed tomography (CT) findings and prognosis of pulmonary nocardiosis associated with dissemination.

METHODS

We conducted a retrospective analysis of patients diagnosed with pulmonary nocardiosis between March 2001 and September 2023. We reviewed the chest CT findings and categorized them based on the dominant CT findings as consolidation, nodules and/or masses, consolidation with multiple nodules, and nodular bronchiectasis. We compared chest CT findings between localized and disseminated pulmonary nocardiosis and identified significant prognostic factors associated with 12-month mortality using multivariate Cox regression analysis.

RESULTS

Pulmonary nocardiosis was diagnosed in 75 patients, of whom 14 (18.7%) had dissemination, including involvement of the brain in 9 (64.3%) cases, soft tissue in 3 (21.4%) cases and positive blood cultures in 3 (21.4%) cases. Disseminated pulmonary nocardiosis showed a higher frequency of cavitation (64.3% vs. 32.8%, P = 0.029) and pleural effusion (64.3% vs. 29.5%, P = 0.014) compared to localized infection. The 12-month mortality rate was 25.3%. The presence of dissemination was not a significant prognostic factor (hazard ratio [HR], 0.80; confidence interval [CI], 0.23-2.75; P = 0.724). Malignancy (HR, 9.73; CI, 2.32-40.72; P = 0.002), use of steroid medication (HR, 3.72; CI, 1.33-10.38; P = 0.012), and a CT pattern of consolidation with multiple nodules (HR, 4.99; CI, 1.41-17.70; P = 0.013) were associated with higher mortality rates.

CONCLUSION

Pulmonary nocardiosis with dissemination showed more frequent cavitation and pleural effusion compared to cases without dissemination, but dissemination alone did not affect the mortality rate of pulmonary nocardiosis.

Epidemiology and Disease Burden of Respiratory Syncytial Virus Infection in Adults

Respiratory syncytial virus (RSV) constitutes a significant cause of respiratory illness and mortality among older adults, a demographic that is expanding with considerable impact on healthcare systems worldwide. The actual burden of RSV in this population may still be underestimated, owing to factors such as low awareness and suboptimal diagnostic sensitivity in adults, the lack of robust RSV surveillance systems, and the infrequent use of diagnostic testing. Recent advancements in respiratory virus detection have spurred further exploration into appropriate preventive and therapeutic strategies. The recent approval of two vaccines highlights the critical need for the precise estimation of the RSV disease burden to optimize the effectiveness and cost-efficiency of immunization programs. This narrative review aimed to summarize the existing knowledge of the RSV burden in adults with a particular focus on older adults, incorporating data from Korea. Overall, current estimates indicate that the annual RSV attack rate in the general adult population ranges from 1 - 7%, increasing to approximately 4 - 10% among elderly and high-risk groups. The in-hospital mortality rate can be estimated to be around 7 - 10%, rising up to 40% among intensive care unit-admitted patients. To elucidate RSV's disease burden, further continuing research, including population-based studies, is necessary.

Noninvasive focal transgene delivery with viral neuronal tracers in the marmoset monkey

We establish a reliable method for selectively delivering adeno-associated viral vectors (AAVs) across the blood-brain barrier (BBB) in the marmoset without the need for neurosurgical injection. We focally perturbed the BBB (∼1 × 2 mm) in area 8aD of the frontal cortex in four adult marmoset monkeys using low-intensity transcranial focused ultrasound aided by microbubbles. Within an hour of opening the BBB, either AAV2 or AAV9 was delivered systemically via tail-vein injection. In all four marmosets, fluorescence-encoded neurons were observed at the site of BBB perturbation, with AAV2 showing a sparse distribution of transduced neurons when compared to AAV9. The results are compared to direct intracortical injections of anterograde tracers into area 8aD and similar (albeit sparser) long-range connectivity was observed. With evidence of transduced neurons specific to the region of BBB opening as well as long-distance tracing, we establish a framework for focal noninvasive transgene delivery to the marmoset brain.

Transcriptome dataset of two Pistacia species: Pistacia chinensis and Pistacia weinmannifolia

Pistacia chinensis and Pistacia weinmannifolia are small trees and are distributed in East Asia, in particular China. The data on P. chinensis presented in this article is associated with the research article, "DOI: 10.5010/JPB.2019.46.4.274" [1]. Both P. chinensis and P. weinmannifolia have long been used as ethnobotanical plants to treat various illnesses, including dysentery, inflammatory swelling, rheumatism, liver diseases, influenza, lung cancer, etc. Many studies have been carried out to delve into the pharmaceutical properties of these Pistacia species using plant extracts, but genomic studies are very rarely performed to date. To enrich the genetic information of these two species, RNA sequencing was conducted using a pair-end Illumina HiSeq2500 sequencing system, resulting in 2.6 G of raw data from P. chinensis (Accession no: SRR10136265) and 2.7 G bases from P. weinmannifolia (Accession no: SRR10136264). Transcriptome shotgun assembly using three different assembly tools generated a total of 18,524 non-redundant contigs (N50, 1104 bp) from P. chinensis and 18,956 from P. weinmannifolia (N50, 1137 bp). The data is accessible at NCBI BioProject: PRJNA566127. These data would be crucial for the identification of genes associated with the compounds exerting pharmaceutical properties and also for molecular marker development.

Direct interhemispheric cortical communication via thalamic commissures: a new white matter pathway in the primate brain

Cortical neurons of eutherian mammals project to the contralateral hemisphere, crossing the midline primarily via the corpus callosum and the anterior, posterior, and hippocampal commissures. We recently reported and named the thalamic commissures (TCs) as an additional interhemispheric axonal fiber pathway connecting the cortex to the contralateral thalamus in the rodent brain. Here, we demonstrate that TCs also exist in primates and characterize the connectivity of these pathways with high-resolution diffusion-weighted MRI, viral axonal tracing, and fMRI. We present evidence of TCs in both New World (Callithrix jacchus and Cebus apella) and Old World primates (Macaca mulatta). Further, like rodents, we show that the TCs in primates develop during the embryonic period, forming anatomical and functionally active connections of the cortex with the contralateral thalamus. We also searched for TCs in the human brain, showing their presence in humans with brain malformations, although we could not identify TCs in healthy subjects. These results pose the TCs as a vital fiber pathway in the primate brain, allowing for more robust interhemispheric connectivity and synchrony and serving as an alternative commissural route in developmental brain malformations.

CT findings of inferior vena cava trauma according to the level of injury: a retrospective analysis of 19 cases in a single trauma centre

AIM

To analyse the clinicoradiological characteristics of traumatic inferior vena cava (IVC) injury level on preoperative computed tomography (CT).

MATERIALS AND METHODS

This retrospective study evaluated patients from a single trauma centre treated for traumatic IVC injury between January 2014 and January 2021. Data on demographics, mechanism of injury, Injury Severity Score, radiological findings on CT and angiography, IVC injury level in surgical findings, complications, and clinical outcomes were collected.

RESULTS

During the 8-year study period, 36 patients presented with traumatic IVC injury: 19 underwent preoperative CT with 17 (89%) blunt and two (11%) penetrating injuries. The most common primary CT sign was contour abnormality (53%, n=10), followed by intraluminal flap and active extravasation (21%, n=4). Among the secondary signs, hepatic laceration (53%, n=10) and retroperitoneal haemorrhage (53%, n=10) were the most common. Frequencies of primary and secondary signs were higher in the infrarenal and suprarenal than in the retrohepatic vena cava injuries. Diagnostic capability of preoperative CT for IVC injury differed according to the IVC level. The detection rate was the highest for an infrarenal vena cava injury at 100% (n=4), followed by that for a suprarenal, suprahepatic, and retrohepatic vena cava injuries at 75% (n=3), 43% (n=3), and 25% (n=1), respectively.

CONCLUSION

CT findings of traumatic IVC injuries may vary depending on the mechanism and anatomical site of injury. Familiarity with IVC injury imaging features may help in diagnosis and surgical treatment planning.

College students' preferences for tobacco treatment: a discrete choice experiment

The purpose of this study was to elicit preferences for the 'format' and 'content' of tobacco treatment among college student smokers, using an online discrete choice experiment (DCE) survey. A DCE survey, supplemented with a think-aloud method, was conducted among 54 college students who smoked combustible cigarettes and/or e-cigarettes. Conditional logistic regression models were constructed to determine optimal profiles of treatment. Cutting down nicotine rather than quitting 'cold turkey' (P < 0.001) and two-way communication (P < 0.001) were viewed as the most critical attributes for the intervention 'format'; changing behaviors rather than social groups/peers (P < 0.001) and autonomy (P < 0.001) were viewed as the most critical attributes for the intervention 'content'. Some preferences varied based on smoking subgroups. Combustible cigarette users preferred interventions with a longer time commitment (P < 0.05) and without nicotine replacement therapies (NRTs) (P < 0.001). Think-aloud data supported the DCE findings and further revealed a strong desire for cutting down nicotine and keeping social groups/peers and misconceptions regarding NRTs. Our study findings can guide tobacco treatment tailored to college students. These treatments should be tailored to specific smoker subgroups.

Effect of dexamethasone dose on outcomes in acute COVID-19 disease: A systematic review and meta-analysis

INTRODUCTION

The impact of different doses of dexamethasone on outcomes from acute COVID-19 pneumonia is unknown.

METHODS

We performed a systematic review and meta-analysis of randomised control trials comparing different doses of dexamethasone in adult patients with COVID-19. High dose dexamethasone treatment was defined as 12-24 mg daily, whereas low-dose treatment was 6-8 mg daily. Primary outcome was 28-day mortality.

RESULTS

Eight trials including 3469 patients were identified, with 1775 patients receiving high dose dexamethasone. There was no difference in mortality between patients receiving high dose or low-dose dexamethasone (22.0% vs. 20.2%; odds ratio 1.20 [95% confidence interval 0.86-1.67]; p = 0.29; I2 = 63%; TSA-adjusted CI [0.31-4.66]; very low QoE). Meta-regression did not demonstrate a dose-dependent effect of steroids on mortality. High dose dexamethasone was associated with an increased risk of hyperglycaemia (23.6% vs. 17.2%; 1.51 [1.19-1.92]; p = 0.0008; I2 = 0%; TSA-adjusted CI [0.90-2.54]; low QoE) but not secondary infections (14.3% vs. 15.0%; 0.87 [0.56-1.37]; p = 0.56; I2 = 72%; very low QoE). Risk of bias was low for seven of the eight studies.

CONCLUSIONS

The mortality of patients with acute COVID-19 receiving high-dose dexamethasone is similar to patients receiving low-dose dexamethasone, although high-dose dexamethasone is associated with an increased risk of hyperglycaemia.

Clinical impact of metformin exposure during Staphylococcus aureus bacteremia in patients with diabetes mellitus

PURPOSE

Increasing evidence has suggested that metformin may play positive roles in a wide range of infectious diseases. This study aimed to investigate the clinical impact of metformin exposure during Staphylococcus aureus bacteremia (SAB) in patients with diabetes.

METHODS

A 3-year observational cohort study of 452 patients (aged ≥ 16 years) with SAB was performed at a tertiary care hospital. Metformin exposure was defined as receiving metformin during SAB, regardless of metformin use before the onset of bacteremia.

RESULTS

Of 452 patients, 51 (11.3%) were classified in Group A (diabetes with metformin exposure), 115 (25.4%) in Group B (diabetes without metformin exposure), and 286 (63.3%) in Group C (no diabetes). The 30-day mortality rate in Group A was significantly lower than that in Group B (3.9% [2/51] versus 14.8% [17/115]; p = 0.04) and lower than that in Group C (3.9% [2/51] versus 17.1% [49/286]; p = 0.02). The mortality rates did not differ between Group B and Group C (14.8% [17/115] versus 17.1% [49/286]; p = 0.57). The rates of persistent and recurrent bacteremia were comparable among the three groups. Multivariate analysis indicated that metformin exposure was significantly associated with reduced mortality (adjusted odds ratio, 0.20; 95% confidence interval, 0.04-0.88; p = 0.03).

CONCLUSIONS

Metformin exposure during SAB appears to be an independent predictor of survival in patients with diabetes.

Routine ophthalmologic examination in Klebsiella pneumoniae bacteremia is not necessary: incidence of and risk factors for ocular involvement

Klebsiella pneumoniae bacteremia is known to present a virulent clinical course, including multiple metastatic infections, which is not uncommon in Asia. However, there are limited data on the incidence and risk factors for ocular involvement in K. pneumoniae bacteremia. We retrospectively reviewed the medical records of all patients with K. pneumoniae bacteremia who underwent ophthalmologic examination in a tertiary center in Seoul, Korea, from February 2012 to December 2020. Two retinal specialists reviewed the findings of the ophthalmologic examinations and classified them as endophthalmitis, chorioretinitis, and no ocular involvement. Of 689 patients, 56 [8.1%; 95% confidence interval (CI) 6.2-10.4] had ocular involvement, and 9 (1.3%; 95% CI 0.6-2.5) were diagnosed with endophthalmitis. Of 47 patients with chorioretinitis, 45 (95.7%) improved with systemic antibiotic therapy alone. Community-onset bacteremia (100% vs 62.1% vs 57.4%, P = 0.04), cryptogenic liver abscess (55.6% vs 11.8% vs 8.5%, P = 0.003), and metastatic infection (66.7% vs 5.8% vs 10.6%, P < 0.001) were more common in endophthalmitis than in no ocular involvement or chorioretinitis. In the multivariable analysis, cryptogenic liver abscess [adjusted odds ratio (aOR), 6.63; 95% CI 1.44-35.20] and metastatic infection (aOR, 17.52; 95% CI 3.69-96.93) were independent risk factors for endophthalmitis. Endophthalmitis was not associated with 30-day mortality. Endophthalmitis is rare in Asian patients with K. pneumoniae bacteremia. Targeted ophthalmologic examination in those with cryptogenic liver abscess, metastatic infection, or ocular symptoms may be more appropriate than routine examination of all patients.

Clinical Characteristics of and Risk Factors for Subsequent Carbapenemase-producing Enterobacterales (CPE) Bacteraemia in Rectal CPE Carriers

BACKGROUND

Due to high mortality and limited treatment options, the rise in carbapenemase-producing Enterobacterales (CPE) has become a major concern. This study aimed to evaluate the incidence and characteristics of subsequent CPE bacteraemia in rectal CPE carriers and investigate the risk factors for CPE bacteraemia compared with non-carbapenemase-producing (non-CP) Enterobacterales bacteraemia.

METHODS

A retrospective analysis was conducted on adult patients who were confirmed to have CPE colonisation by stool surveillance culture at a tertiary hospital from January 2018 to February 2022. All episodes of Enterobacterales bacteraemia up to 6 months after CPE colonisation were identified.

RESULTS

Of 1174 patients identified as rectal CPE carriers, 69 (5.8%; 95% CI 4.6-7.3%) experienced subsequent CPE bacteraemia during the 6 months after the diagnosis of CPE colonisation. Colonisation by a Klebsiella pneumoniae carbapenemase (KPC) producer (or CP-K. pneumoniae), colonisation by multiple CPE species, chronic kidney disease and haematological malignancy were independently associated with CPE bacteraemia in CPE carriers. When CPE carriers developed Enterobacterales bacteraemia, the causative agent was more frequently non-CP Enterobacterales than CPE (63.6% vs. 36.4%). Among these patients, colonisation with a KPC producer, CPE colonisation at multiple sites, shorter duration from colonisation to bacteraemia (< 30 days) and recent intraabdominal surgery were independent risk factors for CPE bacteraemia rather than non-CP Enterobacterales bacteraemia.

CONCLUSIONS

In CPE carriers, non-CP Enterobacterales were more often responsible for bacteraemia than CPE. Empirical antibiotic therapy for CPE should be considered when sepsis is suspected in a CPE carrier with risk factors for CPE bacteraemia.

Molecular Characteristics and Prevalence of Rifampin Resistance in Staphylococcus aureus Isolates from Patients with Bacteremia in South Korea

Rifampin resistance (RIF-R) in Staphylococcus aureus (S. aureus) with rpoB mutations as one of its resistance mechanisms has raised concern about clinical treatment and infection prevention strategies. Data on the prevalence and molecular epidemiology of RIF-R S. aureus blood isolates in South Korea are scarce. We used broth microdilution to investigate RIF-R prevalence and analyzed the rpoB gene mutation in 1615 S. aureus blood isolates (772 methicillin-susceptible and 843 methicillin-resistant S. aureus (MRSA)) from patients with bacteremia, between 2008 and 2017. RIF-R prevalence and antimicrobial susceptibility were determined. Multilocus sequence typing was used to characterize the isolate's molecular epidemiology; Staphylococcus protein A (spa), staphylococcal cassette chromosome mec (SCCmec), and rpoB gene mutations were detected by PCR. Among 52 RIF-R MRSA isolates out of 57 RIF-R S. aureus blood isolates (57/1615, 0.4%; 5 methicillin-susceptible and 52 MRSA), ST5 (44/52, 84.6%), SCCmec IIb (40/52, 76.9%), and spa t2460 (27/52, 51.9%) were predominant. rpoB gene mutations with amino acid substitutions showed that A477D (17/48, 35.4%) frequently conferred high-level RIF resistance (MIC > 128 mg/L), followed by H481Y (4/48, 8.3%). RIF-R S. aureus blood isolates in South Korea have unique molecular characteristics and are closely associated with rpoB gene mutations. RIF-R surveillance through S. aureus-blood isolate epidemiology could enable effective therapeutic management.

The Role of Local Prostate and Metastasis-Directed Radiotherapy in the Treatment of Oligometastatic Prostate Cancer

PURPOSE/OBJECTIVE(S)

The local ablative therapy for oligometastatic disease (OMD) has the potential to delay further metastases and improve survival. However, it has not been fully elucidated how prostate primary radiotherapy (PPR) and metastasis-directed radiotherapy (MDR) affect prognosis in each different OMD scenario. Herein, we tried to provide efficacy and future perspectives for MDR in oligometastatic prostate cancer.

MATERIALS/METHODS

Patients diagnosed with prostate cancer between 2010 and 2019 and treated for OMD (≤5 active lesions), which occurred synchronously or metachronously, were included. All patients received MDR at all detected lesions (OMDRT). OMDRT which was performed as soon as OMD was detected was classified as early, and OMDRT for progressions after hormone therapy was classified as late. The primary endpoint was survival after OMDRT, and timing of progression after RT was also analyzed.

RESULTS

A total of 82 patients with oligometastatic prostate cancer received OMDRT. Among 36 patients with synchronous OMD, 58% received PPR at diagnosis, and 64% received early OMDRT. Among 46 patients with metachronous OMD, 80% received early OMDRT, and 28 received sequential OMDRT for repetitive OMD events. With a median follow-up of 32 months after OMDRT, 54 patients experienced progression and 5-year survival was 78%. Survival was highest in patients with synchronous OMD and early RT (5-year 86%), and 5-year survival of patients with metachronous OMD and early RT was significantly higher than those with late RT (78% vs. 44%, p = 0.003). Survival of patients with synchronous OMD and PPR was significantly higher than those without PPR or with metachronous OMD (5-year 90% vs. 66%, p = 0.030), by delaying progressions (17.9 vs. 7.0 months, p = 0.005).

CONCLUSION

Survival gain could be achieved through OMDRT in oligometastatic prostate cancer, especially in synchronous OMD status. Also, it was possible to improve the prognosis further when OMDRT was performed early and with PPR.

Patient-Specific Deep Learning Model for Clinical Target Volume Delineation on Daily CBCT of Breast Cancer Patients based on Intentional Deep Overfit Learning (IDOL) Framework

PURPOSE/OBJECTIVE(S)

Increasingly complex target volumes and the use of modern irradiation techniques emphasize the importance of daily image guidance more than ever. Significant progress has been made in adjuvant breast cancer radiotherapy (RT) and the need for optimized image guidance is growing. Furthermore, the position of the breast during RT after breast-conserving surgery is highly variable than expected. In this context, cone beam computed tomography (CBCT) is a very effective tool enabling prompt and accurate adaptive radiation therapy (ART). In this study, we aim to develop a deep learning (DL)-based algorithm to segment clinical target volume (CTV) from daily CBCT scans. Also, we validate the optimization of further learning when applying the Intentional Deep Overfit Learning (IDOL) framework.

MATERIALS/METHODS

A total of 240 different CBCT scans obtained from 100 breast cancer patients were used for this study. CTV was defined as whole breast plus margin in all patients. The workflow consists of two training stages: (1) training a novel 'generalized' DL model (Swin_UNETR) to identify and delineate breast CTV on CBCT scans using 90 breast cancer patient cases (2) applying an 'intentional overfitting' to the 'generalized' DL model to generate a 'patient-specific' model using the remaining 10 breast cancer patients. In this study, for the intentionally overfitting stage, we additionally trained with CBCT scans from the patient's 1st fraction to the 14th fractions cases. The results of the proposed method were compared quantitatively with the expert's contours on 1st-15th fractions CBCT scans using Dice Similarity Coefficient (DSC).

RESULTS

The average DSC between the 'generalized' DL model-based breast CTV contours and reference contours for the patient's 15th fraction was 0.9672. When implementing the IDOL framework with the CBCT scan obtained during the patient's 1st treatment, the average DSC was improved to 0.9809. When additional CBCT scans taken during each of the 1st to 6th fractions were used for training, the average DSC could be most effectively raised to 0.9835. The p-value comparison between the 'generalized' DL model and the 1st fraction was found to be 3.62E-04, while the comparison with the 6th fractions resulted in a p-value of 8.36E-05. The average time required for IDOL training using one CBCT scan and six CBCT scans was 107 seconds and 127 seconds, respectively.

CONCLUSION

In this study, we developed a patient-specific DL-based training algorithm to segment CTV in CBCT scans for breast cancer patients. The performance improvement was relatively significant and was confirmed that using continual DL with additional CBCT scans, which are taken every day, can be more accurate and efficient than drawing breast CTV using a general model. Our novel patient-specific model can be effectively applied to various ARTs by not only reducing labor and time but also increasing accuracy.

Comparison of Early Outcomes of Stereotactic Accelerated Partial Breast Irradiation vs. Volumetric Modulated Arc Therapy-Based FAST-FORWARD Whole Breast Irradiation for Breast Cancer

PURPOSE/OBJECTIVE(S)

Despite evidence supporting APBI from 8 published prospective randomized trials enrolling over 10,000 women, the uptake of APBI in clinical practice is surprisingly low. This is being exacerbated by a new, convenient, and safe shortened WBI schedule. Here, we report the dosimetric and early outcome analyses of the first >1000 patients treated at our institution since the first adoption of stereotactic APBI and the ultra-hypofractionated WBI regimen.

MATERIALS/METHODS

From 2016 to 2022, 801 women with breast cancers in the suitable or cautionary categories according to the ASTRO APBI consensus panel guidelines, received 30 Gy in 5 fractions (92%) either using a robotic stereotactic radiation system (83%) or stereotactic volumetric-based arc therapy (VMAT, 17%). Between 2020 and 2022, 468 women, who were not candidates for APBI and not undergoing any regional irradiation received 26 Gy in 5 fractions using VMAT to the whole breast with the addition of cardiac sparing technique in left-sided breast cancer patients. Tumor bed boosts were delivered in 99% of FF-WBI patients. We evaluated dose-volume histogram parameters for target volumes and organs-at-risk and radiation-related toxicities during RT or within 6 months after the end of RT.

RESULTS

Target volume coverage was acceptable in both groups, with mean 96% of the target volumes receiving 95% of the prescribed doses and 0 cm3 within target volumes exceeding 105% of the prescribed doses. S-APBI resulted in small, but statistically significant, reductions in the radiation dose delivered to the ipsilateral breast, contralateral breast, lungs, heart, and coronary artery compared with FF-WBI. Comparing WBI to APBI, the mean contralateral breast dose, ipsilateral lung V20 Gy, mean contralateral lung dose, and mean heart dose, were reduced by 89%, 78%, 73%, and 29%, respectively. With median follow-up periods of 32 months for s-APBI and 19 months for FF-WBI, acute toxicity was assessable in all patients. The risks of any grade acute toxicity were 21% for s-APBI and 25% for FF-WBI (p = .117). Among them, grade 2 rates were 1.3% in both groups and no severe toxicity has been reported.

CONCLUSION

We found s-APBI and VMAT-based FF WBI were associated with favorable dosimetric and acute toxicity profiles. However, considering significantly less irradiated volume in the breast, lungs, and heart, APBI with advanced available technique options should be considered over any WBI-based approach for patients at low risk for local recurrence.

Association of Single Nucleotide Polymorphisms in Transforming Growth Factor-β1 Pathway and Risk of Radiation Pneumonitis in Lung Cancer Patients Treated with Thoracic Radiation Therapy

PURPOSE/OBJECTIVE(S)

Several clinical and dosimetric parameters are known to be associated with radiation-induced lung toxicity, including radiation pneumonitis (RP). Also, single nucleotide polymorphisms (SNPs) of genes in TGF-β1 pathway have a notable association with the RP. However, studies on the predictive value of SNPs for RP are still limited. Herein, we tried to develop a novel integrated predictive model for severe RP in lung cancer patients.

MATERIALS/METHODS

A total of 59 patients who were treated with definitive or preoperative radiotherapy for primary lung cancer and had DNA samples were included. Potentially functional and tagging SNPs of TGF-β1 (rs1800469, rs1800471, rs1982073, and rs11466345), BMP2 (rs235768, rs3178250, rs1979855, and rs170986), and BMP4 (rs17563, rs4898820, and rs762642) were genotyped. Logistic regression was performed to build severe (grade ≥2) RP prediction models, and best subset selection algorithm with L0 and L2 regulations was used for variable selection. Only clinical/dosimetric variables were evaluated in model 1, and those variables as well as SNPs were included in model 2. Using beta coefficient obtained by the logistic regression, a scoring system was also developed.

RESULTS

With median follow-up of 39.7 months, severe RP occurred in 20.3% of patients. In model 1, age (>66) and PTV volume (≥300 cc) were significant factors (p = 0.016, OR 8.820 [95% CI, 1.730-63.800]; and p = 0.024, OR 7.440 [95% CI, 1.460-52.100], respectively). In model 2, the above two factors (p = 0.010, OR 16.200 [95% CI, 2.440-187.000] and p = 0.025, OR 10.100 [95% CI, 1.610-105.000]) and the AG/GG genotype in BMP2 rs1979855 were significant factors (p = 0.031, OR 7.260 [95% CI, 1.380-59.100]). The AUC was significantly higher in model 2 than in model 1 (0.822 vs. 0.741, p = 0.029). According to developed scoring system, patients with a score >2.8 are more likely to experience severe RP (AUC 0.829).

CONCLUSION

BMP2 rs1979855 could serve as a reliable biomarker for predicting RP while significantly improving predictive power compared to when only clinical factors were used.

Protracted course of SARS-CoV-2 pneumonia in moderately to severely immunocompromised patients

There have been few studies comparing the clinical characteristics and outcomes of SARS-CoV-2 pneumonia in individuals with and without moderately to severely immunocompromised conditions. We reviewed adult patients with SARS-CoV-2 infection who had radiologic evidence of pneumonia at a tertiary hospital in Seoul, South Korea, from February 2020 to April 2022. Moderately to severely immunocompromised status was defined as medical conditions or treatments that resulted in increased risk of severe COVID-19 and weakened immune response to COVID-19 vaccine as recommended by Centers for Disease Control and Prevention. The time to pneumonia development was defined as the time from symptom onset to the time when radiologic evidence of pneumonia was obtained. Viral clearance was defined as a Ct value > 30. COVID-19-related death was defined as 90-day death following imaging-confirmed pneumonia without any other plausible cause of death. A total of 467 patients with SARS-CoV-2 pneumonia were analyzed. Of these, 102 (22%) were moderately to severely immunocompromised. The median (IQR) time to pneumonia development was significantly longer in moderately to severely immunocompromised patients (9.5 [6-14] days) than the comparator (6 [3-8] days), p < 0.001), as was the median time to viral clearance (21 versus 12 days, p < 0.001). Moderately to severely immunocompromised status (aOR, 18.39; 95% CI, 5.80-58.30; p < 0.001) was independently associated with COVID-19-related death. Patients with moderately to severely immunocompromised conditions are likely to experience a more protracted course of SARS-CoV-2 pneumonia and a worse outcome than those without these conditions.

Distribution and Failure Patterns of Primary Central Nervous System Lymphoma Related to Hippocampus

PURPOSE/OBJECTIVE(S)

Hippocampus (HC) injury by conventional whole brain radiotherapy (C-WBRT) contributes to the neurocognitive decline in primary central nervous system lymphoma (PCNSL). Hippocampal avoidance (HA-WBRT) could minimize neurocognitive impairment by reducing the radiation dose to HC. However, its feasibility in PCNSL has not been examined regarding the incidence of HC involvement and failures. In this retrospective study, we assessed the risk of hippocampal area involvement at diagnosis and after treatments in PCNSL patients.

MATERIALS/METHODS

We identified 278 immunocompetent PCNSL patients diagnosed between 2000 and 2020. After high dose methotrexate-based induction chemotherapy, patients were observed or given consolidation therapy including RT, cytarabine alone, or autologous stem cell transplantation (ASCT). HC was contoured on T1 MRI image and expanded with a 5mm margin, generating hippocampal avoidance region (HAR). The extent of initial and recurrent lesions was evaluated using pre-induction and post-consolidation T1 contrast-enhanced MRI images. HC failure was defined as recurrence or progression at HAR and those who progressed after induction were excluded. The median follow up was 38.7 months (3.1-239.4).

RESULTS

Of 278 patients diagnosed with PCNSL, 39.9% of them had initial lesions at HAR (Figure 1a). After induction therapy, 212 evaluable patients received following treatments: RT (n = 145, 68.4%) consisting of C-WBRT (n = 114), HA-WBRT (n = 23), and focal RT (n = 8), observation (n = 38, 17.9%), cytarabine only (24, 11.3%), and ASCT (n = 5, 2.4%). Intracranial failures occurred in 47.6% (n = 101) of patients, with 33.7% (n = 34) of them in HAR (Figure 1b). The multivariate analysis identified multifocal disease (HR 3.86, 95% CI 1.15-9.73, p = 0.004) as the only factor associated with the risk of HC failure. Those with unifocal lesion outside HAR showed the lowest HC failure rate, 7.0%, while the highest HC failure rate, 25.4% was observed in the subgroup with multifocal disease within HAR at diagnosis (Figure 2a). In the lowest risk group (unifocal lesion outside HAR, n = 66), C-WBRT was not significantly associated with HC failure (HR 0.57, CI 0.09-3.33, P = .572, Figure 2b) or intracranial failure (HR 0.88, CI 0.40-1.91, P = .748).

CONCLUSION

Our data suggest the HA-WBRT could be explored in patients whose lesion is unifocal and located outside HAR. For patients without initial HAR involvement, hippocampal including WBRT did not significantly change HC failure. Further prospective study will be warranted to assess the feasibility of HA-WBRT in the subgroup with low risk of HC failure.

A Photograph-Based Visualization and Prediction Framework for Radiation-Induced Dermatitis

PURPOSE/OBJECTIVE(S)

This study aimed to suggest a photograph-based prediction system for acute radiation-induced dermatitis (RID), which can be applied to notify patients about the risk of the development of skin discomfort during radiotherapy.

MATERIALS/METHODS

The proposed system compared the spatial dose distribution with the RID region using the following methods. Skin photographs of patients were taken using an RGB-depth camera to acquire the shape information of RID. The skin surface data measured from the camera was registered with the shape of the external body contour using an iterative closest point algorithm. Spatial dose distribution of skin was extracted from the external body contour to a depth of 2 mm and projected onto the plane of the skin photograph using a transformation matrix for skin depth data. To compare the spatial distribution of skin dose with the shape of RID, the region of RID in patients' skin was delineated on photographs into three toxicity symptoms referring to the CTCAE criteria grade 1 (skin redness), grade 2 (dry desquamation), and grade 3 (moist desquamation). The degree of overlap between the shape of each RID and skin dose distribution was evaluated using the dice similarity coefficient (DSC). Threshold doses for predicting RID occurrence were estimated by skin isodose lines with the highest DSC. The developed system was validated using data from 19 patients who received volumetric modulated arc therapy for head-neck cancer at a single institution.

RESULTS

Threshold doses for RID grades 1, 2, and 3 were estimated using 18, 18, and 2 individual RID labels delineated on skin photographs, respectively. Isodose lines with the highest DSC for RID grades 1, 2, and 3 were calculated as 26.0 Gy, 36.5 Gy, and 54.0 Gy, respectively. A strong overlap (average DSC > 0.6) was observed between isodose skin lines and the shape of RID labels in all RID grades.

CONCLUSION

Assessing the spatial information of skin dose can be helpful in predicting acute RID. The region of RID shows a strong similarity with the skin dose distribution in head-neck patients. Visualization of skin dose on the patient photograph is potent to patient education for preparing the cosmetic discomfort during radiotherapy, which may lead to the improvement of the patient satisfaction in treatment.

Clinical characteristics of COVID-19 rebound after nirmatrelvir-ritonavir or molnupiravir therapy: A prospective cohort study

The clinical characteristics of the rebound phenomenon after antiviral therapy in patients with Coronavirus disease-2019 (COVID-19) are largely unknown. There are few data comparing the rebound phenomenon after molnupiravir therapy to that after nirmatrelvir-ritonavir therapy. We investigated the incidence and risk factors associated with COVID-19 rebound after nirmatrelvir-ritonavir or molnupiravir therapy during the Omicron era. This prospective cohort study enrolled patients with mild-to-moderate COVID-19 who received nirmatrelvir-ritonavir or molnupiravir. We conducted weekly questionnaires of symptom scores from day 0 to day 28, with an additional day when patients experienced reappearing symptoms. We defined COVID-19 rebound as when patients experienced a 50% increase in symptom scores compared to the lowest symptom score between days 0 and 14. Among the 150 patients, 93 (62%) and 57 (38%) received nirmatrelvir-ritonavir therapy and molnupiravir, respectively. Of these, 11 patients (7.3%; 95% CI, 3.1-11.5) experienced COVID-19 rebound. The median duration from antiviral therapy to rebound was 12 days. Patients with clinical rebound had a higher symptom score at antiviral therapy initiation than those without (median, 5 vs 4; P = .02). There was no significant difference in the clinical rebounds associated with nirmatrelvir-ritonavir and molnupiravir therapy (5.4% vs 10.5%; P = .39). Approximately one-tenth of patients with mild-to-moderate COVID-19 who received antiviral therapy experienced rebound phenomena after treatment. Regardless of antiviral therapy type, high initial symptom scores were associated with a more frequent rebound phenomenon.

False positive Aspergillus galactomannan assay results caused by specific parenteral nutrition

In September 2022, the proportion of clinically false positive results with high index values for the galactomannan (GM) assay increased dramatically in our hospital and remained high until November 2022. We aimed to identify the possible causative agent that led to the dramatic increase in false positivity in GM assay. A case-control-control study was conducted, and patients admitted to two intensive care units between September and November 2022 were included. We defined each time point at which the GM assay was conducted in a patient as an episode and classified episodes into strong-positive (≥10.0 index; case), positive (control), and negative (<0.5 index; control) groups. We compared the medications administered in three groups and measured GM levels in relevant medications, including parenteral nutrition (PN). In total, 118 episodes in 33 patients were classified into three groups. There were 46 negative, 23 positive, and 49 strong-positive episodes, and there was a significant difference in the use of Winuf® PNs (P < .001) between the three groups. Forty episodes (82%) in the strong-positive group received Winuf®, compared with three (6.5%) in the negative group and one (4.3%) in the positive group (P < .001). All samples of Winuf® PNs used in the five patients whose GM results were repeatedly strong-positive were strongly positive for GM. False positivity in GM assay can be caused by the administration of specific PNs. A thorough investigation of prescribed medications should be considered when there is an abrupt increase in the proportion of strong-positive or positive GM results.

Causes of a Low Measles Seroprevalence among Young Healthcare Workers in Korea

BACKGROUND

Sporadic measles outbreaks have continued to occur in Korea, mainly in adults in their 20s and 30s, most notably in 2014 and 2019. We here evaluated the possible causes of a low seroprevalance of measles by testing young healthcare workers (HCWs).

MATERIALS AND METHODS

This study was conducted in a 2,743-bed tertiary-care hospital in Seoul between 2020 and 2021. We performed a measles antibody test (chemiluminescence immunoassay), measured the IgM/IgG index ratio, and conducted an avidity test at 1-month after Measles-Mumps-Rubella (MMR) vaccination in HCWs who had been seronegative for measles. Measles vaccination histories were obtained from the national vaccine registry.

RESULTS

Of the 3,173 HCWs newly employed in our hospital during the study period, 54 with a negative measles IgG at commencement were enrolled. Thirty six (67%) of these subjects were female, and the median age was 25 years (interquartile range [IQR]: 24 - 27). Fourty nine (91%) showed seroconversion at 1 month after the first vaccination. Of these individuals, 38 received both measles IgM and IgG test, and all had an IgM/IgG index <1. Of the 49 seroconverters, all HCWs showed a high avidity index. According to the national immunization registry, 45 (83%) received at least 2 doses of an MMR vaccination.

CONCLUSION

Secondary vaccine failure may underlie vaccine failure in young Korean adults. HCWs born after 1985 with a negative measles antibody may need only a single dose booster vaccination rather than a 2-dose vaccination regimen.

Respiratory fluoroquinolone monotherapy vs. β-lactam plus macrolide combination therapy for hospitalized adults with community-acquired pneumonia: A systematic review and meta-analysis of randomized controlled trials

INTRODUCTION

Guidelines recommend respiratory fluoroquinolone monotherapy or β-lactam plus macrolide combination therapy as first-line options for hospitalized adults with mild-to-moderate community-acquired pneumonia (CAP). Efficacy of these regimens has not been adequately evaluated.

METHODS

A systematic review of randomized controlled trials (RCTs) comparing respiratory fluoroquinolone monotherapy and β-lactam plus macrolide combination therapy in hospitalised adults with CAP was performed. A meta-analysis was performed using a random effects model. The primary outcome was clinical cure rate. Quality of evidence (QoE) was evaluated using GRADE methodology.

RESULTS

A total of 4140 participants in 18 RCTs were included. Levofloxacin (11 trials) or moxifloxacin (6 trials) were the predominant respiratory fluoroquinolones evaluated, and the β-lactam plus macrolide group used ceftriaxone plus a macrolide (10 trials), cefuroxime plus azithromycin (5 trials), and amoxicillin/clavulanate plus a macrolide (2 trials). Patients receiving respiratory fluoroquinolone monotherapy had a significantly higher clinical cure rate (86.5% vs. 81.5%; odds ratio [OR] 1.47; 95% confidence interval [95% CI: 1.17-1.83]; P = 0.0008; I2 = 0%; 17 RCTs; moderate QoE) and microbiological eradication rate (86.0% vs. 81.0%; OR 1.51 [95% CI: 1.00-2.26]; P = 0.05; I2 = 0%; 15 RCTs; moderate QoE) than patients receiving β-lactam plus macrolide combination therapy. All-cause mortality (7.2% vs. 7.7%; OR 0.88 [95% CI: 0.67-1.17]; I2 = 0%; low QoE) and adverse events (24.8% vs. 28.1%; OR 0.87 [95% CI: 0.69-1.09]; I2 = 0%; low QoE] were similar in the two groups.

CONCLUSION

Respiratory fluoroquinolone monotherapy demonstrated an advantage in clinical cure and microbiological eradication; however, it did not impact mortality.

Risk and Outcome of Infective Endocarditis in Streptococcal Bloodstream Infections according to Streptococcal Species

This study aimed to identify which streptococcal species are closely associated with infective endocarditis (IE) and to evaluate risk factors for mortality in patients with streptococcal IE. We performed a retrospective cohort study of all patients with streptococcal bloodstream infection (BSI) from January 2010 to June 2020 in a tertiary hospital in South Korea. We compared clinical and microbiological characteristics of streptococcal BSIs according to the diagnosis of IE. We performed multivariate analysis to evaluate the risk of IE according to streptococcal species and risk factors for mortality in streptococcal IE. A total of 2,737 patients were identified during the study period, and 174 (6.4%) were diagnosed with IE. The highest IE prevalence was in patients with Streptococcus mutans BSI (33% [9/27]) followed by S. sanguinis (31% [20/64]), S. gordonii (23% [5/22]), S. gallolyticus (16% [12/77]), and S. oralis (12% [14/115]). In multivariate analysis, previous IE, high-grade BSI, native valve disease, prosthetic valve, congenital heart disease, and community-onset BSI were independent risk factors for IE. After adjusting for these factors, S. sanguinis (adjusted OR [aOR], 7.75), S. mutans (aOR, 5.50), and S. gallolyticus (aOR, 2.57) were significantly associated with higher risk of IE, whereas S. pneumoniae (aOR, 0.23) and S. constellatus (aOR, 0.37) were associated with lower risk of IE. Age, hospital-acquired BSI, ischemic heart disease, and chronic kidney disease were independent risk factors for mortality in streptococcal IE. Our study points to significant differences in the prevalence of IE in streptococcal BSI according to species. IMPORTANCE Our study of risk of infective endocarditis in patients with streptococcal bloodstream infection demonstrated that Streptococcus sanguinis, S. mutans, and S. gallolyticus were significantly associated with higher risk of infective endocarditis. However, when we evaluated the performance of echocardiography in patients with streptococcal bloodstream infection, patients with S. mutans and S. gordonii bloodstream infection had a tendency of low performance in echocardiography. There are significant differences in the prevalence of infective endocarditis in streptococcal bloodstream infection according to species. Therefore, performing echocardiography in streptococcal bloodstream infection with a high prevalence of, and significant association with, infective endocarditis is desirable.

Noninvasive disruption of the blood-brain barrier in the marmoset monkey

The common marmoset monkey (Callithrix jacchus) is a species of rising prominence in the neurosciences due to its small size, ease of handling, fast breeding, and its shared functional and structural brain characteristics with Old World primates. With increasing attention on modeling human brain diseases in marmosets, understanding how to deliver therapeutic or neurotropic agents to the marmoset brain noninvasively is of great preclinical importance. In other species, including humans, transcranial focused ultrasound (tFUS) aided by intravenously injected microbubbles has proven to be a transient, reliable, and safe method for disrupting the blood-brain barrier (BBB), allowing the focal passage of therapeutic agents that do not otherwise readily traverse the tight endothelial junctions of the BBB. The critical gap that we address here is to document parameters to disrupt the BBB reliably and safely in marmosets using tFUS. By integrating our marmoset brain atlases and the use of a marmoset-specific stereotactic targeting system, we conduct a series of systematic transcranial sonication experiments in nine marmosets. We demonstrate the effects of center frequency, acoustic pressure, burst period, and duration, establish a minimum microbubble dose, estimate microbubble clearance time, and estimate the duration that the BBB remains open to passage. Successful BBB disruption is reported in vivo with MRI-based contrast agents, as well as Evans blue staining assessed ex vivo. Histology (Hematoxylin and Eosin staining) and immunohistochemistry indicate that the BBB can be safely and reliably opened with the parameters derived from these experiments. The series of experiments presented here establish methods for safely, reproducibly, and focally perturbing the BBB using tFUS in the common marmoset monkey that can serve as a basis for noninvasive delivery of therapeutic or neurotropic agents.

Clinical Sensitivity of the (1-3)-β-D-glucan Test for Predicting Candidemia

The sensitivity of the (1-3)-β-D-glucan (BDG) diagnostic test for candidemia varies in different clinical settings, and its usefulness in early diagnosis of candidemia is suboptimal. We evaluated the sensitivity of the test for early candidemia prediction. All adult patients with culture-proven candidemia who underwent a serum Goldstream Fungus (1-3)-β-D-Glucan Test within seven days prior to candidemia onset at a tertiary referral hospital between January 2017 and May 2021 were included. Any-positive BDG results within seven days prior to candidemia onset were obtained in 38 out of 93 (40.9%) patients. The positive rate increased when the test was performed near the day of candidemia onset (P=0.04) but reached only 52% on the day of candidemia onset. We observed no significant differences between BDG-positive and -negative groups in terms of underlying disease, risk factors for candidemia, clinical presentation, origin of candidemia, and 30-day mortality. Candida albicans was significantly associated with positive BDG results than with all-negative BDG results (P=0.04). The Goldstream BDG test is unreliable for candidemia prediction because of its low sensitivity. Negative BDG results in patients with a high risk of invasive candidiasis should be interpreted with caution.

Direct interhemispheric cortical communication via thalamic commissures: a new white-matter pathway in the primate brain

Cortical neurons of eutherian mammals project to the contralateral hemisphere, crossing the midline primarily via the corpus callosum and the anterior, posterior, and hippocampal commissures. We recently reported an additional commissural pathway in rodents, termed the thalamic commissures (TCs), as another interhemispheric axonal fiber pathway that connects cortex to the contralateral thalamus. Here, we demonstrate that TCs also exist in primates and characterize the connectivity of these pathways with high-resolution diffusion-weighted magnetic resonance imaging, viral axonal tracing, and functional MRI. We present evidence of TCs in both New World (Callithrix jacchus and Cebus apella) and Old World primates (Macaca mulatta). Further, like rodents, we show that the TCs in primates develop during the embryonic period, forming anatomical and functionally active connections of the cortex with the contralateral thalamus. We also searched for TCs in the human brain, showing their presence in humans with brain malformations, although we could not identify TCs in healthy subjects. These results pose the TCs as an important fiber pathway in the primate brain, allowing for more robust interhemispheric connectivity and synchrony and serving as an alternative commissural route in developmental brain malformations.

The relationship between organising pneumonia and invasive mould disease in patients with haematologic malignancy

BACKGROUND

Organising pneumonia (OP) is reported in patients with haematologic malignancy suspected of having invasive mould disease, yet little is known about this relationship.

OBJECTIVE

To investigate molecular evidence of invasive mould pneumonia in paraffin-embedded lung tissues from histologically diagnosed OP patients with suspected invasive mould pneumonia.

PATIENTS/METHODS

Patients with haematologic malignancy suspected to have invasive pulmonary mould disease who underwent lung biopsy at a tertiary hospital, Seoul, South Korea, between 2008 and 2020, were retrospectively reviewed. To find molecular evidence of fungal infection, PCR assay was used to detect Aspergillus- and Mucorales-specific DNA within OP lung tissue sections.

RESULTS

Forty-seven patients with suspected invasive mould pneumonia underwent lung biopsy and 15 (32%) were histologically diagnosed as OP without any evidence of fungal hyphae. Of these 15 patients, 3 (20%) received allogenic haematopoietic stem cell transplantation prior to developing OP. Before biopsy, 2 and 13 patients had probably and possible invasive mould disease, respectively. The median antifungal treatment length was 81 [8-114] days, and the median steroid treatment dosage was 0.35 mg/kg/day for 36 days (methylprednisolone equivalent doses), respectively. After biopsy, three patients with possible invasive mould infection revealed probable invasive pulmonary aspergillosis. From the 15 paraffin-embedded lung tissues, 6 (40%) exhibited positive PCR assay results for detecting Aspergillus- and Mucorales-specific DNA.

CONCLUSIONS

More than one third of OP cases in patients with suspected invasive mould pneumonia exhibited molecular evidence of invasive mould infection by fungus-specific PCR in lung tissues, likely associated with concurrent or prior fungal infection.

Epidemiology and characteristics of respiratory syncytial virus pneumonia in critically ill adults

Background

Severe RSV-associated pneumonia in adults has been rarely addressed. We investigated the burden and clinical characteristics of severe RSV-associated pneumonia in critically ill adult patients.

Methods

We analyzed a prospective cohort of 2,865 adults with severe pneumonia who were admitted to the intensive care unit in a 2,700-bed tertiary care hospital from 2010–2019. The epidemiology, characteristics, and outcomes of 92 cases of severe RSV-associated pneumonia and 163 cases of severe influenza virus (IFV)-associated pneumonia were compared.

Results

Of 1,589 cases of severe community-acquired pneumonia, the incidence of RSV-associated pneumonia was less than half that of IFV-associated pneumonia (3.4% vs. 8.1%). However, among 1,276 cases of severe hospital-acquired pneumonia (HAP), there were slightly more cases of RSV-associated than IFV-associated pneumonia (3.8% vs. 3.5%). During the nine epidemic seasons, RSV-A (five seasons) and RSV-B (four seasons) predominated alternately. Structural lung disease, diabetes mellitus, and malignancy were common underlying diseases in both groups. Immunocompromise (57.6% vs. 34.4%, p&lt;0.001) and hospital acquisition (47.8% vs. 23.9%, p&lt;0.001) were significantly more common in the RSV group. Co-infection with Streptococcus pneumoniae (3.3% vs. 9.8%, p=0.08) and methicillin-susceptible Staphylococcus aureus (1.1% vs. 6.8%, p=0.06) tended to be less frequent in the RSV group. The 90-day mortalities were high in both groups (39.1% vs. 40.5%, p=0.89).

Conclusion

RSV infection was associated with substantial morbidity and mortality in critically ill adult patients, similar to IFV. The relatively higher incidence of RSV in severe HAP suggests that the transmissibility of RSV can exceed that of IFV in a hospital setting.

Clinical characteristics and outcomes of invasive and non-invasive fusariosis in South Korea

BACKGROUND

Invasive fusariosis mainly affects immunocompromised patients including haematopoietic stem cell transplant recipients and those with haematologic malignancy. There are limited studies on invasive fusariosis in the Asia-Pacific region.

OBJECTIVE

To describe the clinical characteristics and outcomes of invasive and non-invasive fusariosis in South Korea.

PATIENTS/METHODS

From 2005 to 2020, patients with fusariosis who met the revised European Organisation for Research and Treatment of Cancer and the Mycoses Study Group criteria for the definition of proven or probable invasive fusariosis, and those with non-invasive fusariosis were retrospectively reviewed in a tertiary medical centre in Seoul, South Korea.

RESULTS

Overall, 26 and 75 patients had invasive and non-invasive fusariosis, respectively. Patients with invasive fusariosis commonly had haematologic malignancy (62%), were solid organ transplant recipients (23%), and had a history of immunosuppressant usage (81%). In non-invasive fusariosis, diabetes mellitus (27%) and solid cancer (20%) were common underlying conditions. Disseminated fusariosis (54%) and invasive pulmonary disease (23%) were the most common clinical manifestations of invasive fusariosis; skin infection (48%) and keratitis (27%) were the most common manifestations of non-invasive fusariosis. Twenty-eight-day and in-hospital mortalities were high in invasive fusariosis (40% and 52%, respectively). In multivariate analysis, invasive fusariosis (adjusted odds ratio, 9.6; 95% confidence interval 1.3-70.8; p = .03) was an independent risk factor for 28-day mortality.

CONCLUSIONS

Patients with invasive fusariosis were frequently immunocompromised, and more than half had disseminated fusariosis. Invasive fusariosis was associated with poor prognosis.

Efficacy of Doxycycline for Mild-to-Moderate Community-Acquired Pneumonia in Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Doxycycline has been recommended as a treatment option for non-severe community-acquired pneumonia (CAP) in adults. We sought to review the evidence for the efficacy of doxycycline in adult patients with mild-to-moderate CAP.

METHODS

We performed a systematic review and meta-analysis of randomized controlled trials (RCTs) of doxycycline versus comparator to assess the clinical efficacy. The primary outcome was the clinical cure rate. Random effects model meta-analyses were used to generate pooled odds ratio (OR) and evaluate heterogeneity (I2). Risk of bias (RoB) and quality of evidence (QoE) were evaluated using the Cochrane Risk of Bias 2.0 tool and GRADE methods, respectively.

RESULTS

We included 6 RCTs with 834 clinically evaluable patients. The trials were performed between 1984 and 2004. Comparators were 3 macrolides (roxithromycin, spiramycin, and erythromycin) and 3 fluoroquinolones (ofloxacin, fleroxacin, and levofloxacin). Four trials had an overall high RoB. The clinical cure rate was similar between the doxycycline and comparator groups (87.2% [381/437] vs 82.6% [328/397]; OR 1.29 [95% confidence interval {CI}: .73-2.28]; I2 = 30%; low QoE). Subgroup analysis of two studies with a low RoB showed significantly higher clinical cure rates in the doxycyline group (87.1% [196/225] vs 77.8% [165/212]; OR 1.92 [95% CI: 1.15-3.21]; P = .01; I2 = 0%). Adverse event rates were comparable between the doxycycline and comparator groups.

CONCLUSIONS

The efficacy of doxycycline was comparable to macrolides or fluoroquinolones in mild-to-moderate CAP and thus represents a viable treatment option. Considering the lack of recent trials, it warrants large-scale clinical trials.

Clinical significance and outcomes of Clostridium tertium bacteremia: analysis of 62 cases in neutropenic and non-neutropenic patients

The clinical significance of Clostridium tertium bacteremia is still uncertain. We evaluated the incidence, clinical characteristics, and outcomes of C. tertium bacteremia and identified differences between neutropenia and non-neutropenia. All adult patients with C. tertium bacteremia in a 2700-bed tertiary center between January 2004 and November 2021 were retrospectively enrolled. The first episode of C. tertium bacteremia in each patient was included in the analysis. Among 601 patients with Clostridium species bacteremia, 62 (10%) had C. tertium bacteremia, and of these 62 patients, 39 (63%) had had recent chemotherapy, and 31 (50%) had neutropenia or hematologic malignancy. C. tertium bacteremia originated frequently from a gastrointestinal tract infection such as enterocolitis (34%), primary bacteremia (29%), and secondary peritonitis (18%), and 34% of patients had polymicrobial bacteremia. Hematologic malignancy, prior antibiotic treatment, neutropenic enterocolitis, and primary bacteremia were significantly associated with C. tertium bacteremia in neutropenic patients, whereas solid tumor, hepatobiliary disease, secondary peritonitis, polymicrobial bacteremia, and a higher frequency of eradicable infection foci were significantly associated with C. tertium bacteremia in non-neutropenic patients. There was 15% 30-day mortality. APACHE II score (adjusted odds ratio [aOR], 1.5; 95% confidence interval [CI], 1.1-2.1) and secondary peritonitis (aOR, 25.9; 95% CI, 3.0-224.7) were independent risk factors for 30-day mortality. The prevalence of C. tertium bacteremia is low, and the characteristics of C. tertium bacteremia are significantly different between neutropenic and non-neutropenic patients. Appropriate investigation for gastrointestinal mucosal injury should be performed to improve treatment outcomes in this form of bacteremia.

Clinical and microbiological characteristics of rifampicin-resistant MRSA bacteraemia

OBJECTIVES

The clinical significance of rifampicin resistance in Staphylococcus aureus infections has not been demonstrated. Here, we evaluated the clinical characteristics of rifampicin-resistant S. aureus infection.

METHODS

Data were collected from adult patients who were hospitalized with MRSA bacteraemia between March 2007 and May 2020 at a tertiary hospital in South Korea. The clinical characteristics and treatment outcomes of patients infected with rifampicin-resistant MRSA were compared with those of rifampicin-susceptible isolates. All-cause death and recurrence of MRSA infection were assessed for 90 days.

RESULTS

Of the 961 patients with MRSA bacteraemia, 61 (6.3%) were infected by rifampicin-resistant isolates. The type of infection focus and duration of bacteraemia did not significantly differ between the two groups. Rifampicin-resistant MRSA isolates were more likely to have multidrug resistance and a higher vancomycin MIC relative to the rifampicin-susceptible isolates. The 90-day recurrence rate was higher in the patients infected with rifampicin-resistant MRSA compared with those with rifampicin-susceptible MRSA (18.0% versus 6.2%, P < 0.001), whereas the 90-day mortality was comparable between the two groups (27.9% versus 29.2%, P = 0.94). After adjusting for potential confounding factors, rifampicin resistance was significantly associated with 90-day recurrence (subdistributional HR: 2.31; 95% CI: 1.05-5.10; P = 0.04).

CONCLUSIONS

Rifampicin-resistant MRSA isolates showed distinct microbiological features in terms of multidrug resistance and a high vancomycin MIC. Although the management of MRSA bacteraemia was not significantly different between the two groups, recurrence was significantly more common in the rifampicin-resistant group. Rifampicin resistance may play a significant role in infection recurrence.

Bacterial Co-Infection and Empirical Antibacterial Therapy in Patients With COVID-19

BACKGROUND

The rate and composition of bacterial co-infection in patients with coronavirus disease 2019 (COVID-19) were evaluated when microbiological testing was conducted on the majority of patients. We also evaluated whether the use of empirical antibacterials was associated with mortality.

METHODS

In this retrospective study, all of the adult patients with COVID-19 hospitalized in a single tertiary hospital in South Korea between February 2020 and December 2021 were included. Bacterial co-infection was assessed by sputum cultures, blood cultures, and molecular testing, including polymerase chain reaction sputum testing and urinary antigen tests. Mortality was compared between patients who received empirical antibacterials and those who did not.

RESULTS

Of the 367 adult patients admitted during the study period, 300 (81.7%) had sputum culture results and were included in the analysis. Of these 300 patients, 127 (42.3%) had a history of antibiotic exposure. The co-infection rate within 48 hours was 8.3% (25/300): 6.4% (11/173) of patients without prior antibiotic exposure and 11% (14/127) of patients with prior antibacterial exposure. The co-infected bacteria were different according to antibacterial exposure before admission, and multi-drug resistant pathogens were detected exclusively in the antibacterial exposed group. Among the patients without positive results for the microbiological tests, empirical antibacterials were used in 33.3% of cases (100/300). Empirical antibacterial therapy was not significantly related to the 30-day mortality or in-hospital mortality rates in the study cohort before or after the propensity score-matching.

CONCLUSION

In this study including only patients underwent microbiological testing, bacterial co-infection was not frequent, and the co-infected organisms varied depending on previous antibacterial exposures. Given the rarity of co-infection and the lack of potential benefits, empiric antibacterial use in COVID-19 should be an important target of antibiotic stewardship.

A New Approach to Quantify and Grade Radiation Dermatitis Using Deep-Learning Segmentation in Skin Photographs

AIMS

Objective evaluation of radiation dermatitis is important for analysing the correlation between the severity of radiation dermatitis and dose distribution in clinical practice and for reliable reporting in clinical trials. We developed a novel radiation dermatitis segmentation system based on convolutional neural networks (CNNs) to consistently evaluate radiation dermatitis.

MATERIALS AND METHODS

The radiation dermatitis segmentation system is designed to segment the radiation dermatitis occurrence area using skin photographs and skin-dose distribution. A CNN architecture with a dilated convolution layer and skip connection was designed to estimate the radiation dermatitis area. Seventy-three skin photographs obtained from patients undergoing radiotherapy were collected for training and testing. The ground truth of radiation dermatitis segmentation is manually delineated from the skin photograph by an experienced radiation oncologist and medical physicist. We converted the skin photographs to RGB (red-green-blue) and CIELAB (lightness (L^∗), red-green (a^∗) and blue-yellow (b^∗)) colour information and trained the network to segment faint and severe radiation dermatitis using three different input combinations: RGB, RGB + CIELAB (RGBLAB) and RGB + CIELAB + skin-dose distribution (RGBLAB_D). The proposed system was evaluated using the Dice similarity coefficient (DSC), sensitivity, specificity and normalised Matthews correlation coefficient (nMCC). A paired t-test was used to compare the results of different segmentation performances.

RESULTS

Optimal data composition was observed in the network trained for radiation dermatitis segmentation using skin photographs and skin-dose distribution. The average DSC, sensitivity, specificity and nMCC values of RGBLAB_D were 0.62, 0.61, 0.91 and 0.77, respectively, in faint radiation dermatitis, and 0.69, 0.78, 0.96 and 0.83, respectively, in severe radiation dermatitis.

CONCLUSION

Our study showed that CNN-based radiation dermatitis segmentation in skin photographs of patients undergoing radiotherapy can describe radiation dermatitis severity and pattern. Our study could aid in objectifying the radiation dermatitis grading and analysing the reliable correlation between dosimetric factors and the morphology of radiation dermatitis.

305. Clinical scoring system to predict viable viral shedding in patients with COVID-19

Background

Centers for Disease Control and Prevention (CDC) recommends 5 to 20 days of isolation for COVID-19 patients depending on symptom duration and severity regardless of genomic PCR results or vaccination history. However, in real clinical practice, more individualized approach is required. We thus developed clinical scoring system to predict viable viral shedding in a given patient by using various factors affecting viable viral shedding.

Methods

We prospectively enrolled adult patients with SARS-CoV-2 infection admitted to tertiary hospital and day care center between February 2020 and January 2022. The daily dense respiratory sampling (i.e. saliva, sputum, or nasopharyngeal swabs) during the hospital and day care center stay were obtained. Genomic RNA viral load and viral culture were performed for these samples. Clinical predictors of negative viral culture results were identified using survival analysis and multivariable analysis.

Results

A total of 612 samples from 121 patients of varying degrees of severity were obtained. Of these, 494 (81%) samples were saliva, 63 (10%) were nasopharyngeal swab, and the remaining 55 (9%) were sputum. Of these 612 specimens, 154 (25%) samples revealed positive viral culture results. Univariate and multivariable Cox's time varying proportional hazard model revealed that symptom onset day, viral copy number, disease severity, organ transplant recipient, gender, and vaccination status were independently associated with viral culture results. We thus developed the 5-factor model from -3 to 3 points: viral copy number (-3 to 3 points depending on copy number), disease severity (1 point to moderate to critical diseases), organ transplant recipient (2 points), gender (-1 points to male), and vaccination status (-2 points to fully vaccinated status). The predictive culture-negative rates were calculated through the symptom onset day and the score of the day the sample was collected. Table 1.Prediction scores for negative viral culture resultsTable 2.Predicted Culture-negative Rates

Values in the table expressed as percentages.

Conclusion

Our clinical scoring system can provide objective probability of negative culture results in a given COVID-19 patient with genomic viral load, and appears to be useful to decide de-isolation policy depending on individualized factors associated with viable viral shedding beyond simple symptom-based isolation strategy by CDC.

Disclosures

All Authors: No reported disclosures.

1224. The incidence of severe C. striatum hospital-acquired pneumonia sharply increased and was associated with a high mortality rate

Background

The clinical information on patients with severe C. striatum pneumonia who require intensive care unit admission is currently limited.

Methods

We investigated the incidence and characteristics of severe Corynebacterium striatum pneumonia during a 6-year period at Asan Medical Center in comparison with severe pneumonia associated with MRSA.

Results

Between 2014 and 2019, there were 27 adult cases of severe C. striatum pneumonia. The majority of the cases (70.4%) were hospital-acquired pneumonia (HAP), and about half of the patients (51.9%) were immunocompromised. The incidence of C. striatum HAP significantly increased from 1.0% (2/200) in 2014-2015 to 5.4% (10/185) in 2018-2019 (P < 0.001), while the incidence of severe methicillin-resistant Staphylococcus aureus (MRSA) HAP significantly decreased from 12.0% to 2.7% during the same period. Of the 75 HAP cases whose bacterial pathogens were identified in 2018–2019, C. striatum was responsible for 13.3% of the cases. The 90-day mortality rates were similarly high in the C. striatum and MRSA groups (59.3% vs. 50.5%, P = 0.42).

Conclusion

In conclusion, C. striatum was a major pathogen of recent severe HAP and was associated with a substantially high mortality rate.

Disclosures

All Authors: No reported disclosures.

1082. Clinical Characteristics and Vertical Transmission of Pregnant Women with SARS-CoV-2 Infection and Their Neonates

Background

Pregnant women with SARS-CoV-2 infection are known to have a poor prognosis. In addition, the previous meta-analysis revealed that SARS-CoV-2 infection in neonates born from pregnant women with SARS-CoV-2 infection is about 2%. However, there are limited data on the clinical characteristics of pregnant women with SARS-CoV-2 infection and their neonates and the vertical transmission rate in South Korea.

Methods

Pregnant women confirmed as SARS-CoV-2 infection were retrospectively reviewed in Asan Medical Center from September 1 2020 to April 26 2022. All neonates from SARS-CoV-2-infected women underwent SARS-CoV-2 PCR within 24 hours after the birth and 48-hour interval if he or she stayed in the hospital.

Results

A total of 60 pregnant women gave birth by cesarean section (n=40, 67%) or vaginal delivery (n=20, 33%). Among them, three women gave birth to twins (63 neonates). Delivery was carried out at the average gestational age of 268 days (± 14.0), and 9 patients (15%) had underlying diseases. Of these 60 patients, 11 (18%) received COVID-19 vaccination. Pneumonia was confirmed by chest radiograph in 7 patients (12%), and 2 patient (3%) required supplemental oxygen therapy who eventually recovered. The mean weight of 63 newborns was 3137 g (± 558), and 8 neonate (13%) was a low-birth weight (< 2500 g), and 12 neonate (19%) was premature (< gestational age 37 weeks). Apgar score was 8.1 points (± 1.2) at 1 minute and 9.1 points (± 0.8) at 5 minutes. Five neonates (8%) required mechanical ventilation, who eventually recovered. All 63 neonates revealed negative SARS-CoV-2 PCR results with 24 hours after the birth. After 48 hours, 45 newborns exhibited negative SARS-CoV-2 PCR results. So, there was no vertical transmission among 63 neonates (0%, 95% CI 0-6).

Conclusion

Our experiences about pregnant women with SARS-CoV-2 infection revealed that obstetric outcomes were favorable and the vertical transmission risk was low. Balancing risks about the infection control of pregnant women and their neonates during the COVID-19 pandemic are needed.

Disclosures

All Authors: No reported disclosures.

2192. Clinical and Molecular Characteristics of Severe Respiratory Syncytial Virus Pneumonia in Critically Ill Adults

Background

Respiratory syncytial virus (RSV) has been increasingly recognized as a frustrating cause of morbidity and mortality in adults. However, the clinical impact and molecular characteristics of severe RSV-associated pneumonia in critically ill adult patients have rarely been addressed.

Methods

This study, nested in a prospective cohort of severe pneumonia, was conducted at a 2,700-bed tertiary care hospital and comprised two parts. In part 1, the clinical characteristics of severe RSV-associated pneumonia were compared with severe influenza virus (IFV)-associated pneumonia between 2010 and 2019. In part 2, we performed phylogenetic and amino acid analyses of the G protein of RSV strains from three groups of different infection severity between 2015 and 2019 (Figure 1). Figure 1.Clinical samples for whole-genome sequencing in part 2.

Results

In part 1, 92 RSV- and 163 IFV-positive patients were identified. Structural lung diseases, diabetes mellitus, and malignancy were common underlying diseases in both groups. Immunocompromise (57.6% vs. 34.4%, p &lt; 0.001) and hospital acquisition (47.8% vs. 23.9%, p &lt; 0.001) were significantly more common in the RSV group. Clinical manifestations at diagnosis between the groups were generally similar. The mortalities of patients in both groups were similarly high (Table 1). In part 2, 26 RSV strains from three groups (group 1: 11 strains, group 2: 8 strains, and group 3: 7 strains) were analyzed. All isolated RSV-A and -B strains belonged to the ON1 and the BA9 genotypes, respectively. The phylogenetic analysis revealed that the adult severe pneumonia strains clustered by contemporary strains rather than other severe pneumonia strains. There were no significantly different genetic variations among the three groups, including the subtype clades, amino acid sequence substitutions, and changes in potential glycosylation sites. Table 1.Characteristic and outcomes of 255 patients with virus-associated severe pneumonia

Conclusion

Severe RSV pneumonia was more commonly associated with hospital acquisition and immunocompromised status. Overall clinical features and mortalities of the RSV group were comparable to the IFV group. The molecular characteristics of RSV strains from the adults with severe pneumonia were not distinct from strains from non-pneumonic adults or children, underscoring that the severity of RSV respiratory tract infection is mainly determined by host factors, not by viral factors.

Disclosures

All Authors: No reported disclosures.

785. Bacterial Co-infection and Empirical Antibiotic Therapy in Patients with COVID-19

Background

Understanding the rate and composition of bacterial co-infection is important to determine antibiotic therapy in SARS-CoV-2 infection, but those vary according to healthcare settings and regional differences. We evaluated the rate of bacterial co-infection in hospitalized patients with COVID-19 in a single tertiary hospital in South Korea.

Methods

In this retrospective study, all the adult patients with COVID-19 hospitalized between Feb 2020 and Dec 2021 were included. Bacterial co-infection rate was assessed by results of sputum cultures, blood cultures, pneumococcal urinary antigen, Legionella urinary antigen, sputum Legionella pneumophilia PCR, and sputum multiplex PCR for Mycoplasma pneumoniae and Chlamydia pneumoniae. Characteristics and outcomes of patients were evaluated according to antibiotics exposure prior to hospitalization.

Results

Of 367 adult patients, 300 (81.7%) patients having sputum culture results were included in the analysis. Of these, 127 (42.3%) had a history of antibiotic exposure within 1 month before hospitalization. The coinfection rate within 48 hours of hospitalization was confirmed in 8.3% (25/300): 6.4% (11/163) of patients without prior antibiotic exposure and 11% (14/127) of patients with prior antibiotic exposure. In the group without prior antibiotic exposure, pathogens responsible for community-onset infections were isolated, whereas nosocomial pathogens were predominantly isolated in the antibiotic-exposed group. Empirical antibiotics were used in 144 (66%) of 275 patients without positive results for microbiological tests. Empirical antibiotic use in patients without positive results for microbiological tests was not significantly associated with 30-day mortality or in-hospital mortality after adjusting covariates including age, sex, comorbidity, anti-inflammatory treatment, and COVID-19 severity.

Conclusion

In this study with a high rate of microbiological testing, bacterial co-infection was not frequent, and the results varied depended on previous exposure to antibiotics. Given the rarity of bacterial co-infection and the lack of potential benefits of empirical antibiotic therapy, the antibiotic use in patients with COVID-19 should be restricted as an important target of antibiotic stewardship.

Disclosures

All Authors: No reported disclosures.