Antimicrobial therapy and outcome of methicillin-resistant Staphylococcus aureus endocarditis: A retrospective multicenter study in Japan

BACKGROUND

MRSA (methicillin-resistant Staphylococcus aureus)-infective endocarditis (IE) is associated with high morbidity and mortality. This study aimed to assess data from patients with MRSA-IE across multiple facilities in Japan, with a specific focus on antimicrobial therapy and prognosis.

METHODS

This retrospective study enrolled patients with a confirmed diagnosis of IE attributed to MRSA, spanning the period from January 2015 to April 2019.

RESULTS

Sixty-four patients from 19 centers were included, with a median age of 67 years. The overall mortality rate was 28.1% at 30 days, with an in-hospital mortality of 45.3%. The most frequently chosen initial anti-MRSA agents were glycopeptide in 67.2% of cases. Daptomycin and linezolid were selected as initial therapy in 23.4% and 17.2% of cases, respectively. Approximately 40% of all patients underwent medication changes due to difficulty in controlling infection or drug-related side effects. Significant prognostic factors by multivariable analysis were DIC for 30-day mortality and surgical treatment for 30-day and in-hospital mortality. For vancomycin as initial monotherapy, there was a trend toward a worse prognosis for 30-day and in-hospital mortality (OR, 6.29; 95%CI, 1.00-39.65; p = 0.050, OR, 3.61; 95%CI, 0.93-14.00; p = 0.064). Regarding the choice of initial antibiotic therapy, statistical analysis did not show significant differences in prognosis.

CONCLUSION

Glycopeptide and daptomycin were the preferred antibiotics for the initial therapy of MRSA-IE. Antimicrobial regimens were changed for various reasons. Prognosis was not significantly affected by choice of antibiotic therapy (glycopeptide, daptomycin, linezolid), but further studies are needed to determine which antimicrobials are optimal as first-line agents.

Mortality risk factors and fulminant sub-phenotype in anaerobic bacteremia: a 10-year retrospective, multicenter, observational cohort study

PURPOSE

During the last decade, the incidence of anaerobic bacteremia (AB) has been increasing. Patients with AB may develop complex underlying diseases, which can occasionally be accompanied by fatal or fulminant outcomes. However, the risk factors for AB-related mortality remain unclear. Herein, we sought to elucidate the risk factors for AB-related mortality.

METHODS

In this multicenter, retrospective, observational study, we enrolled patients with culture-proven AB from six tertiary hospitals in Japan, between January 2012 and December 2021. Data on patient and infection characteristics, laboratory findings, treatment, and outcome were collected, and their associations with mortality were analyzed.

RESULTS

A total of 520 participants were included. The 30-day mortality in the study cohort was 14.0% (73 patients), and malignant tumors were frequently observed comorbidities in 48% of the entire cohort. Multivariable logistic regression analysis showed a Charlson comorbidity score of > 6, serum creatinine level of > 1.17 mg/dL, and hypotension to be independent risk factors for 30-day mortality in AB (odds ratios [ORs] 2.12, 2.25, and 5.12, respectively; p < 0.05), whereas drainage significantly reduced this risk (OR, 0.28; p < 0.0001). Twelve patients (2.3% of the whole cohort and 16.4% of the deceased patients) presented with extremely rapid progression leading to fatal outcome, consistent with "fulminant AB."

CONCLUSIONS

This study identified acute circulatory dysfunction and performance of drainage as independent predictive factors for 30-day AB-related mortality and revealed the existence of a fulminant AB sub-phenotype. Our findings could serve as a practical guide to predict the clinical outcomes of AB.

The fatal case of "Pigmentibacter" bacteremia following aspiration pneumonia in elderly patient

"Pigmentibacter ruber" was first reported in 2021, a novel bacterium of the family Silvanigrellaceae, isolated from human blood of the patient with aspiration pneumonia after the drowning accident in Republic of China. However, until now, there is only one report describing "P. ruber" infection, and no case of isolation from natural environment has been reported so far. Thus, the infectivity and pathogenicity of "Pigmentibacter" spp. has not been clearly understood. In this report, we described the fatal case of "Pigmentibacter" bacteremia subsequently occurred after aspiration pneumonia probably due to accidental ingestion of irrigation water in the elderly patient. Despite administration of broad-spectrum antibiotic, the patient dramatically deteriorated and eventually deceased. Whole-genome sequencing showed the strain isolated from the patient was identified as "Pigmentibacter" sp. (designated as strain Takaoka) and antimicrobial sensitivity testing showed it displayed high minimum inhibitory concentrations against various antibiotics including β-lactam. Further studies are needed to clarify the clinical characteristics of "Pigmentibacter" and its relative's infections and their antimicrobial sensitivity; however, the present case supported the clinical characteristics of "Pigmentibacter" infection, which can lead to bacteremia following aspiration pneumonia caused by mis-swallowing contaminated water, and poor outcome potentially due to multidrug resistances.

High Incidence of Metastatic Infections in Panton-Valentine Leucocidin-Negative, Community-Acquired Methicillin-Resistant Staphylococcus aureus Bacteremia: An 11-Year Retrospective Study in Japan

Panton-Valentine leucocidin (PVL)-negative community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) was originally disseminated in Japan and has since replaced healthcare-associated MRSA (HA-MRSA). However, the clinical characteristics of CA-MRSA bacteremia (CA-MRSAB) compared with those of HA-MRSA bacteremia (HA-MRSAB) are unknown. We aim to clarify differences and investigate associations between the clinical manifestations and virulence genes associated with plasma-biofilm formation in PVL-negative CA-MRSA. From 2011 to 2021, when CA-MRSA dramatically replaced HA-MRSA, 79 MRSA strains were collected from blood cultures and analyzed via SCCmec typing and targeted virulence gene (lukSF-PV, cna, and fnbB) detection. The incidence of metastatic infection was significantly higher in CA-MRSAB than in HA-MRSAB. PVL genes were all negative, although cna and fnbB were positive in 55.6% (20/36) and 50% (18/36) of CA-MRSA strains and 3.7% (1/27) and 7.4% (2/27) of HA-MRSA strains, respectively. cna and fnbB carriage were not associated with the development of metastatic infections in MRSAB; however, the bacteremia duration was significantly longer in CA-MRSAB harboring cna. CA-MRSAB may be more likely to cause metastatic infections than HA-MRSAB. Since CA-MRSA is dominant in Japan, suspected metastatic infection foci should be identified by computed tomography, magnetic resonance imaging, and echocardiography when treating MRSAB.

Pulmonary abscess caused by Cladosporium cladosporioides after receiving outpatient chemotherapy

Cladosporium cladosporioides is one of the most ubiquitous dematiaceous fungi that seldomly occur human infection. Here, we demonstrate a rare case of pulmonary phaeohyphomycosis with a distinctive pulmonary lesion during the nadir period of outpatient chemotherapy against endometrial cancer. In addition to severe neutropenia, excessive exposure to C. cladosporioides at patient's residence was considered as dominant causative factor. More caution is considered necessary for pulmonary phaeohyphomycosis in patients who receive outpatient chemotherapy and are homebound during neutropenic status.

Predictive values of immune indicators on respiratory failure in the early phase of COVID-19 due to Delta and precedent variants

Background

Immune response indicators in the early phase of COVID-19, including interferon and neutralizing responses against SARS-CoV-2, which predict hypoxemia remains unclear.

Methods

This prospective observational study recruited patients hospitalized with COVID-19 (before emergence of omicron variant). As the immune indicators, we assessed the serum levels of IFN-I/III, IL-6, CXCL10 and VEGF, using an ELISA at within 5 days after the onset of symptoms, and serum neutralizing responses using a pseudovirus assay. We also assessed SARS-CoV-2 viral load by qPCR using nasal-swab specimens and serum, to assess the association of indicators and viral distribution.

Results

The study enrolled 117 patients with COVID-19, of which 28 patients developed hypoxemia. None received vaccine before admission. Serum IFN-I levels (IFN-α and IFN-β), IL-6, CXCL10, LDH and CRP were significantly higher in patients who developed hypoxemia. A significant association with nasopharyngeal viral load was observed only for IFN-I. The serum levels of IFN-α, IL-6, CXCL10 were significantly associated with the presence of RNAemia. Multivariable analysis showed higher odds ratio of IFN-α, with cut-off value of 107 pg/ml, in regard to hypoxemia (Odds ratio [OR]=17.5; 95% confidence interval [CI], 4.7-85; p<0.001), compared to those of IL-6, >17.9 pg/ml (OR=10.5; 95% CI, 2.9-46; p<0.001).

Conclusions

This study demonstrated that serum IFN-α levels in the early phase of SARS-CoV-2 infection strongly predict hypoxemic respiratory failure in a manner different from that of the other indicators including IL-6 or humoral immune response, and instead sensitively reflect innate immune response against SARS-CoV-2 invasion.

A Multicenter Randomized Controlled Trial To Evaluate the Efficacy and Safety of Nelfinavir in Patients with Mild COVID-19

Nelfinavir, an orally administered inhibitor of human immunodeficiency virus protease, inhibits the replication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in vitro. We conducted a randomized controlled trial to evaluate the clinical efficacy and safety of nelfinavir in patients with SARS-CoV-2 infection. We included unvaccinated asymptomatic or mildly symptomatic adult patients who tested positive for SARS-CoV-2 infection within 3 days before enrollment. The patients were randomly assigned (1:1) to receive oral nelfinavir (750 mg; thrice daily for 14 days) combined with standard-of-care or standard-of-care alone. The primary endpoint was the time to viral clearance, confirmed using quantitative reverse-transcription PCR by assessors blinded to the assigned treatment. A total of 123 patients (63 in the nelfinavir group and 60 in the control group) were included. The median time to viral clearance was 8.0 (95% confidence interval [CI], 7.0 to 12.0) days in the nelfinavir group and 8.0 (95% CI, 7.0 to 10.0) days in the control group, with no significant difference between the treatment groups (hazard ratio, 0.815; 95% CI, 0.563 to 1.182; P = 0.1870). Adverse events were reported in 47 (74.6%) and 20 (33.3%) patients in the nelfinavir and control groups, respectively. The most common adverse event in the nelfinavir group was diarrhea (49.2%). Nelfinavir did not reduce the time to viral clearance in this setting. Our findings indicate that nelfinavir should not be recommended in asymptomatic or mildly symptomatic patients infected with SARS-CoV-2. The study is registered with the Japan Registry of Clinical Trials (jRCT2071200023). IMPORTANCE The anti-HIV drug nelfinavir suppresses the replication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in vitro. However, its efficacy in patients with COVID-19 has not been studied. We conducted a multicenter, randomized controlled trial to evaluate the efficacy and safety of orally administered nelfinavir in patients with asymptomatic or mildly symptomatic COVID-19. Compared to standard-of-care alone, nelfinavir (750 mg, thrice daily) did not reduce the time to viral clearance, viral load, or the time to resolution of symptoms. More patients had adverse events in the nelfinavir group than in the control group (74.6% [47/63 patients] versus 33.3% [20/60 patients]). Our clinical study provides evidence that nelfinavir, despite its antiviral effects on SARS-CoV-2 in vitro, should not be recommended for the treatment of patients with COVID-19 having no or mild symptoms.

Dominant CT Patterns and Immune Responses during the Early Infection Phases of Different SARS-CoV-2 Variants

Ground-glass opacity (GGO) and organizing pneumonia (OP) are dominant pulmonary CT lesions associated with COVID-19. However, the role of different immune responses in these CT patterns remains unclear, particularly following the emergence of the Omicron variant. In this prospective observational study, we recruited patients hospitalized with COVID-19, before and after the emergence of Omicron variants. Semi-quantitative CT scores and dominant CT patterns were retrospectively determined for all patients within five days of symptom onset. Serum levels of IFN-α, IL-6, CXCL10, and VEGF were assessed using ELISA. Serum-neutralizing activity was measured using a pseudovirus assay. We enrolled 48 patients with Omicron variants and 137 with precedent variants. While the frequency of GGO patterns was similar between the two groups, the OP pattern was significantly more frequent in patients with precedent variants. In patients with precedent variants, IFN-α and CXCL10 levels were strongly correlated with GGO, whereas neutralizing activity and VEGF were correlated with OP. The correlation between IFN-α levels and CT scores was lower in patients with Omicron than in those with precedent variants. Compared to preceding variants, infection with the Omicron variant is characterized by a less frequent OP pattern and a weaker correlation between serum IFN-α and CT scores.

Effectiveness and Safety of Linezolid Versus Vancomycin, Teicoplanin, or Daptomycin against Methicillin-Resistant Staphylococcus aureus Bacteremia: A Systematic Review and Meta-Analysis

Vancomycin (VCM) and daptomycin (DAP) are standard therapies for methicillin-resistant Staphylococcus aureus (MRSA) bacteremia, despite concerns regarding clinical utility and growing resistance. Linezolid (LZD) affords superior tissue penetration to VCM or DAP and has been successfully used as salvage therapy for persistent MRSA bacteremia, indicating its utility as a first-choice drug against MRSA bacteremia. In a systematic review and meta-analysis, we compared the effectiveness and safety of LZD with VCM, teicoplanin (TEIC), or DAP in patients with MRSA bacteremia. We evaluated all-cause mortality as the primary effectiveness outcome, clinical and microbiological cure, hospital length of stay, recurrence, and 90-day readmission rates as secondary effectiveness outcomes, and drug-related adverse effects as primary safety outcomes. We identified 5328 patients across 2 randomized controlled trials (RCTs), 1 pooled analysis of 5 RCTs, 1 subgroup analysis (1 RCT), and 5 case-control and cohort studies (CSs). Primary and secondary effectiveness outcomes were comparable between patients treated with LZD versus VCM, TEIC, or DAP in RCT-based studies and CSs. There was no difference in adverse event incidence between LZD and comparators. These findings suggest that LZD could be a potential first-line drug against MRSA bacteremia as well as VCM or DAP.

Neutralizing Antibody Response of the Wild-Type/Omicron BA.1 Bivalent Vaccine as the Second Booster Dose against Omicron BA.2 and BA.5

In addition to the original monovalent vaccines available for SARS-CoV-2, bivalent vaccines covering wild-type (WT) and Omicron BA.1 are also available. However, there is a lack of real-world data on the immunogenicity of bivalent vaccines as second boosters against the dominant Omicron sublineages, including BA.2 and BA.5. Healthcare workers (n = 565) who received the first booster vaccination were followed for 2 weeks after the second booster dose of the monovalent mRNA-1273 (WT group, n = 168) and bivalent BNT162b2 (WT+BA.1 group, n = 23) vaccines. Participants with previous SARS-CoV-2 infections were excluded from the study. The anti-receptor binding domain (RBD) antibody levels after the second booster dose in the WT and WT+BA.1 group were similar (median [interquartile range], 26,262.0 [16,951.0 to 38,137.0] U/mL versus 24,840.0 [14,828.0 to 41,460.0] U/mL, respectively). Although the neutralization activities of the pooled sera were lower against BA.5 than against other variants in both groups, the activities against BA.2 and BA.5 in the WT+BA.1 group were higher than those of the WT group in both pseudotyped and live virus assays. Vaccine-related symptoms, including systemic and local symptoms, were strongly correlated with anti-RBD antibody levels and neutralizing titers. In conclusion, the second booster dose of the bivalent (WT/Omicron BA.1) vaccine induced higher neutralizing activity against BA.2 and BA.5 than that of the original monovalent vaccine. IMPORTANCE Although Omicron BA.1-containing bivalent vaccines have been authorized, real-world data validating their safety and antibody responses remain scarce. We conducted a prospective longitudinal study to assess the safety, immunogenicity, and reactogenicity of the second booster dose with the Omicron BA.1 bivalent vaccine in health care workers. Compared with the original monovalent vaccine, the bivalent (WT+BA.1) vaccine elicited higher levels of neutralizing antibodies against the Omicron BA.2 and BA.5 subvariants. The frequency of adverse events after the second booster dose was similar to that of the monovalent vaccine. BA.5-neutralizing antibodies induced by the bivalent Omicron BA.1-containing vaccine were expected to decline. A prospective longitudinal study should be performed to determine the persistence of the humoral immunity.

Comparative Study of Three Commercial Blood (1→3)-β-D-glucan Detection Reagents for Invasive Mycosis

BACKGROUND

β-D-glucan detection is a useful diagnostic indicator of invasive mycosis. However, the differences among the commercial β-D-glucan assays are unclear. Herein, we explored the diagnostic value of various β-D-glucan assay reagents.

METHODS

This prospective observational study involved 175 eligible patients suspected to have fungal infections. For all participants, culture examinations were conducted with specimens obtained from the infected site (or blood culture), and β-D-glucan was measured using three commercial kits: Wako β-glucan test (Wako), Fungitech G-test MKII "Nissui" (MKII), and Fungitech G-test ES "Nissui" (ES).

RESULTS

A total of 163 participants were included. Among them, 32 cases of invasive mycosis, 34 cases with mycotic colonization infection, and 97 cases with non-fungal infections were confirmed. Regarding the diagnostic value of the commercial kits for invasive mycosis, the areas under the receiver operating characteristic curves were > 0.8 for all the agents. However, on the basis of the cut-off value set by the manufacturer, the sensitivity and specificity of the three kits for definitive invasive infection were 80.0% and 90.6% with Wako, 80.0% and 80.7% with MKII, and 86.7% and 71.8% with ES, respectively. Moreover, the rate of false-positive β-D-glucan elevation detection in patients with negative fungal culture was 9.3% with Wako, 18.6% with MKII, and 23.7% with ES.

CONCLUSION

Despite the high diagnostic value of β-D-glucan detection in invasive fungal infections, caution should be exercised in interpreting the value of the assay reagents.

Population Pharmacokinetic Model for Unbound Concentrations of Daptomycin in Patients with MRSA Including Patients Undergoing Hemodialysis

BACKGROUND AND OBJECTIVE

Unbound daptomycin concentrations are responsible for pharmacologically beneficial and adverse effects, although most previous reports have been limited to the use of total concentrations. We developed a population pharmacokinetic model to predict both total and unbound daptomycin concentrations.

METHODS

Clinical data were collected from 58 patients with methicillin-resistant Staphylococcus aureus including patients undergoing hemodialysis. A total of 339 serum total and 329 unbound daptomycin concentrations were used for model construction.

RESULTS

Total and unbound daptomycin concentration was explained by a model that assumed first-order distribution with two compartments, and first-order elimination. Normal fat body mass was identified as covariates. Renal function was incorporated as a linear function of renal clearance and independent non-renal clearance. The unbound fraction was estimated to be 0.066 with a standard albumin of 45 g/L and standard creatinine clearance of 100 mL/min. Simulated unbound daptomycin concentration was compared with minimum inhibitory concentration as a measure of clinical effectiveness and exposure-level-related induction of creatine phosphokinase elevation. The recommended doses were 4 mg/kg for patients with severe renal function [creatinine clearance (CLcr) ≤ 30 mL/min] and 6 mg/kg for patients with mild to moderate renal function (CLcr > 30 and ≤ 60 mL/min). A simulation indicated that dose adjusted by body weight and renal function improved target attainment.

CONCLUSIONS

This population pharmacokinetics model for unbound daptomycin could help clinicians to select the appropriate dose regimen for patients undergoing daptomycin treatment and reduce associated adverse effects.

Multicenter, single-blind, randomized controlled study of the efficacy and safety of favipiravir and nafamostat mesilate in patients with COVID-19 pneumonia

OBJECTIVES

To evaluate the efficacy and safety of nafamostat combined with favipiravir for the treatment of COVID-19.

METHODS

We conducted a multicenter, randomized, single-blind, placebo-controlled, parallel assignment study in hospitalized patients with mild-to-moderate COVID-19 pneumonia. Patients were randomly assigned to receive favipiravir alone (n = 24) or nafamostat with favipiravir (n = 21). The outcomes included changes in the World Health Organization clinical progression scale score, time to improvement in body temperature, and improvement in oxygen saturation (SpO₂).

RESULTS

There was no significant difference in the changes in the clinical progression scale between nafamostat with favipiravir and favipiravir alone groups (median, -0.444 vs -0.150, respectively; least-squares mean difference, -0.294; P = 0.364). The time to improvement in body temperature was significantly shorter in the combination group (5.0 days; 95% confidence interval, 4.0-7.0) than in the favipiravir group (9.0 days; 95% confidence interval, 7.0-18.0; P =0.009). The changes in SpO₂ were greater in the combination group than in the favipiravir group (0.526% vs -1.304%, respectively; least-squares mean difference, 1.831; P = 0.022). No serious adverse events or deaths were reported, but phlebitis occurred in 57.1% of the patients in the combination group.

CONCLUSION

Although our study showed no differences in clinical progression, earlier defervescence, and recovery of SpO₂ were observed in the combination group.

Analytical sensitivity of six lateral flow antigen test kits for variant strains of SARS-CoV-2

INTRODUCTION

The lateral flow antigen test is a useful tool for rapid diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. The analytical sensitivity of six lateral flow antigen test kits was compared.

METHODS

The limit of detection (LoD) and time to positive results were evaluated for six lateral flow tests including ImmunoArrow®, ESPLINE® SARS-CoV-2, QuickNavi™ COVID19 Ag, ImmunoAce® SARS-CoV-2, Panbio™ COVID-19 Ag Rapid Test Device, and SARS-CoV-2 Rapid Antigen Test using the heat-inactivated virus. The LoD of ImmunoArrow® against the Omicron variants was compared with that against the wild-type using recombinant proteins.

RESULTS

ImmunoArrow® and ESPLINE® showed the lowest LoD. The time to positive results of all tests except for ESPLINE® was within 200 s in the evaluation at high dose of antigens (2.5 × 10⁵ TCID₅₀/mL) and 500 s in the evaluation at low dose of antigens (2.5 × 10⁴ TCID₅₀/mL). The LoD of ImmunoArrow® against the Omicron variants was the same concentration against the wild-type antigen.

CONCLUSIONS

ImmunoArrow® detected SARS-CoV-2 antigens including the Omicron variants with good sensitivity among the six lateral flow antigen tests. These finding support that it can support the rapid diagnosis of COVID-19 with the good sensitivity.

Clinical Features of Hypoxemia Due to Infection Under Home-Based Medication During the COVID-19 Pandemic Period

BACKGROUND

Despite the growing demand for home-based medication during the COVID-19 pandemic period, there remains scarce evidence of hypoxemic infection in home-care settings. In this study, we investigated the clinical features of hypoxemic respiratory failure due to infection during the period under home-based medication (defined as 'home-care-acquired infection').

METHODS

This retrospective observational study enrolled patients with home-care-acquired infection, other than COVID-19, in two home-care clinics in Sapporo, Japan, between April 2020 and May 2021 (the early phase of the COVID-19 pandemic). The participants were divided into two groups according to whether they required additional home oxygen therapy, and were compared to assess the predictors of hypoxemic respiratory failure. Furthermore, the clinical features were compared with those in patients aged >60 years with COVID-19 who were admitted to Toyama University Hospital during the same period.

RESULTS

A total of 107 patients with home-care-acquired infections were included in the study (median age, 82 years). Twenty-two patients required home oxygen therapy, and 85 did not. Thirty-day mortality rates were 32% and 8%. Among the patients in the hypoxemia group, none had desired a care-setting transition, following the advanced care planning. Multivariable logistic regression analysis showed that initial antibiotic treatment failure and malignant disease were independently associated with hypoxemic respiratory failure (odds ratio, 7.28 and 7.10; p=0.023 and p<0.005, respectively). In comparison with hypoxemia in the COVID-19 cohort, the lower incidence of febrile co-habitants and earlier onset of hypoxemia were significant in those due to home-care-acquired infection.

CONCLUSION

This study demonstrated that hypoxemia due to home-care-acquired infection was characterized by distinct features, possibly different from those due to COVID-19 in the early pandemic period.

Effect of Casirivimab/Imdevimab Treatment on Serum Type I Interferon Levels in SARS-CoV-2 Infection

The effects of casirivimab and imdevimab (C/I) on the innate immune response against SARS-CoV-2 infection remain unclear. We evaluated the effect of C/I on type I interferon (IFN-I) and cytokines in patients with SARS-CoV-2 infection. This prospective observational study recruited consecutive patients hospitalized with SARS-CoV-2 infection. Blood levels of IFN-I and cytokines before and after C/I administration were assessed using enzyme-linked immunoassay. The study enrolled 29 patients in the C/I group. In addition, 11 patients who received remdesivir and dexamethasone (R/D group) during the early phase (≤5 days after the onset of symptoms) were included as a comparator group. After treatment, IFN-α and IFN-β levels decreased significantly in both the C/I group and R/D group, whilst the post-treatment neutrophil-to-lymphoid ratio increased in the early C/I group but not the R/D group. In the C/I group, temporal temperature elevation and hypoxemia were observed after treatment in 58.6% and 41.4% of the cohort, respectively. However, most patients recovered by 5 days after treatment. This study could demonstrate the high therapeutic effect of C/I with an antibody-dependent enhancement-like response and decreased IFN-I production, which was likely due to the immediate induction of an antibody-dependent immune response against SARS-CoV-2.

Effectiveness of the third dose of BNT162b2 vaccine on neutralizing Omicron variant in the Japanese population

Introduction

The vaccine against SARS-CoV-2 provides humoral immunity to fight COVID-19; however, the acquired immunity gradually declines. Booster vaccination restores reduced humoral immunity; however, its effect on newly emerging variants, such as the Omicron variant, is a concern. As the waves of COVID-19 cases and vaccine programs differ between countries, it is necessary to know the domestic effect of the booster.

Methods

Serum samples were obtained from healthcare workers (20–69 years old) in the Pfizer BNT162b2 vaccine program at the Toyama University Hospital 6 months after the second dose (6mA2D, n = 648) and 2 weeks after the third dose (2wA3D, n = 565). The anti-SARS-CoV-2 antibody level was measured, and neutralization against the wild-type and variants (Delta and Omicron) was evaluated using pseudotyped viruses. Data on booster-related events were collected using questionnaires.

Results

The median anti-SARS-CoV-2 antibody was >30.9-fold elevated after the booster (6mA2D, 710.0 U/mL [interquartile range (IQR): 443.0–1068.0 U/mL]; 2wA3D, 21927 U/mL [IQR: 15321.0–>25000.0 U/mL]). Median neutralizing activity using 100-fold sera against wild-type-, Delta-, and Omicron-derived variants was elevated from 84.6%, 36.2%, and 31.2% at 6mA2D to >99.9%, 99.1%, and 94.6% at 2wA3D, respectively. The anti-SARS-CoV-2 antibody levels were significantly elevated in individuals with fever ≥37.5 °C, general fatigue, and myalgia, local swelling, and local hardness.

Conclusion

The booster effect, especially against the Omicron variant, was observed in the Japanese population. These findings contribute to the precise understanding of the efficacy and side effects of the booster and the promotion of vaccine campaigns.

Circulating Type I Interferon Levels in the Early Phase of COVID-19 Are Associated With the Development of Respiratory Failure

Background

The role of type I interferons (IFNs) in the early phase of COVID-19 remains unclear.

Objectives

To evaluate the relationship between IFN-I levels in patients with COVID-19 and clinical presentation, SARS-CoV-2 viral load, and other major pro-inflammatory cytokines.

Methods

This prospective observational study recruited patients hospitalized with COVID-19. The levels of interferon-alpha (IFN-α), interferon-beta (IFN-β), interleukin-6 (IL-6), and C-X-C motif chemokine ligand (CXCL10) within 5 days after symptom onset were measured using an ELISA, in serum from blood collected within 5 days after the onset of symptoms. The SARS-CoV-2 viral load was determined via qPCR using nasal-swab specimens and serum.

Results

The study enrolled 50 patients with COVID-19. IFN-α levels were significantly higher in patients who presented with pneumonia or developed hypoxemic respiratory failure (p &lt; 0.001). Furthermore, IFN-α levels were associated with viral load in nasal-swab specimens and RNAemia (p &lt; 0.05). In contrast, there was no significant association between IFN-β levels and the presence of pneumonia or RNAemia, despite showing a stronger association with nasal-swab viral load (p &lt; 0.001). Correlation analysis showed that the serum levels of IFN-α significantly correlated with those of IFN-β, IL-6, and CXCL10, while the levels of IFN-β did not correlate with those of IL-6 or CXCL10.

Conclusions

Serum IFN-I levels in the early phase of SARS-CoV-2 infection were higher in patients who developed hypoxemic respiratory failure. The association between IFN-α, IL-6, and CXCL10 may reflect the systemic immune response against SARS-CoV-2 invasion into pulmonary circulation, which might be an early predictor of respiratory failure due to COVID-19.

Novel super-neutralizing antibody UT28K is capable of protecting against infection from a wide variety of SARS-CoV-2 variants

Many potent neutralizing SARS-CoV-2 antibodies have been developed and used for therapies. However, the effectiveness of many antibodies has been reduced against recently emerging SARS-CoV-2 variants, especially the Omicron variant. We identified a highly potent SARS-CoV-2 neutralizing antibody, UT28K, in COVID-19 convalescent individuals who recovered from a severe condition. UT28K showed efficacy in neutralizing SARS-CoV-2 in an in vitro assay and in vivo prophylactic treatment, and the reactivity to the Omicron strain was reduced. The structural analyses revealed that antibody UT28K Fab and SARS-CoV-2 RBD protein interactions were mainly chain-dominated antigen-antibody interactions. In addition, a mutation analysis suggested that the emergence of a UT28K neutralization-resistant SARS-CoV-2 variant was unlikely, as this variant would likely lose its competitive advantage over circulating SARS-CoV-2. Our data suggest that UT28K offers potent protection against SARS-CoV-2, including newly emerging variants.

Age-Dependent Reduction in Neutralization against Alpha and Beta Variants of BNT162b2 SARS-CoV-2 Vaccine-Induced Immunity

Vaccines against severe acute respiratory syndrome coronavirus-2 have been introduced. To investigate the relationship between vaccine-induced humoral immunity and patient age, we measured antibody levels and neutralization in vaccinated sera. Sera from 13 to 17 days after the second dose of the BNT162b2 vaccine were collected from health care workers at the University of Toyama (n = 740). Antibody levels were measured by the anti-receptor binding domain antibody test (anti-RBD test), and neutralization against wild-type (WT), α- and β-variant pseudotyped viruses were assayed using a high-throughput chemiluminescent reduction neutralizing test (htCRNT; positivity cutoff, 50% neutralization at serum dilution 1:100). Basic clinical characteristics were obtained from questionnaires. Antibodies were confirmed in all participants in both the anti-RBD test (median, 2,112 U/ml; interquartile range [IQR], 1,275 to 3,390 U/ml) and the htCRNT against WT (median % inhibition, >99.9; IQR, >99.9 to >99.9). For randomly selected sera (n = 61), 100.0% had positive htCRNT values against the α- and β-derived variants. Among those who answered the questionnaire (n = 237), the values of the anti-RBD test were negatively correlated with age in females (P < 0.01). An age-dependent decline in neutralization was observed against the variants but not against the wild-type virus (wild type, P = 0.09; α, P < 0.01; β, P < 0.01). The neutralizing activity induced by BNT162b2 was obtained not only against the wild-type virus, but also against the variants; however, there was an age-dependent decrease in the latter. Age-related heterogeneity of vaccine-acquired immunity is a concern in preventive strategies in the era dominated by variants. IMPORTANCE Since mRNA vaccines utilize wild-type SARS-CoV-2 spike protein as an antigen, there are potential concerns about acquiring immunity to variants of this virus. The neutralizing activity in BNT162b2-vaccinated individuals was higher against the wild-type virus than against its variants; this effect was more apparent in older age groups. This finding suggests that one of the weaknesses of the mRNA vaccine is the high risk of variant infection in the elderly population. Because the elderly are at a higher risk of SARS-CoV-2 infection, the age-dependent decline of neutralization against viral variants should be considered while planning vaccination programs that include boosters.

Development of a simple method for measuring tedizolid concentration in human serum using HPLC with a fluorescent detector

The objective of the present study was to develop a method to measure tedizolid (TZD) concentration for studying target concentration intervention, pharmacokinetics, and pharmacodynamics of TZD. We established a high-performance liquid chromatography-fluorescence detector assay to measure the TZD concentration in serum for clinical application. Chromatographic separation was carried out on a 5 μm octadecyl silane hypersil column 150 mm × 4.6 mm. The mobile phase consisted of 0.1 M phosphoric acid and methanol (60:40, pH 7.0). Detection was performed at 300 nm and 340 nm for the excitation and emission wavelengths, respectively. The average retention times of TZD and the internal standard were 12.9 and 8.8 min, respectively. High linearity was exhibited over a concentration range of 0.025 to 10.0 μg/mL for TZD (R2 > 0.999). The intra- and inter-assay accuracies of TZD were 99.2% to 107.0% and 99.2% to 107.7%, respectively. The lower limit of quantitation and the lower limit of detection for TZD measurement were 0.025 and 0.01 μg/mL, respectively. The extraction recoveries of TZD were 100.4% to 114.1%.The high-performance liquid chromatography method developed in this study could separate the analytes with a single eluent (isocratic system), within a total run time of 15 min. Both TZD and IS were well separated, without interference from the peaks. Sharp peaks were observed in the chromatograms; problems such as double peaks, shoulder peaks, and broadened peaks were not observed. The proposed method showed acceptable analytical performance and could be used to evaluate serum TZD concentrations in patients.

SARS-CoV-2 RNAemia with a higher nasopharyngeal viral load is strongly associated with disease severity and mortality in patients with COVID-19

This study aimed to determine the frequency of SARS‐CoV‐2 RNA in serum and its association with the clinical severity of COVID‐19. This retrospective cohort study performed at Toyama University Hospital included consecutive patients with confirmed COVID‐19. The prevalence of SARS‐CoV‐2 RNAemia and the strength of its association with clinical severity variables were examined. Fifty‐six patients were included in this study. RNAemia was detected in 19.6% (11/56) patients on admission, and subsequently in 1.0% (1/25), 50.0% (6/12), and 100.0% (4/4) moderate, severe, and critically ill patients, respectively. Patients with RNAemia required more frequent oxygen supplementation (90.0% vs. 13.3%), ICU admission (81.8% vs. 6.7%), and invasive mechanical ventilation (27.3% vs. 0.0%). Among patients with RNAemia, the median viral loads of nasopharyngeal (NP) swabs that were collected around the same time as the serum sample were significantly higher in critically ill (5.4 log₁₀ copies/μl; interquartile range [IQR]: 4.2–6.3) than in moderate‐severe cases (2.6 log₁₀ copies/μl; [IQR: 1.1–4.5]; p = 0.030) and were significantly higher in nonsurvivors (6.2 log₁₀ copies/μl [IQR: 6.0–6.5]) than in survivors (3.9 log₁₀ copies/μl [IQR: 1.6–4.6]; p = 0.045). This study demonstrated a relatively high proportion of SARS‐CoV‐2 RNAemia and an association between RNAemia and clinical severity. Moreover, among the patients with RNAemia, the viral loads of NP swabs were correlated with disease severity and mortality, suggesting the potential utility of combining serum testing with NP tests as a prognostic indicator for COVID‐19, with higher quality than each separate test.

Delayed neutralizing antibody response in the acute phase correlates with severe progression of COVID-19

Adaptive immunity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) dynamics remain largely unknown. The neutralizing antibody (NAb) levels in patients with coronavirus disease 2019 (COVID-19) are helpful for understanding the pathology. Using SARS-CoV-2 pseudotyped virus, serum sample neutralization values in symptomatic COVID-19 patients were measured using the chemiluminescence reduction neutralization test (CRNT). At least two sequential serum samples collected during hospitalization were analyzed to assess NAbs neutralizing activity dynamics at different time points. Of the 11 patients, four (36.4%), six (54.5%), and one (9.1%) had moderate, severe, and critical disease, respectively. Fifty percent neutralization (N50%-CRNT) was observed upon admission in 90.9% (10/11); all patients acquired neutralizing activity 2-12 days after onset. In patients with moderate disease, neutralization was observed at earliest within two days after symptom onset. In patients with severe-to-critical disease, neutralization activity increased, plateauing 9-16 days after onset. Neutralization activity on admission was significantly higher in patients with moderate disease than in patients with severe-to-critical disease (relative % of infectivity, 6.4% vs. 41.1%; P = .011). Neutralization activity on admission inversely correlated with disease severity. The rapid NAb response may play a crucial role in preventing the progression of COVID-19.

Prolonged viral clearance of severe acute respiratory syndrome coronavirus 2 in the older aged population

INTRODUCTION

The detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA by quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) is the standard method for the diagnosis of coronavirus disease 2019 (COVID-19). This PCR test can be positive even in patients who have recovered from the disease, and the duration for achieving viral clearance has not been clarified yet.

METHODS

This study was conducted between April 3, 2020, and June 17, 2020, at the Toyama University Hospital and the Toyama Rehabilitation Home. We collected the data of patients with COVID-19, analyzing the duration until twice-consecutive negative qRT-PCR test.

RESULTS

A total of 42 patients were enrolled. The median duration of the twice-consecutive negative qRT-PCR test was 29.0 d (interquartile range: 25.75-35.25). The longest duration of viral shedding was 73 d. The duration of viral clearance was significantly longer in the older (>65 years) group than in the younger group (34.5 d vs. 25.0 d, P < 0.0001).

CONCLUSION

This study demonstrated that viral clearance tends to be sustained in the older adults.

Initially Reduced Linezolid Dosing Regimen to Prevent Thrombocytopenia in Hemodialysis Patients

This retrospective cohort study investigated the effects of an initially reduced linezolid dosing regimen in hemodialysis patients through therapeutic drug monitoring (TDM). Patients were divided into two groups depending on their initial dose of linezolid (standard dose of 600 mg every 12 h or initially reduced dose of 300 mg every 12 h/600 mg every 24 h). The cumulative incidence rates of thrombocytopenia and severe thrombocytopenia were compared between both groups using the Kaplan-Meier method and log-rank test. Eleven episodes of 8 chronic hemodialysis patients were included; 5 were in the initially reduced-dose group. Thrombocytopenia developed in 81.8% of patients. The cumulative incidence rates of thrombocytopenia and severe thrombocytopenia in the initially reduced-dose group were significantly lower than in the standard-dose group (p < 0.05). At the standard dose, the median linezolid trough concentration (C_min) just before hemodialysis was 49.5 mg/L, and C_min at the reduced doses of 300 mg every 12 h and 600 mg every 24 h were 20.6 mg/L and 6.0 mg/L, respectively. All five episodes underwent TDM in the standard-dose group required dose reduction to 600 mg per day. Our findings indicate that initial dose reduction should be implemented to reduce the risk of linezolid-induced thrombocytopenia among hemodialysis patients.

External Evaluation of Population Pharmacokinetics and Pharmacodynamics in Linezolid-Induced Thrombocytopenia: The Transferability of Published Models to Different Hospitalized Patients

BACKGROUND

The objective of this study was to perform an external evaluation of published linezolid population pharmacokinetic and pharmacodynamic models, to evaluate the predictive performance using an independent data set. Another aim was to offer an elegant environment for display and simulation of both the concentration and platelet count after linezolid administration.

METHODS

We performed a systematic literature search in PubMed for all studies evaluating the population pharmacokinetic and pharmacodynamic parameters of linezolid in patients and selected the models to be used for the external validation. The bias of predictions was visually evaluated by plotting prediction errors (PEs) and relative PEs. The precision of prediction was evaluated by calculating the mean absolute error (MAE), root mean squared error (RMSE), and mean relative error (MRE).

RESULTS

Three articles (models A, B, and C) provided linezolid-induced platelet dynamic models using population pharmacokinetic and pharmacodynamic modeling approaches. The PE and relative PE of both linezolid concentrations and platelet counts for models A and C showed similar predictive distributions. With respect to the prediction accuracy of total linezolid concentration, the MAE, RMSE, and MRE of population prediction values for model C was the smallest. The comparison of the MAE, RMSE, and MRE of patient-individual prediction values for the 3 pharmacodynamic models revealed no large differences.

CONCLUSIONS

We confirmed the transferability of published population pharmacokinetic and pharmacodynamic models and showed that they were suitable for extrapolation to other hospitals and/or patients. This study also introduced application software based on model C for the therapeutic drug monitoring of linezolid.

A case of COVID-19 diagnosed with favipiravir-induced drug fever based on a positive drug-induced lymphocyte stimulation test

As of October 2020, there is still no specific drug to treat COVID-19 as it rages worldwide. Favipiravir, indicated for the treatment of new and re-emerging influenza infections, has been suggested to be effective against SARS-CoV-2, although this is not yet fully validated. We administered favipiravir to a 64-year-old female patient with COVID-19. Her symptoms resolved quickly after the start of treatment, with reduction of SARS-CoV-2 viral load, but she developed a fever again on day 12. Since the fever was relieved by discontinuation of favipiravir, and based on positive results with a drug-induced lymphocyte stimulation test, we diagnosed her with favipiravir-induced drug fever. A decrease in the serum concentration of favipiravir was observed along with resolution of the fever. The present case suggests that drug fever should be considered in the differential diagnosis of relapsing fever episodes in COVID-19 patients receiving favipiravir.

Proposal of initial and maintenance dosing regimens with linezolid for renal impairment patients

Background

Linezolid is administered as a fixed dose to all patients despite evidence of overexposure and thrombocytopenia in renal impairment. The aims of this study were to evaluate the risk of thrombocytopenia and the utility of therapeutic drug monitoring (TDM), and to propose alternate dosing regimens in patients with renal impairment.

Methods

We retrospectively reviewed patients ≥13 years old for whom serum linezolid trough concentration (C_min) was measured during linezolid treatment. Patients with episodes of infection were divided into groups by presence of renal impairment (RI group) or absence of renal impairment (non-RI group), and by use of C_min-based TDM (TDM group) or not (non-TDM group) during linezolid treatment.

Results

In the 108 patients examined by multivariable analyses, renal impairment was independently associated with increased risk of thrombocytopenia (OR 3.17, 95%CI 1.10–9.12) and higher C_min. Analysis of the utility of TDM in the RI group showed that clinical failure rate was significantly lower in the TDM subgroup than in the non-TDM subgroup. Furthermore, in the RI group, dosage adjustments were needed in 90.5% of the TDM subgroup. All episodes administered a reduced dose of 300 mg every 12 h in the RI group showed C_min ≥ 2.0 mg/L. Additional analysis of 53 episodes in which C_min was measured within 48 h after starting administration showed that the initial standard dose for 2 days was sufficient to rapidly reach an effective therapeutic concentration in the RI group.

Conclusions

Empirical dose reduction to 300 mg every 12 h after administration of the initial fixed dose for 2 days and C_min-based TDM may improve safety outcomes while maintaining appropriate efficacy among patients with renal impairment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40360-021-00479-w.

Evaluation of SARS-CoV-2 neutralizing antibodies using a vesicular stomatitis virus possessing SARS-CoV-2 spike protein

Background

SARS-CoV-2 is a novel coronavirus that emerged in 2019 and is now classified in the genus Coronavirus with closely related SARS-CoV. SARS-CoV-2 is highly pathogenic in humans and is classified as a biosafety level (BSL)-3 pathogen, which makes manipulating it relatively difficult due to its infectious nature.

Methods

To circumvent the need for BSL-3 laboratories, an alternative assay was developed that avoids live virus and instead uses a recombinant VSV expressing luciferase and possesses the full length or truncated spike proteins of SARS-CoV-2. Furthermore, to measure SARS-CoV-2 neutralizing antibodies under BSL2 conditions, a chemiluminescence reduction neutralization test (CRNT) for SARS-CoV-2 was developed. The neutralization values of the serum samples collected from hospitalized patients with COVID-19 or SARS-CoV-2 PCR-negative donors against the pseudotyped virus infection evaluated by the CRNT were compared with antibody titers determined from an enzyme-linked immunosorbent assay (ELISA) or an immunofluorescence assay (IFA).

Results

The CRNT, which used whole blood collected from hospitalized patients with COVID-19, was also examined. As a result, the inhibition of pseudotyped virus infection was specifically observed in both serum and whole blood and was also correlated with the results of the IFA.

Conclusions

In conclusion, the CRNT for COVID-19 is a convenient assay system that can be performed in a BSL-2 laboratory with high specificity and sensitivity for evaluating the occurrence of neutralizing antibodies against SARS-CoV-2.

Monitoring of viral load by RT-PCR caused decision making to continue ECMO therapy for a patient with COVID-19

Most patients with coronavirus disease 2019 (COVID-19) have just only mild symptoms, but about 5% are very severe. Although extracorporeal membranous oxygenation (ECMO) is sometimes used in critically patients with COVID-19, ECMO is only an adjunct, not the main treatment. If the patient's condition deteriorates and it is determined to be irreversible, it is necessary to decide to stop ECMO. A 54-year-old man was admitted on day 6 of onset with a chief complaint of high fever and cough. Computed tomography (CT) showed a ground glass opacity in both lungs, and reverse transcription-polymerase chain reaction (RT-PCR) diagnosed COVID-19. He was admitted to the hospital and started to receive oxygen and favipiravir. After that, his respiratory condition deteriorated, and he was intubated and ventilated on day 9 of onset, and ECMO was introduced on day 12. Two days after the introduction of ECMO, C-reactive protein (CRP) increased, chest X-p showed no improvement in pneumonia, and PaO2/FiO2 decreased again. As D-dimer rose and found a blood clot in the ECMO circuit, we had to decide whether to replace the circuit and continue with ECMO or stop ECMO. At this time, the viral load by RT-PCR was drastically reduced to about 1/1750. We decided to continue ECMO therapy and replaced the circuit. The patient's respiratory status subsequently improved and ECMO was stopped on day 21 of onset. In conclusion, viral load measurement by RT-PCR may be one of the indicators for promoting the treatment of severe COVID-19 patients.

Proactive infectious disease consultation at the time of blood culture collection is associated with decreased mortality in patients with methicillin-resistant Staphylococcus aureus bacteremia: A retrospective cohort study

In most existing studies on the impact of infectious disease (ID) specialty care on bloodstream infections, ID consultations were started upon request or mandatory after notification of positive blood cultures; however, initial antibiotic therapy had already been administrated at that time by attending physicians. This study aimed to assess the impact of early ID consultation at the time of blood culture collection on therapeutic management and outcome of methicillin-resistant Staphylococcus aureus (MRSA) bacteremia. This retrospective cohort study investigated all patients with MRSA bacteremia (MRSAB) from 2011 to 2018. Proactive ID consultations were available 24 h per day, 7 days per week and obtained upon request by attending physicians, and patients were classed as having early ID consultation (at the time of blood culture collection) or late ID consultation (after notification of positive blood cultures), or none. A total of 55 first MRSAB episodes were included. In the ID consultation group, a significantly higher proportion of patients were treated for more than 14 days, and significantly more echocardiography and follow-up blood cultures were performed. Moreover, patients in the ID consultation group were hospitalized for a significantly shorter period overall. With respect to cost, we noted a possible association between ID consultation and lower hospital charges. Furthermore, relative to late ID consultation, patients receiving early ID consultation were more likely to receive appropriate empirical therapy and had significantly lower all-cause in-hospital mortality (odds ratio, 0.034; 95% confidence interval [CI], 0.0002-0.51; p = 0.015) and long-term mortality (hazard ratio, 0.17; 95% CI, 0.033-0.83; p = 0.028).

Pharmacokinetics and pharmacodynamics of daptomycin in a clinical setting

We investigated achievement of a target 24-h area under the concentration-time curve to minimum inhibitory concentration ratio (AUC/MIC) ≥666 and the factors influencing this ratio in patients who received daptomycin (DAP) for infectious disease treatment in a clinical setting. The target AUC/MIC was obtained in 6 patients (35.3%) at a 4-6 mg/kg dose (Group_{_4-6 mg/kg}) and in 4 (18.2%) at a >6 mg/kg dose (Group_{_>6 mg/kg}). There was a significant difference in clearance of DAP (CL_{_DAP}) between these groups, but no other difference in characteristics. Multiple linear regression analysis was performed for prediction of AUC ≥666 based on patient factors and the presence or absence of sepsis. In a stepwise analysis, serum creatinine (SCr) was a significant predictor of AUC, but this parameter explained only 13% of the variance in achievement of the target AUC. These results show that the target AUC/MIC may or may not be achieved at the doses used in Group_{_4-6 mg/kg} and Group_{_>6 mg/kg}. Receiver operating characteristic analysis suggested that a CL_{_DAP} >0.450 L/hr may lead to failure to reach the target AUC/MIC. Therefore, regardless of dose, the efficacy of DAP should be monitored closely to prevent failure of infectious disease treatment, particularly because therapeutic drug monitoring of DAP is limited by difficulty measuring the DAP serum concentration at many medical facilities. Our findings are preliminary, and a further study is required to identify factors that increase CL_{_DAP} and to enable dose adjustment of DAP.

Prostate abscess caused by Nocardia farcina

Nocardia farcinica usually infects the respiratory tract and can sometimes cause central nervous system infections; however, it rarely infects the prostate. Here we report the first case of N. farcinica detected in the purulence specimen drained from a prostate abscess. A 70-year-old Japanese male receiving steroid and cyclosporine treatment came to our department with chief complaint of turbid urine. Computed tomography revealed a low-density lesion in his prostate. Antibiotic administration and prostatic drainage were effective. N. farcinica was detected in the cultures of urine and prostatic drainage purulence specimens. Nocardiosis should be included in the differential diagnosis in immunosuppressive patients with prostate abscess.

Bacteremia caused by Slackia exigua: A report of two cases and literature review

Slackia exigua is an obligate anaerobic coccobacillus associated with dental infection, but rarely causes extraoral infection. We report two cases of monomicrobial bacteremia caused by S. exigua isolated from two institutions. The first case involved community-acquired bacteremia associated with pleural empyema in a 69-year-old man. The second case involved hospital-acquired bacteremia secondary to postoperative intra-abdominal abscess in a 73-year-old man with primary intestinal diffuse large B-cell lymphoma. S. exigua was finally identified by 16S ribosomal RNA gene sequencing analyses in both cases. In the first case, our attempts to identify the organism using commercial identification kits for anaerobes resulted in inaccurate identification as Gemella morbillorum. However, S. exigua was promptly identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry in the second case. The epidemiology and clinical characteristics of S. exigua extraoral infection remain unclear because of the limitations in accurate identification and because only 19 cases of extraoral S. exigua infection have been reported previously, including four cases of bacteremia. Physicians should focus on this species, which can cause community-acquired infections and spread via various routes even in patients with no comorbidities. Further studies are needed to clarify the clinical characteristics of extraoral S. exigua infections.

Congenital tuberculosis in an extremely preterm infant and prevention of nosocomial infection

Congenital tuberculosis is a rare disease, especially in non-endemic countries. We present a preterm infant who developed congenital tuberculosis in a neonatal intensive care unit (NICU). The male patient, weighing 1140 g was born by cesarean section at 26 weeks gestation. The baby's respiratory condition suddenly deteriorated at 18 days old, and he was diagnosed with congenital tuberculosis after Gram stain revealed "ghost bacilli" in his tracheal aspirate. The mother, who was born in an endemic country, had fever with unknown cause during labor and was diagnosed with miliary tuberculosis after the infant was diagnosed. Both were successfully treated for tuberculosis with a four-drug regimen. The genotyping profiles of Mycobacterium tuberculosis were identical in both mother and baby based on variable number of tandem repeat (VNTR) analysis. The lineage was considered to be East-African Indian. To prevent nosocomial infection in the NICU, 23 potentially exposed infants received isoniazid for 2 months. Two infants showed a transient liver enzyme elevation that seemed to be due to isoniazid. For 10 months after the incident, there were no infants and medical staff who developed tuberculosis. Although the incidence of tuberculosis has steadily decreased in Japan, the percentage of foreign-born individuals has increased yearly, especially those of reproductive age. The evaluation of active tuberculosis should be considered in pregnant women with unexplained fever, history of tuberculosis, or emigration from high-burden areas.

Multimodal imaging findings in an adult case of Swyer-James-MacLeod syndrome

Swyer‐James‐MacLeod syndrome (SJMS) is an uncommon obliterative lung disease that is radiologically characterized by hyperlucency of a part of or the entire lung. A 33‐year‐old man presented to our hospital for chest tightness. A chest X‐ray revealed unilateral hyperlucency of left lower lung, and contrast‐enhanced computed tomography (CT) of the chest disclosed a hyperlucent left lung without vascularity. Three‐dimensional CT reconstruction and ventilation–perfusion scan findings were concordant with SJMS. We herein report a case of SJMS in a patient who showed the characteristic multimodal imaging findings.