Clinical and microbiological characteristics of Ruminococcus gnavus bacteremia and intra-abdominal infection.

OBJECTIVES: Ruminococcus gnavus is a rare human pathogen, and clinical data on R. gnavus infection are insufficient. This retrospective study aimed to investigate the clinical characteristics of R. gnavus infections. METHODS: This study included 13 cases of bacteremia and three cases of non-bacteremia infections caused by R. gnavus. We evaluated the patient data, infection source, clinical outcomes, and antimicrobial susceptibility of R. gnavus isolates for these cases. RESULTS: The median age of patients was 75 years (range 47-95), and eight patients were female. Twelve cases were presumed to have an intra-abdominal infection source, and the remaining four cases had an unknown infection source. The most common underlying conditions were immunosuppression (seven cases), solid tumors (seven cases), and history of gastrointestinal surgery (five cases). Thirteen patients exhibited gastrointestinal problems (dysfunction, bleeding, intra-abdominal infection, or inflammation). Multiple pathogens were observed in six cases, and fatal outcomes were recorded in three cases. Antimicrobial susceptibility data were available for eight isolates, all of which exhibited low minimum inhibitory concentrations to penicillin (≤0.03 µg/mL), ampicillin-sulbactam (≤0.5 µg/mL), piperacillin-tazobactam (≤4 µg/mL), and metronidazole (≤0.5-1 µg/mL). CONCLUSION: Ruminococcus gnavus is frequently associated with an intra-abdominal infection source, and treatment strategies should consider the possibility of multiple pathogens.

Immunogenicity and safety of influenza vaccine in patients with lung cancer receiving immune checkpoint inhibitors: A single-center prospective cohort study.

INTRODUCTION: Patients with lung cancer have a high risk of influenza complications. International guidelines recommend annual influenza vaccination for patients with cancer. Immune checkpoint inhibitors (ICIs) are progressively used to treat lung cancer. Data regarding immunogenicity and safety of influenza vaccine are limited in patients with lung cancer receiving ICIs; therefore, we conducted this single-center, prospective observational study in the Japanese population. METHODS: Patients with lung cancer receiving ICIs and influenza immunization were enrolled. Blood samples were collected from patients for serum antibody titer measurement pre- and 4 ± 1 weeks post-vaccination. The primary endpoint was seroprotection rate (sP) at 4 ± 1 weeks post-vaccination. The secondary endpoints were geometric mean titer (GMT), mean fold rise, seroresponse rate (sR), seroconversion rate (sC), and immune-related adverse events (irAEs), defined as adverse effects caused by ICI administration, 6 months post-vaccination. RESULTS: Influenza vaccination in the 23 patients included in the immunogenicity analyses significantly increased GMT for all strains, and sP, sR, and sC were 52%-91%, 26%-39%, and 26%-35%, respectively. In the 24 patients included in the safety analyses, 7 (29%) and 5 (21%) patients exhibited systemic and local reactions, respectively. Only one patient (4%) (hypothyroidism, grade 2) showed post-vaccination irAEs. CONCLUSIONS: Overall, influenza vaccination in patients with lung cancer receiving ICIs showed acceptable immunogenicity and safety, thus supporting annual influenza vaccination in this population.

Catheter-related bloodstream Mycobacterium wolinskyi infection in an umbilical cord blood transplant recipient: a case report.

BACKGROUND: Catheter-related bloodstream infection (CRBSI), caused by rapidly growing mycobacteria (RGM), is a rare infectious complication in hematopoietic stem cell transplant (HSCT) recipients and can often be misdiagnosed as Gram-positive rod (GPR) bacteremia. CASE PRESENTATION: We present a case of CRBSI caused by Mycobacterium wolinskyi, a rare RGM, in a 44-year-old female patient who received an umbilical cord blood transplant. CONCLUSIONS: Rapidly growing mycobacteria can stain as GPRs and may grow in routine blood culture media after 3-4 days of incubation. These features are not widely known to clinicians, and acid-fast staining is therefore recommended when unidentifiable GPRs are detected in blood cultures, especially in immunocompromised patients, such as those with hematologic malignancies or intravascular devices.

Potential for false-positive results with quantitative antigen tests for SARS-CoV-2: A case of a child with acute respiratory infection.

The quantitative antigen test based on the chemiluminescent enzyme immunoassay for SARS-CoV-2 has been used in international airports for quarantine in Japan. While cases of false-positive rapid antigen tests for SARS-CoV-2 were reported, false-positive cases of the quantitative antigen test with clinical information are rare. Here, we report a case of acute respiratory infection whose quantitative antigen test for SARS-CoV-2 was suspected to be false positive. A 9-month-old boy who presented with fever and rhinorrhea was admitted to our hospital under the Quarantine Act. He was diagnosed with COVID-19 based on the quantitative antigen test for SARS-CoV-2 performed at the quarantine station. None of the accompanying family members were positive for COVID-19. Nucleic acid amplification tests (NAAT) for SARS-CoV-2 were all negative, and multiplex polymerase chain reaction detected human rhinovirus or enterovirus infection. This case suggests that the results of the quantitative antigen test should be interpreted together with clinical information, and NAAT should be performed when false-positive results are suspected to avoid unnecessary isolation.

[THE CORRELATION OF ALLERGY SPECIFIC IGE MEASUREMENT REAGENT IMMNOCAP, ALASTAT, AND ORITON IGE].

BACKGROUND: The reagent which is available for single allergenic tests is Oriton IgE, ImmnoCAP, Alastat in Japan. No study has investigated the correlations of Oriton IgE and ImmnoCAP or Alastat, and, used for specific IgE antibody testing. METHOD: Six frequently tested allergens (dust mite, cedar pollen, dog dander, egg white, milk, and candida) were measured by three methods, and Spearman rank correlation coefficient and class-judged agreement were evaluated. Furthermore, we did the evaluation like other 2 methods when we made small short sample volumes of Oriton IgE. RESULT: As for the examination result of Oriton IgE and ImmnoCAP or Alastat, constant correlation was confirmed. However, the tendency was a different result by assay method and an allergenic item. No significant differences were observed in the results of the Oriton IgE test when standard sample volumes and small short sample volumes were used. CONCLUSION: These comparison results help us to understand each characteristic and select an optimal test method. In addition, it can be inferred that it is beneficial to choose tests requiring small sample volumes in pediatric patients.

Clinical characteristics and drug susceptibility patterns of Corynebacterium species in bacteremic patients with hematological disorders.

The aim of this study was to clarify the clinical and microbiological characteristics of Corynebacterium bacteremia in hematological patients. We retrospectively reviewed the medical records of patients with Corynebacterium bacteremia from April 2013 to June 2018. The causative Corynebacterium species were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Drug susceptibility tests were performed using the broth microdilution method recommended by the Clinical and Laboratory Standards Institute. In total, 147 cases of Corynebacterium bacteremia were identified during the study period. Corynebacterium striatum was the most frequent pathogen. Catheter-related bloodstream infection was diagnosed in 19.7% of all patients, and moderate/severe oral or severe gastrointestinal mucosal impairment was detected in 19.7%. Polymicrobial infection was found in about 20% of cases, with Enterococcus faecium being the most frequent isolate. The overall 30-day mortality was 34.7% (51/147). Multivariate analysis showed that E. faecium co-infection (odds ratio (OR) 9.3; 95% confidence interval (CI) 2.1-40), systemic corticosteroids (OR 3.6; 95% CI 1.4-8.9), other immunosuppressive drugs (OR 0.32; 95% CI 0.13-0.76), and a Pitt bacteremia score ≥4 (OR 12; 95% CI 3.9-40) were significant risk factors for overall 30-day mortality. The drug susceptibility rates for beta-lactam antimicrobial agents were quite low. All isolates were susceptible to glycopeptides and linezolid. However, some C. striatum isolates were resistant to daptomycin. Corynebacterium bacteremia can occur in the presence of several types of mucosal impairment. Our drug susceptibility data indicate that Corynebacterium bacteremia in hematological patients could be treated by glycopeptides or linezolid.

Low cut-off value of serum (1,3)-beta-D-glucan for the diagnosis of Pneumocystis pneumonia in non-HIV patients: a retrospective cohort study.

BACKGROUND: Non-human immunodeficiency virus (HIV) Pneumocystis pneumonia (PCP) is a fulminant disease with an increasing incidence. The serum beta-D-glucan (BDG) assay is used as an adjunct to the diagnosis of PCP; however, the cut-off value for this assay is not well-defined, especially in the non-HIV PCP population. Therefore, we aimed to identify the assay cut-off value for this population. METHODS: In this retrospective observational study, we reviewed the medical records of all patients (≥ 18 years old) with clinical suspicion of PCP who underwent evaluation of respiratory tract specimens between December 2008 and June 2014 at Kameda Medical Center. We created a receiver operating characteristic curve and calculated the area under the curve to determine the cut-off value for evaluating the inspection accuracy of the BDG assay. RESULTS: A total of 173 patients were included in the study. Fifty patients showed positive results in specimen staining, loop-mediated isothermal amplification assay, and polymerase chain reaction test, while 123 patients showed negative results. The receiver operating characteristic analyses suggested that the BDG cut-off level was 8.5 pg/mL, with a sensitivity and specificity of 76% and 76%, respectively. CONCLUSIONS: The Wako-BDG cut-off value for the diagnosis of non-HIV PCP is 8.5 pg/mL, which is lower than the classical cut-off value from previous studies. Clinicians should potentially consider this lower BDG cut-off value in the diagnosis and management of patients with non-HIV PCP. TRIAL REGISTRATION:  The participants were retrospectively registered.

A case of Salmonella osteomyelitis mimicking a malignant tumor of the humerus in an immunocompetent adult patient identified using broad-range polymerase chain reaction with sequencing of a biopsied specimen.

BACKGROUND: Salmonella infections are associated with gastroenteritis, enteric fever, bacteremia, focal infection, and chronic carrier state. Cases of Salmonella osteomyelitis are uncommon and mainly occur in individuals with immunosuppressive conditions. Herein, we report a case of Salmonella osteomyelitis that required differentiation from malignancy in an immunocompetent adult patient. CASE PRESENTATION: A 31-year-old previously healthy male truck driver presented with a 2-week history of pain in his left upper arm. He had fallen off the back of a truck 2 months previously and injured the left side of his body. He also had bloody diarrhea and fever. Computed tomography and magnetic resonance imaging revealed a lesion that appeared to be a bone tumor in the left humerus, and the patient was referred to our cancer center from another clinic. Culture of a biopsy specimen of the left humerus was negative; however, the consensus sequence in broad-range polymerase chain reaction (PCR) showed the highest similarity to the 16S rRNA gene of Salmonella enterica subspecies enterica. Curettage of the left humerus was performed, and the patient was administered levofloxacin for 6 weeks. He recovered left arm function and had no recurrence during 2 months of follow-up. CONCLUSIONS: When the culture of blood or biopsy specimens is negative in situations wherein a specific infection is suspected, broad-range PCR with sequencing should be considered to determine the causative organism.

Early diagnosis of Cryptococcus neoformans var. grubii meningitis using multiplex PCR assay in an immunocompetent patient.

Cryptococcosis is an invasive fungal infection that mainly affects the lungs and central nervous system. While patients with cell-mediated immunodeficiency are at high risk of developing cryptococcosis, there have been increasing reports of cryptococcosis in immunocompetent individuals with no underlying conditions. Herein, we report a case of cryptococcal meningitis in a 55-year-old apparently immunocompetent man with a history of heavy alcohol consumption. Although the patient was initially treated for tuberculous meningitis and varicella-zoster virus induced vasculopathy due to a history of exposure to tuberculosis and a presence of stroke, a multiplex polymerase chain reaction (PCR) assay of cerebrospinal fluid (CSF) identified Cryptococcus species unexpectedly, enabling swift treatment and a favorable clinical outcome. The multiplex PCR assay, which can identify multiple pathogens simultaneously and instantly, may lead to early diagnosis and treatment by detecting unanticipated pathogens. Furthermore, the strain was identified through multilocus sequence typing (MLST) analysis as Cryptococcus neoformans var. grubii, Sequence Type 5, molecular type: VNI. Although simplified microbial identification techniques such as mass spectrometry have recently been developed, molecular biological assays are still essential for the accurate identification of infectious strains.

First case report of thyroid abscess caused by Helicobacter cinaedi presenting with thyroid storm.

BACKGROUND: Helicobacter cinaedi is a microaerobic Gram-negative spiral-shaped bacterium that causes enteritis, cellulitis, and bacteremia in both immunocompromised and immunocompetent patients. While there have been increasing numbers of reported H. cinaedi infections recently, there has been no thyroid abscess case caused by H. cinaedi presenting with thyroid storm. CASE PRESENTATION: A 50-year-old Japanese man presented with a 9-day history of high fever associated with palpitations, dry cough, and chronic diarrhea. The patient had a history of Basedow's disease that had been treated with thiamazole in the past. During the current episode, the patient was diagnosed with thyroid storm and treated accordingly. The blood culture taken on admission was positive for H. cinaedi. This finding was confirmed by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOFMS). A systemic computed tomography (CT) scan revealed a thyroid abscess as the site of infection and cause of the bacteremia. The 16S rRNA gene sequencing identified the pathogen of thyroid abscess as H. cinaedi. Clinical symptoms and laboratory data normalized on admission day 7 after treatment with both effective antibiotics and antithyroid drugs. CONCLUSIONS: The case study described a patient with a history of Basedow's disease that presented with a thyroid abscess caused by H. cinaedi with symptoms similar to those of thyroid storm. While this bacterium has been implicated in other infections, we believe this is the first time the bacteria has been documented to have caused a thyroid abscess.

Lactococcus lactis cholangitis and bacteremia identified by MALDI-TOF mass spectrometry: A case report and review of the literature on Lactococcus lactis infection.

Lactococcus lactis is a rare causative organism in humans. Cases of L. lactis infection have only rarely been reported. However, because it is often difficult to identify by conventional commercially available methods, its incidence may be underestimated. We herein report the case of a 70-year-old man with cholangiocarcinoma who developed L. lactis cholangitis and review previously reported cases of L. lactis infection. Our case was confirmed by matrix-assisted desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). This case shows L. lactis is a potential causative pathogen of cholangitis and that MALDI-TOF MS can be useful for the rapid and accurate identification of L. lactis infection. We searched the literature for published case reports on cholangitis and any other infections caused by L. lactis, and thereby identified 36 cases, including our case. At least 66.7% (n = 24) of the cases had significant underlying conditions; 15 of the cases involved patients with an immunocompromised status. At least 41.7% (n = 15) had a significant food consumption history, such as the consumption of unpasteurized dairy products. The clinical sources of L. lactis were diverse and endocarditis was the most common diagnosis (n = 8), followed by hepatobiliary infection (n = 6), central nervous system infection (n = 5), and peritonitis (n = 4). The prognosis was favorable in most cases.

Catheter-related bloodstream infection by Microbacterium paraoxydans in a pediatric patient with B-cell precursor acute lymphocytic leukemia: A case report and review of literature on Microbacterium bacteremia.

Microbacterium species are coryneform gram-positive rods that are widely distributed in the environment and have been recently recognized as rare pathogens in humans. However, information about the epidemiologic and clinical characteristics of Microbacterium species is scarce. We herein reported an 11-year-old girl with acute leukemia who was found to have catheter-related bloodstream infection in her neutropenic phase. Gram-positive bacilli repeatedly grew on the blood cultures and were later confirmed by 16S rRNA analysis as Microbacterium paraoxydans. A literature review found available clinical courses in 21 cases (7 pediatric cases) of Microbacterium spp. bacteremia. Our case and those in literature suggested that Microbacterium spp. bacteremia often occurs in patients with indwelling central venous catheters; the literature review further suggested that removal of central venous catheters is required in most cases and that 16S rRNA sequence was useful in identifying in detail the species of Microbacterium.

Legionella pneumonia appeared during hospitalization in a patient with hematological malignancy confirmed by sputum culture after negative urine antigen test.

Legionella pneumophila is recognized as a common causative organism for community-acquired pneumonia, but it is rarely a causative organism for hospital-acquired pneumonia, except in cases of hospital outbreak. Recently, most of the Legionella cases have been diagnosed using the urine antigen test. However, this test can reliably detect only L. pneumophila serogroup 1. Here we report a 63-year-old male patient who was recently diagnosed with acute leukemia and treated with chemotherapy and who developed pneumonia on hospital day 8 during the nadir phase. He was later diagnosed with Legionella pneumonia by culture despite a negative urine antigen test. This case suggests that Legionella pneumonia is an important differential diagnosis for pneumonia in inpatients in the early phase of hospitalization and that when Legionella infection is clinically suspected, culture using selective media or molecular tests should be performed even if the urine antigen test is negative.

Effects of sperm direction in Piezo-ICSI on oocyte survival, fertilization, embryo development and implantation ability in humans: A preliminary study.

AIMS: The objective of this study was to investigate the effect of the head-first or tail-first injection of sperm into the cytoplasm by Piezo-ICSI (PICSI) on oocyte survival, fertilization, embryo development and implantation ability in humans. METHODS: We retrospectively investigated 632 mature oocytes retrieved from 152 infertile patients who attended our PICSI-ET program at the Niji Clinic between October 2010 and January 2014. Of these, 342 mature oocytes retrieved from 75 patients were injected with sperm head first, and 290 mature oocytes retrieved from 77 patients were injected with sperm tail first into the cytoplasm. The rates of oocyte survival, fertilization, good-quality day-3 embryos, pregnancy, implantation and live birth were evaluated in both groups. RESULTS: There were no differences among the two groups with respect to survival, fertilization, good-quality day-3 embryos, pregnancy, implantation and live birth rates. CONCLUSION: Sperm direction (i.e., head first or tail first) does not influence the outcome of PICSI in human oocytes, including oocyte survival, fertilization, embryo development and implantation ability. These findings contribute to an understanding of factors that influence the success of human intracytoplasmic sperm injection (ICSI) techniques.

Pyelonephritis with bacteremia caused by Listeria monocytogenes: A case report.

Listeria monocytogenes is a well-known cause of meningitis, colitis, and bacteremia; however, obstructive pyelonephritis caused by L. monocytogenes has never been reported. We herein report on a 90-year-old Japanese woman with obstructive pyelonephritis and bacteremia due to uterus carcinoma invading the ureter. She was admitted to our hospital complaining of fever and chills, and her physical examination revealed left costovertebral angle tenderness. Computed tomography showed hydronephrosis and complete ureteral obstruction due to tumor invasion. Blood and urine cultures upon nephrostomy revealed the growth of L. monocytogenes. We treated the patient with two weeks of intravenous ampicillin and an additional one-week treatment of oral sulfamethoxazole/trimethoprim. This case shows the importance to recognize L. monocytogenes as a potential causative agent of urinary tract infection.

A 10-year profile of enterococcal bloodstream infections at a tertiary-care hospital in Japan.

OBJECTIVES: The first aim of this study is to characterize the epidemiology of enterococcal bloodstream infections (BSIs) at a Japanese tertiary-care hospital. The second aim is to identify predictive factors for 30-day mortality. METHODS: We conducted a single center retrospective observational study. All patients with enterococcal BSI between 2005 and 2014 were enrolled. Univariate and multivariate analysis were performed to evaluate predictive factors for 30-day mortality. RESULTS: A total of 410 patients with enterococcal BSI were enrolled. Enterococcus faecalis was identified in 200 patients (48.8%) and Enterococcus faecium in 124 patients (30.2%). Isolates were susceptible to ampicillin and vancomycin (67.3% and 97.8%, respectively). Isolates that were not susceptible to vancomycin were either Enterococcus casseliflavus or Enterococcus gallinarum. All strains of E. faecalis and 10.8% of E. faecium strains were susceptible to ampicillin. Thirty-day mortality was 24.8%. Predictive factors for 30-day mortality were Charlson Comorbidity Index (CCI) 1-2 (adjusted odds ratio [OR] 6.07, 95% confidence interval [CI]: 1.22-30.2), CCI 3-4 (adjusted OR 8.79, 95% CI: 1.70-45.4), CCI ≥5 (adjusted OR 17.6, 95% CI: 3.52-88.2), E. faecium bacteremia (adjusted OR 2.19, 95% CI: 1.27-3.76), Pitt Bacteremia Score (PBS) ≥5 (adjusted OR 15.1, 95% CI: 6.41-35.6), and source control (adjusted OR 0.39, 95% CI: 0.22-0.72). CONCLUSION: Vancomycin-resistant strains of E. faecalis and E. faecium were not seen in this cohort. In addition, all strains of E. faecalis and 10.8% of E. faecium strains were susceptible to ampicillin. Predictive factors for 30-day mortality were CCI score, E. faecium bacteremia, PBS score, and source control.

Clinical Features of Community-Acquired Helicobacter cinaedi Bacteremia.

BACKGROUND: There are growing numbers of reports concerning the clinical and pathological features of Helicobacter cinaedi (H. cinaedi) bacteremia; however, few reports have discussed the features of this condition in healthy individuals. PATIENTS AND METHODS: A retrospective observational study was conducted at a Japanese tertiary care hospital to assess the clinical features of community-acquired H. cinaedi. All patients in whom H. cinaedi was isolated between January 2009 and March 2014 were identified from the hospital database. RESULTS: Of the 28 patients included in the study, 12 had community-acquired H. cinaedi bacteremia. The most common clinical feature was cellulitis (n = 17). However, nearly half of the patients with healthcare-associated or nosocomial-associated bacteremia displayed no symptoms with the exception of fever. Most patients were successfully treated with a 14-day regime of third-generation cephalosporins or tetracycline. CONCLUSIONS: Our results show that H. cinaedi infections are quite common in immunocompetent community-dwelling individuals.

Bloodstream infections caused by Streptococcus anginosus group bacteria: A retrospective analysis of 78 cases at a Japanese tertiary hospital.

OBJECTIVES: To investigate the characteristics of Streptococcus anginosus group (SAG) bacteremia in recent years, we conducted a retrospective cohort study and compared its findings with the data from previous studies. METHODS: All patients with positive blood cultures from May 2005 to September 2014 in a tertiary care center with 925 beds were included. RESULTS: There were 78 cases of SAG bacteremia (51 cases men; median age, 68 years) during the study period. The most common comorbidities were solid tumors in 32.1% of the patients. The most common infection source was hepatobiliary in one-third of all cases. Other infection sites included the following: intra-abdominal (12.8%), thoracic (10.3%), musculoskeletal (9%), urinary tract (7.7%), soft tissues (7.7%), and cervicofacial (6.4%). Susceptibility to penicillin, clindamycin and erythromycin were 100% (78/78), 95% (70/74) and 85% (39/46), respectively. Surgery along with systemic antibiotic treatment was administered in 53% of the cases. In-hospital mortality was 14.1%. CONCLUSION: The clinical sources of the SAG bacteria were diverse, and hepatobiliary infection was the most common source of infection. In more than half of the patients, surgical treatment was performed. Susceptibility to penicillin was 100%, but susceptibility to erythromycin was lower than that reported in previous studies.

[Acute Pyelonephritis and Candidemia Due to Candida lusitaniae: A Case Report].

Although candiduria is becoming increasingly common among hospitalized patients, Candida lusitaniae is a rare pathogen that account for less than 1% of Candida species isolated from urine. Ascending pyelonephritis and candidemia due to Candida species are uncommon complications. We report herein on a case of acute pyelonephritis and candidemia due to C. lusitaniae. A 66-year-old man presented with a high fever during hospitalization at our hospital following septic shock due to ischial osteomyelitis treated with tazobactam/piperacillin for 29 days. We suspected acute pyelonephritis, and urinary Gram staining showed only yeasts and leucocytes. The next day, blood culture and urine culture tested positive and showed yeast-like fungi. We diagnosed acute pyelonephritis and candidemia due to Candida species and started treatment with fluconazole. C. lusitaniae was identified on the hospital day 34 and treated with fluconazole for 14 days. Candida albicans was the most prevalent species isolated from the urinary tract, however non-albicans Candida species have emerged and are now dominant because of the advent and increasing use of fluconazole. C. lusitaniae is a rare but important pathogen, that is generally susceptible to fluconazole and resistant to amphotericin B. It is necessary to choose an appropriately effective antifungal drug based on identification of the fungal species.