Clinical phenotype of anaerobic bacteremia unaccompanied by detectable abscess lesion: a 10-year retrospective, multicenter, observational-cohort study.

PURPOSE: Despite the importance of abscess lesions in clinical decisions regarding anaerobic bacteremia (AB), their impact on clinical characteristics remains unclear. Herein, we aimed to elucidate the clinical factors associated with AB that were unaccompanied by detectable abscess lesions during the initial phase of infection. METHODS: This was a multicenter retrospective observational study involving patients with culture-proven AB at six tertiary hospitals in Japan between January 2012 and March 2022. Data on clinical characteristics, laboratory and radiological findings were collected, and their associations with the absence of detectable abscess lesions were analyzed. RESULTS: In total, 393 participants were included. Abscess lesions were absent in 42.7% of the entire cohort and detectable in the remaining patients. No differences were identified in the malignancy, severity, or 30-day mortality between patients with and without detectable abscess lesions. Multivariate logistic regression analysis adjusted for age and the modified Charlson comorbidity score revealed that the immunosuppressive status (febrile neutropenia or corticosteroid use), C-reactive protein (CRP) level ≤9.8 mg/dL at onset, and the presence of gram-positive anaerobic rods (GPARs) were independently associated with AB unaccompanied by detectable abscess lesions [odds ratios (ORs) 3.24, 3.00, and 2.81, respectively; p < 0.05]. CONCLUSION: This study elucidated distinctive clinical and microbiological characteristics of AB unaccompanied by detectable abscess lesions, with relatively lower CRP elevation, immunosuppressive status, and GPARs as the causative anaerobes.

Comparison of the effectiveness of core genome multilocus sequence typing and polymerase chain reaction-based open reading frame typing in tracing nosocomial methicillin-resistant Staphylococcus aureus transmission.

INTRODUCTION: A clonal shift from staphylococcal cassette chromosome mec (SCCmec) type II/ST5 methicillin-resistant Staphylococcus aureus (MRSA) to SCCmec type IV/clonal complex (CC)1 MRSA has occurred rapidly in Japan. Our previous research in a geriatric hospital found SCCmec type IV/CC1 MRSA prevalence in long-term care wards. Due to intensive personal care requirements, frequent contact with healthcare providers can potentially cause unintentional nosocomial MRSA transmission. We performed polymerase chain reaction-based open reading frame typing (POT) and core genome multilocus sequence typing (cgMLST) to investigate the occurrence of nosocomial transmission and to compare the results of these methods. METHODS: POT and whole genome sequencing were performed in 83 MRSA isolates. Commercial automated software (Ridom SeqSphere+) was used to perform cgMLST. MRSA isolates with 0-8 allelic differences were considered related, and medical records were consulted in these cases. RESULTS: SCCmec type IV/CC1 MRSA was the most frequently detected clone (n = 56, 67.5 %), which was divided into 14 POT types, followed by SCCmec type I/ST8 (n = 9) and SCCmec type IV/ST8 (n = 8). Identical POT types were found across 7 of 11 wards. However, cgMLST analysis identified only three cases (six strains) of high genetic similarity, indicating nosocomial transmission; only one involved SCCmec type IV/CC1 (two strains). The mean allelic difference in the core genomes between strains with identical POT types in the same ward was 55.3 ± 22.0. CONCLUSIONS: The cgMLST method proved more effective for identifying nosocomial transmissions compared to POT, highlighting its utility in tracking MRSA spread in healthcare settings.

The evaluation of a rapid microfluidic immunofluorescence antigen test in detecting the infectiousness of COVID-19 patients.

BACKGROUND: A test-based strategy against coronavirus disease 2019 (COVID-19) is one of the measures to assess the need for isolation and prevention of infection. However, testing with high sensitivity methods, such as quantitative RT-PCR, leads to unnecessary isolation, whereas the lateral flow antigen test shows low sensitivity and false negative results. The purpose of this study was to evaluate the performance of the LumiraDx SARS-CoV-2 Ag test (Lumira Ag), a rapid microfluidic immunofluorescence method, in assessing infectivity. METHODS: This study was performed from March 2022 to July 2022. A pair of nasopharyngeal swab samples were obtained from each patient with mild COVID-19. One swab was used for Lumira Ag testing, and the other for quantitative RT-PCR testing and virus culture. RESULTS: A total of 84 patients were included in the study. Among them, PCR, Lumira Ag test, and virus culture indicated positivity for 82, 66, and 24 patients, respectively. When comparing the Lumira Ag test to virus culture, its sensitivity was 100.0% (24/24), specificity, 30.0% (18/60); positive predictive value, 36.3% (24/66); and negative predictive value (NPV), 100.0% (18/18). The positive sample for virus culture was observed until the ninth day from the onset of symptoms, while the Lumira Ag test was observed until day 11. CONCLUSIONS: The Lumira Ag test showed high sensitivity and NPV (100% each) compared to virus culture. A test-based strategy using the Lumira Ag test can effectively exclude COVID-19 infectiousness.

Epidemiological analysis and antimicrobial susceptibility profile of Gram-negative bacilli that cause bacteremia in Japan.

We investigated the epidemiology and antimicrobial susceptibility profiles of seven major Gram-negative bacilli (Escherichia coli, Klebsiella spp., Enterobacter spp., Pseudomonas aeruginosa, Acinetobacter spp., Stenotrophomonas maltophilia, and Bacteroides spp.) that caused bacteremia in Japan. We collected clinical information and isolates from patients aged 20 years or older who developed bacteremia during a year at three Japanese university hospitals and performed microbiological examination. In total, 628 cases were included, half of which were caused by E. coli (315 isolates). P. aeruginosa (56 isolates) was isolated most frequently among non-fermenting bacteria and 33 Bacteroides spp. were isolated. Mortality rates were the highest for P. aeruginosa (7-day, 16.1%; 30-day, 26.8%). The 7- and 30-day mortality rates ranged 3.8-9.0% and 8.3-17.6%, respectively, for Enterobacterales, and they were 15.2% each for Bacteroides spp. Regarding antimicrobial resistance, Enterobacterales and Acinetobacter spp. showed susceptibility to carbapenems and amikacin (98.0-100.0%). The susceptibility rates to ceftolozane/tazobactam ranged 82.4-99.0% for Enterobacterales and 92.9% for P. aeruginosa. More than 30.0% of E. coli isolates were resistant to fluoroquinolone. Extended-spectrum ß-lactamase (ESBL) producers were found in 21.0% of E. coli and approximately 80% of those were resistant to fluoroquinolones. The susceptibility of the 33 Bacteroides spp. to carbapenems, ampicillin/sulbactam, and piperacillin/tazobactam was 100.0%. Among the ESBL producers, blaCTX-M group 9 was the major subgroup in E. coli (77.3%), and blaCTX-M group 1 was detected in 18.2% of E. coli and 50.0% of Klebsiella spp. Continuous surveillance is needed to understand the epidemiology and consider appropriate therapeutic strategies.

Clinical evaluation of a fully automated and high-throughput molecular testing system for detection of influenza virus.

INTRODUCTION: We investigated the performance of the cobas® 6800 system and cobas SARS-CoV-2 & Influenza A/B, a fully automated molecular testing system for influenza viruses and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This enabled an assay in a batch of 96 samples in approximately 3 h. METHODS: An assay was performed using the cobas SARS-CoV-2 & Influenza A/B on the cobas 6800 system for samples collected in four facilities between November 2019 and March 2020 in our previous study. The results were compared with those obtained using the reference methods. RESULTS: Of the 127 samples analyzed, the cobas SARS-CoV-2 & Influenza A/B detected influenza A virus in 75 samples, of which 73 were positive using the reference methods. No false negative results were observed. The overall positive and negative percent agreement for influenza A virus detection were 100.0% and 96.3%, respectively. There were no positive results for the influenza B virus or SARS-CoV-2. CONCLUSION: The cobas 6800 system and cobas SARS-CoV-2 & Influenza A/B showed high accuracy for influenza A virus detection and can be useful for clinical laboratories, especially those that routinely assay many samples.

BioFire FilmArray Pneumonia Panel enhances detection of pathogens and antimicrobial resistance in lower respiratory tract specimens.

BACKGROUND: This study investigated the diagnostic utility of the BioFire FilmArray Pneumonia Panel (PN panel), an automated and multiplexed nucleic acid detection system that rapidly detects 26 pathogens (18 bacteria and eight viruses) and seven antimicrobial resistance markers in a single assay. METHODS: We analyzed the targets in lower respiratory tract specimens using the PN panel and compared the detection results with those of bacterial culture methods and antimicrobial susceptibility testing. RESULTS: Of the 57 samples analyzed, the PN panel detected 97 targets (84 bacteria, four viruses, and nine antimicrobial resistance markers). Detection of bacteria and antimicrobial resistance was three times greater than that of the bacterial culture (25 bacteria and two resistant isolates) against the targets available in the panel. The overall positive and negative percent agreements between the PN panel and culture methods for bacterial detection were 100.0% and 92.9%, respectively. Multiple pathogens were detected by the PN panel in 24 samples (42.1%), ranging from two pathogens in 11 samples (19.3%) to six pathogens in one sample (1.8%). The PN panel semiquantitatively detected higher copies (≥ 106 copies/mL) of bacterial targets if the bacteria were positive by the culture method. In contrast, the semiquantitative values obtained by the panel varied (104 to 107 ≤ copies/mL) among bacteria that were negative by the culture method. CONCLUSIONS: The PN panel enhanced the detection of pathogens and antimicrobial resistance markers in lower respiratory tract specimens.

Multicenter evaluation of molecular point-of-care testing and digital immunoassays for influenza virus A/B and respiratory syncytial virus in patients with influenza-like illness.

INTRODUCTION: Digital immunoassays (DIAs) and molecular point-of-care (POC) tests for influenza were recently developed. We aimed to evaluate and compare the positive rate with molecular POC tests and DIAs in detecting influenza virus A, B and respiratory syncytial virus (RSV). METHODS: A prospective observational study was conducted in 2019-2020. Nasopharyngeal swab samples were collected from adult outpatients with influenza-like illness who visited four hospitals and clinics in Japan. DIAs were performed at each facility. The clinical diagnosis was determined based on the findings of DIAs, history taking, and physical assessment. Molecular POC test and reverse transcription polymerase chain reaction (RT-PCR) were performed later. RESULTS: A total of 182 patients were evaluated. The positive rate for influenza virus with molecular POC test was significantly higher than that with DIAs (51.6% versus 40.7%, p = 0.046). In patients who tested positive for influenza virus with only molecular POC test, the presence of influenza virus was confirmed by RT-PCR. In a comparison between the patients who were positive for influenza virus with only molecular POC test and those with both molecular POC test and DIA, the percentage of patients who sought consultation within 18 h after the onset of symptoms was significantly higher in the molecular POC test only group than in the both methods group (70.0% versus 43.2%, p = 0.044). CONCLUSIONS: A molecular POC test could contribute to the accurate diagnosis of influenza in patients with influenza-like illness, especially those who visited a hospital immediately after the onset of symptoms.

Rapid detection and surveillance of cfiA-positive Bacteroides fragilis using matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

OBJECTIVES: To perform surveillance of cfiA-positive Bacteroides fragilis using new subtyping software module, MALDI Biotyper Subtyping Module (MBT Subtyping Module), on MALDI-TOF MS system, and to evaluate the detection ability of the module. METHODS: cfiA-positive strains were presumed using the module against B. fragilis isolated between 2006 and 2019. The cfiA gene was confirmed using PCR. In cfiA-positive B. fragilis, the insertion sequence (IS) elements were examined and the MBT STAR-BL assay was performed to examine meropenem hydrolysis activity. RESULTS: Of the 396 B. fragilis strains included, the MBT Subtyping Module detected 33 presumptive cfiA-positive strains (8.3%), of which 32 harbored the cfiA gene. The sensitivity and specificity of the MBT Subtyping Module for detecting cfiA-positive B. fragilis were 100.0% and 99.7%, respectively. Of the 32 strains harboring the cfiA gene, seven strains possessed IS elements, which were thought to induce high cfiA expression. Meropenem hydrolysis was detected in all seven strains that were positive for both cfiA and IS elements, and they exhibited resistance to meropenem and imipenem. The overall non-susceptibility rates to meropenem and imipenem were 84.8% and 36.4%, respectively, in the 33 presumptive cfiA-positive strains. CONCLUSION: The MBT Subtyping Module can detect cfiA-positive B. fragilis rapidly and accurately, supporting its use for surveillance of cfiA-positive B. fragilis in clinical settings.

Multicenter surveillance of the epidemiology of gram-negative bacteremia in Japan.

This study investigated the epidemiology of adult patients with bacteremia caused by seven major gram-negative bacteria during a year at four university hospitals in Japan. Of the 438 cases included, Escherichia coli (247 patients) was the most frequently isolated pathogen, followed by Klebsiella species (89 patients), Enterobacter species (31 patients), Pseudomonas aeruginosa (29 patients), Bacteroides species (19 patients), Acinetobacter species (12 patients) and Stenotrophomonas maltophilia (11 patients). The overall, crude in-hospital mortality was 16.4%, ranging from 9.7% with Enterobacter species to 54.5% with S. maltophilia. Community- and hospital-acquired bacteremia accounted for 52.5% and 47.5%, respectively. Enterobacteriaceae were isolated from 93.0% of patients with community-acquired bacteremia, whereas non-fermenting bacteria were isolated from 21.6% of patients with hospital-acquired bacteremia. Of the 423 patients analyzed, 86.8% and 13.2% were monomicrobial and polymicrobial infections, respectively, and their in-hospital mortalities were 13.9% and 30.4%, respectively. Although carbapenem-resistant Enterobacteriaceae were not detected, extended-spectrum ß-lactamase (ESBL) production was seen in 24.3% of E. coli and 6.7% of Klebsiella species, respectively. E. coli producing ESBL showed high resistance rates to fluoroquinolones (approximately 90%), in contrast to non-producing-E. coli (approximately 21%). The susceptibilities to carbapenems and fluoroquinolones were approximately 80% for P. aeruginosa, whereas all Acinetobacter species were susceptible to these antibiotics. Bacteroides species showed 100% susceptibility to piperacillin/tazobactam and carbapenems, but only 47.4% were susceptible to clindamycin. Further studies, as well as continued surveillance, are required to determine the appropriate therapeutic strategy for gram-negative bacteremia.

A novel macrolide, solithromycin suppresses mucin overexpression induced by Pseudomonas aeruginosa LPS in airway epithelial cells.

Some macrolides such as 14- and 15-membered macrolides have immunomodulatory effects such as suppression of mucin overproduction. Because a novel macrolide, solithromycin, was developed, we examined whether it suppresses the overexpression of mucin in vitro. A human airway epithelial cell line NCI-H292 was stimulated by Pseudomonas aeruginosa lipopolysaccharides to induce the overproduction of a major mucin, MUC5AC. Treatment with 10 µg/mL of solithromycin significantly inhibited LPS-induced MUC5AC in both mRNA and protein levels as well as a 15-membered macrolide, azithromycin. These findings support that solithromycin has a potential immunomodulatory effect.

Effect of probiotics on gut microbiome in patients with administration of surgical antibiotic prophylaxis: A randomized controlled study.

Surgical antibiotic prophylaxis (SAP) is recommended for the prevention of surgical site infections. However, there is a concern about adverse effects of SAP, such as antibiotic-associated diarrhea (AAD). To prevent AAD, administration of probiotics has been investigated. Although recent advances in next-generation sequencing makes it possible to analyze the gut microbiome, the effect of probiotics on the gut microbiome in the patients with SAP remains unknown. To test a hypothesis that SAP influences the gut microbiome and probiotics prevent the influence, a randomized controlled study was conducted with patients who underwent spinal surgery at Nagasaki University Hospital. After obtaining informed consent, the patients were automatically classified into the non-probiotics group and the probiotics group. In the probiotics group, the patients took 1 g of Enterococcus faecium 129 BIO 3B-R, 3 times a day on postoperative days (PODs) 1-5. The feces of all patients were sampled before administration of SAP and on PODs 5 and 10. We compared alpha and beta diversity and differential abundance analysis of the gut microbiome before and after SAP. During the study period, a total of 33 patients were evaluated, comprising 17 patients in the non-probiotics group and 16 in the probiotics group. There was no significant difference between the groups regarding patient characteristics. In alpha and beta diversity, there were no significant differences among all combinations. In differential abundance analysis at operational taxonomic unit level, Streptococcus gallolyticus and Roseburia were significantly increased in the non-probiotics group and significantly decreased in the probiotics group.

Molecular epidemiology of Clostridioides difficile and risk factors for the detection of toxin gene-positive strains.

In this study, we investigated all Clostridioides difficile strains isolated from stool samples in Nagasaki University Hospital between January 2012 and December 2014. Toxin genes (tcdA, tcdB and cdtA/cdtB) were analyzed for multiplex PCR in a total of 213 strains. In the toxin gene-positive strain, PCR ribotyping was conducted using capillary gel electrophoresis-based PCR and the Webribo database. Patients' backgrounds were analyzed by departments, disorders, antimicrobials, and clinical dates. The positive rates of tcdA, tcdB, and cdtA/cdtB genes were 62.9%, 63.4%, and 2.8%, respectively. The most frequent PCR ribotype was 047 (14.1%), followed by 014/0 (11.1%) and 002/0 (8.2%). In univariate analysis, the risk factors for the detection of toxin gene-positive strains in patients were older age (p = 0.0036), over ≥ 65 years old (p = 0.0175), the patients hospitalized at Department of Digestive Surgery (P = 0.0059), higher CRP level (P = 0.0395), and lower albumin level (p = 0.0014). In the multivariate analysis, the risk factor for detection of toxin gene-positive strains was the patients hospitalized at Department of Digestive Surgery (OR; 4.62, 95% CI; 1.18-18.0, p = 0.0274). In this study, the percentage of toxin gene-positive and cdtA/cdtB gene-positive strains was almost the same as that reported in previous studies, but the ribotype was different. In addition, we revealed that the risk factor associated with the detection of toxin gene-positive strains was the patients hospitalized at Department of digestive surgery.

Molecular and epidemiological analysis of IMP-1 metallo-ß-lactamase-producing Klebsiella pneumoniae in a tertiary care hospital in Japan.

This study investigated the molecular and phenotypic characteristics of carbapenemase-producing Klebsiella pneumoniae, and identified the risk factors underlying its acquisition. We evaluated K. pneumoniae isolated in Nagasaki University Hospital between January 2009 and June 2015. The presence of carbapenemase genes and plasmid characteristics were investigated. We performed multilocus sequence typing (MLST), and generated a dendrogram based on the results of pulsed-field gel electrophoresis (PFGE) for carbapenemase-producing strains. We also performed a case-control study of patients. Of the 88 K. pneumoniae strains that showed minimum inhibitory concentration ≥1 µg/mL for imipenem and/or meropenem, and that were available from our bacterial collection, 18 had the IMP-type carbapenemase gene, all of which were IMP-1 according to sequencing analysis. Strains included seven different sequence types (STs), of which the most common was ST1471. A dendrogram showed the significant similarity of some strains with relationships in PFGE patterns, STs, and the wards in which they were isolated. Plasmid incompatibility group was similar among the IMP-1 producers. Regarding risk factors, multivariate analysis showed that liver disease and previous uses of carbapenems and anti-fungal drugs were significant factors for the acquisition of IMP-1-producing strains. Our results demonstrate that IMP-1 is a major carbapenemase produced by K. pneumoniae. The PFGE results indicated the possibility of transmission in the hospital. The identified risk factors should be considered for appropriate antibiotic therapy and infection-control measures.

Efficacy and safety of cefditoren pivoxil for exacerbations of chronic obstructive pulmonary disease: A prospective multicenter interventional study.

Oral antibiotic therapy for patients with acute exacerbations of chronic obstructive pulmonary disease (COPD) usually involves an aminopenicillin with clavulanic acid, a macrolide, or a quinolone. To date, however, the clinical efficacy and safety of the oral cephalosporin cefditoren pivoxil has not been evaluated in Japanese patients with acute exacerbations of COPD. We conducted a prospective, multicenter, single arm, interventional study from January 2013 to March 2017 to determine the efficacy and safety of oral administration of 200 mg cefditoren pivoxil three times daily for 7 days in a cohort of 29 eligible patients from 15 hospitals. The mean age (SD) of participants was 73.1 (8.1) years and 28 had a smoking history (the mean [SD] of smoking index, 1426.7 [931.7]). The primary efficacy endpoint was clinical response (cure rate) at test of cure, which was set at 5-10 days after treatment ceased. Of the 23 patients finally analyzed, cure was achieved in 15 (65.2%), while 8 (34.8%) remained uncured. Previous experience of acute exacerbations significantly affected the cure rate: none of the three patients who had at least two prior exacerbations were cured, while 15 of the 20 patients with one or fewer prior exacerbations were cured (p = 0.032). The microbiological eradication rate was 88.9% at test of cure. During treatment, mild pneumonia was reported as an adverse event in one patient (3.4%) but resolved within 10 days of onset. We conclude that cefditoren pivoxil represents a viable alternative for antibiotic therapy in patients with few prior exacerbations.

In Vitro Activity of Lascufloxacin against Streptococcus pneumoniae with Mutations in the Quinolone Resistance-Determining Regions.

Lascufloxacin showed potent activity against Streptococcus pneumoniae with a GyrA or ParC mutation (first-step mutant). The frequency of selecting resistant strains tended to be lower for lascufloxacin than for levofloxacin and garenoxacin after drug exposure in first-step mutants but was similar in the comparison between lascufloxacin and moxifloxacin. The increase in MIC was smaller for lascufloxacin than for levofloxacin, garenoxacin, and moxifloxacin when clinical strains with only ParC mutations were exposed to the corresponding drug.

Susceptibility of Clostridium species isolated in Japan to fidaxomicin and its major metabolite OP-1118.

The narrow-spectrum macrocyclic antibiotic fidaxomicin is approved for treatment of Clostridium difficile infection in many countries and is currently under evaluation in Japan for this indication. This study was conducted to evaluate the effects of fidaxomicin and its major metabolite, OP-1118, on Clostridium spp. isolated in Nagasaki University Hospital, Japan. Isolates were cultured and antimicrobial susceptibility analyses performed according to the Clinical Laboratory Standards Institute methods. Ninety-eight isolates were obtained between 2012 and 2015, 50 of C. difficile and 48 of eight other Clostridium spp. Fidaxomicin had the lowest minimum inhibitory concentration (MIC) of the antimicrobials tested against C. difficile, with MIC90 (MIC range) 0.12 µg/mL (0.015-0.25), versus vancomycin MIC90 0.5 µg/mL (0.5), metronidazole MIC90 0.5 µg/mL (0.12-0.5), and OP-1118 MIC90 4.0 µg/mL (0.5-4.0). Fidaxomicin and OP-1118 each had a similar spectrum of activity against the other Clostridium spp. C. butyricum and the 29 fidaxomicin- and OP-1118-susceptible C. perfringens isolates had the lowest MIC values, and C. bolteae and C. hathewayi higher. All the C. ramosum isolates (n = 6) and one of 30 C. perfringens isolates had low susceptibility to fidaxomicin and OP-1118 (i.e., MIC >64 µg/mL). In summary, this study showed that fidaxomicin was active against a number of Clostridium spp., including C. difficile. Fidaxomicin was generally more effective than its major metabolite OP-1118, but both showed a similar spectrum of activity, suggesting that OP-1118 contributes to the antimicrobial activity of fidaxomicin. These findings were broadly in accordance with those of similar studies conducted in other settings.

Evaluation of FilmArray respiratory panel multiplex polymerase chain reaction assay for detection of pathogens in adult outpatients with acute respiratory tract infection.

Although viruses are the major pathogen that causes upper respiratory tract infection (URTI) and acute bronchitis, antibiotics have been prescribed. This was a prospective observational study in influenza epidemics that enrolled adult outpatients who visited a hospital with respiratory tract infection symptoms. In this study, we evaluated the usefulness of FilmArray respiratory panel (RP). Fifty patients were enrolled. FilmArray RP detected the pathogens in 28 patients. The common pathogens were influenza virus (n = 14), respiratory syncytial virus (n = 6), and human rhinovirus (n = 6). Of the 14 patients with influenza virus, 6 were negative for the antigen test. The physicians diagnosed and treated the patients without the result of FilmArray in this study. Of the patients with positive FilmArray RP, 9 were treated with antibiotics; however, bacteria were detected in only 3 patients. By implementing FilmArray RP, URTI and acute bronchitis would be precisely diagnosed, and inappropriate use of antibiotics can be reduced.

Efficacy and Pharmacokinetics of the Combination of OP0595 and Cefepime in a Mouse Model of Pneumonia Caused by Extended-Spectrum-Beta-Lactamase-Producing Klebsiella pneumoniae.

OP0595 (RG6080) is a novel diazabicyclooctane that inhibits class A and C serine beta-lactamases. Although the combination of OP0595 and cefepime (FEP) showed good in vitro activity against extended-spectrum-beta-lactamase (ESBL)-producing pathogens, the effect of the combination therapy against severe infections, such as pneumonia or bacteremia, remains unknown in vivo In this study, we investigated the efficacy and pharmacokinetics of the combination therapy of OP0595 and FEP in a mouse model of pneumonia caused by Klebsiella pneumoniae harboring SHV- and CTX-M-9-type ESBLs. The infected BALB/c mice were intraperitoneally administered saline (control), 100 mg/kg of body weight of FEP, 20 mg/kg of OP0595, or both FEP and OP0595, twice a day. The MIC of FEP against the bacteria was 8 mg/liter and markedly improved to 0.06 mg/liter with the addition of 0.5 mg/ml of OP0595. In the survival study, the combination of FEP and OP0595 significantly improved the survival rate compared with that reported with either OP0595 or FEP alone (P < 0.001). The number of bacteria in the lungs and blood significantly decreased in the combination therapy group compared to that reported for the monotherapy groups (P < 0.001). In addition, the in vivo effect depended on the dose of FEP. However, pharmacokinetic analysis revealed that the percentage of time above MIC remained constant when increasing the dose of FEP in combination with 20 mg/kg of OP0595. The results of our study demonstrated the in vivo effectiveness of the combination of OP0595 and FEP.

Efficacy and pharmacokinetics of ME1100, a novel optimized formulation of arbekacin for inhalation, compared with amikacin in a murine model of ventilator-associated pneumonia caused by Pseudomonas aeruginosa.

Background: Arbekacin is an aminoglycoside that shows strong antimicrobial activity against Gram-positive bacteria, including MRSA, as well as Pseudomonas aeruginosa . The therapeutic effectiveness of arbekacin is directly related to C max at the infection site. To maximize drug delivery to the respiratory tract and minimize the systemic toxicity, arbekacin optimized for inhalation, ME1100, is under development. In this study, we investigated the efficacy and pharmacokinetics of ME1100 in a murine model of ventilator-associated pneumonia caused by P. aeruginosa by using a customized investigational nebulizer system. Methods: The mice were treated for 5 min, once daily, with placebo, 3, 10 or 30 mg/mL ME1100 or 30 mg/mL amikacin. Results: In the survival study, the survival rate was significantly improved in the 10 and 30 mg/mL ME1100 treatment groups compared with that in the placebo group. The number of bacteria in the lungs was significantly lower in the 30 mg/mL ME1100 treatment group at 6 h after the initial treatment, compared with all other groups. In the pharmacokinetic study, the C max in the 30 mg/mL ME1100 treatment group in the epithelial lining fluid (ELF) and plasma was 31.1 and 1.2 mg/L, respectively. Furthermore, we compared the efficacy of ME1100 with that of amikacin. Although there were no significant differences in ELF and plasma concentrations between 30 mg/mL of ME1100 and 30 mg/mL of amikacin, ME1100 significantly improved the survival rate compared with amikacin. Conclusions: The results of our study demonstrated the in vivo effectiveness of ME1100 and its superiority to amikacin.

TNF-α inhibits the growth of Legionella pneumophila in airway epithelial cells by inducing apoptosis.

BACKGROUND: TNF-α plays an important role in the pathogenesis of Legionella pneumophila (Lp)-induced pneumonia. Patients undergoing anti-TNF-α therapy are at an increased risk of Lp infection. Lp infects both phagocytic and non-phagocytic cells such as airway epithelial cells; however, the role of TNF-α in airway epithelial cells is unknown. METHODS: Human airway epithelial cell line NCI-H292 was infected with Lp NUL1 strain. After infection, both intracellular growth of Lp and cell death were evaluated after treating the cells with or without TNF-α. Apoptosis was examined by performing activated caspase-3/7 staining and by using a pan-caspase inhibitor. RESULTS: Lp infected and replicated in NCI-H292 cells in a time-dependent manner, and TNF-α treatment of Lp-infected NCI-H292 cells inhibited Lp replication. Inhibitory effects of TNF-α on Lp replication were suppressed after treatment with a TNF-α-neutralizing antibody. Lp infection increased extracellular lactate dehydrogenase levels and decreased the number of living cells. Increased number of Lp-infected NCI-H292 cells showed caspase-3/7 activation, indicating they underwent apoptosis. TNF-α treatment inhibited Lp replication by increasing the apoptosis of NCI-H292 cells. CONCLUSIONS: Thus, our results suggested that airway epithelial cells were involved in the pathogenesis of Lp infection and that TNF-α played a protective role by inhibiting the intracellular replication of Lp and by increasing the apoptosis of Lp-infected airway epithelial cells. However, Lp infection should be investigated further in patients undergoing anti-TNF-α therapy who develop pneumonia.