Development of potent antipseudomonal ß-lactams by means of polycarboxylation of aminopenicillins.

Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen that presents a serious risk to immunosuppressed individuals and other extremely vulnerable patients such as those in intensive care units. The emergence of multidrug-resistant Pseudomonas strains has increased the need for new antipseudomonal agents. In this study, a series of amino group-modified aminopenicillin derivatives was synthesized that have different numbers of carboxyl groups and structurally resemble carboxypenicillin-ureidopenicillin hybrids, and their antipseudomonal activities were evaluated. Among the derivatives synthesized, diethylenetriaminepentaacetic acid (DTPA)-modified amoxicillin (DTPA-Amox) showed potent antipseudomonal activity, not only against the laboratory strain PAO1 but also against clinically isolated Pseudomonas strains that were resistant to piperacillin and carbenicillin. DTPA-Amox had no obvious cytotoxic effects on cultured mammalian cells. In addition, in an in vivo model of leukopenia, DTPA-Amox treatment produced a moderate but statistically significant improvement in the survival of mice with P. aeruginosa strain PAO1 infection. These data suggest that polycarboxylation by DTPA conjugation is an effective approach to enhance antipseudomonal activity of aminopenicillins.

Airway Pseudomonas aeruginosa density in mechanically ventilated patients: clinical impact and relation to therapeutic efficacy of antibiotics.

BACKGROUND: The bacterial density of Pseudomonas aeruginosa is closely related to its pathogenicity. We evaluated the effect of airway P. aeruginosa density on the clinical course of mechanically ventilated patients and the therapeutic efficacy of antibiotics. METHODS: We retrospectively analyzed data of mechanically ventilated ICU patients with P. aeruginosa isolated from endotracheal aspirates. Patients were divided into three groups according to the peak P. aeruginosa density during ICU stay: low (≤ 104 cfu/mL), moderate (105‒106 cfu/mL), and high (≥ 107 cfu/mL) peak density groups. The relationship between peak P. aeruginosa density and weaning from mechanical ventilation, risk factors for isolation of high peak density of P. aeruginosa, and antibiotic efficacy were investigated using multivariate and propensity score-matched analyses. RESULTS: Four-hundred-and-sixty-one patients were enrolled. Patients with high peak density of P. aeruginosa had higher inflammation and developed more severe respiratory infections. High peak density of P. aeruginosa was independently associated with few ventilator-free days on day 28 (P < 0.01) and increased ICU mortality (P = 0.047). Risk factors for high peak density of P. aeruginosa were prolonged mechanical ventilation (odd ratio [OR] 3.07 95% confidence interval [CI] 1.35‒6.97), non-antipseudomonal cephalosporins (OR 2.17, 95% CI 1.35‒3.49), hyperglycemia (OR 2.01, 95% CI 1.26‒3.22) during ICU stay, and respiratory diseases (OR 1.9, 95% CI 1.12‒3.23). Isolation of commensal colonizer was associated with lower risks of high peak density of P. aeruginosa (OR 0.43, 95% CI 0.26‒0.73). Propensity score-matched analysis revealed that antibiotic therapy for patients with ventilator-associated tracheobronchitis improved weaning from mechanical ventilation only in the high peak P. aeruginosa group. CONCLUSIONS: Patients with high peak density of P. aeruginosa had worse ventilator outcome and ICU mortality. In patients with ventilator-associated tracheobronchitis, antibiotic therapy was associated with favorable ventilator weaning only in the high peak P. aeruginosa density group, and bacterial density could be a good therapeutic indicator for ventilator-associated tracheobronchitis due to P. aeruginosa.

Lung abscess following bronchoscopy due to multidrug-resistant Capnocytophaga sputigena adjacent to lung cancer with high PD-L1 expression.

Lung abscess following flexible bronchoscopy is a rare and sometimes fatal iatrogenic complication. Here, we report the first case of a lung abscess caused by multidrug-resistant Capnocytophaga sputigena following bronchoscopy. A 67-year-old man underwent bronchoscopy to evaluate a lung mass. Seven days after transbronchial lung biopsy, he presented with an abscess formation in a lung mass. Empirical antibiotic therapy, including with garenoxacin, ampicillin/sulbactam, clindamycin and cefepime, was ineffective. Percutaneous needle aspiration of lung abscess yielded C. sputigena resistant to multiple antibiotics but remained susceptible to carbapenem. He was successfully treated by the combination therapy with surgery and with approximately 6 weeks of intravenous carbapenem. Finally he was diagnosed with a lung abscess with adenocarcinoma expressing high levels of programmed cell death ligand 1. The emergence of multidrug-resistant Capnocytophaga species is a serious concern for effective antimicrobial therapy. Clinicians should consider multidrug-resistant C. sputigena as a causative pathogen of lung abscess when it is refractory to antimicrobial treatment.

Protective effect of Galectin-9 in murine model of lung emphysema: Involvement of neutrophil migration and MMP-9 production.

PURPOSE: Chronic obstructive pulmonary disease (COPD) is characterized by irreversible airflow obstruction and pulmonary emphysema. Persistent inflammation and remodeling of the lungs and airways result in reduced lung function and a lower quality of life. Galectin (Gal)-9 plays a crucial role as an immune modulator in various diseases. However, its role in the pathogenesis of pulmonary emphysema is unknown. This study investigates whether Gal-9 is involved in pulmonary inflammation and changes in emphysema in a porcine pancreatic elastase (PPE)-induced emphysema model. MATERIALS AND METHODS: Gal-9 was administered to mice subcutaneously once daily from 1 day before PPE instillation to day 5. During the development of emphysema, lung tissue and bronchoalveolar lavage fluid (BALF) were collected. Histological and cytological findings, concentrations of chemokines and matrix metalloproteinases (MMPs) in the BALF, and the influence of Gal-9 treatment on neutrophils were analyzed. RESULTS: Gal-9 suppressed the pathological changes of PPE-induced emphysema. The mean linear intercept (Lm) of Gal-9-treated emphysema mice was significantly lower than that of PBS-treated emphysema mice (66.1 ± 3.3 µm vs. 118.8 ± 14.8 µm, respectively; p < 0.01). Gal-9 decreased the number of neutrophils and levels of MMP-9, MMP-2 and tissue inhibitor of metalloproteinases (TIMP)-1 in the BALF. The number of neutrophils in the BALF correlated significantly with MMPs levels. Interestingly, Gal-9 pretreatment in vitro inhibited the chemotactic activity of neutrophils and MMP-9 production from neutrophils. Furthermore, in Gal-9-deficient mice, PPE-induced emphysema progressed significantly compared with that in wild-type (WT) mice (108.7 ± 6.58 µm vs. 77.19 ± 6.97 µm, respectively; p < 0.01). CONCLUSIONS: These results suggest that Gal-9 protects PPE-induced inflammation and emphysema by inhibiting the infiltration of neutrophils and decreasing MMPs levels. Exogenous Gal-9 could be a potential therapeutic agent for COPD.

Efficacy of direct hemoperfusion using polymyxin B-immobilized fiber column (PMX-DHP) in rapidly progressive interstitial pneumonias: results of a historical control study and a review of previous studies.

BACKGROUND: Direct hemoperfusion using polymyxin B-immobilized fiber column (PMX-DHP) therapy has been approved for sepsis-associated acute respiratory distress syndrome, but its efficacy for other rapidly progressive interstitial pneumonias (RPIPs) is unclear. The purpose of this study was to examine the efficacy of PMX-DHP therapy for acute respiratory failure in patients with RPIPs, when compared with a historical control receiving conventional treatment without PMX-DHP. METHODS: This study comprised 77 patients with RPIPs in our institute between January 2002 and December 2015. The initial 36 patients between January 2002 and March 2007 were treated without PMX-DHP (historical control group), and the following 41 patients between April 2007 and December 2015 were treated with PMX-DHP (PMX-DHP group) once daily for two successive days concurrently with corticosteroids and/or immunosuppressive agents. The 90-day mortality and clinical factors were compared between the groups. Cox proportional hazards models were constructed to analyze 90-day mortality and identify predictors. RESULTS: The 90-day mortality rate was significantly lower in the PMX-DHP group than in the controls (41.5% versus 66.7%, p = 0.019). PMX-DHP therapy was significantly associated with mortality (hazard ratio 0.505; 95% confidence interval, 0.270-0.904; p = 0.032). There were significant differences in the serial changes in the PaO2/FiO2 ratio, SOFA score, and blood neutrophil counts from days 0-5 after PMX-DHP between the survivor and non-survivor groups ( p = 0.015, p < 0.001, p = 0.035, respectively). The improved PaO2/FiO2 ratio on day 3 significantly correlated with the change in blood neutrophil counts (rs = -0.431, p = 0.006). CONCLUSIONS: PMX-DHP therapy may be effective in RPIPs patients accompanied by acute respiratory failure and is expected to reduce mortality rates.

Aerosolized tobramycin for Pseudomonas aeruginosa ventilator-associated pneumonia in patients with acute respiratory distress syndrome.

BACKGROUND: Ventilator-associated pneumonia (VAP) due to Pseudomonas aeruginosa has a high mortality and recurrence rate, especially in patients with acute respiratory distress syndrome (ARDS). Therefore, new therapeutic strategies against severe pneumonia are needed. This study evaluated the efficacy of aerosolized tobramycin for P. aeruginosa VAP in ARDS patients. METHODS: A retrospective analysis was performed on patients who developed VAP caused by P. aeruginosa during the course of ARDS at the intensive care unit (ICU) of Kumamoto University Hospital. Aerosolized tobramycin inhalation solution (TIS) 240 mg was administered daily for 14 days in addition to systemic antibiotics. RESULTS: A total of 44 patients (TIS group, n = 22; control group, n = 22) were included in the analysis. No significant differences were found between the two groups in terms of clinical characteristics, including acute physiology and chronic health evaluation II score upon ICU admission. The TIS group had significantly lower recurrence of P. aeruginosa VAP (22.7% vs. 52.4%, P = 0.04) and ICU mortality (22.7% vs. 63.6%, P < 0.01) than the control group. Bacterial concentration in tracheal aspirate (mean log 10 cfu/mL ± SD on days 2-5: 1.2 ± 1.3 vs. 5.0 ± 2.3, P < 0.01) decreased more rapidly and markedly in the TIS group compared with the control group. CONCLUSION: Aerosolized tobramycin was an effective therapeutic strategy for P. aeruginosa VAP patients with ARDS.

Quantitative detection of periodontopathic bacteria in lower respiratory tract specimens by real-time PCR.

The presence of common periodontopathic bacteria, the Fusobacterium nucleatum-periodonticum-simiae group, Prevotella intermedia, and Porphyromonas gingivalis was determined from respiratory tract specimens of bacterial pneumonia by real-time PCR using universal and species-specific TaqMan probe/primer sets. 42 patients with infectious pneumonia and 45 patients without infectious pneumonia were retrospectively enrolled in clinical studies. Periodontopathic bacterial DNA was found in 57.1% cases of infectious pneumonia and 31.1% cases of noninfectious pulmonary disease. However, the proportion of periodontopathic bacterial DNA did not differ between the two groups, and the presence or proportion of periodontopathic bacterial DNA was not related to any clinical index of pneumonia. Only two pneumonia cases consisted of >30% Fusobacterium DNA, suggesting that Fusobacterium was the causal pathogen in these cases. Our findings suggest that the periodontopathic bacteria rarely proliferate and be etiological pathogen in lower airway tract. However, further study is necessary, focusing on the pathogenicity of F. nucleatum in pulmonary infectious disease.

Pseudomonas aeruginosa Bacteremia among Immunocompetent and Immunocompromised Patients: Relation to Initial Antibiotic Therapy and Survival.

Pseudomonas aeruginosa bacteremia occurs mainly in immunocompromised patients. However, P. aeruginosa bacteremia in immunocompetent patients has also been reported. The aim of this study was to evaluate the clinical characteristics of P. aeruginosa bacteremia in relation to the immune status of the patients. The medical records of 126 adult patients with P. aeruginosa bacteremia in Nagasaki University Hospital were retrospectively reviewed between January 2003 and December 2012. Of 126 patients with P. aeruginosa bacteremia, 60 patients (47.6%) were classified as immunocompetent. Mortality in immunocompetent patients tended to be lower than in immunocompromised patients (7-day mortality, 8% vs. 30%, P < 0.01; 30-day mortality, 23% vs. 39%, P = 0.053). Multivariate analysis showed that a higher sequential organ failure assessment score (hazard ratio [HR]: 1.27, P < 0.01) and underlying malignancies (HR: 3.33, P < 0.01) were independently associated with 30-day mortality. Initial antibiotic therapy (HR: 0.21, P < 0.01) and patients' immune status (HR: 0.29, P = 0.02) also had a significant impact on survival. However, there was a significant interaction between these 2 variables (P = 0.03 for interaction). A subgroup analysis showed that in immunocompromised, but not immunocompetent patients, initial appropriate antibiotic therapy was associated with lower mortality (30-day mortality 20.5% vs. 66.7%, P < 0.01 by log-rank test).

Active Surveillance of Methicillin-Resistant Staphylococcus aureus Using a Fully Automated Molecular Test in an Emergency Medical Center.

The prevention and control of methicillin-resistant Staphylococcus aureus (MRSA) are important, particularly in emergency units. The active surveillance of MRSA was prospectively performed at the emergency medical center of Nagasaki University Hospital. After obtaining nasal swab specimens, a fully automated molecular test (FAMT) and a culture-screening method were utilized for MRSA detection. A total of 150 patients were enrolled in the study, and 366 nasal swab specimens were obtained. MRSA was detected by culture in 11 (7.3%) patients including one new acquisition and by the FAMT in 34 (22.7%) patients including 13 new acquisitions. The sensitivity, specificity, positive predictive value, and negative predictive value of the FAMT at the patient level were 86.7, 85.2, 39.4, and 98.3%, respectively, when compared with the culture-based results. An FAMT can effectively detect MRSA colonization, which may remain undetected with the conventional method, and it may be useful in detecting newly acquired MRSAs.

Immunomodulatory effect of linezolid on methicillin-resistant Staphylococcus aureus supernatant-induced MUC5AC overexpression in human airway epithelial cells.

Linezolid is the first member of the oxazolidinones and is active against drug-resistant Gram-positive pathogens, such as methicillin-resistant Staphylococcus aureus (MRSA). Additionally, linezolid shows an immunomodulatory effect, such as inhibition of inflammatory cytokine production. In this study, we examined the effect of linezolid on MRSA-induced MUC5AC overexpression in airway epithelial cells. In this study, an MRSA supernatant was used to avoid the direct effect of linezolid on MRSA. MUC5AC protein production was significantly increased with a 40-fold dilution of MRSA supernatant. At the mRNA level, MUC5AC gene expression was significantly increased 6 and 9 h after stimulation. In an inhibition study, linezolid significantly reduced MRSA-induced MUC5AC protein and mRNA overexpression at concentrations of 5 and 20 µg/ml, which were the same as the trough and peak concentrations in human epithelial lining fluid. In an analysis of cell signaling, among the mitogen-activated protein kinase inhibitors, only the extracellular signal-regulated protein kinase 1/2 (ERK1/2) inhibitor reduced the MUC5AC protein production to the same level as that of the control; on Western blot analysis, only ERK1/2 was phosphorylated by the MRSA supernatant. In addition, the ERK1/2 phosphorylation was inhibited by linezolid. MUC5AC and MUC5B are the major barrier that traps inhaled microbial organisms, particulates, and foreign irritants. However, in patients with chronic respiratory diseases, pathogen-induced MUC5AC overexpression causes many problems, and control of the overexpression is important. Thus, this study revealed that linezolid showed a direct immunomodulatory effect in airway epithelial cells.

Predictors of the pathogenicity of methicillin-resistant Staphylococcus aureus nosocomial pneumonia.

BACKGROUND AND OBJECTIVE: The clinical characteristics of patients with nosocomial pneumonia (NP) associated with methicillin-resistant Staphylococcus aureus (MRSA) infection are not well characterized. METHODS: Three hundred and thirty-seven consecutive patients with MRSA isolation from respiratory specimens who attended our hospital between April 2007 and March 2011 were enrolled. Patients characteristics diagnosed with 'true' MRSA-NP were described with regards to clinical, microbiological features, radiological features and genetic characteristics of the isolates. The diagnosis of 'true' MRSA-NP was confirmed by anti-MRSA treatment effects, Gram-staining or bronchoalveolar lavage fluid culture. RESULTS: Thirty-six patients were diagnosed with 'true' MRSA-NP, whereas 34 were diagnosed with NP with MRSA colonization. Patients with a MRSA-NP had a Pneumonia Patient Outcomes Research Team score of 5 (58.3% vs 23.5%), single cultivation of MRSA (83.3% vs 38.2%), MRSA quantitative cultivation yielding more than 10(6) CFU/mL (80.6% vs 47.1%), radiological findings other than lobar pneumonia (66.7% vs 26.5%), and a history of head, neck, oesophageal or stomach surgery (30.6% vs 11.8%). These factors were shown to be independent predictors of the pathogenicity of 'true' MRSA-NP by multivariate analysis (P < 0.05). CONCLUSIONS: 'True' MRSA-NP shows distinct clinical and radiological features from NP with MRSA colonization.

Influence of antimicrobial regimen on decreased in-hospital mortality of patients with MRSA bacteremia.

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most important causes of bacteremia. Recently, several epidemiological and microbiological changes have become evident in MRSA infections. The purposes of this study were to assess clinical characteristics of patients with MRSA bacteremia and microbiological changes in MRSA. We conducted a retrospective observational study on patients with MRSA bacteremia who were hospitalized between 2008 and 2011. We used univariate and multivariate analysis to evaluate the predictors associated with 30-day mortality. The 7-day and 30-day mortality rates were 12.0% and 25.3%, respectively. According to multivariate analysis, the independent predictors that associated with 30-day mortality were leukopenia, low serum albumin, high sequential organ failure assessment (SOFA) score, and quinolone use within 30 days. Compared to previous data (2003-2007), the SOFA score of the new data set remained unchanged, but in-hospital mortality decreased significantly. In particular, the mortality associated with use of vancomycin (VCM) was significantly lower. Although the minimum inhibitory concentration of VCM required to inhibit the growth of 90% of organisms (MIC90) had not changed, the trough value of VCM changed significantly; a VCM trough value of 10 or greater was significantly higher compared to previous data. Of the staphylococcal cassette chromosome mec (SCCmec) types, SCCmec II values decreased significantly, and SCCmec I and IV values increased significantly. Our results indicate that changes in VCM usage might contribute to decreased in-hospital mortality.

Establishment of a new murine model of liver abscess induced by Fusobacterium necrophorum injected into the caudal vein.

Anaerobic bacterial infection is often accompanied by abscess formation; however, few in vivo studies have been published with descriptive data specifically evaluating antimicrobial activity in the presence of abscesses. The aim of this study was to establish a murine model of anaerobic infection with abscess formation and to verify the utility of this model for evaluating the in vivo efficacy of an antimicrobial agent. A clinical isolate of Fusobacterium necrophorum was inoculated into the caudal vein of immunocompetent BALB/c mice at 10(8) c.f.u. per mouse. Changes in body weight, bacterial load and histopathology of key organs were evaluated. After inoculation, bacterial counts in the liver increased from 10(4) to 10(8) c.f.u. after 1-3 days, and liver abscess formation was observed on the day following infection. Abscess formation and bacterial growth were not observed in other organs. In this model, 3 days of treatment with 5 mg metronidazole kg(-1) eradicated F. necrophorum in the liver; however, a reduction in bacterial load was not observed with 0.05 mg metronidazole kg(-1). In this study, we established a novel murine model of F. necrophorum liver abscess via haematogenous infection that may be useful for investigating in vivo antimicrobial activity against anaerobic abscesses and understanding the pathogenesis of F. necrophorum infection.

In vivo efficacy of biapenem with ME1071, a novel metallo-ß-lactamase (MBL) inhibitor, in a murine model mimicking ventilator-associated pneumonia caused by MBL-producing Pseudomonas aeruginosa.

ME1071, a maleic acid derivative, is a novel, specific inhibitor of metallo-ß-lactamases (MBLs). In vitro, ME1071 can potentiate the activity of carbapenems against MBL-producing Pseudomonas aeruginosa. To confirm the clinical efficacy of ME1071 in ventilator-associated pneumonia (VAP) caused by MBL-producing P. aeruginosa, a mouse model that mimics VAP by placement of a plastic tube in the bronchus was used. Biapenem (100 mg/kg) or ME1071 plus biapenem (each 100 mg/kg) was administered intraperitoneally every 12 h beginning at 12 h after inoculation. Survival was evaluated over 7 days. At 30 h post infection, mice were sacrificed and the numbers of viable bacteria in the lungs and bronchoalveolar lavage fluid (BALF) were compared. Histopathological analysis of lung specimens was also performed. The pharmacokinetics of ME1071 was analysed after initial treatment. The ME1071 plus biapenem combination group displayed significantly longer survival compared with the control and biapenem monotherapy groups (P<0.05). Furthermore, the number of viable bacteria in the lungs was significantly lower in the combination group (P<0.05). Histopathological examination of lung specimens indicated that progression of lung inflammation was prevented in the combination group. Furthermore, total cell and neutrophil counts, as well as cytokine levels, in BALF were significantly decreased (P<0.05) in the combination group. The percentage time above the MIC (%T>MIC) for biapenem without ME1071 was 0% in plasma; however, this value was elevated to 10.8% with ME1071. These results suggest that ME1071 is potent and effective for treatment of VAP caused by MBL-producing P. aeruginosa.

Azithromycin attenuates lung inflammation in a mouse model of ventilator-associated pneumonia by multidrug-resistant Acinetobacter baumannii.

Acinetobacter baumannii is one of the main pathogens that cause ventilator-associated pneumonia (VAP) and is associated with a high rate of mortality. Little is known about the efficacy of macrolides against A. baumannii. In order to confirm the efficacy of azithromycin (AZM) against VAP caused by multidrug-resistant A. baumannii (MDRAB), we used a mouse model that mimics VAP by placement of a plastic tube in the bronchus. AZM (10 and 100 mg/kg of body weight) was administered subcutaneously every 24 h beginning at 3 h after inoculation. Phosphate-buffered saline was administered as the control. Survival was evaluated over 7 days. At 48 h postinfection, mice were sacrificed and the numbers of viable bacteria in lungs and bronchoalveolar lavage fluid were compared. Histopathological analysis of lung specimens was also performed. The treatment groups displayed significantly longer survival than the control group (P < 0.05). AZM did not have an antimicrobial effect. Histopathological examination of lung specimens indicated that the progression of lung inflammation was prevented in the AZM-treated groups. Furthermore, total cell and neutrophil counts, as well as cytokine levels, in bronchoalveolar lavage fluid were significantly decreased (P < 0.05) in the AZM-treated groups. AZM may have a role for the treatment of VAP with MDRAB because of its anti-inflammatory effects.

Efficacy of AiiM, an N-acylhomoserine lactonase, against Pseudomonas aeruginosa in a mouse model of acute pneumonia.

Quorum sensing (QS) in Pseudomonas aeruginosa regulates the production of many virulence factors and plays an important role in the pathogenesis of P. aeruginosa infection. N-acyl homoserine lactones (AHL) are major QS signal molecules. Recently, a novel AHL-lactonase enzyme, AiiM, has been identified. The aim of this study was to evaluate the effect of AiiM on the virulence of P. aeruginosa in a mouse model of acute pneumonia. We developed a P. aeruginosa PAO1 strain harboring an AiiM-expressing plasmid. The production of several virulence factors by the AiiM-expressing strain was examined. Mice were intratracheally infected with an AiiM-expressing PAO1 strain. Lung histopathology, bacterial burden, and bronchoalveolar lavage (BAL) fluid were assessed at 24 h postinfection. AiiM expression in PAO1 reduced production of AHL-mediated virulence factors and attenuated cytotoxicity against human lung epithelial cells. In a mouse model of acute pneumonia, AiiM expression reduced lung injury and greatly improved the survival rates. The levels of proinflammatory cytokines and myeloperoxidase activity in BAL fluid were significantly lower in mice infected with AiiM-expressing PAO1. Thus, AiiM can strongly attenuate P. aeruginosa virulence in a mammalian model and is a potential candidate for use as a therapeutic agent against P. aeruginosa infection.

In vivo efficacy of daptomycin against methicillin-resistant Staphylococcus aureus in a mouse model of hematogenous pulmonary infection.

Daptomycin is inactivated by pulmonary surfactant, but its effectiveness in hematogenous pulmonary infection has been poorly studied. The potential therapeutic application was evaluated in a methicillin-resistant Staphylococcus aureus (MRSA) hematogenous pulmonary infection mouse model. Compared with control results, daptomycin improved survival (P < 0.001) and decreased the number of abscesses and bacteria in the lungs (P < 0.01). Daptomycin may be an effective therapeutic option for MRSA hematogenous pulmonary infection.

Macrolides inhibit Fusobacterium nucleatum-induced MUC5AC production in human airway epithelial cells.

Fusobacterium nucleatum is one of the most common anaerobic bacteria in periodontitis and is responsible for several extraoral infections, including respiratory tract diseases. In this study, we examined whether F. nucleatum induces mucin secretion in airway epithelial cells. We also examined the effects of macrolides on F. nucleatum-induced mucus production compared with the effects of other antibiotics that exert anti-anaerobic activities. The production of MUC5AC, the major core protein of mucin secreted from the airway surface epithelium, in bronchial epithelial cells after stimulation with culture supernatants (Sup) of F. nucleatum was analyzed by performing enzyme-linked immunosorbent assay and quantitative RT-PCR. The cell-signaling pathway of F. nucleatum Sup stimulation was also analyzed by Western blotting. For inhibition studies, cells were treated with azithromycin, clarithromycin, clindamycin (CLDM), and metronidazole (MTZ). The F. nucleatum Sup induced NCI-H292 cells to express MUC5AC at both the protein level and the mRNA level in both a time- and dose-dependent manner. Macrolides inhibited F. nucleatum Sup-induced MUC5AC production, while CLDM and MTZ were less effective. F. nucleatum Sup induced the phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2), and this induction was suppressed by macrolides. F. nucleatum Sup-induced MUC5AC production was blocked by the ERK pathway inhibitor U0126. F. nucleatum is likely to contribute to excessive mucin production, which suggests that periodontitis may correlate with the pathogenesis of chronic respiratory tract infection. Macrolides seem to reduce this mucin production and might represent an additional means of therapeutic intervention for F. nucleatum respiratory tract infections other than CLDM and MTZ.

Molecular characterization of quinolone-insensitive Streptococcus pneumoniae isolates from Japanese patients.

Fluoroquinolone resistance in Streptococcus pneumoniae has become a growing concern. Using S. pneumoniae isolates (n = 61) for which the minimum inhibitory concentration (MIC) of levofloxacin was not less than 1 µg/ml, we investigated the susceptibility of S. pneumoniae isolates to other fluoroquinolones (ciprofloxacin, pazufloxacin, moxifloxacin, garenoxacin, and sitafloxacin) and sequenced the quinolone resistance-determining regions of two topoisomerase genes, parC and gyrA, in these isolates to identify mutations. As the number of missense mutations increased, the MIC values for each drug increased. However, moxifloxacin, garenoxacin, and sitafloxacin showed potent activities against the isolates, while the MICs of ciprofloxacin and pazufloxacin were higher than the MICs of levofloxacin.

Live Legionella pneumophila induces MUC5AC production by airway epithelial cells independently of intracellular invasion.

The airway epithelium is the initial barrier against airborne pathogens, and it plays many roles in host airway defense. Legionella pneumophila is an intracellular pathogen that causes rapidly advancing pneumonia and is sometimes life-threatening. Here, we evaluated the role of the airway epithelial cells in the defense against L. pneumophila by examining mucus production in vitro. The production of MUC5AC, a major mucin protein, was not induced by formalin- or ultraviolet-killed L. pneumophila, but it was induced by live L. pneumophila. Similarly, nuclear factor-kappaB (NF-κB) was activated only by live L. pneumophila. Inhibitors of ERK and JNK, but not p38, dose-dependently inhibited the induction of MUC5AC by live L. pneumophila. Inhibition of intracellular invasion by cytochalasin D did not affect MUC5AC production. Taken together, the results suggest that live L. pneumophila induces MUC5AC production via the ERK-JNK and NF-κB pathways without internalization of bacteria and that the airway epithelium produces mucin as part of the immune response against L. pneumophila.