Comparative efficacies of different antibiotic treatments to eradicate nontypeable Haemophilus influenzae infection

Haemophilus influenzae responds to glucocorticoids used in asthma therapy by modulation of biofilm formation and antibiotic resistance

Glucocorticosteroids are used as a main treatment to reduce airway inflammation in people with asthma who suffer from neutrophilic airway inflammation, a condition frequently associated with Haemophilus influenzae colonization. Here we show that glucocorticosteroids have a direct influence on the behavior of H. influenzae that may account for associated difficulties with therapy. Using a mouse model of infection, we show that corticosteroid treatment promotes H. influenzae persistence. Transcriptomic analysis of bacteria either isolated from infected mouse airway or grown in laboratory medium identified a number of genes encoding regulatory factors whose expression responded to the presence of glucocorticosteroids. Importantly, a number of these corticosteroid-responsive genes also showed elevated expression in H. influenzae within sputum from asthma patients undergoing steroid treatment. Addition of corticosteroid to H. influenzae led to alteration in biofilm formation and enhanced resistance to azithromycin, and promoted azithromycin resistance in an animal model of respiratory infection. Taken together, these data strongly suggest that H. influenzae can respond directly to corticosteroid treatment in the airway potentially influencing biofilm formation, persistence and the efficacy of antibiotic treatment.

Persistence of non-typeable Haemophilus Influenzae in the pharynx of children with adenotonsillar hypertrophy after treatment with azithromycin

This study was performed in children with adenotonsillar hypertrophy to evaluate the effect of azithromycin (AZT) on the presence of NTHi in monocyte/macrophages (CD14(+) cells) of adenoids/tonsils and the persistence of NTHi after adenotonsillectomy. A total of 36 pediatric patients participated in the study: 20 children were treated with AZT before adenotonsillectomy, and 16 children did not receive the antibiotic prior to surgery. NTHi were identified by culture and PCR in swabs and tissue samples. NTHi was detected in the lysates of CD14(+) cells by fluorescence in situ hybridization (FISH) and by culture. The molecular typing was used to cluster NTHi isolates from each child. The intracellular NTHi was found in 10 (62.5%) untreated patients and was identified in three (15%) azithromycin-treated patients (P = 0.003). The proportion of the persistent NTHi strains was similar in both groups. AZT treatment followed by adenotonsillectomy did not completely eliminate NTHi from pharynges; however, it significantly reduced the risk of carriage of Haemophilus influenzae inside the CD14(+) cells.

Haemophilus influenzae triggers autophagy in HEp-2 cells

The MAP-LC3 system regulates the intracellular formation of autophagy-associated vacuoles. These vacuoles contain the LC3 protein; thus it has been utilized as a marker to identify autophagosomes. The aim of our study was to investigate whether Haemophilus influenzae strains and their supernatants could activate autophagy in human larynx carcinoma cell line (HEp-2). We demonstrate that higher expression of the LC3B-II protein was induced, particularly by nontypeable Haemophilus influenzae (NTHi) 49766 and by supernatants, containing <50 kDa proteins, of both strains. Ultrastructural studies demonstrate vacuoles with a double membrane and/or membrane material inside, showing similar features to those of autophagic vacuoles. Together, our findings demonstrate that H. influenzae strains and their supernatants trigger an autophagic process.

Relationship between azithromycin susceptibility and administration efficacy for nontypeable Haemophilus influenzae respiratory infection

Nontypeable Haemophilus influenzae (NTHI) is an opportunistic pathogen that is an important cause of acute exacerbations of chronic obstructive pulmonary disease (AECOPD). COPD is an inflammatory disease of the airways, and exacerbations are acute inflammatory events superimposed on this background of chronic inflammation. Azithromycin (AZM) is a macrolide antibiotic with antibacterial and anti-inflammatory properties and a clinically proven potential for AECOPD prevention and management. Relationships between AZM efficacy and resistance by NTHI and between bactericidal and immunomodulatory effects on NTHI respiratory infection have not been addressed. In this study, we employed two pathogenic NTHI strains with different AZM susceptibilities (NTHI 375 [AZM susceptible] and NTHI 353 [AZM resistant]) to evaluate the prophylactic and therapeutic effects of AZM on the NTHI-host interplay. At the cellular level, AZM was bactericidal toward intracellular NTHI inside alveolar and bronchial epithelia and alveolar macrophages, and it enhanced NTHI phagocytosis by the latter cell type. These effects correlated with the strain MIC of AZM and the antibiotic dose. Additionally, the effect of AZM on NTHI infection was assessed in a mouse model of pulmonary infection. AZM showed both preventive and therapeutic efficacies by lowering NTHI 375 bacterial counts in lungs and bronchoalveolar lavage fluid (BALF) and by reducing histopathological inflammatory lesions in the upper and lower airways of mice. Conversely, AZM did not reduce bacterial loads in animals infected with NTHI 353, in which case a milder anti-inflammatory effect was also observed. Together, the results of this work link the bactericidal and anti-inflammatory effects of AZM and frame the efficacy of this antibiotic against NTHI respiratory infection.

Epidemiology, diagnosis, and antimicrobial treatment of acute bacterial meningitis

The epidemiology of bacterial meningitis has changed as a result of the widespread use of conjugate vaccines and preventive antimicrobial treatment of pregnant women. Given the significant morbidity and mortality associated with bacterial meningitis, accurate information is necessary regarding the important etiological agents and populations at risk to ascertain public health measures and ensure appropriate management. In this review, we describe the changing epidemiology of bacterial meningitis in the United States and throughout the world by reviewing the global changes in etiological agents followed by specific microorganism data on the impact of the development and widespread use of conjugate vaccines. We provide recommendations for empirical antimicrobial and adjunctive treatments for clinical subgroups and review available laboratory methods in making the etiological diagnosis of bacterial meningitis. Finally, we summarize risk factors, clinical features, and microbiological diagnostics for the specific bacteria causing this disease.

Experimental pulmonary infection and colonization of Haemophilus influenzae in emphysematous hamsters

BACKGROUND

Bacterial infection has been considered the main cause of acute exacerbations of chronic obstructive pulmonary disease (AECOPD). However, experimental model of COPD exacerbation induced by Haemophilus influenzae infection was not available up to now. Furthermore, only a few studies on evaluation of antibiotics using an H. influenzae infection model in mice have been reported. The aim of this work was to evaluate the activity of moxifloxacin on experimental pulmonary infection and colonization of H. influenzae in emphysematous hamsters.

METHODS

Pulmonary emphysema was developed by intratracheal instillation of porcine pancreatic elastase in golden hamsters, which were infected by agar-beads enclosing H. influenzae to establish animal models of AECOPD. Alterations of lung histopathology, inflammatory factor levels in plasma and bronchoalveolar lavage fluids (BALFs), viable cell counting of lung tissue were determined on different days after challenge and moxifloxacin administration.

RESULTS

Lung bacterial counts of BALFs and homogenates were significantly higher in emphysematous hamsters than those in normal non-emphysematous animals from 1 to 3 weeks after intratracheal inoculation of bacterial agar-beads suspensions. Moreover, H. influenzae colonized and survived for a longer period of time in emphysematous lungs than in normal non-emphysematous lungs after challenge. Efficacy of 3-day intragastric administration of moxifloxacin was proved by reduction in pulmonary H. influenzae burden and alleviation of inflammatory responses on days 4, 8 and 21 post-inoculation. No planktonic bacteria were isolated from BALFs in the first week after moxifloxacin treatment, and bacterial load in lung tissue homogenates declined significantly. Nevertheless, after 3 weeks, bacterial load in BALFs and homogenates of emphysematous lungs recovered to a large quantity. Inflammation in lung tissue, including lung consolidation, hemorrhage, and neutrophils infiltration, was conspicuously improved after administration of moxifloxacin. Levels of inflammatory factors in plasma were significantly decreased on days 8 and 21 after treatment compared with that without drug therapy. Inflammatory factors in BALF were also reduced, among which IL-8 dropped down markedly in early stage.

CONCLUSION

Our results suggest that chronic bacterial infection and colonization is highly correlated with lung emphysematous lesions, which would be one of the important mechanisms for repeated attacks of acute exacerbations of chronic pulmonary diseases and uncertain efficacies of antibiotics.

Clinical characteristics of respiratory syncytial virus infection-associated acute otitis media

BACKGROUND

It is known that children with respiratory syncytial virus (RSV) infection frequently have complications of acute otitis media (AOM).

METHODS

The hospital records of 148 inpatients aged 6-35 months who had RSV infection between January 2004 and December 2007, were retrospectively investigated.

RESULTS

Forty-six out of 148 children (31%) had AOM. There was a significantly greater number of children with fever who had AOM (P = 0.005). The percentage of children with beta-lactamase-non-producing ampicillin-resistant (BLNAR) Haemophilus influenzae in nasopharyngeal culture who had AOM showed a tendency to be greater than that of those who did not have AOM, but this was not statistically significant (P = 0.068). Moreover, BLNAR H. influenzae was positive in middle ear fluid specimens from four of five children with AOM who underwent tympanocentesis. There were no significant differences in the incidence of lower airway infection, leukocytes counts, or serum C-reactive protein levels between children with and without AOM.

CONCLUSIONS

Children who had RSV infection with AOM had a higher incidence of fever than those without AOM.