Effect of dirithromycin on Haemophilus influenzae infection of the respiratory mucosa

Intelligent medical diagnostics via molecular logic

In this communication, we describe the integration of microarray sensor technology with logic capability for screening combinations of proteins and DNA in a biological sample. In this system, we have demonstrated the use of a single platform amenable to both protein detection and protein-DNA detection using molecular logic gates. The pattern of protein and DNA inputs results in fluorescence outputs according to a truth table for AND and INHIBIT gates, thereby demonstrating the feasibility of performing medical diagnostics using a logic gate design. One possible application of this technique would be direct screening of various medical conditions that are dependent on combinations of diagnostic markers.

Microsphere-based rolling circle amplification microarray for the detection of DNA and proteins in a single assay

We describe a high-density microarray for simultaneous detection of proteins and DNA in a single test. In this system, Rolling Circle Amplification (RCA) was used as a signal amplification method for both protein and nucleic acid detection. The microsphere sensors were tested with synthetic DNA and purified recombinant protein analytes. The target DNA sequence was designed from a highly conserved gene that encodes the outer membrane protein P6 (OMP-P6) of both typeable and nontypeable strains of Haemophilus influenzae. The proinflammatory mediators IL-6 and IL-8 were selected as target proteins. Capture antibodies were first immobilized on fluorescently encoded microspheres. The microspheres were then loaded into the etched microwells of an imaging optical fiber bundle. A sandwich assay was performed for target proteins IL-6 and IL-8 using biotin-labeled secondary antibodies. Biotinylated capture DNA probes were then attached to the detection antibodies via an avidin bridge. A padlock probe, complementary to the target sequence, was subsequently hybridized to the capture probe. In the presence of the target sequence, the padlock probe was ligated, and this circular sequence was used for RCA. Following RCA, multiple fluorescently labeled signal probes were hybridized to each amplified sequence, and the microarray was imaged using an epi-fluorescence microscope. With this assay, detection limits down to 10 fM and 1 pM were achieved for proteins and target DNA, respectively. In addition to this new approach for detecting both protein and DNA in a single test using RCA, the limit of detection for IL-8 and IL-6 was improved by 3 orders of magnitude compared to similar microsphere-based assays.

Beneficial effect of antibiotics on ciliary beat frequency of human nasal epithelial cells exposed to bacterial toxins

In the present study, we explored whether the cilio-inhibitory effect induced by toxins derived from bacterial infections could be compensated for by a cilio-stimulatory effect of antibiotics. Human nasal epithelial cells (HNEC) expressing beating cilia were grown as monolayers. Ciliary beat frequency (CBF) was determined using an inverted microscope coupled with a high-speed digital camera. Clarithromycin and neomycin did not influence ciliary activity. Bacitracin, clindamycin, gramicidin and roxithromycin increased CBF significantly: by 50 +/- 12%, 54 +/- 16%, 31 +/- 16% and 31 +/- 18%, respectively. A 30 min exposure to Staphylococcus aureus enterotoxin B (SEB) and Pseudomonas aeruginosa lipopolysaccharide (PAL) decreased CBF significantly, by 37 +/- 16 and 28 +/- 12%, respectively. In contrast with exposure to the toxin alone, co-incubation of the nasal monolayer cells with PAL and bacitracin or clindamycin did not result in a decrease in CBF after 30 and 60 min. The effect of SEB could be compensated for by bacitracin but not by clindamycin. After a 12 h preincubation period with SEB, co-incubation with either bacitracin or clindamycin resulted in the complete recovery of CBF. This study suggests that topical antibiotic treatment of nasal infections could result in a dual positive effect, namely treatment of the bacterial infection and recovery of ciliary activity.

Differential infection efficiencies of peripheral lung and tracheal tissues in sheep infected with Visna/maedi virus via the respiratory tract

The main routes of transmission of Visna/maedi virus (VMV), an ovine lentivirus, are thought to be through ingestion of infected colostrum and/or milk or through inhalation of respiratory secretions. Whereas oral transmission appears to be mediated via epithelial cells within the small intestine, the mechanism of virus uptake in the respiratory tract is unknown. In addition, it is not known whether infection is mediated by cell-associated or cell-free VMV, previous studies having not addressed this question. Intratracheal (i.t.) injection of VMV is known to be a highly efficient method of experimental infection, requiring as little as 101 TCID50 VMV for successful infection. However, using a tracheal organ culture system, we show here that ovine tracheal mucosa is relatively resistant to VMV, with detectable infection only seen after incubation with high titres of virus (⩾105 TCID50 ml−1). We also demonstrate that i.t. injection results in exposure of both trachea and the lower lung and that the time taken for viraemia and seroconversion to occur after lower lung instillation of VMV was significantly shorter than that observed for tracheal instillation of an identical titre of virus (P=0.030). This indicates that lower lung and not the trachea is a highly efficient site for VMV entry in vivo. Furthermore, cell-free virus was identified within the lung-lining fluid of naturally infected sheep for the first time. Together, these results suggest that respiratory transmission of VMV is mediated by inhalation of aerosols containing free VMV, with subsequent virus uptake in the lower lung.

Five-day moxifloxacin therapy compared with 7-day co-amoxiclav therapy for the treatment of acute exacerbation of chronic bronchitis

In this randomized, non-blinded study, the efficacy and safety of a 5-day course of moxifloxacin (one 400 mg tablet daily) was compared with that of co-amoxiclav (one 625 mg tablet every 8h) for 7 days, for the treatment of acute exacerbations of chronic bronchitis (AECB). A total of 162 patients with clear signs of an acute exacerbation of chronic bronchitis were enrolled. Of these, 153 could be studied. Seventy-nine patients were randomized in the moxifloxacin arm and 74 in the co-amoxiclav arm of the study. The primary efficacy parameter was clinical response at 14 days in the evaluable population. A clinical success was classified as resolution or improvement of symptoms. Variables used to assess clinical response included wheeze, cough, dyspnoea, sputum volume, rales and ronchi. The success rate in the moxifloxacin group was 88.6% (70 of 79) and that for co-amoxiclav group was 89.2% (66 of 74). At follow-up (28-35 days post-treatment), the continued clinical cure rates were 90.0% (63 of 70) for moxifloxacin and 89.4% (59 of 66) for co-amoxiclav. No significant differences were detected between the two groups. A total of 78 pathogenic bacteria were isolated from the sputum samples of the patients, with Moraxella catarrhalis, Haemophilus influenzae and Streptococcus pneumoniae being the most frequently isolated pathogens. The eradication rate at 14 days in the valid patients was similar for both groups, 90.9% (20 of 22) for the moxifloxacin group and 90.0% (18 of 20) for the co-amoxiclav group. Both drugs were well tolerated with no differences in the drug-related adverse effects or the patients withdrawing because of an adverse event. These results and the good spectrum of antibacterial activity make moxifloxacin a promising and also safe alternative for the empirical treatment of AECB.

Bacteria, antibiotics and COPD

Bacterial infection is one of several important causes of exacerbations of chronic obstructive pulmonary disease (COPD) that may coexist. COPD is a heterogeneous condition and the incidence of bacterial infection is not uniform; mucus hypersecretion may be an important risk factor. The bacteriology of infections varies depending on the severity of the underlying airway disease. There is now a much better understanding of the pathogenesis of bacterial infections of the respiratory mucosa. Lower airway bacterial colonization may be a stimulus for chronic inflammation and may influence the interval between exacerbations. Antibiotic resistance has increased in all the major pathogens. Antibiotics are an important part of the treatment of acute exacerbations of COPD and the decision about whether to give an antibiotic can be made on clinical grounds. It is more difficult to decide, on the available evidence, whether patient characteristics and the risk of antibiotic resistance should influence choice of empiric antibiotic treatment. Most new antibiotics are modifications of existing structures, suggesting that every effort should be made to conserve the sensitivity of current antibiotics by using them appropriately.

Antibiotic drug prescription in respiratory tract infections: a pharmacoepidemiological survey among general practitioners in a region of Italy

Data concerning patients undergoing antibiotic treatment for upper (URTI) or lower (LRTI) respiratory tract infections were collected from 23 General Practitioners (GPs) in the Campania Region of Italy from November 15, 1997 to March 15, 1998. The objectives of the study were: a) to assess the occurrence of URTIs and LRTIs; b) to document the factors that influence GPs' choice of therapy; c) to correlate antibiotic choice with duration and outcome of treatment; d) to assess the incidence of unwanted effects. 2198 questionnaires were collected. Patients were +/-43.9 of age. URTIs were diagnosed in 65.4% and 34.6% LRTIs. The mean duration of antibiotic treatment was 4.5 days in URTIs and 5.6 days in LRTIs. The choice of antibiotic treatment was influenced by clinical assessment of infections (67.1%). The most commonly used antibiotic categories in URTIs were macrolides (39.3%), penicillins (27.4%) and cephalosporins (23.8%) whereas for LRTIs mainly cephalosporins (63.8%), penicillins (9.2%) and fluoroquinolones (7.4%) were used. Adverse events were experienced by 3.9% of patients.

Five day moxifloxacin therapy compared with 7 day clarithromycin therapy for the treatment of acute exacerbations of chronic bronchitis

In this multinational, randomized, double-blind study, the efficacy and safety of a 5 day course of moxifloxacin 400 mg orally od was compared with that of a 7 day course of clarithromycin 500 mg orally bd. in 750 patients with acute exacerbations of chronic bronchitis, characterized by at least two of the symptoms: sputum purulence, increased sputum volume or increased dyspnoea. Seven days after the end of therapy, clinical cure was achieved for 89% (287 of 322) of efficacy-evaluable patients in the moxifloxacin group and 88% (289 of 327) of patients in the clarithromycin group (95% CI, -3.9%, 5.8%). At follow-up (21-28 days post-treatment), the continued clinical cure rates were 89% (256 of 287) for moxifloxacin and 89% (257 of 289) for clarithromycin. A total of 342 pathogenic bacteria were isolated from the sputum of 287 patients. The most common pathogens were Haemophilus influenzae (37%), Streptococcus pneumoniae (31%) and Moraxella catarrhalis (18%). Seven days post-treatment, a successful bacteriological response was obtained for 77% (89 of 115) of patients in the moxifloxacin group and 62% (71 of 114) of patients in the clarithromycin group, indicating superiority of moxifloxacin (95% CI, 3.6%, 26.9%). Both treatments were well tolerated with few adverse events. This study demonstrated that for the treatment of acute exacerbations of chronic bronchitis a 5 day course of moxifloxacin 400 mg od was clinically equivalent and bacteriologically superior to a 7 day course of clarithromycin 500 mg bd.