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Microbiologic and immunologic evaluation of a single high dose of azithromycin for treatment of experimental Mycoplasma pneumoniae pneumonia.

We evaluated the efficacy of azithromycin therapy given as a single high dose or divided over 5 days for the treatment of mild experimental Mycoplasma pneumoniae pneumonia. Although both azithromycin regimens significantly reduced quantitative cultures, lung histopathology, and pulmonary cytokines and chemokines, there were no significant differences between the two regimens.

Animals↗

Comparative in vitro activities of three new quinolones and azithromycin against aerobic pathogens causing respiratory tract and abdominal wound infections.

BACKGROUND: In our study the in vitro susceptibility of common pathogens that cause respiratory tract and abdominal wound infections was tested against two newer fluorquinolones (moxifloxacin and gatifloxacin) as well as levofloxacin and azithromycin. METHODS: 50 isolates each of methicillin-susceptible Staphylococcus aureus, Enterococcus faecalis, Enterococcus faecium, Streptococcus pneumoniae, Streptococcus pyogenes, Escherichia coli, Pseudomonas aeruginosa and Haemophilus influenzae isolated from the respiratory tract and from wounds were tested for their susceptibility to moxifloxacin, gatifloxacin, levofloxacin and azithromycin. RESULTS: Moxifloxacin proved to be the most active substance against the tested gram-positive pathogens. Gatifloxacin was the most active against P. aeruginosa. Moxifloxacin and gatifloxacin proved to be comparably active against the clinical isolates of E. coli and H. influenzae. CONCLUSIONS: Moxifloxacin and gatifloxacin display excellent activity against respiratory pathogens as well as nosocomial pathogens causing abdominal wound infections. When treating infections caused by P. aeruginosa the earlier fluorquinolones such as ciprofloxacin or ofloxacin are the substances of choice.

Abdominal Injuries↗

Effect of azithromycin, roxithromycin and erythromycin on human polymorphonuclear leukocyte function against Staphylococcus aureus.

The effect of three macrolides (azithromycin, roxithromycin and erythromycin) on the interaction in vitro of human polymorphonuclear leukocytes (PMNs) with Staphylococcus aureus was examined. The exposure of S. aureus to 0.25 MIC of roxithromycin and erythromycin but not of azithromycin significantly increased the uptake of opsonized bacteria by human PMNs. The preincubation of PMNs with 1, 10 and 25 mg/l of the three antimicrobial agents did not affect either the uptake of S. aureus or the superoxide radical production by human PMNs. At these same concentrations the three agents showed slight but not significant intracellular activity in PMNs against S. aureus. It is concluded that treatment of S. aureus with subinhibitory concentrations of roxithromycin and erythromycin enhanced phagocytosis by PMNs, but the three macrolides tested did not directly affect the functions of human PMNs against S. aureus.

Azithromycin↗

A new model examining intracellular and extracellular activity of amoxicillin, azithromycin, and clarithromycin in infected cells.

An in vitro infection model was created using a suspension of macrophages, polymorphonuclear leukocytes, lymphocytes, fibroblasts, and human serum to which pathogen and antibiotic were added. Separate intracellular and extracellular antibiotic concentrations and activity against Staphylococcus aureus and Legionella pneumophila were assessed for three antimicrobial agents: amoxicillin, azithromycin and clarithromycin. Amoxicillin was found almost exclusively in extracellular fluid, where it was active; intracellularly, it was ineffective. Azithromycin, in contrast, was primarily concentrated and active intracellularly, with little activity in extracellular fluid. Clarithromycin was present in both compartments and possessed significant activity both intracellularly and extracellularly.

Amoxicillin↗

Antibacterial activity of azithromycin against Brucella melitensis.

In vitro antibacterial activity of the new macrolide azithromycin was tested against 116 strains of Brucella melitensis, isolated from 115 patients in a major tertiary care referral center. Eighty-seven percent of the strains were inhibited by 1.0 mg/l and all the 116 strains by 2.0 mg/l of azithromycin. Comparison was made with tetracycline, gentamicin, trimethoprim-sulfamethoxazole, rifampicin and ciprofloxacin. All the isolates were susceptible to gentamicin, tetracycline, trimethoprim-sulfamethoxazole, rifampicin. One hundred and fifteen of the 115 strains were also susceptible to ciprofloxacin.

Anti-Bacterial Agents↗

Infection with Chlamydia pneumoniae accelerates the development of atherosclerosis and treatment with azithromycin prevents it in a rabbit model.

BACKGROUND: Chlamydia pneumoniae infection has been associated with atherosclerosis by serological studies and detection of bacterial antigen within plaque. We sought to evaluate a possible causal role in an animal model. METHODS AND RESULTS: Thirty New Zealand White rabbits were given three separate intranasal inoculations of either C pneumoniae (n = 20) or saline (n = 10) at 3-week intervals and fed chow enriched with a small amount (0.25%) of cholesterol. Immediately after the final inoculation, infected and control rabbits were randomized and begun on a 7-week course of azithromycin or no therapy. Three months after the final inoculation, rabbits were euthanatized and sections of thoracic aortas were blindly evaluated microscopically for maximal intimal thickness (MIT), percentage of luminal circumference involved (PLCI), and plaque area index (PAI) of atherosclerosis. Vascular chlamydial antigen was assessed by direct immunofluorescence. MIT differed among treatment groups (P=.009), showing an increase in infected rabbits (0.55 mm; SE = 0.15 mm) compared with uninfected controls (0.16 mm; SE = 0.06 mm) and with infected rabbits receiving antibiotics (0.20 mm; SE = 0.03 mm) (both P<.025), whereas MIT in infected/treated versus control rabbits did not differ. PLCI also tended to differ (P<.1) and PAI differed significantly (P<.01) among groups with a similar pattern. Chlamydial antigen was detected in 2 untreated, 3 treated, and 0 control animals. CONCLUSIONS: Intranasal C pneumoniae infection accelerates intimal thickening in rabbits given a modestly cholesterol-enhanced diet. In addition, weekly treatment with azithromycin after infectious exposure prevents accelerated intimal thickening. These findings strengthen the etiologic link between C pneumoniae and atherosclerosis and should stimulate additional animal and human studies, including clinical antibiotic trials.

Animals↗

Inhibition of intracellular growth of Staphylococcus aureus by exposure of infected human monocytes to clarithromycin and azithromycin.

The direct effect of clarithromycin and azithromycin on human polymorphonuclear leukocyte (PMN) functions and their intracellular activity against Staphylococcus aureus, phagocytosed by human monocytes, were studied. The presence of both antibiotics, in the range of concentrations from 0.25 to 20 micrograms/ml, did not affect chemotaxis, opsonized-zymosan phagocytosis, respiratory burst measured by nitroblue tetrazolium reduction and phorbol myristate acetate-induced superoxide production, or the microbicidal activity of human PMNs against Candida albicans. Both macrolides were bactericidal against staphylococci in the monocyte system, while bacteriostatic activity was found in cell free system. At concentrations equal to the minimum inhibitory concentrations (MICs) (0.75 and 0.1 respectively for azithromycin and clarithromycin) more than 99% of intraphagocytic S. aureus were killed after 24 h incubation. Increasing the concentrations of each drug above the MICs (5 and 10 MICs) did not alter the killing rate of intracellular bacteria. Moreover, no differences between the intracellular bioactivity of these antibiotics were demonstrated, despite their different uptake kinetics.

Azithromycin↗

Determination of the etiological organism during acute exacerbations of COPD and efficacy of azithromycin, ampicillin-sulbactam, ciprofloxacin and cefaclor. Turkish Thoracic Society COPD Working Group.

Acute exacerbations, most of which are due to lower respiratory tract infections, cause great morbidity and mortality in patients with chronic obstructive pulmonary disease (COPD) and most of these are due to lower respiratory tract infections. The aim of this study was to determine the causative organism and the effects of azithromycin, ampicillin sulbactam (sultamicillin), ciprofloxacin and cefaclor monohydrate therapy in COPD. One hundred and six patients with COPD in acute exacerbation were randomized into four groups for empiric antibiotic treatment following lung function tests and sputum examination. The most common strains isolated from sputum were Haemophilus influenzae (30.8%), Streptoccocus pneumoniae (12%) and Moraxella catarrhalis (7.7%). Azithromycin, sultamicillin, ciprofloxacin and cefaclor monohydrate were found to be effective in treating COPD exacerbations.

Ampicillin↗

Duration of clinical symptoms in female patients with acute urethral syndrome caused by Chlamydia trachomatis treated with azithromycin or doxycycline.

One hundred fifty-one female patients with acute urethral syndrome caused by Chlamydia trachomatis were examined. First, patients were divided into two groups, those with clinical symptoms present < 3 weeks before the start of treatment, and those with clinical symptoms > or = 3 weeks prior to the beginning of therapy. Then patients were further divided into groups and randomized to receive azithromycin once daily in a single dose of 1.0 g or 500 mg once daily for 6 days, or to receive doxycycline 100 mg b.i.d. for 14 days or 100 mg b.i.d. for 7 days (8 study groups in all). Clinical and bacteriological efficacy was evaluated 3 weeks after the end of therapy. In the group of patients with disease symptoms lasting for 3 weeks or longer, the eradication and clinical cure rates were significantly higher after administration of azithromycin in a dose of 1x500 mg/6 days than after a single dose of 1.0 g (p<0.01), and after administration of doxycycline 2x100 mg/14 days than by using doxycycline 2x100 mg/7 days (p<0.05).

Administration, Oral↗

Accumulation of azithromycin and roxithromycin in tracheal epithelial fetal cell lines expressing wild type or mutated cystic fibrosis transmembrane conductance regulator protein (CFTR).

Macrolides are accumulated in phagocytes, partially via an active transport system; the membrane carrier is not identified but many data indicate a link with the P-glycoprotein family which includes the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) protein. We have used two epithelial cell lines which express either wild-type (N cells) or mutated (homozygous deltaF508) (F cells) CFTR to study the cellular accumulation of two macrolides (azithromycin and roxithromycin). Adherent cells were incubated with the radiolabeled drugs before extensive washings and counting. Azithromycin was better (about 2-fold) accumulated in F cells up to 60 min but then plateaued, whereas accumulation continued without saturation over 3 hours in N cells. Roxithromycin was also better (1.5-fold) accumulated in F cells at 15 and 30 min, but there were no differences at further incubation times. Macrolide efflux from loaded N and F cells, and the susceptibilities of the carrier systems (entry and efflux) to various pharmacologic agents were similar to those previously observed with phagocytes. These data suggest that the macrolide carriers (for entry and efflux) are not strictly specific for phagocytes and that the CFTR protein plays a role in macrolide uptake.

Analysis of Variance↗

Pulmonary cryptosporidiosis in an AIDS patient: successful treatment with paromomycin plus azithromycin.

Extra-intestinal cryptosporidiosis, especially of the biliary and respiratory tract, is likely in the course of an intestinal involvement, whereas it is rare without such a localization. We report a case of pulmonary cryptosporidiosis without apparent intestinal involvement in an AIDS patient, with favourable outcome after antimicrobial combination therapy with paromomycin plus azithromycin. The successful response to antimicrobial treatment was subsequently maintained by effective highly active antiretroviral therapy (HAART). We suggest that respiratory cryptosporidiosis should be investigated in HIV-infected patients with pulmonary symptoms and low CD4 cell count, and, if detected, treatment should include HAART plus the combination of paromomycin and azithromycin.

AIDS-Related Opportunistic Infections↗

Azithromycin in gonorrhoea.

The clinical applications of azithromycin in gonorrhoea, often complicated by simultaneously acquired infection with Chlamydia trachomatis, are reviewed in this paper. Clinical trails from major centres in Europe are compared with a large, more recent US study. At the present time, azithromycin is recommended throughout the world as a useful antibiotic in treatment of gonorrhoea. It has several advantages in that it can be given as single-dose therapy, it can be given where the causative pathogen of urethritis/cervicitis is uncertain, and it is often, therefore, most useful in acute therapy where there is no immediate microbiological back-up. All these considerations are reviewed in detail.

Anti-Bacterial Agents↗

Azithromycin in the management of Chlamydia trachomatis infections.

The unique pharmacological profile of the azalide macrolide azithromycin, coupled with its in vitro activity against both Chlamydia trachomatis and the ureaplasmas, suggested that genital infections caused by these bacteria could be successfully treated with a single dose of the antibiotic. This has now been confirmed in worldwide clinical studies. A single oral dose of azithromycin 1 g eradicates C. trachomatis in almost 100% of cases of non-gonococcal urethritis and cervicitis. Unfortunately, there are no specific clinical signs for genital chlamydial infection. It is therefore necessary to use therapy effective against known and unknown pathogens for treating lower genital tract infection. Clinical cure rates for both chlamydial and non-chlamydial, non-gonococcal infections compare favourably with standard 7-day doxycycline therapy, being in excess of 85%. Side effects are few (< 20%) and essentially minor.

Anti-Bacterial Agents↗

Helicobacter pylori eradication using tetracycline and furazolidone versus amoxicillin and azithromycin in lansoprazole based triple therapy: an open randomized clinical trial.

BACKGROUND: Optimal anti-Helicobacter pylori treatment has not yet been established. AIM: To evaluate H. pylori eradication using tetracycline and furazolidone versus amoxicillin and azithromycin in lansoprazole based triple therapy in northeastern of Brazil. PATIENTS AND METHODS: One hundred and four patients with H. pylori infection, as determined by rapid urease testing and histology, were randomly assigned to receive either: lansoprazole (30 mg q.d.), tetracycline (500 mg q.i.d.), and furazolidone (200 mg t.i.d.) for 7 days (LTF; n = 52); or lansoprazole (30 mg b.i.d.) and amoxicillin (1 g b.i.d.) for 1 week, plus azithromycin (500 mg q.d.) for the first 3 days (LAAz; n = 52). H. pylori eradication was assessed 3 months following completion of therapy by means of rapid urease testing, histology and a 14C-urea breath test. RESULTS: H. pylori eradication was achieved in 46 of 52 (88.4%, 95% CI: 77.5%-95.1%) patients in LTF group and in 14 of 52 (26.9%, 95% CI: 16.2%-40,1%) patients in LAAz group. On a per-protocol analysis, eradication rates were 91.8% (95% CI: 81.4%-97.3%) and 28.5% (95% CI: 17.2%-42.3%), respectively in LTF and LAAz groups. CONCLUSION: The LAAz regimen yielded unacceptably low eradication rates. On the other hand, the LTF scheme represents a suitable alternative for H. pylori eradication.

2-Pyridinylmethylsulfinylbenzimidazoles↗

Efficacy of azithromycin in the treatment of cutaneous leishmaniasis.

The present open pilot study was conducted to assess the efficacy of azithromycin for the treatment of patients with cutaneous leishmaniasis in Ara ua and Varzelândia, MG. Twenty-four patients with less of six months of disease evolution were treated after clinical examination, Montenegro test and a biopsy. The treatment schemes consisted of oral doses of 500 mg per day for 3, 5 and 10 days and of 1000 mg for two days. A clinical control was performed monthly and treatment cycles were repeated when necessary until full reepithelialization of the lesions. On the occasion of the final evaluation, 20 patients had completed the study and 17 of them (85%) were cured. The time to obtain a cure was 60 days ifor 6 (30%) patients, 90 days for 7 (35%), and 120 for 4 (20%). The three patients with treatment failure received a pentavalent antimonial for 20 days. No adverse reactions to the medication were observed and a 14 month follow-up did not show recurrence in any patient. These results suggest that azithromycin can be a good therapeutic option for the treatment of cutaneous leishmaniasis caused by Leishmania Viannia brasiliensis.

Adolescent↗

Low efficacy of an ultra-short term, once-daily dose triple therapy with omeprazole, azithromycin, and secnidazole for Helicobacter pylori eradication in peptic ulcer.

PURPOSE: To determine the eradication rate of an ultra-short treatment schedule for Helicobacter pylori infection in a population with peptic ulcers, using omeprazole, secnidazole, and azithromycin in a once-daily dose for 3 days. METHODS: Thirty patients with peptic ulcer diagnosed by upper endoscopy and for Helicobacter pylori infection by rapid urease test and histologic examination received omeprazole 40 mg, secnidazole 1000 mg, and azithromycin 500 mg, administered once daily for 3 days. A follow-up exam was performed 12 weeks after the end of the treatment. Patients who were negative for Helicobacter pylori infection by rapid urease test and histologic examination were considered cured. RESULTS: Patients were predominantly female, and the mean age was 50 years. Duodenal peptic ulcer was found in 73% of the patients. Eradication was achieved in 9 of the 28 (32%) patients as determined from the follow-up endoscopic exam. The eradication rate by intention to treat was 30%. Side effects were present in 3% of the patients, and compliance to treatment was total. CONCLUSIONS: In spite of the low rate of side effects and good compliance, the eradication index was low. A possible drawback of this therapy is that it reduces the efficacy of macrolide and nitroimidazole compounds in subsequent treatments.

Adult↗

Efficacy of combined atovaquone and azithromycin for therapy of chronic Babesia gibsoni (Asian genotype) infections in dogs.

Babesiosis caused by Babesia gibsoni (Asian genotype) is an emerging disease in dogs in the United States. To date, no drugs have been shown to eliminate B. gibsoni (Asian genotype) infections from dogs. Twenty-two dogs that remained persistently infected with B. gibsoni (Asian genotype) after either imidocarb diproprionate and or diminazine aceturate therapy were identified and randomly and evenly distributed into 2 groups. One group was treated with atovaquone and azithromycin combination therapy, and the other group received a placebo. Eight of 10 dogs in the treatment group had no detectable B. gibsoni (Asian genotype) DNA, as determined by a sensitive and specific polymerase chain reaction (PCR) assay, in any of their posttreatment samples. In contrast, B. gibsoni (Asian genotype) DNA was detectable by PCR in the posttreatment samples from 11 of 11 of the placebo-treated dogs. One dog in the treatment group was excluded from the treatment outcome analysis. This dog had 2 consecutive negative PCR assay results and was euthanized because of ongoing degenerative joint disease prior to completion of the study. No adverse effects of treatment were reported in any dog during the study period. A combination of atovaquone and azithromycin is the 1st described treatment that will either eliminate B. gibsoni (Asian genotype) infections or suppress the parasitemia below the limit of detection in the majority of treated dogs.

Animals↗

Inhibition of cyclosporin A-induced gingival overgrowth by azithromycin through phagocytosis: an in vivo and in vitro study.

BACKGROUND: The objective of the present study was to investigate the effect of cyclosporin A (CsA) and azithromycin (AZI) on collagen metabolism in the gingiva of rats. METHODS: Fifty 6-week-old male Sprague-Dawley (SD) rats (weight 120 to 150 g) were randomly distributed into five groups. All groups received various drugs via gastric feeding for 7 weeks. The first group (Mo group) received mineral oil for 7 weeks as a control; the CsA group received CsA in mineral oil for 7 weeks (dosage 30 mg/kg); the CsA/Mo group received CsA in mineral oil for 6 weeks and mineral oil only for the seventh week; the CsA/AZI group received CsA in mineral oil for 6 weeks and AZI (dosage 10 mg/kg) in mineral oil simultaneously with CsA in the seventh week; and the Mo/AZI group received mineral oil for 6 weeks and AZI in mineral oil for the seventh week. All animals were sacrificed for clinical and histological analyses. Gingival fibroblasts were cultured at the fourth passage, and the amount of collagen was measured. Type I collagen and collagenase mRNA were measured by reverse transcription-polymerase chain reaction. Collagen phagocytosis assay also was performed. RESULTS: Clinically, CsA induced gingival overgrowth in rats, whereas AZI reduced gingival overgrowth. Histological results of the CsA group showed a marked increase of tissue volume compared to the other groups. High collagen amounts were found when gingival overgrowth was induced. However, type I collagen mRNA and collagenase mRNA expressions did not statistically differ among groups. Phagocytosis assay showed that CsA decreased phagocytic activity of gingival fibroblasts, whereas AZI increased the activity. These results suggest that the induction and reduction of CsA-induced gingival overgrowth were closely associated with phagocytic activity. CONCLUSION: Cyclosporin A decreases collagen degradation by lowering phagocytic activity of rat gingival fibroblasts. Azithromycin partially compensates for this lowered phagocytic activity.

Animals↗