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PubMed2000

Antibiotic prophylaxis for intrauterine contraceptive device insertion.

BACKGROUND: Concern about the risk of upper genital tract infection (pelvic inflammatory disease) often limits use of the IUD, a highly effective contraceptive. Prophylactic antibiotic administration around the time of induced abortion significantly reduces the risk of postoperative endometritis.(Sawaya, 1996) Since the risk of IUD-related infection is limited to the first few weeks to months after insertion,(Lee, 1983; Farley, 1992) contamination of the endometrial cavity at the time of insertion(Mishell, 1966) appears to be the mechanism, rather than the IUD or string itself. Thus, antibiotic administration before IUD insertion might reduce the risk of upper genital tract infection from passive introduction of bacteria at insertion. OBJECTIVES: To assess the effectiveness of prophylactic antibiotic administration before IUD insertion in reducing IUD-related complications and discontinuations within three months of insertion. The primary outcome was pelvic inflammatory disease (four reports) or early removals of the device (two reports). SEARCH STRATEGY: We searched both MEDLINE and EMBASE, handsearches of journals through CENTRAL, and lists of references. We also wrote to international experts in the field to identify unpublished studies. SELECTION CRITERIA: We included randomized controlled trials using any antibiotic compared with a placebo. We found four such trials; two had pilot study data available. DATA COLLECTION AND ANALYSIS DATA EXTRACTION: We used searches of MEDLINE, EMBASE, and handsearches of journals available through CENTRAL. We also reviewed lists of references in original research and in review articles. We wrote to experts to identify unpublished trials and made telephone calls to authors to supply missing information. Two independent reviewers abstracted data. We assessed the validity of each study using methods suggested in the Cochrane Handbook. DATA SYNTHESIS: We generated 2x2 tables for the principal outcome measures. We used the Peto modified Mantel-Haenszel technique to calculate odds ratios and assessed statistical heterogeneity between studies. MAIN RESULTS: The odds ratios for pelvic inflammatory disease associated with use of prophylactic doxycycline or azithromycin compared with placebo or no treatment was 0.89 (95%CI 0.53-1.51). Use of prophylaxis was associated with a small reduction in unscheduled vists to the provider (OR 0.82; 95% CI 0.70-0.98). Use of doxycycline or azithromycin had little effect on the likelihood of removal of the IUD within 90 days of insertion (OR 1.05; 95% CI 0.68-1.63). Significant heterogeneity did not exist between studies. REVIEWER'S CONCLUSIONS: Use of either doxycycline 200 mg or azithromycin 500 mg by mouth before IUD insertion confers little benefit. While the reduction in unscheduled visits to the provider was marginally significant, the cost-effectiveness of routine prophylaxis remains questionable. A uniform finding in these trials was the low risk of IUD-associated infection, with or without use of antibiotic prophylaxis.

Antibiotic Prophylaxis↗
PubMed2004

Effects of eight antibacterial agents on cell survival and expression of epithelial-cell- or cell-adhesion-related genes in human gingival epithelial cells.

OBJECTIVE AND BACKGROUND: Our previous studies suggest that little adverse effect on the growth of the periodontal ligament would be expected, if tetracycline, minocycline, ofloxacin, roxithromycin, clarithromycin, and azithromycin were topically administered to the periodontal pocket at their MIC90 doses required to inhibit the growth of 90% of periodontopathic bacteria, including Porphyromonas gingivalis, Prevotella intermedia, and Actinobacillus actinomycetemcomitans. In the present study, we investigated the cytocidal effects of eight antibacterial agents on the human gingival epithelial cell line NDUSD-1. We also used NDUSD-1 cells to examine the effects of these agents on the mRNA and protein expressions of genes associated with the proliferation, differentiation, or cellular adhesion important to the epithelial regeneration of the periodontal attachment. METHODS: The cytocidal effect of the test agents was measured as a decrease in cell survival. To obtain a quantitative measure of the cytocidal effect, the LD50, i.e. the concentration which results in a 50% decrease in cell survival relative to the controls, was extrapolated from the concentration-response curves. The effects of the agents on the mRNA and protein expressions in NDUSD-1 cells were studied by reverse transcription-polymerase chain reaction (RT-PCR) and western blot analyses, respectively. RESULTS: The cytocidal effect increased in a concentration-dependent manner as the concentration of each of the eight test agents increased. The order of the agents according to their cytocidal effects (LD50) was minocycline > tetracycline > enoxacin > clarithromycin > roxythromycin approximately ofloxacin > azithromycin > erythromycin. The cytocidal effects of minocycline, tetracycline, enoxacin, clarithromycin, roxythromycin, ofloxacin, and azithromycin ranged from 1.2 to 23.2 times greater than that of erythromycin. The maximum non-cytocidal concentrations (MNCCs) of these agents for NDUSD-1 cells were: 0.3 microm for minocycline, 1 microm for tetracycline, 3 microm for ofloxacin and erythromycin, 10 microm for enoxacin, clarithromycin, and azithromycin, and 100 microm for roxythromycin. The MNCCs of ofloxacin, azithromycin, clarithromycin, and roxythromycin were greater than their MIC90 concentrations for periodontopathic bacteria described above. The effects on the mRNA and protein expressions of epithelial-cell- or cell-adhesion-related genes were examined in NDUSD-1 cells exposed to clarithromycin, roxythromycin, ofloxacin, and azithromycin at their MNCCs. None of the agents affected the mRNA expressions of five genes: keratinocyte growth factor receptor, keratin 18, integrin beta1, integrin beta4, and laminin 5gamma2. Clarithromycin and ofloxacin slightly decreased the protein expression of integrin beta4. Roxythromycin markedly decreased the protein expressions of integrin beta4 and laminin 5gamma2. Azithromycin had little inhibitory effects on the protein expressions of any of the five genes. CONCLUSIONS: These results suggest that little, if any, adverse effects on growth, differentiation, and adhesion of basal epithelial cells would be expected with topical administration of clarithromycin, ofloxacin or azithromycin to the periodontal pocket at a dose equivalent to the MIC90. It is important to note, however, that the extrapolation of these findings to in vivo conditions has yet to be undertaken.

Anti-Bacterial Agents↗
PubMed1999

The role of newer macrolides in the treatment of community-acquired respiratory tract infection. A review of experimental and clinical data.

The macrolide class of antibiotics is well established and often recommended for use in the treatment of community-acquired respiratory tract infection (RTI). The newer agents clarithromycin and azithromycin are frequently prescribed as first- or second-line therapy, and have been considered as superior to erythromycin in microbiological activity and clinical efficacy. In-vitro data show that clarithromycin and azithromycin have good activity (MIC < or = 0.5 microg/ml) against certain RTI pathogens. However the activity of both compounds is intrinsically low against Haemophilus influenzae whilst several other important RTI pathogens - notably Streptococcus pneumoniae and Streptococcus pyogenes - exhibit a high prevalence of resistance to them. In many countries, the prevalence of resistance to clarithromycin and azithromycin is still rising with cross resistance with erythromycin. Maximum serum concentrations of clarithromycin and azithromycin are lower than the MIC90s for these agents against H. influenzae and S. pneumoniae. Concentrations in tissues have been reported to be much higher than those in serum. However, the high concentrations observed in tissues are largely a reflection of high concentrations inside cells. Concentrations of clarithromycin and azithromycin in extracellular tissue fluids, where Haemophilus and streptococci are located, are in equilibrium with concentrations in the serum, and remain low. It has been suggested that phagocytes deliver azithromycin to infection sites in a targeted fashion, but the evidence in support of this hypothesis is weak. Recent clinical experience with clarithromycin and azithromycin is consistent with preclinical results, and suggests that these agents have limited efficacy against certain respiratory infections. Clarithromycin and azithromycin are the first choice treatment of atypical infections caused by intracellular pathogens. For community-acquired RTIs, where H. influenzae and S. pneumoniae are present, they may no longer be an appropriate choice for first-line therapy. Indeed, in areas where levels of drug resistant S. pneumoniae are high, their use may be questionable as second-line therapy.

Anti-Bacterial Agents↗
PubMed1997

Prevention strategies for Mycobacterium avium-intracellulare complex (MAC) infection. A review of recent studies in patients with AIDS.

In patients with AIDS, disseminated Mycobacterium avium-intracellulare complex (MAC) infection is a common bacterial infection and is associated with considerable morbidity and mortality. In placebo-controlled studies, rifabutin, clarithromycin and azithromycin (administered as single agents) have been shown to prevent the development of MAC bacteraemia in patients with advanced HIV disease. Clarithromycin also conferred a survival benefit over placebo, but this was not initially observed with either rifabutin or azithromycin. Subsequently, the efficacy of single agent therapy was compared with that of combination treatment as prophylaxis against the development of disseminated MAC. In the AIDS Clinical Trials Group (ACTG) 196/Community Programs for Clinical Research on AIDS (CPCRA) 009 study, clarithromycin monotherapy and clarithromycin and rifabutin combination therapy regimens were both more effective than rifabutin monotherapy in reducing the incidence of MAC bacteraemia. However, the combination regimen was generally not well tolerated. In the California Consortium Treatment Group (CCTG)/Multiple Opportunistic Prevention Prophylactic Strategy (MOPPS) study, azithromycin plus rifabutin was significantly more effective than either agent administered alone, and azithromycin was more effective than rifabutin. However, azithromycin (alone or in combination with rifabutin) caused frequent gastrointestinal adverse events. Emergence of resistance in those failing prophylaxis appeared to be higher with clarithromycin than with azithromycin or rifabutin. The use of the combination regimen of clarithromycin plus rifabutin did not reduce the selection of clarithromycin-resistant isolates. Several issues need to be considered in the choice of MAC prophylaxis for the individual patient. On the basis of efficacy and potential drug interactions with protease inhibitors, clarithromycin or azithromycin is preferred to rifabutin. However, rifabutin is less likely to result in the emergence of resistance than the macrolides, and is likely to prevent tuberculosis, whereas azithromycin and clarithromycin will prevent some bacterial infections. Combination therapy for prophylaxis is not indicated in most situations.

AIDS-Related Opportunistic Infections↗
PubMed1991

Tissue-directed pharmacokinetics.

Azalide antibiotics demonstrate pharmacokinetics distinct from all antibacterial agents in common use. Following oral absorption, conventional oral antibiotics diffuse through serum and interstitial compartments and are eliminated rapidly. A minimal to moderate degree of intracellular penetration may be observed. The pharmacokinetics of azithromycin, the first azalide, are characterized by a rapid and extensive movement of the drug from the serum into intracellular compartments. A dynamic equilibrium exists between the intracellular, interstitial, and serum compartments, with predominant flux into tissue sites. Azithromycin is concentrated to a high degree within phagocytes and transported by chemotactic mechanisms to the site of infection. High concentrations of azithromycin are found in pulmonary, genital, and lymphatic tissues. Azithromycin's serum levels decline in a polyphasic manner with a terminal half-life of approximately 60 hours. These kinetics allow azithromycin to be administered once daily. It is predicted that after drug administration for 5 days, therapeutic levels of azithromycin will be maintained at the tissue sites of infection for an additional 4-7 days. Consideration of the extravascular pharmacodynamics of azithromycin is necessary when making predictions regarding its therapeutic application.

Animals↗
PubMed2005

Secondary prevention of atherosclerosis through chlamydia pneumoniae eradication (SPACE Trial): a randomised clinical trial in patients with peripheral arterial disease.

BACKGROUND: Sero-epidemiological and experimental studies suggest that Chlamydia pneumoniae infections play an important role in the development of atherosclerosis. Clinical trials have shown contradictory results regarding the efficacy of antibiotics to prevent atherosclerosis-related complications in patients with coronary artery disease. Our aim was to study the effect of a short course of azithromycin on the incidence of cardiovascular events and peripheral vascular function in patients with stable peripheral arterial disease (PAD). PATIENTS AND METHODS: Five hundred and nine PAD-patients were randomised to receive either a 3-day course of azithromycin (500 mg daily) or placebo, with 2 years of follow-up. C. pneumoniae serology was determined at baseline. Clinical endpoints were death, coronary events (myocardial infarction, unstable angina, and/or coronary revascularization procedures), cerebral events (stroke, TIA, and/or carotid endarterectomy) and peripheral arterial complications (increased PAD-symptoms with decreased ankle-brachial index (ABPI, 0.1-point decrease after 12 months), and/or peripheral revascularization procedures). RESULTS: Five hundred and nine patients (160 women) with an atherosclerotic risk factor profile were randomised, 257 patients to azithromycin and 252 to placebo. Four hundred and forty nine patients (88%) had intermittent claudication and 60 (12%) had critical limb ischemia. By 24-month follow up, 182 patients (36%) developed 252 complications (45 deaths, 34 coronary events, 34 cerebral events and 139 peripheral arterial complications). C. pneumoniae IgA-titres were associated with the development of cardiovascular events. Nevertheless, the number of complications (131 in the azithromycin group vs. 121 in the placebo group) and the number of patients that developed complications (98 (38%) in the azithromycin vs. 84 (33%) in the placebo group) was comparable in both treatment groups. Life table analysis showed no effect of azithromycin on survival or ABPI. CONCLUSION: A short-term course of azithromycin offers no benefits for survival or ankle pressure in PAD-patients.

Aged↗
PubMed1996

Incidence of antibiotic-resistant Streptococcus pneumoniae and beta-lactamase-positive Haemophilus influenzae in clinical isolates from patients with otitis media.

BACKGROUND: The prevalence of penicillin-resistant Streptococcus pneumoniae and beta-lactamase-producing Haemophilus influenzae in otitis media infections is increasing; emergence of these pathogens has complicated treatment. OBJECTIVES: To evaluate the incidence of penicillin resistance and the in vitro activity of amoxicillin/clavulanate, cefaclor, loracarbef, cefixime, trimethoprim/sulfamethoxazole, azithromycin and clarithromycin in S. pneumoniae isolates. The in vitro activity of azithromycin, clarithromycin and cefaclor was also evaluated in beta-lactamase-positive and -negative isolates of H. influenzae. METHODS: Bacterial isolates of S. pneumoniae and H. influenzae were obtained by tympanocentesis and subsequent culture of middle ear effusion from children with acute otitis media enrolled in a multicenter trial. Susceptibility to test agents was assessed by disk diffusion and broth dilution techniques with criteria established by the National Committee for Clinical Laboratory Standards. RESULTS: Nineteen (31%) of the 61 S. pneumoniae isolates were resistant to penicillin. A significantly lower percentage of the S. pneumoniae isolates were resistant to azithromycin (16%) and clarithromycin (11%) than to penicillin, amoxicillin/ clavulanate, cefaclor, loracarbef or cefixime (31% in all cases). Azithromycin was also more active than cefaclor and significantly more active than clarithromycin against the 55 H. influenzae isolates. CONCLUSIONS: The susceptibility of resistant and nonresistant strains of S. pneumoniae to azithromycin and clarithromycin and of isolates of H. influenzae to azithromycin, coupled with penetration of azithromycin into the middle ear, may provide a significant advantage in the treatment of otitis media.

Anti-Bacterial Agents↗
PubMed2004

The use of macrolide antibiotics in patients with cystic fibrosis.

PURPOSE OF REVIEW: There has been much recent interest in the use of macrolide antibiotics as chronic suppressive therapy in patients with cystic fibrosis. Three recent randomized, placebo-controlled trials have been conducted. RECENT FINDINGS: All three trials used similar regimens of azithromycin, and lung function improved after 3 to 6 months of treatment. The relative change in forced expiratory volume in 1 second predicted improved between 3.6% and 6.2%. Furthermore, the azithromycin treatment groups had improvement in a variety of secondary outcomes related to pulmonary exacerbations, including a reduction in antibiotic use (both intravenous and oral) and hospitalization rate. Furthermore, azithromycin was well tolerated: Only nausea, diarrhea, and wheezing (described as mild to moderate) occurred more frequently in the azithromycin group compared with the placebo group. The evidence for the clinical benefit of azithromycin in cystic fibrosis has been summarized in a Cochrane review in which a meta-analysis confirmed a significant improvement in forced expiratory volume in 1 second among the 286 pooled participants. SUMMARY: Azithromycin has entered the therapeutic armamentarium for patients with cystic fibrosis who are chronically infected with Pseudomonas aeruginosa. Improved lung function, a reduction in pulmonary exacerbations and antibiotic use, and weight gain are potential benefits of this drug. Future studies should address the use of azithromycin in other cystic fibrosis patient populations, including those patients without chronic infection with P. aeruginosa, children younger than 6 years of age, and those infected with Burkholderia cepacia complex. The mechanism of action of macrolide antibiotics in cystic fibrosis remains unknown.

Anti-Bacterial Agents↗
PubMed2006

An observational cohort study of Chlamydia trachomatis treatment in pregnancy.

BACKGROUND AND OBJECTIVES: Currently, azithromycin is not considered a first-line treatment for Chlamydia trachomatis in pregnant women. We evaluated the use, efficacy, and safety of azithromycin compared with erythromycin and amoxicillin in the treatment of genital chlamydial infection during pregnancy. METHODS: This was a retrospective cohort study of pregnant women with genital chlamydial infection. Data on antibiotics prescribed, test-of-cure (TOC) results, and maternal and infant complications were collected from medical records. RESULTS: Of the 277 women in the study sample, 69% were initially prescribed azithromycin, 9% amoxicillin, and 19% erythromycin. Eight-one percent of subjects had a TOC 7 or more days after diagnosis and before delivery. Treatment efficacy, as defined by a negative TOC, was 97% (95% confidence interval [CI], 92.9-99.2) for azithromycin, 95% (95% CI, 76.2-99.9) for amoxicillin, and 64% (95% CI, 44.1-81.4) for erythromycin. The efficacy of azithromycin was significantly higher than erythromycin (P < 0.0001). There were no significant differences in efficacy by age, race/ethnicity, concurrent sexually transmitted disease diagnosis, partner treatment, or substance use. Furthermore, there was no difference in complications for women or infants exposed to azithromycin compared with those treated with other regimens. CONCLUSION: Clinical outcome data from this study population of women and infants support both efficacy and safety of azithromycin for treatment of C. trachomatis in pregnancy.

Amoxicillin↗
PubMed2002

Divergent proarrhythmic potential of macrolide antibiotics despite similar QT prolongation: fast phase 3 repolarization prevents early afterdepolarizations and torsade de pointes.

Macrolide antibiotics are known to have a different proarrhythmic potential in the presence of comparable QT prolongation in the surface ECG. Because the extent of QT prolongation has been used as a surrogate marker for cardiotoxicity, we aimed to study the different electrophysiological effects of the macrolide antibiotics erythromycin, clarithromycin, and azithromycin in a previously developed experimental model of proarrhythmia. In 37 Langendorff-perfused rabbit hearts, erythromycin (150-300 microM, n = 13) clarithromycin (150-300 microM, n = 13), and azithromycin (150-300 microM, n = 11) led to similar increases in QT interval and monophasic action potential (MAP) duration. In bradycardic (atrioventricular-blocked) hearts, eight simultaneously recorded epi- and endocardial MAPs demonstrated increased dispersion of repolarization in the presence of all three antibiotics. Erythromycin and clarithromycin led to early afterdepolarizations (EADs) and torsade de pointes (TdP) after lowering of potassium concentration. In the presence of azithromycin, no EAD or TdP occurred. Erythromycin and clarithromycin changed the MAP configuration to a triangular pattern, whereas azithromycin caused a rectangular pattern of MAP prolongation. In 13 additional hearts, 150 microM azithromycin was administered after previous treatment with 300 microM erythromycin and suppressed TdP provoked by erythromycin. In conclusion, macrolide antibiotics lead to similar prolongation of repolarization but show a different proarrhythmic potential (erythromycin > clarithromycin > azithromycin). In the presence of azithromycin, neither EAD nor TdP occur. This effect may be related to a rectangular pattern of action potential prolongation, whereas erythromycin and clarithromycin cause triangular action potential prolongation and induce TdP.

Animals↗
PubMed1998

Emergence of Mycobacterium avium populations resistant to macrolides during experimental chemotherapy.

Macrolide resistance is an emerging problem in AIDS patients who receive these agents for treatment or prophylaxis against Mycobacterium avium (MAC) infection. We compared the emergence of resistant MAC strains during therapy with clarithromycin (clarithromycin resistance was defined as MIC > or = 32 microg/ml) and azithromycin (azithromycin resistance was defined as MIC > or = 128 microg/ml) in C57BL/6 beige mice. Treatment with clarithromycin and azithromycin resulted in a decrease of 98.5% in the number of viable bacteria in spleens at week 8 and 99% at week 12 compared with the number of bacteria present in spleen before the initiation of therapy (P < 0.001). Splenic homogenates were also plated onto 7H11 agar plus clarithromycin at 32 microg/ml or azithromycin at 128 microg/ml. Resistance emerged significantly more often in mice treated with clarithromycin (100% of treated mice at both 8 and 12 weeks) than in those receiving azithromycin (0% at week 8 and 14% at week 12). The frequencies of resistance of the MAC population in the spleen to clarithromycin were 2.1 x 10(-3) at week 8 and 1.1 x 10(-2) at week 12, whereas resistance to azithromycin was absent at week 8 (all mice) and was approximately 3.5 x 10(-5) (mean for the three positive animals) at week 12. Clarithromycin was more effective in initial reduction of MAC burden in tissue after 8 and 12 weeks of treatment, but resistant strains emerged significantly more frequently after treatment with clarithromycin than after treatment with azithromycin.

Animals↗