musc.edu

OBJECTIVE: To analyze the cost and effectiveness of different antibiotic combinations for the treatment of infection with Chlamydia trachomatis in pregnant women. METHODS: Using availability treatment effectiveness rates from the literature, a decision analysis model was constructed to determine the effectiveness and cost of therapy with 4 antibiotics shown to be useful for Chlamydia infection during pregnancy. Women who were still infected after initial therapy were then treated with a second antibiotic. Outcomes included the total cost of the treatment (including pretreatment and posttreatment cultures and antibiotic cost) and treatment failure rates. RESULTS: The lowest failure rates could be achieved with the use of amoxicillin followed by azithromycin [Zithromax] for treatment failures or azithromycin [Zithromax] followed by clindamycin hydrochloride. When costs were compared, a strategy starting with amoxicillin followed by azithromycin [Zithromax] for nonresponders was favored, with costs approximately 15% lower than starting with azithromycin [Zithromax] followed by amoxicillin. Strategies using clindamycin were significantly more expensive. The drug combination recommended by the Centers for Disease Control and Prevention (erythromycin followed by amoxicillin in nonresponders) was more expensive than amoxicillin-azithromycin [Zithromax] and had one of the highest failure rates. Variation in the cost of the medications and in the effectiveness of the antibiotics under consideration did not significantly alter the findings. CONCLUSIONS: For pregnant women infected with Chlamydia, initiating treatment with amoxicillin, 500 mg 3 times a day for 7 days, followed by a single 1-g dose of azithromycin [Zithromax] for nonresponders is the most cost-effective strategy for treatment.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9371049&dopt=Abstract Zithromax azithromycin




Rev Med Chir Soc Med Nat Iasi. 1998 Jul-Dec;102(3-4):130-3.
[The postantibiotic effect of azithromycin [Zithromax] on respiratory pathogens]

[Article in Romanian]

Diculencu D, Andrews JM, Boswell FJ, Wise R.

Laboratorul de Microbiologie, Spitalul Clinic de Pneumoftiziologie, Iasi.

We assessed the post-antibiotic effect (PAE) of azithromycin [Zithromax] against 3 strains of Streptococcus pneumoniae 2 strains of Haemophilus influenzae and 2 strains of Moraxella catarrhalis. The strains were exposed for 2 hours to a concentration of 0.5 mg/l. A stationary phase inoculum of 1 x 10(6)-5 x 10(6) CFU/ml in IsoSensitest Broth with 5% lysed horse blood and 20 mg/l NAD was used and shaken for the duration of the experiment. Antibiotic was neutralised by dilution 1:1000 into pre-warmed medium. [table: see text] In conclusion, even at such low concentration as achieved in serum, azithromycin [Zithromax] has a PAE against the respiratory pathogens studied. In our opinion this could allow the use of azithromycin, in the usual regimen even in bacteremic respiratory infections.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10756861&dopt=Abstract Zithromax azithromycin




J Infect Dis. 1998 Jan;177(1):161-6.
Enhanced control of an outbreak of Mycoplasma pneumoniae pneumonia with azithromycin [Zithromax] prophylaxis.

Klausner JD, Passaro D, Rosenberg J, Thacker WL, Talkington DF, Werner SB, Vugia DJ.

Division of Bacterial and Mycotic Disease, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.

There are currently no recommended epidemic-control measures for Mycoplasma pneumoniae pneumonia outbreaks in closed communities. Previous studies have suggested the usefulness of chemoprophylaxis administered to close contacts of case-patients. To evaluate the effectiveness of various epidemic-control measures during an institutional outbreak, an observational study was undertaken during a very large outbreak of M. pneumoniae pneumonia at a facility for developmentally disabled residents (n = 142 cases). Control measures evaluated included no control, standard epidemic-control measures, and targeted azithromycin [Zithromax] prophylaxis (500 mg on day 1, 250 mg/day on days 2-5) plus standard epidemic-control measures. The combined use of azithromycin [Zithromax] prophylaxis and standard epidemic-control measures was associated with a significant reduction in the secondary attack rate. This study suggests that the addition of antibiotic prophylaxis to standard epidemic-control measures can be useful during institutional outbreaks of M. pneumoniae pneumonia.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9419183&dopt=Abstract Zithromax azithromycin




J Antimicrob Chemother. 1997 Nov;40(5):653-7.
Antimicrobial interference of a subinhibitory concentration of azithromycin [Zithromax] on fimbrial production of Porphyromonas gingivalis.

Lo Bue AM, Rossetti B, Cali G, Nicoletti G, Condorelli F.

Institute of Microbiology, University of Catania, Italy.

The first pathogenic mechanism of Porphyromonas gingivalis, which is mainly responsible for adult periodontal diseases, is the attachment of fimbriae appendages to oral epithelial cells. The ability of a subinhibitory concentration of azithromycin [Zithromax] to inhibit the expression of fimbriae in various strains of P. gingivalis isolated was investigated. A one-eighth subinhibitory concentration of azithromycin [Zithromax] was evaluated in vitro. The antibiotic was active in 75% of P. gingivalis strains isolated, judged by both electrophoresis and transmission electron microscopy. The results indicate that the subinhibitory concentration of azithromycin [Zithromax] is capable of blocking the pathogenic mechanism of P. gingivalis in vitro, and, therefore, can be used in vivo as a treatment for recurrent periodontitis.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9421312&dopt=Abstract Zithromax azithromycin




Curr Microbiol. 1998 Feb;36(2):119-23.
Azithromycin [Zithromax] and clarithromycin inhibition of 50S ribosomal subunit formation in Staphylococcus aureus cells.

Champney WS, Burdine R.

Department of Biochemistry and Molecular Biology, J.H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN 37614, USA.

The ID50 values for azithromycin [Zithromax] and clarithromycin inhibition of translation and of 50S assembly in Staphylococcus aureus cells have been measured. For clarithromycin, 50% inhibition of growth occurred at 0.075 microg/ml, and the effects on translation and 50S formation were equivalent at 0.15 microg/ml. The inhibition of these processes by azithromycin [Zithromax] was less effective, with an ID50 of 2.5 microg/ml for growth and 5 microg/ml for inhibition of translation and 50S formation. The additive effects of each of these drugs on translation and 50S formation account quantitatively for their observed influence on cellular growth rates. In macrolide-treated cells, there was also a direct relationship between the loss of ribosomal RNA from the 50S subunit and its accumulation as oligoribonucleotides. These results are compared with the previously described effects of erythromycin on these same processes.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9425251&dopt=Abstract Zithromax azithromycin




J Periodontol. 1997 Dec;68(12):1206-9.
Periodontal tissue disposition of azithromycin.

Malizia T, Tejada MR, Ghelardi E, Senesi S, Gabriele M, Giuca MR, Blandizzi C, Danesi R, Campa M, Del Tacca M.

Dipartimento di Biomedicina Sperimentale, Infettiva e Pubblica, Facolta di Medicina e Chirurgia, Universita di Pisa, Italy.

The tissue penetration of azithromycin, the prototype of a new class of macrolide antibiotics named azalides, was studied in patients undergoing surgery for third-molar removal. Drug concentrations in plasma, saliva, and periodontal tissues were evaluated in 28 patients treated with azithromycin [Zithromax] 500 mg/day per os for 3 consecutive days. Samples of blood, saliva, gingiva, and alveolar bone were collected during oral surgery, 12 hours, and 2.5, 4.5, and 6.5 days after the last dosing, and the azithromycin [Zithromax] concentration was measured microbiologically by using Micrococcus luteus NCTC 8440 as the reference organism. The highest concentrations of azithromycin [Zithromax] were observed 12 hours after the last dose in plasma, saliva, gingiva, and bone (0.33 +/- 0.04 mg/l, 2.14 +/- 0.30 mg/l, 6.47 +/- 0.57 mg/kg, and 1.86 +/- 0.15 mg/kg, respectively) and then declined gradually. However, consistent levels of the drug in saliva and periodontal tissues could be detected up to 6.5 days, indicating that azithromycin [Zithromax] was retained in target tissues and fluids for a long time after the end of treatment. Among the samples examined, the highest concentration of azithromycin [Zithromax] was found in the gingiva at each time studied. Moreover, the ratios of salivary or periodontal tissue levels versus plasma concentrations remained nearly unmodified from 12 hours up to 6.5 days. Overall, these results indicate a favorable disposition of azithromycin [Zithromax] into saliva and periodontal tissues and suggest that this macrolide antibiotic represents a valuable option in the pharmacologic treatment of odontogenic infections.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9444596&dopt=Abstract Zithromax azithromycin




Eur J Clin Microbiol Infect Dis. 1997 Nov;16(11):846-8.
Potentiation of antifungal activity of amphotericin B by azithromycin [Zithromax] against Aspergillus species.

Nguyen MH, Clancy CJ, Yu YC, Lewin AS.

Department of Medicine, University of Florida College of Medicine, and VA Medical Center, Gainesville 32610, USA.

The potential role of azithromycin [Zithromax] in combination with amphotericin B against 25 clinical isolates of Aspergillus was assessed. The MIC of amphotericin B was 1 microg/ml for 44% of the isolates, 0.5 microg/ml for 48%, and 0.25 microg/ml for 8%. All isolates were resistant to azithromycin. Synergism, defined as a > or = twofold reduction in the MIC of both drugs upon combination, was demonstrated between amphotericin B and azithromycin [Zithromax] for all 25 isolates. To prove that azithromycin [Zithromax] exerts its antifungal effect by inhibiting protein synthesis, we studied [35S]-methionine incorporation into protein in one Aspergillus isolate. Neither amphotericin B at 0.125 microg/ml (fourfold below its MIC) nor azithromycin [Zithromax] at 16 microg/ml (> or = 16-fold below its MIC) had any effect on protein synthesis when tested alone. Upon combination, however, a 68% inhibition in protein synthesis was evident by the inhibition of [35S]-methionine incorporation.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9447909&dopt=Abstract Zithromax azithromycin