Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Azithromycin”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16Linked to original sources
PubMed1993

A single-blind comparison of three-day azithromycin and ten-day co-amoxiclav treatment of acute lower respiratory tract infections.

The efficacy and safety of a three-day regimen of azithromycin (500 mg od) and a ten-day regimen of co-amoxiclav (625 mg tid) were compared in a single-blind study in 99 patients with acute lower respiratory tract infections. Of these, 70 (71%) suffered an infective exacerbation of their chronic obstructive pulmonary disease. Nine patients had pneumonia and 19 purulent bronchitis. Treatment success, defined as cure or improvement, occurred in 43 of 48 (90%) patients in the azithromycin group, compared with 45 of 51 (88%) patients in the co-amoxiclav group. The most common isolated pathogens were Haemophilus influenzae (25 cases; MIC range of azithromycin (A) < or = 0.06-4 mg/L; for co-amoxiclav (CA) 0.25-4 mg/L; Streptococcus pneumoniae (10 cases; A: < or = 0.06- > 128; CA: < or = 0.06); and Moraxella catarrhalis (four cases; A: < or = 0.06; CA: < or = 0.06-0.25). Microbiological response rates were comparable in the two groups. In 5% of patients, serological evidence for virus or atypical pathogens was found. Thirteen (26%) patients treated with co-amoxiclav had gastrointestinal complaints (seven with diarrhoea), compared with five (10%) treated with azithromycin (P = 0.09). Additional complaints occurred in three patients treated with co-amoxiclav and in one patient treated with azithromycin. It was concluded that a three-day regimen of azithromycin was as effective, clinically and microbiologically, as a ten-day regimen of co-amoxiclav in the treatment of acute lower respiratory tract infections.

Adult↗
PubMed1993

Comparison of azithromycin, roxithromycin, and cephalexin penetration kinetics in early and mature abscesses.

During the process of abscess formation, a myriad of changes are observed histologically that impede the penetration of antimicrobial agents into infection loci. A Staphylococcus aureus foreign body abscess, developed in rats, was employed to evaluate the penetration kinetics of azithromycin, roxithromycin and cephalexin at various stages of abscess development; the progressive patho-histological changes of abscess formation were also characterized in this model. In an early abscess (18 h post-challenge), azithromycin penetration into inflammatory fluid was enhanced (AUC of 351 vs 130 mg.h/kg) and residence prolonged relative to an inflammation control (half-life of 88 vs 27 h). In contrast, roxithromycin and cephalexin penetration into, and residence in, inflammatory fluid were unaltered in the early abscess. However, penetration into, and egress from, a mature abscess (ten days post-challenge) were impeded for all three antimicrobials (P < or = 0.03). The penetration kinetics of azithromycin into inflammatory fluid in an early abscess were independent of the dose regimen, but dependent on the total dose. The persistently high concentrations of azithromycin in inflammatory fluid within abscess were associated with the infiltration of phagocytic cells and encapsulation by fibrous tissue. These data are consistent with a phagocytic delivery mechanism for azithromycin, whereby the presence of high concentrations of azithromycin in inflammatory fluid are a consequence of augmented drug distribution via the release of accumulated intracellular drug from the infiltrating phagocytic cells and fibroblasts associated with abscess formation.

Abscess↗
PubMed1993

The comparative activity of azithromycin, macrolides and amoxycillin against streptococci in experimental infections.

Since serious sequelae may follow streptococcal infections, eradication is viewed as necessary for successful therapy. Studies were therefore conducted to compare the effectiveness of azithromycin with other macrolide antibiotics and amoxycillin to eliminate these organisms in experimental localized infections. In a Streptococcus pneumoniae lung infection induced by transtracheal challenge, the pathogen was not recovered after therapy with azithromycin (ED50 7.9 mg/kg), while clarithromycin was not effective (ED50 > 100 mg/kg). However, in a S. pneumoniae middle ear infection, azithromycin and clarithromycin were effective (ED50 2.9 and 6.3 mg/kg, respectively) in eradicating the pathogen from this closed space infection. Against a localized Streptococcus pyogenes infection (implanted inoculated disc), azithromycin effectively eradicated the pathogen, while clarithromycin, roxithromycin and erythromycin did not. Eradication of a viridans streptococcus or Streptococcus gordonii (formerly Streptococcus sanguis) from heart tissue in experimental bacterial endocarditis was also evaluated. Azithromycin given prophylactically or therapeutically was efficacious in eliminating the viridans streptococcus and S. gordonii in the bacterial endocarditis model of infection; erythromycin was only marginally effective in the same studies. All studies provided evidence of the bactericidal action of azithromycin in vivo and demonstrated the ability of the compound to eradicate streptococcal pathogens in localized infections.

Amoxicillin↗
PubMed1993

Comparison of the pharmacokinetics of three-day and five-day regimens of azithromycin in plasma and urine.

In an open crossover study, the pharmacokinetics of three-day and five-day regimens of azithromycin were compared. Fourteen healthy volunteers received oral doses of azithromycin once-daily, over three days (500 mg/day) and over five days (500 mg on day 1, followed by 250 mg/day on days 2-5). Plasma and urine concentrations were determined by HPLC. Azithromycin was found to be absorbed rapidly on the first and the last days of both regimens, with mean Tmax ranging between 2.5-3 h. On day 1, peak plasma concentrations were 0.37 mg/L and 0.31 mg/L, respectively, with three- and five-day regimens, and increased to 0.42 mg/L on the last day of the three-day regimen, but decreased to 0.18 mg/L at the end of the five-day regimen. Similarly, the AUC0-24 increased from 1.30 to 1.88 h.mg/L during the three-day regimen, and decreased from 1.24 to 0.80 h.mg/L on the five-day regimen. After absorption, azithromycin was distributed rapidly; the respective half-lives were 2.4 h and 2.2 h with the three-day and five-day regimens. Thereafter, a polyphasic decline of plasma concentrations was observed; the average half-lives between 8-48 h after administration were 27.9 h (three-day regimen) and 35.8 h (five-day regimen). In urine, 5.5% (three-day regimen) and 4.6% (five-day regimen) of the total dose was found as unchanged azithromycin over a 12-day period. The observed pharmacokinetics of azithromycin with both regimens conformed with the known pharmacokinetic behaviour of the drug. The treatment-related differences seen in the plasma concentrations were as expected from the different dosage schedules.

Administration, Oral↗
PubMed1994

Evaluation of the efficacy of prolonged administration of azithromycin in a murine model of chronic toxoplasmosis.

The efficacy of prolonged administration of azithromycin was evaluated in a murine model of lethal chronic toxoplasmosis. Mice were challenged intraperitoneally with cysts of a moderately virulent strain of Toxoplasma gondii, observed for 4 weeks and then allocated to the treatment or control group. All 26 animals given azithromycin 100 mg/kg/day for 100 days were protected compared with 19 of 25 control animals which died (P < 0.001). Nineteen of the 20 mice in the treatment group survived for an additional month while receiving the same azithromycin regimen but viable cysts were identified in the brain tissue of these animals when they were killed. Although there was no significant difference between the groups in terms of the number of cysts in the brain, the administration of azithromycin was associated with a reduction in brain inflammation. The concentrations of azithromycin in the brains of five animals ranged from 0.7 to 2.3 micrograms/g; there was no evidence of accumulation even after 100 doses. Azithromycin merits further evaluation as primary or secondary prophylaxis against toxoplasma encephalitis in individuals at risk of developing this complication.

Animals↗
PubMed1994

Pharmacokinetics of azithromycin and erythromycin in human endometrial epithelial cells and in cells infected with Chlamydia trachomatis.

The pharmacokinetics of azithromycin and erythromycin were examined in uninfected and Chlamydia trachomatis infected human endometrial epithelial cells in vitro. Cells which were grown in a polarized orientation showed a three-fold higher quantity of azithromycin uptake than did non-polarized cells. Cellular penetration profiles of azithromycin exceeded erythromycin by as much as eight-fold. In addition, approximately 20% of azithromycin remained cell-associated after 24 h in drug-free medium whereas erythromycin was not retained beyond 3 h. Hormone-responsive primary human endometrial gland epithelial cells, cultured directly after hysterectomy, showed enhanced uptake of both antimicrobials compared with laboratory adapted epithelial cell lines. Cells infected with a genital serovariant of C. trachomatis showed no significant difference in antibiotic uptake during the early stages of the chlamydial developmental cycle, and only a slight decrease in azithromycin uptake in the late stage of infection compared with non-infected cells. Morphological evidence of the bactericidal activity of azithromycin was evident in infected cells at most stages of the chlamydial developmental cycle, whereas the same concentration of erythromycin produced less evidence of marked bactericidal activity as observed by transmission electron microscopy.

Azithromycin↗
PubMed1995

Azithromycin induces in vitro a time-dependent increase in the intracellular killing of Staphylococcus aureus by human polymorphonuclear leucocytes without damaging phagocytes.

Despite its clinical efficacy on intracellular pathogens, the in-vitro intracellular antimicrobial activity of azithromycin, has been shown to be absent or lower than expected from the intracellular concentrations reached. To test the possibility that the high intracellular concentrations of the drug could damage phagocytes, the present study evaluated the effects of azithromycin on (a) the intracellular killing of Staphylococcus aureus by human blood neutrophils (PMNs) and (b) the viability and the respiratory burst of PMNs. Using a fluorochrome assay, we assessed the phagocytosis and intracellular killing of S. aureus by PMNs preloaded with azithromycin, or by PMNs unloaded but with the drug in the culture medium. In addition, possible drug-induced damage to PMNs was evaluated measuring: (a) hydrogen peroxide (H2O2) production and (b) the percentages of PMNs dead at the end of the phagocytosis process. Compared to control PMNs without drug, a time-dependent enhancement in the intracellular killing was observed which was statistically significant after 60 min incubation. The increased intracellular killing was higher in suspensions of unloaded PMNs and azithromycin (P < 0.01) that in suspensions of preloaded PMNs (P < 0.05). This increased intracellular killing was not associated with increased proportions of dead phagocytes, either in preloaded or unloaded PMNs (P < 0.05, each comparison). Similarly no changes in the production of H2O2 by PMNs were observed in the presence of azithromycin. Thus, azithromycin induces a time-dependent increase in the bactericidal activity of human PMNs, without increasing the phagocyte self-killing or modifying H2O2 production.

Adolescent↗
PubMed1996

Azithromycin--review of key chemical, pharmacokinetic and microbiological features.

One of the chemical features that distinguishes the 15-membered ring azalide azithromycin from the 14-membered ring macrolide compound erythromycin is the former's increased stability at acid pH. Azithromycin also differs pharmacokinetically from erythromycin, an important feature being azithromycin's ability to achieve high tissue concentrations, with the agent being delivered to the sites of infection by direct uptake and by targeted delivery via phagocytes. High tissue concentrations are maintained for prolonged periods because of azithromycin's long half-life, leading to once-daily dosing for 3 or 5 days. Notable microbiological features of azithromycin are in-vitro activity against many pyogenic bacteria (e.g. Neisseria gonorrhoeae and Moraxella catarrhalis), as well as organisms against which beta-lactam antibiotics are usually ineffective (e.g. Legionella and Chlamydia spp.), organisms that are resistant to benzylpenicillin and erythromycin (e.g. Haemophilus influenzae) and organisms for which satisfactory therapy is limited (e.g. Toxoplasma gondii and the Mycobacterium avium-intracellulare complex). These properties of azithromycin suggest that it might be a useful agent for the treatment of a wide range of bacterial infections.

Animals↗
PubMed1996

A randomized, comparative study to evaluate the efficacy and tolerability of a 3-day course of azithromycin versus a 10-day course of co-amoxiclav as treatment of adult patients with lower respiratory tract infections.

Clinical and bacteriological efficacy and tolerability of azithromycin (500 mg once daily for 3 days) and those of a 10-day regimen of co-amoxiclav (37 mg three times daily) were evaluated in a large-scale, double-blind comparative study of 369 patients (> or = 18 years old) with acute lower respiratory tract infections. After treatment, 165/173 (95%) azithromycin- and 166/173 (96%) co-amoxiclav-treated patients had responded satisfactorily (cure or improvement). Baseline pathogens (mainly Streptococcus pneumoniae and Haemophilus influenzae) were eradicated in 82/82 (100%) azithromycin- and 73/74 (99%) co-amoxiclav-treated patients who were bacteriologically assessable. Adverse events, which were predominantly of mild to moderate severity and mostly affected the gastrointestinal system, were recorded in 13/186 (7%) azithromycin- and 19/183 (10%) co-amoxiclav-treated patients. Only two (1%) azithromycin-treated patients discontinued treatment due to adverse events compared with eight (4%) who received co-amoxiclav. The results show that azithromycin at a dose of 500 mg once daily for 3 days is an effective and safe alternative to a 10-day, three-times-daily course of co-amoxiclav in the treatment of lower respiratory tract infections in adults.

Adolescent↗
PubMed1996

Efficacy, safety and tolerability of azithromycin versus roxithromycin in the treatment of acute lower respiratory tract infections.

In an open, multicentre study, the clinical and bacteriological efficacy, safety and tolerance of azithromycin and roxithromycin were compared in a total of 204 adults with acute lower respiratory tract infections (LRTIs) [acute bronchitis, acute infectious exacerbations of chronic bronchitis (AIECBs), or pneumonia]. Following treatment with 500 mg/day azithromycin administered orally once daily for 3 days, a satisfactory clinical response of cure or improvement was recorded in 91/99 (91.9%) evaluable patients at the post-therapy evaluation (day 10-14). Of the 94 evaluable patients treated with roxithromycin (150 mg given orally twice daily for 10 days), 82 (87.2%) were classified as cured or improved at post-therapy. The main pathogens isolated before treatment were Staphylococcus aureus, Streptococcus pneumoniae, Streptococcus species, Haemophilus influenzae and Moraxella catarrhalis. In the 46 azithromycin-treated patients evaluated both clinically and bacteriologically, 92.0% of pathogens were eradicated; H. influenzae persisted in one azithromycin-treated patient with acute bronchitis who was classed as clinically improved. In the roxithromycin group, 81.1% of the pathogens were eradicated in 35 patients; S. aureus persisted in one clinically cured patient with acute bronchitis, and H. influenzae persisted in one patient with AIECB and one with pneumonia, and Haemophilus species in one with AIECB, who were all classified as clinically improved. Azithromycin was well tolerated with a lower incidence of adverse events than that recorded in the roxithromycin treatment group. Treatment was not discontinued due to adverse events in any of the azithromycin-treated patients, whereas two roxithromycin-treated patients were withdrawn from treatment due to vomiting and/or dyspepsia.

Acute Disease↗
PubMed1996

Paediatric safety of azithromycin: worldwide experience.

Adverse events and laboratory abnormalities were monitored over 35 days after the commencement of treatment in 45 open studies conducted in Europe, South America, Africa and Asia. These studies were to assess the clinical efficacies of azithromycin and comparator antimicrobial agents in the treatment of paediatric acute bacterial infections. Children (6 months-16 years of age) had been treated with an oral suspension of azithromycin (10 mg/kg given once daily for 3 consecutive days) or with the approved oral dosing regimen of the comparator (amoxycillin, co-amoxiclav, cefixime, cefaclor, clarithromycin, erythromycin, penicillin V, cloxacillin, or roxithromycin). Adverse events were recorded in 232/2655 (8.7%) children treated with azithromycin and in 180/1844 (9.8%) who received comparator treatment. The majority of the treatment-related adverse events were classed as being of only mild or moderate severity and were gastrointestinal: 140 (5.3%) in azithromycin- and 120 (6.5%) in comparator-treated children. Co-amoxiclav was responsible for proportionately more of such events than any other agent. Treatment was discontinued prematurely due to an adverse event in 34 (1.3%) azithromycin- and in 31 (1.7%) comparator-treated children. Incidences of clinically significant laboratory abnormalities were low and occurred with comparable frequency in both treatment groups. The present analysis confirms that azithromycin can be safely used to treat bacterial infections in children of all ages.

Adolescent↗
PubMed1999

Treatment of typhoid fever with azithromycin versus chloramphenicol in a randomized multicentre trial in India.

To compare the clinical and bacteriological efficacies of azithromycin and chloramphenicol for treatment of typhoid fever, 77 bacteriologically evaluable adults, with blood cultures positive for Salmonella typhi or Salmonella paratyphi A susceptible to their assigned drugs, were entered into a randomized open trial at four hospitals in India. Forty-two patients were randomized to receive azithromycin 500 mg p.o. od for 7 days and 35 to receive chloramphenicol 2-3 g p.o. od in four divided doses for 14 days. Thirty-seven patients (88%) in the azithromycin group responded with clinical cure or improvement within 8 days and 30 patients (86%) in the chloramphenicol group responded with cure or improvement. By day 14 after the start of treatment, all patients treated with azithromycin and all except two of the patients treated with chloramphenicol (94%) were cured or improved. Blood cultures repeated on day 8 after start of therapy showed eradication of organisms in 100% of patients in the azithromycin group and 94% of patients in the chloramphenicol group. By day 14 the eradication rate in the chloramphenicol group had increased to 97%. Stool cultures on days 21 and 35 after start of treatment showed no prolonged faecal carriage of Salmonella spp. in either group. These results indicate that azithromycin given once daily for 7 days was effective therapy for typhoid fever in a region endemic with chloramphenicol-resistant S. typhi infection and was equivalent in effectiveness to chloramphenicol given to patients with chloramphenicol-susceptible infections.

Adolescent↗
PubMed2000

The effect of azithromycin on intracellular Legionella pneumophila in the Mono Mac 6 cell line at serum concentrations attainable in vivo.

We investigated the antimicrobial efficacy of clinically meaningful, low concentrations of azithromycin against intracellular growth of two clinical isolates of Legionella pneumophila. The mature monocytic cell line Mono Mac 6 was used as a model to investigate the effects of antimicrobial agents on L. pneumophila. Extracellular susceptibility was determined by microdilution susceptibility testing in BYEalpha broth after 48 h of incubation. Mono Mac 6 cells infected with L. pneumophila were incubated with various concentrations of azithromycin. After 2 days of incubation, intracellular bacteria were released from the phagocytes and plated on to BCYEalpha agar. Addition of the intracellular-acting antibiotics azithromycin or ciprofloxacin at their MICs (0.5 and 0. 015 mg/L, respectively) resulted in a significant decrease in cfu, of up to approximately 1 log(10) after 48 h of incubation. In contrast, incubation of intraphagocytic L. pneumophila in the presence of antibiotics without intracellular activity (ceftizoxime, imipenem or amoxycillin-clavulanic acid) did not have any effect. Azithromycin inhibited intracellular replication at concentrations as low as 0.125 mg/L, approximately one-quarter of the extracellular MIC. The Mono Mac 6 cell line is a useful infection model for investigating the intracellular activity of antimicrobial agents in vitro. In accordance with clinical data and animal experiments, azithromycin and ciprofloxacin inhibited the intraphagocytic replication of L. pneumophila. In particular, azithromycin killed ingested legionellae in vitro at concentrations below the peak serum concentrations and below the MIC.

Anti-Bacterial Agents↗
PubMed2001

Efficacy of azithromycin, clarithromycin and beta-lactam agents against experimentally induced bronchopneumonia caused by Haemophilus influenzae in mice.

Azithromycin is an azalide with potent activity against Haemophilus influenzae including ampicillin-resistant strains. We evaluated the efficacy of azithromycin, clarithromycin and three beta -lactams when used for 1 day only and for 3 days for the treatment of a murine model of bronchopneumonia, using three strains of H. influenzae, two of which were ampicillin resistant. MICs of azithromycin (1-2 mg/L) and clarithromycin (4-8 mg/L) were similar for the three strains. The MICs of cefdinir and cefcapene for beta-lactamase-negative ampicillin-resistant (BLNAR) H. influenzae were 32 times higher than those for beta-lactamase-positive ampicillin-resistant and ampicillin-susceptible strains. The viable counts in the infected tissues of azithromycin-treated mice with bronchopneumonia caused by the susceptible strain TUM8, beta-lactamase-positive strain TUH36 and BLNAR strain TUH267 were less than the counts obtained with the other antibiotics used, irrespective of MIC. At a dose of 50 mg/kg, the area under the concentration curve and the half-life of azithromycin in the lungs were respectively three times higher and six times longer than those of clarithromycin. Our results indicate that azithromycin may be useful for both ampicillin-susceptible and ampicillin-resistant bronchopneumonial infections caused by H. influenzae.

Animals↗
PubMed2003

Pharmacodynamic activity of azithromycin against macrolide-susceptible and -resistant Streptococcus pneumoniae simulating clinically achievable free serum, epithelial lining fluid and middle ear fluid concentrations.

BACKGROUND: The association between macrolide resistance mechanisms and bacteriological eradication of Streptococcus pneumoniae remains poorly studied. The present study, using an in vitro pharmacodynamic model, assessed azithromycin activity against macrolide-susceptible and -resistant S. pneumoniae simulating clinically achievable free serum (S), epithelial lining fluid (ELF) and middle ear fluid (MEF) concentrations. MATERIALS AND METHODS: Two macrolide-susceptible [PCR-negative for both mef(A) and erm(B)] and six macrolide-resistant [five mef(A)-positive/erm(B)-negative displaying various degrees of macrolide resistance and one mef(A)-negative/erm(B)-positive] S. pneumoniae were tested. Azithromycin was modelled simulating a dosage of 500 mg/250 mg by mouth, once a day [free S: maximum concentration (Cmax) 0.2 mg/L, t1/2 68 h; free ELF Cmax 1.0 mg/L, t1/2 68 h] and 10 mg/kg by mouth, once a day (free MEF: Cmax 1.0 mg/L, t1/2 68 h) using a one compartment model. Starting inocula were 1 x 10(6) cfu/mL in Mueller-Hinton broth with 2% lysed horse blood. Sampling at 0, 2, 4, 6, 12, 24 and 48 h assessed the extent of bacterial killing (decrease in log10 cfu/mL versus initial inoculum). RESULTS: Free azithromycin concentrations in serum, ELF and MEF simulating time above the MIC (T > MIC) of 100% [area under the curve to MIC (AUC0-24/MIC] > or = 36.7] were bactericidal (> or = 3 log10 killing) at 24 and 48 h versus macrolide-susceptible S. pneumoniae. Against macrolide-resistant S. pneumoniae, free serum concentrations providing T > MIC of 0% or AUC0-24/MIC < or = 1.1 demonstrated no bacterial inhibition followed by regrowth at 24 and 48 h, whereas free ELF and MEF providing T > MIC of 0% or AUC0-24/MIC of 4.6 produced a bacteriostatic (0.2-0.5 log10 killing at 24 h) effect with a mef(A) strain with an azithromycin MIC of 2 mg/L. Against mef(A)-positive S. pneumoniae strains with azithromycin MICs > or = 4 mg/L, no bacterial killing occurred at any time point and rapid regrowth was observed simulating ELF or MEF T > MIC of 0% or AUC0-24/MIC < or = 2.3. CONCLUSION: Azithromycin serum, ELF and MEF concentrations rapidly eradicated macrolide-susceptible S. pneumoniae but did not eradicate macrolide-resistant S. pneumoniae regardless of resistance phenotype.

Anti-Bacterial Agents↗
PubMed2006

Macrolide resistance of Staphylococcus aureus and Haemophilus species associated with long-term azithromycin use in cystic fibrosis.

OBJECTIVES: Azithromycin is used to modulate exuberant inflammatory response in patients with cystic fibrosis (CF). The purpose of this study was to determine the association between long-term use of azithromycin in CF patients and change over time in macrolide susceptibility of Staphylococcus aureus and Haemophilus spp. METHODS: The study was performed at the Erasmus MC-Sophia Children's Hospital. CF patients' sputum cultures were obtained at routine visits and at pulmonary exacerbations. All cultures between January 1999 and March 2004 were included. Antibiotic susceptibility of S. aureus and Haemophilus spp. was tested routinely. Susceptibility was compared with isolates from sputum of non-CF patients. Logistic regression was used to analyse the association between azithromycin use and resistance, adjusting for age, Pseudomonas carriage and time-trends. RESULTS: In March 2004 one-third of CF patients were on azithromycin maintenance treatment. S. aureus (715 isolates) and/or Haemophilus (537 isolates) were cultured in 141 of the 155 patients on one or more occasions. The study period was divided into octiles. Erythromycin resistance in S. aureus increased from 6.9 to 53.8% and clarithromycin resistance in Haemophilus spp. from 3.7 to 37.5%. Resistance but also isolation rates were strongly related to azithromycin use. Resistance of 3217 S. aureus control isolates remained stable and resistance of 3257 Haemophilus controls increased, although at a slower rate than CF isolates. CONCLUSIONS: Over a 4 year period, azithromycin maintenance therapy in our CF population was associated with an increase in macrolide resistance in S. aureus and Haemophilus spp.

Adolescent↗
PubMed2006

Effect of timing and duration of azithromycin therapy of leptospirosis in a hamster model.

OBJECTIVES: Azithromycin is not associated with significant adverse effects or restricted usage in certain populations unlike standard antileptospirosis agents. In this study, the utility of short courses of azithromycin in treating or preventing leptospirosis was investigated in a lethal hamster model. METHODS: All hamsters were infected intraperitoneally with 10(5) leptospires. In experiment one, animals received 5 mg/kg of doxycycline or 10 mg/kg of azithromycin via intraperitoneal injection beginning on the second day after infection and continuing once daily for 1, 2, 3 or 5 days. In experiment two, animals received 1 or 2 day courses of azithromycin initiated 2 or 4 days following infection, or 4 days prior to infection. RESULTS: All untreated control animals died between the sixth and ninth day following infection. In experiment one, survival rates in the doxycycline groups were 0, 50, 80 and 100% for those animals treated for 1, 2, 3 and 5 days, respectively. Except for the 1 day treatment group (which had an 80% survival), there was 100% survival in all azithromycin-treated groups. In experiment two, all animals treated after infection survived until study completion. No animals survived with 1 day of therapy started 4 days prior to infection while only 20% survived if they received 2 days. CONCLUSIONS: These results suggest short-course therapy with azithromycin, even started well after infection, is efficacious in preventing mortality from acute leptospirosis.

Animals↗
PubMed2004

High prevalence of Chlamydia pneumoniae infection in cyclosporin A-induced post-transplant gingival overgrowth tissue and evidence for the possibility of persistent infection despite short-term treatment with azithromycin.

BACKGROUND: Cyclosporin A (CsA) induces gingival overgrowth (GO) in up to a quarter of CsA-treated renal transplant recipients. A short-term therapy with azithromycin effectively reduces GO, indicating a possible involvement of microorganisms in the pathogenesis of CsA-induced GO. We aimed to determine if there could be any relationship between infection with Chlamydia pneumoniae and GO pathogenesis. In addition, we determined the long-term persistence rate of C. pneumoniae infection in residual GO tissue when azithromycin treatment failed to eliminate GO. METHODS: Chlamydia pneumoniae IgG and IgM antibody titres were measured by microimmunofluorescence technique in sera of kidney recipients with (n = 11) and without (n = 89) GO. GOs were rated and gingivectomies were performed before treatment with 500 mg of azithromycin for 3 days and at months 6 and 12 post-treatment when C. pneumoniae titres were re-evaluated. Nested polymerase chain reaction was performed to identify C. pneumoniae-specific DNA in GO tissues. Results of C. pneumoniae antibody titres from patients with GO were compared with pair-matched controls without GO. RESULTS: Chlamydia pneumoniae IgM titres were elevated in five of 11 patients with GO and in none without GO, whereas the difference of C. pneumoniae IgG titres between patients with GO and pair-matched controls did not reach significance (P<0.57). Chlamydia pneumoniae-specific DNA was found in 10 of 11 GO tissue samples pre-treatment. Azithromycin therapy effectively reduced GO and C. pneumoniae IgM titres. In residual GO, C. pneumoniae-specific DNA remained detectable after 1 year in all GO tissue samples despite azithromycin treatment. The C.pneumoniae IgM titres correlated with GO scores. CONCLUSION: Chlamydia pneumoniae infection is highly prevalent in CsA-induced GO. The infection can persist over a long period in residual GO despite short-term azithromycin therapy. The results indicate that CsA immunosuppression enhances C. pneumoniae infection rates in non-cardiovascular tissue.

Adult↗