Antimicrob Agents Chemother. 1990 Dec;34(12):2445-8.
Antimicrobial interference with bacterial mechanisms of pathogenicity: effect of sub-MIC azithromycin [Zithromax] on gonococcal piliation and attachment to human epithelial cells.

Gorby GL, McGee ZA.

Section of Infectious Diseases, Omaha VA Medical Center, Nebraska.

The effects of subinhibitory concentrations of azithromycin [Zithromax] (CP-62,993) on the piliation and attachment properties of Neisseria gonorrhoeae were examined. Subinhibitory concentrations of azithromycin [Zithromax] significantly reduced the percentage of gonococci that expressed assembled pili on their surfaces by decreasing pilin subunit synthesis and substantially decreased gonococcal adherence to human mucosal cells.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1982402&dopt=Abstract Zithromax azithromycin




J Antimicrob Chemother. 1990 Jan;25 Suppl A:1-5.
In-vitro activity of azithromycin, erythromycin, ciprofloxacin and norfloxacin against Neisseria gonorrhoeae, Haemophilus ducreyi, and Chlamydia trachomatis.

Slaney L, Chubb H, Ronald A, Brunham R.

Department of Medical Microbiology, University of Manitoba, Winnipeg, Canada.

The minimum inhibitory concentrations (MICs) of azithromycin, erythromycin, ciprofloxacin and norfloxacin for 300 strains of Neisseria gonorrhoeae, 100 strains of Haemophilus ducreyi and six strains of Chlamydia trachomatis were determined. The two quinolones were more active against gonococcal strains than were the two macrolides. Azithromycin [Zithromax] was approximately eight-fold more active against N. gonorrhoeae than was erythromycin (MIC90: 0.25 mg/l azithromycin, 2.0 mg/l erythromycin). The Mtr phenotype of gonococci increased azithromycin [Zithromax] MICs approximately four fold. Azithromycin [Zithromax] was less active than erythromycin against C. trachomatis. Azithromycin [Zithromax] had considerable activity against H. ducreyi and was ten-fold more active than was erythromycin (MIC90: 0.004 mg/l azithromycin, 0.03 mg/l erythromycin). Clinical trials of azithromycin [Zithromax] in the treatment of chlamydial infection and genital ulcer disease are indicated.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2154426&dopt=Abstract Zithromax azithromycin




J Antimicrob Chemother. 1990 Jan;25 Suppl A:101-8.
Efficacy of azithromycin [Zithromax] in the treatment of guinea pigs infected with Legionella pneumophila by aerosol.

Fitzgeorge RB, Featherstone AS, Baskerville A.

Public Health Laboratory Service, Centre for Applied Microbiology and Research, Salisbury, Wiltshire, UK.

Azithromycin [Zithromax] and erythromycin were compared for efficacy in guinea pigs infected with an aerosol containing Legionella pneumophila. When administered intraperitoneally, azithromycin [Zithromax] was very effective in the treatment of experimental Legionnaires' disease. Even at the low dose of 3.6 mg/kg/day it gave 100% survival and eliminated lung infectivity two days following infection. In contrast, erythromycin at a much higher dose (96 mg/kg/day) gave only 83.3% survival and failed to eliminate organisms from the lung six days after infection. The histological findings confirmed the superiority of azithromycin. A single dose of azithromycin [Zithromax] given intraperitoneally at 3.6 or 14.4 mg/kg gave survival rates of 83.3 and 100%, respectively. Azithromycin [Zithromax] was also found to be superior to erythromycin in eliminating lung infectivity and reducing mortality, when administered orally. However, oral administration of azithromycin [Zithromax] was not as effective as intraperitoneal when assessed by lung histopathology, although it was still superior to oral erythromycin treatment.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2154427&dopt=Abstract Zithromax azithromycin




J Antimicrob Chemother. 1990 Jan;25 Suppl A:15-8.
In-vitro activity of azithromycin [Zithromax] against various Gram-negative bacilli and anaerobic bacteria.

Kitzis MD, Goldstein FW, Miegi M, Acar JF.

Hopital Saint Joseph, Paris, France.

The MICs of azithromycin, erythromycin and roxithromycin were determined (by an agar dilution method) for 65 strains of Gram-negative bacteria responsible for endocarditis and gastrointestinal infections, for 20 strains of non-fermenting Gram-negative bacteria and for 16 strains of anaerobic bacteria. The MICs of azithromycin [Zithromax] were up to eight times lower than those of erythromycin and (except in the case of Flavobacterium spp.) up to 16 times lower than those of roxithromycin. Azithromycin [Zithromax] was ineffective against strains showing a high degree of erythromycin resistance.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2154432&dopt=Abstract Zithromax azithromycin




J Antimicrob Chemother. 1990 Jan;25 Suppl A:19-24.
Comparative in-vitro activity of azithromycin [Zithromax] and erythromycin against Gram-positive cocci, Haemophilus influenzae and anaerobes.

Maskell JP, Sefton AM, Williams JD.

Department of Medical Microbiology, London Hospital Medical College, UK.

The in-vitro activities of azithromycin [Zithromax] and erythromycin were compared against 689 clinical isolates, including Gram-positive cocci, Haemophilus influenzae, and anaerobes. Of the 100 methicillin-susceptible isolates of Staphylococcus aureus tested, 77% were susceptible to 1 mg/l azithromycin [Zithromax] and 0.5 mg/l erythromycin, whereas 22% were resistant to 32 mg/l of both compounds. All methicillin-resistant S. aureus isolates were highly resistant to both macrolides (MIC greater than 64 mg/l). Coagulase-negative staphylococci showed a wide range of susceptibilities to both compounds; MIC50 values for azithromycin [Zithromax] and erythromycin for all isolates were 0.5 and 0.25 mg/l, respectively. With the exception of enterococci, both macrolides showed similar activity against streptococci; MIC90 values for both group A and group B streptococci were 0.03 and 0.06 mg/l for erythromycin and azithromycin, respectively. Azithromycin [Zithromax] was less active than erythromycin against enterococci, with mode MICs of 4.0 and 1.0 mg/l, respectively; about 20% of isolates were highly resistant to both compounds. Azithromycin [Zithromax] was substantially more active than erythromycin against H. influenzae; 41% of isolates were inhibited by 0.5 mg/l azithromycin [Zithromax] and all isolates were inhibited by 2 mg/l. The MIC90 for erythromycin was 8 mg/l; 36% of isolates required concentrations of greater than or equal to 4 mg/l for inhibition. The anaerobic bacteria tested showed similar susceptibility to both azithromycin [Zithromax] and erythromycin.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2154433&dopt=Abstract Zithromax azithromycin




J Antimicrob Chemother. 1990 Jan;25 Suppl A:25-8.
Bacteriostatic and bactericidal activity of azithromycin [Zithromax] against Haemophilus influenzae.

Goldstein FW, Emirian MF, Coutrot A, Acar JF.

Hopital Saint Joseph, Paris, France.

Macrolide antibiotics, commonly used in upper and lower respiratory tract infections, are inconsistently active against Haemophilus influenzae. The new azalide, azithromycin, was compared with erythromycin and roxithromycin against this pathogen. Azithromycin [Zithromax] (MIC range 0.06-1 mg/l) was four to eight times more potent than erythromycin (MIC range 0.5-8 mg/l) and roxithromycin (MIC range 0.5-16 mg/l). At 1 mg/l, 100% of the strains of H. influenzae were inhibited by azithromycin [Zithromax] compared with 16% with erythromycin and 5% with roxithromycin. Azithromycin [Zithromax] exhibited a rapid bactericidal effect, with a 99.9% kill at 4 h. The MBC was equal to or up to four-times greater than the MIC.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2154434&dopt=Abstract Zithromax azithromycin




J Antimicrob Chemother. 1990 Jan;25 Suppl A:29-31.
In-vitro activity of azithromycin [Zithromax] compared with other macrolides and oral antibiotics against Salmonella typhi.

Metchock B.

Grady Memorial Hospital, Atlanta, GA.

The in-vitro activity of azithromycin [Zithromax] against 60 clinical isolates of Salmonella typhi was determined by broth microdilution and compared with eight macrolides, including erythromycin, and with other orally administered antimicrobial agents (ampicillin, amoxycillin, cefaclor, trimethoprim/sulphamethoxazole, chloramphenicol, tetracycline, and ciprofloxacin). Azithromycin [Zithromax] was more potent (MIC range 4-16 mg/l; MIC90 8 mg/l) than erythromycin (MIC range 32- greater than 128 mg/l; MIC90 greater than 128 mg/l). Of the other macrolides, only rosaramicin showed increased activity against Salm. typhi (MIC range 16-32 mg/l; MIC90 32mg/l) when compared with erythromycin. All 60 Salm. typhi were susceptible to ciprofloxacin (MIC greater than 0.5 mg/l). In 22 isolates, resistance to one or more of the following compounds occurred: ampicillin, amoxycillin, cefaclor, tetracycline, chloramphenicol, trimethoprim/sulphamethoxazole.

Source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2154435&dopt=Abstract Zithromax azithromycin