In-vitro activity of gatifloxacin against Chlamydia trachomatis and Chlamydia pneumoniae

Patricia M. Roblin and Margaret R. Hammerschlag*

Division of Infectious Diseases, Department of Pediatrics, State University of New York, Health Science Center at Brooklyn, Brooklyn, New York 11203, USA


    Abstract
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 Abstract
 Introduction
 Materials and methods
 Results and discussion
 References
 
We compared the activity of gatifloxacin, a new quinolone, ofloxacin and erythromycin against five isolates of Chlamydia trachomatis and 20 isolates of Chlamydia pneumoniae, including TW183 and clinical isolates from the USA and Japan. Testing was done in cycloheximide-treated HEp-2 cells. Gatifloxacin was slightly less active against C. trachomatis and slightly more active against C. pneumoniae than ofloxacin, with MICs at which 90% of the isolates had no inclusions and minimal chlamydicidal concentrations at which 90% of the isolates had no inclusions after passage of 0.25 mg/L. Gatifloxacin was less active than erythromycin for both species.


    Introduction
 Top
 Abstract
 Introduction
 Materials and methods
 Results and discussion
 References
 
Chlamydiaspp. are important human pathogens. Chlamydia trachomatis is the most frequent sexually transmitted infection in the United States, responsible for over three million cases of cervicitis and urethritis per year.1 Chlamydia pneumoniae is a frequent cause of community-acquired respiratory tract infection including pneumonia and bronchitis in adults and children.2,3 Quinolones have attracted interest as potential therapy for both sexually transmitted infections and community-acquired respiratory tract infections because they are active against a wide range of pathogens responsible for these diseases. Ofloxacin is currently recommended by the Centers for Disease Control as an alternative regimen for the treatment of genital C. trachomatis infections in adults.1 We previously reported that several quinolones, including ofloxacin, levofloxacin, grepafloxcin, sparfloxacin, trovafloxacin and moxifloxacin have significant activity against C. pneumoniae in vitro. 4 ,5 ,6 ,7 We tested a new 8-methoxyquinolone, gatifloxacin, for activity against C. trachomatisand C. pneumoniae in comparison with ofloxacin and erythromycin.


    Materials and methods
 Top
 Abstract
 Introduction
 Materials and methods
 Results and discussion
 References
 
Gatifloxacin (Bristol Myers Squibb, Wallingford, CT, USA), ofloxacin (Ortho Pharmaceuticals, Raritan, NJ, USA) and erythromycin were supplied as powders and solubilized according to instructions from the manufacturers. Five strains of C. trachomatis were tested, E Bour (ATCC VR-3483), F IC-CAL-3 (ATCC VR-346), H UW-43/CX, (ATCC VR-879), J UW-36/CX (ATCC VR-885) and L2434Bu (ATCC VR-902B). All were obtained from the ATCC. Twenty strains of C. pneumoniae were tested: TW-183 and AR39 (Washington Research Foundation, Seattle, WA, USA), 10 clinical isolates from Brooklyn, T2023 (ATCC VR1356), T2043 (ATCC VR1355), T2337, T2219, BAL14, BAL15, BAL16, BAL37, BAL48, BAL62, a clinical isolate from Japan, J-21 (ATCC VR1435), CDC8 from Atlanta, W6805 from Wisconsin and five isolates from a multicentre pneumonia treatment study (379CBD, 327JM, 40DEF, 473GET, 284JL).

Susceptibility testing of C. trachomatis and C. pneumoniae was performed in cell culture using HEp-2 cells grown in 96-well microtiter plates.7 Each well was inoculated with 0.1 mL of the test strain diluted to yield 103 to 104 inclusion-forming units (IFU) per mL, centrifuged at 1700g for 1 h and incubated at 35°C for 1 h. Wells were then aspirated and overlaid with 0.2 mL of medium containing 1 mg/L of cycloheximide and serial two-fold dilutions of the test drug. After incubation at 35°C for 72 h, cultures were fixed and stained for inclusions with fluorescein-conjugated anti-body to the lipopolysaccharide genus antigen (Pathfinder, Kallestad Diagnostics, Chaska, MN, USA). The MIC was the lowest antibiotic concentration at which no inclusions were seen. The minimal bactericidal concentration (MBC) was determined by aspirating the antibiotic-containing medium, washing wells twice with phosphate buffered saline and adding antibiotic-free medium. Cultures were frozen at –70°C, thawed, passed on to new cells, incubated for 72 h then fixed and stained as above. The MBC was the lowest antibiotic concentration which resulted in no inclusions after passage. All tests were run in triplicate.


    Results and discussion
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 Abstract
 Introduction
 Materials and methods
 Results and discussion
 References
 
The MICs and MBCs for all five strains of C. trachomatiswere 0.25 mg/L of gatifloxacin, 0.125 mg/L of ofloxacin and 0.03 mg/L of erythromycin. The MICs and MBCs for C. pneumoniae are given in the Table. Gatifloxacin was slightly less active against C. trachomatis, and slightly more active against C. pneumoniae than ofloxacin but less active than erythromycin against both species


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Table. Activity of gatifloxacin and other agents against 20 isolates of C. pneumoniae
 
The MICs of gatifloxacin against C. pneumoniae were very consistent from strain to strain, especially in view of the wide geographic distribution of the isolates tested. Data on the activity of gatifloxacin against Chlamydia spp. are limited. Miyashita et al.8 tested gatifloxacin against three strains of C. trachomatis,five strains of C. pneumoniae, including TW 183 and AR 39 and two strains of Chlamydia psittaci. The MICs for all three species ranged from 0.063 to 0.125 mg/L. The MICs for C. pneumoniae TW 183 and AR39 were 0.063 mg/L, which is four-fold more active than our results with these strains. This difference may be within the standard error of the test. They also tested 25 recent clinical isolates and the MIC90 and MBC90 were 0.125 mg/L, which is not significantly different from our results with American clinical isolates. The MIC90 and MBC90 of ofloxacin against C. pneumoniae were 0.5 and 1 mg/L, respectively, which are almost exactly the values we found (MIC90 and MBC90 0.5 mg/L). Miyashita et al.8 also evaluated the efficacy of treatment with gatifloxacin and other antibiotics on survival in a mouse model of C. psittaci pneumonia. The survival of mice treated with 5 mg/kg of gatifloxacin was significantly higher than that seen with ofloxacin. Wise et al.9 tested gatifloxacin against three strains of C. trachomatis and C. pneumoniaeTW-183. The MICs and MBCs ranged from 0.06 to 0.12 mg/L, which was two- to four-fold more active than we found for C. trachomatis and TW-183.

The 1998 Guidelines for the Treatment of Sexually Transmitted Diseases lists ofloxacin as an alternative regimen for the treatment of uncomplicated genital C. trachomatis infection in adolescents and adults.1 Ofloxacin is similar in efficacy to doxycycline and azithromycin, but is more expensive and offers no advantage with regard to dosing and the length of treatment.1 Based on its in-vitro activity and pharmacokinetics10, gatifloxacin should have equivalent efficacy to ofloxacin for treatment of C. trachomatis infections.

There are no published studies that have assessed the efficacy of any quinolone for the treatment of C. pneumoniae infection that have utilized culture.4,5 The diagnosis was based on serology alone, thus microbiological efficacy could not be assessed. We treated three patients with culture documented C. pneumoniae infection (bronchitis and pneumonia) with grepafloxacin. Although grepafloxacin has an MIC90 and MBC90 of 0.5 mg/L against C. pneumoniae,two of three patients remained culture-positive and symptomatic despite 2 weeks of treatment with the drug.7 Prospective studies of gatifloxacin for the treatment of genital chlamydia infections and community-acquired pneumonia utilizing culture of C. trachomatis and C. pneumoniae will determine the role of gatifloxacin in the treatment of these infections.


    Notes
 
* Correspondence address. Department of Pediatrics, Box 49, SUNY Health Science Center at Brooklyn, 450 Clarkson Avenue, Brooklyn, NY 11203-2098, USA. Tel: +1-718-245-4075; Fax: +1-718-245-2118; E-mail: mhammerschlag{at}pol.net Back


    References
 Top
 Abstract
 Introduction
 Materials and methods
 Results and discussion
 References
 
1 . CDC. (1998). 1998 Guidelines for the treatment of sexually transmitted diseases. Centers for Disease Control. Morbidity and Mortality Weekly Report 47, RR-1, 1–111..[Medline]

2 . Block, S., Hedrick, J., Hammerschlag, M. R., Cassell, G. H. & Craft, J. C. (1995). Mycoplasma pneumoniae and Chlamydia pneumoniae in pediatric community-acquired pneumonia: comparative efficacy and safety of clarithromycin versus erythromycin ethylsuccinate. Pediatric Infectious Diseases Journal 14, 471–7.[ISI][Medline]

3 . Grayston, J. T., Campbell, L. A., Kuo, C.-C., Mordhorst, C. H., Saikku, P., Thom, D. H. et al. (1990). A new respiratory tract pathogen: Chlamydia pneumoniae strain TWAR. Journal of Infectious Diseases 161, 618–25.[ISI][Medline]

4 . Hammerschlag, M. R., Hyman, C. L. & Roblin, P. M. (1992). In vitro activities of five quinolones against Chlamydia pneumoniae. Antimicrobial Agents and Chemotherapy 36, 682–3.[Abstract]

5 . Hammerschlag, M. R. (1994). Antimicrobial susceptibility and therapy of infections due to Chlamydia pneumoniae. Antimicrobial Agents and Chemotherapy 38, 1873–8.[ISI][Medline]

6 . Hammerschlag, M. R. (1999). Activity of quinolones against Chlamydia pneumoniae. Drugs, in press.

7 . Roblin, P. M., Montalban, G. & Hammerschlag, M. R. (1994). In vitro activities of OPC-17116, a new quinolone; ofloxacin; and sparfloxacin against Chlamydia pneumoniae. Antimicrobial Agents and Chemotherapy 38, 1402–3.[Abstract]

8 . Miyashita, N., Niki, Y., Kishimoto, T., Nakajima, M. & Matsushima, T. (1997). In vitro and in vivo activities of AM-1155, a new fluoroquinolone, against Chlamydia spp. Antimicrobial Agents and Chemotherapy 41, 1331–4.[Abstract]

9 . Wise, R., Brenwald, N. P., Andrews, J. M. & Boswell, F. (1997). The activity of the methylpiperazinyl fluoroquinolone CG 5501: a comparison with other fluoroquinolones. Journal of Antimicrobial Chemotherapy 39, 447–52.[Abstract]

10 . Nakashima, M., Uematsu, T., Kosuge, K., Kusajima, H., Ooie, T., Masuda, Y. et al. (1995). Single- and multiple-dose pharmacokinetics of AM-1155, a new 6-fluoro-8-methoxy quinolone, in humans. Antimicrobial Agents and Chemotherapy 39, 2635 –40.[Abstract]

Received 11 October 1998; returned 22 February 1999; revised 18 March 1999; accepted 23 May 1999