In-vitro activity of grepafloxacin, a new fluoroquinolone, against mycoplasmas

Cécile M. Bébéara,*, Hélène Renaudina, Thierry Schaeverbekea, Françoise Leblancb and Christiane Bébéara

a Laboratoire de Bactériologie, Université Victor Segalen Bordeaux 2, 146 rue Léo Saignat, 33076 Bordeaux cedex; b GlaxoWellcome, 100 Route de Versailles, 78163 Marly le Roi, France


    Abstract
 Top
 Abstract
 Introduction
 Materials and methods
 Results and discussion
 References
 
The in-vitro activity of grepafloxacin, a new oral fluoroquinolone antibiotic, was compared with those of three other fluoroquinolones and two unrelated antimicrobials, doxycycline and erythromycin, against various Mycoplasma spp. For 65 mycoplasma and 42 ureaplasma strains, grepafloxacin (MIC range 0.03- 2 mg/L) was some two to 16 times more active than ofloxacin and ciprofloxacin, showing similar activity to that of sparfloxacin. MBCs of grepafloxacin increased two- to 16-fold when compared with MICs and were comparable to those of sparfloxacin, and lower than those of ofloxacin and ciprofloxacin.


    Introduction
 Top
 Abstract
 Introduction
 Materials and methods
 Results and discussion
 References
 
Grepafloxacin is a new C 5-methyl fluoroquinolone. It has increased antibacterial activity against Gram-positive bacteria, 1,2 and intracellular organisms such as Chlamydia and Legionella spp., 3 when compared with ciprofloxacin and ofloxacin. Grepafloxacin achieves high concentrations in tissue, especially in the lung. 4 The in-vitro activity of grepafloxacin was determined for clinical and reference stains of different human Mycoplasma spp., and compared with that of the fluoroquinolones, sparfloxacin, ofloxacin and ciprofloxacin, and also two unrelated antimicrobials, doxycycline and erythromycin.


    Materials and methods
 Top
 Abstract
 Introduction
 Materials and methods
 Results and discussion
 References
 
Antimicrobials

Each of the following antimicrobial agents was provided by the manufacturer: grepafloxacin (GlaxoWellcome, Marly le Roi, France); sparfloxacin (Rhône-Poulenc-Rorer, Vitry-sur-Seine, France); ofloxacin and erythromycin (Roussel-Uclaf, Paris, France); ciprofloxacin (Bayer-Pharma, Puteaux, France) and doxycycline (Pfizer, Orsay, France).

Susceptibility testing

MICs were determined as previously described, using an agar dilution method with Hayflick modified agar for mycoplasma strains, and a broth dilution method with Shepard medium for ureaplasma strains. 5 The final concentrations of antibiotics tested were 0.015- 32 mg/L. Minimal bactericidal concentrations (MBCs) of grepafloxacin and of the comparative compounds were determined as previously reported, for a reference strain of each species in test tubes, containing Shepard broth medium for Ureaplasma urealyticum and Hayflick modified broth medium for the other mycoplasma species. 6 The MBC was the lowest antibiotic concentration inhibiting a colour change in the broth culture, within 4-10 days (according to the species).

Strains

A total of 106 strains, including 32 strains of Mycoplasma pneumoniae (31 clinical respiratory isolates and one reference strain, FH), six strains of Mycoplasma genitalium (five clinical isolates and one reference strain, G37), nine strains of Mycoplasma fermentans (six clinical strains and three reference strains, PG18, K7 and incognitus), two strains of Mycoplasma penetrans (one urethral isolate and one reference strain, GTU-54), 16 strains of Mycoplasma hominis (15 clinical isolates and one reference strain, PG21), 21 U. urealyticum doxycycline-susceptible strains (20 clinical isolates and one reference strain, serotype 8), and 21 U. urealyticum doxycycline-resistant strains (20 clinical isolates and one reference strain, serotype 9) were studied. An additional group of eight fluoroquinolone-resistant mutants obtained from the reference strain M. hominis PG21 by stepwise selection on increasing concentrations of various fluoroquinolones was studied. 7


    Results and discussion
 Top
 Abstract
 Introduction
 Materials and methods
 Results and discussion
 References
 
Comparative in-vitro activities of grepafloxacin and other antimicrobials against all mycoplasma and ureaplasma strains, except M. hominis resistant mutants, are shown in the Table. The overall activity of grepafloxacin was very good against all strains tested. A concentration of 1 mg/L of grepafloxacin inhibited 90% of all strains, with the exception of the fluoroquinolone-resistant mutants of M. hominis PG21.


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Table. In-vitro activities of grepafloxacin and other antimicrobials against mycoplasmas
 
For M. pneumoniae and M. genitalium, MICs of grepafloxacin were comparable to those of sparfloxacin and doxycycline, but eight- to 16-fold lower than those of ofloxacin and ciprofloxacin. Erythromycin showed the best activity, inhibiting all M. pneumoniae and M. genitalium strains at a concentration <=0.015 mg/L. M. hominis and M. fermentans were highly susceptible to grepafloxacin (MIC 90 0.06 mg/L and MIC range 0.03-0.12 mg/L, respectively) and sparfloxacin (MIC 90 0.03 mg/L and <=0.015 mg/L, respectively). As expected, M. hominis and M. fermentans were resistant to erythromycin. Against M. penetrans, grepafloxacin was as active as sparfloxacin, but four- to eight-fold more active than ofloxacin and ciprofloxacin. The activity of grepafloxacin was also compared with that of sparfloxacin against the eight multistep fluoroquinolone-resistant mutants of the reference strain M. hominis PG21. A comparable increase in resistance to both antibiotics was found (MIC of grepafloxacin, 1- 4 mg/L; MIC of sparfloxacin, 0.06-4 mg/L). It is noteworthy that none of the eight mutants showed increased MICs of erythromycin or doxycycline when compared with those for PG21.

As noted previously, 8 U. urealyticum was slightly less susceptible to grepafloxacin than it was to sparfloxacin, but overall grepafloxacin was four-fold more active than ofloxacin and ciprofloxacin. Doxycycline-resistant strains were as susceptible to grepafloxacin and sparfloxacin as doxycycline-susceptible strains (as previously described for other fluoroquinolones). 6,8

For all Mycoplasma spp. (Table), the MBCs of grepafloxacin were two- to 16-fold higher than the MICs. MBCs of sparfloxacin were lower by one dilution, except for M. genitalium. Ofloxacin and ciprofloxacin exhibited higher MBCs for mycoplasma strains than grepafloxacin or sparfloxacin. It should be noted that sparfloxacin MBCs were two-fold lower than those of grepafloxacin for all mycoplasma strains except M. genitalium. For the doxycycline-susceptible and -resistant strains of U. urealyticum, MBCs of grepafloxacin and sparfloxacin were bactericidal at only one dilution lower than MIC. These results indicate that grepafloxacin, like sparfloxacin, is bactericidal in vitro for all mycoplasmas and ureaplasmas.

In summary, grepafloxacin, like sparfloxacin 9 and BAY-128039, 6 can be ranked among the most active fluoroquinolones tested against Mycoplasma and Ureaplasma spp.; this study extends significantly the results of previous studies. 3,8 Its reportedly high distribution in lung tissue 4 and demonstrated clinical efficacy in M. pneumoniae pneumonia 10 may ensure an important role for grepafloxacin in the treatment of respiratory infections caused by mycoplasma species.


    Acknowledgments
 
This study was supported in part by a grant from Glaxo Wellcome. Part of these studies was presented at the Thirty-Seventh Interscience Conference on Antimicrobial Agents and Chemotherapy, Toronto, October 1997.


    Notes
 
* Tel: +33-5-57-16-25; Fax: +33-5-56-79-60-42; E-mail: cecile.bebear{at}u-bordeaux2.fr Back


    References
 Top
 Abstract
 Introduction
 Materials and methods
 Results and discussion
 References
 
1 . Imada, T., Miyazaki, S., Nishida, M., Yamaguchi, K. & Goto, S. (1992). In vitro and in vivo antibacterial activities of a new quinolone, OPC-17116. Antimicrobial Agents and Chemotherapy 36, 573–9.[Abstract]

2 . Neu, H. C., Fang, W., Gu, J. W. & Chin, N. X. (1992). In vitro activity of OPC-17116. Antimicrobial Agents and Chemotherapy 36, 1310–5.[Abstract]

3 . Ridgway, G. L., Salman, H., Robbins, M. J., Dencer, C. & Felmingham, D. (1997). The in-vitro activity of grepafloxacin against Chlamydia spp., Mycoplasma spp., Ureaplasma urealyticum and Legionella spp. Journal of Antimicrobial Chemotherapy 40 , Suppl. A, 31–4.[Abstract/Free Full Text]

4 . Cook, P. J., Andrews, J. M., Wise, R., Honeybourne, D. & Moudgil, H. (1995). Concentrations of OPC-17116, a new fluoroquinolone antibacterial, in serum and lung compartments. Journal of Antimicrobial Chemotherapy 35, 317–26.

5 . Bébéar, C. & Robertson J. (1996). Determination of minimal inhibitory concentration. In Molecular and Diagnostic Procedures in Mycoplasmology, Volume II, Diagnostic Procedures (Tully, J. G. &. Razin, S., Eds), pp. 189–99. Academic Press.

6 . Bébéar, C. M., Renaudin, H., Boudjadja, A. & Bébéar, C. (1998). In vitro activity of BAY-128039, a new fluoroquinolone, against mycoplasmas. Antimicrobial Agents and Chemotherapy 42, 703–4.[Abstract/Free Full Text]

7 . Bébéar, C. M., Bové, J. M., Bébéar, C. & Renaudin, J. (1997). Characterization of Mycoplasma hominis mutations involved in resistance to fluoroquinolones. Antimicrobial Agents and Chemotherapy v,269 –73.

8 . Kenny, G. E. & Cartwright, F. D. (1993). Susceptibilities of Mycoplasma hominis, Mycoplasma pneumoniae, and Ureaplasma urealyticum to a new quinolone, OPC 17116. Antimicrobial Agents and Chemotherapy 36, 1726–7.

9 . Waites, K. B., Duffy, L. B., Schmid, T., Crabb, D., Pate, M. S. & Cassell, G. H. (1991). In vitro susceptibilities of Mycoplasma pneumoniae, Mycoplasma hominis, and Ureaplasma urealyticum, to sparfloxacin and PD 127391. Antimicrobial Agents and Chemotherapy 35, 1181–5.[ISI][Medline]

10 . Topkis, S., Swarz, H., Breisch, S. A. & Maroli, A. N. (1997). Efficacy and safety of grepafloxacin 600 mg daily for 10 days, in patients with community-acquired pneumonia. Clinical Therapeutics 19, 975–88.[ISI][Medline]

Received 4 September 1998; returned 23 November 1998; revised 21 December 1998; accepted 22 January 1999