In vitro susceptibilities of Mycoplasma pneumoniae, Mycoplasma hominis, and Ureaplasma urealyticum to sparfloxacin and PD 127391

Abstract

The in vitro activities of two investigational quinolones, sparfloxacin (previously designated AT 4140) and PD 127391, were determined for 30 strains each of Mycoplasma pneumoniae, Mycoplasma hominis, and Ureaplasma urealyticum and compared with those of ciprofloxacin, tetracycline, clindamycin, and erythromycin. Erythromycin was the most active compound against M. pneumoniae (maximum MIC, <0.008 ,ug/ml). PD 127391 (MICs, <0.008 to 0.031 ,ug/ml), sparfloxacin (MICs, <0.008 to 0.25 pg/ml), clindamycin (MICs, <0.008 to 0.5 ,g/ml), and tetracycline (MICs, 0.063 to 0.25 pg/ml) were superior to ciprofloxacin (MICs, 0.5 to 2 ,ug/ml). Sparfloxacin and PD 127391 were active against M. hominis (MICs, <0.008 to 0.031 pg/ml for each) at concentrations comparable to those of clindamycin (MICs, <0.008 to 0.063 ,g/ml) and at concentrations lower than those of ciprofloxacin (MICs, 0.125 to 0.5 pg/ml). As expected, M. hominis was resistant to erythromycin (MICs, 32 to .256 ,ug/ml). For U. urealyticum, PD 127391 (MICs, 0.031 to 0.5 ,ug/ml) and sparfloxacin (MICs, 0.063 to 1 ,ug/ml) were superior to erythromycin (MICs, 0.25 to 4 ,g/ml), ciprofloxacin (MICs, 0.5 to 8 ,ug/ml), and clindamycin (MICs, 0.25 to 64 ,g/ml. Both new quinolones were equally active against tetracyclinesusceptible as well as -resistant strains of M. hominis and U. urealyticum. The possible influence of medium components and/or pH on MICs was evaluated by testing a Staphylococcus aureus reference strain with each antibiotic in SP-4 broth and 10-B broth and comparing the results with published MICs for this strain. MICs determined in 10-B broth for erythromycin were affected most. This study shows that the activities of sparfloxacin and PD 127391 are similar to one another and comparable or superior to those of other drugs used to treat mycoplasmal infections. The MICs of both new quinolones were consistently 2 to several dilutions lower than those of ciprofloxacin for each species.Mycoplasma pneumoniae has long been recognized as a common pulmonary pathogen, especially in younger age groups, causing as much as 20% of pneumonia in the general population and up to 50% in military settings (3). Most respiratory infections due to M. pneumoniae are self-limiting, but in some instances life-threatening disease may occur (3). Although naturally occurring strains of M. pneumoniae resistant to erythromycin have not been described to date, the effectiveness of this drug may be limited in some cases because of dose-related nausea, vomiting, or diarrhea, justifying the need for alternative treatment modalities (9). Knowledge of the antibiotic susceptibilities of Mycoplasma hominis and Ureaplasma urealyticum is of increasing importance because of the recognition of these organisms as opportunistic pathogens in newborn infants (4-6, 42, 45) and other immunosuppressed persons (36) and as primary pathogens in sexually transmitted diseases such as nongonococcal urethritis (5) and pelvic inflammatory disease (5). Resistance to traditional drugs such as tetracycline, which has ...

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“…The MIC end point was determined as the lowest concentration that showed significant or complete inhibition of inclusion-forming units. M. pneumoniae susceptibility was determined by the microbroth method of Waites et al (13). Serial 10-fold dilutions of each isolate were prepared in SP4 glucose broth (Remel) to determine the number of color changing units (CCU).…”

In Vitro Activity of Telithromycin (HMR3647), a New Ketolide, against Clinical Isolates of Mycoplasma pneumoniae in Japan

“…In vitro antimycoplasmal susceptibility tests have not been standardized; one was performed in this study by the broth microdilution method, which has been recently applied for several potent antibiotics for treatment of M. pneumoniae infections (6,8,9,12,14,15). M. pneumoniae isolates were grown to a concentration of 10 8 CFU/ml in modified Chanock broth medium (3) consisting of 7 parts pleuropneumonia-like organism (PPLO) broth without crystal violet (Difco Laboratories, Detroit, Mich.), 2 parts uninactivated horse serum, and 1 part a mixture of 25% fresh yeast extract, 1% glucose, and 0.002% phenol red adjusted to a pH of 7.8 with 1 N sodium hydroxide.…”

“…MIC 50 and MIC 90 were defined as the drug concentrations required to inhibit the growth of 50 and 90% of the total number of isolates tested, respectively (6,8,9,12,14,15). As a control for potential interactions between antibiotics, medium components, and pH, which could potentially affect the observed MICs, the American Type Culture Collection bacterial reference strain Staphylococcus aureus ATCC 29213 was inoculated into microtiter plates containing Chanock broth.…”

In vitro and in vivo activities of sparfloxacin against Mycoplasma pneumoniae

“…So, new chemotherapeutic drugs have been desired for the treatment of mycoplasmal infections. New quinolones (18) with a broad spectrum of activity against gram-positive and gram-negative bacteria have been developed during the past decade, and some of them have been reported to be active against M. pneumoniae (1, 2,8,12,17). In particular, the in vitro activity of sparfloxacin (10) against M. pneumoniae has been reported to be excellent (8).…”

“…So, new chemotherapeutic drugs have been desired for the treatment of mycoplasmal infections. New quinolones (18) with a broad spectrum of activity against gram-positive and gram-negative bacteria have been developed during the past decade, and some of them have been reported to be active against M. pneumoniae (1, 2,8,12,17). In particular, the in vitro activity of sparfloxacin (10) (17) with modified Chanock broth medium (4) consisting of 7 parts PPLO broth without crystal violet (Difco Laboratories, Detroit, Mich.), 2 parts uninactivated horse serum, 1 part 25% fresh yeast extract, 1% glucose, and 0.002% phenol red and adjusted to pH 7.8 and inocula of 105 CFU/ml.…”