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The importance of macrolide-resistant (MR) Mycoplasma pneumoniae has become much more apparent in the past decade. We investigated differences in the therapeutic efficacies of macrolides, minocycline, and tosufloxacin against MR M. pneumoniae. A total of 188 children with M. pneumoniae pneumonia confirmed by culture and PCR were analyzed. Of these, 150 patients had a strain with an MR gene and 134 had one with an A-to-G mutation at position 2063 of M. pneumoniae 23S rRNA domain V. Azithromycin (n ‫؍‬ 27), clarithromycin (n ‫؍‬ 23), tosufloxacin (n ‫؍‬ 62), or minocycline (n ‫؍‬ 38) was used for definitive treatment of patients with MR M. pneumoniae. Defervescence within 48 h after the initiation of antibiotic therapy was observed in 41% of the patients in the azithromycin group, 48% of those in the clarithromycin group, 69% of those in the tosufloxacin group, and 87% of those in the minocycline group. The average number of days of fever after the administration of antibiotic treatment was lower in the minocycline and tosufloxacin groups than in the macrolide groups. The decrease in the M. pneumoniae burden, as estimated by the number of DNA copies, after 48 to 96 h of treatment was more rapid in patients receiving minocycline (P ‫؍‬ 0.016) than in those receiving tosufloxacin (P ‫؍‬ 0.049), azithromycin (P ‫؍‬ 0.273), or clarithromycin (P ‫؍‬ 0.107). We found that the clinical and bacteriological efficacies of macrolides against MR M. pneumoniae pneumonia was low. Our results indicated that minocycline rather than tosufloxacin can be considered the first-choice drug for the treatment of M. pneumoniae pneumonia in children aged >8 years.

We conducted nationwide surveillance to investigate regional differences in macrolide-resistant (MR) Mycoplasma pneumoniae strains in Japan. The prevalence of MR M. pneumoniae in pediatric patients gradually increased between 2008 and 2012. Although regional differences were observed, high levels of MR genes were detected in all seven surveillance areas throughout Japan and ranged in prevalence from 50% to 93%. These regional differences were closely related to the previous administration of macrolides.

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The microbiological and clinical efficacies of macrolides for treating patients with MR M. pneumoniae pneumonia were low. These results show that macrolides are clearly less effective in patients with MR M. pneumoniae pneumonia.

We evaluated isolates obtained from children with Mycoplasma pneumoniae infection throughout Japan during 2008–2015. The highest prevalence of macrolide-resistant M. pneumoniae was 81.6% in 2012, followed by 59.3% in 2014 and 43.6% in 2015. The prevalence of macrolide-resistant M. pneumoniae among children in Japan has decreased.

We investigated differences in the clinical findings between 30 patients with macrolide-resistant Mycoplasma pneumoniae pneumonia and 43 patients with macrolide-sensitive M. pneumoniae pneumonia in adolescents and adults. No differences in clinical presentation were observed between the two groups. Among patients with macrolide-resistant Mycoplasma pneumoniae pneumonia, treatment was more effective in the groups that received quinolones and minocycline than in the group that received macrolides (P ‫؍‬ 0.0361 and P ‫؍‬ 0.0237, respectively). Mycoplasma pneumoniae is a major cause of community-acquired pneumonia (CAP) in school-age children and young adults (1, 2). A specific diagnosis of M. pneumoniae infection is important because treatment with routinely used ␤-lactam antibiotics is ineffective against these organisms because they lack a cell wall. Thus, the Japanese Respiratory Society (JRS) CAP guidelines have been recommended as a rapid and simple scoring system based on clinical and laboratory findings for the presumptive diagnosis of M. pneumoniae pneumonia (1,3,4). Our recent study demonstrated that the JRS scoring system was the most useful tool for initiating the administration of adequate antibiotic therapy for probable M. pneumoniae pneumonia among the rapid diagnostic methods tested (5).Although M. pneumoniae pneumonia is usually mild in severity, macrolide-resistant (MR) M. pneumoniae with mutations in the 23S rRNA gene has emerged in pediatric patients with CAP (6, 7). More than 60% of M. pneumoniae strains in pediatric patients showed high resistance to 14-and 15-membered ring macrolides with a MIC of Ն64 mg/liter (8-10). The clinical and bacteriological efficacy of macrolides for treating cases of MR M. pneumoniae pneumonia was lower than that in cases of macrolide-sensitive (MS) M. pneumoniae pneumonia in pediatric patients (9-13). In contrast to pediatric patients, the available data on MR M. pneumoniae infection in adolescent and adult patients are limited (8,14). The purpose of the present study was to identify a means of rapidly distinguishing MR M. pneumoniae pneumonia from MS M. pneumoniae pneumonia in daily clinical practice without waiting for genetic analysis results. We compared the underlying conditions, pneumonia severity, clinical symptoms, laboratory data, prognostic factors, and radiographic findings between patients with MR M. pneumoniae pneumonia and those with MS M. pneumoniae pneumonia (MR patients and MS patients, respectively) in adolescents and adults. Based on the clinical presentation, we evaluated the usefulness of rapid and simple clinical diagnostic methods (5), the JRS scoring system (1, 3, 4), and high-resolution computed tomography (HRCT) (15, 16) for the early presumptive diagnosis of M. pneumoniae pneumonia. An additional purpose of this study was to investigate the drug susceptibility of MR isolates and differences in therapeutic efficacy against MR M. pneumoniae among macrolides, quinolones, and minocycline.Adolescent and adult patients with CAP who visited 12 i...

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