Mycoplasma pneumoniae was made highly resistant to erythromycin in vitro by serial subculture in broth media containing erythromycin. The resistance developed to erythromycin was 200 Ag/ml with the Mac strain, a prototype of M. pneumoniae, and 10 ,g/ml with the Fukumura strain, an isolate. The erythromycin resistance was accompanied by cross resistance to other macrolide antibiotics (leucomycin, josamycin, spiramycin, and oleandomycin) and to lincomycin, but there was no resistance to vernamycin B. Resistance to the antibiotics developed in vitro or in vivo was stable after the microorganisms were repeatedly transferred in antibiotic-free media.Only a few studies have been reported on the development of antibiotic resistance in Mycoplasma pneumoniae. We first reported a case of M. pneumoniae pneumonia in which M. pneumoniae acquired high resistance to erythromycin, other macrolide antibiotics, and lincomycin during the administration of erythromycin (15). Masuda (14) reported decreased susceptibility to streptomycin in M. pneumoniae after four subcultures in media containing streptomycin.We have succeeded in making M. pneumoniae highly resistant to erythromycin with cross resistance to other macrolide antibiotics and lincomycin by serial subcultures in broth media containing erythromycin. The resistance developed was stable after the microorganisms were repeatedly subcultured in antibiotic-free media.MATERIALS AND METHODS Media. The broth medium for propagation of the microorganisms consisted of seven parts 2.1% pleuropneumonia-like organism (PPLO) broth (Difco), two parts unheated horse serum, one part 25% yeast extract, 1% glucose, 500 U of penicillin G per ml, 500Ag of thallium acetate per ml, and 0.002% phenol red according to the formula of Chanock et al. (4). In broth media used for antibiotic susceptibility tests, penicillin was omitted and the pH was adjusted to 7.8 before addition of the antibiotics. Agar media were prepared by replacing PPLO broth with 3.4% PPLO agar (Difco) in the above formula for propagation.Strains of M. pneumoniae. The strains used were
Primary lung cancer is rare in childhood. An asymptomatic 15-year-old boy was found to have a solitary circular shadow by a mass chest photofluorographic survey. The clinical course strongly suggested malignant tumor. Lobectomy three months after the detection of the shadow showed squamous cell carcinoma. At present, 3\m=1/2\years after surgery, the patient is healthy and attending school. Cases of primary lung cancer in childhood are reviewed.While the frequency of primary carcinoma of the lung has re¬ cently increased remarkably in adults, it is rare in childhood. Here we report a case of lung cancer (squamous cell carcinoma) found in a 15-year-old boy by a mass chest photofluorographic survey.The patient, a boy 15 years and 7 months of age, was a pupil of the third grade in middle school. No history of familial dis¬ ease, including malignancy, was obtained. He had enjoyed good health. He had never smoked, and his environment had not been unusual.From a mass survey for the detection of pulmonary tuberculosis on Jan 21, 1969, a photofluorogram of the chest showed ab¬ normal findings. Six days after the survey photofluoro¬ gram, at which time he had no complaints, a roentgenogram showed a solitary circu¬ lar shadow of homogeneous density 2.5 cm
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