title: [Studies on susceptibility of isolated organisms from pediatric infections against various antimicrobial agents].
abstract: Twelve oral antimicrobial agents were tested for their antimicrobial activities against causative organisms isolated from pediatric infections. Activities of these antimicrobial agents against Streptococcus pyogenes were also examined in relation to T-antigen typing of the species. The results of the investigation are summarized as follows. 1. Against Staphylococcus aureus, rokitamycin (RKM), josamycin, ofloxacin, minocycline exhibited strong antimicrobial activities, and few strains of S. aureus showed resistance to these antimicrobial agents. More strains exhibited resistance to erythromycin (EM) than to other macrolide antibiotics (MLs) examined. Amoxicillin (AMPC)-resistance was often observed also. 2. Against S. pyogenes, beta-lactam antibiotics (beta-lactams) and RKM had MIC80 of 0.20 microgram/ml or below, and no resistant strains of this organism were observed against these antibiotics. Only 2 resistant strains (2.0%) of S. pyogenes to MLs were detected, but resistance to tetracyclines (TCs) was observed at a high frequency, with 71.4% or more strains among T-4, T-6, T-12 and T-28 antigen types exhibited resistance to TCs. Among the 21 strains of T-12 antigen type examined, only one strain (4.8%) was found resistant to MLs. These observations suggested that the reduction in the frequency of ML-resistant strains was not due to the reduction in the number of T-12 antigen type strains but due to losses of resistance factors against MLs of plasmids. 3. Antibacterial activities of beta-lactams and MLs against Streptococcus pneumoniae strains were good, similarly to activities against S. pyogenes. But many strains of S. pneumoniae were resistant to TCs. 4. New quinolone antimicrobial agents (quinolones) showed excellent activities against Branhamella catarrhalis strains with EM and RKM showing the next best activities. The number of resistant strains against quinolones, however, seemed to be on an increase. 5. Quinolones had strong antimicrobial activities against Haemophilus influenzae, few strains of which showed resistance to quinolones. AMPC had the next best activity, but approximately 10% of H. influenzae exhibited resistance to this antibiotic. 6. Against Campylobacter spp., quinolones and MLs showed the best activities with MIC80 values at or below 0.25 microgram/ml, and no resistant strains of the species against these antimicrobial agents were observed. Fosfomycin and TCs showed somewhat inferior activities to quinolones and MLs, with beta-lactams showing still lower activities. 7. Only few strains of Mycoplasma pneumoniae and Chlamydia trachomatis were examined, but MLs and TCs appeared to be effective against these organisms.(ABSTRACT TRUNCATED AT 400 WORDS)
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002648:Child; D004352:Drug Resistance, Microbial; D004917:Erythromycin / Q000494:pharmacology; D006193:Haemophilus influenzae / Q000187:drug effects; D006801:Humans; D007933:Leucomycins / Q000494:pharmacology*; D015644:Miocamycin / Q000031:analogs & derivatives*; D012141:Respiratory Tract Infections / Q000382:microbiology; D013211:Staphylococcus aureus / Q000187:drug effects*; D013297:Streptococcus pyogenes / Q000187:drug effects*
chemical_list: D000900:Anti-Bacterial Agents; D007933:Leucomycins; D015644:Miocamycin; D004917:Erythromycin; C033383:rokitamycin