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[Studies on susceptibility of isolated organisms from pediatric infections against various antimicrobial agents]
R Fujii1, T Shinozaki, H Meguro
1Department of Pediatrics, School of Medicine, Teikyo University.
Insights
This study evaluated twelve oral antimicrobial agents against pediatric infection pathogens. Rokitamycin and quinolones showed broad-spectrum activity, but resistance is emerging for some agents.
Area of Science:
- Microbiology
- Pharmacology
- Infectious Diseases
Background:
- Pediatric infections pose a significant health challenge.
- Understanding antimicrobial resistance patterns is crucial for effective treatment.
- Evaluating novel and existing antimicrobial agents is essential for combating bacterial pathogens.
Purpose of the Study:
- To assess the in vitro antimicrobial activity of twelve oral agents against common pediatric pathogens.
- To investigate the susceptibility of Streptococcus pyogenes to macrolides and tetracyclines in relation to T-antigen types.
- To identify effective antimicrobial agents for treating pediatric infections caused by various bacteria.
Main Methods:
- In vitro susceptibility testing of twelve oral antimicrobial agents.
- Minimum Inhibitory Concentration (MIC) determination for various bacterial species.
- Antimicrobial activity evaluation against Staphylococcus aureus, Streptococcus pyogenes, Streptococcus pneumoniae, Branhamella catarrhalis, Haemophilus influenzae, Campylobacter spp., Mycoplasma pneumoniae, and Chlamydia trachomatis.
Main Results:
- Rokitamycin (RKM), josamycin, ofloxacin, and minocycline demonstrated strong activity against Staphylococcus aureus.
- Streptococcus pyogenes showed high resistance to tetracyclines (TCs), particularly certain T-antigen types, while remaining susceptible to beta-lactams and RKM.
- Quinolones exhibited excellent activity against Branhamella catarrhalis and Haemophilus influenzae, though increasing resistance was noted for quinolones.
- Macrolide antibiotics (MLs) and quinolones were highly effective against Campylobacter spp., with no observed resistance.
- Beta-lactams and MLs showed good activity against Streptococcus pneumoniae, but many strains were resistant to TCs.
Conclusions:
- Rokitamycin and quinolones are promising agents for pediatric infections due to their broad-spectrum activity.
- High rates of tetracycline resistance in Streptococcus pyogenes and Streptococcus pneumoniae necessitate alternative treatment strategies.
- Emerging resistance to quinolones warrants continued monitoring and judicious use.
- Macrolide antibiotics remain effective against certain pathogens like Campylobacter spp. and may be useful against Mycoplasma pneumoniae and Chlamydia trachomatis.
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)