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[Antibacterial activities of various aminoglycosides against clinically isolated methicillin-resistant Staphylococcus
Abstract:
Methicillin-resistant Staphylococcus aureus (MRSA) were isolated from samples collected from various patients during 1986, and antibacterial activities of 6 aminoglycosides (AGs) (netilmicin (NTL), gentamicin (GM), sisomicin (SISO), dibekacin (DKB), tobramycin (TOB) and amikacin (AMK] and 4 beta-lactam antibiotics (cefazolin (CEZ), cefmetazole (CMZ), cloxacillin (MCIPC) and methicillin (DMPPC) against these MRSA were evaluated. Among these 6 AGs, NTL was the most potent, and its MIC50 and MIC80 were 1.56 and 3.13 micrograms/ml, respectively. Antibacterial activities of GM, SISO, DKB and TOB were weak, and MIC50's of GM and DKB were both 100 micrograms/ml, while those of SISO and TOB were 50 and greater than 100 micrograms/ml, respectively. Frequency of highly resistant specimens to AMK was rather low and its MIC50 and MIC80 were 12.5 and 25 micrograms/ml, respectively. As for antibacterial activities of the above 4 beta-lactam antibiotics, the MIC50 and MIC80 of CMZ were 6.25 and 12.5 micrograms/ml, respectively, and therefore, its antibacterial activity to MRSA is relatively good. However, MIC50's of CEZ, MCIPC and DMPPC were all greater than 100 micrograms/ml, showing poor antibacterial activities. Recently, MRSA became a problem in various fields of clinical practice, and a number of literatures reporting refractory infections caused by MRSA have been published. Since MRSA is featured as multiply resistant bacteria, it is known that MRSA is resistant to the majority of existing antibiotics (penicillins, cephems, macrolides, AGs, etc.). In 1985, we reported results of our study concerning the antibacterial activities of a number of CEPs and some of AGs against multiply resistant S. aureus including MRSA.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Netilmicin demonstrated potent activity against Methicillin-resistant Staphylococcus aureus (MRSA). Cefmetazole showed good antibacterial activity, while other beta-lactams were less effective against MRSA isolates.
Area of Science:
- Microbiology
- Infectious Diseases
- Pharmacology
Context:
- Methicillin-resistant Staphylococcus aureus (MRSA) poses a significant clinical challenge due to its multi-drug resistance.
- Evaluating antibiotic efficacy against prevalent MRSA strains is crucial for effective treatment strategies.
Purpose:
- To assess the in vitro antibacterial activity of selected aminoglycosides and beta-lactam antibiotics against MRSA isolates.
- To identify antibiotics with potent activity for potential use in treating MRSA infections.
Summary:
- Netilmicin (NTL) exhibited the strongest activity among the tested aminoglycosides (AGs) against MRSA, with MIC50 and MIC80 values of 1.56 and 3.13 µg/ml, respectively.
- Cefmetazole (CMZ) displayed relatively good antibacterial activity against MRSA (MIC50: 6.25 µg/ml, MIC80: 12.5 µg/ml).
- Other tested AGs (gentamicin, sisomicin, dibekacin, tobramycin) and beta-lactams (cefazolin, cloxacillin, methicillin) showed weak to poor activity against the MRSA isolates.
Impact:
- This study highlights netilmicin and cefmetazole as potentially valuable agents for combating MRSA infections.
- Findings contribute to understanding antibiotic resistance patterns in MRSA and inform clinical decision-making.
- Provides data on antibiotic susceptibility crucial for managing refractory MRSA infections.