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Clinical and microbiologic consequences of amikacin use during a 42-month period
Abstract:
In June 1980, 23% of our Pseudomonas aeruginosa isolates and 53% of our Serratia species were resistant to gentamicin and tobramycin. During a 3 1/2-year period of almost exclusive amikacin usage, we noted a fall in overall resistance of gram-negative organisms to tobramycin and gentamicin from 18.8% and 19.3% to 15.2% and 16.2%, respectively. This fall in resistance was most notable for Escherichia coli, Proteus mirabilis, and Serratia species. During this period there was no increase in amikacin resistance. Age, hospitalization, prior antibiotic therapy, and Foley catheter use were predisposing factors in acquiring amikacin-resistant organisms. Amikacin-resistant gram-negative bacilli were usually sensitive to newer penicillins or cephalosporins.
Insights
Exclusive amikacin use reduced resistance to gentamicin and tobramycin in gram-negative organisms. Amikacin resistance did not increase, and resistant strains remained susceptible to newer antibiotics.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Antimicrobial Resistance
Background:
- High rates of gentamicin and tobramycin resistance in Pseudomonas aeruginosa and Serratia species were observed in June 1980.
- Aminoglycoside antibiotics are crucial for treating serious gram-negative bacterial infections.
Purpose of the Study:
- To evaluate the impact of prolonged, exclusive amikacin usage on the resistance patterns of gram-negative bacteria.
- To identify risk factors associated with acquiring amikacin-resistant gram-negative organisms.
- To determine the susceptibility of amikacin-resistant strains to alternative antibiotic classes.
Main Methods:
- Retrospective analysis of antimicrobial susceptibility data over a 3 1/2-year period.
- Monitoring of resistance trends for gentamicin, tobramycin, and amikacin in gram-negative isolates.
- Identification of predisposing factors for amikacin-resistant organism acquisition.
Main Results:
- Overall resistance to gentamicin and tobramycin decreased significantly during the amikacin-focused period.
- Specific reductions in resistance were noted for Escherichia coli, Proteus mirabilis, and Serratia species.
- No increase in amikacin resistance was observed; age, hospitalization, prior antibiotics, and Foley catheter use were risk factors for amikacin resistance.
Conclusions:
- Exclusive amikacin use can lead to a decrease in resistance to other aminoglycosides like gentamicin and tobramycin.
- Amikacin-resistant gram-negative bacilli typically remain susceptible to newer beta-lactam antibiotics (penicillins and cephalosporins).
- Vigilant monitoring and strategic antibiotic selection are essential for managing antimicrobial resistance.