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Emerging resistance in clinically important gram-positive cocci
1MRL Pharmaceutical Services, Franklin, TN 37064, USA.
Abstract:
In the first half of the decade of the 1990s, we in the United States have seen the emergence and escalation of substantial antimicrobial resistance in medically important gram-positive cocci. The incidence of methicillin resistance of Staphylococcus aureus continues to increase (now 18%), resulting in many more isolates that are multiply resistant; all S aureus isolates are still susceptible to vancomycin. Enterococci, particularly Enterococcus faecium, have increasingly developed resistance to penicillin, gentamicin, streptomycin, and vancomycin (the last plasmid-mediated). More than a fourth of Streptococcus pneumoniae strains are now resistant to penicillin, and these strains tend to be multiply resistant, including to cephalosporins and macrolides.
Insights
Antimicrobial resistance in gram-positive bacteria is rising in the US. Key pathogens like Staphylococcus aureus and Streptococcus pneumoniae show increasing resistance, posing significant public health challenges.
Area of Science:
- Microbiology
- Infectious Diseases
- Public Health
Background:
- The early 1990s witnessed a significant rise in antimicrobial resistance among key gram-positive cocci in the United States.
- This trend impacts medically important bacteria, necessitating urgent attention to treatment strategies and resistance monitoring.
Purpose of the Study:
- To document the escalating antimicrobial resistance patterns in prevalent gram-positive bacterial pathogens in the US during the early 1990s.
- To highlight the increasing incidence of multidrug-resistant strains.
Main Methods:
- Surveillance of antimicrobial susceptibility testing data for gram-positive cocci.
- Analysis of resistance trends for specific pathogens including Staphylococcus aureus, Enterococcus faecium, and Streptococcus pneumoniae.
Main Results:
- Methicillin resistance in Staphylococcus aureus increased to 18%, with a rise in multiply resistant isolates.
- Enterococcus faecium demonstrated increasing resistance to penicillin, gentamicin, streptomycin, and vancomycin, with plasmid-mediated vancomycin resistance noted.
- Over 25% of Streptococcus pneumoniae strains exhibited penicillin resistance, often accompanied by resistance to cephalosporins and macrolides.
Conclusions:
- The early 1990s marked a critical period of escalating antimicrobial resistance in common gram-positive pathogens in the US.
- The emergence of multidrug-resistant strains necessitates enhanced surveillance and the development of novel therapeutic approaches.