Current mechanisms of resistance to antimicrobial agents in microorganisms causing infection in the patient at risk for infection
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Abstract:
The mechanisms of resistance encountered in bacteria causing infection in the patient at risk for infection are diverse. Most resistance currently seen is the result of plasmid transfer rather than mutational events. However, extensive use of antimicrobial agents in the hospital has caused the selection of organisms resistant to many agents by virtue of chromosomally mediated mechanisms. Staphylococcus aureus resistant to beta-lactams due to altered penicillin-binding proteins has become a problem in certain patients such as narcotic addicts and chronic care facility patients exposed to many beta-lactam antibiotics. S. epidermidis has also proved to be a problem in patients with indwelling foreign devices, and altered penicillin-binding proteins also make these organisms resistant to available penicillins and cephalosporins. Streptococcus fecalis has become increasingly resistant to aminoglycosides, erythromycin, and tetracyclines due to plasmid-mediated enzymes. Hemophilus influenzae resistant to both penicillins and chloramphenicol by virtue of beta-lactamases and chloramphenicol transacetylase has been encountered. Beta-lactamase-mediated resistance of Enterobacteriaceae, Escherichia coli, and Klebsiella pneumoniae to beta-lactam antibiotics has increased, and resistance of Serratia marcescens and Pseudomonas aeruginosa to aminoglycosides and penicillins is a widespread phenomenon. Mechanisms to reduce resistance will include not only careful attention to hygienic practices but also more appropriate use of antibiotics selecting the proper agent depending on the type of patient and environment in which the infection develops.
Insights
Bacterial resistance mechanisms are diverse, often involving plasmid transfer or chromosomal changes. Appropriate antibiotic use and hygiene are key to reducing antimicrobial resistance in hospitals.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Antimicrobial Resistance
Background:
- Bacterial infections in at-risk patients present diverse resistance mechanisms.
- Plasmid transfer is a primary driver of current resistance, alongside mutational events.
- Extensive hospital antimicrobial use selects for chromosomally mediated resistance.
Purpose of the Study:
- To review the diverse mechanisms of bacterial resistance.
- To highlight specific resistant organisms and their associated resistance mechanisms.
- To discuss strategies for reducing antimicrobial resistance.
Main Methods:
- Literature review of bacterial resistance mechanisms.
- Analysis of resistance patterns in common hospital-acquired pathogens.
- Discussion of clinical implications and control strategies.
Main Results:
- Staphylococcus aureus and S. epidermidis exhibit resistance to beta-lactams via altered penicillin-binding proteins.
- Streptococcus fecalis shows resistance to multiple antibiotics due to plasmid-mediated enzymes.
- Beta-lactamase production confers resistance in Enterobacteriaceae, E. coli, K. pneumoniae, H. influenzae, S. marcescens, and P. aeruginosa.
Conclusions:
- Diverse plasmid- and chromosome-mediated mechanisms contribute to bacterial resistance.
- Specific pathogens like S. aureus, S. epidermidis, S. fecalis, H. influenzae, and Enterobacteriaceae demonstrate significant resistance.
- Reducing resistance requires improved hygiene and judicious antibiotic selection tailored to patient and environmental factors.