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The emerging threat of multidrug-resistant gram-negative organisms in long-term care facilities
Erin O'Fallon1, Aurora Pop-Vicas, Erika D'Agata
1Department of Medicine, Hebrew Rehabilitation Center for Aged, Boston, MA 02131, USA. erinofallon@hrca.harvard.edu
Background:
Infections caused by antimicrobial-resistant bacteria are associated with substantial morbidity and mortality. Residents of long-term care facilities (LTCF) are among the main reservoirs of antimicrobial-resistant bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). Multidrug-resistant gram-negative organisms (MDRGN) are emerging as important pathogens among LTCF residents. Data on the clinical epidemiology of MDRGN, especially in comparison to VRE and MRSA, are limited.
Methods:
All clinical cultures collected from residents of a 750-bed LTCF for a period of 2 years were analyzed for the presence of MDRGN, VRE, and MRSA. Multidrug resistance among gram-negative bacteria was defined as resistance to three or more antimicrobials or antimicrobial groups including extended-spectrum penicillins (ampicillin/sulbactam or piperacillin/tazobactam), cephalosporins (cefazolin or ceftriaxone), gentamicin, ciprofloxacin, and trimethoprim-sulfamethoxazole (TMP/SMX).
Results:
A total of 1,661 clinical cultures were included in the analysis. MDRGN were recovered from 180 (10.8%) cultures, MRSA from 104 (6.3%), and VRE from 11 (0.6%). MDRGN were isolated more frequently than MRSA or VRE throughout the study period. The prevalence of MDRGN increased significantly from 7% in 2003 to 13% in 2005 (p = .001). More than 80% of MDRGN isolates were resistant to ciprofloxacin, TMP/SMX, and ampicillin/sulbactam. Resistance to three, four, and five or more antimicrobials were identified among 122 (67.8%), 47 (26.1%), and 11 (6.1%) MDRGN isolates, respectively.
Conclusions:
Rates of MDRGN exceeded those of MRSA and VRE and increased throughout the study period. Resistance to multiple, commonly prescribed antimicrobials among MDRGN raises concerns about therapeutic options available to treat MDRGN infections among LTCF residents.
Insights
Multidrug-resistant gram-negative organisms (MDRGN) are increasingly prevalent in long-term care facilities, surpassing methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). This rise in MDRGN poses significant challenges for treatment options.
Area of Science:
- Infectious Diseases
- Epidemiology
- Microbiology
Background:
- Antimicrobial resistance (AMR) in bacteria causes significant morbidity and mortality.
- Long-term care facilities (LTCFs) are reservoirs for AMR bacteria, including MRSA and VRE.
- Multidrug-resistant gram-negative organisms (MDRGN) are emerging pathogens in LTCFs, with limited epidemiological data.
Purpose of the Study:
- To investigate the clinical epidemiology of MDRGN in LTCF residents.
- To compare the prevalence of MDRGN with MRSA and VRE.
- To assess trends in MDRGN prevalence and resistance patterns over time.
Main Methods:
- Analysis of 1,661 clinical cultures from LTCF residents over two years.
- Definition of multidrug resistance in gram-negative bacteria based on resistance to ≥3 antimicrobial classes.
- Identification and quantification of MDRGN, MRSA, and VRE isolates.
Main Results:
- MDRGN were recovered from 10.8% of cultures, MRSA from 6.3%, and VRE from 0.6%.
- MDRGN prevalence increased significantly from 7% to 13% between 2003 and 2005.
- Over 80% of MDRGN isolates showed resistance to ciprofloxacin, TMP/SMX, and ampicillin/sulbactam.
Conclusions:
- MDRGN rates exceeded MRSA and VRE rates and showed an increasing trend in LTCFs.
- High levels of resistance to common antimicrobials among MDRGN limit therapeutic options.
- Urgent strategies are needed to address MDRGN infections in LTCF residents.
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