Trimethoprim-resistant Enterobacteriaceae in urinary tract infection

Area of Science:

• Microbiology
• Antimicrobial Resistance
• Pharmacology

Background:

• The introduction of trimethoprim-sulfamethoxazole (TMP-SMX) in 1973 aimed to combat bacterial infections.
• Monitoring antimicrobial resistance is crucial for effective treatment strategies.

Purpose of the Study:

• To assess the incidence of trimethoprim-resistant Enterobacteriaceae following the introduction of TMP-SMX.
• To evaluate the correlation between TMP-SMX therapy and resistance patterns.

Main Methods:

• Minimum inhibitory concentration (MIC) was used to determine trimethoprim resistance levels.
• In vitro susceptibility testing was performed for trimethoprim and sulfonamide.
• Patient data on previous TMP-SMX therapy was analyzed.

Main Results:

• No increase in trimethoprim-resistant Enterobacteriaceae was observed since 1973.
• MIC values for trimethoprim resistance ranged from 1.6 to 800 µg/ml, with most isolates between 1.6 and 12.5 µg/ml.
• A significant correlation exists between prior TMP-SMX therapy and high-level trimethoprim resistance.

Conclusions:

• The clinical use of TMP-SMX has not led to an increased incidence of trimethoprim-resistant Enterobacteriaceae.
• While some resistant organisms remain susceptible to the combination, high-level resistance may indicate treatment failure.
• Previous TMP-SMX exposure is linked to higher levels of trimethoprim resistance.