Prevalence of MDR and XDR in UPEC
The prevalence of multidrug-resistant (MDR) UPEC ranges from 7-97% depending on geographic region and patient population, with the most recent large-scale U.S. data showing 12% MDR prevalence, while extensively drug-resistant (XDR) UPEC remains relatively uncommon at approximately 5%.
Geographic and Temporal Variation in MDR Prevalence
United States Data
- In the most recent large U.S. study (2016-2021), MDR UPEC prevalence was 12% among outpatient uncomplicated UTIs, showing a slight decrease from 13% over the study period 1
- Historical U.S. data from 2000 showed 7.1% MDR prevalence among urinary E. coli isolates, indicating the problem has worsened over two decades 2
- Resistance to 1,2,3, and 4 antibiotic classes was found in 19%, 18%, 8%, and 4% of isolates respectively, with 1% resistant to ≥5 classes 1
International Data Shows Higher Rates
- Iran reported dramatically higher MDR rates of 61-68% (outpatients vs inpatients respectively) in 2012-2013 3
- Nepal demonstrated 64.9% MDR prevalence among pediatric UPEC isolates, representing one of the highest reported rates 4
XDR Prevalence
- XDR UPEC (extensively drug-resistant) was documented at 5% prevalence in pediatric patients in Nepal, representing the only study providing specific XDR data 4
- XDR remains less common than MDR but represents the most concerning resistance pattern clinically 4
Patient Demographics and Risk Factors
Age-Related Patterns
- Patients >65 years show higher MDR rates (8.7%) compared to those 18-65 years (6.1%) and ≤17 years (6.8%) 2
- Pediatric populations in resource-limited settings show particularly high MDR rates (64.9%) 4
Gender Differences
- Males demonstrate significantly higher MDR rates (10.4%) compared to females (6.6%) 2
Healthcare Setting
- Inpatients show modestly higher MDR rates (7.6%) versus outpatients (6.9%) 2
- Virtual and in-person care settings show similar resistance patterns, with no significant difference in MDR prevalence 1
ESBL Production and MDR Correlation
- Among ESBL-producing UPEC, 96.3% were MDR, demonstrating the strong association between ESBL production and multidrug resistance 5
- ESBL prevalence ranges from 34.6-38.9% among UPEC isolates 5, 4
- The most common ESBL gene is blaCTX-M (100% of ESBL-producers), followed by blaSHV (63%) and blaTEM (11.1%) 5
Common Resistance Patterns
Most Frequent MDR Phenotype
- The predominant MDR phenotype (57.9%) includes resistance to ampicillin, cephalothin, and trimethoprim-sulfamethoxazole 2
- Co-resistance to penicillins and trimethoprim-sulfamethoxazole occurs in 12% of isolates 1
- MDR involving penicillins, TMP-SMX, plus ≥1 additional antibiotic class occurs in 10% of cases 1
Antibiotic-Specific Resistance in MDR Isolates
- Among MDR UPEC: 97.8% resistant to ampicillin, 92.8% to trimethoprim-sulfamethoxazole, 86.6% to cephalothin, 38.8% to ciprofloxacin, and 7.7% to nitrofurantoin 2
- Resistance rates >50% were documented for ampicillin, ceftazidime, nalidixic acid, and trimethoprim-sulfamethoxazole in some regions 3
Regional Variation Within the United States
- U.S. regional MDR rates range from 4.3% (West North Central) to 9.2% (West South Central), demonstrating significant geographic heterogeneity 2
Critical Clinical Caveat
The definition of MDR varies across studies (resistance to ≥3 drug classes), making direct comparisons challenging, but the trend toward increasing resistance is consistent globally 3, 1, 4, 2. Local antibiogram data should guide empiric therapy decisions given the substantial geographic variation in resistance patterns.