Community-Acquired Uropathogenic Escherichia coli, Antimicrobial Susceptibility, and Extended-Spectrum Beta-Lactamase Detection

Abstract

INTRODUCTION Urinary tract infection is the second-leading reason for consults in primary health care. Bacterial urinary tract infections are the most common, of which Escherichia coli is the main etiologic agent. Antimicrobial resistance and multidrug resistance complicate eff ective community treatment, especially if resistance is caused by extendedspectrum beta-lactamase production. WHO recommends that antimicrobial susceptibility be evaluated in diff erent regions of the world at diff erent times. Community-acquired E. coli's susceptibility to colistin has not yet been studied in Cuba, and mcr-1 gene screening is necessary. OBJECTIVE Evaluate community-acquired uropathogenic E. coli isolates' susceptibility to antibiotics, including colistin, and identify extended-spectrum beta-lactamase-producing bacteria. METHODS We conducted a descriptive cross-sectional study that included 281 community-acquired uropathogenic E. coli isolates (153 from the Isle of Youth Special Municipality's Hygiene, Epidemiology, and Microbiology Center and 128 from Microbiology Laboratories of 7 institutions in Havana) from June 2016 through July 2018. We used the disk diff usion method to determine susceptibility to ampicillin, ampicillin/ sulbactam, cefazolin, trimethoprim/sulfamethoxazole, ciprofl oxacin, nitrofurantoin and fosfomycin. The disk elution method was used to determine susceptibility to colistin. The combined disk method was used to identify extendedspectrum beta-lactamases. Estimates were made regarding the frequency and percentages of antimicrobial susceptibility and resistance, as well as multidrug-resistance patterns. RESULTS Of the 281 isolates, 68.3% (192/281) were resistant to ampicillin, 54.8% (154/281) were resistant to ciprofl oxacin, and 49.5% (139/281) were resistant to trimethoprim/ sulfamethoxazole. Resistance to colistin was not detected. On the other hand, 14.2% (40/281) were susceptible to the 8 antibiotics we evaluated, 22.1% (62/281) showed resistance to only 1 antibiotic, and 63.7% (179/281) were resistant to 2 or more antibiotics. In the extended-spectrum beta-lactamase determination, 34.5% (97/281) had inhibition zones ≤14 mm with cefazolin. Of those with inhibition zones, 64.9% (63/97) were positive in the phenotype test, and 35.1% (34/97) were negative. In extended-spectrum beta-lactamase- producing bacteria, 1.6% (1/63) were resistant to fosfomycin, and 3.2% (2/63) were resistant to nitrofurantoin. The most common multidrug-resistance pattern (22.9%; 30/131) was to ampicillin/sulbactam, ampicillin, cefazolin, ciprofl oxacin, and trimethoprim/sulfamethoxazole. CONCLUSIONS Uropathogenic E. coli resistance to the antibiotics most frequently used in community medical practice is quite common, and extended-spectrum beta-lactamase- producing bacteria is the mechanism for beta-lactam antibiotic resistance. Multidrug-resistance patterns include resistance to the antibiotics most used in community-acquired infections. Fosfomycin and nitrofurantoin are the most active in extendedspectrum beta-lactamase producing bacteria. All the isolates were susceptible to colistin.