Urinary tract infection (UTI), which is typically caused by Escherichia coli (E. coli), is an insufficiently recognized co-morbidity among patients with chronic obstructive pulmonary disease (COPD). Adequate treatment can be complicated by resistance of the causative pathogen to beta-lactam antibiotics, which often produce beta-lactamase enzymes that destroy the antibiotic. The beta-lactamase family of enzymes is extremely diverse, including different types of enzyme and mutant forms. In this study, we analyzed 580 patients with COPD (236 females and 344 males) and thus found 218 patients with co-morbid UTIs, including 58 patients with UTI caused by E. coli (38 females and 20 males). We also investigated cases of uncomplicated symptomatic and asymptomatic UTI caused by E. coli and the presence of resistance to beta-lactam antibiotics among those patients. The E. coli strains resistant to beta-lactam antibiotics were selected for their ability to grow on selective media, before DNA microarrays were applied for specific identification of three beta-lactamase gene types (i.e., TEM, SHV and CTX-M). Overall, 83% of E. coli strains responsible for UTIs in COPD patients carried extended-spectrum beta-lactamase genes. The most prevalent were those producing CTX-M, with CTX-M-15 being predominant. The rare CTX-M-27 and TEM-15 genes were also detected in two samples. Three samples contained several extended-spectrum beta-lactamase genes simultaneously (CTX-M-15 or CTX-M-14 plus SHV-5 or TEM-15). This high prevalence of resistant E. coli strains necessitates rational antibiotic selection when treating UTI to prevent COPD exacerbations. Additionally, antibiotic therapy should be aligned with and adapted to existing and potential COPD co-morbidities.
Keywords: Escherichia coli; antibiotic resistance; beta-lactamases; chronic obstructive pulmonary disease; urinary tract infection.