Etiologies of community-onset urinary tract infections requiring hospitalization and antimicrobial susceptibilities of causative microorganisms

Abstract

Background: Community-onset urinary tract infections (CoUTIs) are the most common bacterial infections, and a decline in antibiotic susceptibility causes many clinical challenges. Adequate empiric antibiotic treatment can decrease unnecessary hospital stays and complications, while reducing the antimicrobial resistance progression. Methods: From October 2014 to April 2015, we retrospectively enrolled patients who were at least 18 years old and required hospitalization for CoUTIs. Demographic variables of these patients, and uropathogens and their antimicrobial susceptibilities were evaluated. Results: In total, 457 patients were enrolled in this study. Their mean age was 71.9 years, and 35.2% of the patients were male. Escherichia coli (54.5%) was the most common uropathogen, followed by Klebsiella pneumoniae (13.1%), Enterococcus spp. (7.1%), Pseudomonas aeruginosa (4.6%), and Proteus mirabilis (3.5%). Bacteremia was present in 25.2% of patients. Diabetes mellitus and acute kidney injury at admission were risk factors for CoUTIs with concomitant bacteremia. Among the UTI-associated bloodstream strains, E. coli (53.1%) was also the most predominant pathogen, followed by K. pneumoniae (11.3%), Staphylococcus aureus (6.1%), and P. mirabilis (4.3%). The overall susceptibility of cefazolin was 62.8%, ceftriaxone 71.4%, ceftazidime 82.8%, flomoxef 82%, cefepime 94.5%, ampicillin–sulbactam 41.6%, piperacillin–tazobactam 85%, levofloxacin 65.2%, trimethoprim–sulfamethoxazole 61.5%, imipenem 92.3%, gentamicin 76.1%, and amikacin 97.5%. Cefazolin-susceptible isolates could be found more frequently among patients who are less than 65 years of age and without diabetes mellitus, had no UTI episode in the past year, and have no bacteremia risk. Patients with nasogastric tube retention more commonly experienced antimicrobial resistance to all the third-generation cephalosporins. Conclusion: Third-generation cephalosporins effectively treated CoUTIs. However, patients with nasogastric tube retention more commonly experienced cephalosporin resistance. Cefepime, imipenem, and amikacin may be used in patients with higher antimicrobial resistance. In selected patients, cefazolin may still be an adequate drug of choice for CoUTIs. Keywords: antibiotic susceptibility, cefazolin, community onset, third-generation cephalosporin, urinary tract infection