Age-linked variations in UTI pathogens and antibiotic resistance patterns may guide empirical antimicrobial treatment

24 April, 2022

Urinary tract infections (UTIs) are one of the most common reasons for hospital visits worldwide and are associated with significant economic burden.1-3 In the United States alone, an estimated 2.8 billion USD was spent on healthcare costs associated with UTIs in 2011.2 Another estimate from 2007 which included missed work hours draws this number at approximately 3.5 billion USD.3 These numbers continue to grow as disease incidence increases, with a 52% surge between 1998–2011.2

Rising antimicrobial resistance has resulted in limited effective treatment options for UTIs, making antimicrobial stewardship all the more important.2 Risk factors and clinical presentation of UTI vary in different age categories, with differing trends in causative pathogens and/or antimicrobial susceptibility.4 Such age-dependent differences will warrant treatment selection according to age categories, and will be an important step forward in making more informed selection of empirical antimicrobial therapy.4

Researchers from Peking University First Hospital, Beijing, China investigated UTI causative agents and antimicrobial resistance patterns across age groups in a total of 13,308 UTI patients.4 Data was collected retrospectively, and included all positive urine culture results from non-repetitive UTI patients recorded in their hospital from January 2009 to December 2020.4 Aetiological profiles were sorted based on age category (newborn, ≤28 days; paediatric, 29 days to ≤14 years; adult, >14 to ≤65 years; geriatric, >65 years) and antimicrobial resistance rates for top five causative pathogens were analysed.4

Key findings from their research were4:

  • Escherichia faecium was the dominant cause in newborns (45%, N=105) and Escherichia coli was the dominant strain in paediatric (34%, N=362), adult (43%, N=3,416) and geriatric (40%, N=1,617) cases.
  • Aetiological profiles differed across age categories when stratified by sex (male and female) and ward type (outpatient, inpatient, ICU and emergency).
    • While coli was the most common causative agent in both males and females, females showed higher proportion of E. coli cases, whereas causative agents were more diverse among males.
    • Among females, incidence of UTIs caused by coli increased with age (newborns, 19%; paediatric, 41%; adults and geriatric, 50%). In males, this incidence was relatively stable across all ages (between 20–27% across all categories).
    • In newborns, faecalis was more dominant in females (51% versus 39% in males).
    • Overall, E. coli accounted for 50% and 51% of adult and geriatric outpatients respectively, and faecium was the most common ICU strain (adult, 26%; geriatric, 21%) and emergency cases (adult, 28%; geriatric, 22%).*
  • E. coli, Klebsiella pneumoniae, Escherichia faecalis, E. faecium, and Pseudomonas aeruginosa were the five most common pathogens in all age groups.
    • E. coli resistance to antibiotic cocktails of cefoperazone-sulbactam and piperacillin-tazobactam was low in all ages.
    • In geriatric patients, pneumoniae showed higher rates of resistance to other cephalosporins, carbapenems, and fluoroquinolones.
    • Across all ages, faecium was more resistant than E. faecalis.
    • Rates of multidrug resistance increased with age and was more severe in geriatric patients.

Aetiological data and resistance profiles in UTI as highlighted in this study could provide the empirical evidence needed to select more appropriate treatments and provide timely intervention for different age sub-populations.1,4 Especially among paediatric and geriatric patients where patterns vary, it is important to consider different antimicrobial therapies before beginning treatment.4 The findings of this study could inform future UTI treatment guidelines to consider the aetiological and antimicrobial resistance patterns in different sub-populations.

*Newborns and paediatric cases were not included in this analysis due to low sample size when stratified according to ward type.





  1. Odoki M, et al. Int J Microbiol 2019;2019:4246780.
  2. Simmering JE, et al. Open Forum Infect Dis 2019;4:ofw281.
  3. Flores-Mireles AL, et al. Nat Rev Microbiol 2015;13:269–284.
  4. Huang L, et al. Front Microbiol 2022;12:813145.