Bacterial etiology and antimicrobial resistance pattern of community-acquired urinary tract infection in older adults

Background

Urinary tract infections (UTIs) are a significant cause of morbidity in elderly individuals and remain a persistent challenge for medical professionals. This study aimed to identify the bacteria causing community-acquired (CA) UTIs in older patients, determine their antimicrobial resistance patterns, assess the prevalence of polymicrobial infections, and identify the risk factors.

Methods

Urine samples were obtained from patients with symptomatic UTIs and then cultured on blood and MacConkey agar. Positive cultures were identified and tested for antimicrobial susceptibility using the VITEK 2 system.

Results

Polymicrobial infections were found in 69/427 (16.16 %) of older patients with CA-UTIs and associated with diabetes (p = 0.007), previous antimicrobial use (p = 0.025), and recurrent urinary infections (p = 0.043). Escherichia coli was the leading pathogen (57.26 %), and Klebsiella pneumoniae was identified in 15.32 % of CA-UTIs. Escherichia coli was more common in non-diabetic patients (60.81 %) than diabetes (43.69 %). However, the rates of Klebsiella species were higher in diabetes (20.39 %) than non-diabetes (14.50 %). Gram-negative uropathogens showed 49.89 % resistance to amoxicillin-clavulanic acid, while imipenem is the least resistant (7.19 %). The gram-positive uropathogens were resistant to 9.80 % of linezolid and highly resistant to erythromycin (74.51 %), tetracycline (72.55 %), and gentamicin (70.59 %).

Conclusions

Escherichia coli isolates were the predominant bacteria in the elderly and highly resistant to amoxicillin-clavulanic. The most effective drug against gram-negative bacteria was imipenem, while linezolid proved potently effective against gram-positive bacteria. Diabetes, previous antimicrobial use, and recurrent urinary infections are risk factors for polymicrobial UTIs.