Biomarkers innovation in urinary tract infections: Insights into pathophysiology, antibiotic resistance, and clinical applications

Table 1 Commonly detected pathogens causing urinary tract infections

Bacteria	Factors of UTI
Escherichia coli	The most common cause of UTI; the pathogen ascends from the urethra to the bladder or descends from the kidneys to lower urinary tract
Staphylococcus saprophyticus	Present as skin flora; cause UTIs, especially in young women
Enterococcus faecalis	It is an opportunistic pathogen; associated with complicated UTIs, especially in hospitalized patients
Pseudomonas aeruginosa	Cause antibiotic resistance; form biofilms, infect patients with catheters or those who are immunocompromised
Klebsiella pneumoniae	Affect individuals with underlying health conditions that are resistant to multiple antibiotics
Proteus mirabilis	Associated with catheter use and urinary retention; produces urease, which contributes to struvite stones
Enterobacter spp.	Cause UTIs in hospitalized patients; resistant to multiple antibiotics
Coagulase-negative Staphylococci spp.	Present in skin flora; cause UTIs in immunocompromised individuals or those with catheters

UTI: Urinary tract infections.

Table 2 Clinical applications of biomarkers in urinary tract infections

Biomarkers	Clinical application	Ref.
NGAL	Guides UTI diagnosis and therapy, reduces unnecessary antibiotic use, and serves as a marker for disease severity	[23]
KIM-1	Used for diagnosis and prognosis of renal diseases	[34]
IL-8	Aids in diagnosing neonatal sepsis and serves as a marker for inflammation	[41]
IL-6	Evaluate impact of therapeutic agents on urinary bacteria and systemic inflammation	[41]
XO	Measures nitrite levels during UTI, allowing real-time monitoring of bacterial activity and treatment efficacy	[53]
cfDNA and Tr-DNA	Enables early identification of bacterial infections, particularly in UTIs and post-transplant monitoring	[59]
HBP	Functions as an auxiliary marker for detecting bacteremia and assessing severity of infection	[44]
PCT	Facilitates early diagnosis and differentiation of bacterial UTIs	[63]
LBP	Serves as a biomarker for diagnosing febrile UTIs, particularly in pediatric patients	[51]

NGAL: Neutrophil gelatinase-associated lipocalin; KIM-1: Kidney Injury molecule-1; IL: Interleukin; HBP: Heparin-binding protein; LBP: Lipopolysaccharide-binding protein; PCT: Procalcitonin; XO: Xanthine oxidase; cfDNA: Cell-free DNA; trDNA: Transrenal DNA; UTI: Urinary tract infections.

Table 3 Commonly encountered uropathogens with their susceptible antibiotics

Bacteria	Antibiotics
Escherichia coli	Nitrofurantoin, Trimethoprim-sulfamethoxazole, Fosfomycin
Staphylococcus saprophyticus	Nitrofurantoin, Norfloxacin Trimethoprim-sulfamethoxazole
Enterococcus faecalis	Ampicillin, Vancomycin (for resistant strains)
Pseudomonas aeruginosa	Ceftazidime, Piperacillin-tazobactam, Meropenem, Ciprofloxacin, Aminoglycosides
Klebsiella pneumoniae	Ceftriaxone, Piperacillin-tazobactam, Fluoroquinolones (if susceptible), Aminoglycosides
Proteus mirabilis	Trimethoprim-sulfamethoxazole, Ciprofloxacin
Enterobacter spp.	Cefepime (less resistant strains), Fluoroquinolones (susceptible), Aminoglycosides (serious infections)
Coagulase-negative Staphylococci spp.	Vancomycin (for resistant strains), Oxacillin (if susceptible)