Urinary Tract Infections in Children – Microbiological Challenges and Mechanisms of Bacterial Resistance

Urinary tract infections (UTIs) are common both in adults and particularly in children. It is estimated that the number of UTI cases has reached 4.49 billions in 2021, while common and often successfully treated with antibiotics UTIs pose the risk for sepsis, kidney complications and occurrence of antibiotic-resistant microbial strains. Symptoms of UTIs in children vary from non-specific, such as fever and lethargy, to specific such as difficult voiding, dysuria and suprapubic, abdominal or lumbar pain. Urinary tract infections may be lower (cystitis) or upper (pyelonephritis) and the etiological diagnosis is based on urinalysis and urine culture. There are several resistance mechanisms that commonly occur across different bacterial species (some of them being found in the same family) responsible for pediatric UTIs. For instance, an extensive mechanism of resistance is the production of beta-lactamase. Gram-negative bacilli may also develop polymyxin resistance; Staphylococcus aureus may become methicillin resistant and vancomycin resistance may appear in both S. aureus and Enterococcus spp. The present review presents the mechanisms of resistance of bacteria involved in UTIs in children.