The sero-prevalence and virulence determinants of Klebsiella pneumoniae isolated from urine in outpatient units: a 20-year collection from Taiwan as a herald for serotype vaccine selection.

UNLABELLED: This study analyzed 570 non-duplicate Klebsiella pneumoniae isolates (n = 570) from outpatient urine cultures collected between 1998 and 2018 through the Taiwan Surveillance of Antimicrobial Resistance (TSAR) program. Serotyping, antimicrobial susceptibility testing, and virulence gene profiling were performed. Results were compared with 521 previously reported bloodstream isolates collected in 1998, 2008, and 2018. The most common urinary tract infection (UTI) serotypes were K2, K64, K62, K1, and K25, with non-typeable isolates comprising 19.3%. Compared to bloodstream isolates, non-typeable strains were more frequent in UTIs, while K1 and K2 were more common in bloodstream infections. Resistance to cephalosporins, carbapenems, and ciprofloxacin increased significantly after 2014. K64 showed over 72.2% resistance to cephalosporins and rising quinolone resistance. In contrast, K1 and K2 exhibited low resistance but carried the highest burden of virulence genes. Non-typeable isolates lacked virulence determinants, suggesting lower pathogenic potential. This 20-year analysis highlights the distinct serotype and resistance patterns in community-onset UTI isolates in Taiwan and underscores the importance of incorporating prevalent, drug-resistant serotypes into future vaccine strategies.

IMPORTANCE: Klebsiella pneumoniae is an important cause of urinary tract infections in the community. With rising resistance to commonly used antibiotics, preventive strategies, such as vaccination, are urgently needed. This 20-year analysis provides detailed data on the distribution of bacterial types and their resistance patterns in Taiwan. The findings offer valuable insight for selecting vaccine targets that cover the most prevalent and drug-resistant strains, supporting the development of effective preventive tools against multidrug-resistant infections.