Vívian Santos Galvão

Klebsiella pneumoniae poses a significant public health threat, but the relationship between community-acquired (CA) infections and environmental isolates remains poorly understood. Therefore, this study aimed to assess whether K. pneumoniae from CA infections share microbiological and molecular features with isolates recovered from an urban river in Salvador, Brazil. A total of 115 isolates, including 65 from CA infections and 50 from river water, were analyzed using antimicrobial susceptibility testing, β-lactamase and virulence gene detection, and multilocus sequence typing (MLST). Resistance rates were similar between groups, including multidrug resistance (24.6% vs. 22.0%; p > 0.05) and carbapenem resistance (4.6% vs. 4.0%; p > 0.05). β-lactamase gene detection was consistent with observed resistance patterns, with bla _CTX−M detected in 18.5% of CA isolates and 12.0% of river isolates, while bla _KPC−2 (3.1% vs. 2.0%) and bla _NDM−1 (1.5% vs. 2.0%) occurred at comparable frequencies. However, hypervirulent K. pneumoniae isolates were identified only among CA infections (4.6%). MLST revealed high clonal diversity, with 88 sequence types (STs), including 14 novel STs, with most STs being singletons. Four STs were shared between groups, including the high-risk lineages ST11 and ST307. These findings indicate that clinically relevant K. pneumoniae lineages, including high-risk, occur beyond healthcare settings, with urban aquatic environments serving as potential environmental reservoirs.

Urinary tract infection (UTI) is the most common bacterial infection globally and is often treated empirically in community settings, contributing to antimicrobial resistance. Uropathogenic E. coli (UPEC) is the leading cause of community‐acquired UTIs (CA‐UTIs), yet data on its clinical and molecular characteristics remain limited. To investigate the clinical and microbiological features of CA‐UTIs, focusing on antimicrobial resistance, phylogenetic groups, virulence genes, and clonal profiles. Randomly selected E. coli isolates from CA‐UTI cases underwent antimicrobial susceptibility testing. PCR was used to detect β‐lactamase genes, phylogenetic groups, and key virulence factors. MLST was used for clonal typing. Clinical and demographic data were obtained through structured interviews. Among 98 CA‐UPEC isolates, most were from female patients (95.9%), median age 48 years. High resistance was observed to ampicillin (50.0%), trimethoprim‐sulfamethoxazole (34.7%), and fluoroquinolones (33.7%), while resistance to nitrofurantoin and fosfomycin was low (1%). Multidrug resistant (MDR) strains accounted for 24.5%, with 6.1% being ESBL producers, all harboring bla _{CTX‐M‐type} genes. Phylogenetic group B2 (48.0%) carried the most virulence genes, while group A had more MDR strains. Common virulence genes included fimH (95.9%), PAI IV ₅₃₆ (77.6%), and fyuA (76.5%). Genes aer , and iutA were linked to MDR, while papC, sfa, hlyA were more common in non‐MDR isolates. ST1193, a high‐risk clone, was the most prevalent (25.0%), found only among MDR strains. ST73 and ST127 were associated with multiple virulence genes but were non‐MDR. Nitrofurantoin and fosfomycin remain effective options for CA‐UTIs. Continuous surveillance is vital to guide treatment and track resistance trends.

Klebsiella pneumoniae is one of the leading causes of bloodstream (BSI) and urinary tract infections (UTI), but limited data is available regarding community-acquired (CA) infections. This study characterized the clinical aspects of CA-BSI and CA-UTI caused by K. pneumoniae and the molecular features of isolates, including their resistance profiles. Sixty-five isolates (CA-BSI, n = 24; CA-UTI, n = 41) underwent antimicrobial susceptibility testing, β-lactamase and virulence gene assessment, capsular genotyping, and molecular typing. Older age, male gender, and comorbidities, particularly kidney disease, were significantly associated with CA-BSI. The MDR and carbapenem resistance rates for K. pneumoniae from CA infections were 24.6% and 4.6%, respectively. CA-BSI isolates were more antibiotic-resistant and had a higher proportion of ESBL-producing (37.5% versus 9.8%) and MDR isolates (45.8% versus 12.2%) than CA-UTI. The bla _{CTX−M−like} or bla _KPC−like genes was found in all ESBL-producing isolates, while bla _KPC−like and bla _NDM−like were detected exclusively in CA-BSI strains. The isolates’ virulence profiles were similar between the groups, although one CA-BSI and two CA-UTI isolates presented hypervirulence biomarkers. A high clonal diversity was observed, with a majority of MDR (81.3%) (ST11, ST15, ST101, ST258, ST307, and ST6852) and hypervirulent (2/3) (ST23 and ST65) isolates being high-risk pandemic clones in humans. Our data highlight the high prevalence of MDR K. pneumoniae in CA infections in Brazil, with CA-BSI showing significant differences in resistance profiles compared to CA-UTI.

Urinary tract infection (UTI) is one of the most common bacterial infections among humans. Urine culture is the gold standard diagnostic method for UTI; however, the dipstick test for nitrite is a widely used method signalling the presence of urinary nitrate-reducing bacteria. Unlike the gold standard, the dipstick test is easy to perform, while it is also less time-consuming and less expensive, and produces a result in a few minutes. This study investigates the sensitivity of the dipstick test for nitrite compared with the Griess test in urine samples from UTI caused by Enterobacterales species. We used the Griess test, which is the gold standard in nitrite measurement, to determine the sensitivity of the nitrite dipstick test. Semiquantitative urine culture was performed using standard procedures, and Enterobacterales identification was performed by manual conventional biochemical tests. In the first sample selection, 3 % (8/267) of urine samples suspected of UTI, analysed from March to April 2016, were nitrite-negative by dipstick test but positive for Enterobacterales in the urine culture. In the second sample selection, 5 % (2/44) of urine samples from October to December 2022 were also nitrite-negative but showed urine Enterobacterales isolation. All nitrite-negative dipstick results were consistent with the Griess test. Escherichia coli was the most prevalent bacterium, followed by Klebsiella pneumoniae, independent of sample selection. The dipstick test is a safe alternative for investigating nitrite in urine samples. We believe that the cause of nitrite-negative results is a lack of dietary nitrate, dilution of urine and exogenous interference (e.g. ascorbic acid). These findings support the idea that standard urine culture is necessary to rule out UTI.