Human bocavirus (HBoV) 1 is considered an important respiratory pathogen, while the role of HBoV2-4 in clinical disease remains somewhat controversial. Since, they are characterized by a rapid evolution, worldwide surveillance of HBoVs’ genetics is necessary. This study explored the prevalence of HBoV genotypes in pediatric patients with respiratory tract infection in Croatia and studied their phylogeny. Using multiplex PCR for 15 respiratory viruses, we investigated 957 respiratory samples of children up to 18 years of age with respiratory tract infection obtained from May 2017 to March 2021 at two different hospitals in Croatia. Amplification of HBoV near-complete genome or three overlapping fragments was performed, sequenced, and their phylogenetic inferences constructed. HBoV was detected in 7.6% children with a median age of 1.36 years. Co-infection was observed in 82.2% samples. Sequencing was successfully performed on 29 HBoV positive samples, and all belonged to HBoV1. Croatian HBoV1 sequences are closely related to strains isolated worldwide, and no phylogenetic grouping based on mono- or co-infection cases or year of isolation was observed. Calculated rates of evolution for HBoV1 were 10⁻⁴ and 10⁻⁵ substitutions per site and year. Recombination was not detected among sequences from this study.

Human bocavirus (HBoV) has emerged as a significant pathogen primarily associated with respiratory infections in children. This study aimed to evaluate the clinical relevance of HBoV infection by quantifying viral loads in nasopharyngeal swabs from hospitalized children with acute respiratory infections (ARIs) and investigating correlations with clinical outcomes. A total of 957 children were tested, with HBoV detected in 73 cases (7.6%), either as a sole infection or co-infection with other respiratory viruses. Quantitative polymerase chain reaction (qPCR) was employed to measure viral load, and a threshold of 10⁴ copies/mL was used to differentiate high and low viral concentrations. Results have shown that children with lower respiratory tract infections (LRTIs) had significantly higher viral loads, most notably in cases where HBoV was the sole pathogen. Additionally, children with pre-existing health conditions were more likely to have elevated HBoV concentrations compared to those who were previously healthy. Children with higher viral loads were more likely to require oxygen supplementation and receive empirical antibiotic therapy, indicating a more severe clinical course. This study underscores the importance of considering HBoV viral load in clinical diagnostics, as higher concentrations were associated with more severe presentations, including the need for oxygen support. Future research should focus on refining diagnostic thresholds and exploring HBoV’s role in co-infections to enhance patient care strategies.

Human bocavirus (HBoV) is an important respiratory pathogen, especially in children, but it is often found in co-detection with other respiratory viruses, which makes the diagnostic approach challenging. We compared multiplex PCR and quantitative PCR for HBoV with multiplex tandem PCR (MT-PCR) in 55 cases of co-detection of HBoV and other respiratory viruses. In addition, we investigated whether there is a connection between the severity of the disease, measured by the localization of the infection, and amount of virus detected in the respiratory secretions. No statistically significant difference was found, but children with large amount of HBoV and other respiratory virus had a longer stay in hospital.

Parvovirus B19 (B19V) infection during pregnancy represents a significant clinical concern due to its potential impact on the fetus and pregnancy outcome. We analyzed temporal, spatial, and seasonal B19V seroepidemiology in childbearing-aged and pregnant women in Croatia over 10 years (2015–2024). A total of 976 women who underwent routine TORCH screening were included. The overall B19V IgG and IgM seroprevalence was 63.7 and 8.7%, respectively, with significant temporal differences (IgG 36.8–72.3%, IgM 1.3–18.4). Significant differences in the IgG seropositivity were observed among age groups, from 42.3% in the 16–20 group to 72.7% in the 36–40 group. Spatial analysis showed no significant differences in the IgG or IgM seroprevalence between regions (City of Zagreb/Northern Croatia, Pannonian and Adriatic Croatia) and settlements (urban, suburban/rural). Additionally, seropositivity did not differ significantly in relation to obstetric history. In a logistic regression model, age was a significant predictor for IgG seroprevalence, with each additional year of age associated with increased odds of IgG seropositivity. Year, region, and settlement type were not significant predictors, indicating no evidence of temporal trends, regional differences, or differences between urban and rural settings after adjusting for age. Year of sampling, age, and region were significant predictors for IgM positivity. Acute infections were most common from March to July (61.2%) and December (9.4%), with regional variations in seasonal prevalence patterns. Given that screening in pregnancy is not routinely recommended, the high susceptibility to B19V observed in Croatia supports targeted serologic testing in women with clinical symptoms, known exposure, or occupational risk.

The rise in antimicrobial-resistant Neisseria gonorrhoeae (NG) strains poses major challenges to gonorrhea treatment worldwide. Ceftriaxone remains the first-line antibiotic therapy; however, emerging resistance, particularly driven by the mosaic penA 60.001 allele, necessitates vigilant surveillance. This study assesses the antimicrobial susceptibility patterns of NG isolates in the northwestern region of Croatia and evaluates the correlation between phenotypic susceptibility testing for extended-spectrum cephalosporins (ESC) and genotypic detection of the penA 60.001 allele. A total of 39 clinical NG-positive specimens by a multiplex PCR panel for urogenital infections were collected between 1 July 2022, and 30 June 2024. Phenotypic antimicrobial susceptibility testing was performed using the Etest method. Genotypic detection of ceftriaxone resistance determinants was performed using a multiplex nested PCR assay. All NG isolates were susceptible to ceftriaxone and cefixime. High resistance rates were observed for ciprofloxacin (70.6%), tetracycline (44.1%), and azithromycin (20.6%). Mutations in the penA gene associated with decreased susceptibility to ceftriaxone were detected in three samples, although phenotypic resistance was not observed. The high resistance rates to ciprofloxacin, tetracycline, and azithromycin limit their use for empirical therapy in Croatia. While ceftriaxone remains effective, the detection of penA mutations highlights the need for ongoing surveillance.