UNLABELLED: The paper presents the study of a set of isolates of Streptococcus pneumoniae, which comprised two heterogeneous subpopulations, one of which was susceptible and the other resistant to optochin. The aim of the study was to compare the results of serotyping, multilocus sequence typing (MLST), ribosomal multilocus sequence typing (rMLST), and variation analysis of these subpopulations and to investigate the genetic probable causes of optochin resistance. The strains studied were cultured from samples taken from patients with invasive pneumococcal disease in the Czech Republic in 2019 and 2020. A total of 10 studied pairs of isolates were subject to serotyping and whole-genome sequencing (WGS). None of the typing methods (serotyping, MLST, or rMLST) applied to pairs of optochin-susceptible and optochin-resistant isolates revealed differences in serotype, sequence type, or ribosomal sequence type. The WGS data analysis identified point mutations in ATP (adenosine triphosphate) synthase genes in 8 of the 10 optochin-resistant isolates. In seven optochin-resistant isolates, the mutation was found in the atpC gene and in one isolate in the atpA gene. One of the mutations in the atpC gene has not yet been published in the literature; it is a mutation at position 143T > C with an amino acid change of Val48Ala. In 8 out of the 10 optochin-resistant isolates, the possible genetic basis for resistance was identified, involving point mutations in the atpA and atpC genes. In the remaining two isolates, no clear genetic explanation for the optochin resistance in S. pneumoniae was found, based on current knowledge. IMPORTANCE: Globally, among the most fundamental tests used for the identification of Streptococcus pneumoniae isolates is determining susceptibility to optochin. In the last 2 decades, optochin-resistant strains have been frequently reported in the literature, which can lead to the misidentification of S. pneumoniae. This study compares whole-genome sequencing data of optochin-susceptible and optochin-resistant subpopulations of S. pneumoniae isolates and investigates the genetic probable causes of resistance in the genomes of optochin-resistant subpopulations.

• Klíčová slova
• Streptococcus pneumoniae, optochin, whole genome sequencing,
• MeSH
• antibakteriální látky * farmakologie   MeSH
• bakteriální léková rezistence * genetika   MeSH
• chinin farmakologie   analogy a deriváty   MeSH
• genom bakteriální genetika   MeSH
• lidé MeSH
• mikrobiální testy citlivosti * MeSH
• multilokusová sekvenční typizace * metody   MeSH
• pneumokokové infekce * mikrobiologie   MeSH
• sekvenování celého genomu * metody   MeSH
• sérotypizace metody   MeSH
• Streptococcus pneumoniae * genetika   izolace a purifikace   účinky léků   klasifikace   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• srovnávací studie MeSH
• Geografické názvy
• Česká republika MeSH
• Názvy látek
• antibakteriální látky * MeSH
• chinin MeSH
• ethylhydrocupreine MeSH Prohlížeč

Medical students are exposed to the hospital environment and patients during their studies, increasing the risk of exposure to virulent and antibiotic-resistant isolates of Staphylococcus aureus. The aim of the study is to determine the prevalence of Staphylococcus aureus among medical students who have varying levels of exposure to the hospital environment to provide valuable insights into the risk of colonization and transmission. Nasal swabs and fingerprints were obtained and cultured on a selective medium for staphylococci. The obtained isolates were confirmed as methicillin-sensitive S. aureus (MSSA) or methicillin-resistant (MRSA) using PCR. Antibiotic resistance, the presence of virulence genes including enterotoxin encoding genes, and spa typing were performed. Among pre-clinical students, MSSA was detected on the nose in 45.2% and on the fingerprints in 10.6% of the participants. Among clinical students, MSSA was detected on the nose in 42.0% and on the fingerprints in 25.4%. Only one MRSA isolate was obtained. Genes seg and sei were the most frequently detected in both student groups, with their presence in over 40% of isolates among clinical students. The eta and etb genes were mainly detected from the nose in both student groups. In pre-clinical students, S. aureus carrying eta gene occurred in 6.4% and etb in 8.5%. In clinical students, the occurrence was 5.1% for eta and 8.5% for etb. The tst gene was identified only in the nose and fingerprints of the clinical student group. The most frequently observed resistance was to clindamycin and erythromycin. In total 58 different spa types were identified. High rates of asymptomatic MSSA carriage were observed in both groups of medical students. Detected MSSA strains showed a high degree of genetic variability, with a number of them carrying the virulence and antibiotic resistance genes. Although students do not exhibit increased risk to their patient's, increased hygiene is required in asymptomatic carriage personnel. The overall prevalence of MRSA was low, with a minimal risk of spread.

• Klíčová slova
• Spa type, Staphylococcus aureus, Antibiotic resistance, MRSA, Medical students, Virulence genes,
• MeSH
• antibakteriální látky farmakologie   MeSH
• dospělí MeSH
• faktory virulence * genetika   MeSH
• lidé MeSH
• methicilin rezistentní Staphylococcus aureus genetika   izolace a purifikace   účinky léků   klasifikace   MeSH
• mikrobiální testy citlivosti MeSH
• mladý dospělý MeSH
• přenašečství * mikrobiologie   epidemiologie   MeSH
• prevalence MeSH
• stafylokokové infekce * mikrobiologie   epidemiologie   MeSH
• Staphylococcus aureus * genetika   izolace a purifikace   účinky léků   klasifikace   MeSH
• studenti lékařství * MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antibakteriální látky MeSH
• faktory virulence * MeSH

The main aim of this study was to determine expanded sequence types (eSTs) of Ureaplasma species (U. spp.). DNA isolated from the amniotic fluid of pregnancies complicated by preterm prelabor rupture of membranes (PPROM) using an expanded multilocus sequence typing scheme. Additionally, the study sought to examine whether phylogenetic subgroups of U. spp. DNA differ with respect to maternal demographic and clinical parameters and selected aspects of short-term neonatal morbidity. This retrospective cohort study was focused on singleton pregnancies complicated by PPROM occurring between the gestational ages of 24+0 and 36+6 weeks, where amniocentesis was conducted to assess the intra-amniotic environment and the presence of U. spp. DNA in the amniotic fluid samples was confirmed. The stored aliquots of U. spp. DNA were used to assess differences in nucleotide sequences in six U. spp. genes (ftsH, rpL22, valS, thrS,ureG, and mba-np1) using the eMLST scheme. The expanded multilocus sequence typing scheme was performed in 73 samples of U. spp. DNA isolated from pregnancies complicated by PPROM. In total, 33 different U. spp. DNA eSTs were revealed, 21 (#20, 233-244, 248-251, 253, 255, 259, and 262) of which were novel. The most frequently identified eST was #41, identified in 18% (13/73) of the aliquots. Based on their genetic relationships, the U. spp. DNA was divided into two clusters and four subgroups [cluster I (U. parvum): A, 43% (n = 31); B, 15% (n = 11); and C, 26% (n = 19); cluster II (U. urealyticum): 1; 16% (n = 12)]. Cluster II had a higher rate of polymicrobial findings than cluster I (58% vs 16%; p = 0.005), while subgroup A had the highest rate of concomitant Mycoplasma hominis in the amniotic fluid samples (66%; p = 0.04). In conclusion, Ureaplasma spp. DNA obtained from PPROM consisted of 33 different eSTs of U. spp. DNA. No differences in maternal and neonatal characteristics were found among the phylogenetical subgroups of U. spp. DNA, except for a higher rate of polymicrobial amniotic fluid findings in those with U. urealyticumand the concomitant presence of M. hominis in the amniotic fluid in those with the presence of U. parvum.

• Klíčová slova
• Genital mycoplasma, Microbial invasion of the amniotic cavity, Molecular biology, Mollicutes, Morbidity, Neonates, Preterm delivery, Sequencing,
• MeSH
• DNA bakterií analýza   genetika   MeSH
• dospělí MeSH
• fylogeneze MeSH
• gestační stáří MeSH
• infekční komplikace v těhotenství mikrobiologie   MeSH
• lidé MeSH
• multilokusová sekvenční typizace * MeSH
• plodová voda * mikrobiologie   MeSH
• předčasný odtok plodové vody * mikrobiologie   MeSH
• retrospektivní studie MeSH
• těhotenství MeSH
• Ureaplasma * genetika   izolace a purifikace   MeSH
• ureaplasmatické infekce * mikrobiologie   MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• těhotenství MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• DNA bakterií MeSH

BACKGROUND: The salmonid pathogen Flavobacterium psychrophilum poses a significant economic threat to global aquaculture, yet our understanding of its genetic and phenotypic diversity remains incomplete across much of its geographic range. In this study, we characterise the genetic and phenotypic diversity of 70 isolates collected from rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo trutta m. fario) from fish farms in the Czech Republic between 2012 and 2019 to compare their genomic content with all draft or complete genomes present in the NCBI database (n = 187). RESULTS: The Czech isolates underwent comprehensive evaluation, including multiplex PCR-based serotyping, genetic analysis, antimicrobial resistance testing, and assessment of selected virulence factors. Multiplex PCR serotyping revealed 43 isolates as Type 1, 23 as Type 2, with sporadic cases of Types 3 and 4. Multi-locus sequence typing unveiled 12 sequence types (ST), including seven newly described ones. Notably, 24 isolates were identified as ST329, a novel sequence type, while 22 were classified as the globally-distributed ST2. Phylogenetic analysis demonstrated clonal distribution of ST329 in the Czech Republic, with these isolates lacking a phage sequence in their genomes. Antimicrobial susceptibility testing revealed a high proportion of isolates classified as non-wild type with reduced susceptibility to oxolinic acid, oxytetracycline, flumequine, and enrofloxacin, while most isolates were classified as wild type for florfenicol, sulfamethoxazole-trimethoprim, and erythromycin. However, 31 isolates classified as wild type for florfenicol exhibited minimum inhibitory concentrations at the susceptibility breakpoint. CONCLUSION: The prevalence of the Czech F. psychrophilum serotypes has evolved over time, likely influenced by the introduction of new isolates through international trade. Thus, it is crucial to monitor F. psychrophilum clones within and across countries using advanced methods such as MLST, serotyping, and genome sequencing. Given the open nature of the pan-genome, further sequencing of strains promises exciting discoveries in F. psychrophilum genomics.

• Klíčová slova
• Flavobacterium psychrophilum, Antimicrobial susceptibility, Aquaculture, Farmed rainbow-trout, Genetic diversity, Serotypes,
• MeSH
• antibakteriální látky farmakologie   MeSH
• bakteriální léková rezistence genetika   MeSH
• faktory virulence genetika   MeSH
• fenotyp MeSH
• Flavobacterium * genetika   izolace a purifikace   klasifikace   účinky léků   MeSH
• fylogeneze * MeSH
• genetická variace * MeSH
• genom bakteriální genetika   MeSH
• infekce bakteriemi čeledi Flavobacteriaceae * mikrobiologie   veterinární   MeSH
• mikrobiální testy citlivosti MeSH
• multilokusová sekvenční typizace * MeSH
• nemoci ryb * mikrobiologie   MeSH
• Oncorhynchus mykiss * mikrobiologie   MeSH
• pstruh mikrobiologie   MeSH
• sérotypizace MeSH
• vodní hospodářství MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Česká republika MeSH
• Názvy látek
• antibakteriální látky MeSH
• faktory virulence MeSH

Streptococcus uberis is one of the primary causative agents of mastitis, a clinically and economically significant disease that affects dairy cattle worldwide. In this study, we analyzed 140 S. uberis strains isolated from mastitis milk samples collected from 74 cow herds in the Czech Republic. We employed whole-genome sequencing to screen for the presence of antimicrobial resistance (AMR) genes and genes encoding virulence factors, and to assess their genetic relationships. Our analysis revealed the presence of 88 different sequence types (STs), with 41% of the isolates assigned to global clonal complexes (GCCs), the majority of which were affiliated with GCC5. The STs identified were distributed across the major phylogenetic branches of all currently known STs. We identified fifty-one putative virulence factor genes, and the majority of isolates carried between 27 and 29 of these genes. A tendency of virulence factors and AMR genes to cluster with specific STs was observed, although such clustering was not evident within GCCs. Principal component analysis did not reveal significant diversity among isolates when grouped by GCC or ST prevalence. The substantial genomic diversity and the wide array of virulence factors found in S. uberis strains present a challenge for the implementation of effective anti-mastitis measures.

• Klíčová slova
• MLST, antimicrobial resistance genes, intramammary infection, mastitis, phylogenetic tree, sequence type, virulence genes,
• Publikační typ
• časopisecké články MeSH

The MLST scheme currently used for Enterococcus faecium typing was designed in 2002 and is based on putative gene functions and Enterococcus faecalis gene sequences available at that time. As a result, the original MLST scheme does not correspond to the real genetic relatedness of E. faecium strains and often clusters genetically distant strains to the same sequence types (ST). Nevertheless, typing has a significant impact on the subsequent epidemiological conclusions and introduction of appropriate epidemiological measures, thus it is crucial to use a more accurate MLST scheme. Based on the genome analysis of 1,843 E. faecium isolates, a new scheme, consisting of 8 highly discriminative loci, was created in this study. These strains were divided into 421 STs using the new MLST scheme, as opposed to 223 STs assigned by the original MLST scheme. The proposed MLST has a discriminatory power of D = 0.983 (CI95% 0.981 to 0.984), compared to the original scheme's D = 0.919 (CI95% 0.911 to 0.927). Moreover, we identified new clonal complexes with our newly designed MLST scheme. The scheme proposed here is available within the PubMLST database. Although whole genome sequencing availability has increased rapidly, MLST remains an integral part of clinical epidemiology, mainly due to its high standardization and excellent robustness. In this study, we proposed and validated a new MLST scheme for E. faecium, which is based on genome-wide data and thus reflects the tested isolates' more accurate genetic similarity. IMPORTANCE Enterococcus faecium is one of the most important pathogens causing health care associated infections. One of the main reasons for its clinical importance is a rapidly spreading resistance to vancomycin and linezolid, which significantly complicates antibiotic treatment of infections caused by such resistant strains. Monitoring the spread and relationships between resistant strains causing severe conditions represents an important tool for implementing appropriate preventive measures. Therefore, there is an urgent need to establish a robust method enabling strain monitoring and comparison at the local, national, and global level. Unfortunately, the current, extensively used MLST scheme does not reflect the real genetic relatedness between individual strains and thus does not provide sufficient discriminatory power. This can lead directly to incorrect epidemiological measures due to insufficient accuracy and biased results.

• Klíčová slova
• Enterococcus faesium, clonal complex, epidemiology, multilocus sequence typing, whole genome sequenging,
• MeSH
• antibakteriální látky MeSH
• Enterococcus faecium * genetika   MeSH
• grampozitivní bakteriální infekce * epidemiologie   MeSH
• lidé MeSH
• multilokusová sekvenční typizace metody   MeSH
• sekvenování celého genomu MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• antibakteriální látky MeSH

Both temperate and obligately lytic phages have crucial roles in the biology of staphylococci. While superinfection exclusion among closely related temperate phages is a well-characterized phenomenon, the interactions between temperate and lytic phages in staphylococci are not understood. Here, we present a resistance mechanism toward lytic phages of the genus Kayvirus, mediated by the membrane-anchored protein designated PdpSau encoded by Staphylococcus aureus prophages, mostly of the Sa2 integrase type. The prophage accessory gene pdpSau is strongly linked to the lytic genes for holin and ami2-type amidase and typically replaces genes for the toxin Panton-Valentine leukocidin (PVL). The predicted PdpSau protein structure shows the presence of a membrane-binding α-helix in its N-terminal part and a cytoplasmic positively charged C terminus. We demonstrated that the mechanism of action of PdpSau does not prevent the infecting kayvirus from adsorbing onto the host cell and delivering its genome into the cell, but phage DNA replication is halted. Changes in the cell membrane polarity and permeability were observed from 10 min after the infection, which led to prophage-activated cell death. Furthermore, we describe a mechanism of overcoming this resistance in a host-range Kayvirus mutant, which was selected on an S. aureus strain harboring prophage 53 encoding PdpSau, and in which a chimeric gene product emerged via adaptive laboratory evolution. This first case of staphylococcal interfamily phage-phage competition is analogous to some other abortive infection defense systems and to systems based on membrane-destructive proteins. IMPORTANCE Prophages play an important role in virulence, pathogenesis, and host preference, as well as in horizontal gene transfer in staphylococci. In contrast, broad-host-range lytic staphylococcal kayviruses lyse most S. aureus strains, and scientists worldwide have come to believe that the use of such phages will be successful for treating and preventing bacterial diseases. The effectiveness of phage therapy is complicated by bacterial resistance, whose mechanisms related to therapeutic staphylococcal phages are not understood in detail. In this work, we describe a resistance mechanism targeting kayviruses that is encoded by a prophage. We conclude that the defense mechanism belongs to a broader group of abortive infections, which is characterized by suicidal behavior of infected cells that are unable to produce phage progeny, thus ensuring the survival of the host population. Since the majority of staphylococcal strains are lysogenic, our findings are relevant for the advancement of phage therapy.

• Klíčová slova
• Kayvirus, Staphylococcus aureus, abortive infection, bacteriophage evolution, bacteriophage therapy, bacteriophages, cell death, lysogeny, phage resistance, phage therapy,
• MeSH
• lidé MeSH
• lyzogenie MeSH
• membránové proteiny genetika   MeSH
• profágy * genetika   MeSH
• stafylokokové bakteriofágy genetika   MeSH
• stafylokokové infekce * mikrobiologie   MeSH
• Staphylococcus aureus genetika   MeSH
• Staphylococcus MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• membránové proteiny MeSH

Invasive meningococcal disease belongs among the most dangerous infectious diseases in the world. Several polysaccharide conjugate vaccines against serogroups A, C, W and Y are available and two recombinant peptide vaccines against serogroup B (MenB vaccines) have been developed: MenB-4C (Bexsero) and MenB-fHbp (Trumenba). The aim of this study was to define the clonal composition of the Neisseria meningitidis population in the Czech Republic, to determine changes in this population over time and to estimate the theoretical coverage of isolates by MenB vaccines. This study presents the analysis of whole genome sequencing data of 369 Czech N. meningitidis isolates from invasive meningococcal disease covering 28 years. Serogroup B isolates (MenB) showed high heterogeneity and the most common clonal complexes were cc18, cc32, cc35, cc41/44, and cc269. Isolates of clonal complex cc11 were predominately serogroup C (MenC). The highest number of serogroup W isolates (MenW) belonged to clonal complex cc865, which we described as exclusive to the Czech Republic. Our study supports the theory that this cc865 subpopulation originated in the Czech Republic from MenB isolates by a capsule switching mechanism. A dominant clonal complex of serogroup Y isolates (MenY) was cc23, which formed two genetically quite distant subpopulations and which showed constant representation throughout the observed period. The theoretical coverage of isolates by two MenB vaccines was determined using the Meningococcal Deduced Vaccine Antigen Reactivity Index (MenDeVAR). Estimated Bexsero vaccine coverage was 70.6% (for MenB) and 62.2% (for MenC, W, Y). For Trumenba vaccine, estimated coverage was 74.6% (for MenB) and 65.7% (for MenC, W, Y). Our results demonstrated sufficient coverage of Czech heterogeneous population of N. meningitidis with MenB vaccines and, together with surveillance data on invasive meningococcal disease in the Czech Republic, were the basis for updating recommendations for vaccination against invasive meningococcal disease.

• MeSH
• antigeny bakteriální MeSH
• lidé MeSH
• meningokokové infekce * epidemiologie   MeSH
• meningokokové vakcíny * MeSH
• Neisseria meningitidis séroskupiny B * genetika   MeSH
• Neisseria meningitidis * MeSH
• sekvenování celého genomu MeSH
• séroskupina MeSH
• syntetické vakcíny genetika   MeSH
• vakcinace MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Česká republika epidemiologie   MeSH
• Názvy látek
• antigeny bakteriální MeSH
• meningokokové vakcíny * MeSH
• syntetické vakcíny MeSH

The Pseudomonas aeruginosa population has a nonclonal epidemic structure. It is generally composed of a limited number of widespread clones selected from a background of many rare and unrelated genotypes recombining at high frequency. Due to the increasing prevalence of nosocomial infections caused by multidrug-resistant/extensively drug-resistant (MDR/XDR) strains, it is advisable to implement infection control measures. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) are considered the gold standard methods in bacterial typing, despite being limited by cost, staff, and instrumental demands. Here, we present a novel mini-MLST scheme for P. aeruginosa rapid genotyping based on high-resolution melting analysis. Using the proposed mini-MLST scheme, 3,955 existing sequence types (STs) were converted into 701 melting types (MelTs), resulting in a discriminatory power of D = 0.993 (95% confidence interval [CI], 0.992 to 0.994). Whole-genome sequencing of 18 clinical isolates was performed to support the newly designed mini-MLST scheme. The clonal analysis of STs belonging to MelTs associated with international high-risk clones (HRCs) performed by goeBURST software revealed that a high proportion of the included STs are highly related to HRCs and have also been witnessed as responsible for serious infections. Therefore, mini-MLST provides a clear warning for the potential spread of P. aeruginosa clones recognized as MDR/XDR strains with possible serious outcomes. IMPORTANCE In this study, we designed a novel mini-MLST typing scheme for Pseudomonas aeruginosa. Its great discriminatory power, together with ease of performance and short processing time, makes this approach attractive for prospective typing of large isolate sets. Integrating the novel P. aeruginosa molecular typing scheme enables the development and spread of MDR/XDR high-risk clones to be investigated.

• Klíčová slova
• Pseudomonas aeruginosa, high-resolution melting, mini-MLST, molecular epidemiology, strain typing,
• MeSH
• buněčné klony MeSH
• genotyp MeSH
• lidé MeSH
• molekulární epidemiologie metody   MeSH
• multilokusová sekvenční typizace MeSH
• prospektivní studie MeSH
• pseudomonádové infekce * epidemiologie   mikrobiologie   MeSH
• Pseudomonas aeruginosa * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Wolbachia is one of the most abundant intracellular symbionts of arthropods and has profound effects on host biology. Wolbachia transmission and host phenotypes often depend on its density within the host, which can be affected by multiple biotic and abiotic factors. However, very few studies measured Wolbachia density in natural host populations. Here, we describe Wolbachia in the pear psyllid Cacopsylla pyri from three populations in the Czech Republic. Using phylogenetic analyses based on wsp and multilocus sequence typing genes, we demonstrate that C. pyri harbours three new Wolbachia strains from supergroup B. A fourth Wolbachia strain from supergroup A was also detected in parasitised immatures of C. pyri, but likely came from a hymenopteran parasitoid. To obtain insights into natural Wolbachia infection dynamics, we quantified Wolbachia in psyllid individuals from the locality with the highest prevalence across an entire year, spanning several seasonal generations of the host. All tested females were infected and Wolbachia density remained stable across the entire period, suggesting a highly efficient vertical transmission and little influence from the environment and different host generations. In contrast, we observed a tendency towards reduced Wolbachia density in males which may suggest sex-related differences in Wolbachia-psyllid interactions.

• MeSH
• fylogeneze MeSH
• Hemiptera * genetika   MeSH
• Pyrus * MeSH
• roční období MeSH
• Wolbachia * genetika   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH