-
MBio 2012Transformation of genetic material between bacteria was first observed in the 1920s using Streptococcus pneumoniae as a model organism. Since then, the mechanism of...
UNLABELLED
Transformation of genetic material between bacteria was first observed in the 1920s using Streptococcus pneumoniae as a model organism. Since then, the mechanism of competence induction and transformation has been well characterized, mainly using planktonic bacteria or septic infection models. However, epidemiological evidence suggests that genetic exchange occurs primarily during pneumococcal nasopharyngeal carriage, which we have recently shown is associated with biofilm growth, and is associated with cocolonization with multiple strains. However, no studies to date have comprehensively investigated genetic exchange during cocolonization in vitro and in vivo or the role of the nasopharyngeal environment in these processes. In this study, we show that genetic exchange during dual-strain carriage in vivo is extremely efficient (10(-2)) and approximately 10,000,000-fold higher than that measured during septic infection (10(-9)). This high transformation efficiency was associated with environmental conditions exclusive to the nasopharynx, including the lower temperature of the nasopharynx (32 to 34°C), limited nutrient availability, and interactions with epithelial cells, which were modeled in a novel biofilm model in vitro that showed similarly high transformation efficiencies. The nasopharyngeal environmental factors, combined, were critical for biofilm formation and induced constitutive upregulation of competence genes and downregulation of capsule that promoted transformation. In addition, we show that dual-strain carriage in vivo and biofilms formed in vitro can be transformed during colonization to increase their pneumococcal fitness and also, importantly, that bacteria with lower colonization ability can be protected by strains with higher colonization efficiency, a process unrelated to genetic exchange.
IMPORTANCE
Although genetic exchange between pneumococcal strains is known to occur primarily during colonization of the nasopharynx and colonization is associated with biofilm growth, this is the first study to comprehensively investigate transformation in this environment and to analyze the role of environmental and bacterial factors in this process. We show that transformation efficiency during cocolonization by multiple strains is very high (around 10(-2)). Furthermore, we provide novel evidence that specific aspects of the nasopharyngeal environment, including lower temperature, limited nutrient availability, and epithelial cell interaction, are critical for optimal biofilm formation and transformation efficiency and result in bacterial protein expression changes that promote transformation and fitness of colonization-deficient strains. The results suggest that cocolonization in biofilm communities may have important clinical consequences by facilitating the spread of antibiotic resistance and enabling serotype switching and vaccine escape as well as protecting and retaining poorly colonizing strains in the pneumococcal strain pool.
Topics: Animals; Bacterial Capsules; Biofilms; Carrier State; DNA Transformation Competence; Female; Mice; Mice, Inbred BALB C; Nasopharynx; Pneumococcal Infections; Recombination, Genetic; Streptococcus pneumoniae; Transformation, Bacterial
PubMed: 23015736
DOI: 10.1128/mBio.00200-12 -
Microbiology (Reading, England) Feb 2006Pneumococci display large zinc metalloproteinases on the surface, including the IgA protease, which cleaves human IgA1 in the hinge region, the ZmpC proteinase, which...
Pneumococci display large zinc metalloproteinases on the surface, including the IgA protease, which cleaves human IgA1 in the hinge region, the ZmpC proteinase, which cleaves human matrix metalloproteinase 9 (MMP-9), and two other proteinases, ZmpB and ZmpD, whose substrates have not yet been identified. Surface metalloproteinases are antigenic and have been linked to virulence. The genes encoding these proteinases reside in three distinct loci: two loci specific for zmpB and zmpC, and a third, the iga locus, containing iga and zmpD. Data obtained by this and other groups have shown that pneumococcal metalloproteinase genes are transcribed and yield mature and enzymatically active proteins. Since the presence of the four proteinase genes is variable in the pneumococcal strains whose genomes have been sequenced, the presence of these genes in a collection of 218 pneumococcal isolates, mostly from invasive disease, was investigated. The data showed that zmpB and iga were present in all the isolates examined, while zmpC and zmpD were present in a variable proportion of the isolates (in 18 and 49 %, respectively). Interestingly, isolates carrying both zmpC and zmpD were found to belong mainly to two serotypes (sts), 8 and 11A. By molecular typing, st 8 and st 11A isolates appeared to belong to the same clonal cluster. The presence of these two additional metalloproteinases could contribute to the fitness of particular pneumococcal clones.
Topics: Animals; Bacterial Typing Techniques; Metalloproteases; Pneumococcal Infections; Serotyping; Streptococcus pneumoniae; Zinc
PubMed: 16436419
DOI: 10.1099/mic.0.28417-0 -
Antimicrobial Agents and Chemotherapy Oct 2005Macrolide resistance in Streptococcus pneumoniae due to efflux has emerged as an important worldwide clinical problem over the past decade. Efflux is mediated by the... (Comparative Study)
Comparative Study
Macrolide resistance in Streptococcus pneumoniae due to efflux has emerged as an important worldwide clinical problem over the past decade. Efflux is mediated by the genes of the genetic element mega (macrolide efflux genetic assembly) and related elements, such as Tn1207.1. These elements contain two adjacent genes, mef (mefE or mefA) and the closely related mel gene (msrA homolog), encoding a proton motive force pump and a putative ATP-binding cassette transporter homolog, and are transcribed as an operon (M. Del Grosso et al., J. Clin. Microbiol. 40:774-778, 2004; K. Gay and D. S. Stephens, J. Infect. Dis. 184:56-65, 2001; and M. Santagati et al., Antimicrob. Agents Chemother. 44:2585-2587, 2000). Previous studies have shown that Mef is required for macrolide resistance in S. pneumoniae; however, the contribution of Mel has not been fully determined. Independent deletions were constructed in mefE and mel in the serotype 14 macrolide-resistant strains GA16638 (erythromycin [Em] MIC, 8 to 16 microg/ml) and GA17719 (Em MIC, 2 to 4 microg/ml), which contain allelic variations in the mega element. The MICs to erythromycin were significantly reduced for the independent deletion mutants of both mefE and mel compared to those of the parent strains and further reduced threefold to fourfold to Em MICs of <0.15 microg/ml with mefE mel double mutants. Using quantitative reverse transcription-PCR, the expression of mefE in the mel deletion mutants was increased more than 10-fold. However, in the mefE deletion mutants, the expression of mel did not differ significantly from the parent strains. The expression of both mefE and mel was inducible by erythromycin. These data indicate a requirement for both Mef and Mel in the novel efflux-mediated macrolide resistance system in S. pneumoniae and other gram-positive bacteria and that the system is inducible by macrolides.
Topics: Bacterial Proteins; Drug Resistance, Bacterial; Erythromycin; Gene Deletion; Genes, Bacterial; Macrolides; Reverse Transcriptase Polymerase Chain Reaction; Serotyping; Streptococcus pneumoniae
PubMed: 16189099
DOI: 10.1128/AAC.49.10.4203-4209.2005 -
Genome Biology and Evolution Apr 2016Streptococcus pneumoniae is a major cause of meningitis, sepsis, and pneumonia worldwide. Pneumococcal conjugate vaccines have been part of the United Kingdom's... (Comparative Study)
Comparative Study
Streptococcus pneumoniae is a major cause of meningitis, sepsis, and pneumonia worldwide. Pneumococcal conjugate vaccines have been part of the United Kingdom's childhood immunization program since 2006 and have significantly reduced the incidence of disease due to vaccine efficacy in reducing carriage in the population. Here we isolated two clones of 22F (an emerging serotype of clinical concern, multilocus sequence types 433 and 698) and conducted comparative genomic analysis on four isolates, paired by Sequence Type (ST) with one of each pair being derived from carriage and the other disease (sepsis). The most compelling observation was of nonsynonymous mutations in pgdA, encoding peptidoglycan N-acetylglucosamine deacetylase A, which was found in the carriage isolates of both ST433 and 698. Deacetylation of pneumococcal peptidoglycan is known to enable resistance to lysozyme upon invasion. Althought no other clear genotypic signatures related to disease or carriage could be determined, additional intriguing comparisons between the two STs were possible. These include the presence of an intact prophage, in addition to numerous additional phage insertions, within the carriage isolate of ST433. Contrasting gene repertoires related to virulence and colonization, including bacteriocins, lantibiotics, and toxin--antitoxin systems, were also observed.
Topics: Amidohydrolases; Anti-Bacterial Agents; Bacterial Proteins; Child; Drug Resistance, Microbial; Female; Genome, Bacterial; Genomic Islands; Genomics; Humans; Male; Middle Aged; Mutation; Pneumococcal Infections; Streptococcus pneumoniae; Virulence Factors
PubMed: 27016484
DOI: 10.1093/gbe/evw066 -
International Journal of Infectious... Mar 2021Streptococcus pneumoniae (S. pneumoniae) of serogroup 19 are mainly represented by serotypes 19A and 19F, which are associated with antimicrobial resistance and disease....
Characterization of Streptococcus pneumoniae serotype 19F-variants occurring in Brazil uncovers a predominant lineage that can lead to misinterpretation in capsular typing.
BACKGROUND
Streptococcus pneumoniae (S. pneumoniae) of serogroup 19 are mainly represented by serotypes 19A and 19F, which are associated with antimicrobial resistance and disease. The wzy gene, a component of the pneumococcal capsular locus, is the target to differentiate serotypes 19A and 19F by PCR-based capsular typing. In the last decade, allelic variants of the wzy gene have been described, leading to misinterpretation of capsular typing results.
METHODS
A collection of 154 serotype 19F S. pneumoniae strains recovered from carriage and disease in Brazil was evaluated to identify and characterize wzy variant isolates.
RESULTS
Eleven (7%) wzy variant isolates were detected and identified as belonging to ST810 (n = 10) or ST13673 (n = 1; single-locus variant of ST810). They were mostly recovered from diseased patients, susceptible to the antimicrobial agents tested (except for one multidrug-resistant strain) and did not harbor pili genes. Sequences of the wzy gene of these variants were identical to each other and to those previously described in Brazil, but slightly different from wzy variants identified in other countries.
CONCLUSION
This study indicated that wzy variants present a geographically driven distribution and was the first to uncover phenotypic and genetic features of a wzy variant lineage occurring in Brazil since 1989.
Topics: Alleles; Asymptomatic Infections; Bacterial Capsules; Brazil; Carrier Proteins; Carrier State; Female; Genetic Variation; Humans; Male; Multilocus Sequence Typing; Pneumococcal Infections; Polymerase Chain Reaction; Serogroup; Serotyping; Streptococcus pneumoniae
PubMed: 33476756
DOI: 10.1016/j.ijid.2021.01.030 -
Antimicrobial Agents and Chemotherapy May 2019Two whole-genome screening approaches are described for studying the mode of action and the mechanisms of resistance to trimethoprim (TMP) in the Gram-positive The...
Two whole-genome screening approaches are described for studying the mode of action and the mechanisms of resistance to trimethoprim (TMP) in the Gram-positive The gain-of-function approach (Int-Seq) relies on a genomic library of DNA fragments integrated into a fucose-inducible cassette. The second approach, leading to both gain- and loss-of-function mutation, is based on chemical mutagenesis coupled to next-generation sequencing (Mut-Seq). Both approaches pointed at the drug target dihydrofolate reductase (DHFR) as a major resistance mechanism to TMP. Resistance was achieved by overexpression either through the addition of fucose (Int-Seq) or by mutations upstream of the gene (Mut-Seq). Three types of mutations increased expression by disrupting a predicted Rho-independent terminator upstream of Known and novel DHFR mutations were also detected by Mut-Seq, and these were functionally validated for TMP resistance. The two approaches also suggested that an increase in the metabolic flux from purine synthesis to GTP and then to folate can modulate the susceptibility to TMP. Finally, we provide evidence for a novel role of the ABC transporter PatAB in TMP susceptibility. Our genomic screens highlighted novel aspects on the mode of action and mechanisms of resistance to antibiotics.
Topics: Anti-Bacterial Agents; Drug Resistance, Bacterial; High-Throughput Nucleotide Sequencing; Mutation; Streptococcus pneumoniae; Trimethoprim
PubMed: 30783004
DOI: 10.1128/AAC.02381-18 -
Molecular Microbiology Jul 2010The genome of Streptococcus pneumoniae strains, as typified by the TIGR4 strain, contain several genes encoding proteins putatively involved in alpha-glucan degradation,...
The genome of Streptococcus pneumoniae strains, as typified by the TIGR4 strain, contain several genes encoding proteins putatively involved in alpha-glucan degradation, modification and synthesis. The extracellular components comprise an ATP binding cassette-transporter with its solute binding protein, MalX, and the hydrolytic enzyme SpuA. We show that of the commonly occurring exogenous alpha-glucans, S. pneumoniae TIGR4 is only able to grow on glycogen in a MalX- and SpuA-dependent manner. SpuA is able to degrade glycogen into a ladder of alpha-1,4-glucooligosaccharides while the high-affinity interaction (K(a) approximately 10(6) M(-1)) of MalX with maltooligosaccharides plays a key role in promoting the selective uptake of the glycogen degradation products that are produced by SpuA. The X-ray crystallographic analyses of apo- and complexed MalX illuminate the protein's specificity for the degradation products of glycogen and its striking ability to recognize the helical structure of the ligand. Overall, the results of this work provide new structural and functional insight into streptococcal alpha-glucan metabolism while supplying biochemical support for the hypothesis that the substrate of the S. pneumoniaealpha-glucan metabolizing machinery is glycogen, which in a human host is abundant in lung epithelial cells, a common target for invasive S. pneumoniae.
Topics: Bacterial Proteins; Crystallography, X-Ray; Glycogen; Membrane Transport Proteins; Metabolic Networks and Pathways; Models, Molecular; Multigene Family; Oligosaccharides; Protein Structure, Tertiary; Streptococcus pneumoniae
PubMed: 20497336
DOI: 10.1111/j.1365-2958.2010.07199.x -
Canadian Journal of Microbiology Jun 2024is the major cause of invasive pneumococcal disease. However, the global population structure remains largely unexplored. In this study, we investigated the spatial and...
is the major cause of invasive pneumococcal disease. However, the global population structure remains largely unexplored. In this study, we investigated the spatial and temporal patterns of genetic variation of . based on archived multilocus sequence typing data from PubMLST.org. Our analyses demonstrated both shared and unique distributions of sequence types (STs) and allele types among regional populations. Among the 17 915 global STs, 36 representing 15 263 isolates were broadly shared among all six continents, consistent with recent clonal dispersal and expansion of this pathogen. The analysis of molecular variance revealed that >96% genetic variations were found within individual regional populations. However, though low (<4%), statistically significant genetic differentiation among regional populations was observed. Comparisons between non-clone-corrected and clone-corrected datasets showed that localized clonal expansion contributed significantly to the observed genetic differentiations among regions. Temporal analyses of the isolates showed that implementation of pneumococcal conjugate vaccine impacted the distributions of STs, but the effect on population structure was relatively limited. Linkage disequilibrium analyses identified evidence for recombination in all continental populations; however, the inferred recombination was not random. We discussed the limitations and implications of our analyses to the global epidemiology and future vaccine developments for .
Topics: Streptococcus pneumoniae; Pneumococcal Infections; Humans; Genetic Variation; Multilocus Sequence Typing; Linkage Disequilibrium; Recombination, Genetic; Global Health; Spatio-Temporal Analysis
PubMed: 38422492
DOI: 10.1139/cjm-2023-0155 -
Journal of Clinical Microbiology Jun 2013Discrimination between Streptococcus pneumoniae and its close relatives of the viridans group is a common difficulty in matrix-assisted laser desorption ionization-time...
Identification of clinical Streptococcus pneumoniae isolates among other alpha and nonhemolytic streptococci by use of the Vitek MS matrix-assisted laser desorption ionization-time of flight mass spectrometry system.
Discrimination between Streptococcus pneumoniae and its close relatives of the viridans group is a common difficulty in matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry-based identification. In the present study, the performances of the Vitek MS MALDI-TOF mass spectrometry system were assessed using 334 pneumococci, 166 other S. mitis group streptococci, 184 non-S. mitis group streptococci, and 19 related alpha- and nonhemolytic aerobic Gram-positive catalase-negative coccal isolates. Pneumococci had been identified by means of optochin susceptibility and bile solubility or serotyping, and other isolates mainly by use of RapidID32 Strep strips. In case of discordant or low-discrimination results, genotypic methods were used. The sensitivity of the Vitek MS for the identification of S. pneumoniae was 99.1%, since only three bile-insoluble isolates were misidentified as Streptococcus mitis/Streptococcus oralis. Conversely, two optochin-resistant pneumococci were correctly identified (specificity, 100%). Three Streptococcus pseudopneumoniae isolates were also correctly identified. Among nonpneumococcal isolates, 90.8% (n = 335) were correctly identified to the species or subspecies level and 2.4% (n = 9) at the group level. For the remaining 25 isolates, the Vitek MS proposed a bacterial species included in the list of possible species suggested by genotypic methods, except for 4 isolates which were not identified due to the absence of the species in the database. According to our study, the Vitek MS displays performance similar to that of the optochin susceptibility test for routine identification of pneumococcal isolates. Moreover, the Vitek MS is efficient for the identification of other viridans group streptococci and related isolates, provided that the species are included in the database.
Topics: Anti-Bacterial Agents; Bacteriological Techniques; DNA, Bacterial; Humans; Molecular Sequence Data; Pneumococcal Infections; Quinine; Sensitivity and Specificity; Sequence Analysis, DNA; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Streptococcus pneumoniae
PubMed: 23576536
DOI: 10.1128/JCM.03069-12 -
Brazilian Journal of Microbiology :... 2018This study examined the antimicrobial susceptibility patterns and clonal complex (CC) characteristics of serogroup 6 Streptococcus pneumoniae isolates collected from...
Antimicrobial susceptibility and fluctuations in clonal complexes of serogroup 6 Streptococcus pneumoniae isolates collected from children in Beijing, China, between 1997 and 2016.
This study examined the antimicrobial susceptibility patterns and clonal complex (CC) characteristics of serogroup 6 Streptococcus pneumoniae isolates collected from children in Beijing, China, between 1997 and 2016. Serotypes were determined using the Quellung reaction, and the antimicrobial susceptibility profiles of the isolates were determined using the disc-diffusion method or by E-test. Sequence types (STs) were assigned based on multilocus sequence typing. A total of 250 isolates were examined, with 55.2%, 30.0%, 12.8%, and 2.0% of isolates identified as serotypes 6A, 6B, 6C, and 6D, respectively. All of the isolates were susceptible to levofloxacin and vancomycin, and the non-suceptibitility rate to penicillin was 41.6%. Eighty-two distinct STs, assigned to 13 CCs and 28 singletons, were identified. CC982 was the most prevalent CC amongst serotype 6A isolates (34%), followed by CC9789 and CC3173. Amongst serotype 6B isolates, CC90 and CC4542 were the most common, accounting for 25.3% and 14.7% of isolates respectively. Over the study period, the prevalence of CC982, CC4542, and CC4536 isolates showing susceptibility to penicillin and cefuroxime decreased, and the proportion of CC3173, CC9789, CC855, and CC902 isolates showing non-susceptibility to these two antibiotics increased.
Topics: Anti-Bacterial Agents; Beijing; Child; Child, Preschool; China; Female; Humans; Male; Microbial Sensitivity Tests; Multilocus Sequence Typing; Penicillins; Phylogeny; Pneumococcal Infections; Streptococcus pneumoniae
PubMed: 29606509
DOI: 10.1016/j.bjm.2018.02.004