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Streptococcus mitis: walking the line between commensalism and pathogenesis. Mitchell J Molecular oral microbiology Streptococcus mitis is a viridans streptococcus and a normal commensal of the human oropharynx. However, S. mitis can escape from this niche and cause a variety of infectious complications including infective endocarditis, bacteraemia and septicaemia. It uses a variety of strategies to effectively colonize the human oropharynx. These include expression of adhesins, immunoglobulin A proteases and toxins, and modulation of the host immune system. These various colonization factors allow S. mitis to compete for space and nutrients in the face of its more pathogenic oropharyngeal microbial neighbours. However, it is likely that in vulnerable immune-compromised patients S. mitis will use the same colonization and immune modulation factors as virulence factors promoting its opportunistic pathogenesis. The recent publication of a complete genome sequence for S. mitis strain B6 will allow researchers to thoroughly investigate which genes are involved in S. mitis host colonization and pathogenesis. Moreover, it will help to give insight into where S. mitis fits in the complicated oral microbiome. This review will discuss the current knowledge of S. mitis factors involved in host colonization, their potential role in virulence and what needs to be done to fully understand how a an oral commensal successfully transitions to a virulent pathogen. 10.1111/j.2041-1014.2010.00601.x
as a New Emerging Pathogen in Pediatric Age: Case Report and Systematic Review. Antibiotics (Basel, Switzerland) , a normal inhabitant of the oral cavity, is a member of Viridans Group Streptococci (VGS). Generally recognized as a causative agent of invasive diseases in immunocompromised patients, is considered to have low pathogenic potential in immunocompetent individuals. We present a rare case of sinusitis complicated by meningitis and cerebral sino-venous thrombosis (CSVT) caused by in a previously healthy 12-year-old boy with poor oral health status. With the aim of understanding the real pathogenic role of this microorganism, an extensive review of the literature about invasive diseases due to in pediatric patients was performed. Our data define the critical role of this microorganism in invasive infections, especially in immunocompetent children and in the presence of apparently harmful conditions such as sinusitis and caries. Attention should be paid to the choice of therapy because of VGS's emerging antimicrobial resistance patterns. 10.3390/antibiotics12071222
Antimicrobial resistance patterns and bacterial profiling among dental caries patients. JPMA. The Journal of the Pakistan Medical Association Objectives:To examine the prevalence of dental caries and their antibiotic resistance patterns. METHODS:The cohort study was conducted at the Centre for Advanced Studies in Vaccinology and Biotechnology, University of Balochistan, Quetta, Pakistan, from November 2022 to April 2023, and comprised bacterial dental caries samples that were processed for different biochemical parameters and antibiotic susceptibility. Data was analysed using SPSS version 2022. RESULTS:Out of the 1,000 subjects from whom the samples were collected, 676(67.6%) were males and 324(32.4%) were females. Overall, 426(42.6%) subjects were aged 5-20 years. Of the total samples, 540(54%) were positive for pathogenic bacteria, with streptococcus mutans 256(25.6%) being the most common bacteria, followed by streptococcus mitis 194(19.4%), escherichia coli 69(6.9%) and pseudomonas aeruginosa 21(2.1%). Dental caries was more common among male patients 396 (73.3%), and the most affected age group was 5-20 years 261(48.3%). Illiterate patients 302 (56%) had more dental caries compared to the literate 238 (44.07%) patients. Antibiotic sensitivity tests revealed that most bacterial isolates were highly resistant to ampicillin, ciprofloxacin, and vancomycin. CONCLUSIONS:Dental caries mostly affected males and those aged 5-20 years. Most bacterial isolates were resistant to ampicilin, ciprofloxacin and vancomycin. 10.47391/JPMA.11229
[Identification and antibiotic susceptibility of viridans group streptococci isolates recovered from patients hospitalized at a teaching hospital in Buenos Aires City]. Heine Adriana C,García Susana,Barberis Claudia,Vay Carlos,E Mollerach Marta,Bonofiglio Laura,Famiglietti Ángela Revista Argentina de microbiologia Members of the viridans group streptococci (VGS) are the cause of local and invasive infections. Due to the severity of these infections and taking into account that reports regarding epidemiological aspects are scarce, the aims of this work were the identification and the study of the antibiotic susceptibility profiles of the isolates recovered from patients that were hospitalized in order to find out about the resistance level and the epidemiology of infections in which VGS are involved. A hundred and thirty two isolates identified as VGS were isolated at Hospital de Clínicas «José de San Martín» during the period 2011-2015. The identification was performed by biochemical test and mass spectrometry by Matrix Assisted Laser Desorption Ionization -Time of Flight Mass Spectrometry. Streptococcus anginosus group was prevalent (42%) followed by Streptococcus mitis group (33%). In the latter, isolates of Streptococcus pneumoniae were excluded. All the VGS isolates were susceptible to ertapenem, meropenem, linezolid and vancomycin; 25.8% were resistant (I+R) to penicillin, being prevalent in the S. mitis group. Regarding ceftriaxone and cefepime 96.9% of the isolates were susceptible. Only two isolates were resistant to levofloxacin, 27.2% to tetracycline and it was not found high level resistance to gentamycin (MIC range 0.5-32μg/ml). Resistance to erythromycin was 17.4% with no significant difference between M and MLS phenotypes. The most active antibiotics were in addition to ceftriaxone and cefepime, vancomycin, ertapenem, meropenem and linezolid. These results highlight the importance of the continuous surveillance of the infections caused by VGS in order to predict a correct antibiotic therapy. 10.1016/j.ram.2018.03.004
Epidemiological analysis of pneumococcal strains isolated at Yangon Children's Hospital in Myanmar via whole-genome sequencing-based methods. Microbial genomics causes over one million deaths from lower respiratory infections per annum worldwide. Although mortality is very high in Southeast Asian countries, molecular epidemiological information remains unavailable for some countries. In this study, we report, for the first time, the whole-genome sequences and genetic profiles of pneumococcal strains isolated in Myanmar. We isolated 60 streptococcal strains from 300 children with acute respiratory infection at Yangon Children's Hospital in Myanmar. We obtained whole-genome sequences and identified the species, serotypes, sequence types, antimicrobial resistance (AMR) profiles, virulence factor profiles and pangenome structure using sequencing-based analysis. Average nucleotide identity analysis indicated that 58 strains were and the other 2 strains were . The major serotype was 19F (11 strains), followed by 6E (6B genetic variant; 7 strains) and 15 other serotypes; 5 untypable strains were also detected. Multilocus sequence typing analysis revealed 39 different sequence types, including 11 novel ones. In addition, genetic profiling indicated that AMR genes and mutations spread among pneumococcal strains in Myanmar. A minimum inhibitory concentration assay indicated that several pneumococcal strains had acquired azithromycin and tetracycline resistance, whereas no strains were found to be resistant against levofloxacin and high-dose penicillin G. Phylogenetic and pangenome analysis showed various pneumococcal lineages and that the pneumococcal strains contain a rich and mobile gene pool, providing them with the ability to adapt to selective pressures. This molecular epidemiological information can help in tracking global infection and supporting AMR control in addition to public health interventions in Myanmar. 10.1099/mgen.0.000523
Third-generation cephalosporin and carbapenem resistance in Streptococcus mitis/oralis. Results from a nationwide registry in the Netherlands. van Prehn J,van Triest M I,Altorf-van der Kuil W,van Dijk K, Clinical microbiology and infection : the official publication of the European Society of Clinical Microbiology and Infectious Diseases 10.1016/j.cmi.2018.11.021
Novel Multilocus Sequence Typing and Global Sequence Clustering Schemes for Characterizing the Population Diversity of Streptococcus mitis. Journal of clinical microbiology Streptococcus mitis is a common oral commensal and an opportunistic pathogen that causes bacteremia and infective endocarditis; however, the species has received little attention compared to other pathogenic streptococcal species. Effective and easy-to-use molecular typing tools are essential for understanding bacterial population diversity and biology, but schemes specific for S. mitis are not currently available. We therefore developed a multilocus sequence typing (MLST) scheme and defined sequence clusters or lineages of S. mitis using a comprehensive global data set of 322 genomes (148 publicly available and 174 newly sequenced). We used internal 450-bp sequence fragments of seven housekeeping genes (, , , , , , and ) to define the MLST scheme and derived the global S. mitis sequence clusters using the PopPUNK clustering algorithm. We identified an initial set of 259 sequence types (STs) and 258 global sequence clusters. The schemes showed high concordance (100%), capturing extensive S. mitis diversity with strains assigned to multiple unique STs and global sequence clusters. The tools also identified extensive within- and between-host S. mitis genetic diversity among isolates sampled from a cohort of healthy individuals, together with potential transmission events, supported by both phylogeny and pairwise single nucleotide polymorphism (SNP) distances. Our novel molecular typing and strain clustering schemes for S. mitis allow for the integration of new strain data, are electronically portable at the PubMLST database (https://pubmlst.org/smitis), and offer a standardized approach to understanding the population structure of S. mitis. These robust tools will enable new insights into the epidemiology of S. mitis colonization, disease and transmission. 10.1128/jcm.00802-22