Clinical and laboratory features of Streptococcus salivarius meningitis: a case report and literature review

Isolation of phages against Streptococcus species in the oral cavity for potential control of dental diseases and associated systemic complications

Dental infections and systemic complications caused by Streptococcus species in the oral cavity are increasingly exhibiting resistance to commonly used antibiotics, posing a potential threat to global public health. Phage therapy may offer a superior alternative, given that bacteriophages can be easily isolated and rapidly replicate in large numbers. In this study, six Streptococcus species from the oral cavity were characterized. Bacteriophages isolated from wastewater using five of these species as hosts produced plaques ranging from 0.2 to 2.4 mm in size. The phages demonstrated stability within a temperature range of 4 ℃ to 37 ℃. However, at temperatures exceeding 45 ℃, a noticeable reduction in bacteriophage titer was observed. Similarly, the phages showed greater stability within a pH range of 5 to 10. The isolated phages exhibited latency periods ranging from 15 to 20 min and had burst sizes varying from 10 to 200 viral particles. This study supports the potential use of bacteriophages in controlling infections caused by Streptococcus species.

Noniatrogenic Meningitis Caused by Streptococcus salivarius Associated with Early Esophageal Cancer and Early Gastric Cancer

Streptococcus salivarius is part of the normal oral cavity and gastrointestinal tract microflora and an unusual cause of acute bacterial meningitis. We herein report an 81-year-old man with S. salivarius meningitis, which led to a diagnosis of early esophageal cancer and early gastric cancer. S. salivarius infection may occur through the gastrointestinal mucosa when it is disrupted in association with early gastrointestinal cancer. To our knowledge, this is the first report describing S. salivarius meningitis associated with multiple early gastrointestinal cancers in the absence of other sources of infection.

Cell wall polysaccharides of streptococci: A genetic and structural perspective

The Streptococcus genus comprises both commensal and pathogenic species. Additionally, Streptococcus thermophilus is exploited in fermented foods and in probiotic preparations. The ecological and metabolic diversity of members of this genus is matched by the complex range of cell wall polysaccharides that they present on their cell surfaces. These glycopolymers facilitate their interactions and environmental adaptation. Here, current knowledge on the genetic and compositional diversity of streptococcal cell wall polysaccharides including rhamnose-glucose polysaccharides, exopolysaccharides and teichoic acids is discussed. Furthermore, the species-specific cell wall polysaccharide combinations and specifically highlighting the presence of rhamnose-glucose polysaccharides in certain species, which are replaced by teichoic acids in other species. This review highlights model pathogenic and non-pathogenic species for which there is considerable information regarding cell wall polysaccharide composition, structure and genetic information. These serve as foundations to predict and focus research efforts in other streptococcal species for which such data currently does not exist.

Impact of waterpipe smoking on the salivary microbiome

Background

While oral mirobial dysbiosis due to tobacco smoking has been studied thoroughly, there is limited data on the effect of waterpipe smoking on the oral microbiome. This study aims to compare the salivary microbiome between waterpipe smokers and non-smokers.

Materials and methods

Unstimulated saliva samples were collected from 60 participants, 30 smokers and 30 non-smokers in Kuala Lumpur and Klang Valley, Malaysia. DNA extraction was performed using the Qiagen DNA mini kit, and the 16S rRNA bacterial gene was amplified and sequenced using the Illumina MiSeq platform. Sequencing reads were processed using DADA2, and the alpha and beta diversity of the bacterial community was assessed. Significantly differentiated taxa were identified using LEfSe analysis, while differentially expressed pathways were identified using MaAsLin2.

Results

A significant compositional change (beta diversity) was detected between the two groups (PERMANOVA P < 0.05). Specifically, the levels of phylum Firmicutes and genus Streptococcus were elevated in smokers, whereas phylum Proteobacteria and genus Haemophilus were depleted compared to non-smokers. At the species level, Streptococcus oralis, Streptococcus salivarius, and Streptococcus gingivalis were enriched in smokers. We observed significant differences in the abundance of thirty-seven microbial metabolic pathways between waterpipe smokers and non-smokers. The microbial pathways enriched in smokers were those implicated in polymer degradation and amino acid metabolism.

Conclusion

The taxonomic and metabolic profile of the salivary microbiome in waterpipe smokers compared to healthy controls exhibited a paradigm shift, thus, implying an alteration in the homeostatic balance of the oral cavity posing unique challenges for oral health.

Exacerbation of allergic rhinitis by the commensal bacterium Streptococcus salivarius

Allergic rhinitis (AR)-commonly called hay fever-is a widespread condition that affects the quality of life of millions of people. The pathophysiology of AR remains incompletely understood. In particular, it is unclear whether members of the colonizing nasal microbiota contribute to AR. Here, using 16S ribosomal RNA sequencing, we show that the nasal microbiome of patients with AR (n = 55) shows distinct differences compared with that from healthy individuals (n = 105), including decreased heterogeneity and the increased abundance of one species, Streptococcus salivarius. Using ex vivo and in vivo models of AR, we demonstrate that this commensal bacterium contributes to AR development, promoting inflammatory cytokine release and morphological changes in the nasal epithelium that are characteristic of AR. Our data indicate that this is due to the ability of S. salivarius to adhere to the nasal epithelium under AR conditions. Our study indicates the potential of targeted antibacterial approaches for AR therapy.

Selection of Beneficial Bacterial Strains With Potential as Oral Probiotic Candidates

This study aimed to select beneficial strains from the oral cavity of healthy volunteers and to evaluate these as potential oral probiotic candidates. The selection process was based on the isolation, differentiation, identification, and safety assessment of LAB strains, followed by a series of experiments for the selection of appropriate candidates with beneficial properties. In the screening procedure, 8 isolates from the oral cavity of a Caucasian volunteers were identified as Streptococcus (Str.) salivarius ST48HK, ST59HK, ST61HK, and ST62HK; Lactiplantibacillus plantarum (Lb.) (Lactobacillus plantarum) ST63HK and ST66HK; Latilactobacillus sakei (Lb.) (Lactobacillus sakei) ST69HK; and Lactobacillus (Lb.) gasseri ST16HK based on 16S rRNA sequencing. Physiological and phenotypic tests did not show hemolytic, proteinase, or gelatinase activities, as well as production of biogenic amines. In addition, screening for the presence of efaA, cyt, IS16, esp, asa1, and hyl virulence genes and vancomycin-resistant genes confirmed safety of the studied strains. Moreover, cell-to-cell antagonism indicated that the strains were able to inhibit the growth of tested representatives from the genera Bacillus, Enterococcus, Streptococcus, and Staphylococcus in a strain-specific manner. Various beneficial genes were detected including gad gene, which codes for GABA production. Furthermore, cell surface hydrophobicity levels ranging between 1.58% and 85% were determined. The studied strains have also demonstrated high survivability in a broad range of pH (4.0-8.0). The interaction of the 8 putative probiotic candidates with drugs from different groups and oral hygiene products were evaluated for their MICs. This is to determine if the application of these drugs and hygiene products can negatively affect the oral probiotic candidates. Overall, antagonistic properties, safety assessment, and high rates of survival in the presence of these commonly used drugs and oral hygiene products indicate Str. salivarius ST48HK, ST59HK, ST61HK, and ST62HK; Lb. plantarum ST63HK and ST66HK; Lb. sakei ST69HK; and Lb. gasseri ST16HK as promising oral cavity probiotic candidates.

Bacterial meningitis without pyrexia after spinal anesthasia for caesarean section: A case report

Introduction and importancy

Meningitis happening in post spinal anesthesia is rare. But it has potentially life threatening or permanent neurological sequel if delayed or left untreated. The cause can be infectious or noninfectious. In this case, uncommon pathogen is described causing bacterial meningitis. Incidence varies from 0% to 0.04%.

Case presentation

A term pregnant lady came to the Operation room (OR) for an emergency caesarian section(C/S) because of cervical dystocia. She has no history of known medical illness. The anesthetist planned to administer spinal anesthesia. Under aseptic technique, the senior anesthetist wore a tight-fitting surgical mask, cap, and sterile gloves after hand hygiene with alcohol-based solutions.

In sitting positioning between L(lumbar) 3 and L4 interspaces 10 mg bupivacaine +10 μg fentanyl was administered. Surgery and anesthesia were uneventful, 16 h into the postoperative period the mother develop severe headache, agitation, confusion, and forgetfulness.

She has no fever but meningeal sign was positive. Lumbar puncture (LP) reveals purulent cerebrospinal fluid (CSF).

Immediately, empirical treatment began. CSF sent for analysis and Culture, hematology, urinalysis, and organ function tests requested. Diagnosis was confirmed by clinical picture, low CSF glucose, and high body fluid protein, culture growth; showed Escherichia coli (E.coli). Treatment was instituted and patient has recovered fully.

Clinical discussion

E.coli is a very rare cause of bacterial meningitis but manifests a similar clinical picture like other bacterial meningitis but in our case no pyrexia. We believe there is a sterility breach somewhere in the process. The use of hospital sterilized spinal set, multidose antiseptics; institute sterility practice might be challenged.

Conclusion

The use of modern packaging is recommended. Despite absent of pyrexia empiric treatment must start earlier besides the application of national guideline developed by the Joint Commission of different associations including America society of regional anesthesia (ASRA) is recommended.

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Bacterial meningitis post spinal anesthesia is rare but can result life threatening complication.

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In this case, uncommon pathogen e.coli1 is causing bacterial meningitis .as to me no reported cases (obstetric and non-obstetric ) e.coli bacteria as causative agent in PDPBM 2.most clinical picture of bacterial meningitis reveled but in our case no pyrexia .

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Immediately after LP3 which appears purulent Empirical therapy began resulting in full recovery, no long term neurological sequel.

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It raises questions regarding the use of locally sterilized spinal pack, wearing of sterile gown &adherence in check list in order to prevent contamination of both the site of LP and the equipment used

Identification of microbial agents in tissue specimens of ocular and periocular sarcoidosis using a metagenomics approach

Background: Metagenomic sequencing has the potential to identify a wide range of pathogens in human tissue samples. Sarcoidosis is a complex disorder whose etiology remains unknown and for which a variety of infectious causes have been hypothesized. We sought to conduct metagenomic sequencing on cases of ocular and periocular sarcoidosis, none of them with previously identified infectious causes. Methods: Archival tissue specimens of 16 subjects with biopsies of ocular and periocular tissues that were positive for non-caseating granulomas were used as cases. Four archival tissue specimens that did not demonstrate non-caseating granulomas were also included as controls. Genomic DNA was extracted from tissue sections. DNA libraries were generated from the extracted genomic DNA and the libraries underwent next-generation sequencing. Results: We generated between 4.8 and 20.7 million reads for each of the 16 cases plus four control samples. For eight of the cases, we identified microbial pathogens that were present well above the background, with one potential pathogen identified for seven of the cases and two possible pathogens for one of the cases. Five of the eight cases were associated with bacteria ( Campylobacter concisus, Neisseria elongata, Streptococcus salivarius, Pseudopropionibacterium propionicum, and Paracoccus yeei), two cases with fungi ( Exophiala oligosperma, Lomentospora prolificans and Aspergillus versicolor) and one case with a virus (Mupapillomavirus 1). Interestingly, four of the five bacterial species are also part of the human oral microbiome. Conclusions: Using a metagenomic sequencing we identified possible infectious causes in half of the ocular and periocular sarcoidosis cases analyzed. Our findings support the proposition that sarcoidosis could be an etiologically heterogenous disease. Because these are previously banked samples, direct follow-up in the respective patients is impossible, but these results suggest that sequencing may be a valuable tool in better understanding the etiopathogenesis of sarcoidosis and in diagnosing and treating this disease.

Microbial contamination profile change over a 4-year period in nonoperated cleft soft palate

AIMS

Surgical site infection is a major concern in cleft soft palate. Knowledge of the type, number and antimicrobial resistance of pathogens present preoperatively contribute to treatment success. The aim of this study is to determine whether or not the microbial contamination (diversity) preoperatively has changed since 2015.

METHODS AND RESULTS

Swabs were taken from the surgical site in 103 consecutive patients who presented for primary repair of the soft palate cleft. These were sent for microscopy, culture and sensitivity testing. Swabs were taken before disinfecting the site. Results were tabled and compared with two previous studies from the same facility. Out of 103 patients, 100 patients showed positive cultures with 42 different pathogenic micro-organisms identified. Most dominant pathogen was Klebsiella pneumoniae, 45.6%, increased by 28% from the previous two studies, with 93.6% of these pathogens resistant to one or more antimicrobials. Most of the other identified pathogens showed an alarming increase in occurrence, with a wide resistance to antimicrobials.

CONCLUSIONS

The increase in number and diversity of microbial contamination as well as their resistance to antimicrobials is a real concern. Ways of preventing postoperative infection in a natural way need to be explored.

SIGNIFICANCE

Surgeons need to be aware of constant changes in micro-organisms.

Using next-generation sequencing to develop a Shigella species threshold and profile faecal samples from suspected diarrhoea cases

Globally, it is estimated that there are 2 billion cases of diarrhoeal disease each year, with 525,000 children under the age of 5 years, dying from diarrhoea. This also affects 1 in 5 people in the UK each year. Rapid diagnosis, appropriate treatment and infection control measures are, therefore, particularly important. Currently, Public Health Wales and England Microbiology Division test for five key bacterial gastrointestinal pathogens, i.e. Escherichia coli O157 (VTEC), Shigella dysenteriae, Salmonella spp., Campylobacter spp. and Clostridioides difficile. There is, however, a poor success rate with identification of these pathogens, leaving the patient at risk from untreated infections. This study has developed effective and reliable tools with a high positive outcome for diagnosis of diarrhoeal infection. The study blindly analysed 592 samples, with the most abundant species being Shigella sonnei at 15%, and the top genus Bacteroides at 26%. Campylobacter spp. had an abundance of 4%, Clostridium difficile 3%, and Salmonella spp. 0.2%. There were also significant differences in abundance at genus level, between the Flemish Gut project and diarrhoea samples, with respect to Shigella (0.2%) and Campylobacter (0.1%). The project introduced a novel Shigella spp. (Escherichia) threshold of 5.32% to determine (Escherichia) a healthy or unhealthy community. A DMBiome model was developed to integrate the 5.32% threshold of Shigella spp., the Public Health laboratory tested pathogens, and two emerging enteropathogens. The overall positive outcome was that 89% of all samples were diagnosed with diarrhoea infections, leaving 11% unknown.

Abundance, Diversity and Role of ICEs and IMEs in the Adaptation of Streptococcus salivarius to the Environment

Streptococcus salivarius is a significant contributor to the human oral, pharyngeal and gut microbiomes that contribute to the maintenance of health. The high genomic diversity observed in this species is mainly caused by horizontal gene transfer. This work aimed to evaluate the contribution of integrative and conjugative elements (ICEs) and integrative and mobilizable elements (IMEs) in S. salivarius genome diversity. For this purpose, we performed an in-depth analysis of 75 genomes of S. salivarius and searched for signature genes of conjugative and mobilizable elements. This analysis led to the retrieval of 69 ICEs, 165 IMEs and many decayed elements showing their high prevalence in S. salivarius genomes. The identification of almost all ICE and IME boundaries allowed the identification of the genes in which these elements are inserted. Furthermore, the exhaustive analysis of the adaptation genes carried by these elements showed that they encode numerous functions such as resistance to stress, to antibiotics or to toxic compounds, and numerous enzymes involved in diverse cellular metabolic pathways. These data support the idea that not only ICEs but also IMEs and decayed elements play an important role in S. salivarius adaptation to the environment.

[A rare case of Streptococcus salivarius meningitis in elderly]

An 80-year-old man who had chronic heart failure and atrial fibrillation was refered to our hospital because of acute onset of fever and consciousness disturbance. Neurological examinations revealed deteriorated consciousness, nuchal rigidity and Kernig's sign. A lumber puncture yielded clouded fluid with a WBC 11,200/μl (polynuclear cell 94%), 758 mg/dl of protein, 1 mg/dl of glucose, 0.007 of cerebrospinal fluid-blood glucose ratio and Gram positive cocci. Diffusion-weighted images on brain MRI showed no signal intensity in bilateral ventricles at admission. He was treated with ceftriaxon, vancomycin and ampicillin. Streptococcus salivarius (S. salivarius) was isolated from blood and cerebrospinal fluid. He responded promptly to antibiotics therapy, and within 5 days, he became lucid and afebrile. S. salivarius was sensitive for ceftriaxone, vancomycin and ampicillin. After Day 6, he was treated with ceftriaxone only. We diagnosed his condition as S. salivarius meningitis. He discharged from our hospital at Day 22. Many cases of S. salivarius meningitis were occurred in second and fifth decade. But elderly case was rare. Neurologist should consider that elderly case with bacterial meningitis was caused by S. salivarius.

Surface proteins involved in the adhesion of Streptococcus salivarius to human intestinal epithelial cells

The adhesion properties of 14 Streptococcus salivarius strains to mucus (HT29-MTX) and non-mucus secreting (Caco-2/TC7) human intestinal epithelial cells were investigated. Ability to adhere to these two eukaryotic cell lines greatly differs between strains. The presence of mucus played a major factor in adhesion, likely due to high adhesiveness to mucins present in the native human mucus layer covering the whole cell surface. Only one S. salivarius strain (F6-1), isolated from the feces of a healthy baby, was found to strongly adhere to HT-29 MTX cells at a level comparable to that of Lactobacillus rhamnosus GG, a probiotic strain considered to be highly adherent. By sequencing the genome of F6-1, we were able to identify 36 genes encoding putative surface proteins. Deletion mutants were constructed for six of them and their adhesion abilities on HT-29 MTX cells were checked. Our study confirmed that four of these genes encode adhesins involved in the adhesion of S. salivarius to host cells. Such adhesins were also identified in other S. salivarius strains.

An unusual case of infective pneumocephalus: case report of pneumocephalus exacerbated by continuous positive airway pressure

Background

Pneumocephalus, illustrated by air in the cranial vault is relatively infrequent and generally associated with neurosurgery, trauma, meningitis and barotrauma. However cases of spontaneous non-traumatic pneumocephalus remain rare. While the relationship between continuous positive airway pressure (CPAP) and atraumatic pneumocephalus has been previously reported, to our knowledge the rare presentation associated with sinus wall osteomyelitis has never been described. We summarize here the case of a 67-year-old woman’s acute presentation of Streptococcus salvarius infection after a sudden drop in her consciousness.

Case presentation

The patient was brought to hospital by family reporting a one week history of sudden deterioration, cognitive decline, and lethargy. The patient presented with reduced arousal, cognitive function (Glasgow Coma Scale: 10, Abbreviated Mental Test Score:CS, 0 AMTS), and no history of trauma. Computed Tomography (CT) imaging was ordered and identified a significant pneumocephalus with no cranial defect. Further investigations acknowledged possible sinus or middle ear disease, which was highlighted by the discovery of S. salivarius by polymerase chain reaction (PCR) and potentially exacerbated by the use of nocturnal continuous positive airway pressure (CPAP). The patient made a complete recovery by eliminating likely causative factors and long term regimental antibiotics administration.

Conclusion

This case highlights a rare neurological presentation of S. salivarius infection with a mixed aetiology of spontaneous pneumocephalus. This case features an atypical complication associated with CPAP use, and to our knowledge is the first case to be associated with sinus wall osteomyelitis. Recognition of the clinical features and risk factors for spontaneous pneumocephalus –while rare—serve to broaden our clinical index of suspicion when presented with patients experiencing neurological deficit. Information from this case may also aid in improving prevention, early diagnosis, and future management.

Diversity of Integrative and Conjugative Elements of Streptococcus salivarius and Their Intra- and Interspecies Transfer

Integrative and conjugative elements (ICEs) are widespread chromosomal mobile genetic elements which can transfer autonomously by conjugation in bacteria. Thirteen ICEs with a conjugation module closely related to that of ICESt3 of Streptococcus thermophilus were characterized in Streptococcus salivarius by whole-genome sequencing. Sequence comparison highlighted ICE evolution by shuffling of 3 different integration/excision modules (for integration in the 3' end of the fda, rpsI, or rpmG gene) with the conjugation module of the ICESt3 subfamily. Sequence analyses also pointed out a recombination occurring at oriT (likely mediated by the relaxase) as a mechanism of ICE evolution. Despite a similar organization in two operons including three conserved genes, the regulation modules show a high diversity (about 50% amino acid sequence divergence for the encoded regulators and presence of unrelated additional genes) with a probable impact on the regulation of ICE activity. Concerning the accessory genes, ICEs of the ICESt3 subfamily appear particularly rich in restriction-modification systems and orphan methyltransferase genes. Other cargo genes that could confer a selective advantage to the cell hosting the ICE were identified, in particular, genes for bacteriocin synthesis and cadmium resistance. The functionality of 2 ICEs of S. salivarius was investigated. Autonomous conjugative transfer to other S. salivarius strains, to S. thermophilus, and to Enterococcus faecalis was observed. The analysis of the ICE-fda border sequence in these transconjugants allowed the localization of the DNA cutting site of the ICE integrase.IMPORTANCE The ICESt3 subfamily of ICEs appears to be widespread in streptococci and targets diverse chromosomal integration sites. These ICEs carry diverse cargo genes that can confer a selective advantage to the host strain. The maintenance of these mobile genetic elements likely relies in part on self-encoded restriction-modification systems. In this study, intra- and interspecies transfer was demonstrated for 2 ICEs of S. salivarius Closely related ICEs were also detected in silico in other Streptococcus species (S. pneumoniae and S. parasanguinis), thus indicating that diffusion of ICESt3-related elements probably plays a significant role in horizontal gene transfer (HGT) occurring in the oral cavity but also in the digestive tract, where S. salivarius is present.

Oral cavities of healthy infants harbour high proportions of Streptococcus salivarius strains with phenotypic and genotypic resistance to multiple classes of antibiotics

Emerging antibiotic resistance in the oropharyngeal microbiota, of which Streptococcus salivarius is a prominent species, represents a challenge for treating paediatric populations. In this study, we investigated the role of Streptococcussalivarius as a reservoir for antibiotic resistance genes (ARG) in the oral microbiota by analysing 95 Streptococcussalivarius isolates from 22 healthy infants (2-16 months of age). MICs of penicillin G, amoxicillin, erythromycin, tetracycline, doxycycline and streptomycin were determined. ARG profiles were assessed in a subset of 21 strains by next-generation sequencing of genomes, followed by searches of assembled reads against the Comprehensive Antibiotic Resistance Database. Strains resistant to erythromycin, penicillins and tetracyclines were isolated from 83.3, 33.3 and 16.6 %, respectively, of infants aged 2 to 8 months with no prior antibiotic treatment. These percentages were100.0, 66.6 and 50.0 %, by 13 to 16 months of age. ARG or polymorphisms associated with antibiotic resistance were the most prevalent and involved genes for macrolide efflux (mel, mefA/E and macB), ribosomal protection [erm(B), tet(M) and tet(O)] and β-lactamase-like proteins. Phylogenetically related strains showing multidrug-resistant phenotypes harboured multidrug efflux ARG. Polymorphic genes associated with antibiotic resistance to drugs affecting DNA replication, folate synthesis, RNA/protein synthesis and regulators of antibiotic stress responses were detected. These data imply that Streptococcussalivarius strains established during maturation of the oral microbiota harbour a diverse array of functional ARG, even in the absence of antibiotic selective pressures, highlighting a potential role for this species in shaping antibiotic susceptibility profiles of oropharyngeal communities.

Peroxy Pyruvic Acid-Containing Topical Anti-Infective: A Potential Candidate for a Wound Instillation Solution

Objective: Evaluate the therapeutic properties of a peroxy pyruvic acid (PPA)-containing topical anti-infective in a human ex-vivo model that replicates the natural conditions of a human chronic wound. Approach: Wound material was extracted from patients with nonhealing diabetic ulcers, venous stasis ulcers, and arterial wounds. Microbial species were identified, and wound colonization was quantified. Extracted samples were then exposed to a PPA-containing topical anti-infective as an instillation solution with negative pressure wound therapy NPWT at concentrations of 1,000, 1,500, or 2,500 ppm for a period of 1, 5, or 10 min to determine the effect of exposure on isolated pathogens, including effect on proteins. Results: A total of 32 samples were collected from patients. Samples presented with a range of bacteria and fungi representing 14 genera and 22 species, many of which are or are evolving to be resistant to many, if not most, current systemic antibiotics. Thirteen of twenty-three samples (57%) from chronic wounds had bacteria counts ≥10⁵ and most were 6 logs or more. Seven of 10 samples (70%) from acute wounds had bacteria counts ≤10⁵ and most were much lower. Exposure to PPA-containing topical anti-infective at 1,000 ppm killed all bacteria and fungi in all samples within 1 min of exposure. Innovation: PPA-containing topical anti-infective is a potentially valuable clinical option for NPWT. Conclusion: PPA-containing topical anti-infective is a potential candidate for use as an NPWT instillation solution for the treatment of wound infections caused by susceptible pathogens.

Resistance Genes and Genetic Elements Associated with Antibiotic Resistance in Clinical and Commensal Isolates of Streptococcus salivarius

The diversity of clinical (n = 92) and oral and digestive commensal (n = 120) isolates of Streptococcus salivarius was analyzed by multilocus sequence typing (MLST). No clustering of clinical or commensal strains can be observed in the phylogenetic tree. Selected strains (92 clinical and 46 commensal strains) were then examined for their susceptibilities to tetracyclines, macrolides, lincosamides, aminoglycosides, and phenicol antibiotics. The presence of resistance genes tet(M), tet(O), erm(A), erm(B), mef(A/E), and catQ and associated genetic elements was investigated by PCR, as was the genetic linkage of resistance genes. High rates of erythromycin and tetracycline resistance were observed among the strains. Clinical strains displayed either the erm(B) (macrolide-lincosamide-streptogramin B [MLSB] phenotype) or mef(A/E) (M phenotype) resistance determinant, whereas almost all the commensal strains harbored the mef(A/E) resistance gene, carried by a macrolide efflux genetic assembly (MEGA) element. A genetic linkage between a macrolide resistance gene and genes of Tn916 was detected in 23 clinical strains and 5 commensal strains, with a predominance of Tn3872 elements (n = 13), followed by Tn6002 (n = 11) and Tn2009 (n = 4) elements. Four strains harboring a mef(A/E) gene were also resistant to chloramphenicol and carried a catQ gene. Sequencing of the genome of one of these strains revealed that these genes colocalized on an IQ-like element, as already described for other viridans group streptococci. ICESt3-related elements were also detected in half of the isolates. This work highlights the potential role of S. salivarius in the spread of antibiotic resistance genes both in the oral sphere and in the gut.

Comparison of antibiotic susceptibility in viridans group streptococci in low and high antibiotic-prescribing General Practices

WHAT IS KNOWN AND OBJECTIVE

Antibiotic resistance has become a global public health issue. Most antibiotics are prescribed in the community, although there is less stewardship of such agents in the community compared to secondary and tertiary care. Few studies have attempted to examine the prescribing practices in General Practice and its impact on antibiotic resistance and, therefore, a study was performed in order to compare antibiotic susceptibilities of commensal viridans group streptococci (VGS) obtained from patient cohorts in General Practices (GP), who were high and low prescribers of oral antibiotics.

METHOD

Sixty-five patients (<1 month-81 years; 77% female: 23% male) were enrolled onto the study, and viridans group streptococci (n = 5/patient) were collected from each patient's nasal passages and oropharynx region and tested for antibiotic susceptibility against (i) tetracyclines (doxycycline); (ii) macrolides (erythromycin); (iii) β-lactams (penicillin G); and (iv) fluoroquinolones (ofloxacin & levofloxacin).

RESULTS AND DISCUSSION

There were no significant differences in MICs between high and low GP prescribers with doxycycline (P = 0·094), erythromycin (P = 0·122), ofloxacin (P = 0·193) and levofloxacin (P = 0·058). However, there was a significant difference between high and low GP practices with regard to penicillin G (P = 0·031). This finding is important as the β-lactams are the most commonly prescribed oral antibiotic in the community.

WHAT IS NEW AND CONCLUSION

This study demonstrates that high prescribing practices may lead to an altered (higher) level of resistance to these agents in the commensal VGS population, which may be important as reservoirs of antibiotic resistance determinants in subsequent horizontal gene transfer events, particularly with newly colonizing pathogens, including pneumococci. Primary care physicians should be aware that increased prescribing of antibiotics may led to increased level of penicillin resistance.

Genomics of Streptococcus salivarius, a major human commensal

The salivarius group of streptococci is of particular importance for humans. This group consists of three genetically similar species, Streptococcus salivarius, Streptococcus vestibularis and Streptococcus thermophilus. S. salivarius and S. vestibularis are commensal organisms that may occasionally cause opportunistic infections in humans, whereas S. thermophilus is a food bacterium widely used in dairy production. We developed Multilocus sequence typing (MLST) and comparative genomic analysis to confirm the clear separation of these three species. These analyses also identified a subgroup of four strains, with a core genome diverging by about 10%, in terms of its nucleotide sequence, from that of S. salivarius sensu stricto. S. thermophilus species displays a low level of nucleotide variability, due to its recent emergence with the development of agriculture. By contrast, nucleotide variability is high in the other two species of the salivarius group, reflecting their long-standing association with humans. The species of the salivarius group have genome sizes ranging from the smallest (∼ 1.7 Mb for S. thermophilus) to the largest (∼ 2.3 Mb for S. salivarius) among streptococci, reflecting genome reduction linked to a narrow, nutritionally rich environment for S. thermophilus, and natural, more competitive niches for the other two species. Analyses of genomic content have indicated that the core genes of S. salivarius account for about two thirds of the genome, indicating considerable variability of gene content and differences in potential adaptive features. Furthermore, we showed that the genome of this species is exceptionally rich in genes encoding surface factors, glycosyltransferases and response regulators. Evidence of widespread genetic exchanges was obtained, probably involving a natural competence system and the presence of diverse mobile elements. However, although the S. salivarius strains studied were isolated from several human body-related sites (all levels of the digestive tract, skin, breast milk, and body fluids) and included clinical strains, no genetic or genomic niche-specific features could be identified to discriminate specific group.

The pathogenicity of the Streptococcus genus

Streptococcus infections are still one of the important problems facing contemporary medicine. As the World Health Organization (WHO) warns, Streptococcus pneumoniae is responsible for the highest number of pneumonia cases all over the world. Despite an increasing number of pneumococcal vaccinations, incidences of disease connected to this pathogen's infection stay at the same level, which is related to a constantly increasing number of infections caused by nonvaccinal serotypes. Unfortunately, the pathogenicity of bacteria of the Streptococcus genus is also connected to species considered to be physiological flora in humans or animals and, additionally, new species exhibiting pathogenic potential have been discovered. This paper presents an opinion concerning the epidemiology of streptococci infections based on case studies and other publications devoted to this problem. It also sheds new light based on recent reports on the prevention of protective vaccinations application in the case of streptococci infections.

Developing oral probiotics from Streptococcus salivarius

Considerable human illness can be linked to the development of oral microbiota disequilibria. The predominant oral cavity commensal, Streptococcus salivarius has emerged as an important source of safe and efficacious probiotics, capable of fostering more balanced, health-associated oral microbiota. Strain K12, the prototype S. salivarius probiotic, originally introduced to counter Streptococcus pyogenes infections, now has an expanded repertoire of health-promoting applications. K12 and several more recently proposed S. salivarius probiotics are now being applied to control diverse bacterial consortia infections including otitis media, halitosis and dental caries. Other potential applications include upregulation of immunological defenses against respiratory viral infections and treatment of oral candidosis. An overview of the key steps required for probiotic development is also presented.

Using PCR-based detection and genotyping to trace Streptococcus salivarius meningitis outbreak strain to oral flora of radiology physician assistant

We recently investigated three cases of bacterial meningitis that were reported from a midwestern radiology clinic where facemasks were not worn during spinal injection of contrast agent during myelography procedures. Using pulsed field gel electrophoresis we linked a case strain of S. salivarius to an oral specimen of a radiology physician assistant (RPA). We also used a real-time PCR assay to detect S. salivarius DNA within a culture-negative cerebrospinal fluid (CSF) specimen. Here we extend this investigation through using a nested PCR/sequencing strategy to link the culture-negative CSF specimen to the case strain. We also provide validation of the real-time PCR assay used, demonstrating that it is not solely specific for Streptococcus salivarius, but is also highly sensitive for detection of the closely related oral species Streptococcus vestibularis. Through using multilocus sequence typing and 16S rDNA sequencing we further strengthen the link between the CSF case isolate and the RPA carriage isolate. We also demonstrate that the newly characterized strains from this study are distinct from previously characterized S. salivarius strains associated with carriage and meningitis.