Staphylococcus aureus Colonization of the Human Nose and Interaction with Other Microbiome Members

Draft genome sequences for a Staphylococcus aureus and a Staphylococcus haemolyticus isolate from nasal swab samples from healthy females

Staphylococcus aureus and Staphylococcus haemolyticus are common members of the human microbiota, but they are also opportunistic pathogens. To identify antibiotic resistance in healthy individuals, we present the genome sequences of S. aureus 139 N-1 and S. haemolyticus 173 N-3, both isolated from nasal swab samples from asymptomatic female participants.

Phenotypic and genotypic characterization of commensal staphylococci isolated from young volunteers in Alexandria, Egypt

Nasally colonized staphylococci carry antibiotic resistance genes and may lead to serious opportunistic infections. We are investigating nasal carriage of Staphylococcus aureus and Staphylococci other than S. aureus (SOSA) among young volunteers in Egypt to determine their risk potential. Nasal swabs collected over 1 week in June 2019 from 196 volunteers were cultured for staphylococcus isolation. The participants were interviewed to assess sex, age, general health, hospitalization and personal hygiene habits. Identification was carried out using biochemical tests and VITEK 2 automated system. Disc diffusion and minimum inhibitory concentration tests were performed to determine antibiotic susceptibility. Screening for macrolide resistance genes (ermA, ermB, ermC, ermT and msrA) was performed using polymerase chain reaction. Thirty four S. aureus and 69 SOSA were obtained. Multi-drug resistance (MDR) was detected among most staphylococcal species, ranging from 30.77% among S. hominis to 50% among S. epidermidis. Phenotypic resistance to all tested antibiotics, except for linezolid, was observed. Susceptibility to rifampicin, vancomycin and teicoplanin was highest. ermB showed the highest prevalence among all species (79.41% and 94.2% among S. aureus and SOSA, respectively), and constitutive macrolide-lincosamide-streptogramin B (MLSB) resistance was equally observed in S. aureus and SOSA (11.11% and 16.22%, respectively), whereas inducible MLSB resistance was more often found in S. aureus (77.78% and 43.24%, respectively). The species or resistance level of the carried isolates were not significantly associated with previous hospitalization or underlying diseases. Although over all colonization and carriage of resistance genes are within normal ranges, the increased carriage of MDR S. aureus is alarming. Also, the fact that many macrolide resitance genes were detected should be a warning sign, particularly in case of MLSB inducible phenotype. More in depth analysis using whole genome sequencing would give a better insight into the MDR staphylococci in the community in Egypt.

Collaborative Cross mice have diverse phenotypic responses to infection with Methicillin-resistant Staphylococcus aureus USA300

Staphylococcus aureus (S. aureus) is an opportunistic pathogen causing diseases ranging from mild skin infections to life threatening conditions, including endocarditis, pneumonia, and sepsis. To identify host genes modulating this host-pathogen interaction, we infected 25 Collaborative Cross (CC) mouse strains with methicillin-resistant S. aureus (MRSA) and monitored disease progression for seven days using a surgically implanted telemetry system. CC strains varied widely in their response to intravenous MRSA infection. We identified eight 'susceptible' CC strains with high bacterial load, tissue damage, and reduced survival. Among the surviving strains, six with minimal colonization were classified as 'resistant', while the remaining six tolerated higher organ colonization ('tolerant'). The kidney was the most heavily colonized organ, but liver, spleen and lung colonization were better correlated with reduced survival. Resistant strains had higher pre-infection circulating neutrophils and lower post-infection tissue damage compared to susceptible and tolerant strains. We identified four CC strains with sexual dimorphism: all females survived the study period while all males met our euthanasia criteria earlier. In these CC strains, males had more baseline circulating monocytes and red blood cells. We identified several CC strains that may be useful as new models for endocarditis, myocarditis, pneumonia, and resistance to MRSA infection. Quantitative Trait Locus (QTL) analysis identified two significant loci, on Chromosomes 18 and 3, involved in early susceptibility and late survival after infection. We prioritized Npc1 and Ifi44l genes as the strongest candidates influencing survival using variant analysis and mRNA expression data from kidneys within these intervals.

Bacteriocins: potentials and prospects in health and agrifood systems

Bacteriocins are highly diverse, abundant, and heterogeneous antimicrobial peptides that are ribosomally synthesized by bacteria and archaea. Since their discovery about a century ago, there has been a growing interest in bacteriocin research and applications. This is mainly due to their high antimicrobial properties, narrow or broad spectrum of activity, specificity, low cytotoxicity, and stability. Though initially used to improve food quality and safety, bacteriocins are now globally exploited for innovative applications in human, animal, and food systems as sustainable alternatives to antibiotics. Bacteriocins have the potential to beneficially modulate microbiota, providing viable microbiome-based solutions for the treatment, management, and non-invasive bio-diagnosis of infectious and non-infectious diseases. The use of bacteriocins holds great promise in the modulation of food microbiomes, antimicrobial food packaging, bio-sanitizers and antibiofilm, pre/post-harvest biocontrol, functional food, growth promotion, and sustainable aquaculture. This can undoubtedly improve food security, safety, and quality globally. This review highlights the current trends in bacteriocin research, especially the increasing research outputs and funding, which we believe may proportionate the soaring global interest in bacteriocins. The use of cutting-edge technologies, such as bioengineering, can further enhance the exploitation of bacteriocins for innovative applications in human, animal, and food systems.

Bacterial contamination potential of personal protective equipment itself in dental aerosol-producing treatments

Personal protective equipment (PPE) has long been a high priority in dental aerosol-producing treatments. Since COVID-19 pandemic, its importance has increased yet again. While importance of PPE in preventing transmission and thus possible infection of pathogens is well known, contamination potential of PPE after treatment itself is less investigated. This review aims to give an overview of the current literature and contamination potential (viral, blood, bacterial) of components of protective equipment itself. The literature search was performed using the Medline database; furthermore, a hand search was conducted. Last search took place on 23 November 2022. Two categories of hygiene-related keywords were formed (category A: mask, face shield, goggles, eyewear, personal protective equipment; category B: contamination, aerosol). Each keyword from one category was combined with all keywords from the other one. In addition, the keyword "dental" was always added. First, a title and abstract screening was performed. Afterward, a full-text analysis was followed for the included studies. A total of 648 search hits were found in the Medline database. 47 were included after title and abstract screening. 22 studies were excluded after full-text analysis, 25 studies were included. The hand search resulted in 4 studies that were included. Bacterial contamination of PPE after treatment has been adequately studied, contamination with blood less. Microorganisms mainly originate from the oral and cutaneous flora; however, a transmission of potential pathogens like Staphylococcus aureus or Escherichia coli was also described. Studies showing transmission pathways starting from PPE and its various components are lacking. No measures have yet been described that fully protect the protective equipment from contamination. There is growing awareness that PPE itself can be a source of pathogen transmission, and thus possible infection. Therefore, not only wearing of protective clothing, but also conscious handling of it is crucial for transmission and possible infection prevention. However, studies showing transmission pathways starting from PPE and its various components are lacking. Several studies have investigated what measures can be taken to protect the protective equipment itself. So far, none of the methods evaluated can prevent contamination of PPE.

Derivation of a novel antimicrobial peptide from the Red Sea Brine Pools modified to enhance its anticancer activity against U2OS cells

Cancer associated drug resistance is a major cause for cancer aggravation, particularly as conventional therapies have presented limited efficiency, low specificity, resulting in long term deleterious side effects. Peptide based drugs have emerged as potential alternative cancer treatment tools due to their selectivity, ease of design and synthesis, safety profile, and low cost of manufacturing. In this study, we utilized the Red Sea metagenomics database, generated during AUC/KAUST Red Sea microbiome project, to derive a viable anticancer peptide (ACP). We generated a set of peptide hits from our library that shared similar composition to ACPs. A peptide with a homeodomain was selected, modified to improve its anticancer properties, verified to maintain high anticancer properties, and processed for further in-silico prediction of structure and function. The peptide's anticancer properties were then assessed in vitro on osteosarcoma U2OS cells, through cytotoxicity assay (MTT assay), scratch-wound healing assay, apoptosis/necrosis detection assay (Annexin/PI assay), RNA expression analysis of Caspase 3, KI67 and Survivin, and protein expression of PARP1. L929 mouse fibroblasts were also assessed for cytotoxicity treatment. In addition, the antimicrobial activity of the peptide was also examined on E coli and S. aureus, as sample representative species of the human bacterial microbiome, by examining viability, disk diffusion, morphological assessment, and hemolytic analysis. We observed a dose dependent cytotoxic response from peptide treatment of U2OS, with a higher tolerance in L929s. Wound closure was debilitated in cells exposed to the peptide, while annexin fluorescent imaging suggested peptide treatment caused apoptosis as a major mode of cell death. Caspase 3 gene expression was not altered, while KI67 and Survivin were both downregulated in peptide treated cells. Additionally, PARP-1 protein analysis showed a decrease in expression with peptide exposure. The peptide exhibited minimal antimicrobial activity on critical human microbiome species E. coli and S. aureus, with a low inhibition rate, maintenance of structural morphology and minimal hemolytic impact. These findings suggest our novel peptide displayed preliminary ACP properties against U2OS cells, through limited specificity, while triggering apoptosis as a primary mode of cell death and while having minimal impact on the microbiological species E. coli and S. aureus.

Diversity of Staphylococcus aureus isolated from nares of ruminants

AIMS

To examine the diversity of Staphylococcus aureus isolated from nasal swabs of ruminants in Rwanda.

METHODS AND RESULTS

A total of 454 nasal swabs from 203 cows, 170 goats, and 81 sheep were examined for the presence of S. aureus, and 30 S. aureus isolates were detected and characterized pheno- and genotypically. Resistance to penicillin and/or tetracycline was observed. The isolates were assigned to eight different spa types (t21057 (novel), t10103, t18853, t20842, t318, t355, t458, and t9432) belonging to six clonal complexes (CCs) (CC152, CC30, CC3591, CC3666, CC522, and CC97). Panton-Valentine leukocidin (PVL) genes (lukF-PV/lukS-PV), the bovine leukocidin genes (lukM/lukF-P83), and the human and bovine variants of the toxic shock syndrome toxin gene tst-1 variants were detected.

CONCLUSION

These findings demonstrate that the nares of ruminants in Rwanda are colonized with mastitis-associated S. aureus, including lineages that are also carried by humans, underscoring the zoonotic risk, especially for livestock keepers. These results highlight the crucial importance of hygiene measures when handling livestock.

Expression and characterization of novel chimeric endolysin CHAPk-SH3bk against biofilm-forming methicillin-resistant Staphylococcus aureus

The continuous evolution of antibiotic resistance in methicillin-resistant Staphylococcus aureus (MRSA) due to the misuse of antibiotics lays out the need for the development of new antimicrobials with higher activity and lower resistance. In this study, we have expressed novel chimeric endolysin CHAPk-SH3bk derived from LysK to investigate its antibacterial activity against planktonic and biofilm-forming MRSA. The molecular docking and MD simulation results identified critical amino acids (ASP47, ASP56, ARG71, and Gly74) of CHAPk domain responsible for its catalytic activity. Chimeric endolysin CHAPk-SH3bk showed an effective binding to peptidoglycan fragment using 14 hydrogen bonds. The in-vitro antibacterial assays displayed higher activity of CHAPk against planktonic MRSA with 2-log10 reduction in 2 h. Both CHAPk and CHAPk-SH3bk displayed bactericidal activity against MRSA with ∼4log10 and ∼3.5log10 reduction in 24 h. Biofilm reduction activity displayed CHAPk-SH3bk reduced 33 % and 60 % of hospital-associated ATCC®BAA-44™ and bovine origin SA1 respectively. The CHAPk treatment reduced 47 % of the preformed biofilm formed by bovine-origin MRSA SA1. This study indicates an effective reduction of preformed MRSA biofilms of human and animal origin using novel chimeric construct CHAPk-SH3bk. Stating that the combination and shuffling of different domains of phage endolysin potentially increase its bacteriolytic effectiveness against MRSA.

Detection of Staphylococcus aureus from nares of elderly living in a Brazilian nursing home

Asymptomatically nasal colonization by Staphylococcus aureus is a well-established risk factor for S. aureus infections. The aimed of the study was to identify the prevalence and factors associated with nasal carriage of S. aureus and Methicillin-resistant S. aureus (MRSA) from individuals residing in one Brazilian nursing home (NH). Three time-separate nasal swab collections were obtained from the elderly enrolled. The S. aureus isolates identified were submitted to Antimicrobial Susceptibility test (AST). The study showed a high prevalence of S. aureus (n = 9; 60%) and MRSA (n = 4; 26.7%) among elderly. Resistance to erythromycin was the most detected. S. aureus or MRSA colonization could not be associated to the data collected on demographics, personal habits, and medical history of the participants. Despite the small number of individuals enrolled, our study can contribute to improve the control of S. aureus and MRSA dissemination within the community, especially among the most vulnerable like the elderly.

Virulence attributes of successful methicillin-resistant Staphylococcus aureus lineages

Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of severe and often fatal infections. MRSA epidemics have occurred in waves, whereby a previously successful lineage has been replaced by a more fit and better adapted lineage. Selection pressures in both hospital and community settings are not uniform across the globe, which has resulted in geographically distinct epidemiology. This review focuses on the mechanisms that trigger the establishment and maintenance of current, dominant MRSA lineages across the globe. While the important role of antibiotic resistance will be mentioned throughout, factors which influence the capacity of S. aureus to colonize and cause disease within a host will be the primary focus of this review. We show that while MRSA possesses a diverse arsenal of toxins including alpha-toxin, the success of a lineage involves more than just producing toxins that damage the host. Success is often attributed to the acquisition or loss of genetic elements involved in colonization and niche adaptation such as the arginine catabolic mobile element, as well as the activity of regulatory systems, and shift metabolism accordingly (e.g., the accessory genome regulator, agr). Understanding exactly how specific MRSA clones cause prolonged epidemics may reveal targets for therapies, whereby both core (e.g., the alpha toxin) and acquired virulence factors (e.g., the Panton-Valentine leukocidin) may be nullified using anti-virulence strategies.

Systematic mining of the human microbiome identifies antimicrobial peptides with diverse activity spectra

Human-associated bacteria secrete modified peptides to control host physiology and remodel the microbiota species composition. Here we scanned 2,229 Human Microbiome Project genomes of species colonizing skin, gastrointestinal tract, urogenital tract, mouth and trachea for gene clusters encoding RiPPs (ribosomally synthesized and post-translationally modified peptides). We found 218 lanthipeptides and 25 lasso peptides, 70 of which were synthesized and expressed in E. coli and 23 could be purified and functionally characterized. They were tested for activity against bacteria associated with healthy human flora and pathogens. New antibiotics were identified against strains implicated in skin, nasal and vaginal dysbiosis as well as from oral strains selectively targeting those in the gut. Extended- and narrow-spectrum antibiotics were found against methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococci. Mining natural products produced by human-associated microbes will enable the elucidation of ecological relationships and may be a rich resource for antimicrobial discovery.

Optimization of high-throughput 16S rRNA gene amplicon sequencing: an assessment of PCR pooling, mastermix use and contamination

16S rRNA gene sequencing is widely used to characterize human and environmental microbiomes. Sequencing at scale facilitates better powered studies but is limited by cost and time. We identified two areas in our 16S rRNA gene library preparation protocol where modifications could provide efficiency gains, including (1) pooling of multiple PCR amplifications per sample to reduce PCR drift and (2) manual preparation of mastermix to reduce liquid handling. Using nasal samples from healthy human participants and a serially diluted mock microbial community, we compared alpha and beta diversity, and compositional abundance where the PCR amplification was conducted in triplicate, duplicate or as a single reaction, and where manually prepared or premixed mastermix was used. One hundred and fifty-eight 16S rRNA gene sequencing libraries were prepared, including a replicate experiment. Comparing PCR pooling strategies, we found no significant difference in high-quality read counts and alpha diversity, and beta diversity by Bray-Curtis index clustered by replicate on principal coordinate analysis (PCoA) and non-metric dimensional scaling (NMDS) analysis. Choice of mastermix had no significant impact on high-quality read and alpha diversity, and beta diversity by Bray-Curtis index clustered by replicate in PCoA and NMDS analysis. Importantly, we observed contamination and variability of rare species (<0.01 %) across replicate experiments; the majority of contaminants were accounted for by removal of species present at <0.1 %, or were linked to reagents (including a primer stock). We demonstrate no requirement for pooling of PCR amplifications or manual preparation of PCR mastermix, resulting in a more efficient 16S rRNA gene PCR protocol.

Lugdunin production and activity in Staphylococcus lugdunensis isolates are associated with its genotypes

Lugdunin produced by Staphylococcus lugdunensis has been shown to have broad inhibitory activity against Gram-positive bacteria; however, lugdunin activity among S. lugdunensis isolates and its association with different agr, SCCmec, and sequence types remain unclear. We used matrix-assisted laser desorption ionization-time-of-flight mass spectrometry to identify S. lugdunensis and collected 202 S. lugdunensis samples for further assays. Agar spot tests were performed to characterize S. lugdunensis lugdunin production and activity. Multilocus sequence typing, SCCmec, and agr genotyping were performed on S. lugdunensis. In all, 91 Staphylococcus aureus strains with varying vancomycin susceptibilities were used to examine lugdunin activity in S. lugdunensis. In total, 48 S. lugdunensis strains (23.8%) were found to be oxacillin-resistant S. lugdunensis (ORSL), whereas 154 (76.2%) were classified as oxacillin-sensitive S. lugdunensis (OSSL). Moreover, 16 (33.3%) ORSL and 35 (22.7%) OSSL strains showed antibacterial activity against S. aureus. Our data showed that most lugdunin-producing ORSL strains (14/48, 29.2%) were of ST3-SCCmec V-agr II genotypes, whereas most lugdunin-producing OSSL strains (15/154, 9.7%) were of ST3-agr II, followed by ST1-agr I (10/154, 6.5%). Our data also revealed that lugdunin exhibited weak inhibitory activity against the VISA ST239 isolate. In addition, we observed that ST239 VSSA was more resistant to lugdunin than ST5, ST59, and ST45 VSSA. Taken together, our data pioneered the epidemiology of lugdunin production in S. lugdunensis isolates and revealed its association with genotypes. However, further molecular and bioinformatics investigations are needed to elucidate the regulatory mechanisms of lugdunin production and activity. IMPORTANCE Lugdunin is active against both methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci by dissipating their membrane potential. However, the association of lugdunin activity with the genotypes of Staphylococcus lugdunensis has not been addressed. Here, we show the high prevalence of lugdunin-producing strains among ST1 (83.3%), ST2 (66.7%), and ST3 (53.3%) S. lugdunensis. Moreover, we identified the antibacterial activity of lugdunin-producing strains against VISA and hVISA. These results shed light on the potential application of lugdunin for the treatment of drug-resistant pathogens.

Proteomic Profiles and Protein Network Analysis of Primary Human Leukocytes Revealed Possible Clearance Biomarkers for Staphylococcus aureus Infection

Staphylococcus aureus is a serious pathogen that can survive within host cells after a typical course of treatment completion, leading to chronic infection. Knowledge of host proteomic patterns after clearance of this pathogen from cells is limited. Here, we looked for S. aureus clearance biomarkers produced by in vitro-infected leukocytes. Extracellular proteins from primary human leukocytes infected with S. aureus ATCC 25923 were investigated as possible treatment-monitoring clearance biomarkers by applying a proteomics approach combining liquid chromatography with tandem mass spectrometry (LC-MS/MS) and protein interaction network analysis. It was found that the expression patterns of proteins secreted by S. aureus-infected leukocytes differed among stages of infection. Proteomic profiles showed that an ATPase, aminophospholipid transporter-like, Class I, type 8A, member 2 (ATP8A2) was expressed in the clearance stage and was not detected at any earlier stage or in uninfected controls. Protein network analysis showed that TERF2 (telomeric repeat-binding factor 2), ZNF440 (zinc finger protein 440), and PPP1R14A (phosphatase 1 regulatory subunit 14A) were up-regulated, while GLE1, an essential RNA-export mediator, was suppressed in both infection and clearance stages, suggesting their potential roles in S. aureus infection and clearance. These findings are the first to report that the ATP8A2 has potential as a clearance biomarker for S. aureus infection.

Retrospective Study on Staphylococcus aureus Resistance Profile and Antibiotic Use in a Pediatric Population

The growing phenomenon of antibiotic resistance and the presence of limited data concerning the pediatric area prompted us to focus on Staphylococcus aureus infection in this study, its antibiotic resistance profile, and the therapeutic management of affected children. We conducted a retrospective study by collecting clinical data on infants and children with antibiogram-associated S. aureus infection. We enrolled 1210 patients with a mean age of 0.9 years. We analyzed the resistance patterns and found 61.5% resistance to oxacillin, 58.4% resistance to cephalosporins, 41.6% resistance to aminoglycosides, and 38.3% resistance to fluoroquinolones. Importantly, we found no resistance to glycopeptides, a key antibiotic for MRSA infections whose resistance is increasing worldwide. We also found that the main risk factors associated with antibiotic resistance are being aged between 0 and 28 days, the presence of devices, and comorbidities. Antibiotic resistance is a growing concern; knowing the resistance profiles makes it possible to better target the therapy; however, it is important to use antibiotics according to the principles of antibiotic stewardship to limit their spread.

Novel evidence on sepsis-inducing pathogens: from laboratory to bedside

Sepsis is a life-threatening condition and a significant cause of preventable morbidity and mortality globally. Among the leading causative agents of sepsis are bacterial pathogens Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Pseudomonas aeruginosa, and Streptococcus pyogenes, along with fungal pathogens of the Candida species. Here, we focus on evidence from human studies but also include in vitro and in vivo cellular and molecular evidence, exploring how bacterial and fungal pathogens are associated with bloodstream infection and sepsis. This review presents a narrative update on pathogen epidemiology, virulence factors, host factors of susceptibility, mechanisms of immunomodulation, current therapies, antibiotic resistance, and opportunities for diagnosis, prognosis, and therapeutics, through the perspective of bloodstream infection and sepsis. A list of curated novel host and pathogen factors, diagnostic and prognostic markers, and potential therapeutical targets to tackle sepsis from the research laboratory is presented. Further, we discuss the complex nature of sepsis depending on the sepsis-inducing pathogen and host susceptibility, the more common strains associated with severe pathology and how these aspects may impact in the management of the clinical presentation of sepsis.

Microbiota Profile of the Nasal Cavity According to Lifestyles in Healthy Adults in Santiago, Chile

BACKGROUND

The respiratory microbiome is dynamic, varying between anatomical niches, and it is affected by various host and environmental factors, one of which is lifestyle. Few studies have characterized the upper respiratory tract microbiome profile according to lifestyle. We explored the association between lifestyles and microbiota profiles in the upper respiratory tract of healthy adults.

METHODS

We analyzed nasal samples from 110 healthy adults who were living in Santiago, Chile, using 16S ribosomal RNA gene-sequencing methods. Volunteers completed a structured questionnaire about lifestyle.

RESULTS

The composition and abundance of taxonomic groups varied across lifestyle attributes. Additionally, multivariate models suggested that alpha diversity varied in the function of physical activity, nutritional status, smoking, and the interaction between nutritional status and smoking, although the significant impact of those variables varied between women and men. Although physical activity and nutritional status were significantly associated with all indexes of alpha diversity among women, the diversity of microbiota among men was associated with smoking and the interaction between nutritional status and smoking.

CONCLUSIONS

The alpha diversity of nasal microbiota is associated with lifestyle attributes, but these associations depend on sex and nutritional status. Our results suggest that future studies of the airway microbiome may provide a better resolution if data are stratified for differences in sex and nutritional status.

Unveiling the Relevance of the Oral Cavity as a Staphylococcus aureus Colonization Site and Potential Source of Antimicrobial Resistance

Staphylococcus aureus is both a human commensal and a pathogen, that causes serious nosocomial and community-acquired infections. Despite nostrils being considered its preferred host habitat, the oral cavity has been demonstrated to be an ideal starting point for auto-infection and transmission. The antibiotic resistance assessment of S. aureus is a priority and is often reported in clinical settings. This study aimed to explore the prevalence and antimicrobial susceptibility of S. aureus in the oral and nasal cavities of healthy individuals. The participants (n = 101) were subjected to a demographic and clinical background survey, a caries evaluation, and to oral and nasal swabbing. Swabs were cultured in differential/selective media and S. aureus isolates were identified (MALDI-TOF MS) and tested for antibiotic susceptibility (EUCAST/CLSI). Similar S. aureus prevalence was found exclusively on nasal (13.9%) or oral (12.0%) habitats, whereas 9.9% of the population were simultaneous nasal and oral carriers. In oro-nasal cavities, similar antibiotic resistance rates (83.3-81.5%), including MDR (20.8-29.6%), were observed. Notably, 60% (6/10) of the simultaneous nasal and oral carriers exhibited different antibiotic resistance profiles between cavities. This study demonstrates the relevance of the oral cavity as an independent colonization site for S. aureus and as a potential source of antimicrobial resistance, a role which has been widely neglected so far.

Comprehensive Approaches for the Search and Characterization of Staphylococcins

Novel and sustainable approaches are required to curb the increasing threat of antimicrobial resistance (AMR). Within the last decades, antimicrobial peptides, especially bacteriocins, have received increased attention and are being explored as suitable alternatives to antibiotics. Bacteriocins are ribosomally synthesized antimicrobial peptides produced by bacteria as a self-preservation method against competitors. Bacteriocins produced by Staphylococcus, also referred to as staphylococcins, have steadily shown great antimicrobial potential and are currently being considered promising candidates to mitigate the AMR menace. Moreover, several bacteriocin-producing Staphylococcus isolates of different species, especially coagulase-negative staphylococci (CoNS), have been described and are being targeted as a good alternative. This revision aims to help researchers in the search and characterization of staphylococcins, so we provide an up-to-date list of bacteriocin produced by Staphylococcus. Moreover, a universal nucleotide and amino acid-based phylogeny system of the well-characterized staphylococcins is proposed that could be of interest in the classification and search for these promising antimicrobials. Finally, we discuss the state of art of the staphylococcin applications and an overview of the emerging concerns.

Interspecies Interactions within the Host: the Social Network of Group B Streptococcus

Group B Streptococcus (GBS) is a pervasive neonatal pathogen accounting for a combined half a million deaths and stillbirths annually. The most common source of fetal or neonatal GBS exposure is the maternal microbiota. GBS asymptomatically colonizes the gastrointestinal and vaginal mucosa of 1 in 5 individuals globally, although its precise role in these niches is not well understood. To prevent vertical transmission, broad-spectrum antibiotics are administered to GBS-positive mothers during labor in many countries. Although antibiotics have significantly reduced GBS early-onset neonatal disease, there are several unintended consequences, including an altered neonatal microbiota and increased risk for other microbial infections. Additionally, the incidence of late-onset GBS neonatal disease remains unaffected and has sparked an emerging hypothesis that GBS-microbe interactions in developing neonatal gut microbiota may be directly involved in this disease process. This review summarizes our current understanding of GBS interactions with other resident microbes at the mucosal surface from multiple angles, including clinical association studies, agriculture and aquaculture observations, and experimental animal model systems. We also include a comprehensive review of in vitro findings of GBS interactions with other bacterial and fungal microbes, both commensal and pathogenic, along with newly established animal models of GBS vaginal colonization and in utero or neonatal infection. Finally, we provide a perspective on emerging areas of research and current strategies to design microbe-targeting prebiotic or probiotic therapeutic intervention strategies to prevent GBS disease in vulnerable populations.

Antimicrobial effects of nano titanium dioxide and disinfectants on maxillofacial silicones

STATEMENT OF PROBLEM

Deficient hygiene of maxillofacial prostheses can be a source of infection, and various disinfectants, including nano-oxides, have been suggested for the disinfection of silicone prostheses. While maxillofacial silicones involving nano-oxides at different sizes and concentrations have been evaluated in terms of their mechanical and physical properties, reports are lacking on the antimicrobial effect of nano titanium dioxide (TiO₂) incorporated into maxillofacial silicones contaminated by different biofilms.

PURPOSE

The purpose of this in vitro study was to evaluate the antimicrobial effects of 6 different disinfectants and nano TiO₂ incorporation into maxillofacial silicone contaminated with Staphylococcus aureus, Escherichia coli, and Candida albicans biofilms.

MATERIAL AND METHODS

A total of 258 silicone specimens (129 pure silicones and 129 nano TiO₂-incorporated silicones) were fabricated. Specimens in each silicone group (with or without nano TiO₂) were divided into 7 disinfectant groups (control, 0.2% chlorhexidine gluconate, 4% chlorhexidine gluconate, 1% sodium hypochlorite, neutral soap, 100% white vinegar, and effervescent) in each biofilm group. Contaminated specimens were disinfected, and the suspension of each specimen was incubated at 37 °C for 24 hours. Proliferated colonies were recorded in colony-forming units per mL (CFU/mL). The differences in microbial levels among specimens were evaluated to test the effect of the type of silicone and the disinfectant (α=.05).

RESULTS

Significant difference was found among disinfectants regardless of the silicone type (P<.05). Nano TiO₂ incorporation showed an antimicrobial effect on S aureus, E coli, and C albicans biofilms. Nano TiO₂ incorporated silicone cleaned with 4% chlorhexidine gluconate had statistically less C albicans than pure silicone. Using white vinegar or 4% chlorhexidine gluconate led to no E coli on either silicone. Nano TiO₂ incorporated silicone cleaned with effervescent had fewer S aureus or C albicans biofilms.

CONCLUSIONS

The tested disinfectants and nano TiO₂ incorporation into silicone were effective against most of the microorganisms used in this study.

Adding context to the pneumococcal core genes using bioinformatic analysis of the intergenic pangenome of Streptococcus pneumoniae

Introduction: Whole genome sequencing offers great opportunities for linking genotypes to phenotypes aiding in our understanding of human disease and bacterial pathogenicity. However, these analyses often overlook non-coding intergenic regions (IGRs). By disregarding the IGRs, crucial information is lost, as genes have little biological function without expression. Methods/Results: In this study, we present the first complete pangenome of the important human pathogen Streptococcus pneumoniae (pneumococcus), spanning both the genes and IGRs. We show that the pneumococcus species retains a small core genome of IGRs that are present across all isolates. Gene expression is highly dependent on these core IGRs, and often several copies of these core IGRs are found across each genome. Core genes and core IGRs show a clear linkage as 81% of core genes are associated with core IGRs. Additionally, we identify a single IGR within the core genome that is always occupied by one of two highly distinct sequences, scattered across the phylogenetic tree. Discussion: Their distribution indicates that this IGR is transferred between isolates through horizontal regulatory transfer independent of the flanking genes and that each type likely serves different regulatory roles depending on their genetic context.

Detection of antimicrobial producing Staphylococcus from migratory birds: Potential role in nasotracheal microbiota modulation

A collection of 259 staphylococci of 13 different species [212 coagulase-negative (CoNS) and 47 coagulase-positive (CoPS)] recovered from nasotracheal samples of 87 healthy nestling white storks was tested by the spot-on-lawn method for antimicrobial-activity (AA) against 14 indicator bacteria. Moreover, extracts of AP isolates were obtained [cell-free-supernatants (CFS) both crude and concentrated and butanol extracts] and tested against the 14 indicator bacteria. The microbiota modulation capacity of AP isolates was tested considering: (a) intra-sample AA, against all Gram-positive bacteria recovered in the same stork nasotracheal sample; (b) inter-sample AA against a selection of representative Gram-positive bacteria of the nasotracheal microbiota of all the storks (30 isolates of 29 different species and nine genera). In addition, enzymatic susceptibility test was carried out in selected AP isolates and bacteriocin encoding genes was studied by PCR/sequencing. In this respect, nine isolates (3.5%; seven CoNS and two CoPS) showed AA against at least one indicator bacteria and were considered antimicrobial-producing (AP) isolates. The AP isolates showed AA only for Gram-positive bacteria. Three of these AP isolates (S. hominis X3764, S. sciuri X4000, and S. chromogenes X4620) revealed AA on all extract conditions; other four AP isolates only showed activity in extracts after concentration; the remaining two AP isolates did not show AA in any of extract conditions. As for the microbiota modulation evaluation, three of the nine AP-isolates revealed intra-sample AA. It is to highlight the potent inter-sample AA of the X3764 isolate inhibiting 73% of the 29 representative Gram-positive species of the nasotracheal stork microbiota population. On the other hand, enzymatic analysis carried out in the two highest AP isolates (X3764 and X4000) verified the proteinaceous nature of the antimicrobial compound and PCR analysis revealed the presence of lantibiotic-like encoding genes in the nine AP isolates. In conclusion, these results show that nasotracheal staphylococci of healthy storks, and especially CoNS, produce antimicrobial substances that could be important in the modulations of their nasal microbiota.

Microbiology of fracture related infections

Fracture related infection remains a challenging complication that creates a heavy burden for orthopaedic trauma patients, their families, treating physicians and healthcare systems. Even current curative approaches (radical debridement, revision surgery and long-term antibiotics) often result in significant socioeconomic costs and the risk of life-long functional impairment to the patient. The prevalence of osteomyelitis due to trauma and surgical complications does not seem to be diminishing in our society and the emergence of antimicrobial resistance is a major health related concern with global relevance. Despite multi-drug resistant bacteria being on the rise universally, perioperative antibiotic prophylaxis in orthopaedic trauma care has only slightly changed in the last 25 years. Staphylococcus infections remain an increasing global concern, partially due to the resistance mechanisms developed by staphylococci to evade the host immune system and antibiotic treatment, and as such antibiotics are becoming increasingly ineffective. This paper will address fracture related infections in trauma patients, looking at the bacteriology of these infections, its clinical implications and evolving nature.

Microbiota dysbiosis in odontogenic rhinosinusitis and its association with anaerobic bacteria

Odontogenic rhinosinusitis is a subtype of rhinosinusitis associated with dental infection or dental procedures and has special bacteriologic features. Previous research on the bacteriologic features of odontogenic rhinosinusitis has mainly used culture-dependent methods. The variation of microbiota between odontogenic and nonodontogenic rhinosinusitis as well as the interplay between the involved bacteria have not been explored. Therefore, we enrolled eight odontogenic rhinosinusitis cases and twenty nonodontogenic rhinosinusitis cases to analyze bacterial microbiota through 16S rRNA sequencing. Significant differences were revealed by the Shannon diversity index (Wilcoxon test p = 0.0003) and PERMANOVA test based on weighted UniFrac distance (Wilcoxon test p = 0.001) between odontogenic and nonodontogenic samples. Anaerobic bacteria such as Porphyromonas, Fusobacterium, and Prevotella were significantly dominant in the odontogenic rhinosinusitis group. Remarkably, a correlation between different bacteria was also revealed by Pearson's correlation. Staphylococcus was highly positively associated with Corynebacterium, whereas Fusobacterium was highly negatively correlated with Prophyromonas. According to our results, the microbiota in odontogenic rhinosinusitis, predominantly anaerobic bacteria, was significantly different from that in nonodontogenic rhinosinusitis, and the interplay between specific bacteria may a major cause of this subtype of rhinosinusitis.

Airway Epithelial Cell Junctions as Targets for Pathogens and Antimicrobial Therapy

Intercellular contacts between epithelial cells are established and maintained by the apical junctional complexes (AJCs). AJCs conserve cell polarity and build epithelial barriers to pathogens, inhaled allergens, and environmental particles in the respiratory tract. AJCs consist of tight junctions (TJs) and adherens junctions (AJs), which play a key role in maintaining the integrity of the airway barrier. Emerging evidence has shown that different microorganisms cause airway barrier dysfunction by targeting TJ and AJ proteins. This review discusses the pathophysiologic mechanisms by which several microorganisms (bacteria and viruses) lead to the disruption of AJCs in airway epithelial cells. We present recent progress in understanding signaling pathways involved in the formation and regulation of cell junctions. We also summarize the potential chemical inhibitors and pharmacological approaches to restore the integrity of the airway epithelial barrier. Understanding the AJCs-pathogen interactions and mechanisms by which microorganisms target the AJC and impair barrier function may further help design therapeutic innovations to treat these infections.

Functional and Immunological Studies Revealed a Second Superantigen Toxin in Staphylococcal Enterotoxin C Producing Staphylococcus aureus Strains

Staphylococcus aureus is a human and animal pathogen as well as a commensal bacterium. It can be a causative agent of severe, life-threatening infections with high mortality, e.g., toxic shock syndrome, septic shock, and multi-organ failure. S. aureus strains secrete a number of toxins. Exotoxins/enterotoxins are considered important in the pathogenesis of the above-mentioned conditions. Exotoxins, e.g., superantigen toxins, cause uncontrolled and polyclonal T cell activation and unregulated activation of inflammatory cytokines. Here we show the importance of genomic analysis of infectious strains in order to identify disease-causing exotoxins. Further, we show through functional analysis of superantigenic properties of staphylococcal exotoxins that even very small amounts of a putative superantigenic contaminant can have a significant mitogenic effect. The results show expression and production of two distinct staphylococcal exotoxins, SEC and SEL, in several strains from clinical isolates. Antibodies against both toxins are required to neutralise the superantigenic activity of staphylococcal supernatants and purified staphylococcal toxins.

The Frequency of Occurrence of Resistance and Genes Involved in the Process of Adhesion and Accumulation of Biofilm in Staphylococcus aureus Strains Isolated from Tracheostomy Tubes

Background: Bacterial biofilm on the surface of tracheostomy tubes (TTs) is a potential reservoir of potentially pathogenic bacteria, including S. aureus. For this reason, our study aimed to investigate biofilm production in vitro and the presence of icaAD and MSCRAMM genes in clinical S. aureus strains derived from TTs, with respect to antibiotic resistance and genetic variability. Methods: The clonality of the S. aureus strains was analyzed by the PFGE method. The assessment of drug resistance was based on the EUCAST recommendations. The isolates were evaluated for biofilm production by the microtiter plate method and the slime-forming ability was tested on Congo red agar (CRA). The presence of icaAD genes was investigated by PCR and MSCRAMM genes were detected by multiplex PCR. Results: A total of 60 patients were enrolled in the study. One TT was obtained from each patient (n = 60). Twenty-one TTs (35%) were colonized with S. aureus. A total of 24 strains were isolated as 3 patients showed colonization with 2 SA clones (as confirmed by PFGE). PFGE showed twenty-two unique molecular profiles. Two isolates (8%) turned out to be MRSA, but 50% were resistant to chloramphenicol, 25% to erythromycin and 8% to clindamycin (two cMLS_B and four iMLS_B phenotypes were detected). The microtiter plate method with crystal violet confirmed that 96% of the strains were biofilm formers. Representative strains were visualized by SEM. All isolates had clfAB, fnbA, ebpS and icaAD. Different MSCRAMM gene combinations were observed. Conclusions: the present study showed that the S. aureus isolated from the TTs has a high diversity of genotypes, a high level of antibiotic resistance and ability to produce biofilm.

Antimicrobial Resistance and Molecular Epidemiology of Staphylococcus aureus from Hunters and Hunting Dogs

Several studies have showed that a dog-to-human transmission of Staphylococcus aureus occurs. Hunting dogs do not have as much contact with their owners as dogs that live in the same household as the owners; however, these dogs have contact with their owners during hunting activities as well as when hunting game; therefore, we aimed to isolate S. aureus from hunters and their hunting dogs to investigate a possible S. aureus transmission. Nose and mouth samples were collected from 30 hunters and their 78 hunting dogs for staphylococcal isolation. The species identification was performed using MALDI-TOF. The antimicrobial susceptibility profiles were accessed using the Kirby-Bauer method and respective antimicrobial resistance genes were investigated by PCR. Multilocus sequence typing (MLST) and spa- and agr-typing was performed in all S. aureus isolates. S. aureus were detected in 10 (30%) human samples and in 11 (15.4%) dog samples of which 11 and 5 were methicillin-resistant S. aureus (MRSA). Other staphylococci were identified, particularly, S. pseudintermedius. Most S. aureus isolates were resistant to penicillin, erythromycin, and tetracycline. Evidence of a possible transmission of S. aureus between human and dogs was detected in three hunters and their dogs. S. aureus isolates were ascribed to 10 STs and 9 spa-types. A moderate colonization of S. aureus in hunting dogs and their owners was detected in this study. A few dog-to-dog and dog-to-human possible transmissions were identified.

Antimicrobial Resistance and Clonal Lineages of Staphylococcus aureus from Cattle, Their Handlers, and Their Surroundings: A Cross-Sectional Study from the One Health Perspective

Staphylococcus aureus have been progressively identified in farm animals and in humans with direct contact with these animals showing that S. aureus may be a major zoonotic pathogen. Therefore, we aimed to isolate S. aureus from cows, their handlers, and their immediate surroundings, and to investigate the antimicrobial resistance and genetic lineages of the isolates. Mouth and nose swabs of 244 healthy cows (195 Maronesa, 11 Holstein-Friesians, and 28 crossbreeds), 82 farm workers, 53 water and 63 soil samples were collected. Identification of species was carried out by MALDI-TOF MS Biotyper. The presence of antimicrobial resistance genes and virulence factors was assessed based on gene search by PCR. All isolates were typed by multilocus sequence typing and spa-typing. From 442 samples, 33 (13.9%), 24 (29.3%), 1 (2%), and 1 (2%) S. aureus were recovered from cows, farm workers, water, and soil samples, respectively. Most of the isolates showed resistance only to penicillin. S. aureus isolates were ascribed to 17 sequence types (STs) and 26 spa-types. Some clonal lineages were common to both cows and farm workers such as ST30-t9413, ST72-t148, and ST45-t350. Through a One Health approach, this study revealed that there is a great diversity of clonal lineages of S. aureus in cows and their handlers. Furthermore, some S. aureus lineages are common to cows and handlers, which may suggest a possible transmission.

Effect of Surface Tooling Techniques of Medical Titanium Implants on Bacterial Biofilm Formation In Vitro

The aim of this study was to assess the biofilm formation of Streptococcus mutans, Staphylococcus aureus, Enterococcus faecalis, and Escherichia coli on titanium implants with CAD-CAM tooling techniques. Twenty specimens of titanium were studied: Titanium grade 2 tooled with a Planmeca CAD-CAM milling device (TiGrade 2), Ti6Al4V grade 5 as it comes from CAD-DMLS device (computer aided design-direct metal laser sintering device) (TiGrade 5), Ti6Al4V grade 23 as it comes from a CAD-CAM milling device (TiGrade 23), and CAD-DMLS TiGrade 5 polished with an abrasive disc (TiGrade 5 polished). Bacterial adhesion on the implants was completed with and without saliva treatment to mimic both extraoral and intraoral surgical methods of implant placement. Five specimens/implant types were used in the bacterial adhesion experiments. Autoclaved implant specimens were placed in petri plates and immersed in saliva solution for 30 min at room temperature and then washed 3×with 1 ×PBS. Bacterial suspensions of each strain were made and added to the specimens after saliva treatment. Biofilm was allowed to form for 24 h at 37 °C and the adhered bacteria was calculated. Tooling techniques had an insignificant effect on the bacterial adhesion by all the bacterial strains studied. However, there was a significant difference in biofilm formation between the saliva-treated and non-saliva-treated implants. Saliva contamination enhanced S. mutans, S. aureus, and E. faecalis adhesion in all material types studied. S. aureus was found to be the most adherent strain in the saliva-treated group, whereas E. coli was the most adherent strain in the non-saliva-treated group. In conclusion, CAD-CAM tooling techniques have little effect on bacterial adhesion. Saliva coating enhances the biofilm formation; therefore, saliva contamination of the implant must be minimized during implant placement. Further extensive studies are needed to evaluate the effects of surface treatments of the titanium implant on soft tissue response and to prevent the factors causing implant infection and failure.

Drug Resistance and Epigenetic Modulatory Potential of Epigallocatechin-3-Gallate Against Staphylococcus aureus

Antimicrobial resistance of human pathogens, such as methicillin-resistant Staphylococcus aureus, is described by the World Health Organization as a health global challenge and efforts must be made for the discovery of new effective and safe compounds. This work aims to evaluate epigallocatechin-3-gallate (EGCG) epigenetic and modulatory drug potential against S. aureus in vitro and in vivo. S. aureus strains were isolated from commensal flora of healthy volunteers. Antibiotic susceptibility and synergistic assay were assessed through disk diffusion accordingly to EUCAST guidelines with and without co-exposure to EGCG at final concentrations of 250 µg/ml, 100 µg/ml, 50 µg/ml, and 25 µg/ml. Transcriptional expression of orfx, spdC, and WalKR was performed through qRT-PCR. A 90-day interventional study was performed with daily consumption of 225 mg of EGCG. Obtained data revealed a high prevalence of S. aureus colonization in healthcare workers and clearly demonstrated the antimicrobial and synergistic potential of EGCG as well as divergent resistant phenotypes associated with altered transcriptional expression of epigenetic and drug response modulators genes. Here, we demonstrate the potential of EGCG for antimicrobial treatment and/or therapeutic adjuvant against antibiotic-resistant microorganisms and report divergent patterns of epigenetic modulators expression associated with phenotypic resistance profiles.

Application of Metagenomic Next-Generation Sequencing in Mycobacterium tuberculosis Infection

The fight against Mycobacterium tuberculosis (MTB) has been going on for thousands of years, while it still poses a threat to human health. In addition to routine detections, metagenomic next-generation sequencing (mNGS) has begun to show presence as a comprehensive and hypothesis-free test. It can not only detect MTB without isolating specific pathogens but also suggest the co-infection pathogens or underlying tumor simultaneously, which is of benefit to assist in comprehensive clinical diagnosis. It also shows the potential to detect multiple drug resistance sites for precise treatment. However, considering the cost performance compared with conventional assays (especially Xpert MTB/RIF), mNGS seems to be overqualified for patients with mild and typical symptoms. Technology optimization of sequencing and analyzing should be conducted to improve the positive rate and broaden the applicable fields.

Molecular Characterization of Staphylococcus aureus Strains Isolated from Mobile Phones

The widespread use of mobile phones (MP) among healthcare personnel might be considered as an important source of contamination. One of the most pathogenic bacteria to humans is Staphylococcus aureus, which can be transmitted through the constant use of MP. Nevertheless, which specific type of strains are transmitted and which are their sources have not been sufficiently studied. The aim of this study is to determine the source of contamination of MP and characterize the corresponding genotypic and phenotypic properties of the strains found. Nose, pharynx, and MP samples were taken from a group of health science students. We were able to determinate the clonality of the isolated strains by pulsed-field gel electrophoresis (PFGE) and spa gene typing (spa-type). Adhesin and toxin genes were detected, and the capacity of biofilm formation was determined. Several of the MP exhibited strains of S. aureus present in the nose and/or pharynx of their owners. methicillin-susceptible Staphylococcus aureus (MSSA), hospital-acquired methicillin-resistant S. aureus (HA-MRSA), and community-acquired methicillin-resistant S. aureus (CA-MRSA) strains were found, which indicated a variety of genotypes. This study concludes that MP can be contaminated with the strains of S. aureus present in the nose and/or pharynx of the owners; these strains can be of different types and there is no dominant genotype.

Human microbial dysbiosis as driver of gynecological malignancies

Gynecological cancers that affect female reproductive tract, remain at the top of the global cancer burden list with high relapse rate and mortality. Notwithstanding development of several novel therapeutic interventions including poly-ADP-ribose polymerase inhibitors, this family of malignancies remain deadly. The human microbiome project demonstrated that dysbiosis of health resident microflora is associated with several pathologies including malignancies of the female reproductive tract and detailed characterization of species variation and host-microbe interaction could provide clues for identification of early diagnostic biomarker, preventive and therapeutic interventions. Emerging evidence suggests that several microbial signatures are significantly associated with gynecological cancers. An increased population of Proteobacteria and Firmicutes followed by significantly reduced Lactobacilli are associated with lethal epithelial ovarian cancer. Similarly, a constant association of elevated level of Atopobium vaginae, Porphyromonas somerae, Micrococci and Gardnerella vaginalis are observed in endometrial and cervical cancers. Moreover, human papilloma virus infection significantly augments colonization of pathogenic microbes including Sneathia sanguinegens, Anaerococcus tetradius, and Peptostreptococcus anaerobius and drives carcinoma of the cervix. Interestingly, microbial dysbiosis in female reproductive tract modulates expression of several microbial and immune-responsive genes such as TLR-4, TLR-5, TLR-6 and NOD-1. Therefore, stringent investigation into the microbial dysbiosis and its underlying mechanism could provide valuable cues for identification of early diagnostic biomarker, preventive and therapeutic interventions against rogue gynecological malignancies.

Role of Implantable Drug Delivery Devices with Dual Platform Capabilities in the Prevention and Treatment of Bacterial Osteomyelitis

As medicine advances and physicians are able to provide patients with innovative solutions, including placement of temporary or permanent medical devices that drastically improve quality of life of the patient, there is the persistent, recurring problem of chronic bacterial infection, including osteomyelitis. Osteomyelitis can manifest as a result of traumatic or contaminated wounds or implant-associated infections. This bacterial infection can persist as a result of inadequate treatment regimens or the presence of biofilm on implanted medical devices. One strategy to mitigate these concerns is the use of implantable medical devices that simultaneously act as local drug delivery devices (DDDs). This classification of device has the potential to prevent or aid in clearing chronic bacterial infection by delivering effective doses of antibiotics to the area of interest and can be engineered to simultaneously aid in tissue regeneration. This review will provide a background on bacterial infection and current therapies as well as current and prospective implantable DDDs, with a particular emphasis on local DDDs to combat bacterial osteomyelitis.

First Report of Antimicrobial Susceptibility and Virulence Gene Characterization Associated with Staphylococcus aureus Carriage in Healthy Camels from Tunisia

Simple Summary

The one-humped camel (Camelus dromedarius) is an important livestock species and is present in more than 46 national entities, with 80% of the camel population inhabiting Africa. In these regions, the role of camels in the livestock economy is highly valuable and a part of this camel herd is valorized on national or international markets for meat production, live animal export or milk production. Even if camels are the species that is most adapted to the harsh conditions of arid/semi-arid rangelands, they can be susceptible to a high number of pathogens, including S. aureus. This latter is often associated with asymptomatic carriage but can also be responsible for several diseases, therefore causing considerable economical losses. Continued monitoring and control assume particular importance in containing the spread of the bacterium since it constitutes an important zoonotic disease.

Abstract

A total of 318 nasal and rectal swabs were collected from 159 apparently healthy camels (Camelus dromedarius) randomly selected from five regions in southern and central Tunisia and screened for Staphylococcus aureus carriage. Staphylococcus spp. were recovered from 152 of 159 camels studied (95.6%) and in total 258 swabs (81%) were positive. Among these isolates, 16 were coagulase positive Staphylococcus (CoPS) (6.2%) and were characterized by biochemical and molecular tests as S. aureus. These were isolated from 14 camels (8.8%) with co-carriage in nasal and rectal mucosa by two camels. All S. aureus isolates recovered were methicillin-susceptible Staphylococcus aureus (MSSA) and were characterized by spa typing and PFGE. Three different spa types were recovered: t729, t4013 and a spa type newly registered as t19687, which was the most common. PFGE analysis revealed seven different patterns and these were characterized by MLST, which revealed five different sequence types (ST6, ST88, ST3583 and two new sequences, ST6504 and ST6506). All isolates harbored different virulence genes, including hld, encoding delta hemolysin; lukE–lukD, encoding bicomponent leukotoxin LukE–LukD; the clfB gene, encoding clumping factor B; the laminin gene, encoding laminin-binding protein; and cap8, encoding capsule type 8. Fifteen isolates harbored hemolysin beta (hlb) and fourteen encoded hemolysin alpha (hla) and hemolysin G2 (hlg_v). Adhesin factors, including clfA and fnbB, were detected in five and four isolates respectively. Binding proteins, including collagen (cbp) and elastin-binding protein (ebp), were detected in two S. aureus isolates while fibrinogen-binding protein (fib) was identified in four isolates. This study provides the first set of genotyping data on the population structure and presence of toxin genes of S. aureus strains in Tunisian camels.

The Type VII Secretion System of Staphylococcus

The type VII protein secretion system (T7SS) of Staphylococcus aureus is encoded at the ess locus. T7 substrate recognition and protein transport are mediated by EssC, a membrane-bound multidomain ATPase. Four EssC sequence variants have been identified across S. aureus strains, each accompanied by a specific suite of substrate proteins. The ess genes are upregulated during persistent infection, and the secretion system contributes to virulence in disease models. It also plays a key role in intraspecies competition, secreting nuclease and membrane-depolarizing toxins that inhibit the growth of strains lacking neutralizing immunity proteins. A genomic survey indicates that the T7SS is widely conserved across staphylococci and is encoded in clusters that contain diverse arrays of toxin and immunity genes. The presence of genomic islands encoding multiple immunity proteins in species such as Staphylococcus warneri that lack the T7SS points to a major role for the secretion system in bacterial antagonism. Expected final online publication date for the Annual Review of Microbiology, Volume 75 is October 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Recent progress in analyzing the spatial structure of the human microbiome: distinguishing biogeography and architecture in the oral and gut communities

Fueled by technological advances in methods for sample collection and preservation in sequencing studies, and in advances in computational analyses of high content image data, the spatial structure of the human microbiome is coming to light. In this mini-review, we summarize recent developments in our understanding of the structure of two human microbiomes: the lower gut and the oral cavity. We focus on only the most recent literature and we make an important distinction between two forms of spatial structure, governed by scale: biogeography and architecture. By segmenting the study of microbiome spatial structure into two categories, we demonstrate the potential to greatly advance our understanding of the mechanistic principles that link structure and function in the microbiome.

Staphylococcus aureus Responds to Physiologically Relevant Temperature Changes by Altering Its Global Transcript and Protein Profile

Staphylococcus aureus is an opportunistic pathogen that colonizes the anterior nares of 30 to 50% of the population. Colonization is most often asymptomatic; however, self-inoculation can give rise to potentially fatal infections of the deeper tissues and blood. Like all bacteria, S. aureus can sense and respond to environmental cues and modify gene expression to adapt to specific environmental conditions. The transition of S. aureus from the nares to the deeper tissues and blood is accompanied by changes in environmental conditions, such as nutrient availability, pH, and temperature. In this study, we perform transcriptomics and proteomics on S. aureus cultures growing at three physiologically relevant temperatures, 34°C (nares), 37°C (body), and 40°C (pyrexia), to determine if small scale, biologically meaningful alterations in temperature impact S. aureus gene expression. Results show that small but definite temperature changes elicit a large-scale restructuring of the S. aureus transcriptome and proteome in a manner that, most often, inversely correlates with increasing temperature. We also provide evidence that a large majority of these changes are modulated at the posttranscriptional level, possibly by sRNA regulatory elements. Phenotypic analyses were also performed to demonstrate that these changes have physiological relevance. Finally, we investigate the impact of temperature-dependent alterations in gene expression on S. aureus pathogenesis and demonstrate decreased intracellular invasion of S. aureus grown at 34°C. Collectively, our results demonstrate that small but biologically meaningful alterations in temperature influence S. aureus gene expression, a process that is likely a major contributor to the transition from a commensal to pathogen.

IMPORTANCE Enteric bacterial pathogens, like Escherichia coli, are known to experience large temperature differences as they are transmitted through the fecal oral route. This change in temperature has been demonstrated to influence bacterial gene expression and facilitate infection. Staphylococcus aureus is a human-associated pathogen that can live as a commensal on the skin and nares or cause invasive infections of the deeper tissues and blood. Factors influencing S. aureus nasal colonization are not fully understood; however, individuals colonized with S. aureus are at increased risk of invasive infections through self-inoculation. The transition of S. aureus from the nose (colonization) to the body (infection) is accompanied by a modest but definite temperature increase, from 34°C to 37°C. In this study, we investigate whether these host-associated small temperature changes can influence S. aureus gene expression. Results show widespread changes in the bacterial transcriptome and proteome at three physiologically relevant temperatures (34°C, 37°C, and 40°C).

The Expandables: Cracking the Staphylococcal Cell Wall for Expansion Microscopy

Expansion Microscopy (ExM) is a novel tool improving the resolution of fluorescence microscopy by linking the sample into a hydrogel that gets physically expanded in water. Previously, we have used ExM to visualize the intracellular Gram-negative pathogens Chlamydia trachomatis, Simkania negevensis, and Neisseria gonorrhoeae. Gram-positive bacteria have a rigid and thick cell wall that impedes classic expansion strategies. Here we developed an approach, which included a series of enzymatic treatments resulting in isotropic 4× expansion of the Gram-positive pathogen Staphylococcus aureus. We further demonstrate the suitability of the technique for imaging of planktonic bacteria as well as endocytosed, intracellular bacteria at a spatial resolution of approximately 60 nm with conventional confocal laser scanning microscopy.

Nasal microbiome research in ANCA-associated vasculitis: Strengths, limitations, and future directions

The human nasal microbiome is characterized by biodiversity and undergoes changes during the span of life. In granulomatosis with polyangiitis (GPA), the persistent nasal colonization by Staphylococcus aureus (S. aureus) assessed by culture-based detection methods has been associated with increased relapse frequency. Different research groups have characterized the nasal microbiome in patients with GPA and found that patients have a distinct nasal microbiome compared to controls, but the reported results between studies differed. In order to increase comparability, there is a need to standardize patient selection, sample preparation, and analytical methodology; particularly as low biomass samples like those obtained by nasal swabbing are impacted by reagent contamination. Optimization in obtaining a sample and processing with the inclusion of critical controls is needed for consistent comparative studies. Ongoing studies will analyze the nasal microbiome in GPA in a longitudinal way and the results will inform whether or not targeted antimicrobial management in a clinical trial should be pursued or not. This review focuses on the proposed role of S. aureus in GPA, the (healthy) nasal microbiome, findings in the first pilot studies in GPA, and will discuss future strategies.

Determinants of Staphylococcus aureus carriage in the developing infant nasal microbiome

BACKGROUND

Staphylococcus aureus is a leading cause of healthcare- and community-associated infections and can be difficult to treat due to antimicrobial resistance. About 30% of individuals carry S. aureus asymptomatically in their nares, a risk factor for later infection, and interactions with other species in the nasal microbiome likely modulate its carriage. It is thus important to identify ecological or functional genetic elements within the maternal or infant nasal microbiomes that influence S. aureus acquisition and retention in early life.

RESULTS

We recruited 36 mother-infant pairs and profiled a subset of monthly longitudinal nasal samples from the first year after birth using shotgun metagenomic sequencing. The infant nasal microbiome is highly variable, particularly within the first 2 months. It is weakly influenced by maternal nasal microbiome composition, but primarily shaped by developmental and external factors, such as daycare. Infants display distinctive patterns of S. aureus carriage, positively associated with Acinetobacter species, Streptococcus parasanguinis, Streptococcus salivarius, and Veillonella species and inversely associated with maternal Dolosigranulum pigrum. Furthermore, we identify a gene family, likely acting as a taxonomic marker for an unclassified species, that is significantly anti-correlated with S. aureus in infants and mothers. In gene content-based strain profiling, infant S. aureus strains are more similar to maternal strains.

CONCLUSIONS

This improved understanding of S. aureus colonization is an important first step toward the development of novel, ecological therapies for controlling S. aureus carriage.

Evaluation of the FilmArray® Pneumonia Plus Panel for Rapid Diagnosis of Hospital-Acquired Pneumonia in Intensive Care Unit Patients

The FilmArray^® Pneumonia plus Panel (FAPP) is a new multiplex molecular test for hospital-acquired pneumonia (HAP), which can rapidly detect 18 bacteria, 9 viruses, and 7 resistance genes. We aimed to compare the diagnosis performance of FAPP with conventional testing in 100 intensive care unit (ICU) patients who required mechanical ventilation, with clinically suspected HAP. A total of 237 samples [76 bronchoalveolar lavages (BAL_DS) and 82 endotracheal aspirates (ETA_DS) obtained at HAP diagnosis, and 79 ETA obtained during follow-up (ETA_TT)], were analyzed independently by routine microbiology testing and FAPP. 58 patients had paired BAL_DS and ETA_DS. The positivity thresholds of semi-quantified bacteria were 10³–10⁴ CFUs/mL or 10⁴ copies/mL for BAL, and 10⁵ CFUs/mL or copies/mL for ETA. Respiratory commensals (H. influenzae, S. aureus, E. coli, S. pneumoniae) were the most common pathogens. Discordant results for bacterial identification were observed in 33/76 (43.4%) BAL_DS and 36/82 (43.9%) ETA_DS, and in most cases, FAPP identified one supplemental bacteria (23/33 BAL_DS and 21/36 ETA_DS). An absence of growth, or polybacterial cultures, explained almost equally the majority of the non-detections in culture. No linear relationship was observed between bin and CFUs/mL variables. Concordant results between paired BAL_DS and ETA_DS were obtained in 46/58 (79.3%) patients with FAPP. One of the 17 resistance genes detected with FAPP (mecA/C and MREJ) was not confirmed by conventional testing. Overall, FAPP enhanced the positivity rate of diagnostic testing, with increased recognition of coinfections. Implementing this strategy may allow clinicians to make more timely and informed decisions.

Status of Biofilm-Forming Genes among Jordanian Nasal Carriers of Methicillin-Sensitive and Methicillin-Resistant Staphylococcus aureus

Introduction:

Biofilm formation in Staphylococcusaureus is a major virulence factor. Both MSSA and MRSA are common causes of community- and hospital-acquired infections and are associated with biofilm formation. The status of biofilm-forming genes has not been explored in Jordanian nasal carriers of S. aureus. This study investigates antibiotic resistance patterns and the prevalence of biofilm-forming genes between MSSA and MRSA in two distinct populations in Jordan.

Methods:

A total of 35 MSSA and 22 MRSA isolates were recovered from hospitalized patients and medical students at Prince Hamzah Hospital, Jordan. Antibiotic susceptibility was tested using disk diffusion method and Vitek 2 system. The phenotypic biofilm formation was tested using CRA and microtiter plate assays. The prevalence of the biofilm-forming genes was determined using multiplex PCR.

Results:

Among 57 S.aureus isolates, 22 (38.6%) isolates were MRSA and were highly resistant against benzylpenicillin, oxacillin, and imipenem. The frequencies of the icaADBC were 77.1%, 97.1%, 94.3%, and 97.1% respectively in MSSA compared to 86.4%, 100%, 100%, and 100% in MRSA isolates. On the other hand, the frequency of the fnbA, fnbB, clfA, fib, clfB, ebps, eno, and cna genes was 81.8%, 90.9%, 95.5%, 90.9%, 86.4%, 100%, 100%, and 40.9%, respectively in the MRSA isolates.

Conclusion:

In both groups, MRSA isolates, in comparison to MSSA, were significantly more resistant to cefoxitin, oxacillin, imipenem, tetracycline, clindamycin, and trimethoprim-sulfamethoxazole. Unexpectedly, biofilm formation and gene prevalence between MRSA and MSSA isolates showed no significant difference, suggesting other potential virulence mechanisms.

Staphylococcus aureus Osteomyelitis: Bone, Bugs, and Surgery

Osteomyelitis, or inflammation of bone, is most commonly caused by invasion of bacterial pathogens into the skeleton. Bacterial osteomyelitis is notoriously difficult to treat, in part because of the widespread antimicrobial resistance in the preeminent etiologic agent, the Gram-positive bacterium Staphylococcus aureus Bacterial osteomyelitis triggers pathological bone remodeling, which in turn leads to sequestration of infectious foci from innate immune effectors and systemically delivered antimicrobials. Treatment of osteomyelitis therefore typically consists of long courses of antibiotics in conjunction with surgical debridement of necrotic infected tissues. Even with these extreme measures, many patients go on to develop chronic infection or sustain disease comorbidities. A better mechanistic understanding of how bacteria invade, survive within, and trigger pathological remodeling of bone could therefore lead to new therapies aimed at prevention or treatment of osteomyelitis as well as amelioration of disease morbidity. In this minireview, we highlight recent developments in our understanding of how pathogens invade and survive within bone, how bacterial infection or resulting innate immune responses trigger changes in bone remodeling, and how model systems can be leveraged to identify new therapeutic targets. We review the current state of osteomyelitis epidemiology, diagnostics, and therapeutic guidelines to help direct future research in bacterial pathogenesis.

Comparative Analysis of Age- and Gender-Associated Microbiome in Lung Adenocarcinoma and Lung Squamous Cell Carcinoma

The intra-tumor microbiota has been increasingly implicated in cancer pathogenesis. In this study, we aimed to examine the microbiome in lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC) and determine its compositional differences with relation to age and gender. After grouping 497 LUAD and 433 LUSC patients by age and gender and removing potential contaminants, we identified differentially abundant microbes in each patient cohort vs. adjacent normal samples. We then correlated dysregulated microbes with patient survival rates, immune infiltration, immune and cancer pathways, and genomic alterations. We found that most age and gender cohorts in both LUAD and LUSC contained unique, significantly dysregulated microbes. For example, LUAD-associated Escherichia coli str. K-12 substr. W3110 was dysregulated in older female and male patients and correlated with both patient survival and genomic alterations. For LUSC, the most prominent bacterial species that we identified was Pseudomonas putida str. KT2440, which was uniquely associated with young LUSC male patients and immune infiltration. In conclusion, we found differentially abundant microbes implicated with age and gender that are also associated with genomic alterations and immune dysregulations. Further investigation should be conducted to determine the relationship between gender and age-associated microbes and the pathogenesis of lung cancer.

Molecular characteristics and antimicrobial susceptibility of Staphylococcus aureus among children with respiratory tract infections in southwest China

BACKGROUND

The molecular characteristics and antimicrobial susceptibility of Staphylococcus aureus (S. aureus) in general pediatric wards and county-level hospitals were rarely reported in China.

METHODS

Staphylococcus aureus was isolated from children hospitalized with respiratory tract infection (RTI) in Zhongjiang and Youyang counties in 2015. All isolates were typed by multilocus sequence, staphylococcal protein A, accessory gene regulator (agr), and staphylococcal cassette chromosome mec [SCCmec, for methicillin-resistant S. aureus (MRSA) only]. Polymerase chain reaction was used to screen 21 super-antigen (SAg) genes and panton-valentine leukocidin (pvl). Antimicrobial susceptibility testing was performed by E test.

RESULTS

A total of 2136 children were enrolled. Overall, 125 (5.9%) children carried S. aureus, among which MRSA accounted for 42.4%. ST59-SCCmec type IV-t437-agr group I (58.5%) was the most prevalent genotype in MRSA, and ST188-t189-agr group I (22.2%) was the top genotype in methicillin-sensitive S. aureus (MSSA). The pvl carriage rate in MRSA and MSSA was 15.1% and 9.7%, respectively (P = 0.4112). About 96.8% of S. aureus isolates were positive for at least one SAg gene. The most common SAg gene profile in the dominant ST59 clone was seb-sek-seq (42.8%). All S. aureus isolates were resistant to penicillin and erythromycin (minimum inhibitory concentration 90 was > 32 and 256 mg/L to penicillin and erythromycin, respectively), but usually susceptible to other tested non-β-lactam antimicrobials.

CONCLUSIONS

Staphylococcus aureus and MRSA were detected with a high frequency in children with RTI in county-level hospitals of China. ST59-SCCmec type IV-t437-agr group I was the dominant MRSA clone. The S. aureus isolates exhibited high resistance to penicillin and erythromycin.

[The problem of decolonization of Staphylococcus aureus nasal carriers from the microbiologist's point of view (review of literature).]

Staphylococcus aureus asymptomatically persists on the nasal mucosa, and also causes serious diseases in carriers (endogenous infection) and in patients in a hospital (nosocomial infection). Decolonization of nasal carriers of S. aureus is an important measure aimed at reducing the incidence of staphylococcal infections. Carriage is a form of nasal dysbiosis, therefore, the effectiveness of antibiotics for the decolonization of carriers, by definition, is low. The review discusses the prospects of using probiotics to restore the nasal microbiota. The commercial production of nasal probiotics has not yet been established, but developments in this direction are being carried out in different countries. The experimental substantiation of the possibility of using corynebacteria and other representatives of the nasal microbiota for the decolonization of staphylococcal carriers is presented, as well as the authors' ideas on how to improve the methods of microbial therapy. In particular, it was proposed to use biofilm probiotics, autoprobiotics, and autovaccines for this purpose.