Exploring <Emphasis Type="BoldItalic">Staphylococcus aureus</Emphasis> pathways to disease for vaccine development

Staphylococcus aureus is a commensal of the human skin or nares and a pathogen that frequently causes skin and soft tissue infections as well as bacteremia and sepsis. Recent efforts in understanding the molecular mechanisms of pathogenesis revealed key virulence strategies of S. aureus in host tissues: bacterial scavenging of iron, induction of coagulation pathways to promote staphylococcal agglutination in the vasculature, and suppression of innate and adaptive immune responses. Advances in all three areas have been explored for opportunities in vaccine design in an effort to identify the critical protective antigens of S. aureus. Human clinical trials with specific subunit vaccines have failed, yet provide important insights for the design of future trials that must address the current epidemic of S. aureus infections with drug-resistant isolates (MRSA, methicillin-resistant S. aureus).     

Neutrophils in innate host defense against <Emphasis Type="BoldItalic">Staphylococcus aureus</Emphasis> infections

Staphylococcus aureus has been an important human pathogen throughout history and is currently a leading cause of bacterial infections worldwide. S. aureus has the unique ability to cause a continuum of diseases, ranging from minor skin infections to fatal necrotizing pneumonia. Moreover, the emergence of highly virulent, drug-resistant strains such as methicillin-resistant S. aureus in both healthcare and community settings is a major therapeutic concern. Neutrophils are the most prominent cellular component of the innate immune system and provide an essential primary defense against bacterial pathogens such as S. aureus. Neutrophils are rapidly recruited to sites of infection where they bind and ingest invading S. aureus, and this process triggers potent oxidative and non-oxidative antimicrobial killing mechanisms that serve to limit pathogen survival and dissemination. S. aureus has evolved numerous mechanisms to evade host defense strategies employed by neutrophils, including the ability to modulate normal neutrophil turnover, a process critical to the resolution of acute inflammation. Here we provide an overview of the role of neutrophils in host defense against bacterial pathogens and discuss strategies employed by S. aureus to circumvent neutrophil function.     

<Emphasis Type="Italic">Staphylococcus aureus</Emphasis> and <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> co-infection is associated with cystic fibrosis-related diabetes and poor clinical outcomes

Cystic fibrosis-related diabetes (CFRD) patients suffer from accelerated rates of pulmonary decline compared to cystic fibrosis (CF) patients with normal glucose tolerance (NGT). However, the mechanisms underlying this difference are unknown. While CFRD is associated with increased respiratory infections, a link between infection and enhanced pulmonary dysfunction remains unclear. The development of glucose intolerance is spectral, resulting in impaired glucose tolerance (IGT) prior to the diagnosis of CFRD. Inclusion of IGT patients within the NGT group may diminish the ability to identify correlations with CFRD. With this in mind, this study aimed to determine if the association between CFRD and respiratory infections is correlated with pulmonary decline. Respiratory cultures from 234 CF patients with confirmed diagnosis of NGT or CFRD were analyzed to measure rates of infection, focusing on the two most prevalent bacteria in CF, Staphylococcus aureus and Pseudomonas aeruginosa. Infection status was correlated with pulmonary function and confounding clinical variables including age, gender, blood glucose levels, and CF transmembrane conductance regulator (CFTR) phenotype were considered in multivariate analyses. CFRD patients, particularly those with extremely high blood glucose levels, were more likely than NGT patients to be co-infected with S. aureus and P. aeruginosa, compared to infection with only one pathogen. Co-infection was associated with decreased lung function and increased frequency of pulmonary exacerbations, even after adjustment for confounding variables. Alterations in the microbial community composition, as opposed to the presence of a single pathogen, may account for greater pulmonary decline in CFRD patients.     

Rapid diagnosis of<Emphasis Type="Italic"> Staphylococcus aureus</Emphasis> bacteremia using <Emphasis Type="Italic">S. aureus</Emphasis> PNA FISH

In the study presented here, the performance of the S. aureus PNA FISH assay was evaluated using 285 blood cultures (from 104 patients) that had gram-positive cocci resembling staphylococci on Gram stain. The new molecular test is based on a fluorescence in situ hybridization assay using peptide nucleic acid probes targeting Staphylococcus aureus 16S rRNA and is designed for the rapid identification of Staphylococcus aureus directly from positive blood cultures. The sensitivity, specificity, and positive and negative predictive values of the S. aureus PNA FISH for the rapid identification of Staphylococcus aureus directly from positive blood culture bottles were 100, 99.4, 99.2 and 100%, respectively.     

Detection of <Emphasis Type="Italic">Helicobacter pylori</Emphasis>, <Emphasis Type="Italic">Enterococcus faecalis</Emphasis>, and <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> in the subgingival biofilm of HIV-infected subjects undergoing HAART with chronic periodontitis

This study compared the frequency of Helicobacter pylori, Enterococcus faecalis, and Pseudomonas aeruginosa in the subgingival microbiota of HIV-seropositive and HIV-seronegative subjects with periodontitis or clinically healthy periodontal tissues. Fifty-four subjects were distributed into two HIV-seropositive groups (chronic periodontitis [HCP = 13] and periodontal health [HH = 10]) and two HIV-seronegative groups (chronic periodontitis [CP = 17] and periodontal health [H = 14]). The detection of bacterial species was carried out by polymerase chain reaction (PCR). CP patients showed significantly more periodontal destruction, inflammation, and supragingival plaque than HCP patients (P < 0.05). All species were detected at a higher prevalence in CP and HCP than H individuals (P < 0.01). In the HIV groups, H. pylori was significantly more prevalent in periodontitis compared to healthy patients (P < 0.01). A higher frequency of E. faecalis and P. aeruginosa was observed in the subgingival biofilm of HH than H subjects (P < 0.01). Moreover, E. faecalis was detected significantly more often in HIV-seropositive compared to HIV-seronegative patients, regardless of periodontal status (P < 0.01). These data indicate that H. pylori is frequently detected in the subgingival microbiota of periodontitis subjects. In contrast, HIV-seropositive patients with either periodontitis or periodontal health present a high prevalence of E. faecalis.     

Concurrent <Emphasis Type="Italic">M. tuberculosis</Emphasis>, <Emphasis Type="Italic">Klebsiella pneumoniae</Emphasis>, and <Emphasis Type="Italic">Candida albicans</Emphasis> infection in liver metastasis of bowel carcinoma

We describe the case of a 62-year-old patient with fever and abdominal pain of the right upper quadrant with a known history of adenocarcinoma of the colon and presence of hepatic metastases. One of the liver lesions underwent aspiration, and pus was sent for microbiological testing. Cultures of the pus were positive for Klebsiella pneumoniae and Candida albicans and polymerase chain reaction for Mycobacterium tuberculosis was concurrently positive; the patient received treatment for all three pathogens and improved clinically. One may consider searching not only for the usual pathogens of liver abscesses (gram-negative bacteria, anaerobic bacteria and gram-positive bacteria), but in special cases might consider pursuing a more detailed search for coexistence of fungi and mycobacteria in patients with cancer.     

Development of a vaccine against <Emphasis Type="Italic">Staphylococcus aureus</Emphasis>

A vaccine to prevent infections caused by Staphylococcus aureus would have a tremendously beneficial impact on public health. In contrast to typical encapsulated bacterial pathogens, such as Streptococcus pneumoniae, H. influenzae, and Neisseria meningitides, the capsule of S. aureus is not clearly linked to strain virulence in vivo. Furthermore, it is not clear that natural infection caused by S. aureus induces a protective humoral immune response, as does infection caused by typical encapsulated bacteria. Finally, pure B cell or antibody deficiency, in either animal models or in patients, does not predispose to more frequent or more severe S. aureus infections, as it does for infections caused by typical encapsulated bacteria. Rather, primary immune mechanisms necessary for protection against S. aureus infections include professional phagocytes and T lymphocytes (Th17 cells, in particular) which upregulate phagocytic activity. Thus, it is not clear whether an antibody-mediated neutralization of S. aureus virulence factors should be the goal of vaccination. Rather, the selection of antigenic targets which induce potent T cell immune responses that react to the broadest possible array of S. aureus strains should be the focus of antigen selection. Of particular promise is the potential to select antigens which induce both humoral and T cell-mediated immunity in order to generate immune synergy against S. aureus infections. A single-antigen vaccine may achieve this immune synergy. However, multivalent antigens may be more likely to induce both humoral and T cell immunity and to induce protection against a broader array of S. aureus isolates. A number of candidate vaccines are in development, raising the promise that effective vaccines against S. aureus will become available in the not-so-distant future. Possible development programs for such vaccines are discussed.     

In vitro anthelmintic activity of the essential oils of <Emphasis Type="BoldItalic">Zanthoxylum zanthoxyloides</Emphasis> and <Emphasis Type="BoldItalic">Newbouldia laevis</Emphasis> against <Emphasis Type="BoldItalic">Strongyloides ratti</Emphasis>

The need for new anthelmintic with no chemical residues is becoming urgent. In a program aiming at the evaluation of plant as sources of new active molecules, the anthelmintic activities of the essential oils (EOs) obtained from either Zanthoxylum zanthoxyloides seeds or Newbouldia laevis leaves were evaluated against Strongyloides ratti by analyzing the results of two in vitro bioassays. These two plants and their tested parts were retained after an ethnopharmacology survey that confirmed their use by small-scale farmers for treatment of small ruminants affected by digestive helminths. The plants were harvested in Benin, and their EO were obtained by hydrodistillation. The EO yield of extraction was 0.65% (w/w) of for Z. zanthoxyloides seeds and 0.05% (w/w) for N. laevis. The chemical compositions of the two EOs were analyzed by gas chromatography coupled with mass spectrometry. The major constituents of the EO from Z. zanthoxyloides consisted of the following compounds: γ-terpinene (18 %), undecane (15 %), valencene (8.3 %), decanal (8.3 %), and 3-carene (6.7 %). In contrast, the major constituents of the EO from N. laevis leaves consisted of the following compounds: β-caryophyllene (36 %) and eugenol (5.8 %). An egg-hatching inhibition (EHI) assay was developed and a larval migration inhibition assay was used on S. ratti to examine the effects of the EOs and to evidence their inhibitory concentrations (IC₅₀ and IC₉₀) values on this nematode. Furthermore, the toxicity of the two EOs on Vero cell line was evaluated. When tested on S. ratti egg hatching, the two EOs resulted in similar IC₅₀ values (19.5 and 18.2 μg/ml for Z. zanthoxyloides and N. laevis, respectively), which were about sevenfold higher than that of the control (thiabendazole, IC₅₀ = 2.5 μg/ml). Larval migration was inhibited at similar concentrations for: Z. zanthoxyloides (IC₅₀ = 46 μg/ml), N. laevis (IC₅₀ = 51 μg/ml), and the control [levamisole (IC₅₀ = 36 μg/ml)]. No cytotoxicity was found on Vero cells because both EOs had IC₅₀ values higher than 50 μg/ml. Therefore, we have concluded that the EOs from two plants, used in folk medicine, may contain compounds with anthelmintic activity and could be used as improved traditional medicines or, at least, as food additives in a combined treatment for the control of helminth infections.     

<Emphasis Type="Italic">P</Emphasis>. <Emphasis Type="Italic">aeruginosa</Emphasis> Biofilms in CF Infection

Pseudomonas aeruginosa is an opportunistic pathogen of immunocompromised hosts. In cystic fibrosis (CF), P. aeruginosa causes acute and chronic lung infections that result in significant morbidity and mortality. P. aeruginosa possesses several traits that contribute to its ability to colonize and persist in acute and chronic infections. These include high resistance to antimicrobials, ability to form biofilms, plethora of virulence products, and metabolic versatility. In P. aeruginosa, a cell-to-cell communication process termed quorum sensing (QS) regulates many of these factors that contribute to its pathogenesis. Recent evidence suggests that the CF lung environment presents a specialized niche for P. aeruginosa. The relationship of P. aeruginosa QS, biofilm formation, and the CF lung environment is discussed.     

<Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis>: Characteristics of the biofilm process

In this review, we define the biofilm process as a type of intercellular bacterial communication. We present up-to-date data on the structure of the Pseudomonas aeruginosa biofilm matrix and genetic mechanisms regulating its formation, discuss processes involved in active or passive rejection of the biofilm bacteria that promotes their spreading and attaching to new surfaces, and stress the complexity and chain character of reactions associated with biofilm formation.     

Cranberry proanthocyanidins have anti-biofilm properties against <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis>

Background

Bacteria within a biofilm are phenotypically more resistant to antibiotics, desiccation, and the host immune system, making it an important virulence factor for many microbes. Cranberry juice has long been used to prevent infections of the urinary tract, which are often related to biofilm formation. Recent studies have found that the A-type proanthocyanidins from cranberries have anti-biofilm properties against Escherichia coli.

Methods

Using crystal violet biofilm staining, resazurin metabolism assays, and confocal imaging, we examined the ability of A-type proanthocyanidins (PACs) to disrupt the biofilm formation of Pseudomonas aeruginosa. We used mass spectrometry to analyze the proteomic effects of PAC treatment. We also performed synergy assays and in vitro and in vivo infections to determine whether PACs, alone and in combination with gentamicin, could contribute to the killing of P. aeruginosa and the survival of cell lines and G. mellonella.

Results

Cranberry PACs reduced P. aeruginosa swarming motility. Cranberry PACs significantly disrupted the biofilm formation of P. aeruginosa. Proteomics analysis revealed significantly different proteins expressed following PAC treatment. In addition, we found that PACs potentiated the antibiotic activity of gentamicin in an in vivo model of infection using G. mellonella.

Conclusions

Results suggest that A-type proanthocyanidins may be a useful therapeutic against the biofilm-mediated infections caused by P. aeruginosa and should be further tested.

     

CC398 <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> subpopulations in Belgian patients

Studies based on genome-wide single nucleotide polymorphisms (SNPs) supported the existence of two subpopulations in clonal complex (CC) 398 Staphylococcus aureus: an ancestral human-adapted clade (HC) and an animal-associated clade (AC). In this study, we have investigated the occurrence of genetic markers that allow discrimination of these subpopulations among CC398 isolates collected during 2014 to 2016 from human patients in Belgium. A collection of isolates was investigated by means of spa-typing and 16S-mecA-nuc PCR. CC398 isolates were classified as belonging to the human or the animal clade by using a canonical SNPs PCR and further studied by antimicrobial susceptibility and the presence of toxins, immune evasion cluster (IEC), and resistance genes. A total of 124 (7.8%) human isolates belonged to CC398. They were grouped into HC (n?=?58) or AC (n?=?66). The genes erm(T), pvl, chp, and scn were predominantly found in HC-CC398, while AC-CC398 isolates carried more frequently than the mecA, erm(C), tet(K), tet(M), and tet(L) genes. Different combinations of gene profiles were observed according to the clade. CC398 isolates from Belgian patients belonged to different subpopulations including typical HC and AC-isolates. Few HC-strains with mecA and AC-isolates harboring IEC were found. CC398 isolates from Belgian patients belonged to different subpopulations including typical HC and AC-isolates, as well as new emerging subpopulations that underline the ability of this lineage to acquire resistance and virulence genes. Further research is needed to evaluate the emergence of these subpopulations in the clinical setting.     

Recurrent necrotizing fasciitis caused by methicillin-resistant <Emphasis Type="Italic">Staphylococcus aureus</Emphasis>

Reported here is a rare case of recurrent necrotizing fasciitis due to methicillin-resistant Staphylococcus aureus (MRSA). A 46-year-old female with poorly controlled diabetes and chronic ingestion of steroid-containing medications was admitted for treatment of necrotizing fasciitis of the right thigh. Three months following hospital discharge she was readmitted with necrotizing fasciitis of the left hand. On both occasions, MRSA was isolated from tissue cultures obtained during surgical debridement. Patients who develop necrotizing fasciitis are predisposed to severe soft tissue infections due to associated comorbid conditions such as diabetes mellitus. Recurrent soft tissue infection in a patient with previous MRSA-related necrotizing fasciitis should therefore be treated with a high index of suspicion.     

Dalbavancin reduces biofilms of methicillin-resistant <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> (MRSA) and methicillin-resistant <Emphasis Type="Italic">Staphylococcus epidermidis</Emphasis> (MRSE)

Activity of dalbavancin against methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus epidermidis (MRSE) in biofilm was investigated and the microbicidal biofilm concentrations (MBC) were determined. Biofilms obtained from ten MRSA and ten MRSE bloodstream isolates, collected from patients in the General Hospital of Vienna between 2012 and 2015, were incubated with dalbavancin in trypticase soy broth (TSB) in serial dilution from 0.0625 mg/l to 256 mg/l using a microtiter plate biofilm model. The plates were incubated for 24 h at 37 ° C and 50% humidity. Biofilms were fixed with 2.5% glutaraldehyde and stained with crystal violet. Subsequently the optical density (OD₆₂₀) was used to measure the MBC, defined as the concentration of dalbavancin leading to a 50% reduction of biofilm. MBC for MRSA was 1 mg/l–4 mg/l (minimal inhibitory concentrations (MIC) 0.0312 mg/l–0.064 mg/l). MBC for MRSE was 2 mg/l–16 mg/l (MIC 0.023 mg/l–0.0625 mg/l). Dalbavancin successfully reduced MRSA and MRSE in biofilms, and therefore provides a promising option for the treatment of biofilm-associated infections.     

<Emphasis Type="BoldItalic">Odocoileus hemionus</Emphasis> deer adenovirus is related to the members of <Emphasis Type="BoldItalic">Atadenovirus</Emphasis> genus

Summary.  The Odocoileus hemionus deer adenovirus (OdAdV-1) causes systemic and local vasculitis and proves extremely lethal for mule deer. To characterize the virus, part of the genome flanking the fiber gene was cloned and sequenced. The sequence revealed two open-reading frames that mapped to pVIII hexon-associated protein precursor and fiber protein of several other adenoviruses. The highest amino acid homology for pVIII and fiber was found with the members of the proposed Atadenovirus genus: ovine adenovirus isolate 287 (OAdV-287), bovine adenovirus 4 (BAdV-4) and duck adenovirus 1 (DAdV-1). The homology with bovine adenovirus type 3 (BAdV-3) proved low. The E3 region was not found between the gene for pVIII and fiber. These data suggest that OdAdV-1 is a member of the Atadenovirus genus. Received March 16, 2001 Accepted November 22, 2001     

Bioactivity of essential oils of <Emphasis Type="BoldItalic">Zingiber officinalis</Emphasis> and <Emphasis Type="BoldItalic">Achyranthes aspera</Emphasis> against mosquitoes

Due to the global health problems associated with mosquito-borne diseases, over two million people primarily in the tropical countries are at risk. The widely and commonly used chemical method though effective, has some major disadvantages making insect control practically difficult. In view of the above, it is unavoidable to search for new molecules, which are eco-friendly, cheaper, and safer. The present study deals with evaluation of bioactive potential of two commonly occurring plants against mosquitoes presenting an alternative to the conventional chemical methods. Essential oils extracted by steam distillation from rhizome of Zingiber officinalis and leaf and stem of Achyranthes aspera were evaluated for larvicidal, attractant/repellent, and oviposition attractant/deterrent activity against two mosquito species viz. Aedes aegypti and Culex quinquefasciatus. The highest larvicidal activity, i.e., LC₅₀ = 154 ppm and LC₅₀ = 197 ppm for A. aegypti and C. quinquefasciatus, respectively was shown by Z. officinalis. This oil also offers 5-h protection at the concentration of 0.5 mg/cm2 from both mosquito species. The highest oviposition deterrence activity was exhibited by A. aspera stem oil, i.e., 100% and 85.71%, in case of A. aegypti and C. quinquefasciatus, respectively, at the concentration of 0.1%. These results reveal that both these oils have control potential against A. aegypti and C. quinquefasciatus.     

Genome-wide comparative chromosome maps of <Emphasis Type="Italic">Arvicola amphibius</Emphasis>, <Emphasis Type="Italic">Dicrostonyx torquatus</Emphasis>, and <Emphasis Type="Italic">Myodes rutilus</Emphasis>

The subfamily Arvicolinae consists of a great number of species with highly diversified karyotypes. In spite of the wide use of arvicolines in biological and medicine studies, the data on their karyotype structures are limited. Here, we made a set of painting probes from flow-sorted chromosomes of a male Palearctic collared lemming (Dicrostonyx torquatus, DTO). Together with the sets of painting probes made previously from the field vole (Microtus agrestis, MAG) and golden hamster (Mesocricetus auratus, MAU), we carried out a reciprocal chromosome painting between these three species. The three sets of probes were further hybridized onto the chromosomes of the Eurasian water vole (Arvicola amphibius) and northern red-backed vole (Myodes rutilus). We defined the diploid chromosome number in D. torquatus karyotype as 2n?=?45?+?Bs and showed that the system of sex chromosomes is X1X2Y1. The probes developed here provide a genomic tool-kit, which will help to investigate the evolutionary biology of the Arvicolinae rodents. Our results show that the syntenic association MAG1/17 is present not only in Arvicolinae but also in some species of Cricetinae; and thus, should not be considered as a cytogenetic signature for Arvicolinae. Although cytogenetic signature markers for the genera have not yet been found, our data provides insight into the likely ancestral karyotype of Arvicolinae. We conclude that the karyotypes of modern voles could have evolved from a common ancestral arvicoline karyotype (AAK) with 2n?=?56 mainly by centric fusions and fissions.     

Bacteremic Pneumococcal Cellulitis Compared with Bacteremic Cellulitis Caused by<Emphasis Type="Italic"> Staphylococcus aureus</Emphasis> and<Emphasis Type="Italic"> Streptococcus pyogenes</Emphasis>

In order to better characterize bacteremic cellulitis caused by Streptococcus pneumoniae, a review was conducted of 10 cases of bacteremic pneumococcal cellulitis, which represented 0.9% of all cases of pneumococcal bacteremia (n=1,076) and 3.2% of all cases of community-acquired bacteremic cellulitis (n=312) that occurred in the Hospital de Bellvitge, Barcelona, from 1984 to 2001. In addition to these 10 cases, 28 cases of bacteremic pneumococcal cellulitis from the literature (Medline 1975–2001) were reviewed. Pneumococcal cellulitis of the face, neck, and trunk was observed more frequently in patients with systemic lupus erythematosus and hematologic disorders, while pneumococcal cellulitis of the limbs was more common in patients with diabetes, alcoholism, and parenteral drug use. In the Hospital de Bellvitge group, bacteremic cellulitis due to Streptococcus pneumoniae was more frequently associated with severe underlying diseases than that due to Staphylococcus aureus or Streptococcus pyogenes (100%, 57%, and 72%, respectively; P=0.01). A concomitant extracutaneous focus of infection (e.g., respiratory tract infection) suggesting hematogenous spread with metastatic cellulitis was more frequent in patients with pneumococcal cellulitis, while a local cutaneous entry of microorganisms was feasible in most patients with Staphylococcus aureus or Streptococcus pyogenes cellulitis. The 30-day mortality was 10% in patients with pneumococcal cellulitis, 13% in patients with Staphylococcus aureus cellulitis, and 23% in patients with Streptococcus pyogenes cellulitis (P=0.3). Thus, bacteremic pneumococcal cellulitis is an unusual manifestation of pneumococcal disease and occurs mainly in patients with severe underlying diseases. In most cases, pneumococcal cellulitis has a different pathophysiologic mechanism than cellulitis caused by Staphylococcus aureus or Streptococcus pyogenes. This study was supported in part by a grant (FIS no. 97/0716) from the Fondo de Investigaciones Sanitarias, Spanish Pneumococcal Study Network G03/103, National Health Service, Madrid, Spain, and a grant from the Agencia d'Avaluacio de Tecnologia Medica, Generalitat de Catalunya, Barcelona, Spain