Streptococcus mutans glutamate binding protein (GlnH) as antigen target for a mucosal anti-caries vaccine.

BACKGROUND: In recent years, several studies have demonstrated that bacterial ABC transporters present relevant antigen targets for the development of vaccines against bacteria such as Streptococcus pneumoniae and Enterococcus faecalis. In Streptococcus mutans, the glutamate transporter operon (glnH), encoding an ABC transporter, is associated with acid tolerance and represents an important virulence-associated factor for the development of dental caries. RESULTS: In this study, we generated a recombinant form of the S. mutans GlnH protein (rGlnH) in Bacillus subtilis. Mice immunized with this protein antigen elicited strong antigen-specific antibody responses after sublingual administration of a vaccine formulation containing a mucosal adjuvant, a non-toxic derivative of the heat-labile toxin (LTK63) originally produced by enterotoxigenic Escherichia coli (ETEC) strains. Serum anti-rGlnH antibodies reduced adhesion of S. mutans to the oral cavity of naïve mice. Moreover, mice actively immunized with rGlnH were partially protected from oral colonization after exposure to the S. mutans NG8 strain. CONCLUSIONS: Our results indicate that S. mutans rGlnH is a potential target antigen capable of inducing specific and protective antibody responses after immunization. Overall, these observations raise the prospect of the development of mucosal anti-caries vaccines.

LT adjuvant modulates epitope specificity and improves the efficacy of murine antibodies elicited by sublingual vaccination with the N-terminal domain of Streptococcus mutans P1.

In this study, we evaluated the immunogenicity, protective efficacy and peptide-based immune signatures of antibodies raised in mice after sublingual immunization with a recombinant form of the P1 (aka AgI/II, PAc) adhesin (P139-512) of Streptococcus mutans, a major etiological agent of dental caries. Sublingual administration of P139-512 in combination with the mucosal adjuvant LTK4R (a derivative of heat-labile LT toxin) induced strong and long-lasting systemic and mucosal immune responses. Incorporation of the adjuvant resulted in an enhancement of the anti-adhesive and anti-colonization activity against S. mutans as evaluated both under in vitro and in vivo conditions. Incorporation of the adjuvant to the vaccine formulation also changed the epitope specificity of the induced antibodies as determined by immunological signatures of sera collected from vaccinated mice. Use of a peptide microarray library led to the identification of peptide targets recognized by antibodies in serum samples with enhanced anti-adhesive effects. Altogether, the results presented herein showed that the sublingual administration of a P1-based subunit vaccine represents a promising approach for the prevention of dental caries caused by S. mutans. In addition, the present study disclosed the role of adjuvants on the epitope specificity and functionality of antibodies raised by subunit vaccines.

The occurrence and dissemination of methicillin and vancomycin-resistant Staphylococcus in samples from patients and health professionals of a university hospital in Recife, State of Pernambuco, Brazil.

INTRODUCTION: Methicillin-resistant Staphylococcus aureus (MRSA) strains have been responsible for many nosocomial outbreaks. Within hospitals, colonized employees often act as reservoirs for the spread of this organism. This study collected clinical samples of 91 patients admitted to the intensive care unit (ICU), hemodialysis/nephrology service and surgical clinic, and biological samples from the nasal cavities of 120 professionals working in those environments, of a University Hospital in Recife, in the State of Pernambuco, Brazil. The main objective of this study was to determine the occurrence and dissemination of methicillin- and vancomycin-resistant Staphylococcus spp. METHODS: The isolates obtained were tested for susceptibility to oxacillin and vancomycin and detection of the mecA gene. In addition, the isolates were evaluated for the presence of clones by ribotyping-polymerase chain reaction (PCR). RESULTS: MRSA occurrence, as detected by the presence of the mecA gene, was more prevalent among nursing technicians; 48.1% (13/27) and 40.7% (11/27) of the isolates were from health professionals of the surgical clinic. In patients, the most frequent occurrence of mecA-positive isolates was among the samples from catheter tips (33.3%; 3/9), obtained mostly from the hemodialysis/nephrology service. Eight vancomycin-resistant strains were found among the MRSA isolates through vancomycin screening. Based on the amplification patterns, 17 ribotypes were identified, with some distributed between patients and professionals. CONCLUSIONS: Despite the great diversity of clones, which makes it difficult to trace the source of the infection, knowledge of the molecular and phenotypic profiles of Staphylococcus samples can contribute towards guiding therapeutic approaches in the treatment and control of nosocomial infections.

The occurrence and dissemination of methicillin and vancomycin-resistant Staphylococcus in samples from patients and health professionals of a university hospital in Recife, State of Pernambuco, Brazil

Introduction Methicillin-resistant Staphylococcus aureus (MRSA) strains have been responsible for many nosocomial outbreaks. Within hospitals, colonized employees often act as reservoirs for the spread of this organism. This study collected clinical samples of 91 patients admitted to the intensive care unit (ICU), hemodialysis/nephrology service and surgical clinic, and biological samples from the nasal cavities of 120 professionals working in those environments, of a University Hospital in Recife, in the State of Pernambuco, Brazil. The main objective of this study was to determine the occurrence and dissemination of methicillin- and vancomycin-resistant Staphylococcus spp. Methods The isolates obtained were tested for susceptibility to oxacillin and vancomycin and detection of the mecA gene. In addition, the isolates were evaluated for the presence of clones by ribotyping-polymerase chain reaction (PCR). Results MRSA occurrence, as detected by the presence of the mecA gene, was more prevalent among nursing technicians; 48.1% (13/27) and 40.7% (11/27) of the isolates were from health professionals of the surgical clinic. In patients, the most frequent occurrence of mecA-positive isolates was among the samples from catheter tips (33.3%; 3/9), obtained mostly from the hemodialysis/nephrology service. Eight vancomycin-resistant strains were found among the MRSA isolates through vancomycin screening. Based on the amplification patterns, 17 ribotypes were identified, with some distributed between patients and professionals. Conclusions Despite the great diversity of clones, which makes it difficult to trace the source of the infection, knowledge of the molecular and phenotypic profiles of Staphylococcus samples can contribute towards guiding therapeutic approaches in the treatment and control of nosocomial infections. .

Antimicrobial resistance and detection of the mecA gene besides enterotoxin-encoding genes among coagulase-negative Staphylococci isolated from clam meat of Anomalocardia brasiliana.

The marine clam Anomalocardia brasiliana is a candidate as a sentinel animal to monitor the contamination levels of coliforms in shellfish-harvesting areas of Brazil's northeastern region. The aim of the present study was to search enterotoxin-encoding genes plus the mecA gene among coagulase-negative staphylococci (CNS) isolates from shellfish meats of A. brasiliana. The specimen clam (n=48; 40 clams per sample) was collected during low tide in the bay area of Mangue Seco from April through June 2009, and random samples of chilled and frozen shelled clam meat (n=33; 250 g per sample) were obtained from retail shops from January through March 2012. Seventy-nine CNS isolates were identified, including Staphylococcus xylosus, S. cohnii spp. urealyticus, S. sciuri, and S. lentus. A high percentage of isolates resistant to erythromycin (58.5%), penicillin (51.2%), and tetracycline (43.9%), and the fluoroquinolones levofloxacin (39%) and ciprofloxacin (34.1%) were recorded from those environmental samples. Isolates from retail shops were particularly resistant to oxacillin (55.3%) and penicillin (36.8%). All CNS resistant to oxacillin and/or cefoxitin were positive for the presence of the mecA gene, but phenotypically susceptible to vancomycin. Also, the enterotoxin-encoding genes seg and seh were detected through multiplex-polymerase chain reaction in 77.7% and 88.8% of the isolates from environmental samples, versus 90.5% and 100% of the isolates from retail shops, respectively. The data reveal the risk to public health due to consuming raw or undercooked shellfish containing enterotoxigenic plus methicillin-resistant CNS.