Antibiotic-resistant oral streptococci in dental patients susceptible to infective endocarditis

Bacterial Quorum Sensing During Infection

Bacteria are highly interactive and possess an extraordinary repertoire of intercellular communication and social behaviors, including quorum sensing (QS). QS has been studied in detail at the molecular level, so mechanistic details are well understood in many species and are often involved in virulence. The use of different animal host models has demonstrated QS-dependent control of virulence determinants and virulence in several human pathogenic bacteria. QS also controls virulence in several plant pathogenic species. Despite the role QS plays in virulence during animal and plant laboratory-engineered infections, QS mutants are frequently isolated from natural infections, demonstrating that the function of QS during infection and its role in pathogenesis remain poorly understood and are fruitful areas for future research. We discuss the role of QS during infection in various organisms and highlight approaches to better understand QS during human infection. This is an important consideration in an era of growing antimicrobial resistance, when we are looking for new ways to target bacterial infections.

Methods of Biotyping of Streptococcus mutans Species with the Routine Test as a Prognostic Value in Early Childhood Caries

Purpose

In order to investigate the suitability of Streptococcus mutans species biotyping by measuring the activity of selected enzymes from a commercial test, criteria were established for biotyping clinical strains from children with dental caries. In addition, the relationships between the selected biotypes, sensitivity to commonly used antibiotics, and early childhood caries were determined.

Methods

A total of 142 S. mutans isolates from dental plaque of children with caries were divided into different biotypes. Patients were divided into two groups: noncavitated (1-2 in ICDAS) and cavitated (5-6 in ICDAS) lesions. Biotyping criteria were determined based on both the arbitrary method and the clusterization method. The susceptibility of the strains to amoxicillin, cefazolin, erythromycin, and teicoplanin was studied by diluting a solid medium.

Results

Biotype I was the most common. Mean MIC values showed that the strains belonging to biotypes II and IV were the most sensitive to amoxicillin. For predetermined biotypes, observed differences were dependent on the severity of dental caries.

Conclusions

The proposed method of S. mutans strains biotyping is relatively quick and simple to use, provided the application of suitable biotyping criteria, and may contribute to the effective prevention of dental caries induced by S. mutans.

Distribution of amoxicillin-resistant oral streptococci in dental plaque specimens obtained from Japanese children and adolescents at risk for infective endocarditis

BACKGROUND

Infective endocarditis (IE) is known to be a life-threatening disease and prevention of its onset is important. Oral amoxicillin (AMPC) is generally prescribed to patients at risk for IE prior to undergoing risky procedures, such as invasive dental treatments. We previously found that approximately 5% of systemically healthy Japanese subjects harbor strains highly resistant to AMPC. In the present study, the prevalence of strains in patients at risk for IE was investigated.

METHODS AND RESULTS

Thirty-four Japanese children and adolescents designated at risk for IE by their cardiovascular surgeons participated. Dental plaque specimens were obtained at recall examinations for dental checkups and placed in sterile phosphate-buffered saline, then diluted and streaked onto selective media for oral streptococci and also media containing AMPC. Nine strains with a minimum inhibitory concentration of AMPC of 16μg/mL or more were isolated from 7 of the subjects (20.6%), each of which was also resistant to other antibiotics analyzed except for new quinolone drugs. The 16S rRNA sequence of each strain demonstrated that all were oral streptococcal species. In addition, dental plaque specimens collected from 5 subjects after an additional interval of 3-4 months showed that 2 harbored the same clones at different time points.

CONCLUSIONS

These findings suggest a higher prevalence of AMPC-resistant strains in children and adolescents at risk for IE as compared to systemically healthy subjects. Thus, alternative antibiotics should be considered for such subjects when performing prophylaxis procedures.

Microbially-produced peptides having potential application to the prevention of dental caries

Strategies advanced to decrease the occurrence of dental caries have in the past typically focussed upon attempting to reduce plaque accumulation by application of broad-spectrum antibacterial agents. In recent years however there has been growing interest in the application of a more targeted approach to the selective elimination from plaque of those bacterial species that are specifically implicated as the aetiological agents of this disease. This review focuses upon a number of the small bacterially-produced peptide antibiotics known as bacteriocins that are currently being explored for their potential role in the treatment and prevention of dental caries.

Streptococcus salivarius bacteremia and spontaneous bacterial peritonitis in liver transplantation candidates

Bacterial infections are a serious complication of end-stage liver disease (ESLD) that occurs in 20% to 60% of patients. We retrospectively reviewed medical records of patients with ESLD who were identified by our microbiology laboratory as having Streptococcus salivarius bacteremia. Of 592 patients listed for transplantation between January 1998 and January 2006, 9 (1.5%) had 10 episodes of S salivarius bacteremia. Of 2 patients already receiving quinolone prophylaxis for spontaneous bacterial peritonitis (SBP), 1 later presented with a second episode. The male-to-female ratio was 1:1.2. Medians for age, Model for End-Stage Liver Disease score, and Child-Turcotte-Pugh score were 50 years, 17, and 10, respectively. Presenting symptoms and signs in 10 episodes of infection were ascites (in 8 episodes), elevated temperature (6), abdominal pain (5), and encephalopathy (4). Median laboratory values included: white blood cell count, 15.1 x 10(9)/L; creatinine, 0.9 mg/dL; albumin, 3.1 gm/dL; aspartate aminotransferase, 64 U/L; alanine aminotransferase, 52.5 U/L; ammonia, 67 mug/dL; and prothrombin time, 17.3 seconds. Ascitic fluid in patients with peritonitis showed a median white blood cell count of 466 cells/mm(3) (range, 250-12,822 cells/mm(3)), with 66% polymorphs, protein of 0.9 gm/dL, and albumin of 0.4 gm/dL. S salivarius may cause primary bacteremia and SBP in liver transplantation candidates despite quinolone prophylaxis.

Effect of the Diode Laser on Bacteremia Associated with Dental Ultrasonic Scaling: A Clinical and Microbiological Study

OBJECTIVE

The purpose of this study is to evaluate the potential use of diode lasers (DLs) to reduce bacteremia associated with ultrasonic scaling (US). Furthermore, the clinical efficacy of DLs as an adjunct to US in the treatment of gingivitis was investigated.

BACKGROUND DATA

Recently, lasers have found new applications in dental practice. The benefits of the use of DLs as an adjunct to US have not yet been determined.

METHODS

Twenty-two gingivitis patients were treated using a split-mouth study design in which each side was randomly treated by US alone or DL followed by US (DL + US). Blood samples were drawn just before and during US in each treatment step to detect induced bacteremia. Clinical parameters including plaque index, sulcus bleeding index, probing depth, and relative attachment level were recorded at baseline and 4 weeks postoperatively.

RESULTS

Bacteremia was detected in 15 patients (68%) after US alone, and in 8 patients following DL + US (36%). The reduction of the incidence of odontogenic bacteremia during US after the application of DL was statistically significant (p < 0.05). Clinical signs improved eventually, with no significant differences between the two treatment regimens (p > 0.05).

CONCLUSIONS

Application of DL energy can reduce bacteria in gingival crevices which may reduce bacteremia following US. The use of DL did not show additional clinical influence on gingival healing after treatment of gingivitis with US.

Intravenous antibiotic regimens and prophylaxis of odontogenic bacteraemia

OBJECTIVES

This study retrospectively examines the efficacy of prophylactic intravenous antibiotic regimens in the prevention of odontogenic bacteraemia in children with severe congenital heart defects receiving comprehensive dental treatment under general anaesthesia.

PATIENTS AND METHODS

Blood cultures were taken from children with congenital cardiac defects 30 seconds after completion of dental treatment under general anaesthesia. Antibiotic prophylaxis had been given intravenously immediately before dental treatment. The choice of antibiotics and the extent of dental treatment were recorded. The percentage prevalence of bacteraemia was compared with published data following multiple dental extractions using the same clinical and microbiological methodology.

RESULTS

The overall percentage prevalence of positive cultures in children receiving intravenous prophylactic antibiotics was 16%. The percentage of positive blood cultures in cardiac children who received ampicillin alone was not significantly different from that in children having a combination of amikacin and teicoplanin (16.7% v 22.2%) respectively [Chi Square = 0.385, df = 1, P= 0.535]. When compared with multiple extractions, both ampicillin alone and amikacin with teicoplanin were effective in reducing the prevalence of odontogenic bacteraemia.

CONCLUSIONS

In children with cardiac defects, bacteraemia after dental treatment is reduced by antibiotics but is still detected on 16% of occasions. In comparison with children receiving ampicillin alone, the combination of amikacin and teicoplanin is as effective in reducing bacteraemia in children who are either allergic to penicillins or who have received them within the previous month.

Comparison of lysis filtration and an automated blood culture system (BACTEC) for detection, quantification, and identification of odontogenic bacteremia in children

Lysis filtration (LyF) was compared with BACTEC PAEDS PLUS in estimating the prevalence of, and sensitivity for, detection of odontogenic bacteremia. Both real bacteremia and simulated bacteremia (seeded blood or saline samples) were assessed to determine the validity of LyF in estimating bacteremia. The simulated bacteremia was also used to assess the reliability of LyF to estimate intensity of bacteremia in CFU per milliliter of blood. Reference organisms were used to assess the abilities of LyF and BACTEC to isolate known oral streptococci. There was no difference in the number of CFU per milliliter of seeded saline, seeded blood, and drop cultures of the organisms plated directly onto agar. Blood cell volume had a negligible effect on the yield of organisms for simulated bacteremia. When LyF and BACTEC were compared, the time to detection of bacteremia was always significantly shorter for BACTEC. For aerobic cultures, these times were 43.7 and 9.6 h, respectively (P < 0.01). For anaerobic cultures, these times were 45.1 and 9.9 h, respectively (P < 0.01). These differences occurred as well for bacteremia following the extraction of a single tooth, with LyF and BACTEC aerobic cultures taking 78 and 30.5 h, respectively (P < 0.0001). For anaerobic cultures, the times were 90.8 and 45 h, respectively (P < 0.0004). A preextraction bacteremia was detected on 2.1% of occasions with BACTEC compared to 31% of occasions with LyF (P < 0.05) The use of LyF was an effective and reliable means of estimating the intensity of pre- and postextraction bacteremia. The values were 3.6 and 5.9 CFU/ml, respectively (P < 0.4729), and the difference was not statistically significant. In summary, BACTEC is quicker than LyF, but less sensitive. LyF provides additional important information in estimating the intensity of bacteremia.

Dental anxiety and the absorption of orally administered erythromycin stearate

Erythromycin stearate is an acid labile antibiotic, therefore fear and apprehension, which are known to affect gastric motility, may produce erratic absorption resulting in lower serum levels. The mean (SD) serum erythromycin concentration 75 minutes after a 1.5 gm oral dose of erythromycin stearate to 45 patients was 8.7 (4.8) mg/L and ranged widely from 0.4 to 20.5 mg/L. The serum concentration of erythromycin was below therapeutic levels (1.0 mg/L) in two patients. No significant association was found between anxiety and serum levels of erythromycin when age, gender, and gastric distress were taken into account. It is concluded that dental anxiety may indirectly influence the uptake of oral erythromycin stearate; but this relationship is complex, and there is no evidence from this study that increased dental anxiety decreases the uptake of the drug.

Prosthetic hip infection related to a dental procedure despite antibiotic prophylaxis

A 39-year-old man with systemic lupus erythematosus who was taking corticosteroids had a prosthetic hip infection with Streptococcus oralis after a dental procedure despite prophylaxis with erythromycin. The causative organism was resistant to erythromycin. For patients with prosthetic joints the literature does not support dental prophylaxis, which even if given appropriately, may fail to prevent infection. Some experts advocate giving antibiotic prophylaxis to patients at high risk, although data supporting this practice are limited. However, considering that most orthopedic surgeons and many dental clinicians provide antibiotic prophylaxis, alternatives to erythromycin such as a first-generation cephalosporin should be considered.

The prevention of infective endocarditis-paedodontic considerations. British Society for Antimicrobial Chemotherapy

This review of the literature considers the pathology and epidemiology of infective endocarditis (IE), dental procedures that may precipitate IE and prophylaxis against dentally induced IE. The most recent recommendations published in May 1992 by the British Society for Antimicrobial Chemotherapy are outlined and discussed.

Alpha-hemolytic streptococcal bacteremia: a review of 203 episodes during 1980-1991

This is a review of 203 episodes of alpha-hemolytic streptococcal bacteremia during a 12-year period (1980-91) in a large community teaching hospital in the USA. There were 87 male and 116 female patients, with ages ranging from newborn infants to a 96-year-old; 118 patients (58.1%) were 60 years or older. 31 patients had endocarditis, 93 had bacteremia, and 79 had polymicrobial bacteremia. Streptococcus sanguis, S. mitis, S. salivarius and S. intermedius accounted for 80% of the strains. Some strains were resistant to tetracycline, nafcillin, erythromycin or clindamycin. The overall mortality was 29.6% (60 of 203 patients). There was no significant difference in the mortality among patients with endocarditis, bacteremia, and polymicrobial bacteremia. Factors that adversely influenced the mortality rate were old age (60 years and older) and rapidly fatal or ultimately fatal underlying conditions.