Prevalence of Eikenella corrodens in dental plaque

Clinical Presentation and Bacteriologic Analysis of Infected Human Bites in Patients Presenting to Emergency Departments

Previous studies of infected human bites have been limited by small numbers of patients and suboptimal microbiologic methodology. We conducted a multicenter prospective study of 50 patients with infected human bites. Seventy percent of the patients and assailants were young adult men. Fifty-six percent of injuries were clenched-fist injuries and 44% were occlusional bites. Most injuries were to the hands. Fifty-four percent of patients were hospitalized. The median number of isolates per wound culture was 4 (3 aerobes and 1 anaerobe); aerobes and anaerobes were isolated from 54% of wounds, aerobes alone were isolated from 44%, and anaerobes alone were isolated from 2%. Isolates included Streptococcus anginosus (52%), Staphylococcus aureus (30%), Eikenella corrodens (30%), Fusobacterium nucleatum (32%), and Prevotella melaninogenica (22%). Candida species were found in 8%. Fusobacterium, Peptostreptococcus, and Candida species were isolated more frequently from occlusional bites than from clenched-fist injuries. Many strains of Prevotella and S. aureus were beta-lactamase producers. Amoxicillin-clavulanic acid and moxifloxacin demonstrated excellent in vitro activity against common isolates.

In vitro activities of a new des-fluoroquinolone, BMS 284756, and seven other antimicrobial agents against 151 isolates of Eikenella corrodens

The des-fluoroquinolone BMS 284756 was active in vitro against all 151 clinical strains of Eikenella corrodens at a MIC of < or = 0.25 microg/ml and was comparable in activity to moxifloxacin and levofloxacin. The MIC at which 90% of the isolates were inhibited by penicillin G was 2 microg/ml; MICs for 8.6% of the strains (13 of 151) were > or = 4 microg/ml, including for two beta-lactamase-producing isolates. Amoxicillin-clavulanate and ampicillin-sulbactam inhibited all strains at a MIC of < or = 1 microg/ml.

Profile of subgingival microbiota in children with mixed dentition

A diversity of microbial species has been detected in children's oral flora at an early age. To investigate the composition of the subgingival microbiota of different groups of teeth in children with mixed dentition, 40 systemically healthy children, aged 7-8 years, randomly chosen, were examined. Subgingival plaque samples were taken from the mesiobuccal sites of 21, 41, 16 and 36 permanent teeth and 53, 73, 64 and 84 deciduous teeth. The samples were cultured for bacterial isolation anaerobically and in 10% CO2 plus air using selective and nonselective media. Forty-five different microbial species were isolated from both permanent and deciduous teeth. Streptococcus sanguis (79-70%), Streptococcus mitis (66-65%), Prevotella melaninogenica (51-57%), Eikenella corrodens (51-52%), Capnocytophaga gingivalis (46-34%), Capnocytophaga ochracea (45-45%), Actinomyces naeslundii (39-60%) and Prevotella intermedia (42-35%) were among the most frequently detected species in permanent and deciduous teeth respectively. Several suspected periodontal pathogens, such as Porphyromonas gingivalis, Prevotella loescheii, Campylobacter gracilis, Bacteroides forsythus, Campylobacter concisus, Peptostreptococcus micros and Selenomonas sputigena, albeit less frequently detected, were present in the microbiota of these children. The bacterial species Streptococcus constellatus, Peptostreptococcus micros, Pseudoramibacter alactolyticus, E. corrodens and Fusobacterium nucleatum were associated with non-bleeding permanent and deciduous teeth whereas Streptococcus intermedius, C. concisus, P. intermedia and P. loescheii were associated with bleeding.

Eikenella corrodens in human oral and non-oral infections: a review

There is substantial evidence in support of the existence of distinct clinical forms of human periodontal disease. Moreover, these different forms of periodontal disease may be associated with relatively distinct subgingival microflora, often involving microaerophilic or anaerobic Gram-negative bacterial species. Eikenella corrodens is a facultative Gram-negative bacillus which is a common inhabitant of the oral cavity and the intestinal and genital tracts. Its primary ecologic niche within the oral cavity appears to be dental plaque, both in periodontally healthy individuals and in periodontitis patients. However, E. corrodens is recognized as an infrequent human pathogen capable of causing extraoral infections, either as the sole infectious agent or as part of a mixed infection, its potential role in the etiology of periodontal disease is not well understood. E. corrodens is often present in the supra- and subgingival plaque of periodontally healthy subjects. On the basis of cross-sectional and longitudinal studies, E. corrodens appears to be somewhat more prevalent in subgingival plaque samples of periodontitis subjects than periodontally healthy individuals. However, the percentage of E. corrodens in the total cultivable microflora did not vary between the two groups. Microbiologic studies attempting to define the relationship between E. corrodens and periodontal disease assume that this species is essentially homogeneous and that all strains exhibit comparable pathogenic potential. However, E. corrodens exhibits 1) variable colony morphology, biochemical and serologic reactivity; 2) marked phenotypic diversity with respect to outer membrane protein and lipopolysaccharide structure; and 3) marked diversity in the restriction patterns of total genomic DNA. Thus, it is possible that a limited number of clones of E. corrodens may be associated with periodontal disease and/or extraoral infection, while other strains are relatively harmless commensals. Additional studies, possibly employing strain-specific nucleic acid probes, may be required to define the role of E. corrodens as a human periodontal pathogen.

Identification of a streptomycin resistance gene and a partial Tn3 transposon coding for a beta-lactamase in a periodontal strain of Eikenella corrodens

The beta-lactamase gene from a periodontal strain of Eikenella corrodens, resistant to penicillins and streptomycin, was inserted into pBGS9 and transformed into Escherichia coli DH5 alpha. A 4.7-kb insert of pJML1, one of the transformants, was partially sequenced and found to contain the right section of transposon Tn3 from the middle of the TnpR resolvase gene to the right inverted repeat RI(R), including the TEM-1 gene. Sequences identical to RSF1010 were found on either side of the Tn3 sequence. pJML1 also contained a streptomycin resistance gene, probably identical to that of RSF1010. A portion of the pJML1 insert was not homologous to either Tn3 or RSF1010 but was homologous to the chromosomal DNA of E. corrodens ATCC 23834. It is assumed that the insert of pJML1 was derived from the chromosomal DNA of E. corrodens EC-38.

Characterization of a beta-lactamase found in Eikenella corrodens

Eleven strains of Eikenella corrodens with beta-lactamase activity were isolated from a patient with refractory periodontitis who had previously been treated with penicillin antibiotics. These strains were relatively resistant to benzylpenicillin, amoxicillin, and ampicillin (MICs, greater than or equal to 64 micrograms/ml); susceptible to amoxicillin-clavulanate (2:1) (MICs, less than or equal to 4 micrograms/ml); and moderately susceptible to cephalothin and cephaloridine (MICs, 0.12 to 16 micrograms/ml). The addition of 1 microgram of potassium clavulanate, a beta-lactamase inhibitor, per ml resulted in a significant increase in the susceptibilities of these strains to penicillins but not to cephalosporins. Potassium clavulanate had no effect on non-beta-lactamase-producing strains. Enzyme production was constitutive since activity was not increased when cells were cultivated in the presence of benzylpenicillin. Enzyme activity was strongly inhibited by potassium clavulanate, sulbactam, and iodine; weakly inhibited by cloxacillin, imipenem, and moxalactam; but not inhibited by aztreonam, EDTA, or p-chloromercuribenzoate. By gel infiltration, the enzyme had an estimated molecular mass of 29 kDa. Isoelectric focusing of the partially purified enzyme gave a major beta-lactamase band at pH 5.50 and a minor band at pH 5.60. Plasmids were not detected in any of the 11 beta-lactamase-positive strains. This enzyme is considered to belong to class 2a of the Bush classification scheme.

DNA probe detection of Eikenella corrodens, Wolinella recta and Fusobacterium nucleatum in subgingival plaque

This cross-sectional study used species-specific DNA probes to examine subgingival plaque specimens for the presence of Eikenella corrodens, Wolinella recta, and Fusobacterium nucleatum in adults with untreated periodontitis or gingivitis and in healthy controls. W. recta and F. nucleatum were more prevalent in diseased sites from the periodontitis group when compared with the controls (81% vs 22% and 83% vs 20% respectively). E. corrodens was detected in 62% of the control sites and 81% of the periodontitis sites. Because the control sites commonly contained this organism, E. corrodens may not be useful in differentiating between health and disease. In addition, the relationship between the prevalence of W. recta and F. nucleatum and the prevalence of the established periodontal pathogens, Actinobacillus actinomycetemcomitans, Bacteroides intermedius and Bacteroides gingivalis, was examined. Positive detection of W. recta and F. nucleatum correlated closely with the presence of A. actinomycetemcomitans, B. intermedius and B. gingivalis. Therefore, W. recta and F. nucleatum do not appear to be unique indicators of periodontal disease.

Aerobic bacteria cultured from the mouth of the American opossum (Didelphis virginiana) with reference to bacteria associated with bite infections

The American opossum inflicts bite injuries both when hunted for food and when accidentally provoked when handled in captivity. This study involved aerobically culturing organisms from the mouths of seven wild opossums (Didelphis virginiana). Isolates included streptococci, coagulase-positive and -negative staphylococci, Aeromonas spp., Citrobacter freundii, Eikenella corrodens, and Escherichia coli.

Restriction endonuclease analysis of Eikenella corrodens

Eikenella corrodens is a gram-negative facultative bacillus commonly found in the oral cavity. Although the role of E. corrodens in periodonititis is not clear, its isolation from extraoral infections attests to its pathogenic potential. Previous studies suggested that this species is phenotypically diverse. In the present study, we used restriction endonuclease analysis (REA) to assess the genetic diversity of this species and to explore the applicability of REA in studying the transmission of E. corrodens. Two groups of E. corrodens isolates were used in this study. Group 1 included 47 epidemiologically independent isolates recovered from dental plaques in periodontally healthy subjects and periodontitis patients and from extraoral infections in different geographic areas. Group 2 E. corrodens included 40 isolates recovered from two periodontitis patients and two periodontally healthy subjects. The results indicated that E. corrodens is genetically heterogeneous, as determined by REA. The majority of the group 1 E. corrodens isolates exhibited strain-specific restriction patterns. Forty restriction patterns were distinguishable among the 47 isolates. Analyses of group 2 isolates revealed that three of four subjects harbored more than one clonal type of E. corrodens. In one instance, a periodontitis patient was found to be colonized by six different clones. Furthermore, two different clonal types of E. corrodens were recovered from a single periodontal pocket in this patient. The results indicated that REA may be a useful tool in the epidemiologic investigation of E. corrodens infections.

DNA homologies shared among E. corrodens isolates and other corroding bacilli from the oral cavity

In a previous microbiological study of Eikenella corrodens, we noted the presence of E. corrodens strains with variability in colony morphology, as well as other corroding bacilli phenotypically similar to E. corrodens but which were unidentifiable on the basis of biochemical reactions. This raised questions as to whether E. corrodens constitutes a genetically heterogeneous group of organisms, and whether the unidentified corroding bacilli represent atypical E. corrodens or genetically unrelated organisms. In the present study, the genetic relationship among 14 E. corrodens isolates and 6 unidentified corroding bacilli was examined. DNA base compositions were determined from the melting temperatures of DNA samples. DNA homologies among E. corrodens and corroding bacilli were determined by DNA hybridization in solution using S1 nuclease. The % G + C content of E. corrodens strains varied from 56 to 58%, and from 56 to 60% for unidentified corroding bacilli. The DNA homologies among 12 E. corrodens isolates and 2 reference strains varied from 57 to 97%. Although these E. corrodens isolates exhibited variabilities in colony morphology and biochemical profile, no subspecies was identified. The unidentified corroding bacilli shared less than 33% homology with either of the E. corrodens reference strains. These corroding bacilli were further divided into 3 species on the basis of DNA hybridization studies using radiolabeled DNA from 2 representative corroding bacilli. One of the unidentified corroding bacilli appears to be a component of the normal flora in the human oral cavity. Our results indicate that E. corrodens is a genetically homogeneous species containing no recognizable subspecies.(ABSTRACT TRUNCATED AT 250 WORDS)

Controversies in antibiotic choices for bite wounds

In the last decade much progress has been made in our understanding of animal bites. Two major areas of remaining controversy are discussed. Recent study of human bites has shown that the early literature depicting all human bites as having an extraordinarily high infection and complication rate was biased by its emphasis on human bites of the hand that presented late with infection already present. These bites, the so-called closed-fist injuries (CFI), do indeed have a poor prognosis, but it may be as much due to their location and initial neglect as to the source of the injury. Human bites elsewhere do not seem to have any higher risk than animal bites, which have an infection rate of about 10%. Human bites of the face, lips, and ears are at very low risk for infection (less than 3%) if properly treated. The CFI should be identified early and aggressively irrigated and debrided (if possible). CFI wounds can be treated on an outpatient basis if uninfected and less than 24 hours old. The economical outpatient antibiotics of choice for CFI are penicillin plus dicloxacillin; the former is needed to cover Eikenella corrodens and the latter to cover Staphylococcus aureus, both common in these wounds. Diabetics with hand infection frequently have Gram-negative infection and may warrant parenteral aminoglycosides. Second- and third-generation cephalosporins are very effective but should be reserved for special situations due to their expense. Prophylactic antibiotics are not indicated for typical bite wounds, which are low risk. The choice of antibiotic (when needed) in other bite wounds is a matter of confusion, because the only scientific data available are in vitro sensitivities, which are a very poor and crude reflection of the clinical reality. Antibiotic effectiveness in vivo is dependent on a complex summation of absorption, tissue levels (not just serum levels), host immune defenses, and the interrelationships between bacterial species present. For dog bite wounds, dicloxacillin and cephalexin are both good choices because they cover most of the broad spectrum of infecting pathogens; dicloxacillin is significantly cheaper.(ABSTRACT TRUNCATED AT 400 WORDS)

Eikenella corrodens in human mouth flora

The incidence of Eikenella corrodens in the human mouth was studied in 229 individuals. Six (2.6%) had positive cultures. The incidence of positive cultures for the saliva group was 0.6% and for the tooth-scraping group it was 8.2%. When 11 isolates were tested against 33 antimicrobials by disc-agar diffusion, 82% were susceptible to penicillin, cephalothin, and cefoperazone. Susceptibility to the remaining second- and third-generation cephalosporins studied was 100%. We suggest that the use of a second- or third-generation cephalosporin only is appropriate empiric therapy for human bite injuries.

Early microbial colonization of permucosal implants in edentulous patients

In edentulous patients, the microbial colonization of permucosal implants of sintered hydroxyapatite was studied. Samples were taken from mucosa and dentures before insertion of implants and from supra- and subgingival sites two to 10 weeks after insertion. In total, five patients and 10 implants with clinically healthy peri-implant tissues were studied. The samples were investigated by dark-field microscopy and anaerobic culture. The supragingival plaque of the implants was dominated by Gram-positive cocci and rods, the subgingival plaque by Haemophilus spp. and Veillonella parvula. A group of bacteria was found specifically related to the implants: Actinomyces odontolyticus, Peptostreptococcus micros, Haemophilus actinomycetemcomitans, Eikenella corrodens, Capnocytophaga sputigena, and Leptotrichia buccalis. Black-pigmented Bacteroides was not found in any of the examined samples. Spirochetes were observed in denture plaque samples and in supragingival plaque of the implants. It is concluded that bacteria known as potential periodontal pathogens colonize the permucosal implants in the first weeks after insertion. The presence of these species seems to be dependent on the ecological factors provided by the artificial gingival crevice of the permucosal implants in the edentulous mouth.

Prevalence and microbiology of localized prepubertal periodontitis

Loss of crestal alveolar bone at primary teeth was ascertained radiographically in a dental school clinical population of 2264 children. 19 patients (0.84%) demonstrated distinct periodontal bone destruction around one or more primary teeth; in only 2 of these patients had periodontal disease been identified in previous clinical examinations. A microbiological study of 35 subgingival samples from 9 available patients revealed a high prevalence of black-pigmented Bacteroides spp., mainly Bacteroides intermedius. Actinobacillus actinomycetemcomitans and Capnocytophaga spp. were predominant organisms in some samples. The present data indicate that localized prepubertal periodontitis is more common than previously realized and is associated with bacteria generally regarded as major periodontal pathogens.

Suspected periodontopathic microorganisms and their oral habitats in young children

Samples of subgingival plaque from 67 children, 5-7 years of age, were examined for the presence of certain suspected periodontal pathogenic species using the conventional technique of anaerobic sonification, dilution and spiral plating. When this technique was compared with a direct plating procedure which involved no preliminary dispersion and dilution of plaque specimens, it was found that the direct method resulted in double the frequency of children in whom black-pigmented Bacteroides (BPB) were detected and a 10-times increase in the number of subjects harbouring Actinobacillus actinomycetemcomitans. Samples from the tongue, tonsils and saliva were also plated using the direct technique. BPB were detected less commonly in the plaque specimens (61.3% of children) than in saliva (89.5%), or on the tongue (86.6%) and tonsils (97.1%). Expressed as percentages of a pooled sample of the total BPB population, the most frequently detected species in plaque were Bacteroides intermedius (44.4%) and Bacteroides melaninogenicus (48.0%). The most prevalent isolate in all other oral sites was B. melaninogenicus. Expressed as percentages of children in whom BPB were detected, the most frequently isolated species from plaque using the conventional dilution technique was B. intermedius (21.3%), whereas other BPB species were present in fewer than 5% of children. Fusobacterium nucleatum and Capnocytophaga species were isolated most frequently from plaque but were also commonly detected in the various other oral sites.