Oral colonization of aerobic and facultatively anaerobic gram‐negative rods and cocci in irradiated,dentate, xerostomic individuals

This study aimed at investigating the oral colonization of aerobic and facultatively anaerobic gram‐negative rods and cocci in head‐ and neck‐irradiated, dentate, xerostomic individuals. Subjects were recruited from a nasopharyngeal carcinoma clinic and were segregated into group A: <60 years (n=25, 48±6 years, 5±5 years post‐irradiation) and group B: ≥60 years (n=8, 67±4 years, 2±2 years post‐irradiation) and were compared with age‐ and sex‐matched normal individuals, group C: <60 years (n=20, 44±12 years) and group D: ≥60 years (n=10, 70±3 years). Selective culture of the oral rinse samples was carried out to isolate, quantify and speciate (using API 20E kit) aerobic and facultatively anaerobic gram‐negative rods and cocci recovery. All test subjects were put under comprehensive oral and preventive care for 3 months, and 12 group A and 5 group B subjects were recalled for reassessment of aerobic and facultatively anaerobic gram‐negative rods and cocci colonization. All identical isolates, pre‐ and post‐hygienic care, were phenotypically (Vitek, Hazelwood, MA and antibiogram profile) and genotypically (pulsed‐field gel electrophoresis) evaluated. The aerobic and facultatively anaerobic gram‐negative rods and cocci isolated from the first round oral rinse samples included: Acinetobacter, Neisseria, Chryseomonas, Flavimonas, Pseudomonas, Citrobacter, Enterobacter, Escherichia, Klebsiella, Flavobacterium and Weeksella species. The aerobic and facultatively anaerobic gram‐negative rods and cocci isolation rate was high for irradiated individuals, and they were 64/25% and 100/80% for groups A/C and B/D, respectively. Recovery of aerobic and facultatively anaerobic gram‐negative rods and cocci and Klebsiella pneumoniae subsp. pneumoniae in oral rinse samples were found to be significantly more prevalent in the irradiated subjects (groups A and B). Enterobacteriaceae were more frequently isolated from oral rinse samples of aged irradiated subjects (group B vs D, P<0.05), where the quantity of Citrobacter freundii (colony‐forming units/ml oral rinse) was also significantly elevated. The isolation rate of aerobic and facultatively anaerobic gram‐negative rods and cocci after hygienic care remained unchanged; 3 of 12 and 3 of 5 of the recalled subjects from groups A and B, respectively, harbored same aerobic and facultatively anaerobic gram‐negative rods and cocci species. However, only two pairs of K. pneumoniae subsp. pneumoniae, sequentially isolated from same patients in group B, were found to be identical by pulsed‐field gel electrophoresis. This may be due to reinfection of the microbes from the same source or permanent colonization. In conclusion, irradiation‐induced xerostomia seems to favor frequent, repeated, transient intraoral colonization of aerobic and facultatively anaerobic gram‐negative rods and cocci.     

Oral colonisation by aerobic and facultatively anaerobic Gram-negative rods and yeast in Tibetans living in Lhasa

Sample groups of children (n=50) and adults (n=38) were selected from pools of 207 children, (11-13-year olds from two primary schools) and 94 adults (25-44-year olds from four governmental agencies) who were the subjects of an oral health survey among Tibetans living in Lhasa, Tibet Autonomous Region. Mean ages of the study groups of children (38% females) and adults (61% females) were 11.6+/-0.9 and 37.1+/-6.1 years, respectively. All had lived in Tibet since birth. Oral rinse samples were selective cultured to isolate, quantify and speciate aerobic and facultatively anaerobic Gram-negative rods (using the API 20E kit) and yeasts (using API 20C AUX and API ZYM kits). For children, the isolation rates for oral coliform bacteria and yeasts were 84 and 14%, respectively, for adults, the respective rates were 26 and 40%. The corresponding quantities of coliforms/yeasts for children and adults were 0.4+/-1.6 x 10(3)c.f.u./15.8+/-72.3 and 0.2+/-0.6 x 10(3)c.f.u./57.2+/-137.5c.f.u. per millilitre oral rinse, respectively. Aerobic and facultatively anaerobic Gram-negative rods and Stenotrophomonas maltophilia, a free-living saprophytic and ubiquitous bacterial species of wide geographic distribution, were significantly more frequently recovered from the children's oral rinses. The isolation rates of facultatively anaerobic Gram-negative rods in adults and yeasts in both groups were similar to those found in similar cohorts from southern China in earlier studies. Randomly amplified polymeric DNA analysis showed that the S. maltophilia spp. isolated from children were of several different clonal types and were school specific. This study shows that the colonisation rate of facultatively anaerobic Gram-negative rods in adults and yeasts in both groups are similar to those in populations living at lower altitudes, the native young, urban Tibetans appear to exhibit a high oral carriage rate of S. maltophilia spp.     

Oral health condition in southern Chinese after radiotherapy for nasopharyngeal carcinoma: extent and nature of the problem

OBJECTIVE: To measure the oral health status of southern Chinese nasopharyngeal carcinoma (NPC) survivors 1-4 years after radiotherapy. SUBJECTS AND METHODS: A total of 109 subjects participated in this cross-sectional study. Thirty-eight subjects were NPC survivors, 40 subjects were patients newly diagnosed with NPC and 31 were healthy subjects. Verified clinical examination techniques were used to assess limitation of jaw opening, the presence of mucositis, candidiasis, dental caries, periodontal disease [community periodontal index (CPI)] including attachment loss (ALoss) and prosthetic status/need. Differences among three groups were tested by chi-squared and Kruskal-Wallis tests. Relationships between selected clinical variables and radiation parameters were analysed using Spearman's rank correlation coefficients. RESULTS: The NPC survivors attended for dental treatment more frequently than the other groups (P < 0.01). NPC survivors had significant xerostomia (92%, P < 0.01), trismus (29%, P < 0.01), a higher prevalence of clinical candidiasis (24%, P < 0.01), a greater DMFT (16.4 +/- 7.0, P < 0.01), more decay/filled roots (2.1 +/- 2.9, P = 0.01) compared with new NPC patients and controls. No difference was found in CPI, ALoss, prosthetic status and need between groups. Dry mouth and tooth hypersensitivity were the most common oral problems perceived by the NPC survivors. CONCLUSION: Despite having regular dental follow-ups, oral health was compromised in NPC survivors 1-4 years postradiotherapy.     

The early colonization of gram-negative anaerobic bacteria in edentulous infants

The occurrence of oral gram-negative anaerobes was examined in 30 edentulous infants (mean age 3 months, range 1-7 months). One pooled swab sample from mucosal surfaces (cheeks, palate, tongue) and one saliva sample was taken from each infant. The samples were cultured aerobically and anaerobically using non-selective and selective media. Prevotella (Bacteroides) melaninogenica was the most frequently isolated anaerobe, found in 70% of the infants. The other common anaerobes were Fusobacterium nucleatum, Veillonella spp. and nonpigmented Prevotella (Bacteroides) spp., found in 60%, 57% and 57% of the infants, respectively. Of corroding bacilli, Bacteroides gracilis was detected in 23% of the infants, Wolinella spp. and microaerophilic Eikenella corrodens in one infant (3% each). Leptotrichia spp., microaerophilic Capnocytophaga spp., Prevotella (Bacteroides) loescheii and Prevotella (Bacteroides) intermedia were found in 17%, 13%, 13% and 7% of the infants, respectively. In addition to these 30 infants, 21 edentulous infants were investigated for the presence of Actinobacillus actinomycetemcomitans only. A. actinomycetemcomitans was not detected in any of the 51 edentulous infants. The number of different anaerobic bacterial species in the same mouth varied from 0 to 7. No anaerobic bacteria were detected in 3 of 30 children (10%). These data suggest that various anaerobic bacterial species readily colonize the edentulous mouth in infants.     

Identification, and susceptibility to seven antimicrobial agents, of 61 gram-negative anaerobic rods from periodontal pockets

Sixty-one cultures of Gram-negative anaerobic rods were isolated from deep periodontal pockets of patients with rapidly progressive periodontitis. Isolates were speciated as Bacteroides gingivalis (18 isolates), Bacteroides intermedius (8), Bacteroides oris (1), Bacteroides gracilis (17) and Fusobacterium nucleatum (17). Their susceptibilities, to seven antimicrobial agents, were determined in vitro using a plate dilution technique. Amoxycillin and amoxycillin with clavulanic acid were active against all isolates (MIC less than 1 mg/l) and proved the most effective agents tested. F. nucleatum and B. gracilis showed resistance to erythromycin; F. nucleatum had MIC values ranging from 0.03 mg/l up to 128 mg/l when tested with this, least effective agent. Metronidazole was effective against all isolates except for a few strains of B. gracilis (MIC less than 4 mg/l). Tetracycline hydrochloride and minocycline were active against all isolates except for a few strains of B. gracilis (MIC less than 2 mg/l with both minocycline and tetracycline hydrochloride). Penicillin proved less effective than amoxycillin with regard to inhibition of B. gracilis.     

An experimental study of the stability of irradiated teeth in the region of the dentinoenamel junction

Abstract In this in vitro study we investigated the influence of ionizing gamma rays on the stability in the region of the dentinoenamel junction. We removed the enamel on the labial surface of 30 incisors of bovines up to the dentinoenamel junction, so that a circular area of enamel with a diameter of 2.0 ± 0.1 mm was left and an enamel cylinder was created. 15 teeth were irradiated by a cobalt-60-source (energy dose 70 Gy). The other 15 teeth were used as controls. Using a material testing apparatus the shear bond strengths were measured by breaking off the enamel cylinders. Furthermore, the breaking modes were investigated in SEM. Comparing the results of the shear bond strength experiments, it was obvious that the stability in the region of the dentinoenamel junction was significantly less among the irradiated teeth than among the non-irradiated teeth. The median value of the gamma ray treated teeth was x?= 19.1 MPa and that of the non-ray-treated teeth was x?= 37.4 MPa. The non-irradiated teeth showed fractured surfaces only in dentin in 10 cases and in 5 cases in both dentin and enamel. In contrast to that, the irradiated teeth had fractured surfaces in 12 cases exclusively in dentin and only in 3 cases the enamel was also fractured. These results lead us to conclude that changes of biophysical property of teeth can be caused by the influence of ionizing rays.     

Oral colonization by anaerobic bacteria during childhood: role in health and disease

Anaerobes constitute a significant part of bacterial communities in human mouths. Their ability to colonize and survive in the environment, where remarkable changes occur during early childhood, is fundamental for oral homeostasis. However, relatively little is known of the time of colonization and succession of anaerobic species in the oral cavity. This article presents an up-to-date review on the development of the oral anaerobic microflora in respect to age, and in addition, considers some aspects of the role of oral anaerobes in health and disease.     

Relationship between oral gram-negative anaerobic bacteria in saliva of the mother and the colonization of her edentulous infant

Various gram-negative anaerobic bacterial species can be detected in the oral flora of edentulous infants. However, knowledge of the initial infection source is still scarce. Thirty Caucasian mothers (mean age 30 years) and their edentulous infants (mean age 3 months) were examined for the possible similarity of the oral gram-negative anaerobic flora. Paraffin-stimulated saliva was collected from the mothers. A pooled swab sample from mucosal surfaces and unstimulated saliva were collected from the infants. The samples were inoculated on nonselective and selective media and cultured aerobically and anaerobically. All of the 30 mothers harbored Fusobacterium nucleatum and 29 mothers Prevotella melaninogenica in their saliva. The salivary levels of P. melaninogenica, F. nucleatum, nonpigmented Prevotella spp., Prevotella intermedia and Prevotella loescheii exceeded 10(4) CFU/ml in about half of the 30 mothers. At this maternal salivary level, the infants' colonization frequency of P. melaninogenica and F. nucleatum was doubled. A positive correlation between maternal salivary concentration and infant's colonization was found for P. melaninogenica. No positive association was found with nonpigmented Prevotella spp., P. intermedia and P. loescheii. It can be speculated that maternal saliva may act as a source of some gram-negative anaerobes in the oral microflora of edentulous infants as early as before tooth eruption.     

Oral stereognosis in stroke and Parkinson's disease: a comparison of partially dentate and edentulous individuals

Oral stereognosis was measured in partially dentate and edentulous patients with stroke, Parkinson's disease, and an age and gender-matched control group. Stereognostic tests involving conventional free intra-oral manipulation of test objects were undertaken in the partially dentate and edentulous with and without complete dentures. Comparisons were made using the unpaired t-test and ANOVA. Edentulous stroke patients without dentures had significantly greater error scores and fewer correct identifications compared with partially dentate stroke patients. Stereognostic measures were similar in the partially dentate and edentulous with dentures, within experimental groups. In the partially dentate, there were no differences in stereognostic measures between the three groups. Stereognostic measures were poorer in edentulous stroke patients with and without dentures compared with the edentulous control group. Partially dentate stroke patients are less likely to have impaired oral stereognosis than edentulous stroke patients.     

Incidence of beta-lactamase production and antimicrobial susceptibility of anaerobic gram-negative rods isolated from pus specimens of orofacial odontogenic infections

The incidence of beta-lactamase production in anaerobic gram-negative rods isolated from 93 pus specimens of orofacial odontogenic infections and the antimicrobial susceptibility of these isolates against 11 antibiotics were determined. A total of 191 anaerobic gram-negative rods were isolated from the specimens. Beta-lactamase was detected in 35.6% of the black-pigmented Prevotella and 31.9% of the nonpigmented Prevotella. However, no strains among the other species isolated produced beta-lactamase. Ampicillin, cefazolin and cefotaxime showed decreased activity as regards beta-lactamase-positive Prevotella strains, whereas the activity of ampicillin/sulbactam, cefmetazole, and imipenem continued to be effective against such strains. All tested beta-lactam antibiotics were effective against Porphyromonas and Fusobacterium. Erythromycin showed decreased activity against nonpigmented Prevotella and Fusobacterium. Clindamycin, minocycline and metronidazole were powerful antibiotics against which anaerobic gram-negative rods could be tested. The present study showed that beta-lactamase-positive strains were found more frequently in the Prevotella strains than in any of the other species of anaerobic gram-negative rods. The effectiveness of adding sulbactam to ampicillin was demonstrated, as well as the difference in cephalosporin activity against beta-lactamase-positive strains.     

Oral health-related quality of life in southern Chinese following radiotherapy for nasopharyngeal carcinoma

Although the complications of head and neck radiotherapy in the treatment of nasopharyngeal carcinoma (NPC) have been described, there is limited information on the effect of oral complications on oral health related quality of life. The aim of this study was to describe the psychosocial and functional impact of oral conditions in southern Chinese following radiotherapy for NPC. A cross-sectional study design was used with a sample of 109 subjects including NPC survivors, newly diagnosed NPC cases and a control group. Oral health related quality of life was assessed through the SF-36 and the Oral Health Impact Profile measures and a dry mouth measure. Data on socio-demographic variables and treatment seeking were also collected. The psychosocial and functional impact of oral conditions as revealed by the health status measures was significantly greater in NPC survivors than newly diagnosed NPC cases and controls. The oral specific and condition specific measures appeared to discriminate more effectively between groups than the generic measure. NPC survivors sought significantly more dental treatment than the other groups. The oral complications of radiotherapy for NPC, notably sequelae of salivary gland damage, have a significant negative effect on oral health related quality of life and result in an increased burden of dental care in the long-term.     

In vitro activity of chlorhexidine against enteric rods, pseudomonads and acinetobacter from human periodontitis

Fifty-eight periodontal isolates of the families Enterobacteriaceae and Pseudomonadaceae, and the genera Acinetobacter and Achromobacter were studied to determine their susceptibility to Peridex (0.12% chlorhexidine digluconate solution; Procter & Gamble). In an agar dilution assay, about 50% of the study strains grew in the presence of 70 micrograms/ml of chlorhexidine. Enterobacter cloacae, Klebsiella pneumoniae, Pseudomonas aeruginosa, Pseudomonas cepacia, and Serratia marcescens comprised the most resistant species. Studies are needed to determine the microbiological and clinical effects of chlorhexidine usage in patients infected with enteric rods and pseudomonads.     

Clinical,microbiological and ultrastructural features of angular cheilitis lesions in Southern Chinese

OBJECTIVE: To obtain basetine data on angular cheilitis in Southern Chinese. DESIGN: A cross-sectional investigation of the clinical, microbiological and ultrastructural features of the condition. SUBJECTS AND METHOD: Thirty six Chinese adults with angular cheilitis; 28 controls matched for age and sex, with no inflammation. Clinical examination, swabs of lesions for microbiology, impressions of lesions for ultra-structure, using replica technique. MAIN OUTCOME MEASURES: Severity of lesions, associated signs and symptoms, incidence and type of microorganisms, ultrastructural features. RESULTS: Of a total 68 lesions 32 were bilateral and four unilateral. Forty four (65%) were mild (Type I) and the remaining 24 (35%) moderate (Type 11). Infective agents were isolated from 37 (54%) lesions; pure growth of Candida spp and Staph. aureus was noted in nine lesions each; a mixed growth of the two in I I, beta-haemolytic streptococci in three and a mixed flora including coliforms in the other five. Candida spp were present in one control, beta-haemolytic streptococci in two and coliforms in four others. Scanning etectron microscopy revealed natural topography of the angular skin with sparse colonisation by bacteria and yeasts. CONCLUSIONS: Angular cheilitis in Southern Chinese seems to be characterised by a milder clinical presentation and classic infective agents of the disease: Candida spp and Staph. aureus.     

Screening for subgingival occurrence of gram-negative enteric rods in periodontally diseased and healthy subjects

Objective

This study aimed to determine whether the variations in the occurrence of gram-negative enteric rods as detected through a longitudinal follow up with three consecutive visits, may be associated with the periodontal clinical status.

Design

Clinical and demographic parameters from 63 untreated chronic periodontitis (CP) subjects and 45 healthy controls (HC) were analyzed. Subgingival plaque samples were obtained from 6 sites in each subject at baseline, 1-week, and 1-month visits and processed using culture and biochemical tests. Culture findings were categorized taking into account the detection frequency of gram-negative enteric rods as persistent presence, transient presence, or absence of enteric rods in any sampling time.

Results

Although transient presence of gram-negative enteric rods was more prevalent in CP subjects (16.7%) than HC subjects (9.3%), the difference was not significant (P > 0.05). The majority of subjects showed a transient presence of gram-negative enteric rods at concentrations <2 × 10² CFU/mL. Persistent presence of gram-negative enteric rods was not observed in any subject through the entire study period. Moreover, differences in both the detection frequencies of individual species and the total number of gram-negative enteric rods were not statistically significant neither inter- nor intragroups.

Conclusion

The findings of the present study could indicate that gram-negative enteric rods are merely transient microorganisms within the subgingival environment and suggest that the periodontal clinical status appeared not to be influenced by the presence of these species.