Analysis of the antimicrobial susceptibility of anaerobic bacteria isolated from endodontic infections in Brazil during a period of nine years

Influence of systemic antibiotic therapy on the development and progression of induced apical periodontitis in Wistar rats

The aim of this study was to investigate the influence of systemic antibiotic therapy on the development and progression of induced apical periodontitis (AP) in Wistar rats. Fifty-six rats were submitted to pulp exposure of the lower left first molar for the induction of AP. On the same day, intraperitoneal antibiotic therapy was administered once a day, for 15 days, until euthanasia. The groups were formed according to the different treatments (n = 8): C-control; GEN-treated with gentamicin (10 mg/Kg); AC-treated with amoxicillin (100 mg/Kg); MZ-treated with metronidazole (40 mg/Kg); AMP-treated with ampicillin (100 mg/Kg); AMC group-treated with amoxicillin + clavulanic acid (100 mg/kg); CLI-treated with clindamycin (60 mg/kg). After euthanasia, the jaws were collected and processed for (1) histological and histometric analysis using hematoxylin and eosin staining, (2) analysis of collagen fibers using Picrosirius Red staining and (3) bacteriological analysis using Brown-Brenn staining. The data were analyzed statistically (p < 0.05). AP induction was confirmed in all groups. The AMC group had the lower intensity of inflammatory infiltrate (p = 0.028) and less periapical bone resorption compared to control (p = 0.006). Regarding collagen maturation, PSR staining revealed a predominance of mature collagen fibers in all groups. The AC and AMC groups had the lower amount of mature fibers and the highest amount of immature fibers, compared to all other groups (p < 0.001). All groups showed bacterial contamination; however, the AC and AMC groups showed a lower extent of bacterial contamination compared to the control (p < 0.001). It can be concluded that systemic antibiotic therapy influences the development and progression of induced AP.

Antimicrobial resistance in patients with endodontic infections: A systematic scoping review of observational studies

The aim of this study was to assess the prevalence and proportions of antimicrobial-resistant species in patients with endodontic infections. A systematic scoping review of scientific evidence was accomplished involving different databases. Nine investigations were selected including 651 patients. Enterococcus faecalis was resistant to tetracycline (30%-70%), clindamycin (100%), erythromycin (10%-20%), ampicillin (9%) and azithromycin (60%). On the contrary, Prevotella spp., Fusobacterium spp., Peptostreptococcus spp. and Streptococcus spp. were resistant to penicillin, tetracycline, doxycycline, ciprofloxacin, amoxicillin, erythromycin, metronidazole and clindamycin in different proportions. Fusobacterium nucleatum showed high resistance to amoxicillin, amoxicillin plus clavulanate and erythromycin. Prevotella oralis presented a predisposition to augment its resistance to clindamycin over time. Tanerella forsythia exhibited resistance to ciprofloxacin and rifampicin. Lactococcus lactis presented robust resistance to cephalosporins, metronidazole, penicillin, amoxicillin and amoxicillin-clavulanic acid. It was observed high levels of resistance to antimicrobials that have been utilised in the local and systemic treatment of oral cavity infections.

Microbiota present in combined endodontic-periodontal diseases and its risks for endocarditis

INTRODUCTION

Infective endocarditis (IE) is an inflammatory disease usually caused by bacteria that enter the bloodstream and establish infections in the inner linings or valves of the heart, including blood vessels. Despite the availability of modern antimicrobial and surgical treatments, IE continues to cause substantial morbidity and mortality. Oral microbiota is considered one of the most significant risk factors for IE. The objective of this study was to evaluate the microbiota present in root canal (RC) and periodontal pocket (PP) clinical samples in cases with combined endo-periodontal lesions (EPL) to detect species related to IE using NGS.

METHODS

Microbial samples were collected from 15 RCs and their associated PPs, also from 05 RCs with vital pulp tissues (negative control, NC). Genomic studies associated with bioinformatics, combined with structuring of a database (genetic sequences of bacteria reported for infective endocarditis), allowed for the assessment of the microbial community at both sites. Functional prediction was conducted using PICRUSt2.

RESULTS

Parvimonas, Streptococcus, and Enterococcus were the major genera detected in the RCs and PPs. A total of 79, 96, and 11 species were identified in the RCs, PPs, and NCs, respectively. From them, a total of 34 species from RCs, 53 from PPs, and 2 from NCs were related to IE. Functional inference demonstrated that CR and PP microbiological profiles may not be the only risk factors for IE but may also be associated with systemic diseases, including myocarditis, human cytomegalovirus infection, bacterial invasion of epithelial cells, Huntington's disease, amyotrophic lateral sclerosis, and hypertrophic cardiomyopathy. Additionally, it was possible to predict antimicrobial resistance variants for broad-spectrum drugs, including ampicillin, tetracycline, and macrolides.

CONCLUSION

Microorganisms present in the combined EPL may not be the only risk factor for IE but also for systemic diseases. Antimicrobial resistance variants for broad-spectrum drugs were inferred based on PICRUSt-2. State-of-the-art sequencing combined with bioinformatics has proven to be a powerful tool for conducting studies on microbial communities and could considerably assist in the diagnosis of serious infections.

CLINICAL RELEVANCE

Few studies have investigated the microbiota in teeth compromised by combined endo-periodontal lesions (EPL), but none have correlated the microbiological findings to any systemic condition, particularly IE, using NGS techniques. In such cases, the presence of apical periodontitis and periodontal disease can increase IE risk in susceptible patients.

Antibiotic Resistance in Patients with Peri-Implantitis: A Systematic Scoping Review

The implementation of adjunctive antibiotics has been recommended for the therapy of peri-implantitis (PI). In this review, antibiotic resistance patterns in PI patients were assessed. A systematic scoping review of observational studies and trials was established in conjunction with the PRISMA extension for scoping reviews. The SCOPUS, PubMed/MEDLINE, EMBASE, SCIELO, Web of Science, and LILACS databases were reviewed along with the gray literature. The primary electronic examination produced 139 investigations. Finally, four observational studies met the selection criteria. These studies evaluated 214 implants in 168 patients. Porphyromonas gingivalis and Fusobacterium nucleatum mainly presented high resistance to tetracycline, metronidazole, and erythromycin in PI patients. Similarly, Aggregatibacter&nbsp;actinomycetemcomitans was also highly resistant to clindamycin and doxycycline. Other microorganisms such as Tannerella forsythia, Parvimonas micra, and Prevotella intermedia/nigrescens also presented significant levels of resistance to other antibiotics including amoxicillin, azithromycin, and moxifloxacin. However, most microorganisms did not show resistance to the combination amoxicillin metronidazole. Although the management of adjunctive antimicrobials in the therapy of PI is controversial, in this review, the resistance of relevant microorganisms to antibiotics used to treat PI, and usually prescribed in dentistry, was observed. Clinicians should consider the antibiotic resistance demonstrated in the treatment of PI patients and its public health consequences.

Detection of Streptococcus mutans in symptomatic and asymptomatic infected root canals

OBJECTIVES

To investigate the presence of Streptococcus mutans in root canals of symptomatic necrotic teeth (SNT) and their associated acute apical abscesses (AAA) and in the root canals of asymptomatic necrotic teeth (ANT). It also aimed to investigate the presence of the cnm and cbm genes in specimens that harbored S. mutans.

MATERIALS AND METHODS

DNA was extracted from samples collected from 10 patients presenting pulpal necrosis associated with radiographic evidence of apical periodontitis (ANT) and from 10 patients in need of endodontic therapy due to the presence of pulpal necrosis (SNT) and AAA. The control group consisted of 10 patients with teeth with normal vital pulp and requiring endodontic treatment for prosthetic reasons. The presence of S. mutans was detected by quantitative real-time-PCR (qPCR) using species-specific primers. Samples harboring S. mutans were further evaluated for the presence of CBP genes by qPCR as well.

RESULTS

All studied sites showed a high prevalence of S. mutans, except the control group. Specifically, 60% of ANT and 70% of AAA/SNT paired samples were positive for S. mutans. The cnm gene was detected positive for S. mutans only in ANT samples (66.6%). The cbm gene was not detected in any of the investigated sites.

CONCLUSIONS

S. mutans was found in high prevalence in both asymptomatic and symptomatic endodontic infections, including in abscesses, but it was not detected in the root canals of teeth with normal vital pulp. Interestingly, cnm+ S. mutans was only detected in asymptomatic/chronic primary endodontic infections associated with apical lesion. Therefore, it appears that cnm, and possibly other CBPs, may play an underestimated role in chronic endodontic infections.

CLINICAL RELEVANCE

A high prevalence of Streptococcus mutans cnm+ gene was detected only in asymptomatic primary endodontic infections associated with apical lesion. Therefore, it appears that this collagen-binding protein gene plays an underestimated role in asymptomatic/chronic endodontic infections.

Molecular characterization and antibacterial activity of oral antibiotics and copper nanoparticles against endodontic pathogens commonly related to health care-associated infections

OBJECTIVE

To carry out molecular characterization and determine the antibacterial activity of oral antibiotics and copper nanoparticles (Cu-NPs) against endodontic strains isolated from persistent infections.

MATERIALS AND METHODS

Root canal samples from 24 teeth in different patients with persistent endodontic infections were obtained. The isolated strains were identified by biochemical tests and 16S rDNA sequencing. Genotyping was achieved by molecular methods. The antibacterial activity of antibiotics and copper nanostructures was determined by using minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values. Furthermore, a time-kill kinetics assay was evaluated. Nonparametric tests (Kruskal-Wallis ANOVA) were performed (p value <0.05).

RESULTS

Twenty-one isolated strains were identified. Six isolates of Enterococcus faecalis were grouped into two clusters of three isolates each, two of which were clones. All were clarithromycin-resistant and erythromycin. Eight Pseudomonas putida presented two clusters, two Pseudomonas spp. were not clonal, and all were resistant to the tested antibiotics except tetracycline. Two of five strains of Cutibacterium acnes were clonal, and all were resistant only to metronidazole. The lowest MIC and MBC values were obtained with Cu-NPs. Time-kill kinetics using Cu-NPs showed a significant decrease in all tested species within 4 h and reached 100% in 2 h for C. acnes.

CONCLUSION

In this study, in relation to health care-associated infections, endodontic strains of each species isolated at least in one patient were polyclonal. In Pseudomonas spp., at least one clone was shared between patients. E. faecalis and C. acnes strains were susceptible to low Cu-NP concentrations, while Pseudomonas spp. strains were resistant.

CLINICAL RELEVANCE

Assessing and keeping track of the susceptibility of clinical strains to antimicrobial compounds is important for the clinical outcome. Based on our results, Cu-NPs could be an alternative for endodontic treatment, in order to avoid selection of resistant strains.

Prevention of infective endocarditis and bacterial resistance to antibiotics: A brief review

The purpose of this statement is to debate the recommendations of the American Heart Association (AHA) for the prevention of infective endocarditis through an antibiotic prophylaxis protocol and its relation with bacterial resistance to antibiotics. Since dental infections involve biofilms that include several bacterial species (Gram-negative and Gram-positive), it is essential, from the dental point of view, to consider the frequency, magnitude, and duration of bacteremia associated with active dental infections before applying antibiotic prophylaxis. The actual guidelines for antibiotic prophylaxis should be revised according to recent evidence of bacterial resistance. Amoxicillin/clavulanic acid and moxifloxacin should be considered due to their effectiveness against bacteria associated with oral, GU, and GI infections and the low rates of antibiotic resistance associated with these antibiotics, instead of the actual protocol, which includes amoxicillin (2 g) or clindamycin (600 mg) administered an hour before the dental procedures. The breaking point to test the antibiotic bacterial resistance (ABR) had a wide range in the different studies that were analyzed, which could explain the widely varied ABR percentages reported for the various antibiotics used for antibiotic prophylaxis.

Resistance profile to antimicrobial agents in the main circulating bacteria isolated from acute periodontal and endodontic infections in Latin America (MICROBE- DENT): A systematic review protocol

BACKGROUND

Antimicrobial resistance is currently considered the main risk to global health. A variety of microbial species have been isolated from endodontic and periodontal infections. However, clinical endodontic and periodontics bacterial isolates have not been sufficiently characterized with regard to their capacity for antibiotic resistance. We aim to assess the existing evidence to estimate the prevalence of the main antimicrobial resistance and multidrug resistant organisms in endodontics and periodontics and to describe their geographic distribution in Latin America.

METHODS

All types of designs and will be restricted to Latin American studies will be included in this systematic review. MEDLINE, Embase, CINAHL, BVS (LILACS, BBO - bvsalud.org), IBECS (bases.bireme.br), Google Scholar, Cochrane Central Register of Controlled Trials, and Web of Science databases will be searched from 2013 to December 31, 2018 for all types of study designs that report microbial infection in endodontics and periodontics and their resistance and that define the microbiological methods used to identify microorganisms. The selection of articles for inclusion will be performed by 2 reviewers using predefined eligibility criteria. The Cochrane and ROBINS-I risk of bias assessment tools will be used to assess the methodological quality of randomized control trials. The Newcastle-Ottawa scale will be used to assess the quality of methodology in observational studies. The overall quality of evidence will be assessed using Grading of Recommendations Assessment, Development and Evaluation (GRADE) using the same principles and domains applied in the quality assessment of prognostic studies. The heterogeneity of the findings will be assessed using both the χ test and the I statistic. Sensitivity analysis will be performed by subgroup analyses and meta-regression to investigate the effect of study-level characteristics, such as age, gender, and methodological quality score, whenever possible. Publication bias across studies will be evaluated by visual inspection of the funnel plots and Begg's test for the results covered in 10 or more studies.

RESULTS

The evidence derived by this study will inform best practices for patients with endodontic and periodontal problems receiving antimicrobial agents.

CONCLUSION

Successful completion will significantly impact clinical practice and contribute to improved prescribing competency.

PROTOCOL REGISTRATION

PROSPERO-CRD42018077810.

Antibiotic prescription for endodontic infections: a survey of Brazilian Endodontists

AIM

To investigate antibiotic prescribing habits reported by Brazilian endodontists in specific clinical situations.

METHODOLOGY

Brazilian endodontists (n = 13 853) were invited to answer an online questionnaire. The questionnaire consisted of two parts: the first part contained personal data such as age, gender, years of experience and location of endodontic practice; the second part included questions regarding their behaviour when prescribing antibiotics in dental practice. The subjects provided their registration number in the Regional Council of Dentistry (RCD) to prevent duplication of data. Data were collected and analysed by SPSS 17.0 (SPSS, Inc., Chicago, IL, USA). Chi-square and Fisher's exact tests were used to test the significance of possible associations (P < 0.05).

RESULTS

From the 13 853 questionnaires, a total of 615 were answered (4.44%). The first-choice antibiotic was amoxicillin (81.5%), followed by amoxicillin + clavulanic acid (30.7%). For acute apical abscesses with intra- and extraoral diffuse swelling, fever and trismus, 90.1% reported they would prescribe antibiotics, whilst 88.1% reported they would prescribe antibiotics even without extraoral swelling, fever and trismus, and 20.5% would prescribe antibiotics in cases of chronic apical periodontitis, and sinus tract. The first-choice antibiotics varied by age of dentist (P < 0.001) and time elapsed since their endodontic graduation (P = 0.001).

CONCLUSIONS

Many endodontists reported prescribing antibiotics in situations where they would not be indicated. Likewise, the general administration of antibiotics was longer in duration than necessary, reinforcing the need of continuous education regarding the use of antibiotics.

Bacterial diversity of symptomatic primary endodontic infection by clonal analysis

The aim of this study was to explore the bacterial diversity of 10 root canals with acute apical abscess using clonal analysis. Samples were collected from 10 patients and submitted to bacterial DNA isolation, 16S rRNA gene amplification, cloning, and sequencing. A bacterial genomic library was constructed and bacterial diversity was estimated. The mean number of taxa per canal was 15, ranging from 11 to 21. A total of 689 clones were analyzed and 76 phylotypes identified, of which 47 (61.84%) were different species and 29 (38.15%) were taxa reported as yet-uncultivable or as yet-uncharacterized species. Prevotella spp., Fusobacterium nucleatum, Filifactor alocis, and Peptostreptococcus stomatis were the most frequently detected species, followed by Dialister invisus, Phocaeicola abscessus, the uncharacterized Lachnospiraceae oral clone, Porphyromonas spp., and Parvimonas micra. Eight phyla were detected and the most frequently identified taxa belonged to the phylum Firmicutes (43.5%), followed by Bacteroidetes (22.5%) and Proteobacteria (13.2%). No species was detected in all studied samples and some species were identified in only one case. It was concluded that acute primary endodontic infection is characterized by wide bacterial diversity and a high intersubject variability was observed. Anaerobic Gram-negative bacteria belonging to the phylum Firmicutes, followed by Bacteroidetes, were the most frequently detected microorganisms.

Antimicrobial Susceptibility and Characterization of Virulence Genes of Enterococcus faecalis Isolates from Teeth with Failure of the Endodontic Treatment

INTRODUCTION

The aim of this study was to investigate the prevalence of virulence factors and the antimicrobial resistance of Enterococcus faecalis isolates of teeth with failure of the endodontic treatment.

METHODS

Twenty root canal samples were collected from teeth with apical periodontitis. E. faecalis was firstly identified based on phenotypic features and then by 16S ribosomal RNA gene sequencing. The antimicrobial susceptibility was determined by the minimum inhibitory concentration (MIC) of amoxicillin, amoxicillin + clavulanate, azithromycin, benzylpenicillin, ciprofloxacin, clindamycin, chloramphenicol, doxycycline, erythromycin, gentamicin, metronidazole, moxifloxacin, rifampicin, tetracycline, and vancomycin using the E test method. Virulence factors (ace, asa, asa373, cylA, efaA, esp, and gelE) were detected by polymerase chain reaction assay.

RESULTS

Amoxicillin + clavulanate was effective against all strains. Intermediate and total resistance was found against the majority of the tested antimicrobials. The susceptibility of some microorganisms to some antimicrobial agents changed according to the evaluation time. MIC50 and MIC90 also varied according to the evaluation time. In relation to the virulence factors of the E faecalis isolates, ace was detected in 100% of the strains, asa (60%), asa373 (15%), efaA (95%), esp (70%), and gelE (75%), whereas cylA was not detected.

CONCLUSIONS

It was concluded that E. faecalis isolates from persistent endodontic infections showed varied degrees of intermediate/total resistance to several antimicrobial agents, with amoxicillin + clavulanate being the most effective agent. Moreover, the strains showed different patterns for virulence gene detection.

Avaliação da suscetibilidade antimicrobiana de bactérias anaeróbias facultativas isoladas de canais radiculares de dentes com insucesso endodôntico frente aos antibióticos de uso sistêmico

<title>Resumo</title><sec><title>Introdução</title><p>Bactérias associadas ao insucesso do tratamento endodôntico são capazes de adquirir e expressar resistência aos agentes antimicrobianos comumente empregados para tratar infecções, o que torna necessário, em determinadas situações, a realização de testes laboratoriais para detectar a resistência ou a suscetibilidade antimicrobiana desses micro-organismos.</p></sec><sec><title>Objetivo</title><p>avaliar a suscetibilidade antimicrobiana das cepas de <italic>Enterococcus faecalis</italic>, <italic>Enterococcus faecium</italic>, <italic>Actinomyces viscosus</italic> e <italic>Staphylococcus aureus</italic> isoladas de canais radiculares de dentes com insucesso endodôntico.</p></sec><sec><title>Material e método</title><p>Cepas clínicas de <italic>Enterococcus faecalis</italic> (n=3), <italic>Enterococcus faecium</italic> (n=3), <italic>Actinomyces viscosus</italic> (n=3) e <italic>Staphylococcus aureus</italic> (n=3), coletadas in vivo de canais radiculares com insucesso endodôntico, foram testadas quanto à suscetibilidade antimicrobiana por meio do método E-test em duplicata, utilizando os antibióticos: Amoxicilina (AC), Rifampicina (RI), Moxifloxacina (MX), Vancomicina (VA), Tetraciclina (TC), Ciprofloxacina (CI), Cloranfenicol (CL), Benzilpenicilina (PG), Amoxicilina + ácido clavulânico (XL), Doxiciclina (DC), Eritromicina (EM) e Azitromicina (AZ).</p></sec><sec><title>Resultado</title><p>Todas as cepas clínicas testadas foram suscetíveis aos antibióticos AC, XL, PG, DC, MX, TC e VA. Todos os isolados das espécies de <italic>S. aureus</italic> foram suscetíveis aos 12 antibióticos testados. As cepas de <italic>E. faecalis</italic>, <italic>E. faecium</italic> e <italic>A. viscosus</italic> mostraram padrão de suscetibilidade intermediário contra EM. Algumas cepas de <italic>E. faecalis</italic> e <italic>E. faecium</italic> foram resistentes a AZ e RI.</p></sec><sec><title>Conclusão</title><p>As cepas clínicas isoladas dos canais radiculares de dentes com insucesso endodôntico mostraram perfis diferentes de suscetibilidade antimicrobiana e nenhum isolado de <italic>E. faecalis</italic> e <italic>E. faecium</italic>apresentou-se suscetível a AZ e EM.</p></sec>

Molecular identification and antibiotic resistant bacteria isolated from primary dentition infections

BACKGROUND

Bacterial resistance to antibiotics is a health problem in many parts of the world. The aim of this study was to identify bacteria from dental infections and determine bacterial resistance to antibiotics used in dental care in the primary dentition.

METHODS

This cross-sectional study comprised 60 children who presented for dental treatment for active dental infections in the primary dentition. Samples from dental infections were collected and bacteria were identified by polymerase chain reaction (PCR) assay. Bacterial resistance to antibiotics was determined by colony forming units on agar plates containing amoxicillin, clindamycin and amoxillicin-clavulanic acid (A-CA) tested at 8 μg/ml or 16 μg/ml.

RESULTS

Clindamycin in both concentrations tested (8 μg/ml and 16 μg/ml) showed the highest bacterial resistance (85.9%), followed by amoxicillin (43.7%) and A-CA (12.0%). All comparisons among the three antibiotics used in the study exhibited statistical significance (p = <0.05) in both concentrations tested (8 μg/ml and 16 μg/ml), and under aerobic and anaerobic conditions. The most prevalent resistant species identified by PCR in primary dentition infections were: Streptococcus oralis and Prevotella intermedia (75.0%); Treponema denticola and Porphyromonas gingivalis (48.3%); Streptococcus mutans (45.0%); Campylobacter rectus; and Streptococcus salivarius (40%).

CONCLUSIONS

This study demonstrated that A-CA exhibited the lowest bacterial resistance for clinical isolates in primary dentition infections.

Patient automedication and professional prescription pattern in an urgency service in Brazil

Several studies have indicated an increased resistance of microorganisms resulting from the widespread use of antimicrobial agents. However, few data are available in the dental literature. The aim of this study was to conduct a survey on the patterns of patient usage of antimicrobial prescriptions agents by dentists. A retrospective cross-sectional study was based on the medical records of 223 patients who sought treatment at the Urgency Service, from a Dental School in the South of Brazil, from March 2009 to March 2011. A specific data sheet was used, with questions regarding: patient age and gender; the main complaint; medications used prior to the service; final diagnosis; proposed dental treatment (including prescription medications); and characteristics of the final prescription. Descriptive and inferential statistics were obtained. There was a high frequency of antibiotic use prior to attendance by young patients (Fisher's exact test, p < 0.05). Toothache of endodontic origin was the most frequent patient complaint (72.6%). Endodontic procedures were the measures most frequently adopted to treat the pain (31.2%). The frequency of patient use of antimicrobials prior to the appointment was 14.3%. According to patient records, 83.9% had no systemic drug prescription after receiving urgency treatment. There were few antimicrobial prescriptions after the urgency treatment. The most frequently prescribed agents were amoxicillin, chlorhexidine, and metronidazole. Local measures were more frequently used than systemic approaches to treat urgencies of dental origin. Antimicrobial agents were not frequently prescribed as adjunctives to local administered at the urgency service.

Beta-lactamic resistance profiles in Porphyromonas, Prevotella, and Parvimonas species isolated from acute endodontic infections

INTRODUCTION

Susceptibility to beta-lactamic agents has changed among anaerobic isolates from acute endodontic infections. The aim of the present study was to determine the prevalence of the cfxA/cfxA2 gene in Prevotella spp., Porphyromonas spp., and Parviomonas micra strains and show its phenotypic expression.

METHODS

Root canal samples from teeth with acute endodontic infections were collected and Porphyromonas, Prevotella, and Parvimonas micra strains were isolated and microbiologically identified with conventional culture techniques. The susceptibility of the isolates was determined by the minimum inhibitory concentration of benzylpenicillin, amoxicillin, and amoxicillin + clavulanate using the E-test method (AB BIODISK, Solna, Sweden). The presence of the cfxA/cfxA2 gene was determined through primer-specific polymerase chain reaction. The nitrocefin test was used to determine the expression of the lactamase enzyme.

RESULTS

Prevotella disiens, Prevotella oralis, Porphyromonas gingivalis, and P. micra strains were susceptible to benzylpenicillin, amoxicillin, and amoxicillin + clavulanate. The cfxA/cfxA2 gene was detected in 2 of 29 isolates (6.9%). Simultaneous detection of the cfxA/cfxA2 gene and lactamase production was observed for 1 Prevotella buccalis strain. The gene was in 1 P. micra strain but was not expressed. Three strains were positive for lactamase production, but the cfxA/cfxA2 gene was not detected through polymerase chain reaction.

CONCLUSIONS

There is a low prevalence of the cfxA/cfxA2 gene and its expression in Porphyromonas spp., Prevotella spp., and P. micra strains isolated from acute endodontic infections. Genetic and phenotypic screening must be performed simultaneously to best describe additional mechanisms involved in lactamic resistance for strict anaerobes.

Detection of antibiotic resistance genes in samples from acute and chronic endodontic infections and after treatment

OBJECTIVE

The purpose of this study was twofold: survey samples from acute and chronic endodontic infections for the presence of genes encoding resistance to beta-lactams, tetracycline and erythromycin, and evaluate the ability of treatment to eliminate these genes from root canals.

DESIGN

DNA extracts from samples of abscess aspirates (n=25) and root canals of teeth with asymptomatic apical periodontitis (n=24) were used as template for direct detection of the genes blaTEM, cfxA, tetM, tetQ, tetW, and ermC using real-time polymerase chain reaction (PCR). Bacterial presence was determined using PCR with universal bacterial primers. Root canals of the asymptomatic cases were also sampled and evaluated after chemomechanical procedures using NiTi instruments with 2.5% NaOCl irrigation.

RESULTS

All abscess and initial root canal samples were positive for bacteria. At least one of the target resistance genes was found in 36% of the abscess samples and 67% of the asymptomatic cases. The most prevalent genes in abscesses were blaTEM (24%) and ermC (24%), while tetM (42%) and tetW (29%) prevailed in asymptomatic cases. The blaTEM gene was significantly associated with acute cases (p=0.02). Conversely, tetM was significantly more prevalent in asymptomatic cases (p=0.008). Treatment eliminated resistance genes from most cases.

CONCLUSIONS

Acute and chronic endodontic infections harboured resistance genes for 3 classes of widely used antibiotics. In most cases, treatment was effective in eliminating these genes, but there were a few cases in which they persisted. The implications of persistence are unknown. Direct detection of resistance genes in abscesses may be a potential method for rapid diagnosis and establishment of proactive antimicrobial therapy.

Microbiological profile and antimicrobial susceptibility pattern of infected root canals associated with periapical abscesses

The aim of this investigation was to identify microorganisms from root canals with periapical abscesses and assess the susceptibility of specific anaerobic bacteria to selected antimicrobials and their β-lactamase production. Sixty root canals were microbiologically investigated. The susceptibility of Anaerococcus prevotii, Fusobacterium necrophorum, F. nucleatum, Parvimonas micra, and Prevotella intermedia/nigrescens to antimicrobials was evaluated with the Etest, whereas β-lactamase production was assessed with nitrocefin. A total of 287 different bacterial strains were recovered, including 201 strict anaerobes. The most frequently strict isolated anaerobes were A. prevotii, P. micra, and F. necrophorum. The selected bacteria were susceptible to all the tested antibiotics, except A. prevotii and Fusobacterium species to azithromycin and erythromycin, as well as A. prevotii and F. necrophorum to metronidazole. None of the microorganisms produced β-lactamase. Gram-positive anaerobic bacteria predominated in the root canals with periapical abscesses. All microorganisms tested were susceptible to benzylpenicillin, amoxicillin, amoxicillin + clavulanate, cefaclor, and clindamycin, producing no β-lactamase.

Osteomyelitis of a long bone due to Fusobacterium nucleatum and Actinomyces meyeri in an immunocompetent adult: a case report and literature review

Background

Fusobacterium species are uncommon causes of osteomyelitis. These organisms are normal flora of the oral cavity. Therefore, they mostly cause osteomyelitis of the head and neck. Hematogenous osteomyelitis at distant sites other than the head and neck has rarely been reported in pediatric or immunocompromised patients. Here, we report the first case of osteomyelitis of a long bone combined with a muscle abscess due to Fusobacterium nucleatum in an otherwise healthy adult.

Case presentation

A 59-year-old Korean man was admitted for pain and swelling of the right lower leg, which had been persistent for two weeks. Magnetic resonance imaging showed osteomyelitis of the right fibula with a surrounding muscle abscess of the right lower leg. Incision and drainage was performed, and repetitive tissue cultures grew F. nucleatum. In this patient, it was presumed that recurrent periodontitis caused hematogenous seeding of F. nucleatum to a distant site leading to osteomyelitis with a muscle abscess. The patient was successfully treated with intravenous ampicillin-sulbactam for three weeks and oral amoxicillin-clavulanate for eight weeks. He also underwent repeated surgical drainage. He has no evidence of recurrence after seven months of follow-up.

Conclusions

Clinicians should be aware that F. nucleatum could be the etiologic agent of hematogenous osteomyelitis of a long bone in an immunocompetent patient.