Actinomyces odontolyticus bacteremia

Actinomyces odontolyticus: A Rare Agent of Exit-Site Infection in Peritoneal Dialysis

Exit-site infections (ESIs) of peritoneal dialysis catheters can cause serious complications if not promptly treated. Uncommon pathogens like Actinomyces odontolyticus are infrequently associated with these infections. We report a 26-year-old woman with end-stage renal disease due to Alport syndrome, presenting with recurrent purulent discharge and erythema at the Tenckhoff catheter exit site. Initial cultures were negative, and empirical treatment with cotrimoxazole was provided with an apparent resolution of the infection. Upon recurrence, A. odontolyticus was identified in an anaerobic culture, showing resistance to multiple antibiotics, including penicillin. Treatment with doxycycline resolved the infection within four weeks without requiring catheter removal. No recurrence was observed after six months. This case highlights the importance of early diagnosis and tailored antibiotic therapy in managing rare infections. It emphasizes the need for collaboration with microbiology labs to ensure proper identification of atypical pathogens. Early intervention and targeted treatment can lead to excellent outcomes, potentially avoiding catheter removal.

Understanding Actinomyces Odontolyticus: A Rare Culprit of Bacteremia

Actinomyces species are gram-positive filamentous non-acid fast anaerobic to microaerophilic bacteria that belong to human oral, gastrointestinal, and urogenital tract flora. Cervicofacial, abdominopelvic, and pulmonary infections are the most common presentations. Hematogenous spread is extremely rare and has been associated with Actinomyces meyeri, Actinomyces israelii, and Actinomyces odontolyticus. It affects individuals with poor oral hygiene, heavy alcohol intake, immunosuppressed, and underlying pulmonary diseases typically between the second and sixth decades of life with the peak incidence being between the fourth and fifth decades. We present a case of A. odontolyticus bacteremia in a patient with uncontrolled diabetes mellitus and chronic sinusitis.

Actinomyces spp. Prosthetic Vascular Graft Infection (PVGI): A Multicenter Case-Series and Narrative Review of the Literature

BACKGROUND

Actinomycosis represents a challenging and under-reported complication of vascular surgery. Optimal management of Actinomyces spp. prosthetic vascular graft infection (PVGI) is highly uncertain because of the paucity of reports on this disease.

METHODS

We conducted a retrospective case-series of Actinomyces-PVGI that occurred in the last five years in two major university hospitals in northern Italy. We searched for previously published cases in the scientific literature.

RESULTS

We report five original cases of Actinomyces spp. prosthetic vascular graft infection following aortic aneurysm repair. Our literature review retrieved eight similar cases. Most patients were immunocompetent males. Most infections were polymicrobial (11/13 cases), with a prevalence of A. odontolyticus involvement (3/13 cases were associated with. Salmonella spp. infection). All cases had a late presentation (≥4 months from graft placement), with 61% associated with an aorto-enteric fistula. All patients received antibiotic therapy, but the duration was highly heterogeneous (from two weeks to life-long antibiotics). The patients without surgical revision experienced septic recurrences (2/13), permanent dysfunction (1/13), or a fatal outcome (2/13), while of the remainder who underwent vascular graft explant, six recovered completely and one developed a periprosthetic abscess. In two cases follow-up was not available.

CONCLUSIONS

This case-series aims to raise the diagnostic suspicion and to describe the current management of Actinomyces-PVGIs. We highlight a high heterogeneity in antibiotic duration, choice of the antibiotic regimen, and surgical management. Higher reporting rate is advisable to produce better evidence and optimize management of this rare complication of vascular surgery.

The diagnosis and management of pulmonary actinomycosis

Pulmonary actinomycosis is a rare infection caused by the bacterial species actinomyces. This paper aims to provide a comprehensive review of pulmonary actinomycosis to improve awareness and knowledge. The literature was analysed using databases including Pubmed, Medline and Embase from 1974 to 2021. After inclusion and exclusion, a total of 142 papers were reviewed. Pulmonary actinomycosis is a rare disease occurring in approximately 1 per 3,000,000 people annually. Historically, pulmonary actinomycosis was a common infection with high mortality; however, the infection has become rarer since the widespread use of penicillins. Actinomycosis is known as "the great masquerade"; however, it can be differentiated from other diseases with acid-fast negative ray-like bacilli and sulphur granules being pathognomonic. Complications of the infection include empyema, endocarditis, pericarditis, pericardial effusion, and sepsis. The mainstay of treatment is prolonged antibiotic therapy, with adjuvant surgery in severe cases. Future research should focus on multiple areas, including the potential risk secondary to immunosuppression from newer immunotherapies, the utility of newer diagnostic techniques and ongoing surveillance post-therapy.

A first case of prosthetic joint infection with Actinomyces radingae

Prosthetic joint infection is a common clinical orthopedic problem but infections caused by Actinomyces species have been rarely reported. An increasing number of reports identifying Actinomyces in cases of prosthetic joint infection suggest it may be an emerging pathogen. We describe here the first known case of a prosthetic joint infection caused by Actinomyces radingae.

Laryngeal and pharyngeal actinomycosis: a systematic review and report of 3 cases

INTRODUCTION

Actinomycosis is a granulomatous infection that rarely involves the larynx or pharynx. Three cases of actinomycosis of the larynx or pharynx from our institution were reviewed and a systematic literature review was performed to better define surgical management, antibiotic therapy, risk factors, and incidence of recurrence or complications.

MATERIALS AND METHODS

PubMed/Medline, Cochrane, Embase, and Google Scholar were searched on November 30, 2021 using the terms "laryngeal actinomycosis", "pharyngeal actinomycosis", "actinomycosis AND larynx", and "actinomycosis AND pharynx." Articles which did not describe appropriate sites or were non-English were excluded. Results were collected for demographic information, site(s) of infection, comorbidities, lesion characteristics and treatments.

RESULTS

Along with three cases reported from our institution, 40 unique cases were reviewed from 37 studies for a total of 43 patients (Table 1). 34 (81.0 %) of the patients were male with the highest incidence of infection in the seventh decade (54.8 %). The most common site for the infection was the larynx (69.0 %) followed by the pharynx (16.7 %). Risk factors included a history of radiation therapy, immunosuppression, inhalational irritant, and diabetes (Table 3). The duration of antibiotic therapy varied greatly, from one month to one year and total follow up ranged from 1 month to 2.5 years (Table 1).

CONCLUSIONS

A comprehensive review of the literature on pharyngolaryngeal actinomycosis shows that this infection has increased prevalence within the head and neck cancer patient population. Similar to cervicofacial actinomycosis, these atypical sites have shown favorable responses to extended antibiotic therapy and generally do not require aggressive surgical management.

A 5-year retrospective study of Actinomyces odontolyticus bacteremia in the state of Qatar, case series

Introduction and importance

Manifestations of infection by A. odontolyticus include thoracic, abdominal, pelvic, and central nervous system disease. In the four decades following its isolation, more than 20 cases of invasive infections were reported in multiple geographic locations including the United States and Europe. As such, A. odontolyticus is an emerging bacterium and related research is encouraged for further characterization of its prevalence and clinical significance. Our case series represents the first case series about A. odontolyticus bacteremia in the state of Qatar.

Methods

We are reporting 15 cases with isolated A. odontolyticus positive blood cultures at Hamad Medical Corporation, State of Qatar from 1/Jan/2016 to 1/Nov/2020. Electronic health records (EHR) of patients who were identified to have positive blood cultures were accessed and the demographics and other clinically related data were collected and mentioned in this manuscript, after obtaining the appropriate approval from the Corporation Medical Research Council (MRC).

Outcomes

We are reporting 15 cases with isolated A. odontolyticus positive blood cultures at Hamad Medical Corporation, State of Qatar from 1/Jan/2016 to 1/Nov/2020.

Conclusion

12 of the 15 reported cases were considered significant and received a complete course of antimicrobial therapy. The patients presented with a wide variety of clinical pictures and were of variable age.

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A. odontolyticus is an emerging bacterium with increasingly reported cases.

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It is an anaerobic, filamentous gram-positive bacterium.

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It is associated with cervical, thoracic, abdominal, and pelvic infections.

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It can affect a wide spectrum of patient population.

Pelvic abscess associated with Actinomyces species ‒ a rare post-cesarean complication

Objectives

Pelvic actinomycotic abscess is uncommon and its presentation as a post-cesarean complication may be confused with hemorrhagic mass. It is still a disease that poses a significant diagnostic challenge. Management and prognosis are not well known for this type of infection.

Case presentation

A 36-year-old woman was admitted to the hospital six days after the cesarean section with abdominal pain and dysuria. The second operation was diagnosed as pelvic abscess, debridement and drainage about 250 mL abscess. Bacterial culture of abscess confirmed as Actinomyces odontolyticus infection. Intravenous penicillin was given immediately, amoxicillin was taken orally for three months after discharge, and no recurrence was found after follow-up for ten months.

Conclusions

Pelvic A. odontolyticus abscess may be confirmed through correct bacterial culture and cured by a short-term course of Amoxicillin. With prompt recognition and treatment, favorable outcomes of pelvic Actinomycotic abscess in the perinatal period could be achieved.

The gut microbiome and microbial metabolites in acute myocardial infarction

Emerging evidence has highlighted the role of the gut microbiome in human health. However, the integrative role of the gut microbiome and microbial metabolites in acute myocardial infarction (AMI) remains unclear. The current study profiled the microbial community through 16S rRNA gene sequencing and shotgun metagenomic sequencing, and measured fecal short-chain fatty acids and circulating choline pathway metabolites among 117 new-onset AMI cases and 78 controls. Significant microbial alternations were observed in AMI patients compared with controls (P = 0.001). The abundances of nine species (e.g., Streptococcus salivarius, Klebsiella pneumoniae) were positively associated, and one species (Roseburia hominis) was inversely associated with AMI status and severity. A gut microbial score at disease onset was associated with the risk of major adverse cardiovascular events in 3.2 years (hazard ratio [95% CI]: 2.01 [1.04-4.24]) in AMI patients. The molar proportions of fecal acetate and butyrate were higher, and the circulating levels of choline and carnitine were lower in AMI patients than in controls. In addition, disease classifiers showed that AMI cases and controls had a more distinct pattern in taxonomical composition than in pathways or metabolites. Our findings suggested that microbial composition and functional potentials were associated with AMI status and severity.

Identification of Dominant Bacteria Isolated From Periodontal Abscesses

Aim:

Various methods investigating the bacterial content causing periodontal abscesses have been applied in studies conducted until today. However, these studies have focused on periodontopathogens. Our study was carried out to research whether different pathogens other than the known periodontopathogens are present in periodontal abscess formation. Therefore, dominant bacterial samples obtained from the periodontal abscess content using the culture-dependent method were identified by 16S rDNA sequencing.

Materials and Methods:

Samples were obtained using a syringe or a periopaper from periodontal abscesses of 20 volunteers who met the research criteria. The three different bacterial colonies that were observed most intensely in each sample were selected and purified, and the isolates obtained were kept until the next characterization. Genomic DNA was isolated from each isolate; 16S rRNA genes were amplified by polymerase chain reaction and identified using DNA sequencing analyses.

Results:

As a result of culture-dependent methods, bacterial species belonging to Streptococcus, Staphylococcus, Neisseria, Actinomyces, Morococcus, Moraxella, and Enterococcus genera were isolated from a total of 60 bacterial isolates, three of which were the most densely growing colonies from each periodontal abscess sample.

Conclusion:

In our study, most of the bacterial species detected were identified for the first time in the bacterial content of periodontal abscesses. In some previously done studies, most of these bacteria species were shown to cause abscesses in different parts of the body. It was concluded that further studies are needed to determine the number and proportion of these bacteria species in total bacterial content to evaluate whether they cause periodontal abscesses.

Case report of an unusual hepatic abscess caused by Actinomyces odontolyticus in a patient with human immunodeficiency virus infection

Background

Actinomyces odontolyticus is not commonly recognized as a causative microbe of liver abscess. The detection and identification of A. odontolyticus in laboratories and its recognition as a pathogen in clinical settings can be challenging. However, in the past decades, knowledge on the clinical relevance of A. odontolyticus is gradually increasing. A. odontolyticus is the dominant oropharyngeal flora observed during infancy [Li et al. in Biomed Res Int 2018:3820215, 2018]. Herein we report a case of severe infection caused by A. odontolyticus in an immunocompromised patient with disruption of the gastrointestinal (GI) mucosa.

Case presentation

We present a unique case of a patient with human immunodeficiency virus infection who was admitted due to liver abscess and was subsequently diagnosed as having coinfection of A. odontolyticus, Streptococcus constellatus, and Candida albicans during the hospital course. The empirical antibiotics metronidazole and ceftriaxone were replaced with the intravenous administration of fluconazole and ampicillin. However, the patient’s condition deteriorated, and he died 3 weeks later.

Conclusion

This report is one of the first to highlight GI tract perforation and its clinical relevance with A. odontolyticus infection. A. odontolyticus infection should be diagnosed early in high-risk patients, and increased attention should be paid to commensal flora infection in immunocompromised individuals.

Metagenomic analysis of a throat swab sample collected in China on a patient infected with Varicella Zoster Virus

Varicella Zoster Virus (VZV) is endemic worldwide, causing varicella in children and zoster upon reactivation in adults. This study concerned a metagenomic analysis of a throat swab sample collected in China, on a young patient suffering from Systemic Lupus Erythematosus (SLE) and diagnosed with varicella. The complete genome sequence of a VZV strain of clade 2 has been generated. Clade 2 strains are the most prevalent in Asian countries. A comparison of 223 VZV genomes identified 77 clade specific markers, 20 of them specific to clade 2. The metagenomic analysis also identified sequences covering most of the genome of the bacteria Schaalia odontolytica also known as Actinomyces odontolyticus. VZV infection and bacterial infection in the context of SLE is further discussed. Even though the patient presented only mild symptoms, this study is a reminder that vaccination against VZV is critical to avoid severe complications like bacterial superinfection or even death in the case of immunodeficiency.

Actinomyces odontolyticus causing meningitis and cervical abscess

Actinomyces spp. are filamentous gram-positive bacilli found in humans as a common flora of the oropharynx, gastrointestinal tract, and urogenital tract. Actinobacteria are normally present in the gums and are a common cause of infection in dental procedures and oral abscesses. To date, no cases of A. odontolyticus causing meningitis and cervical abscess have been reported in online databases. Therefore, we report the first case of A. odontolyticus meningitis and recurrent cervical abscess due to translocation from the oral cavity.

Sepsis due to Actinomyces odontolyticus as a Rare Complication of Neobladder

Sepsis due to Actinomyces odontolyticus (A. odontolyticus) is an extremely rare condition that has been reported only a handful of times. In this report, we showcase an 83-year-old male who had a complication of neobladder procedure and developed sepsis due to A. odontolyticus that was successfully treated with a prolonged course of doxycycline.

Healthcare-Associated Laboratory-Confirmed Bloodstream Infections-Species Diversity and Resistance Mechanisms, a Four-Year Retrospective Laboratory-Based Study in the South of Poland

INTRODUCTION

Regardless of the country, advancements in medical care and infection prevention and control of bloodstream infections (BSIs) are an enormous burden of modern medicine.

OBJECTIVES

The aim of our study was to describe the epidemiology and drug-resistance of laboratory-confirmed BSI (LC-BSIs) among adult patients of 16 hospitals in the south of Poland.

PATIENTS AND METHODS

Data on 4218 LC-BSIs were collected between 2016-2019. The identification of the strains was performed using MALDI-TOF. Resistance mechanisms were investigated according to European Committee on Antimicrobial Susceptibility Testing, EUCAST recommendations.

RESULTS

Blood cultures were collected from 8899 patients, and LC-BSIs were confirmed in 47.4%. The prevalence of Gram-positive bacteria was 70.9%, Gram-negative 27.8% and yeast 1.4%. The most frequently isolated genus was Staphylococcus (50% of all LC-BSIs), with a domination of coagulase-negative staphylococci, while Escherichia coli (13.7%) was the most frequent Gram-negative bacterium. Over 4 years, 108 (2.6%) bacteria were isolated only once, including species from the human microbiota as well as environmental and zoonotic microorganisms. The highest methicillin resistant Staphylococcus aureus (MRSA) prevalence was in intensive care units (ICUs) (55.6%) but S. aureus with resistance to macrolides, lincosamides and streptogramins B (MLSB) in surgery was 66.7%. The highest prevalence of E. faecalis with a high-level aminoglycoside resistance (HLAR) mechanism was in ICUs, (84.6%), while E. faecium-HLAR in surgery was 83.3%. All cocci were fully glycopeptide-sensitive. Carbapenem-resistant Gram-negative bacilli were detected only in non-fermentative bacilli group, with prevalence 70% and more.

CONCLUSIONS

The BSI microbiology in Polish hospitals was similar to those reported in other studies, but the prevalence of MRSA and enterococci-HLAR was higher than expected, as was the prevalence of carbapenem-resistant non-fermentative bacilli. Modern diagnostic techniques, such as MALDI-TOF, guarantee reliable diagnosis.

Characterization of medical relevant anaerobic microorganisms by isothermal microcalorimetry

Detection of anaerobe bacteria by culture methods requires appropriate media, special growth conditions, additional detection techniques and it typically takes several days. Therefore, anaerobes are often missed in patient specimens under routine culture conditions. Microcalorimetry may provide a simple and accurate real-time method for faster and better detection of anaerobes. An isothermal calorimeter which detect minimal changes of temperature over time was used for the calorimetric experiments. In order to find optimal growth conditions, seven reference or clinical strains of medical relevant anaerobe bacteria were tested under different circumstances. First, the strains were tested with different growth media. After determining the optimal medium for each strain, the gas phase was modified by adding 3 mL or 4 mL medium, to evaluate growth under conditions with less oxygen. Cooked Meat Medium was best supporting growth of the tested strains, including Cutibacterium acnes, Fusobacterium nucleatum, Finegoldia magna, Parvimonas micra, Bacteroides fragilis and Actinomyces odontolyticus, followed by thioglycolate. The best medium to detect Clostridioides difficile was H-Medium. All tested strains showed better growth in 4 mL medium than in 3 mL. The detection time ranged between 10 and 72 h. Our results demonstrated that the sensitivity and the detection time of anaerobe bacteria can be improved by isothermal calorimetry with optimization of growth conditions. Therefore, calorimetric detection, a practical, quick and easy-to-do method, has the potential to replace current microbiological methods.

Changes in the gut microbiota during and after commercial helium–oxygen saturation diving in China

Objectives

The influence of commercial helium–oxygen saturation diving on divers’ gut microbiotas was assessed to provide dietary suggestion.

Methods

Faecal samples of 47 divers working offshore were collected before (T1), during (T2) and after (T3) saturation diving. Their living and excursion depths were 55–134 metres underwater with a saturation duration of 12–31 days and PaO2 of 38–65 kPa. The faecal samples were examined through 16S ribosomal DNA amplicon sequencing based on the Illumina sequencing platform to analyse changes in the bacteria composition in the divers’ guts.

Results

Although the α and β diversity of the gut microbiota did not change significantly, we found that living in a hyperbaric environment of helium–oxygen saturation decreased the abundance of the genus Bifidobacterium, an obligate anaerobe, from 2.43%±3.83% at T1 to 0.79%±1.23% at T2 and 0.59%±0.79% at T3. Additionally, the abundance of some short-chain fatty acid (SCFA)-producing bacteria, such as Fusicatenibacter, Faecalibacterium, rectale group and Anaerostipes, showed a decreased trend in the order of before, during and after diving. On the contrary, the abundance of species, such as Lactococcus garvieae, Actinomyces odontolyticus, Peptoclostridium difficile, Butyricimonas virosa, Streptococcus mutans, Porphyromonas asaccharolytica and A. graevenitzii, showed an increasing trend, but most of them were pathogens.

Conclusions

Occupational exposure to high pressure in a helium–oxygen saturation environment decreased the abundance of Bifidobacterium and some SCFA-producing bacteria, and increased the risk of pathogenic bacterial infection. Supplementation of the diver diet with probiotics or prebiotics during saturation diving might prevent these undesirable changes.

Actinomyces odontolyticus infection 3 months post-robotic-assisted laparoscopic prostatectomy

Actinomyces odontolyticus infection is a rare bacterial infection with only 46 cases reported from its discovery in 1958. This case highlights an immunocompetent patient who presented with an infected lymphocele and bacteraemia following a robotic-assisted laparoscopic prostatectomy and extended pelvic lymph node dissection 3 months previously. He was treated for a fever of unclear origin initially using amoxicillin, gentamicin and metronidazole. Subsequently, he was found to have an infected lymphocele, which required surgical drainage. He was discharged 19 days after admission with three times daily oral amoxicillin which is to be continued for 6-12 months. This case highlights the need for effective communication between the laboratory and medical teams, and the importance of prompt source control.

Abdominal and pelvic actinomycosis due to longstanding intrauterine device: a slow and devastating infection

Actinomycosis is a chronic or subacute bacterial infection characterized by large abscess formation, caused mainly by the gram-positive non-acid-fast, anaerobic, or microaerophilic/capnophilic, obligate parasites bacteria from the Actinomyces genus. Although pelvic inflammatory disease is an entity associated with the longstanding use of intrauterine devices (IUDs), actinomycosis is not one of the most frequent infections associated with IUDs. We present the case of a 43-year-old female patient who was referred to the emergency facility because of a 20-day history of abdominal pain with signs of peritoneal irritation. Imaging exams revealed collections confined to the pelvis, plus the presence of an IUD and evidence of sepsis, which was consistent with diffuse peritonitis. An exploratory laparotomy was undertaken, and a ruptured left tubal abscess was found along with peritonitis, and a huge amount of purulent secretion in the pelvis and abdominal cavity. Extensive lavage of the cavities with saline, a left salpingo-oophorectomy, and drainage of the cavities were performed. The histopathological examination of the surgical specimen revealed an acute salpingitis with abscesses containing sulfur granules. Therefore, the diagnosis of abdominal and pelvic actinomycosis was made. The postoperative outcome was troublesome and complicated with a colocutaneous fistula, which drained through the surgical wound. A second surgical approach was needed, requiring another extensive lavage and drainage of the recto-uterine pouch, plus the performance of a colostomy. Broad-spectrum antibiotics added to ampicillin were the first antimicrobial regimen followed by 4 weeks of amoxicillin during the outpatient follow-up. The patient satisfactorily recovered and is already scheduled for the intestinal transit reconstitution.

Cardiac Tamponade Due to Actinomyces odontolyticus Originating From a Dentigerous Cyst

This report describes a rare case of pericardial effusion owing to Actinomyces odontolyticus in a 52-year-old woman that originated from a dentigerous cyst, which developed on the distal aspect of a lower left third molar. The cyst had remained asymptomatic for a long period, with no specific functional complications. This is the first case report of a patient with acute pericarditis in which the same strain of A odontolyticus was detected in an asymptomatic dentigerous cyst and in the pericardial fluid.

Partial denture metal framework may harbor potentially pathogenic bacteria

PURPOSE

The aim of this study was to characterize and compare bacterial diversity on the removable partial denture (RPD) framework over time.

MATERIALS AND METHODS

This descriptive pilot study included five women who were rehabilitated with free-end mandibular RPD. The biofilm on T-bar clasps were collected 1 week (t₁) and 4 months (t₂) after the RPD was inserted (t₀). Bacterial 16S rDNA was extracted and PCR amplified. Amplicons were cloned; clones were submitted to cycle sequencing, and sequences were compared with GenBank (98% similarity).

RESULTS

A total of 180 sequences with more than 499 bp were obtained. Two phylogenetic trees with 84 (t₁) and 96 (t₂) clones represented the bacteria biofilm at the RPD. About 93% of the obtained phylotypes fell into 25 known species for t₁ and 17 for t₂, which were grouped in 5 phyla: Firmicutes (t₁=82%; t₂=60%), Actinobacteria (t₁=5%; t₂=10%), Bacteroidetes (t₁=2%; t₂=6%), Proteobacteria (t₁=10%; t₂=15%) and Fusobacteria (t₁=1%; t₂=8%). The libraries also include 3 novel phylotypes for t₁ and 11 for t₂. Library t₂ differs from t₁ (P=.004); t₁ is a subset of the t₂ (P=.052). Periodontal pathogens, such as F. nucleatum, were more prevalent in t₂.

CONCLUSION

The biofilm composition of the RPD metal clasps changed along time after RPD wearing. The RPD framework may act as a reservoir for potentially pathogenic bacteria and the RPD wearers may benefit from regular follow-up visits and strategies on prosthesis-related oral health instructions.

Impact of Denture Cleaning Method and Overnight Storage Condition on Denture Biofilm Mass and Composition: A Cross-Over Randomized Clinical Trial

BACKGROUND

Appropriate oral hygiene is required to maintain oral health in denture wearers. This study aims to compare the role of denture cleaning methods in combination with overnight storage conditions on biofilm mass and composition on acrylic removable dentures.

METHODS

In a cross-over randomized controlled trial in 13 older people, 4 conditions with 2 different mechanical cleaning methods and 2 overnight storage conditions were considered: (i) brushing and immersion in water without a cleansing tablet, (ii) brushing and immersion in water with a cleansing tablet, (iii) ultrasonic cleaning and immersion in water without a cleansing tablet, and (iv) ultrasonic cleaning and immersion in water with a cleansing tablet. Each test condition was performed for 5 consecutive days, preceded by a 2-days wash-out period. Biofilm samples were taken at baseline (control) and at the end of each test period from a standardized region. Total and individual levels of selected oral bacteria (n = 20), and of Candida albicans were identified using the Polymerase Chain Reaction (PCR) technique. Denture biofilm coverage was scored using an analogue denture plaque score. Paired t-tests and Wilcoxon-signed rank tests were used to compare the test conditions. The level of significance was set at α< 5%.

RESULTS

Overnight denture storage in water with a cleansing tablet significantly reduced the total bacterial count (p<0.01). The difference in total bacterial level between the two mechanical cleaning methods was not statistically significant. No significant effect was observed on the amount of Candida albicans nor on the analogue plaque scores.

CONCLUSIONS

The use of cleansing tablets during overnight denture storage in addition to mechanical denture cleaning did not affect Candida albicans count, but reduced the total bacterial count on acrylic removable dentures compared to overnight storage in water. This effect was more pronounced when combined with ultrasonic cleaning compared to brushing.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02454413.

Metal Ion-Mediated Nucleobase Recognition by the ZTP Riboswitch

The ZTP riboswitch is a widespread family of regulatory RNAs that upregulate de novo purine synthesis in response to increased intracellular levels of ZTP or ZMP. As an important intermediate in purine biosynthesis, ZMP also serves as a proxy for the concentration of N10-formyl-tetrahydrofolate, a key component of one-carbon metabolism. Here, we report the structure of the ZTP riboswitch bound to ZMP at a resolution of 1.80 Å. The RNA contains two subdomains brought together through a long-range pseudoknot further stabilized through helix-helix packing. ZMP is bound at the subdomain interface of the RNA through a set of interactions with the base, ribose sugar, and phosphate moieties of the ligand. Unique to nucleobase recognition by RNAs, the Z base is inner-sphere coordinated to a magnesium cation bound by two backbone phosphates. This interaction, along with steric hindrance by the backbone, imparts specificity over chemically similar compounds such as ATP/AMP.

Actinomyces and related organisms in human infections

Actinomyces israelii has long been recognized as a causative agent of actinomycosis. During the past 3 decades, a large number of novel Actinomyces species have been described. Their detection and identification in clinical microbiology laboratories and recognition as pathogens in clinical settings can be challenging. With the introduction of advanced molecular methods, knowledge about their clinical relevance is gradually increasing, and the spectrum of diseases associated with Actinomyces and Actinomyces-like organisms is widening accordingly; for example, Actinomyces meyeri, Actinomyces neuii, and Actinomyces turicensis as well as Actinotignum (formerly Actinobaculum) schaalii are emerging as important causes of specific infections at various body sites. In the present review, we have gathered this information to provide a comprehensive and microbiologically consistent overview of the significance of Actinomyces and some closely related taxa in human infections.

The rising tide of bloodstream infections with Actinomyces species: bimicrobial infection with Actinomyces odontolyticus and Escherichia coli in an intravenous drug user

Clinicians of all specialties need to be aware of a recent, nationwide increase in the number of Actinomyces bloodstream infections. We report a case of bimicrobial bloodstream infection with Actinomyces odontolyticus and Escherichia coli in an intravenous drug user. A 36-year-old, male intravenous drug user was admitted with acute-onset pleuritic chest pain, back pain, pyrexia, tachycardia, tachypnoea and hypotension. Chest CT showed multiple, bilateral, cavitating lung lesions, most likely the result of septic emboli originating from an infected deep venous thrombosis (DVT). Blood cultures led to a mixed growth of A. odontolyticus, identified by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF), and E. coli. The rising tide of bloodstream infections with Actinomyces species is likely to continue with the increasing availability of sophisticated molecular identification techniques, including MALDI-TOF. In this case, the results of antimicrobial susceptibility tests were particularly important because the E. coli was susceptible to ciprofloxacin, whereas the A. odontolyticus was resistant.

Actinomycosis: etiology, clinical features, diagnosis, treatment, and management

Actinomycosis is a rare chronic disease caused by Actinomyces spp., anaerobic Gram-positive bacteria that normally colonize the human mouth and digestive and genital tracts. Physicians must be aware of typical clinical presentations (such as cervicofacial actinomycosis following dental focus of infection, pelvic actinomycosis in women with an intrauterine device, and pulmonary actinomycosis in smokers with poor dental hygiene), but also that actinomycosis may mimic the malignancy process in various anatomical sites. Bacterial cultures and pathology are the cornerstone of diagnosis, but particular conditions are required in order to get the correct diagnosis. Prolonged bacterial cultures in anaerobic conditions are necessary to identify the bacterium and typical microscopic findings include necrosis with yellowish sulfur granules and filamentous Gram-positive fungal-like pathogens. Patients with actinomycosis require prolonged (6- to 12-month) high doses (to facilitate the drug penetration in abscess and in infected tissues) of penicillin G or amoxicillin, but the duration of antimicrobial therapy could probably be shortened to 3 months in patients in whom optimal surgical resection of infected tissues has been performed. Preventive measures, such as reduction of alcohol abuse and improvement of dental hygiene, may limit occurrence of pulmonary, cervicofacial, and central nervous system actinomycosis. In women, intrauterine devices must be changed every 5 years in order to limit the occurrence of pelvic actinomycosis.

Amplicon pyrosequencing and ion torrent sequencing of wild duck eubacterial microbiome from fecal samples reveals numerous species linked to human and animal diseases

Our investigation into the composition of the wild duck,Aythya americana, eubacterial microbiome from a fecal sample using amplicon pyrosequencing revealed that the representative bacterial species were quite distinct from a pond water sample, and we were able to classify the major operational taxonomic units withFusobacterium mortiferum,Streptobacillus moniliformis,Lactobacillus intermedius,Actinomyces suimastitidis,Campylobacter Canadensis,Enterococcus cecorum,Lactobacillus aviarus,Actimomyces spp.,Pseudobutyrivibrio spp.and Helicobacter brantaerepresenting the majority of the eubacterial fecal microbiome.  Bacterial species present in the analysis revealed numerous organisms linked to human and animal diseases including septicemia, rat bite fever, pig mastitis, endocarditis, malar masses, genital infections, skin lesions, peritonitis, wound infections, septic arthritis, urocystitis, gastroenteritis and drinking water diseases.  In addition, to being known carriers of viral pathogens wild ducks should also be recognized as a potential source of a range of bacterial diseases.

The cultivable human oral gluten-degrading microbiome and its potential implications in coeliac disease and gluten sensitivity

Coeliac disease is characterized by intestinal inflammation caused by gluten, proteins which are widely contained in the Western diet. Mammalian digestive enzymes are only partly capable of cleaving gluten, and fragments remain that induce toxic responses in patients with coeliac disease. We found that the oral microbiome is a novel and rich source of gluten-degrading organisms. Here we report on the isolation and characterization of the cultivable resident oral microbes that are capable of cleaving gluten, with special emphasis on the immunogenic domains. Bacteria were obtained by a selective culturing approach and enzyme activities were characterized by: (i) hydrolysis of paranitroanilide-derivatized gliadin-derived tripeptide substrates; (ii) gliadin degradation in-gel (gliadin zymography); (iii) gliadin degradation in solution; (iv) proteolysis of the highly immunogenic α-gliadin-derived 33-mer peptide. For selected strains pH activity profiles were determined. The culturing strategy yielded 87 aerobic and 63 anaerobic strains. Species with activity in at least two of the four assays were typed as: Rothia mucilaginosa HOT-681, Rothia aeria HOT-188, Actinomyces odontolyticus HOT-701, Streptococcus mitis HOT-677, Streptococcus sp. HOT-071, Neisseria mucosa HOT-682 and Capnocytophaga sputigena HOT-775, with Rothia species being active in all four assays. Cleavage specificities and substrate preferences differed among the strains identified. The approximate molecular weights of the enzymes were ~75 kD (Rothia spp.), ~60 kD (A. odontolyticus) and ~150 kD (Streptococcus spp.). In conclusion, this study identified new gluten-degrading microorganisms in the upper gastrointestinal tract. A cocktail of the most active oral bacteria, or their isolated enzymes, may offer promising new treatment modalities for coeliac disease.

The cultivable human oral gluten-degrading microbiome and its potential implications in coeliac disease and gluten sensitivity

Coeliac disease is characterized by intestinal inflammation caused by gluten, proteins which are widely contained in the Western diet. Mammalian digestive enzymes are only partly capable of cleaving gluten, and fragments remain that induce toxic responses in patients with coeliac disease. We found that the oral microbiome is a novel and rich source of gluten-degrading organisms. Here we report on the isolation and characterization of the cultivable resident oral microbes that are capable of cleaving gluten, with special emphasis on the immunogenic domains. Bacteria were obtained by a selective culturing approach and enzyme activities were characterized by: (i) hydrolysis of paranitroanilide-derivatized gliadin-derived tripeptide substrates; (ii) gliadin degradation in-gel (gliadin zymography); (iii) gliadin degradation in solution; (iv) proteolysis of the highly immunogenic α-gliadin-derived 33-mer peptide. For selected strains pH activity profiles were determined. The culturing strategy yielded 87 aerobic and 63 anaerobic strains. Species with activity in at least two of the four assays were typed as: Rothia mucilaginosa HOT-681, Rothia aeria HOT-188, Actinomyces odontolyticus HOT-701, Streptococcus mitis HOT-677, Streptococcus sp. HOT-071, Neisseria mucosa HOT-682 and Capnocytophaga sputigena HOT-775, with Rothia species being active in all four assays. Cleavage specificities and substrate preferences differed among the strains identified. The approximate molecular weights of the enzymes were ~75 kD (Rothia spp.), ~60 kD (A. odontolyticus) and ~150 kD (Streptococcus spp.). In conclusion, this study identified new gluten-degrading microorganisms in the upper gastrointestinal tract. A cocktail of the most active oral bacteria, or their isolated enzymes, may offer promising new treatment modalities for coeliac disease.

Integrating next-generation sequencing and traditional tongue diagnosis to determine tongue coating microbiome

Tongue diagnosis is a unique method in traditional Chinese medicine (TCM). This is the first investigation on the association between traditional tongue diagnosis and the tongue coating microbiome using next-generation sequencing. The study included 19 gastritis patients with a typical white-greasy or yellow-dense tongue coating corresponding to TCM Cold or Hot Syndrome respectively, as well as eight healthy volunteers. An Illumina paired-end, double-barcode 16S rRNA sequencing protocol was designed to profile the tongue-coating microbiome, from which approximately 3.7 million V6 tags for each sample were obtained. We identified 123 and 258 species-level OTUs that were enriched in patients with Cold/Hot Syndromes, respectively, representing "Cold Microbiota" and "Hot Microbiota". We further constructed the tongue microbiota-imbalanced networks associated with Cold/Hot Syndromes. The results reveal an important connection between the tongue-coating microbiome and traditional tongue diagnosis, and illustrate the potential of the tongue-coating microbiome as a novel holistic biomarker for characterizing patient subtypes.

Laser raman spectroscopy as a potential chair-side microbiological diagnostic device

INTRODUCTION

Culture-dependent and -independent techniques are time-consuming processes requiring highly trained personnel to identify microorganisms contained within a sample. Rapid chair-side identification of microorganisms could reduce the lag time between patient presentation and ideal treatment. As a first step toward this goal, this study aims to determine if laser Raman spectroscopy (LRS) can discern uniqueness among 10 different species of bacteria contained within a medium in unprocessed and processed samples.

METHODS

Ten bacterial species were individually grown on blood agar plates for 3 days. Checkerboard DNA-DNA hybridization was used for species verification. For the unprocessed samples, a 1.0-cm diameter agar sample, with undisturbed bacterial growth, was transferred for each species to a barium fluoride crystal (BaF(2)) slide and laser scanned for a total of 15 seconds per sample. For the processed samples, bacterial cells were harvested, washed, and resuspended in phosphate-buffered saline buffer at 10(9) cells/mL concentration. Each suspension was laser scanned for 15 seconds on a BaF(2) slide. Select regions of Raman spectra for each species/agar and species/suspension combination were processed using a two-sided t test.

RESULTS

For the 10 bacterial species, 45 bacteria pair combinations were tested for each group. In both groups, LRS was capable of statistically distinguishing among a majority of bacterial pairings based on RS signature differences of means.

CONCLUSIONS

Results show each bacterial species generated restricted ranges of unique spectral signatures that were not masked by their containing medium. Chair-side LRS is a promising technique that differentiates among oral bacterial species with a high degree of specificity.

Actinomyces graevenitzii bacteremia in a patient with alcoholic liver cirrhosis

We report the first case of Actinomyces graevenitzii septicemia in a patient with alcoholic liver cirrhosis. It was identified as A. graevenitzii by morphologic and 16S rRNA sequencing. Even though A. graevenitzii is rarely associated with human infections, it should be considered as a potential causative agent of bacteremia.

Actinomyces neuii: review of an unusual infectious agent

Actinomyces neuii, a species first described in 1994, has proven to be an exception in this genus on account of its aerobic growth, microscopic morphology (no branching), and the types and location of infections. Abscesses and infected atheromas are the most frequent types of infections, followed by infected skin structures, endophthalmitis, and bacteremias, including endocarditis. They are most likely of endogenous origin. To date, approximately 100 cases have been recorded in the literature. Intra-abdominal and intrathoracic infections, however, have not yet been described, and cases of classical actinomycosis seem to be extremely rare. Prognosis has generally been good with antibiotic and/or surgical treatment. Susceptibility to antibiotics has paralleled that of other Actinomyces spp.

Liver abscess due to Actinomyces odontolyticus in an immunocompetent patient

Liver abscess caused by Actinomyces odontolyticus is rarely reported. We report an immunocompetent patient who developed A. odontolyticus liver abscess, and was successfully treated with antibiotics for 6 weeks and abscess drainage. The isolate could not be identified accurately by one commercial biochemical method and was documented to species level by partial sequencing analysis of 16S rRNA genes.

Safety and Efficacy Review of Doxycycline

Doxycycline is a member of the tetracycline class of antibiotics and has been used clinically for more than 40 years. It is a well-tolerated drug that is bacteriostatic and acts via the inhibition of bacterial ribosomes. It is generally given at a dose of 100-mg daily or twice daily. It is well absorbed and has generally good tissue penetration. The serum half-life is 18-22 hours and dosage does not need to be adjusted in the presence of renal or hepatic impairment. Major side effects are gastro-intestinal and dermatological and it is generally contra-indicated in pregnancy or childhood because of concerns about discolouration of developing teeth and potential effects on growing bones. Drug interactions are not common although can occur with the concomitant use of methotrexate and the oral contraceptive pill, and its absorption can be reduced by the co-administration with some antacids and iron preparations. It has activity against many organisms, including Gram-positives, Gram-negatives and atypical bacteria. In addition, it appears to have some potentially clinically useful anti-inflammatory properties.