Clinical Characteristics of Actinomyces viscosus Bacteremia

Bacteria of healthy periodontal tissues as candidates of probiotics: a systematic review

OBJECTIVES

The use of probiotics could promote the balance of the subgingival microbiota to contribute to periodontal health. This study aimed to identify the potential of bacteria commonly associated with healthy periodontal tissues as probiotic candidates.

MATERIAL AND METHODS

A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines using the PubMed, Scopus, Science Direct, ProQuest, and Ovid databases as well as the combination of Medical Subject Headings (MeSH) and non-MeSH terms. Based on the selection criteria, original studies published in English and identifying the microorganisms present in the periodontium of healthy individuals and patients with periodontitis using the high-throughput 16S ribosomal gene sequencing technique were included.

RESULTS

Out of 659 articles, 12 met the criteria for this review. These articles were published from 2012 to 2020 and mainly originated from the United States, China, and Spain. Most of these studies reported adequate criteria for selecting participants, using standardized clinical criteria, and compliance with quality based on the tools used. In periodontal healthy tissue were identified species like Actinomyces viscosus, Actinomyces naeslundii, Haemophilus parainfluenzae, Rothia dentocariosa, Streptococcus sanguinis, Streptococcus mitis, Streptococcus oralis, Streptococcus gordonii, Streptococcus intermedius, and Prevotella nigrescens which have recognized strains with a capacity to inhibit periodontopathogens.

CONCLUSIONS

S. sanguinis, S. oralis, S. mitis, and S. gordonii are among the bacterial species proposed as potential probiotics because some strains can inhibit periodontopathogens and have been reported as safe for humans.

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.

Microbiological Analysis and Mortality Risk Factors in Patients with Polymicrobial Bloodstream Infections

Purpose

To study the etiological characteristics and risk factors affecting the prognosis of patients with polymicrobial bloodstream infections.

Patients and Methods

Overall, 141 patients with polymicrobial bloodstream infections in Henan Provincial People's Hospital during 2021 were included. Laboratory test indexes, department of admission, sex, age, intensive care unit (ICU) admission, surgical history, and central venous catheter placement were collected. Patients were divided into surviving and deceased groups based on outcomes at discharge. Mortality risk factors were identified by univariate and multivariable analyses.

Results

Seventy-two of 141 patients survived. Patients were mainly from the ICU and the Departments of Hepatobiliary Surgery and Hematology. Overall, 312 microbial strains were detected: 119 gram-positive, 152 gram-negative, and 13 anaerobic bacteria and 28 fungi. Among the gram-positive bacteria, coagulase-negative staphylococci were most frequent (44/119, 37%), followed by enterococci (35/119, 29.4%). Among coagulase-negative staphylococci, methicillin-resistant coagulase-negative staphylococci incidence was 75% (33/44). Among gram-negative bacteria, Klebsiella pneumoniae was most common (45/152, 29.6%), followed by Escherichia coli (25/152, 16.4%) and Pseudomonas aeruginosa (13/152, 8.6%). Among K. pneumoniae, the incidence of carbapenem-resistant (CR) K. pneumoniae was 45.7% (21/45). On univariate analysis, mortality risk factors included increased white blood cells and C-reactive protein, decreased total protein and albumin, CR strains, ICU admission, central venous catheter, multiple organ failure, sepsis, shock, pulmonary diseases, respiratory failure, central nervous system diseases, cardiovascular diseases, hypoproteinemia, and electrolyte disturbances (P < 0.05). Multivariable analysis showed that ICU admission, shock, electrolyte disorders, and central nervous system diseases were independent mortality risk factors. The survival curve shows that the survival rate of patients with polymicrobial CR bloodstream infections was lower than that of patients with polymicrobial non-CR bloodstream infections (P=0.029).

Conclusion

Patients with polymicrobial bloodstream infections are typically critically ill and harbor multidrug-resistant bacteria. Thus, to minimize mortality rate in critically ill patients, changes in infectious flora should be monitored, antibiotics selected reasonably, and invasive procedures reduced.

Gut microbiota diversity of hospitalized older adult patients with and without antibiotic-associated diarrhea

BACKGROUND

The incidence of antibiotic-related diarrhea (AAD) is high in older adults.

AIM

To examine the gut microbiota changes in older adults who received antibiotics to identify the microbial signatures associated with antibiotic use and AAD.

METHODS

A nested prospective observational cohort study was conducted between December 2019 and June 2021 in patients ≥ 65 years old at Huashan Hospital affiliated with Fudan University. The patients were grouped as antibiotic-treated (HA group) and no antibiotics (HC group); the HA group was subdivided as with vs. without AAD. Fecal samples were collected at admission (i.e., before eventual antibiotics) and after 7 days.

RESULT

Thirty-eight and 19 participants were included in the HA and HC groups. There were significant differences in gut microbiota between the HA after antibiotics vs. HC groups, with a higher Firmicutes/Bacteroidetes ratio. Before antibiotics in the HA group, the relative abundances of Akkermansia and Alistipes were lower in the AAD subgroup than the no-AAD subgroup, while the relative abundance of Actinomyces was higher. After antibiotics in the HA group, specific bacterial species were decreased in the AAD subgroup compared with the no-AAD subgroup. Among HA participants without probiotics, the abundance of Akkermansia in the patients without AAD was higher than in the patients with AAD at baseline (P = 0.007).

CONCLUSION

Patients with or without AAD have different gut microbiota compositions before antibiotics. Antibiotics can lead to dysbiosis, with a decrease in beneficial bacteria and an increase in Enterococcus.

Normal bacterial flora of the oral cavity in healthy pet rabbits (Oryctolagus cuniculus)

BACKGROUND

Rabbits often suffer from dental disease, including dental abscesses and periodontal/apical infections. With odontogenic infection and abscessation, a bacterial aetiology can be proven by bacterial culture and identification. Although studies exist on the bacterial flora of dental abscesses, the information available to date on the bacterial flora of the oral cavity in healthy rabbits is limited.

OBJECTIVES

This study aims to evaluate the cultivable bacterial flora in the oral cavity of healthy, young, pet rabbits and to compare this flora with the pathologic flora of odontogenic abscesses described in the literature.

METHODS

Samples were collected from the oral cavity of 33 healthy, young pet rabbits undergoing routine procedures. Oral cavity culture specimens were collected by rolling a sterile flocked paediatric swab in the mouth. Identification was first attempted by morphological assessment, Gram staining and mass spectrometry (MALDI-TOF). Colonies that could not be identified by mass spectrometry were identified by amplification and molecular sequencing of a part of the 16s rRNA gene.

RESULTS

Bacteria were recovered from 100% of oral swabs; 220 isolates of 35 different genera of bacteria were cultured. The most frequently isolated bacteria were Streptococcus sp. (19.8%), Rothia sp. (17.9%), Enterobacter sp. (7%), Staphylococcus sp. (6.6%) and Actinomyces sp. (5.7%). Four phyla are represented: Proteobacteria (38.3%), Firmicutes (30.5%), Actinobacteria (26.9%) and Bacteroidota (4.3%).

CONCLUSIONS

A wide range of commensal bacteria are present in the mouths of rabbits. Bacterial cultures taken from cases of dental abscesses often reveal bacteria. Streptococcus sp., Staphylococcus sp. and Actinomyces sp. are frequently found in cultures from dental abscesses, in contrast to Rothia and Enterobacter species. Our findings enhance the knowledge of rabbit microbial communities throughout oral cavity.