Pathogenic mechanisms of cariogenic Propionibacterium acidifaciens.

OBJECTIVE: Dental caries is one of the most common infectious diseases in humans. Older adults retain more teeth than did earlier generations and thus are at high risk of root caries. The root surface is covered by cementum, which facilitates the spread of caries lesions into dentinal tissues. Propionibacterium acidifaciens has been detected in dentinal caries lesions; however, the pathogenetic mechanisms are not known. The purpose of this study was to investigate the pathogenic mechanisms of cariogenic P. acidifaciens. METHODS: Saliva-induced aggregation of P. acidifaciens cells and adherence of the organism to saliva-coated hydroxyapatite were examined. Coaggregation of P. acidifaciens with other bacterial cells and binding of the organism to collagen were examined. Effect of Streptococcus mutans on the biofilm formation by P. acidifaciens was also examined. In addition, the effects of acids on the growth of P. acidifaciens were evaluated. RESULTS: P. acidifaciens exhibited strong binding to collagen but weak or moderate interaction with salivary proteins. P. acidifaciens showed weak coaggregation with streptococcal strains and Fusobacerium nucleatum. Biofilm formation by P. acidifaciens was inhibited by S. mutans. Moreover, P. acidifaciens tolerated to self-produced acids up to threshold concentrations. CONCLUSIONS: The results suggest that P. acidifaciens can bind to and survive inside dentinal tissue, and its acid production at low pH condition is involved in the development of dentinal caries.

The serum level of C-reactive protein alone cannot be used for the diagnosis of prosthetic joint infections, especially in those caused by organisms of low virulence.

AIMS: The aim of this study was to determine the prevalence and characteristics of C-reactive protein (CRP)-negative prosthetic joint infection (PJI) and evaluate the influence of the type of infecting organism on the CRP level. PATIENTS AND METHODS: A retrospective analysis of all PJIs affecting the hip or knee that were diagnosed in our institution between March 2013 and December 2016 was performed. A total of 215 patients were included. Their mean age was 71 years (sd 11) and there were 118 women (55%). The median serum CRP levels were calculated for various species of organism and for patients with acute postoperative, acute haematogenous, and chronic infections. These were compared using the Kruskal-Wallis test, adjusting for multiple comparisons with Dunn's test. The correlation between the number of positive cultures and serum CRP levels was estimated using Spearman correlation coefficient. RESULTS: Preoperative CRP levels were normal (< 10 mg/l) in 77 patients (35.8%) with positive cultures. Low-virulent organisms were isolated in 66 PJIs (85.7%) with normal CRP levels. When grouping organisms by species, patients with an infection caused by Propionibacterium spp., coagulase-negative staphylococci (CNS), and Enterococcus faecalis had significantly lower median serum CRP levels (5.4 mg/l, 12.2 mg/l, and 23.7 mg/l, respectively), compared with those with infections caused by Staphylococcus aureus and Streptococcus spp. (194 mg/l and 89.3 mg/l, respectively; p < 0.001). Those with a chronic PJI had statistically lower median serum CRP levels (10.6 mg/l) than those with acute postoperative and acute haematogenous infections (83.7 mg/l and 149.4 mg/l, respectively; p < 0.001). There was a significant correlation between the number of positive cultures and serum CRP levels (Spearman correlation coefficient, 0.456; p < 0.001). CONCLUSION: The CRP level alone is not accurate as a screening tool for PJI and may yield high false-negative rates, especially if the causative organism has low virulence. Aspiration of the joint should be used for the diagnosis of PJI in patients with a chronic painful arthroplasty, irrespective of CRP level. Cite this article: Bone Joint J 2018;100-B:1482-86.

Compatibility and safety of five lectin-binding putative probiotic strains for the development of a multi-strain protective culture for poultry.

The ban on the use of antibiotics as feed additives for animal growth promotion in the European Union and United States and the expectation of this trend to further expand to other countries in the short term have prompted a surge in probiotic research. Multi-species probiotics including safe and compatible strains with the ability to bind different nutritional lectins with detrimental effects on poultry nutrition could replace antibiotics as feed additives. Lactobacillus salivarius LET201, Lactobacillus reuteri LET210, Enterococcus faecium LET301, Propionibacterium acidipropionici LET103 and Bifidobacterium infantis CRL1395 have proved to be compatible as evaluated through three different approaches: the production and excretion of antimicrobial compounds, growth inhibition by competition for essential nutrients and physical contact, and a combination of both. The safety of P. acidipropionici LET103 was confirmed, since no expression of virulence factors or antibiotic resistance was detected. The innocuity of E. faecium LET301 should be further evaluated, since the presence of genes coding for certain virulence factors (gelE, efaAfm and efaAfs) was observed, albeit no expression of gelE was previously detected for this strain and there are no reports of involvement of efaAfm in animal pathogenicity. Finally, a combination of the five strains effectively protected intestinal epithelial cells of broilers from the cytotoxicity of mixtures of soybean agglutinin, wheat germ agglutinin and concanavalin A. To our knowledge, this is the first time that a combination of strains is evaluated for their protection against lectins that might be simultaneously present in poultry feeds.

Propionibacterium avidum: A Virulent Pathogen Causing Hip Periprosthetic Joint Infection.

Background: Propionibacteria are important members of the human skin microbiota, but are also opportunistic pathogens associated with periprosthetic joint infection (PJI). While the role of Propionibacterium acnes in PJI has been widely described, insight into the capacity of Propionibacterium avidum to cause PJI is limited. Methods: An unusual cluster of 4 hip PJIs caused by P. avidum in one orthopedic center in 2015 prompted us to retrospectively identify and analyze clinical data related to previous P. avidum PJI cases (1997-2015). We also characterized the hemolytic and biofilm-producing capacity of our 4 clinical P. avidum strains isolated in 2015, and investigated their phylogenetic relationships by whole-genome sequencing. Results: We retrospectively identified 13 P. avidum PJIs, with the majority being hip-related infections (n = 11). Preoperative synovial fluid cultures were P. avidum positive in 63.6% of cases. Six of 12 patients (50%) with available case histories were treated with an exchange of the prosthesis. In all but 1 of the 6 patients treated with debridement-retention of the prosthesis, treatment failed, thus requiring a 2-stage revision. The isolated P. avidum strains showed a more pronounced hemolytic activity, but a similar biofilm-forming ability when compared to P. acnes. Whole-genome sequencing identified 2 phylogenetic clusters highly related to P. avidum PJI strains isolated in Sweden. Conclusions: We describe the largest series of P. avidum PJI predominantly located in the hip. Phylogenetic similarity of our P. avidum strains to PJI strains isolated elsewhere suggests that these invasive lineages may be common.

Aspectos actuales de la sarcoidosis / Current aspects of sarcoidosis

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[Propionibacterium granulosum bare-metal stent infection after drug-eluting balloon]. / Infection de stent artériel périphérique à Propionibacterium granulosum après angioplastie au ballon actif.

INTRODUCTION: Bare-metal stents are used to treat arterial stenotic lesions. Morbidity and mortality are less important compared with other techniques. Drug-eluting balloons are often used to treat stent stenosis. We reported the case of a bare-metal stent infection after drug-eluting balloon and a review on the subject. MATERIAL AND METHOD: Two weeks after percutaneous transluminal angioplasty with paclitaxel-eluting balloon and a bare-metal stent, our patient presented an infection of the stent. Diagnosis was based on the clinical presentation, positron emission tomography findings and isolation of Propionibacterium granulosum in repeated blood cultures. Adapted antibiotic therapy was given for three months with removal of the surgical bare-stent. Antibiotic therapy was interrupted after a second positron emission tomography. A literature search (PubMed and Cochrane) was performed on the subject. RESULTS: We found 49 cases of peripheral bare-metal stent infection including our patient. This is a rare but serious complication with a high morbidity (25% amputation rate) and mortality (30%). It seems to be underestimated. Treatment is based on surgical ablation of the bare-metal stent and intravenous antibiotics. The role of the paclitaxel-eluting balloon is not clearly established but some authors believe that it can produce a local immunosuppression. CONCLUSION: We report the first case of bare-metal stent infection after paclitaxel-eluting balloon. This complication is rare and difficult to diagnose. Manifestations are often limited to skin signs. Functional and vital prognosis is poor.

Chorioamnionitis and sternoclavicular septic arthritis after drainage of Bartholin gland abscess.

BACKGROUND: Complications after drainage of Bartholin gland abscesses in pregnancy are rare. CASE: A 29-year-old primigravid at 35 weeks of gestation with dichorionic-diamniotic twins underwent Bartholin gland abscess drainage. Afterward, she reported shoulder pain and became febrile. Examination revealed maternal and fetal tachycardia with abdominal tenderness consistent with chorioamnionitis, and she underwent delivery. Blood cultures grew Escherichia coli, and antibiotics were begun. Her shoulder pain worsened, and examination demonstrated inflammation over the sternoclavicular joint. Fluid aspirate of this joint grew E coli. She experienced improvement after aspiration and was discharged home on antibiotics. CONCLUSION: Although rare, severe consequences can result from Bartholin gland abscesses in pregnant patients, including sepsis and septic arthritis. Close clinical follow-up should be considered in pregnant patients undergoing abscess drainage.

[Eye infections associated with ocular implants]. / Infecciones oculares asociadas a los implantes oculares.

Postoperative endophthalmitis associated with intraocular lens implantation is one of the most severe complications of cataract surgery. The prevalence of endophthalmitis following these procedures reported in several multicenter studies over the last decades is 0.05% to 0.32%. Currently, general consensus measures are available to prevent this serious complication. Abiotic biofilm formation with adhesion of pathogens on the surface of intraocular devices is a novel theory that is little understood, but widely accepted to explain the pathophysiologic aspects of intraocular infection. Bacterial adhesion on intraocular lenses has been observed in clinical practice and investigated with several in vitro approaches in various experimental conditions. Improvements in the surgical techniques used in cataract surgery and the advent of new antimicrobial agents with a wider spectrum of action and better penetration in the eye, have resulted in significant advances in the prevention and treatment of intraocular implant-related infection.

Safety assessment of dairy microorganisms: Propionibacterium and Bifidobacterium.

The genera Propionibacterium and Bifidobacterium are clustered in the class Actinobacteria and form the anaerobic branch of coryneform bacteria. The dairy propionibacteria comprising four species P. freudenreichii, P. acidipropionici, P. jensenii and P. thoenii are industrially important as starter cultures in hard-cheese ripening and recently also as protective bio-preservatives and probiotics. These four species are considered as safe whereas cutaneous Propionibacterium species (also named "acnes group") are pathogens. In contrast, bifidobacteria in fermented dairy products and milk powder are exclusively used as probiotics; selected strains of several species (out of more than thirty) contribute to this task. It has been only rarely found that commensal bifidobacteria have been connected with certain dental and other infections. Consequently, only one single species, Bifidobacterium dentium, is recognized as pathogenic. Genome sequence analysis of Bifidobacterium longum and molecular biological analysis of other probiotic strains confirmed so far the absence of virulence and pathogenecity factors. However, tetracycline resistance genes tet(W), although probably not easy transferable, were found in Bifidobacterium strains, also in Bifidobacterium animalis subsp. lactis, the worldwide most used industrial strain. Conclusively, strains from the Propionibacterium and Bifidobacterium species in dairy food generally represent so far no health hazards.

Láser de colorante pulsado en el tratamiento del acné. Estudio de la eficacia clínica y mecanismo de acción / Pulsed dye laser treatment of acne. Study of clinical efficacy and mechanism of action

Introducción. El acné vulgar es una enfermedad multifactorial de la unidad pilosebácea caracterizada por la aparición de lesiones inflamatorias (pápulas, pústulas, quistes) y/o no inflamatorias (comedones cerrados y abiertos) que pueden evolucionar al desarrollo de cicatrices. El aumento de las resistencias bacterianas, los efectos adversos y teratogenicidad de los retinoides y la falta de respuesta a tratamientos habituales llevan a la necesidad de investigar nuevas opciones terapéuticas para el acné. Material y métodos. Estudiamos a 36 pacientes con acné vulgar de grado leve a moderado. Realizamos tratamiento cada 4 semanas utilizando un láser de colorante pulsado de 585 nm de longitud de onda y 350 microseg de duración de pulso. Resultados. A las doce semanas de tratamiento se observa descenso del 27 % de lesiones no inflamatorias y de un 57 % de lesiones activas. El tratamiento fue bien tolerado y considerado como positivo, en cuanto a curación, en 25 pacientes. Conclusiones. El láser de colorante pulsado mejora principalmente las lesiones inflamatorias del acné con pocos efectos adversos

Introduction. Acne vulgaris is a multifactorial disease of the pilosebaceous unit characterized by the development of inflammatory (papules, pustules, cysts) and/or non inflammatory lesions (open and closed comedones) that may progress to scars. The increase of bacterial resistances, adverse effects and teratogenicity of retinoids and lack of response to usual therapies have led to investigate new therapeutic alternatives for acne. Material and method. We studied 36 patients with mild to moderate acne vulgaris. We performed treatment every 4 weeks using pulsed dye laser therapy with a wavelength of 585 nm and pulse duration of 350 microseconds. Results. At twelve weeks of treatment a decrease of 27 % of non inflammatory lesions and of 57 % of active lesions was observed. Treatment was well tolerated and considered positive, in terms of healing, in 25 patients. Conclusions. Pulse dye laser therapy mainly improves inflammatory lesions of acne with few adverse effects

The infectivity of sarcoid clinical material and its bacterial content inoculated in CBA mice.

BACKGROUND: Sarcoidosis is a multisystemic disorder that is currently viewed as the consequence of chronic immunological response associating genetic susceptibility and specific environmental or transmissible agents. Relevant evidence, although conflicting, justifies a concern about the involvement of specific pathogens to disease causation. In this study we assessed the infectivity of sarcoid clinical material, and of the pathogens found in it, to normal CBA mice used as a model of an immuno-competent host. MATERIALS AND METHODS: One hundred and eleven mice were inoculated into their footpads with fresh, filtered, and autoclaved, sputum and bronchoalveolar lavage homogenates, collected from patients with sarcoidosis, and with the mycobacterial and propionibacterial pathogens isolated from this material. RESULTS: The total number of positive reactors of the animals that received raw clinical material and the pathogens it contained was statistically significant compared to those of the control groups. However, the number of affected mice per group was in most cases less than 50% and inflammation was almost always mild and local. CONCLUSION: Based on the evidence provided by inoculation of normal CBA mice, some of the material under study, although of mild potency, can be infectious to an immuno-competent host.

Prosthetic joint infection diagnosed postoperatively by intraoperative culture.

The purpose of this study was to assess the outcome of prosthetic joint infection initially diagnosed by multiple positive intraoperative cultures after revision arthroplasty and treated by strategies that include less than 6 weeks of intravenous antimicrobial therapy. Between January 1995 and December 1999, 16 of 509 (3%) episodes of prosthetic joint infection in 16 patients initially were diagnosed by positive intraoperative cultures after revision arthroplasty. Patients were followed up for a median of 1057 days (range, 731-1969 days). The median age of the patients was 65 years, and 65% of patients had revision total hip arthroplasty. Coagulase-negative staphylococci and Propionibacterium spp were the main pathogens identified. Intravenous antimicrobial therapy was used in 81% of patients and chronic oral suppression was used in 56% of patients. Three patients received no antimicrobial therapy. The median duration of intravenous antimicrobial therapy was 28 days (range, 2-42 days). The 5-year survival free of treatment failure for the 16 episodes was 89%. These results suggest a favorable outcome of prosthetic joint infections because of low virulence pathogens initially diagnosed as positive intraoperative cultures after revision arthroplasty with a variety of medical treatment strategies, including strategies that contain less than 6 weeks intravenous antimicrobial therapy.

Perianal abscess caused by Propionibacterium avidum in a cirrhotic patient.

We describe the first case of community-acquired Propionibacterium avidum subcutaneous tissue infection in a cirrhotic patient. A 70-year-old Chinese male with a 2-year history of hepatitis B virus-induced chronic liver failure and hemorrhoidectomy 17 months previously presented with a painful left buttock abscess, which was culture positive for P. avidum. Being a normal flora of skin with low pathogenicity, there have been only 3 case reports on P. avidum infection, all associated with surgical intervention within 2 to 6 weeks before the onset of P. avidum infection. We hereby review the literature on P. avidum summarizing

Propionibacterium propionicum and infections of the lacrimal apparatus.

Analysis of the clinical details associated with 26 referred isolates of Propionibacterium propionicum revealed the marked propensity of this anaerobe to be involved with infections of the lacrimal apparatus; 18 (69%) of the 26 referred isolates were from cases of canaliculitis in which this organism was regarded as the significant pathogen. Further analysis of data showed a significant correlation with the sex of the patient. Of the 18 cases of canaliculitis, the sex of the patient was reported in 16; 14 (88%) of these 16 patients were females (P < .005). The age of 13 of the 18 patients with canaliculitis was known (mean, 61.6 years; range, < 1-80 years); it appears from these cases that P. propionicum lacrimal infections are more common in later life. None of the referred isolates were identified as Actinomyces species. Despite the fact that infection of the lacrimal apparatus is known as ocular actinomycosis, it appears that P. propionicum is more frequently associated with the condition than are true Actinomyces species.

Pathogenicity of Actinomyces israelii and Arachnia propionica: experimental infection in guinea pigs and phagocytosis and intracellular killing by human polymorphonuclear leukocytes in vitro.

Strains of Actinomyces israelii and Arachnia propionica, isolated from clinical cases of failed endodontic therapy, were examined for: (i) their ability to survive and establish themselves in the soft connective tissue that grew into subcutaneously implanted tissue cages in guinea pigs; (ii) cell-surface hydrophobicity; and (iii) phagocytosis and killing by human polymorphonuclear leukocytes (PMNs) under aerobic and anaerobic conditions. Bacteria were inoculated into the tissue cages in guinea pigs and the cage contents were retrieved after 1, 7, 14 and 21 d for culturing and light and electron microscopy. Both bacterial species showed substantial decline in the number of bacteria by day 7 after the inoculation. Thereafter, the A. israelii strain recovered and, by day 21, had started to increase in number. Light and electron microscopy revealed the formation of typical actinomycotic colonies. A. propionica, on the other hand, continued to decline in number during the entire period of experimental infection and did not form colonies. Both strains were hydrophobic, readily phagocytosed and were efficiently killed by human PMNs under aerobic and anaerobic conditions in vitro. These results suggest that the pathogenicity of A. israelii is due to its ability to establish characteristic cohesive colonies consisting of branching filamentous organisms that are enmeshed in an extracellular matrix. It seems that the organisms existing in such colonies can collectively evade destruction and elimination by host phagocytic cells, whereas in vitro suspensions of the bacteria are easily phagocytosed and efficiently killed by PMNs. With respect to A. propionica, further investigations are necessary to understand its pathogenicity.

Diphtheroids as ocular pathogens.

Unlike Corynebacterium diphtheriae and Propionibacterium acnes, the pleomorphic gram-positive rods known as diphtheroids are generally regarded as nonpathogenic contaminants of the human external eye. We reviewed five years of microbiology records at Wills Eye Hospital and studied a series of eight cases of apparently infectious keratitis associated with heavy growth of diphtheroids on cultures of ulcer scrapings. All of these cases included indolent ulcers that occurred almost exclusively in elderly patients (mean age, 72 years; range, 11 to 92 years). All patients had preexisting ocular conditions that compromised the corneal surface such as exposed corneal sutures, eyelid surgery, aphakic extended wear contact lenses, viral keratitis, and diabetes mellitus. No other pathogens were isolated. All infections responded well to antibiotic therapy with all organisms sensitive to cefazolin and all but one sensitive to gentamicin.

Microbial ecology of the skin.

Humans exist in an environment replete with microorganisms, yet only a few of these microorganisms become residents on the skin surface. These resident flora and the skin constitute a complex ecosystem in which organisms adapt to changes in the microenvironment and to coactions among microorganisms. The skin possesses an assortment of protective mechanisms to limit colonization, and the survival of organisms on the surface lies in part in the ability of the organisms to resist these mechanisms. Microbial colonization on the skin adds to the skin's defense against potentially pathogenic organisms. Although microbes normally live in synergy with their hosts, at times colonization can lead to clinical infection. Common infections consist of superficial infections of the stratum corneum or appendages, which can respond dramatically to therapy but commonly relapse. In rare circumstances these infections can be severe, particularly in immunocompromised patients or hospitalized patients with indwelling foreign devices.

Propionibacterium avidum as the etiologic agent of splenic abscess.

Propionibacterium avidum was isolated from an intrasplenic abscess in a patient recovering from coronary artery bypass surgery. This organism has not previously been reported as an etiologic agent of splenic abscess nor has splenic abscess been described as a complication of coronary bypass surgery. This report emphasizes the potential pathogenicity of normal microbial flora following surgical manipulation.