Propionibacterium acnes as a cause of aggressive aortic valve endocarditis and importance of tissue grinding: case report and review

Ocular Bacterial Infections: A Ten-Year Survey and Review of Causative Organisms Based on the Oklahoma Experience

Ocular infections can be medical emergencies that result in permanent visual impairment or blindness and loss of quality of life. Bacteria are a major cause of ocular infections. Effective treatment of ocular infections requires knowledge of which bacteria are the likely cause of the infection. This survey of ocular bacterial isolates and review of ocular pathogens is based on a survey of a collection of isolates banked over a ten-year span at the Dean McGee Eye Institute in Oklahoma. These findings illustrate the diversity of bacteria isolated from the eye, ranging from common species to rare and unique species. At all sampled sites, staphylococci were the predominant bacteria isolated. Pseudomonads were the most common Gram-negative bacterial isolate, except in vitreous, where Serratia was the most common Gram-negative bacterial isolate. Here, we discuss the range of ocular infections that these species have been documented to cause and treatment options for these infections. Although a highly diverse spectrum of species has been isolated from the eye, the majority of infections are caused by Gram-positive species, and in most infections, empiric treatments are effective.

A postoperative brain abscess due to Propionibacterium acnes in an immunocompetent adult with incidental discovery

Introduction

and importance: Propionibacterium acnes (P. acnes) is an anaerobic, lipophilic, Gram-positive bacteria of the commensal skin flora. It may also be present on the mouth's mucosa, nose, urogenital tract, and large bowel. P. acnes is an unusual and rare agent of intracerebral abscess although in recent years some publications suggest that its frequency in brain surgery is increasing.

Case presentation

The authors report a case of an incidental cerebral abscess during follow-up imaging in a 63-year-old male patient operated on twice for cerebral meningioma the last of which was 3 months ago without placement of any surgical implant with uneventful postoperative course.

Clinical discussion

P. acnes is still an sunder-appreciated cause of post-neurosurgical infection. Time between neurosurgery and infection is variable ranging from few months to many years. Its culture time is long, with currently an average time to positivity of six days (2-15 days), justifying prolonged cultures.

Conclusion

Intracranial infections by P. acnes are not quite frequent. We emphasize the need to send samples for culture of anaerobes in this type of complications before giving a negative result.

Occult prosthetic aortic valve endocarditis caused by Propionibacterium acnes: a case report

We present an unusual case of occult mechanical aortic valve endocarditis caused by Propionibacterium acnes (P. acnes), which occurred five years after the initial cardiac surgical procedure. The only potential source of this infection from the patient's past medical history was a gastric band removal followed by a gastric bypass surgery, which was performed two years prior to her redo cardiac procedure. The patient's main presenting symptom was progressive dyspnoea with worsening of gradients across the mechanical aortic valve. Of note, she had no cardinal symptoms of infection. The patient underwent redo bioprosthetic aortic valve replacement with aortic root replacement. Prosthetic valve cultures grew P. acnes, while blood cultures remained negative. She was started on intravenous antibiotics for six weeks and her postoperative course was uneventful. She remained symptom-free six months postoperatively. This case opens the discussion for the importance of administering antibiotics prophylaxis for endocarditis in patients with prosthetic heart valves undergoing gastric procedures.

A Prospective Study to Assess the Optimal Incubation Times for Culture and Aerobic Bacterial Profile in Prosthetic Joint Infections

Introduction With an increase in the number of total joint arthroplasties, the count of prosthetic joint infections (PJIs) is also increasing and has become a nightmare for an orthopaedic surgeon. Microbiological diagnosis is important for administering definitive antimicrobial treatment. Negative culture reports hamper patient management and prolonged incubation periods have increased the culture yield but at the risk of culture contamination in conventional microbiology settings. Thus, we aimed to optimize the best incubation time for culture and the aerobic bacterial profile of PJIs.

Material and Methods Over a year, samples from clinically suspected PJI patients were collected and processed for culture using standard techniques. The samples were incubated for up to 10 days with daily subculturing on to solid media. The bacterial isolates were identified and antibiotic susceptibility was performed.

Results Out of 200 patients, 105 were included in the study and samples were collected in triplicate. In 70 cases culture was positive and 35 were culture negative PJIs. Mean incubation days to culture positivity was 3.6 days with 97.14% culture positivity seen by the seventh day of incubation. Twenty-four percent methicillin-resistant Staphylococcus aureus , and more than 50% extended spectrum β lactamase producing Klebsiella pneumoniae and Escherichia coli were isolated.

Discussion Culture positivity in PJIs provides definitive evidence of infection and guides the treatment. Increasing the incubation times can help in maximizing the culture yield, and we found that 97.14% pathogens grew within 7 days of incubation. Prolonging it further would not provide an added advantage especially in a resource-constraint setting.

Unravelling the eco-specificity and pathophysiological properties of Cutibacterium species in the light of recent taxonomic changes

In 2016, a new species name Cutibacterium acnes was coined for the well-documented species, Propionibacterium acnes, one of the most successful and clinically important skin commensals. The nomenclatural changes were brought about through creation of the genus Cutibacterium, when a group of propionibacteria isolates from the skin were transferred from the genus Propionibacterium and placed in the phylum Actinobacteria. Almost simultaneously, the discovery of two novel species of Cutibacterium occurred and the proposal of three subspecies of C. acnes were reported. These dramatic changes that occurred in a long-established taxon made it challenging for the non-specialist to correlate the huge volume of hitherto published work with current findings. In this review, we aim to correlate the eco-specificity and pathophysiological properties of these newly circumscribed taxa. We envisage that this information will shed light on the pathogenic potential of new isolates and enable better assessment of their clinical importance in the foreseeable future. Currently, five species are recognized within the genus: Cutibacterium acnes, Cutibacterium avidum, Cutibacterium granulosum, Cutibacterium modestum (previously, "Propionibacterium humerusii"), and Cutibacterium namnetense. These reside in different niches reflecting their uniqueness in their genetic makeup. Their pathogenicity includes acne inflammation, sarcoidosis, progressive macular hypomelanosis, prostate cancer, and infections (bone, lumbar disc, and heart). This is also the case for the three newly described subspecies of C. acnes, which are C. acnes subspecies acnes (C. acnes type I), subspecies defendens (C. acnes type II), and subspecies elongatum (C. acnes type III). C. acnes subspecies acnes is related to inflamed acne and sarcoidosis, while subspecies defendens to prostate cancer and subspecies elongatum to progressive macular hypomelanosis. Because the current nomenclature is based upon polyphasic analyses of the biochemical and pathogenic characteristics and comparative genomics, it provides a sound basis studying the pathophysiological roles of these species.

Cardiac Tamponade Caused by Cutibacterium acnes: An Updated and Comprehensive Review of the Literature

Bacterial pericarditis is a critical diagnosis caused by a wide range of organisms including Streptococcus pneumoniae and other anaerobic organisms like Cutibacterium acnes which has been gaining more importance as a causative organism. Cutibacterium species are Gram-positive microaerophilic rods that constitute part of the normal flora of skin and mucosal membranes. The incidence of pericarditis caused by this organism is underreported as it is often dismissed as a skin flora contaminant. However, if left untreated, Cutibacterium acnes can cause pericarditis with serious complications. In this paper, we present a comprehensive review of the literature regarding pericarditis caused by Cutibacterium acnes along with a case presentation from our institution. In our institution, a 20-year-old man with history of atrial septal defect presented with chest pain radiating to the back along with symptoms of upper respiratory tract infection including headaches and myalgia. Electrocardiogram was remarkable for diffuse low-voltage waves. Echocardiography revealed a large pericardial effusion with tamponade features. Pericardiocentesis drained 1.2 L of milky fluid. Pericardial fluid analysis grew Cutibacterium acnes after being cultured for 8 days. The patient received 3 weeks of IV penicillin followed by 3 weeks of oral amoxicillin along with nonsteroidal anti-inflammatory agents and colchicine with no recurrence. Pericarditis caused by Cutibacterium acnes requires a high clinical suspicion since isolation of this organism can be dismissed as a skin flora contaminant. Literature review reveals that this infection may be underdiagnosed and underreported. Prompt diagnosis may lead to timely initiation of antibiotics which can help prevent devastating complications like constrictive pericarditis. Prospective studies are needed to evaluate the true incidence and prevalence of this disease.

Acne on the Valve: Two Intriguing Cases of Cutibacterium Acnes Endocarditis

Cutibacterium acnes is a skin commensal which is most often regarded as a contaminant when detected on blood cultures. In rare instances, it may be the causative pathogen in severe systemic illnesses. Subacute endocarditis, especially of prosthetic valves and devices, is an important grave pathology caused by Cutibacterium acnes. Herein we report two cases of prosthetic valve endocarditis with varied presentations as valve dehiscence with a "rocking" prosthetic valve apparatus in one encounter and as a septic embolic stroke in the second encounter. Although a rare cause of endocarditis, it becomes an especially important entity in patients with prosthetic devices and should be high in the list of differentials.

Cutibacterium acnes prosthetic joint infection: Diagnosis and treatment

Cutibacterium acnes is a commensal skin bacterium, regularly implicated in prosthetic joint infection, particularly of the shoulder. Diagnosis has been improved by progress in bacteriological techniques: longer culture time, liquid medium culture, MALDI-TOF mass spectrography, and universal 16S rRNA PCR, associated by some authors to sonication of ablated implants. C. acnes pathogenicity involves many virulence factors, notably including biofilm formation. C. acnes may lead to infection that is clinically evident or, frequently, relatively asymptomatic. C. acnes is an anaerobic Gram-positive bacterium, susceptible to many antibiotics that are regularly used in bone and joint infection: beta-lactams, quinolone, rifampicin and clindamycin. It shows increasing resistance to clindamycin and natural resistance to metronidazole. Treatment is medical and surgical, associating synovectomy or complete 1- or 2-step revision depending on time to treatment, and antibiotic therapy. Antibiotic therapy is typically for three months with an initial 2-6 weeks' intravenous phase. Prognosis is generally favorable with well-conducted treatment. Late discovery of positive samples after apparently aseptic implant change is an at-risk situation, usually managed by antibiotic therapy, but with late initiation and hence increased risk of failure. Adverse secondary progression requires repeat revision under good conditions.

Constrictive pericarditis caused by Cutibacterium (Propionibacterium) acnes: A case report and review of literature

Constrictive and effusive-constrictive pericarditis are rare cardiac disorders. Only rarely are the conditions caused by purulent infection, and even more infrequently by anaerobe bacteria. We describe a case of constrictive – and effusive-constrictive pericarditis due to Cutibacterium (formerly Propionibacterium) acnes in a 75-year old, immunocompetent and previously healthy patient without any predisposition. The patient was successfully treated with subtotal pericardiectomy and beta-lactam antibacterials. C. acnes was the only infectious agent recovered from samples of cultured pericardial tissue.

C. acnes is a microaerophilic, Gram-positive anaerobic bacillus that is a part of the normal flora. In symptomatic patients, however, positive samples should be considered as clinically relevant and not dismissed as contamination. Due to the low virulence, the capability of adherence and biofilm formation of C. acnes, diagnosing C. acnes constrictive pericarditis may be difficult. In the context of compatible symptoms, the incubation time of clinical samples should be prolonged or supplemented by polymerase chain reaction techniques. Parenteral beta-lactam antibacterials are considered the drugs of choice.

Severe constrictive and effusive-constrictive pericarditis caused by C. acnes is rare, but can be seen even in otherwise healthy patients. Prolonged incubation time and polymerase chain reaction techniques may be required in order to confirm diagnosis.

Propionibacterium acnes: Time-to-Positivity in Standard Bacterial Culture From Different Anatomical Sites

BACKGROUND

Propionibacterium acnes infections are likely under-recognized and underreported. This is partly because of low clinical suspicion, perceived non-pathogenicity, or lack of adequate culture incubation time. We conducted a study to assess the optimal incubation period to recover P. acnes from specimens acquired during the workup of suspected clinical infections.

METHODS

A 5-year retrospective chart review was conducted between January 2010 and December 2014 at a single tertiary-care hospital. All patient cases from which P. acnes was recovered were included for analysis. Source of infection, antibiotic use, and culture time-to-positivity (TTP) were recorded.

RESULTS

Implanted devices comprised the single most common source of P. acnes infection. In the majority of cases, P. acnes was the only organism identified. The mean incubation TTP for all isolates was 5.73 days.

CONCLUSIONS

Standard 5-day culture incubation periods are insufficient to recover P. acnes. As a result, P. acnes is likely a much more common etiology of a variety of clinical infections than previously reported.

Bacterial Communities Associated with Atherosclerotic Plaques from Russian Individuals with Atherosclerosis

Atherosclerosis is considered a chronic disease of the arterial wall and is the major cause of severe disease and death among individuals all over the world. Some recent studies have established the presence of bacteria in atherosclerotic plaque samples and suggested their possible contribution to the development of cardiovascular disease. The main objective of this preliminary pilot study was to better understand the bacterial diversity and abundance in human atherosclerotic plaques derived from common carotid arteries of individuals with atherosclerosis (Russian nationwide group) and contribute towards the further identification of a main group of atherosclerotic plaque bacteria by 454 pyrosequencing their 16S ribosomal RNA (16S rRNA) genes. The applied approach enabled the detection of bacterial DNA in all atherosclerotic plaques. We found that distinct members of the order Burkholderiales were present at high levels in all atherosclerotic plaques obtained from patients with atherosclerosis with the genus Curvibacter being predominant in all plaque samples. Moreover, unclassified Burkholderiales as well as members of the genera Propionibacterium and Ralstonia were typically the most significant taxa for all atherosclerotic plaques. Other genera such as Burkholderia, Corynebacterium and Sediminibacterium as well as unclassified Comamonadaceae, Oxalobacteraceae, Rhodospirillaceae, Bradyrhizobiaceae and Burkholderiaceae were always found but at low relative abundances of the total 16S rRNA gene population derived from all samples. Also, we found that some bacteria found in plaque samples correlated with some clinical parameters, including total cholesterol, alanine aminotransferase and fibrinogen levels. Finally, our study indicates that some bacterial agents at least partially may be involved in affecting the development of cardiovascular disease through different mechanisms.

Isolation of Propionibacterium acnes among the microbiota of primary endodontic infections with and without intraoral communication

Objectives

The presence of opportunistic pathogens such as Propionibacterium acnes (P. acnes) may contribute to the endodontic pathology. The presence of P. acnes may be influenced by different endodontic conditions.

The aims of the study were firstly, to identify P. acnes within the whole cultivable microbiota of primary endodontic infections, to investigate which P. acnes phylotypes predominate in such infections and secondly to determine if the presence of an “open” communication (e.g. a sinus) can be associated with the isolation of P. acnes from the root canal.

Material and methods

The predominant cultivable microbiota of 15 primary endodontic lesions (7 without communication with the oral environment and 8 with an open communication) were identified using partial 16S ribosomal RNA (rRNA) gene sequence analysis. The identification of the organism was determined by interrogating the Human Oral Microbiome Database. The P. acnes isolates were typed on the basis of the recA gene sequence comparison. A neighbor-joining tree was constructed using MEGA 4.1 with the inclusion of known recA sequences.

Results

There was no difference in the number of species identified from lesions without communication (5.86 ± 3.7) and those with communication (5.37 ± 3.6) (P > 0.05). PCR-based 16S rRNA gene sequencing revealed P. acnes as the most prevalent isolate recovered from lesions with communication. recA gene sequencing revealed two phylogenetic lineages present in lesion with communication, with mainly type I (further split into type IA and type IB) and type II.

Conclusions

The presence of P. acnes as opportunistic pathogens has been confirmed and may sustain the traits observed in specific clinical presentations.

Clinical relevance

Clinical management of open lesions may require further disinfection to eliminate opportunistic bacteria.

Propionibacterium acnes Recovered from Atherosclerotic Human Carotid Arteries Undergoes Biofilm Dispersion and Releases Lipolytic and Proteolytic Enzymes in Response to Norepinephrine Challenge In Vitro

In the present study, human atherosclerotic carotid arteries were examined following endarterectomy for the presence of the Gram-positive bacterium Propionibacterium acnes and its potential association with biofilm structures within the arterial wall. The P. acnes 16S rRNA gene was detectable in 4 of 15 carotid artery samples, and viable P. acnes was one among 10 different bacterial species recoverable in culture. Fluorescence in situ hybridization analysis of 5 additional atherosclerotic carotid arteries demonstrated biofilm bacteria within all samples, with P. acnes detectable in 4 samples. We also demonstrated that laboratory-grown cultures of P. acnes biofilms were susceptible to induction of a biofilm dispersion response when challenged with physiologically relevant levels of norepinephrine in the presence of iron-bound transferrin or with free iron. The production and release of lipolytic and proteolytic extracellular enzymes by P. acnes were shown to increase in iron-induced dispersed biofilms, and these dispersion-induced P. acnes VP1 biofilms showed increased expression of mRNAs for the triacylglycerol lipases PPA2105 and PPA1796 and the hyaluronate lyase PPA380 compared to that in untreated biofilms. These results demonstrate that P. acnes can infect the carotid arteries of humans with atherosclerosis as a component of multispecies biofilms and that dispersion is inducible for this organism, at least in vitro, with physiologically relevant levels of norepinephrine resulting in the production and release of degradative enzymes.

Improved microbiological diagnostic due to utilization of a high-throughput homogenizer for routine tissue processing

Tissue specimens are valuable materials for microbiological diagnostics and require swift and accurate processing. Established processing methods are complex, labor intensive, hardly if at all standardizable, and prone to incorporate contaminants. To improve analyses from tissue samples in routine microbiological diagnostics, by facilitating, fastening, and standardizing processing as well as increasing the microbial yield, performance of Precellys 24 high-throughput tissue homogenizer was evaluated. Therefore, tissue samples were artificially inoculated with Staphylococcus aureus, Escherichia coli, and Candida albicans in 3 different ways on the surface and within the material. Microbial yield from homogenized samples was compared to direct plating method. Further, as proof of principle, routine tissue samples from knee and hip endoprosthesis infections were analyzed. The process of tissue homogenization with Precellys 24 homogenizer is easy and fast to perform and allows for a high degree of standardization. Microbial yield after homogenization was significantly higher as compared to conventional plating technique.

Propionibacterium acnes: from commensal to opportunistic biofilm-associated implant pathogen

Propionibacterium acnes is known primarily as a skin commensal. However, it can present as an opportunistic pathogen via bacterial seeding to cause invasive infections such as implant-associated infections. These infections have gained more attention due to improved diagnostic procedures, such as sonication of explanted foreign materials and prolonged cultivation time of up to 14 days for periprosthetic biopsy specimens, and improved molecular methods, such as broad-range 16S rRNA gene PCR. Implant-associated infections caused by P. acnes are most often described for shoulder prosthetic joint infections as well as cerebrovascular shunt infections, fibrosis of breast implants, and infections of cardiovascular devices. P. acnes causes disease through a number of virulence factors, such as biofilm formation. P. acnes is highly susceptible to a wide range of antibiotics, including beta-lactams, quinolones, clindamycin, and rifampin, although resistance to clindamycin is increasing. Treatment requires a combination of surgery and a prolonged antibiotic treatment regimen to successfully eliminate the remaining bacteria. Most authors suggest a course of 3 to 6 months of antibiotic treatment, including 2 to 6 weeks of intravenous treatment with a beta-lactam. While recently reported data showed a good efficacy of rifampin against P. acnes biofilms, prospective, randomized, controlled studies are needed to confirm evidence for combination treatment with rifampin, as has been performed for staphylococcal implant-associated infections.

Propionibacterium acnes: an underestimated pathogen in implant-associated infections

The role of Propionibacterium acnes in acne and in a wide range of inflammatory diseases is well established. However, P. acnes is also responsible for infections involving implants. Prolonged aerobic and anaerobic agar cultures for 14 days and broth cultures increase the detection rate. In this paper, we review the pathogenic role of P. acnes in implant-associated infections such as prosthetic joints, cardiac devices, breast implants, intraocular lenses, neurosurgical devices, and spine implants. The management of severe infections caused by P. acnes involves a combination of antimicrobial and surgical treatment (often removal of the device). Intravenous penicillin G and ceftriaxone are the first choice for serious infections, with vancomycin and daptomycin as alternatives, and amoxicillin, rifampicin, clindamycin, tetracycline, and levofloxacin for oral treatment. Sonication of explanted prosthetic material improves the diagnosis of implant-associated infections. Molecular methods may further increase the sensitivity of P. acnes detection. Coating of implants with antimicrobial substances could avoid or limit colonization of the surface and thereby reduce the risk of biofilm formation during severe infections. Our understanding of the role of P. acnes in human diseases will likely continue to increase as new associations and pathogenic mechanisms are discovered.

Optimization of microbial screening for cord blood

BACKGROUND

Collection and processing of cord blood (CB) is associated with significant risk of contamination; hence standards mandate microbial screening of the final product. The sensitivity of current methods to evaluate the microbial content of CB is unknown, given the small volume tested and reduced sensitivity of pediatric bottles. Hence, this study was undertaken to evaluate an optimal microbial screening method.

STUDY DESIGN AND METHODS

CB was collected using a closed system then spiked with organisms at 1 or 10 colony-forming units (CFUs)/mL. Samples were screened using culture bottles (BacT/ALERT, bioMérieux; and BACTEC, Becton Dickinson). Several methods were evaluated with different combinations of inoculated bottles (adult vs. pediatric), sample types (plasma discard, red blood cell [RBC] discard, or final product), and sample volumes.

RESULTS

Of 94 cord blood units (CBUs) spiked with organisms before screening, 81% tested positive for contamination overall. Screening of CB in pediatric bottles resulted in equivalent detection rates on the BacT/ALERT and BACTEC systems (33% at 1 CFU/mL and 73% at 10 CFUs/mL, respectively). However, the pediatric bottle screen only detected 15% of obligate anaerobes. A combined fraction method showed superior detection (71%) compared to the plasma fraction (27%) and resulted in optimal anaerobic detection.

CONCLUSIONS

This study demonstrates that the optimal microbial screening method for CB includes testing a combination of discard fractions (plasma and RBCs) in addition to final product using an automated culture system. Inoculating a small sample of final product in a pediatric bottle is suboptimal for microbial detection and may lead to distribution of contaminated CB for transplantation.

Optimizing culture methods for diagnosis of prosthetic joint infections: a summary of modifications and improvements reported since 1995

Improving diagnosis of prosthetic joint infections (PJIs) has become an increasing challenge due to a steadily rising number of patients with prosthetic implants. Based on a systematic literature search we have ascertained the evidence base for improvement of culture diagnosis. We searched PubMed/MEDLINE using the medical subject heading (MeSH) 'prosthesis-related infections' 1995 through 2010 without further restrictions. An analogous search was conducted for ISI Web of Knowledge. A total of 1409 reports were screened for original results, obtained by methods described in sufficient detail to make replication possible. We gave priority to methods for sample preparation, culture media, culture methods and incubation time. Clinical sensitivity and specificity were calculated where possible. We found evidence to support superiority of cultures obtained from the diluent after sonication of prosthetic implants in comparison with culturing tissue biopsies. Sonication parameters and accessory steps have been studied extensively, and thresholds for significant growth have been defined. Conversely, methods for processing of soft tissue biopsies have been studied to a limited extent. Culture of synovial fluid in blood culture vials has been shown to be more sensitive (90-92 %) than intraoperative swab cultures (68-76 %) and tissue cultures (77-82 %). Formal evaluation of agar media for culturing PJI specimens seemed to be lacking. The polymicrobial nature of PJIs supports the routine use of an assortment of media suitable for recovery of fastidious, slow-growing, anaerobic and sublethally damaged bacteria. A number of studies supported an incubation period for up to 14 days. Although we identified evidence-based improvements of culture methods, there is a need for more studies especially with regard to tissue biopsies. Culturing remains an important means to identify and characterize pathogenic micro-organisms and supplements the increasing number of culture-independent assays.

Granulomatous Propionibacterium acnes infection after trauma surgery

We report here a rare case of infection caused by Propionibacterium acnes following trauma surgery: a 36-year-old male, accident victim was admitted to the hospital because of polytrauma. He underwent a long-drawn-out surgical intervention and after a free-muscle transfer using the rectus femoris muscle, signs of inflammation were detected in the affected area. Microbiological examination of the wound revealed the presence of P. acnes as the only etiological agent of this infection. Adequate antibiotic treatment with penicillin had been started right after the positive microbiological result. Our data confirm the pathogenic potential of P. acnes in late post-surgical infections, and suggest a proper therapeutic approach with intravenous antibiotics and surgical removal of the infected tissue.

Clinical significance of Propionibacterium acnes recovered from blood cultures: analysis of 524 episodes

Of 522 patients with Propionibacterium acnes bacteremia (PAB), 18 (3.5%) had clinically significant PAB. Of these 18 patients, 10 (55.6%) had hospital-acquired bacteremia and 6 (33.3%) had undergone invasive procedures before development of PAB. One patient with a ventricular septal defect presented with infective endocarditis. After the exclusion of 1 patient whose outcome was not available, the overall mortality rate was 5.9% (1/17).

Propionibacterium acnes and Staphylococcus epidermidis isolated from refractory endodontic lesions are opportunistic pathogens

The predominant cultivable microbiota from 20 refractory endodontic lesions (9 with abscesses and 11 without abscesses) were determined, and Propionibacterium acnes and Staphylococcus epidermidis were among the most predominant organisms. The number of species identified from lesions with abscesses (14.1 ± 2.6) was significantly greater (P < 0.001) than the number from lesions without abscesses (7.4 ± 5.9). Comparison of perioral isolates using repetitive extragenic palindromic PCR of the same species from the same subjects demonstrated that the endodontic and skin populations were significantly different. The P. acnes isolates were typed on the basis of recA gene sequence comparison, and only three types (types I, II, and III) were identified among 125 isolates examined. However, we found that type I (type IA and IB) isolates were primarily isolated from the skin, while types II and III were significantly more likely to be isolated from the endodontic lesions (P < 10(-10)). We found that the robustness of the recA phylotypes was not strong by comparing the partial gene sequences of six putative virulence determinants, PAmce, PAp60, PA-25957, PA-5541, PA-21293, and PA-4687. The resulting neighbor-joining trees were incongruent, and significant (phi test; P = 2.2 × 10(-7)) evidence of recombination was demonstrated, with significant phylogenetic heterogeneity being apparent within the clusters. P. acnes and S. epidermidis isolated from refractory endodontic infections, with or without periapical abscesses, are likely to be nosocomial infections.

Validity of frozen sections for analysis of periprosthetic loosening membranes

Clinical findings and blood parameters often are inconclusive in patients with periprosthetic joint infections. Among the accepted criteria for diagnosis, histologic analysis of debrided tissue can detect infection in most cases but does not allow intraoperative decision making. We evaluated the validity of intraoperative frozen sections for detection of prosthetic infections. The results from frozen and permanent sections of periprosthetic membranes of 64 consecutive patients who underwent exchange procedures after hip arthroplasty were compared using the histopathologic consensus classification of Morawietz et al. Blood parameters (erythrocyte sedimentation rate, leukocyte count, C-reactive protein) and culture results of preoperatively aspirated joint fluid and intraoperative tissue samples were correlated with the histologic results. In 50 patients (78.1%), agreement was found between the frozen and permanent sections. Two patients (3.1%) revealed a discrepancy between the two histologic methods. In 12 patients (18.8%), a diagnosis was not possible based on the frozen sections because the tissue samples were not representative enough for definite classification. For the analyzable cases (n = 52), the sensitivity of frozen-section histologic analysis was 86.6%, specificity 100%, and accuracy 96.2%. Our data support a recommendation for use of intraoperative frozen sections for diagnosis of septic versus aseptic loosening in revision hip surgery.

LEVEL OF EVIDENCE

Level II, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Propionibacterium acnes infection after shoulder arthroplasty: a diagnostic challenge

HYPOTHESIS

This study reviewed a series of patients diagnosed with Propionibacterium acnes infection after shoulder arthroplasty in order to describe its clinical presentation, the means of diagnosis, and provide options for treatment.

MATERIALS AND METHODS

From 2002 to 2006, 11 patients diagnosed with P acnes infection after shoulder arthroplasty were retrospectively reviewed and analyzed for (1) clinical diagnosis; (2) laboratory data, including white blood cell count, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP); (3) fever; (4) number of days for laboratory growth of P acnes; (5) organism sensitivities; (6) antibiotic regimen and length of treatment; and (7) surgical management. Infection was diagnosed by 2 positive cultures.

RESULTS

Five patients had an initial diagnosis of infection and underwent implant removal, placement of an antibiotic spacer, and staged reimplantation after a course of intravenous antibiotics. In the remaining 6 patients, surgical treatment varied according to the clinical diagnosis. When infection was recognized by intraoperative cultures, antibiotics were initiated. The average initial ESR and CRP values were 33 mm/h and 2 mg/dL, respectively. The average number of days from collection to a positive culture was 9. All cultures were sensitive to penicillin and clindamycin and universally resistant to metronidazole.

DISCUSSION

Prosthetic joint infection secondary to P acnes is relatively rare; yet, when present, is an important cause of clinical implant failure. Successful treatment is hampered because clinical findings may be subtle, many of the traditional signs of infection are not present, and cultures may not be positive for as long as 2 weeks.

Propionibacterium endocarditis: A case series from the International Collaboration on Endocarditis Merged Database and Prospective Cohort Study

Propionibacterium species are occasionally associated with serious systemic infections such as infective endocarditis. In this study, we examined the clinical features, complications and outcome of 15 patients with Propionibacterium endocarditis using the International Collaboration on Endocarditis Merged Database (ICE-MD) and Prospective Cohort Study (ICE-PCS), and compared the results to 28 cases previously reported in the literature. In the ICE database, 11 of 15 patients were male with a mean age of 52 y. Prosthetic valve endocarditis occurred in 13 of 15 cases and 3 patients had a history of congenital heart disease. Clinical findings included valvular vegetations (9 patients), cardiac abscesses (3 patients), congestive heart failure (2 patients), and central nervous system emboli (2 patients). Most patients were treated with beta-lactam antibiotics alone or in combination for 4 to 6 weeks. 10 of the 15 patients underwent valve replacement surgery and 2 patients died. Similar findings were noted on review of the literature. The results of this paper suggest that risk factors for Propionibacterium endocarditis include male gender, presence of prosthetic valves and congenital heart disease. The clinical course is characterized by complications such as valvular dehiscence, cardiac abscesses and congestive heart failure. Treatment may require a combination of medical and surgical therapy.

Chronic prosthetic valve endocarditis due to Propionibacterium acnes: an unexpected cause of prosthetic valve dysfunction

INTRODUCTION AND OBJECTIVES

To determine the characteristics of Propionibacterium acnes prosthetic valve endocarditis (PAPVE).

METHODS

Prospective descriptive study of 16 consecutive cases of PAPVE.

RESULTS

Seven patients developed PAPVE early and 9 developed it late. In all those who developed PAPVE late, there was a history of mucocutaneous barrier manipulation. The delay in diagnosis was >3 months in 75%. The clinical presentation was asymptomatic prosthetic valve dysfunction in 31%, heart failure in 19%, coronary syndrome in 12.5%, fever in 25%, and neurological deficits in 19%. At diagnosis, 62.5% had heart failure and 44% had fever. The predominant echocardiographic finding was prosthesis dysfunction due to dehiscence of metallic aortic valves (6 out of 7) or stenosis of metallic mitral valves (4 out of 7). In 2 of the 3 biological aortic prostheses, dysfunction was due to leaflet distortion. Blood cultures and surgical specimens tested positive after a mean of 11.6 and 12.2 days, respectively. In 2 cases, the diagnosis was confirmed by PCR. The principle intraoperative finding was the presence of abundant grayish pannus. Histology demonstrated the absence of acute inflammatory features. Twelve patients received antibiotic treatment with valve replacement: 7 were cured, 4 experienced early prosthesis dehiscence and 1 relapsed. All 3 patients who were initially treated with antibiotics alone suffered relapses.

CONCLUSIONS

Generally, PAPVE presents as prosthetic valve dysfunction with few symptoms of infection. Prolonged incubation of cultures is essential for diagnosis. Antibiotic treatment provides clinical control but does not eradicate the infection, and valve replacement is necessary for a cure. The postoperative course can be complicated by prosthesis dehiscence.

Infective endocarditis due to Propionibacterium species

Propionibacterium species rarely cause infective endocarditis. When identified in blood cultures, they may be inappropriately disregarded as skin flora contaminants. The purpose of this study was to characterize the clinical presentation and management of endocarditis due to Propionibacterium species. All cases of endocarditis due to Propionibacterium species that were treated at the Mayo Clinic, Rochester, USA were retrospectively reviewed, and the English language medical literature was searched for all previously published reports. Seventy cases, which included eight from the Mayo Clinic, were identified (clinical details were available for only 58 cases). The median age of patients was 52 years, and 90% were males. In 79% of the cases, the infection involved prosthetic material (39 prosthetic valves, one left ventricular Teflon patch, one mitral valve ring, one pulmonary artery prosthetic graft, three pacemakers, and one defibrillator). Blood cultures were positive in 62% of cases. All 22 cases with negative blood cultures were microbiologically confirmed by either positive valve tissue cultures (n = 21) or molecular methods (n = 1). Endocarditis was complicated by abscess formation in 36% of cases. The majority (81%) of patients underwent surgery, either for valve replacement and debridement of a cardiac abscess, or removal of an infected device. Crude in-hospital mortality was 16%. The median duration of postoperative antibiotic treatment was 42 days. Patients were commonly treated with a penicillin derivative alone or in combination with gentamicin. On the basis of the above data, it is recommended that infective endocarditis should be strongly suspected when Propionibacterium species are isolated from multiple blood cultures, particularly in the presence of a cardiovascular device.

Propionibacterium spp. in prosthetic joint infections: a diagnostic challenge

INTRODUCTION

Propionibacterium species are common inhabitants of the skin and usually non-pathogenic for humans. However, Propionibacterium spp. can occasionally cause infections, but are estimated to play a minor role in prosthetic joint infections (PJI). The relative frequency of these anaerobes and their potential to cause surgical site infection may be clinically underestimated. An unknown proportion of these infections might be missed, since little is known about their clinical presentation, and since growth of Propionibacterium spp. in diagnostic samples is often interpreted as contamination. Thus, a hypothesis is being tested, stating that Propionibacterium spp. is not as rare as often reported, and it can cause severe soft-tissue damages in PJI.

MATERIALS AND METHODS

In this retrospective analysis, we reviewed all PJI that had been treated in our institution from 2000 to 2005, and assessed the relative frequency of those caused by Propionibacterium spp. In the identified cases, features that led to the diagnosis (clinical, laboratory, radiological, microbiological and histopathological characteristics) were analysed.

RESULTS

Of 139 cases of prosthetic joint infections, 8(6%) were caused by Propionibacterium spp. Seven patients complained of pain as the main symptom, and four had damaged soft-tissue. Analysis of the diagnostic procedures showed a median of 39% positive samples out of all cultured biopsies (median 9.5 biopsies per case), with a median time-to-positivity of 8 days. Results of histopathological examinations of the periprosthetic tissue correlated well with the clinical courses.

CONCLUSIONS

Our data suggest that Propionibacterium associated prosthetic joint infections occur at a relative frequency that is comparable to many other pathogens. Clinical signs are generally subtle, but the spectrum includes also significant soft-tissue damages. In this study, a median of 9.5 biopsies per case, an incubation time of 14 days, and the aid of histopathological examinations proved to be helpful in establishing the diagnosis.

Diagnosis of periprosthetic infection following total hip arthroplasty--evaluation of the diagnostic values of pre- and intraoperative parameters and the associated strategy to preoperatively select patients with a high probability of joint infection

Background

The correct diagnosis of a prosthetic joint infection (PJI) is crucial for adequate surgical treatment. The detection may be a challenge since presentation and preoperative tests are not always obvious and precise. This prospective study was performed to evaluate a variety of pre- and intraoperative investigations. Furthermore a detailed evaluation of concordance of each preoperative diagnosis was performed, together with a final diagnosis to assess the accuracy of the pre-operative assumption of PJI.

Methods

Between 01/2005 and 02/2007, a prospective analysis was performed in 50 patients, who had a two stage revision because of assumed PJI. Based on clinical presentation, radiography, haematological screening, or early failure, infection was assumed and a joint aspiration was performed. Depending upon these findings, a two stage revision was performed, with intra-operative samples for culture and histological evaluation obtained. Final diagnosis of infection was based upon the interpretation of the clinical presentation and the pre- and intraoperative findings.

Results

In 37 patients a positive diagnosis of PJI could be made definitely. The histopathology yielded the highest accuracy (0.94) in identification of PJI and identified 35 of 37 infections (sensitivity 0.94, specificity 0.94, positive-/negative predictive value 0.97/0.86). Intra-operative cultures revealed sensitivities, specificities, positive-/negative predictive values and accuracy of 0.78, 0.92, 0.96, 0.63 and 0.82. These values for blood screening tests were 0.95, 0.62, 0.88, 0.80, and 0.86 respectively for the level of C-reactive protein, and 0.14, 0.92, 0.83, 0.29 and, 0.34 respectively for the white blood-cell count. The results of aspiration were 0.57, 0.5, 0.78, 0.29, and 0.54.

Conclusion

The detection of PJI is still a challenge in clinical practice. The histopathological evaluation emerges as a highly practical diagnostic tool in detection of PJI. Furthermore, we found a discrepancy between the pre-operative suspicion of PJI and the final post-operative diagnosis, resulting in a slight uncertainty in whether loosening is due to bacterial infection or not. The variation in accuracy of the single tests may influence the detection of PJI. Level of Evidence: Diagnostic Level I.

Propionibacterium acnes lacks the capability to proliferate in platelet concentrates

BACKGROUND AND OBJECTIVES

Propionibacterium acnes is considered to be one of the most frequent contaminants of platelet concentrates (PCs) when anaerobic culture-based detection methods are used. But Propionibacteria are often detected too late when blood products have already been transfused. Therefore, its transfusion relevance is still demanding clarification because studies of the outcome of patients transfused with P. acnes-contaminated PCs are still uncommon. In this study, we monitored clinical effects in patients after transfusion of PCs, which were detected too late in sterility testing. Furthermore, we assessed the bacterial proliferation of Propionibacterium species seeded into PCs to clarify their significance for platelet bacteria screening.

MATERIALS AND METHODS

In the look-back process, we followed the route of the putative contaminated PC units from storage to transfusion. In the in vitro study, PCs were inoculated with 1-100 colony-forming unit (CFU)/ml of clinical isolates of Propionibacteria (n = 10). Sampling was performed during 10-day aerobic storage at 22 degrees C. The presence of bacteria was assessed by plating culture and automated BacT/Alert culture system.

RESULTS

Propionibacterium acnes shows slow or no growth under PC storage conditions. Clinical signs of adverse events after transfusion of potentially contaminated PC units were not reported.

CONCLUSION

Propionibacteria do not proliferate under PC storage conditions and therefore may be missed or detected too late when blood products have already been transfused.

Propionibacterium acnes endocarditis in an adolescent boy suffering from a congenital cardiopathy

Propionibacterium acnes endocarditis is an uncommon infection in pediatrics. We describe a case of P. acnes endocarditis in a 16-year-old boy that occurred 6 months after recurrent surgery for a congenital cardiopathy. Molecular identification of P. acnes was obtained. He recovered from this infection after a surgical treatment and with a prolonged antibiotic regimen including ceftriaxone.

Propionibacterium acnes vertebral osteomyelitis: seek and ye shall find?

The pathogenic potential of Propionibacterium acnes in implant-associated spine infections is increasingly recognized. However, the clinical findings and outcomes associated with this pathogen in nonimplant-associated spine infections are unknown. We retrospectively reviewed nine male patients who met our strict case definition for P. acnes vertebral osteomyelitis to determine whether the laboratory, radiographic, and histopathology found in these infections differs from that typically associated with vertebral osteomyelitis. We also determined clinical outcomes as they related to medical and surgical treatments rendered. Radiographic results, laboratory results, and histopathology results of patients with P. acnes vertebral osteomyelitis were often not those classically described for this disease. Two of the nine patients' imaging examinations did not suggest infection. Five of six patients had normal erythrocyte sedimentation rates at diagnosis. Three of six patients' histopathology did not show evidence of infection. Two patients whose treatment included spinal surgery with implant placement developed relapse of their infection. The remaining seven patients had rapid improvement with antimicrobial therapy. Patients with P. acnes vertebral osteomyelitis may present with atypical findings. Clinicians should be aware of the pathogenic potential of this organism, particularly following invasive spine procedures.

Cardiac Magnetic Resonance Imaging for Detection of an Abscess Associated with Prosthetic Valve Endocarditis: A Case Report

Propionibacterium acnes is an organism frequently isolated in cultures and often dismissed as a contaminant. A patient with a febrile illness and prosthetic aortic valve was suspected of having infectious endocarditis. Magnetic resonance imaging was useful in defining a paravalvular abscess associated with prosthetic valve endocarditis due to Propionibacterium acnes that was then successfully surgically repaired.

Endocarditis caused by Propionibacterium acnes: an easily ignored pathogen

Propionibacterium acnes, which usually considered as a contaminant, has been found to be an emerging pathogen in human diseases. We describe a case of prosthetic valve related endocarditis caused by P. acnes. Sequencing of the genetic coding of 16S ribosomal RNA was used to identify the pathogen and random amplified polymorphic DNA patterns further confirmed the persistent bacteraemia, which help to determine the diagnosis.

Propionibacterium acnes as a cause of prosthetic valve aortic root abscess

Propionibacterium acnes isolates usually have relatively low virulence and are often classified as contaminants when isolated from blood and tissue cultures. We report a patient with Propionibacterium acnes bacteremia and late prosthetic valve endocarditis, complicated by an aortic root abscess.

Endocarditis caused by Propionibacterium species: a report of three cases and a review of clinical features and diagnostic difficulties

Propionibacterium species are members of the normal flora of skin and the mouth but their pathogenic potential is often overlooked. Three fatal cases of endocarditis caused by Propionibacterium species over an 8-year period are reported, and a review is presented of a further 33 cases from the world literature. In most cases, infection was protracted, with minimal signs in the early stages. Fourteen cases (42.4%) involved native valves, 16 (48.5%) involved prosthetic valves and three (9.1%) were associated with other intracardiac prosthetic material. Intracardiac abscesses were commonly encountered, with Propionibacterium endocarditis occurring in 28.6% of native valve infections and 52.9% of prosthetic valve infections. A very high proportion of all of the cases (70.6%) required surgical intervention. Several factors appeared to delay institution of appropriate therapy and may have contributed to abscess formation, including an indolent clinical course, negative or delayed culture results, and the tendency to consider this organism as a blood-culture contaminant. The authors recommend careful clinical evaluation before disregarding a blood-culture isolate of Propionibacterium spp. as a skin contaminant, and consideration of this bacterium as a potential cause of apparently culture-negative endocarditis.

Propionibacterium acnes

Propionibacterium acnes, a common skin organism, is most notably recognized for its role in acne vulgaris. It also causes postoperative and device-related infections and has been associated with a number of other conditions such as sarcoidosis and synovitis, acne, pustulosis, hyperostosis and osteitis (SAPHO), although its precise role as a causative agent remains to be determined. Propionibacterium acnes produces a number of virulence factors and is well known for its inflammatory and immunomodulatory properties. Recent publication of the P. acnes genome should provide further insights into the pathogenic capabilities of the organism and potentially lead to the development of new therapies.

Arthroplastic and osteosynthetic infections due to Propionibacterium acnes: a retrospective study of 52 cases, 1995–2002

The cases of 52 patients with Propionibacterium acnes infection of orthopaedic implants are summarized: 20 patients with definite infection (sepsis, with P. acnes recovered from multiple specimens per patient), 15 with probable infection (sepsis, with P. acnes recovered from one specimen), and 17 with possible infection (signs of prosthetic malfunction or pseudo-osteoarthritis, with P. acnes recovered from one specimen). The patient population consisted of 37 males and 15 females with a mean age of 51.8 years (range 17-88). Besides bone surgery, 21% of these patients had severe coexisting illness. The study population was very heterogeneous and clinical presentation very polymorphic; infections became clinically apparent through sepsis, prosthetic malfunction, or a delay in consolidation. The diagnosis was highly dependent on the quality of the samples taken and the methodology used by the microbiology laboratory to isolate this bacterium. Culture time was long, on average 11.4 days. Treatment involved a combination of antibiotic treatments (67% of cases) and ablation of the material (83% of cases). Although P. acnes is considered to be weakly pathogenic, this bacterium may be responsible for infections in patients with implanted orthopaedic material. Ablation of the arthroplastic or osteosynthetic material is necessary in the majority of cases.

Monitoring of apheresis platelet bacterial contamination with an automated liquid culture system: a university experience

BACKGROUND

With 4 million platelet units transfused per year in the United States and with the current estimate of bacteria contamination rate in PLT units, it would be expected that 2000 to 4000 bacterially contaminated units are transfused and associated with 333 to 1000 cases of clinical sepsis.

STUDY DESIGN AND METHODS

Apheresis platelets were sampled on Day 2 of storage (collection day=Day 0) and issue (or following outdate, Days 6-8) using a sterile connection device (SCD) to attach a sampling bag. Using aseptic technique and a laminar flow hood, bottles were inoculated and placed onto an automated liquid culture system (BacT/ALERT 3D Microbial Detection System) for 7 days.

RESULTS

A total of 2397 apheresis PLT units were sampled. A triple apheresis collection was reactive within 14 hours of the Day 2 sampling (aerobic bottles) and the bags were removed from inventory. Staphylococcus epidermidis was identified in all three contaminated bags. Two double-apheresis collections were found to be contaminated with Proprionibacterium sp. after 6 days of incubation but had been transfused to four patients without discernible clinical sequelae. There was one false-positive aerobic bottle and one false-positive anaerobic result due to inadvertent contamination of a bottle. Thus, the overall true-positive rate was 7 of 2397 apheresis units (0.29%) with a true-positive rate for aerobic organisms of 0.13% and an anaerobic true-positive rate of 0.17%. The false-positive rate was 2 out of 4794 samplings (0.04%) or 2 out of 9588 bottles (0.02%).

CONCLUSION

This preliminary data suggests that the use of a SCD, aseptic technique, and a laminar flow hood is associated with a low rate of contamination. In no case did an issue (or outdate) detect contamination that was not detected by the Day 2 culture. Additional surveillance is necessary before we can conclude that a Day 2 sterile culture is truly predictive of an issue (or outdate) sterile culture. Bacterial culture surveillance of PLTs would be expected to save lives and may facilitate an extension in PLT storage.

Propionibacterium acnes endocarditis in a native valve complicated by intraventricular abscess: a case report and review

Propionibacterium acnes is a constituent of the normal skin flora. It has been described as causing infection on prosthetic valves but very rarely on native valves. We describe a case of aggressive P. acnes endocarditis in a healthy 36-y-old man which infected a native aortic valve and was complicated by an aortic root abscess and review the literature.

Direct microscopic examination of imprints in patients undergoing cardiac valve replacement

BACKGROUND: Bacteriological analysis of cardiac valves might be indicated in patients with suspected endocarditis. METHODS: We report here a prospective study on fifty-three consecutive patients whose native valves were sent to the bacteriological and pathological laboratories, to investigate the performance of direct microscopic examination of imprints and valve culture. RESULTS: On the basis of a histopathological gold standard to classify the inflammatory valve process, the sensitivity, the specificity, the positive and the negative predictive values of direct microscopic examination of imprints and valve culture were 21%, 100%, 100%, 60%, and 21%, 72%, 38%, 52% respectively. This weak threshold of the direct microscopic examination of imprints could be due to antimicrobial therapy prescribed before cardiac surgery and the fact that the patients came from a tertiary hospital receiving patients with a prolonged history of endocarditis. CONCLUSION: Clinical context and histopathology are indispensable when analyzing the imprints and valve culture.

Ventricular patch endocarditis caused by Propionibacterium acnes: advantages of gallium scanning

Propionibacterium acnes is a weakly pathogenic commensal of the skin. When isolated from blood cultures it is often considered a contaminant. However, P. acnes may be responsible for severe infections and its role in certain cases of infectious endocarditis has now been definitely established.(1) We report a case of endocarditis due to P. acnes stemming from a ventricular patch and revealed by a gallium 67 scan.