Propionibacterium acnes Susceptibility and Correlation with Hemolytic Phenotype

Postoperative Endophthalmitis Caused by Cutibacterium (Formerly Propionibacterium) Acnes: Case Series and Review

We report the clinical features, treatment strategies and outcomes in a series of patients with infectious endophthalmitis after cataract surgery caused by Cutibacterium acnes (C. acnes), formerly known as Propionibacterium acnes (P. acnes). This retrospective case series includes six eyes of six patients with chronic postoperative endophthalmitis caused by culture-proven C. acnesfrom December 2010 to July 2019 at a University referral center. All patients underwent prior cataract extraction with intraocular lens (CE/IOL) implantation. The mean time between cataract surgery and the microbiologic diagnosis of endophthalmitis was 7.4 ± 5.2 months (range 1.5–17 months). The average time from obtaining the specimen to culture positivity was 7.7 ± 4.4 days (range 3–15 days). Three eyes (50%) presented with hypopyon and three eyes (50%) presented with prominent keratic precipitates without hypopyon. Presenting visual acuity ranged from 20/25 to 2/200. Initial treatments included intravitreal antibiotics alone (n = 2), pars plana vitrectomy (PPV) with partial capsulectomy and intravitreal antibiotics (n = 3), and pars plana vitrectomy with IOL removal and intravitreal antibiotics (n = 1). Follow-up treatments included IOL removal (n = 2), intravitreal antibiotics (n = 1), and topical antibiotics (n = 1). The best-corrected visual acuity at last follow-up was 20/70 or better in all patients. In a literature review, the clinical features and treatment outcomes for all case series of delayed-onset postoperative endophthalmitis caused by C. acnes(n = 120) are listed. A definitive cure (the absence of recurrent inflammation) was achieved in 100% of patients that underwent IOL removal, in 77% of those that underwent PPV/partial capsulectomy and intravitreal antibiotics, and in 18% of cases treated with intravitreal antibiotics alone. Endophthalmitis after CE/IOL caused by C. acnesis characterized by slowly progressive intraocular inflammation and has a protracted course from surgery to microbiologic diagnosis. Visual outcomes are generally favorable, but IOL explantation may be necessary for definitive cure.

Effect of Blue Light and Photosensitizers on Cutibacterium acnes on Shoulder Periprosthetic Joint Infection Isolates

Introduction:Cutibacterium acnes is gaining recognition as a leading pathogen after orthopaedic shoulder procedures. Photodynamic therapy, a combination of light and a photosensitizer, has demonstrated antimicrobial activity against C. acnes in the treatment of acne vulgaris. We sought to evaluate the effect of photodynamic therapy using blue light and photosensitizers on C. acnes isolates from shoulder prosthetic joint infections.

Methods:C. acnes strains isolated from 19 patients with shoulder PJI were exposed to blue light alone (415 nm) or in combination with photosensitizers (fluorescein, riboflavin and demeclocycline). C. acnes strains were divided into 4 categories: Highly Sensitive (HS), Sensitive (S), Weakly Sensitive (WS), Resistant to blue light.

Results: 13 of 19 C. acnes strains (68%) were S or HS to blue light alone. Of these 19 strains tested, 11 were tested with blue light and fluorescein or blue light plus riboflavin. Fluorescein (1 µg/mL) enhanced the effect of blue light in 6 of 11 strains (55%). Blue light plus riboflavin (10 µg/mL) resulted enhanced killing in 3 of 11 strains (27%), but produced a paradoxical photoprotective effect in 4 of 11 strains (36%), resulting in a net decrease compared to blue light alone. Demeclocycline, however, enhanced the effect of blue light in 16 of 17 strains (94 %).

Conclusions: Blue light with the addition of photosensitizers killed C. acnes from periprosthetic shoulder infections in vitro, with demeclocycline having the most pronounced effect.

Preparation of Clindamycin Hydrochloride Loaded De-Esterified Low-Methoxyl Mango Peel Pectin Film Used as a Topical Drug Delivery System

In this study, we aimed to develop a low-mexthoxyl pectin (LMP) from mango peel pectin through a de-esterification method for use as a film forming agent. The prepared de-esterified pectin (DP) was compared to commercial LMP (cLMP) which possessed a 29% degree of esterification (DE). Mango peel pectin was extracted from ripe Nam Dokmai mango peel using the microwave-assisted extraction method. Pectin derived from the mango peel was classified as a high mexthoxyl pectin (79% DE) with 75% of galacturonic acid (GalA) content. A de-esterification experiment was designed by central composite design to plot the surface response curve. Our prepared DP was classified as LMP (DE 29.40%) with 69% GalA. In addition, the Fourier-transform infrared spectrophotometer (FTIR) spectra of the DP were similar to cLMP and the pectin backbone was not changed by the de-esterification process. Strikingly, the cLMP and DP films showed non-significant differences between their physical properties (p > 0.05) with respect to the puncture strength (13.72 N/mm² and 11.13 N/mm² for the cLMP and DP films, respectively), percent elongation (2.75% and 2.52% for the cLMP and DP films, respectively), and Young’s modulus (67.69 N/mm² and 61.79 N/mm² for the cLMP and DP films, respectively). The de-esterified pectin containing clindamycin HCl (DPC) and low-methoxyl pectin containing clindamycin HCl (cLMPC) films demonstrated 93.47% and 98.79% of drug loading content. The mechanical properties of the cLMPC and DPC films were improved possibly due to their crystal structures and a plasticizing effect of clindamycin HCl loaded into the films. The DPC film exhibited a drug release profile similar to that of the cLMPC film. Our anti-bacterial test of the films found that the cLMPC film showed 41.11 and 76.30 mm inhibitory clear zones against Staphylococcusaureus and Cutibacteriumacnes, respectively. The DPC film showed 40.78 and 74.04 mm clear zones against S.aureus and C.acnes, respectively. The antibacterial activities of the cLMPC and DPC films were not significantly different from a commercial clindamycin solution. The results of this study suggest that mango peel pectin can be de-esterified and utilized as an LMP and the de-esterified pectin has the potential for use as a film forming agent, similar to cLMP. In addition, the remarkable use of de-esterified mango peel pectin to prepare films, as shown by our study, holds a great promise as an alternative material for anti-bacterial purposes.

Cutibacterium acnes persists despite topical clindamycin and benzoyl peroxide

BACKGROUND

Cutibacterium (formerly Propionibacterium) acnes persists in the dermis despite standard skin antiseptic agents, prompting some surgeons to use topical antimicrobials such as benzoyl peroxide and clindamycin prior to shoulder arthroplasty surgery. However, the efficacy of these topical agents has not been established.

METHODS

The upper backs of 12 volunteers were randomized into 4 treatment quadrants: topical benzoyl peroxide, topical clindamycin, combination topical benzoyl peroxide and clindamycin, and a negative control. The corresponding topical agents were applied to each site twice daily for 3 days. A 3-mm dermal punch biopsy specimen was obtained from each site and cultured for 14 days to assess for C acnes growth. Positive cultures were assessed for the hemolytic phenotype. The McNemar test was used to compare the proportion of positive cultures in each group.

RESULTS

C acnes grew in 4 of 12 control sites (33.3%), 1 of 12 benzoyl peroxide sites (8.3%), 2 of 12 clindamycin sites (16.7%), and 2 of 12 combination benzoyl peroxide-clindamycin sites (16.7%). The C acnes hemolytic phenotype was present in 2 of 12 control specimens (16.7%) compared with 0 (0.0%) in the benzoyl peroxide group, 2 of 12 (16.7%) in the clindamycin group, and 2 of 12 (16.7%) in the combination benzoyl peroxide-clindamycin group. There were no statistically significant differences between treatment arms.

CONCLUSION

The topical application of benzoyl peroxide and clindamycin did not eradicate C acnes in all subjects. The clinical implications of these findings are yet to be determined.

Nationwide Organism Susceptibility Patterns to Common Preoperative Prophylactic Antibiotics: What Are We Covering?

BACKGROUND

Many periprosthetic joint infections (PJIs) are caused by organisms not susceptible to first-generation cephalosporins. We sought to evaluate the national susceptibility patterns of organisms to cefazolin and, or oxacillin, clindamycin, and vancomycin using antibiogram data.

METHODS

Publically available regional and state antibiograms were evaluated for antibiotic susceptibility patterns to commonly infecting gram-positive organisms. The number of isolates tested in each antibiogram and percent of strains susceptible to oxacillin, clindamycin, and vancomycin were recorded. Oxacillin is used as a surrogate to cefazolin in antibiograms. A comparison of antibiotic susceptibilities was performed.

RESULTS

Seven state and 38 regional antibiograms were reviewed. Oxacillin was a sensitive antibiotic in 99.2 ± 4.8% of methicillin-sensitive Staphylococcus aureus (MSSA) isolates, 0 ± 0% of methicillin-resistant Staphylococcus aureus (MRSA) isolates, 44.5 ± 13.7% of coagulase-negative staphylococcus organism isolates (CNS), and 30.6 ± 10.5% of Staphylococcus epidermidis isolates. Clindamycin was a sensitive antibiotic in 75.8 ± 8.4% of MSSA isolates, 60.2 ± 13.2% of MRSA isolates, 60.3 ± 11.4% of CNS isolates, and 56.2 ± 6.5% of S epidermidis isolates. Vancomycin was a sensitive antibiotic in 99.9 ± 0.4% of MSSA isolates, 99.8 ± 0.4% of MRSA isolates, 99.8 ± 0.5% of CNS isolates, and 99.6 ± 0.7% of S epidermidis isolates. Clindamycin was significantly less sensitive in MSSA isolates as compared with oxacillin and vancomycin (P < .0001). Oxacillin was significantly less sensitive in CNS, S epidermidis, and MRSA isolates as compared with clindamycin and vancomycin (P < .0001).

CONCLUSION

The national clindamycin susceptibility pattern is limited to MSSA and may not have an optimal susceptibility profile suitable for use as a prophylactic antibiotic. Cefazolin continues to have excellent coverage against MSSA.

Cutibacterium acnes (formerly Propionibacterium acnes) isolated from prosthetic joint infections is less susceptible to oxacillin than to benzylpenicillin

Introduction: The frequency of prosthetic joint infections (PJIs) due to Cutibacterium acnes (formerly Propionibacterium acnes) is increasing, especially shoulder PJIs. The recommended antibiotic prophylaxis for hip and knee arthroplasties is beta-lactam antibiotics, predominantly cephalosporins. However, for example in Sweden, isoxazolyl-penicillin cloxacillin is used. No specific recommendations for shoulder arthroplasties are available. The aim of the present study was to determine the minimum inhibitory concentration (MIC) values for different antibiotics for C. acnes; and, more specifically, to compare the MIC values for benzylpenicillin and oxacillin. Materials and methods: Minimum inhibitory concentration (MIC) values for nine different antibiotic agents were obtained by gradient test (Etest) using strains of C. acnes (n= 57) isolated from PJIs from shoulders (n=31), hips (n=21), and knees (n=5). Results: All isolates had low MIC values for most of the tested antibiotic agents, and showed a wild type MIC distribution. The exception was clindamycin with 9% of the isolates displaying decreased susceptibility. The MIC values obtained for benzylpenicillin were significantly lower than the MIC values for isoxazolyl-penicillin (oxacillin). Conclusion: These in vitro results indicate that benzylpenicillin might be a more effective prophylactic treatment to prevent shoulder PJIs caused by C. acnes. However, further studies on the subject are needed, and the effectiveness of the prophylactic treatment should be evaluated using randomized controlled studies and/or register-based studies.

Importance of Propionibacterium acnes hemolytic activity in human intervertebral discs: A microbiological study

Most patients with chronic lower back pain (CLBP) exhibit degenerative disc disease. Disc specimens obtained during initial therapeutic discectomies are often infected/colonized with Propionibacterium acnes, a Gram-positive commensal of the human skin. Although pain associated with infection is typically ascribed to the body's inflammatory response, the Gram-positive bacterium Staphylococcus aureus was recently observed to directly activate nociceptors by secreting pore-forming α-hemolysins that disrupt neuronal cell membranes. The hemolytic activity of P. acnes in cultured disc specimens obtained during routine therapeutic discectomies was assessed through incubation on sheep-blood agar. The β-hemolysis pattern displayed by P. acnes on sheep-blood agar was variable and phylogroup-dependent. Their molecular phylogroups were correlated with their hemolytic patterns. Our findings raise the possibility that pore-forming proteins contribute to the pathogenesis and/or symptomology of chronic P. acnes disc infections and CLBP, at least in a subset of cases.

The Use of Antibiograms in Orthopedic Surgery

PURPOSE OF REVIEW

Organism identification and antibiotic selection remain a critical component of periprosthetic joint infection (PJI) treatment. Prior to organism identification and/or the availability of antibiotic sensitivities, empiric antibiotics are routinely started. A basic understanding of a region or institutions antibiogram is paramount for selection of an empiric treatment regimen. Evolving antibiogram results and regional antibiotic resistance are important to follow as this may change antibiotic selection in some patient populations.

RECENT FINDINGS

The Clinical Laboratory and Standards Institute (CLSI) has created guidelines and standards for the creation and maintenance of antibiograms that should be followed by institutions. The infecting organism during PJI may be different in acute vs chronic infections and empiric therapy may change depending on the timing. Antibiotic prophylaxis for major procedures in certain patient populations should be critically evaluated based on regional and national antibiogram results. The CLSI guides recommendations and antibiotic resistance testing techniques and should be consulted when creating an antibiogram. The local and regional antibiogram should be consulted prior to administration of empiric and prophylactic antibiotics.

Low-Virulence Organisms and Periprosthetic Joint Infection-Biofilm Considerations of These Organisms

PURPOSE OF REVIEW

The purpose of this manuscript is to provide a critical review of peer-reviewed literature over the last 5 years related to low virulent organisms associated with periprosthetic joint infection (PJI). We evaluated the most common organisms, the diagnostic challenges, and the novel tools available in the perioperative workup of PJI as well as the current understanding of how biofilm potentiates the indolent clinical presentation and explore a possible shift in the surgical management of these patients.

RECENT FINDINGS

Biofilm actively prevents macrophage phagocytosis by suppressing proinflammatory activity through the recruitment of myeloid-derived suppressor cells. Given the appropriate host and organism conditions, increased utilization of one-stage exchange arthroplasty in the surgical treatment of these low virulent infections may be on the rise. Biomarkers and molecular techniques offer encouraging results to diagnose low virulent organisms and future research focused on the disruption of biofilm may ultimately give rise to improved treatment strategies.

Antibiotic Prophylaxis and Prevention of Surgical Site Infection in Shoulder and Elbow Surgery

Infection after orthopedic procedures is a devastating and serious complication associated with significant clinical and financial challenges to the health care system and unfortunate patient. The time and resource-intensive nature of treating infection after orthopedic procedures has turned attention toward enhancing prevention and establishing quality improvement measures. Prevention strategies throughout the perioperative period include host optimization, risk mitigation, reducing bacterial burden and proper wound management. Understanding the most common offending organisms of the shoulder, Propionibacterium acnes and coagulase negative Staphylococcus species, and their hypothesized mechanism of infection is crucial to selecting appropriate preventative measures.