Are Cutibacterium acnes present at the end of primary shoulder prosthetic surgeries responsible for infection? Prospective study.

The purpose of this study was to investigate if the C. acnes present at the end of a primary shoulder arthroplasty could be responsible for shoulder arthroplasty infection. Prospective study includes patients undergoing primary shoulder arthroplasty from January 2015 until December 2018. From all the patients included, 5 to 12 tissue samples were obtained and were specifically cultured to detect the presence of C. acnes. DNA was extracted from the C acnes isolated colonies and Whole Genome Sequencing (WGS) analysis was done. A cohort of 156 patients was finally included. In twenty-seven patients, the C. acnes was present at the end of the primary surgery. Two of these patients developed a C. acnes periprosthetic shoulder infection at 6 and 4 months after the primary surgery. WGS of C. acnes isolated colonies showed that all the revision-surgery isolates clustered near to the corresponding primary-surgery isolates compared to the other independent bacterial colonies. (99.89% of similarity). C. acnes present at the end of the primary surgery can be the cause of early or delayed periprosthetic joint infections in shoulder arthroplasty.

Cutibacterium acnes clonal complexes display various growth rates in blood culture vials used for diagnosing orthopedic device-related infections.

OBJECTIVES: Blood culture bottles (BCBs) are commonly used for the diagnosis of infections associated with orthopedic devices. Although Cutibacterium acnes is an important pathogen in orthopedics, relatively little is known about its growth characteristics in BCBs. This prompted us to analyze the influence of bacterial genotype and clinical significance on time-to-detection (TTD) in BCBs. METHODS: We reviewed 59 cases of orthopedic device-related infections in which at least one intraoperative specimen yielded a pure C. acnes culture from anaerobic BCBs (BD Bactec Lytic/10 Anaerobic/F; Lytic-Ana) and/or solid media. A strain was considered infectant if the same genotype was present in two or more intraoperative samples. From these cases, we isolated a total of 72 unique C. acnes strains belonging to four multilocus sequence type clonal complexes (CCs): CC18, CC28, CC36 and CC53. Growth rate and TTD in Lytic-Ana BCB were studied under experimental conditions (inoculation of standard inoculum) and in clinical samples (inoculation of periprosthetic tissue samples). RESULTS: Median TTD values were shorter for CC53 compared to other CCs under experimental conditions (69 vs. 103 h; p < 0.001) and from clinical specimens (70 vs. 200 h; p = 0.02). Infectant strains had a shorter median TTD compared to contaminant strains in a clinical situation, while the difference was not observed under experimental conditions. CONCLUSIONS: The detection dynamics of C. acnes in Lytic-Ana BCBs were associated with genotype. Thus, TTD not only reflects the bacterial load in clinical samples, but may also reflect the intrinsic properties of the clonal complex of C. acnes.

Recognizing Cutibacterium acnes as a cause of infectious pericarditis: A case report and review of literature.

Cutibacterium acnes is an anaerobic bacterium commonly thought of as a culture contaminant rather than a pathogen. We present a case of Cutibacterium acnes pericarditis in a 22-year-old immunocompetent woman managed with surgical pericardial window and a 4-week course of penicillin G and review related literature on Cutibacterium acnes pericarditis.

Incidence of Cutibacterium acnes in open shoulder surgery.

In recent years, Cutibacterium acnes (C. acnes) has been reported to affect postoperative outcomes. The purpose of this study was to examine the detection rate and clinical features of C. acnes infection after open shoulder surgery. Fifty-nine patients (33 males and 26 females; mean age, 69.1 years) were included. Samples were collected from a skin swab at the incision site prior to skin preparation. Further samples were collected from synovial swabs at the glenohumeral joint immediately after incision and before incision closure. Samples with C. acnes-positive skin swab cultures were defined as Group A, and those with negative cultures were defined as Group N. Age, sex, presence of diabetes mellitus, operation time, presence of deep infection after surgery, and rate of positive synovial swab cultures were compared between groups. There were 27 patients in Group A (mean age 69.1±13.3 [SD], 21 males and 6 females) and 32 patients in Group N (mean age 69.1±11.0 [SD], 12 males and 20 females). No significant difference in the presence of diabetes mellitus and operation time were found between groups. From the glenohumeral joint immediately after incision, C. acnes was detected in 22.2% and 0% of patients in Group A and Group N, respectively. For the glenohumeral joint before incision closure, C. acnes was detected in 22.2% and 0% of patients in Group A and Group N, respectively, demonstrating a significantly higher rate in Group A. Our findings suggest that the route of infection following open shoulder surgery is via contamination.

A novel mutation in early-onset sarcoidosis/Blau syndrome: an association with Propionibacterium acnes.

BACKGROUND: Early-onset sarcoidosis (EOS) and Blau syndrome (BS) are systemic inflammatory granulomatous diseases without visible pulmonary involvement, and are distinguishable from their sporadic and familial forms. The diseases are characterized by a triad of skin rashes, symmetrical polyarthritis, and recurrent uveitis. The most common morbidity is ocular involvement, which is usually refractory to conventional treatment. A gain-of-function mutation in the nucleotide-binding oligomerization domain-containing protein 2 (NOD2) gene has been demonstrated in this disease; however, little is known about the relationship between the activation of NOD2 and the pathophysiology of EOS/BS. Here we describe EOS/BS with a novel mutation in the NOD2 gene, as well as detection of Propionibacterium acnes (P. acnes) in the granulomatous inflammation. CASE PRESENTATION: An 8-year-old Japanese girl presented with refractory bilateral granulomatous panuveitis. Although no joint involvement was evident, she exhibited skin lesions on her legs; a skin biopsy revealed granulomatous dermatitis, and P. acnes was detected within the sarcoid granulomas by immunohistochemistry with P. acnes-specific monoclonal (PAB) antibody. Genetic analyses revealed that the patient had a NOD2 heterozygous D512V mutation that was novel and not present in either of her parents. The mutant NOD2 showed a similar activation pattern to EOS/BS, thus confirming her diagnosis. After starting oral prednisolone treatment, she experienced an anterior vitreous opacity relapse despite gradual prednisolone tapering; oral methotrexate was subsequently administered, and the patient responded positively. CONCLUSIONS: We presented a case of EOS/BS with a novel D512V mutation in the NOD2 gene. In refractory granulomatous panuveitis cases without any joint involvement, EOS/BS should be considered as a differential diagnosis; genetic analyses would lead to a definite diagnosis. Moreover, this is the first report of P. acnes demonstrated in granulomas of EOS/BS. Since intracellular P. acnes activates nuclear factor-kappa B in a NOD2-dependent manner, we hypothesized that the mechanism of granuloma formation in EOS/BS may be the result of NOD2 activity in the presence of the ligand muramyl dipeptide, which is a component of P. acnes. These results indicate that recognition of P. acnes through mutant NOD2 is the etiology in this patient with EOS/BS.

A Retrospective Chart Review of Inflamed Epidermal Inclusion Cysts.

BACKGROUND: Epidermal inclusion cysts (EIC) are one of the most common forms of cysts found on and/or underneath the skin. Inflamed EICs typically show signs and symptoms such as pain and erythema, mimicking cutaneous abscess. However, prior studies have demonstrated at least 20% of lesions are culture negative. OBJECTIVE: To determine the rate of culture positivity in mild inflamed epidermal inclusion cysts, in particular to identify whether empiric antibiotics are warranted. METHODS: In a retrospective chart review 76 cases of inflamed EIC that were mild (lacking systemic symptoms) were analyzed who presented to the department of dermatology at Mount Sinai between 2016–2019. RESULTS: Of cultures taken from inflamed cysts, 47% resulted in no bacterial growth or growth of normal flora, 38.4% resulted in growth of aerobic bacteria with methicillin-resistant Staphylococcus aureus (8%), Staphylococcus lugdunensis (5%), and methicillin-sensitive Staphylococcus aureus (13%) predominating, and 9.3% resulting in growth of anaerobic bacteria with Finegoldia magna, Peptostreptococcus, and Cutibacterium acnes presenting. Review of prescribed treatment regimens often involved antibiotic medication, despite a high prevalence of negative culture. CONCLUSIONS: Almost half of cases of mild inflamed EIC (lacking systemic symptoms) cultured will not grow pathogenic bacteria, therefore incision and drainage with culture and appropriate therapy is a viable therapeutic option in uncomplicated inflamed EIC lesions. In this way, over prescription of antibiotics can be minimized. J Drugs Dermatol. 2021;20(2):199-202. doi:10.36849/JDD.5014.

Is there value in the routine practice of discarding the incision scalpel from the surgical field to prevent deep wound contamination with Cutibacterium acnes?

BACKGROUND: Cutibacterium acnes is found in skin flora of the shoulder and is the most common microbe identified in periprosthetic shoulder infections. The purpose of this study is to determine if there is C acnes present on the incision scalpel in patients undergoing shoulder arthroplasty despite extensive skin preparation techniques to prevent wound contamination. METHODS: The authors collected a consecutive case series of patients meeting inclusion criteria. Patients were included if they underwent either primary or revision shoulder arthroplasty at the tertiary care hospital with the senior author during the study period. Culture swab samples, testing for presence of C acnes, were collected from 17 consecutive patients who underwent shoulder arthroplasty with a single fellowship-trained surgeon between November 2019 and March 2020. Culture reports were recorded as "positive" or "negative" after 21 days. Institutional review board approval of the study protocol was obtained. The null hypothesis was that there would be no cases with knife blades "culture positive" for C acnes. RESULTS: 17 patients were identified and fit inclusion criteria. There were 12 men (mean age 64.3 years, range 48-79 years) and 5 women (mean age 69.8 years, range 59-79 years). Two patients (11.8%) were found to have C acnes growth on the skin knife. Both patients were male and older than 70 years undergoing primary reverse shoulder arthroplasty with no history of previous shoulder infections. CONCLUSION: The presence of C acnes on the skin blade in 2 patients validates concerns that there is C acnes present in dermal tissue despite extensive attention to eradication of these microbes. There was a high rate of C acnes contamination on scalpel blades used for initial skin incisions and the authors conclude that there is value in discarding these blades from the surgical field.

Oral Antibiotics for Acne.

Oral antibiotics are integral for treating inflammatory acne based on what is understood about the pathogenesis as well as the role of Cutibacterium acnes. However, rising concerns of antibiotic resistance and the perception of "antibiotic phobia" create potential limitations on their integration in an acne treatment regimen. When prescribing oral antibiotics, dermatologists need to consider dosage, duration, and frequency, and to avoid their use as monotherapy. These considerations are important, along with the use of newer strategies and compounds, to reduce adverse-event profiles, antibiotic resistance, and to optimize outcomes. Aside from concomitant medications, allergies, and disease severity, costs and patient demographics can influence variability in prescribing plans. There are multiple published guidelines and consensus statements for the USA and Europe to promote safe antibiotic use by dermatologists. However, there is a lack of head-to-head studies and evidence for comparative superiority of any individual antibiotic, as well as any evidence to support the use of agents other than tetracyclines. Although oral antibiotics are one of the main options for moderate to severe acne, non-antibiotic therapy such as isotretinoin and hormonal therapies should be considered. As newer therapies and more outcomes data emerge, so will improved management of antibiotic therapy to foster patient safety.

Acne vulgaris: new evidence in pathogenesis and future modalities of treatment.

Acne vulgaris, a common and chronic disorder of the pilosebaceous unit, affects up to 85% of adolescent and young adults. While a lot is already known about acne and its treatment, still the gaps in our understanding of acne remains. This article will review the emerging evidence in the complex pathogenesis of acne and provide an overview of the potential future therapy in management of acne vulgaris.Key pointsWhat is known? Propionibacterium acnes targeted therapy has been the mainstay in the management of acne till now.What is new? Sebocyte activity is controlled via a range of cellular pathways and hormones in addition to androgens. This has opened an array of therapeutic options to be available for treating acne in the near future.

Propionibacterium acnes-associated sarcoidosis complicated by acute bird-related hypersensitivity pneumonitis.

BACKGROUND: The number of reports on sarcoidosis complicated by hypersensitivity pneumonitis (HP) is limited, and most describe cases complicated by chronic bird-related HP. Here, we present for the first time a case with Propionibacterium acnes-associated sarcoidosis complicated by acute bird-related HP. CASE PRESENTATION: A 62-year-old man with a past medical history of sarcoidosis was admitted to our department, and chest computed tomography showed diffuse ground-glass opacities, which appeared as he rapidly increased the number of pigeons he kept for a competition. Random transbronchial lung biopsy revealed well-formed non-caseating epithelioid granulomas, which contained positively stained substances on immunohistochemistry using the PAB antibody, a specific monoclonal antibody against P. acnes lipoteichoic acid. Poorly formed non-caseating granulomas without positively stained substances were also detected. CONCLUSION: We describe the successful identification of this exceptionally rare case of sarcoidosis complicated by acute bird-related HP in which two morphologically and immunohistologically different types of granulomas were present in the same lung.

Antibiotic resistant Cutibacterium acnes among acne patients in Jordan: a cross sectional study.

BACKGROUND: Antibiotics have been used for decades against Cutibacterium acnes (previously known as Propionibacterium acnes; C. acnes). Alarmingly, antibiotic resistance to this bacterium has become a worldwide problem in recent years. No studies are available on the antibiotic susceptibility patterns of C. acnes among Jordanian acne patients and how that is influenced by antibiotic use. This study aims to assess antibiotic resistance patterns of C. acnes clinical isolates and neighboring Gram-positive normal flora of the skin obtained from acne patients attending dermatology clinics in Amman -Jordan appraising the role of antibiotic consumption. METHODS: This is a cross-sectional study of acne patients presenting to selected dermatology outpatient clinics over a 6-month study period. Swabs obtained from inflamed lesions were cultured aerobically and anaerobically. Isolates were identified and screened for antibiotic susceptibility. In addition, all patients were asked to fill in a questionnaire that included questions about the history of antibiotic treatment. RESULTS: C. acnes was isolated from lesions of 100 patients out of 115 participants included in this study. 73% of the isolates were resistant to erythromycin and 59% to clindamycin 37% to doxycycline, 36% to tetracycline, 31% to trimethoprim / sulfamethoxazole, 15% to levofloxacin, and 3% to minocycline. Multi drug resistance (MDR) in C. acnes isolates as well as Staphylococcus aureus (S. aureus) and Staphylococcus epidermidis (S. epidermidis) with a similar pattern of resistance were detected from the same patient in most cases. A pattern of higher resistance towards variable antibiotic was observed in patients previously treated with antibiotics for acne management. CONCLUSIONS: The findings of this study demonstrate the distribution of antibiotic resistance of C. acnes towards used antibiotics and emphasizes the influence of antibiotic consumption on development of antibiotic resistance. The similar pattern of resistance between skin bacteria tested in this study highlights the genetic transfer of resistance between skin commensals including S. aureus and S. epidermidis hence promoting its circulation in the community.

Anti-Acne Effects of Cembrene Diterpenoids from the Cultured Soft Coral Sinularia flexibilis.

Acne is a skin disease common in adolescents and increasingly common in the adult population. The major pathologic events of acne vulgaris include increased sebum production, retention hyperkeratosis, carrying commensal skin microbiota, and inflammation. In recent years, more than 10,000 compounds have been isolated and identified from marine organisms. The aim of this study was to discover the potential anti-acne activity of fraction 9 + 10 (SF-E) of Sinularia flexibilis extract and six cembrene diterpenoids. We found that the SF-E significantly reduced Cutibacterium acnes-induced edema in Wistar rat ears. The cembrene diterpenoids including 11-dehydrosinulariolide (SC-2), 3,4:8,11-bisepoxy-7-acetoxycembra-15(17)-en-1,12-olide (SC-7), and sinularin (SC-9) reduced nitric oxide (NO) production with 50% inhibitory concentration of 5.66 ± 0.19, 15.25 ± 0.25, and 3.85 ± 0.25 µM, respectively, and inducible NO synthase expression in RAW 264.7 cells. Moreover, treatment with SC-2, SC-7, and SC-9 significantly suppressed lipopolysaccharide- and heat-killed C. acnes-induced expression of proteins involved in mitogen-activated protein kinase pathway in both RAW 264.7 and HaCaT cells. After treatment with SC-2, SC-7, and SC-9, over-proliferation of HaCaT cells was significantly terminated. In summary, SC-2, SC-7, and SC-9 showed anti-inflammatory effects in RAW 264.7 cells, suggesting that these cembrene diterpenoids obtained from S. flexibilis are natural marine products with potential anti-acne activities.

Antibiotic Resistance in Acne: Mechanisms, Complications and Management.

Antibiotic resistance in acne was first observed in the 1970s, and since the 1980s has become a major concern in dermatologic daily practice. The mechanisms for this type of resistance include biofilm formation that promotes virulence and the transmission of resistant bacterial strains. Genetic mutations with modification of ribosomal RNA, alteration in efflux pumps, and enzymatic inactivation are able to create resistance to tetracyclines and macrolides. The state of art in acne treatment is no longer to use antimicrobials as monotherapy. There should be a time limit for its use plus the employment of non-antibiotic maintenance. Earlier initiation of oral isotretinoin therapy should be considered in patients with insufficient response to antimicrobials, severe acne, or a history of repeated antimicrobial use. A better understanding of acne pathogenesis, the subtypes of Propionibacterium (also known as Cutibacterium) acnes, homeostasis of the skin microbiota, and the mechanisms of antibiotic resistance would be useful in the selection of narrow-spectrum or species-specific antimicrobials, as well as the non-antimicrobial, anti-inflammatory treatment of acne. A number of novel treatments awaiting clinical proof may include the use of bacteriophages, natural or synthetic antimicrobial peptides, probiotics, and biofilm-targeting agents, as well as the reassessment of phototherapy.

Identifying and exploring biohydrogenating rumen bacteria with emphasis on pathways including trans-10 intermediates.

BACKGROUND: Bacteria involved in ruminal formation of trans-10 intermediates are unclear. Therefore, this study aimed at identifying rumen bacteria that produce trans-10 intermediates from 18-carbon unsaturated fatty acids. RESULTS: Pure cultures of 28 rumen bacterial species were incubated individually in the presence of 40 µg/mL 18:3n-3, 18:2n-6 or trans-11 18:1 under control or lactate-enriched (200 mM Na lactate) conditions for 24 h. Of the 28 strains, Cutibacterium acnes (formerly Propionibacterium acnes) was the only bacterium found to produce trans-10 intermediates from 18:3n-3 and 18:2n-6, irrespective of the growth condition. To further assess the potential importance of this species in the trans-11 to trans-10 shift, different biomass ratios of Butyrivibrio fibrisolvens (as a trans-11 producer) and C. acnes were incubated in different growth media (control, low pH and 22:6n-3 enriched media) containing 40 µg/mL 18:2n-6. Under control conditions, a trans-10 shift, defined in the current study as trans-10/trans-11 ≥ 0.9, occurred when the biomass of C. acnes represented between 90 and 98% of the inoculum. A low pH or addition of 22:6n-3 inhibited cis-9, trans-11 CLA and trans-10, cis-12 CLA formation by B. fibrisolvens and C. acnes, respectively, whereby C. acnes seemed to be more tolerant. This resulted in a decreased biomass of C. acnes required at inoculation to induce a trans-10 shift to 50% (low pH) and 90% (22:6n-3 addition). CONCLUSIONS: Among the bacterial species studied,C. acnes was the only bacterium that have the metabolic ability to produce trans-10 intermediates from 18:3n-3 and 18:2n-6. Nevertheless, this experiment revealed that it is unlikely that C. acnes is the only or predominant species involved in the trans-11 to trans-10 shift in vivo.

Low sensitivity of histopathological examination of peri-implant tissue samples in diagnosing postoperative spinal implant infection.

AIMS: To evaluate the histopathological examination of peri-implant tissue samples as a technique in the diagnosis of postoperative spinal implant infection (PSII). METHODS: This was a retrospective analysis. Patients who underwent revision spinal surgery at our institution were recruited for this study. PSII was diagnosed by clinical signs, histopathology, and microbiological examination of intraoperatively collected samples. Histopathology was defined as the gold standard. The sensitivity for histopathology was calculated. A total of 47 patients with PSII and at least one microbiological and histopathological sample were included in the study. RESULTS: PSII occurred in approximately 28% of the study population. Histopathology showed a sensitivity of 51.1% in the diagnosis of PSII. The most commonly found pathogens were Cutibacterium acnes and gram-positive staphylococci. CONCLUSION: Histopathology has low sensitivity for detecting PSII. In particular, infections caused by low-virulence microorganisms are insufficiently detected by histopathology. Cite this article: Bone Joint J 2020;102-B(7):899-903.

High rate of unexpected positive cultures in presumed aseptic revision of stiff shoulders after proximal humerus osteosynthesis.

BACKGROUND: The aim of this study was to investigate the prevalence of positive microbiology samples after osteosynthesis of proximal humerus fractures at the time of revision surgery and evaluate clinical characteristics of patients with positive culture results. METHODS: All patients, who underwent revision surgery after locked platting, medullary nailing or screw osteosynthesis of proximal humeral fractures between April 2013 and July 2018 were retrospectively evaluated. Patients with acute postoperative infections, those with apparent clinical signs of infection and those with ≤1 tissue or only sonication sample obtained at the time of implant removal were excluded. Positive culture results of revision surgery and its correlation with postoperative shoulder stiffness was analyzed in patients with an interval of ≥6 months between the index osteosynthesis and revision surgery. RESULTS: Intraoperatively obtained cultures were positive in 31 patients (50%). Cutibacterium acnes was the most commonly isolated microorganism, observed in 21 patients (67.7%), followed by coagulase negative staphylococci in 12 patients (38.7%). There were significantly more stiff patients in the culture positive group compared to the culture-negative group (19/21, 91% vs. 15/26, 58%, p = 0.02). Furthermore, 11 of 12 (91.7%) patients with growth of the same microorganism in at least two samples had a stiff shoulder compared to 23 of 35 (65.7%) patients with only one positive culture or negative culture results (p = 0.14). CONCLUSION: Infection must always be considered as a possibility in the setting of revision surgery after proximal humerus osteosynthesis, especially in patients with postoperative stiffness.

Case Report: A Polymicrobial Vision-Threatening Eye Infection Associated with Polysubstance Abuse.

We report a patient with risk factors for both microbial keratitis and endophthalmitis, which were initially challenging to distinguish. Cultures of corneal scrapings yielded several organisms, including an uncultivable Gram-negative rod, eventually identified as Kingella negevensis. Kingella negevensis is so named because most strains have been isolated in the Negev, a desert region of southern Israel. The epidemiology of K. negevensis remains incompletely understood. We found no other reports in the literature of this organism causing microbial keratitis.

Cutibacterium subtype distribution on the skin of primary and revision shoulder arthroplasty patients.

BACKGROUND: The skin of healthy shoulders is known to harbor multiple different subtypes of Cutibacterium (formerly Propionibacterium) acnes at the same time. C acnes can often be isolated from deep tissue and explant samples obtained during revision of a failed shoulder arthroplasty, presumably because the shoulder was inoculated with organisms from the patient's skin at the time of the index arthroplasty. It is possible that specific subtypes or distributions of subtypes may be associated with an increased pathogenic potential and that the skin of patients undergoing revision arthroplasty contains different distributions of the subtypes than in patients undergoing primary arthroplasty. We analyzed the subtype distribution of Cutibacterium from the skin of shoulders undergoing revision arthroplasty vs. primary arthroplasty. METHODS: Preoperative skin swabs were collected from 25 patients who underwent primary shoulder arthroplasty and 27 patients who underwent revision shoulder arthroplasty. The results of semiquantitative cultures of the skin and deep tissues were reported as specimen Cutibacterium values, and scores from all deep tissue samples were added to report the total shoulder Cutibacterium score. Single-locus sequence typing (SLST) of C acnes from the skin swabs was used to determine the subtype distribution for each patient. The percentage of each subtype for each patient was averaged in patients undergoing revision arthroplasty and then compared with that in patients undergoing primary arthroplasty. RESULTS: The C acnes subtype distribution on the skin of revision arthroplasty patients was different from that of primary shoulder arthroplasty patients, with a significantly higher percentage of SLST subtype A (36.9% vs. 16.0%, P = .0018). The distribution of SLST subtypes was similar between revision arthroplasty patients with strongly positive culture findings vs. those with weakly positive or negative culture findings. CONCLUSIONS: Significant differences in the skin Cutibacterium subtype distributions were found between shoulders undergoing revision shoulder arthroplasty and those undergoing primary shoulder arthroplasty. Future studies are needed to determine whether certain Cutibacterium subtype distributions are associated with an increased risk of arthroplasty revision.

Topical Minocycline Foam 4%: A Review in Acne Vulgaris.

Topical minocycline foam 4% (Amzeeq™) is approved in the USA for the treatment of inflammatory lesions of non-nodular, moderate to severe acne vulgaris (acne) in patients aged ≥ 9 years. It was developed to minimize systemic minocycline absorption and toxicity, and its high lipid content allows efficient drug movement through sebum and into affected sites. The favorable in vitro resistance profile of oral minocycline seen in Cutibacterium acnes (C. acnes) isolates was maintained with topical minocycline foam 4%. In 12-week, phase III clinical trials, once-daily topical minocycline foam 4% significantly improved both inflammatory and noninflammatory lesions relative to foam vehicle in patients aged ≥ 9 years with moderate to severe acne and was reported by most patients to be satisfactory or highly satisfactory to use. Extension trial data indicated that topical minocycline foam 4% continued to be effective for up to 52 weeks' therapy. Topical minocycline foam 4% was generally well tolerated in these patients, with most adverse events (AEs) and all serious AEs considered to be unrelated to treatment. Cutaneous AEs were uncommon, and findings from a dermal safety study showed that topical minocycline foam 4% did not have any effects related to phototoxicity, photoallergy, skin sensitization and skin irritation. Topical minocycline foam 4% is thus a useful addition to available treatment options for the management of inflammatory lesions of non-nodular, moderate to severe acne in adult and pediatric patients aged ≥ 9 years.