Antimicrobial activity of topical agents against Propionibacterium acnes： an in vitro study of clinical isolates from a hospital in Shanghai, China

This study aimed to compare the antimicrobial activities of topical agents against Propionibacterium acnes isolated from patients admitted to a hospital in Shanghai, China. The minimal inhibitory concentrations of the cultured P. acnes were determined in accordance with the Clinical and Laboratory Standards Institute. Susceptibilities to clindamycin and erythromycin were compared in terms of gender, age, disease duration, previous treatment, and disease severity. A total of 69 P. acnes strains were isolated from 98 patients （70.41%）. The susceptibility to triple antibiotic ointment （neomycin/bacitracin/polymyxin B） and bacitracin was 100%. The susceptibility to fusidic acid was 92.7%. The resistance rates to neomycin sulfate, erythromycin, and clindamycin were 11.7%, 49.3%, and 33.4%, respectively. The high resistance rate to clindamycin and erythromycin was significantly affected by gender, previous treatment, and disease severity rather than by age and disease duration. Topical antibiotics should not be used separately for long-term therapy to avoid multiresistance. The use of topical antibiotics should be determined by clinicians on the basis of clinical conditions.

Unexpected positive cultures including isolation of Propionibacterium acnes in revision shoulder arthroplasty

Objective Little information is available to guide treatment strategies regarding patients with unexpected positive cultures （UPC）,including Propionibacterium acnes （PA）,without overt signs of infection in revision shoulder arthroplasty （RSA）.The purpose of our study was to analyze the prevalence,clinical meaning,treatment and prognosis of UPC in RSA.Data sources and study selection We performed a systematic review of the literature between 1950 and 2013 for all studies reporting on UPC for PA.Studies with the prevalence and prognosis of patients with UPC in RSA were analyzed.Results Six studies meeting our inclusion criteria yielded data for 1 402 patients who underwent a total of 1405 RSA.Based on the available data,following RSA 235 shoulders had UPCs with a pooled percentage of 16.7％ （235/1405）.The most commonly isolated bacteria from shoulders following RSA with UPCs was PA with pooled percentages of 63.4％ （149/235）.Occurrence of true infection from UPCs after RSA was seen in 24 shoulders （24/235,10.2％）.Antibiotic use did not influence the rate of the occurrence of true infection from UPCs （P=0.498）.Conclusions Our study showed a low risk of having a true infection from UPCs after RSA without clinical signs of preoperative infection at the time of the surgery.Therefore,prolonged antibiotic therapy may not be necessary in these patients.

Mass Spectrometric Identification of Propionibacterium Isolates Requires Database Enrichment

Propionibacterium species are mostly environmental bacteria, some being commensal of mammals including humans, and sometimes pathogenic. These bacteria are poorly identified using routine laboratory methods. Recently, Matrix Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF-MS) has emerged as a rapid and efficient method to identify bacterial species. We evaluated the use of MALDI-TOF-MS for identification of all validated Propionibacterium species. Only four of the 15 tested reference strains (26.7%) were correctly identified at the species level, and P. acnes, the most common human pathogenic species was not identified. When applying MALDI-TOF-MS to 48 P. acnes strains, only 18.7% were correctly identified, suggesting an intraspecific variability of proteic profiles among Propionibacterium strains. However, by enriching the Bruker database with spectra from five of these strains and re-testing the other 43 strains against this new database, 93.0% were correctly identified. Our study demonstrates that MALDI-TOF-MS may be used for the identification of Propionibacterium isolates but requires a database enrichment in spectra from additional isolates.

Effects of cosmetics containing purified honeybee(Apis mellifera L.) venom on acne vulgaris

Acne vulgaris is a chronic dermatologic problem with multiple factors involved in its pathogenesis. Alternative solutions to acne treatment were instigated by antibiotic resistance despite of its extensive use. Purified bee venom （PBV） has been proposed as a promising candidate for that purpose. The present study was designed to confirm the antibacterial effect of PBV and access the efficacy of cosmetics containing PBV in subjects with acne vulgaris. METHODS： The skin bacterium Propionibacterium acnes was incubated with PBV at various concentrations and bacterial growth was evaluated using the colony forming unit （CFU） assay. The mechanism of PBV employed in killing P. acnes was examined by scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. In addition, a total of 12 subjects were randomized in a double-blind, controlled trial to receive either cosmetics containing PBV or cosmetics without PBV for two weeks. Evaluations included lesion counts and skin microorganism. RESULTS： PBV exhibited antimicrobial activity in a concentration-dependent manner, reducing the number of P. acnes CFU by approximately 6 logs at a concentration of 0.5 mg. When PBV concentration was higher than 1.0 mg, no P. acnes colonies were spotted on an agar. TEM and SEM of untreated P. acnes illustrated the normal pleomorphic structure, whereas the PBV- treated bacterium lost the integrity of surface architecture. Significant difference （P=0.027） in the grading levels based on numbers of lesion counts for inflammatory and noninflammatory was observed in favour of the PBV group compared with the control group. In terms of average decrement of skin microorganism, subjects receiving cosmetics containing PBV experienced a significant 57.5% decrease of adenosine triphosphate levels, whereas participants receiving cosmetics without PBV experienced a nonsignificant decrease of 4.7%. CONCLUSION： These results show that the in vitro actions of antimicrobial activity of PBV were translated in vivo. Cosmetics containing PBV provided a certain degree of efficacy in terms of lesion counts and skin microorganism concentration compared with cosmetics without PBV in subjects with acne vulgaris. PBV may be a good candidate compound for developing therapeutic drua for the treatment of acne vulaaris.

Pathogen characteristics and its sensitivity against antimicrobial agents in fatal bacterial granuloma after eyelid trauma in vitro

AIM: To understand the pathogen characteristics and its sensitivity against antimicrobial agents in fatal bacterial granuloma after eyelid trauma (FBGT) in vitro, and to provide laboratory evidence for diagnosis. METHODS: The FBGT pathogens were isolaated and cultured with reformed rabbit-brain anaerobic enriched broth (RRAB), and identified by ATB/API 20A system. The minimum inhibiting concentration (MIC) was determined by anaerobic broth dilution method. RESULTS: A total of 22 strains of pathogen were separated from 21 patients with FBGT and identified as Propionibacterium acnes (PA) by ATB/API 20A system. The MIC of ciprofloxacin for 22 PA strains was 0.0625-0.5mg/L, the MIC of penicillin, ampicillin, ampicillin/sulbactam, cefoperazone, lincomycin, and imipenem/cilastatin were 0.125-0.5mg/L, the MIC of ticarcillin/clavulanic acid was 0.250-1.000mg/L, and the MIC of metronidazole was 64-256mg/L. The pathogen of FBGT was strictly anaerobic PA, which growed slowly and better in nutritious RRAB broth. All PA were resistant to metronidazole, but susceptive to other routine antimicrobial agents, such as penicillin, ampicillin and lincomycin. CONCLUSION: FBGT should not be treated with metronidazole. Clinicians should choose combined use of drugs or operation to treat FBGT according to patients' individual condition and the results of drug sensitivity test.