Propionibacterium acnes Susceptibility and Correlation with Hemolytic Phenotype

Abstract

BACKGROUNDMany studies have noted an increase in the number of recognized cases of invasive infections due to Propionibacterium acnes, especially after shoulder replacement surgery. The increase in the number of recognized cases of P. acnes, a nonspore-forming, anaerobic, Gram-positive organism, appears due to both an increase in the number of shoulder operations being performed and more specimens being sent for anaerobic cultures. Nevertheless, the optimal surgical and antibiotic management of P. acnes remains controversial.METHODSWe tested the susceptibility of 106 P. acnes strains from sterile body sites collected at the Erie County Medical Center between 2012 and 2015, using Etest gradient antibiotic strips.RESULTSP. acnes is very susceptible to the penicillins and the first-generation cephalosporins. We noted an association between hemolytic phenotype on Brucella Blood Agar and clindamycin resistance.CONCLUSIONSAntimicrobial susceptibility testing of P. acnes should no longer just be confined to the research laboratory but expanded and incorporated into routine microbiological evaluation of P. acnes. This would improve patient care as well as help clarify the relationship between hemolysis and clindamycin resistance.

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

“…Additionally, there was a correlation between doxycycline resistance and blue light resistance in that the strains most resistant to tetracyclines also seemed to be resistant to blue light alone. Although this finding is somewhat clouded by the difficulty in determining antibiotic resistance breakpoints for tetracyclines in C. acnes, this correlation is reminiscent of our previous finding of a link between hemolytic phenotype and clindamycin resistance [27]. This correlation is perplexing as resistance to tetracyclines is often achieved by up-regulation of efflux pumps or by mutations in ribosomal RNA, neither of which suggest an obvious pathway that would be sensitive to blue light.…”

“…C. acnes presents something of a paradox to clinicians and microbiologists. Despite being highly sensitive to most antibiotics used for peri-operative prophylaxis 12 , 27 , C. acnes is able to survive and cause PJI 20 , 35 . This ubiquitous anaerobic, non-motile and non-spore forming Gram-positive bacterium resides in the deep dermis, sebaceous glands, and hair follicles especially in the shoulder region and appears to persist even after commonly used pre-operative skin disinfectants, such as chlorhexidine 20 .…”

“…acnes strains isolated from Musculoskeletal Infection Society (MSIS) determined shoulder PJIs. Of these strains, 9 were from the collection of Crane et al 12 and 10 were from the collection reported by Wright et al 27 .…”

Pathogenic genetic variations of C. acnes are associated with clinically relevant orthopedic shoulder infections

“…Recent studies from our institution have shown beta‐hemolytic activity expressed phenotypically as hemolysis to correlate clinically with true orthopedic shoulder infections, possibly serving as a marker for virulence 2. Strains exhibiting hemolysis have also shown a high percentage (31%) of clindamycin resistance compared with non‐hemolytic strains (0%) 19,38 . In this study the Definite Infection group contained samples that expressed hemolytic activity with increased expression of CAMP2.…”

“… 18 Hemolytic strains were noted to have enhanced pathogenic features with prominent systemic inflammatory response, increased antibiotic resistance and challenging clinical course with higher treatment failure rates. Multiple previous studies have noted the hemolytic phenotype of C. acnes to be associated with pathogenicity 2,16,19,20 …”