Bacteria known to cause skin and soft tissue infections were uncovered in microbiological studies of the skin disease hidradenitis suppurativa (HS), with nearly 60% of cultures dominated by Staphylococcus lugdunensis, according to a study published online November 13 in Emerging Infectious Diseases.
Although the results do not prove that the bacteria are the causative agent, they do support antibiotic treatment of HS, say authors Hélène Guet-Revillet, MD, from the Université Paris Descartes, Sorbonne Paris Cité, Paris, France, and colleagues.
The research group studied the microbiology of 102 HS lesions from 82 patients using prolonged bacterial cultures and conducted bacterial metagenomics on six samples which uncovered two microbiological profiles among these lesions.
Also known as acne inversa and Verneuil disease, HS is found in 1% to 2% of the population. Previous microbiological studies found a range of bacteria associated with HS lesions, but these were usually considered contaminants of the primary lesions.
No satisfactory treatment of HS exists, but studies published in 2009 and 2010 showed the efficacy of rifampin-clindamycin combinations, and a study published in Dermatology in 2012 showed complete healing with rifampin-moxifloxacin-metronidazole combinations.
In this study, researchers cultured all patients referred to the Centre Médical de l'Institut Pasteur from June 2007 to February 2011. Patients who received systemic or topical antibiotic drugs a month or more before sampling were excluded from the study.
The analysis showed two main profiles for HS. Profile A made up 58% of the cultures and showed S lugdunensis as the unique or predominant isolate. Profile B contained a mixture of anaerobic flora made up of strict anaerobes and/or anaerobic actinomycetes and/or streptococci of the milleri group. Other bacterial species were occasionally present in small amounts in the mixed anaerobic profile B.
Five samples corresponded with neither profile. Two of those were pure cultures of Propionibacterium acnes; two were of corynebacteria, enterobacteriaceae, and coagulase-negative staphylococci; and one was a pure culture of Streptococcus pyogenes, probably associated with an unrelated acute infectious syndrome.
"Altogether, our study demonstrates that HS lesions are associated with bacterial species that can cause abscesses and severe infections," the authors report. Further investigations comparing cultures from open suppurating lesions found anaerobes, actinomycetes, and streptococci of the milleri group associated with purulent drainage, biopsies, and aspirations, but did not find them in cultures from perilesional swabs, leading the authors to conclude that they are associated specifically with HS.
Findings showing that Staphylococcus aureus, non-lugdunensis coagulase negative staphylococci, corynebacteria, enterobacteriaceae, and Propionibacterium species were isolated from swabs and drainage, but rarely from biopsies, suggest these groups are probably present as contaminants of the HS.
Profile A was associated "almost exclusively" with Hurley stage 1 lesions, whereas profile B was predominantly associated with Hurley stage 2 and 3 lesions, the authors found. Profile A tended to be associated with lesions of the breast and buttocks.
"In summary, this study demonstrates that bacterial pathogens known to cause soft tissue and skin infections are found in HS lesions," the authors write. "The unexpected efficacy of wide-spectrum antimicrobial treatments for HS highly suggests that these bacteria are partly causative agents for suppurative hidradenitis and should be considered to be treatment targets."
Emerg Infect Dis. Published online November 13, 2014. Full text
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