The Study Of Micrococcus Colonization On The Facial Lesions Of Patients With Melasma

Objective:(1)To discuss the difference of micrococcus on the skin surface of patients with melasma and healthy people.(2)To discuss the drug susceptibility of micrococcus.(3)To discuss the relationship between micrococcus colonization on the skin surface of melasma and skin barrier.Methods: Dermoscopy examination,Lab measurement,transepidermal water loss(TEWL)detection,stratum corneum hydration(SCH)detection,tape stripping were respectively performed on melasma lesions in 90 patients and the corresponding areas of90 healthy control subjects.The samples were cultured and isolated,and the single strain DNA was extracted.PCR amplification with the universal primers of bacteria were performed to identify the species by first-generation sequencing.The isolated micrococcus were tested with 12 antibiotic agents to understand the drug sensitivity.Results:(1)Among all the specimens of 90 patients with melasma,39 patients isolated with micrococcus luteus(M.luteus)(positive rate 43.33%),while all the specimens of 90 healthy control subjects,20 specimens isolated with M.luteus(positive rate 22.22%),the difference was statistically significant(P<0.05).(2)The test result of drug susceptibility of52 M.luteus in vitro isolated from facial skin lesion of 90 melasma cases to 12 antibiotics shows that the susceptibility to 9 antibiotics is more than 70.00%,with 100.00% to rifampicin,azithromycin,erythromycin,penicillinand doxycycline,96.15% to amikacin,94.23% to minocycline,90.38% to levofloxacin and 80.77% to polymyxin B,while that is low to clindamycin(48.08%),metronidazole(63.46%)and tetracycline(65.38%).The test result of susceptibility of 23 M.luteus in vitro isolated from facial corresponding areas of90 normal women to 12 antibiotics shows that the susceptibility to10 antibiotics is more than 70.0%,with 100.00% to minocyline,amikacin,rifampicin,azithromycin,erythromycin,penicillin and doxycycline,95.65% to levofloxacin,78.26% to tetracycline,73.91% to polymyxin B,while that is low to clindamycin(52.17%),metronidazole(69.57%).(3)In Melasma group,Lab A and Lab B value of M.luteus-positive group were higher than the negative group P<0.05).In Melasma group,the TEWL value of M.luteuspositive group was higher than the negative group(P<0.05).The SCH value of M.luteus positive group was lower than the negative group(P<0.05).Conclusion:(1)In patients with melasma,the colonization of M.luteus on the face are higher than normal women.The formation of melasma may be related to the yellow pigment produced exceeding the skin's self-cleansing ability which is produced by adhering and binding of M.luteus with epidermis due to its excessive colonization on skin surface.(2)M.luteus isolated from the skin lesions of melasma were sensitive to rifampicin,azithromycin,erythromycin,penicillin and doxycycline,which can provide theoretical basis for the antibiotics local treatment of melasma.(3)M.luteus may damage the skin barrier leading to increasement of TEWL,decreasement of SCH value.