DefinePK

Abstract

Background:    Cutibacterium  spp. is one of the most understudied bacteria and this is owed to its slow growing nature and its stringent requirement for anoxic conditions. To date, shortgun metagenomic sequencing and MALDI-TOF MS are widely used for species detection but, the latter is not able to distinguish  C. acnes  from  C. modestum  and  C. namnetense . Our study has innovatively combined colony morphology, biochemical assays and16s rRNA gene sequencing to identify  C. acnes  as well as the underreported  C. namnetense  and C.  modestum  from facial clinical acne samples. Methods:  The clinical samples were obtained using a non-invasive method from acne patients at the Dermatology Clinic of Hospital Tuanku Jaafar, Seremban, Malaysia between January 2022 to December 2022. Colonies of  Cutibacterium  spp. were screened on BHI agar followed by subjecting them to the catalase and indole tests. The isolates were verified as  Cutibacterium  spp. using API20A and 16s rRNA Sanger gene sequencing. Result:  Out of 68  Cutibacterium  spp. isolates, 3 were identified as  C. modestum  and 1 as  C. namnetense  while the rest were  C. acnes . All isolates were present as raised, white colonies with 0.03 to 1mm in diameter on BHI agar. 89.71% of these isolates were indole producers. All isolates were identified as  C. acnes  in API20A but, the 16srRNA gene sequencing revealed 4 isolates as  C. modestum  and  C. namnetense . Conclusion:  This study is the first to report the isolation of  C. namnetense  and  C. modestum  in clinical facial acne samples from Malaysia and across Asia, employing a modified combination of morphological, biochemical, and 16srRNA gene analyses. This methodical yet straightforward approach serves as a viable alternative in research settings lacking access to advanced techniques like MALDI-TOF and shotgun metagenomic sequencing. Moreover, this conventional isolation approach is valuable in assessing the sensitivity of the isolates to inhibitory agents apart from antibiotics, expanding researchers' abilities to develop potent antibacterial agents required for human health and wellbeing. Keywords:    Acne; Clinical Samples; Combinatorial; Identification